Tag Archives: Virginia

Hurricane Jose Turns Back Toward U.S.

Hurricane Jose completed the long slow clockwise loop it made this week over the Atlantic Ocean and it turned back toward the U.S.  At 5:00 p.m. EDT on Friday the center of Hurricane Jose was located at latitude 27.1°N and longitude 70.3°W which put it about 640 miles (1025 km) southeast of Cape Hatteras, North Carolina.  Jose was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 983 mb.

An eye appeared to be forming at the center of Hurricane Jose as the primary rainband wrapped around the eastern and northern portions of the developing eye.  The strongest winds were occurring in that rainband.  Additional bands of showers and thunderstorms were revolving around the eastern half of the circulation.  There were fewer showers and thunderstorms in the western half of the circulation.

Hurricane Jose is moving over the part of the Atlantic Ocean that the hurricane traversed several days ago.  So, Jose is moving over cooler water that it mixed to the surface when it moved over the area the first time.  Hurricane Jose will soon move northwest of its previous track and it will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds will be weak and there will be little vertical wind shear.  Hurricane Jose will strengthen during the weekend and it could intensify rapidly once the eye and eyewall are fully formed.

After a few days of weak steering currents the large subtropical high pressure system over the Atlantic Ocean has started to steer Hurricane Jose toward the northwest.  A general northwesterly motion is forecast to continue for another 24 to 36 hours.  At that time Jose will reach the western end of the high and it will turn more toward the north.  On its anticipated track Hurricane Jose could be near the Outer Banks of North Carolina in two or three days.  It is still too early to know if the center of Hurricane Jose will move into the U.S.

Tropical Storm Irma Still Bringing Gusty Winds and Storm Surges to Southeast U.S.

Tropical Storm Irma was still bringing gusty winds, locally heavy rain and storm surges to parts of the Southeastern U.S. on Monday afternoon.  Gusty winds were blowing down trees and bringing down power lines in parts of Florida, Georgia, South Carolina and North Carolina.  Locally heavy rainfall resulted in the issuance of Flood Watches and Warnings for portions of those states.  Strong winds were blowing water toward the coast in northeastern Florida, Georgia and South Carolina.  Storm surges caused flooding in Jacksonville, Florida and Savannah, Georgia.  The water level at Charleston, South Carolina was higher than it was during Hurricane Matthew in 2016.

At 5:00 p.m. EDT on Monday the center of Tropical Storm Irma was located at latitude 31.5°N and longitude 84.0°W which put it about 10 miles (15 km) east of Albany, Georgia.  Irma was moving toward the north-northwest at 17 m.p.h.  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 985 mb.

A Tropical Storm Warning remained in effect for the portion of the coast from Altamaha Sound to South Santee River.

The structure of Tropical Storm Irma evolved as it moved further inland.  Drier air wrapped around the  western side of the circulation.  Convergence between a large surface high north of Irma and the tropical storm produced heavy rain northeast of the center of circulation.  The heaviest rain fell over Georgia, South Carolina and the western half of North Carolina.  The northern edge of the rain shield was moving over Tennessee and southeast Kentucky.  The pressure difference between the high and Irma also generated strong winds in the eastern half of Irma’s circulation.  Those strong winds pushed water toward the coast in northern Florida, Georgia and South Carolina.  The wind caused storm surges of up to 10 feet (3 meters) in some locations.  Water was reported in parts of downtown Jacksonville, Florida and Charleston, South Carolina.

Tropical Storm Irma will continue to move toward the north-northwest and weaken.  The circulation of Irma is very large, and it will take a few more days to spin completely.  There could be stronger winds in the high elevations of Appalachian Mountains.  Locally heavy rain could also create the potential for floods in some valleys.  The storm surges along the coast should gradually subside as the wind speeds decrease.

Elsewhere, Hurricane Jose was moving northward east of the Bahamas.  At 5:00 p.m. EDT on Monday the center of Hurricane Jose was located at latitude 31.5°N and longitude 84.0°W which put it about 555 miles (895 km) east of Nassau, Bahamas.  Jose was moving toward the north at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 973 mb.  Hurricane Jose is forecast to make a slow clockwise loop this week.  On it anticipated track Hurricane Jose could still be east of the Bahamas at the end of the week.

Hurricane Matthew Causing Serious Flooding in the Carolinas

Hurricane Matthew produced heavy rainfall which led to serious flooding in South Carolina and North Carolina on Saturday.  The total rainfall in some locations exceeded 10 inches (25 cm) in numerous locations in those two states.  Heavy prolonged rain caused creeks and rivers to rapidly rise and flood.

The National Hurricane Center (NHC) still classified Hurricane Matthew as a hurricane in its 11:00 p.m. EDT advisory.  At 11:00 p.m. EDT on the center of Hurricane Matthew was located at latitude 34.1°N and longitude 76.5°W which put it about 35 miles (55 km) south of Cape Lookout, North Carolina.  Matthew was moving toward the east-northeast at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 982 mb.

A Hurricane Warning is in effect for the portion of the coast from Little River Inlet to Surf City, North Carolina.  A Hurricane Watch has been issued for the portion of the coast from Surf City to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Tropical Storm Warning is in effect for the portion of the coast from Surf City to Duck, North Carolina including Pamlico and Albemarle Sounds.

According to NHC the center of Hurricane Matthew made an official landfall near Cape Romain southeast of McClellanville, South Carolina at 11:00 a.m. EDT on Saturday.  Since that time the center of Hurricane Matthew has moved back out over the Atlantic Ocean.  New bands of showers are forming closer to the center south of the coast of North Carolina.  The winds to hurricane force are occurring over a small area on the southwestern side of Hurricane Matthew.

Easterly winds blowing around the north side of Hurricane Matthew converged with northerly winds blowing along a cold front to generate a broad area of rising motion.  The rising motion and the existing rainbands of the hurricane combined to produce very heavy rain over South Carolina and the southeastern half of North Carolina.  The area of heavy rain spread into southeastern Virginia around Norfolk on Saturday night.  The prolonged heavy rainfall caused the water in creeks and rivers to rise very quickly.  Serious flooding was occurring in parts of South Carolina and North Carolina.  Numerous roads were closed because of flooding in those two states.

Along the coast of North Carolina southeasterly winds were blowing water toward the coast and Hurricane Matthew was still generating storm surges.  When Matthew moves east of the Outer Banks of North Carolina, the wind will change direction and it will blow from the northwest.  Those northwesterly winds will push water in Pamlico and Albemarle Sounds onto the western sides of the Outer Banks.  Storms surges caused by Hurricane Matthew caused varying amounts of damage from Florida to North Carolina.  The most destructive storm surges appear to have been near Jacksonville Beach, Florida, around the barrier islands of Georgia and South Carolina.  However, a full damage assessment has not been made of those locations at this time.

Even though the center of Hurricane Matthew stayed over the Atlantic Ocean most of the time, gusty winds caused power outages from Florida to North Carolina.  As the heavy rain saturated the ground, gusts of winds toppled trees which fell onto power lines.  More power outages are likely in eastern North Carolina and southeastern Virginia as more trees are uprooted.

Hurricane Matthew will slowly move out to sea on Sunday.  Matthew appears to be making a transition to an extratropical cyclone.  During that transition the wind field is likely to expand.  So, conditions should improve slowly over North Carolina and Virginia on Sunday.

Hurricane Matthew Brings Wind, Rain and Surge to Northeast Florida

Hurricane Matthew brought gusty winds, heavy rain and storm surges to northeast Florida as the center of the hurricane moved northward just east of Florida on Friday.  A weather station on the tip of Cape Canaveral reported a wind gust to 107 m.p.h. (170 km/h) when the western side of the eyewall moved over that location.  Wind gusts to 71 m.p.h. (115 km/h) were reported at Daytona Beach.  A wind gust to 86 m.p.h. (139 km/h) was reported by a C-MAN station in St. Augustine, Florida.  Some wind damage and numerous power outages were reported in conjunction with the strong winds.  Easterly winds pushing water toward the coast were generating storms surges along the coast.

At 5:00 p.m. EDT on Friday the center of Hurricane Matthew was located at latitude 30.2°N and longitude 80.7°W which put it about 40 miles (65 km) east of Jacksonville Beach, Florida and about 135 miles (215 km) south of Savannah, Georgia.  Matthew was moving toward the north at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 948 mb.  Hurricane Matthew was a Category 2 hurricane on the Saffir-Simpson Scale.

A Hurricane Warning is in effect for the portion of the coast from the Flagler/Volusia County line in Florida to Surf City, North Carolina.  A Tropical Storm Warning is in effect for the portion of the coast from Surf City to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Tropical Storm Warning is also in effect for the portion of the coast from the Brevard/Volusia County lie to the Volusia/Flagler County line in Florida.

The eye and the core of Hurricane Matthew remained over the Atlantic Ocean as Matthew moved parallel to the east coast of Florida.  Occasionally, the western side of the eyewall would move over the coast and bring stronger winds to those areas.  The remnants of the smaller inner eyewall dissipated during the afternoon.  Once the eyewall cycle was completed the remaining outer eyewall began to contract.  Thunderstorms around the eye generated enough upper level divergence to pump out mass and limited the increase of the surface pressure.  As a result, a strong pressure gradient force is still producing winds of over 100 m.p.h. (160 km/h) in the north and northeastern parts of the eyewall.

Hurricane Matthew has been moving around the western end of a subtropical high pressure system which steered the hurricane toward the north on Friday.  An upper level trough over the Central U.S. will move east and southwesterly winds with the trough will start to steer Matthew toward the northeast later tonight.  It is not clear exactly when the turn will occur and the exact timing of the turn to the northeast is very important.  If Hurricane Matthew continues to move north, the northern eyewall which contains the strongest winds could reach Savannah and the coast of South Carolina in 6-10 hours.  If those winds reach the coast, then the damage will be more severe.  If Hurricane Matthew turns northeast before the northern eyewall reaches the coast, then the damage will be less.

Even though Hurricane Matthew weakened slightly to a Category 2 hurricane and is no longer officially a major hurricane, it is still capable of causing regional serious damage.  Matthew will cause wind damage and widespread power outages along the coasts of Georgia and South Carolina, even if the center of the eye does not officially make landfall.  If the center of the eye brings the northern eyewall over the coast, the winds will be much stronger and the damage will be greater.  In addition, easterly winds on the northern side of Hurricane Matthew will drive water toward the coast and create serious storm surges.  In places where the shape of the coast funnels water into smaller areas, the surges will be even more dangerous.

Hurricane Matthew Develops Concentric Eyewalls on Its Way Toward Florida

The structure of Hurricane Matthew changed on Thursday as it strengthened on its way toward Florida.  A second larger outer eyewall formed around the small tight inner eye and eyewall.   At 5:00 p.m. EDT on Thursday the center of Hurricane Matthew was located at latitude 26.2°N and longitude 78.6°W which put it about 25 miles (40 km) south-southeast of Freeport, Bahamas and about 100 miles (160 km) east-southeast of West Palm Beach, Florida.  Matthew was moving toward the northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (270 km/h).  The minimum surface pressure was 938 mb.  Hurricane Matthew was a Category 4 hurricane on the Saffir-Simpson Scale.

A Hurricane Warning is in effect for the portion of the coast from Golden Beach, Florida to South Santee River, South Carolina including Lake Okeechobee.  A Tropical Storm Warning is in effect for the portion of the coast South Santee River, South Carolina to Surf City, North Carolina.  A Tropical Storm Warning is in effect for the portion of the coast from Anclote River, Florida to Suwanee River.  A Tropical Storm Warning is in effect for the portion of the coast from Chokoloskee to Golden Beach, Florida and for the Florida Keys from Seven Mile Bridge eastward including Florida Bay.  A Tropical Storm Watch has been issued for the portion of the coast from Chokoloskee, Florida to Anclote River.  A Hurricane Warning is in effect for the northwestern Bahamas including the Abacos, Andros Island, Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.

Hurricane Matthew began to strengthen early on Thursday morning.  The minimum surface pressure decreased from 961 mb at 11:00 p.m. EDT on Wednesday night to 940 mb at 8:00 a.m. EDT on Thursday morning.  A decrease of 17 mb in nine hours is a very rapid pressure fall, but the maximum wind speed only increased from 115 m.p.h. ((185 km/h) to 125 m.p.h. (205 mk/h) during that time period.  The rapid decrease in pressure and the increase in the pressure gradient force around the center of Hurricane Matthew contributed to the reformation of a small circular eye at the center of the hurricane.  Once the new eyewall was established, the wind speed increased to 140 m.p.h. (225 km/h) within three hours.

The structure of the circulation of Hurricane Matthew continued to improve during the day on Thursday as the hurricane moved over the very warm water around the Bahamas.  A circular inner eye with a diameter of 18 miles (29 km) was surrounded by a ring of strong thunderstorms.  A rainband wrapped all the way around the original eye and eyewall and a second outer eyewall formed.  The outer eyewall has a diameter of 70 miles (105 km).  The strongest winds in Hurricane Matthew are occurring in the inner eyewall.  Hurricane Matthew has maintained a double eyewall structure in recent hours.

Matthew is moving through an environment that is favorable for hurricanes.  The Sea Surface Temperature is near 30°C.  There upper level winds are weak and there is not much vertical wind shear.  Hurricane Matthew is likely to maintain its current intensity as long as the inner eyewall remains intact.  If the inner eye starts to dissipate, then the strongest winds would be found in the outer eyewall, but those winds are not as strong as the winds in the inner eyewall.  So the intensity of Hurricane Matthew would decrease if that happened.  However, the wind field of a hurricane typically gets larger if the outer eyewall becomes the strongest part of the circulation.

Hurricane Matthew is moving around the western end of a subtropical high pressure system which is steering it toward the northwest and that general motion is expected to continue until the hurricane gets close to the coast of Florida.  When Hurricane Matthew gets close to the coast, it will be at the western end of the high and the hurricane will turn north.  It is still unclear if the turn will occur just before Matthew reaches the coast or whether it will occur after the center of Matthew moves on shore.  Eventually, when Hurricane Matthew moves farther north, an upper level trough approaching form the west will steer it toward the northeast, but the timing of that turn is still uncertain too.

The future track of Hurricane Matthew will be a critical factor in determining the damage it causes.  If Matthew turns north before it reaches the east coast of Florida, the the strongest winds would stay over the Atlantic Ocean.  The same holds true for the turn toward the northeast.  If the turn occurs before Hurricane Matthew reaches Georgia and South Carolina, then the strongest winds would stay offshore.  A much more destructive scenario would unfold if Hurricane Matthew reaches the coast of Florida and then turns north.  If Matthew grinds its way north along the coast, the strongest winds and highest storm surge would occur.  Matthew could move over cities like Daytona Beach and Jacksonville.  If the turn to the northeast is delayed, then Matthew would also move near Savannah, Georgia and Charleston, South Carolina.

The Hurricane Intensity Index (HII) for Hurricane Matthew is 28.2.  The Hurricane Size Index (HSI) is 18.4 and the Hurricane Wind Intensity Size Index (HWISI) is 46.6  The indices indicate that Hurricane Matthew is stronger than Hurricanes Frances and Jeanne were when they hit southeast coast of Florida in 2004.  Matthew is smaller than Frances and Jeanne were in 2004.  The HWISI for Matthew is similar to the ones for Frances and Jeanne, which would suggest that Matthew is capable of causing similar damage.  Hurricane Frances cause 11 billion dollars of damage in 2004.  Hurricane Jeanne caused about 8 billion dollars of damage.  So, Hurricane Matthew has the potential to be a very destructive hurricane, but the damage it does will be determined by its ultimate path.  Matthew will do much less damage if the core of the hurricane stays offshore.

Hurricane Matthew will bring gusty winds and heavy rain to the southeast coast of Florida on Thursday night.  It will do the same to the northeast coast of Florida on Friday.  Strong easterly winds on the northern side of the center of circulation will drive water toward the shore and create dangerous storm surges as Hurricane Matthew moves along the coast.  The heavy rain is likely to cause fresh water flooding in some locations.  Hurricane Matthew could have the greats impact on the coasts of Georgia and South Carolina on Friday night and Saturday.

Post Tropical Storm Hermine Creates Coastal Flood Risk for Northeast U.S.

Although the structure of Tropical Storm Hermine changed significantly on Saturday and the National Hurricane Center designated it as Post Tropical, it still is creating a risk for coastal flooding for the northeastern U.S.  The size of the circulation of Hermine and its proximity to the U.S. is allowing its winds to push water toward portions of the coast.  The largest immediate risk is for the coasts of Virginia, Delaware and New Jersey.  When Hermine moves north, the greater risk will shift to New York, Rhode Island and Massachusetts.

At 11:00 p.m. EDT on Saturday the center of Post Tropical Storm Hermine was located at latitude 36.5°N and longitude 72.1°W which put it about 205 miles (330 km) southeast of Ocean City, Maryland.  Hermine was moving toward the east-northeast at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 998 mb.

A Tropical Storm Warning is in effect for the portion of the coast from Ocracoke Inlet, North Carolina to Watch Hill, Rhode Island including the Chesapeake Bay from Drum Point southward, Delaware Bay, New York City and Long Island.  A Tropical Storm Watch is in effect from Watch Hill, Rhode Island to Sagamore Beach, Massachusetts including Block Island, Martha’s Vineyard and Nantucket.

The circulation of Hermine changed from a tropical cyclone with a tight inner core to structure where area with the maximum wind speed is farther from the center.  In addition all of the thunderstorms near the center dissipated and most of the remaining thunderstorms are well northeast of the center of circulation.  The loss of tropical characteristics are the reason why the National Hurricane Center designated Hermine as Post Tropical.

Future changes of Hermine could continue to be complex.  Dry air has permeated the inner 100 miles (160 km) of the circulation which is devoid of any thunderstorms.  An upper level trough over the northeastern U.S. is forecast to move over the top of Hermine and cut off.  The would create a vertical structure which is the opposite of what is normally found in a tropical cyclone.  However, Hermine is moving over water where the Sea Surface Temperature (SST) is near 30°C.  A combination of cold air aloft in the upper low and warm SSTs could create enough instability to generate the development of new thunderstorms closer to the core of the circulation.  it is possible that Hermine could make a transition back to a more tropical cyclone like structure during the next several days.

The upper level trough is currently steering Hermine toward the east-northeast.  When the trough approaches Hermine, it will steer the storm more toward then north.  However, when the trough moves over the top of Hermine, the steering currents will be weak and Hermine could stall south of Long Island.  It is possible that the counterclockwise rotation in the upper trough could cause the storm to loop once or twice.  If Hermine makes a slow counterclockwise loop, it could move back closer to the coast of New Jersey on Monday.

The wind field in Hermine expanded during the structural changes.  Winds to tropical storm force extend out about 200 miles (320 km).  That makes Hermine about half as big as Hurricane Sandy was in 2012.

Hurricane Hermine Making Landfall in North Florida

After intensifying into a hurricane on Thursday, Hurricane Hermine is making landfall near St. Marks, Florida.  At midnight EDT the center of Hurricane Hermine was located at latitude 29.8°N and longitude 84.2°W which put it about 20 miles (30 km) south of St. Marks, Florida.  Hermine was moving toward the north-northeast at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 984 mb.

A Hurricane Warning is in effect from Suwannee River to Mexico Beach, Florida.  A Hurricane Watch is in effect from Anclote River to Suwannee River and from Mexico Beach to the Walton County/Bay County line.  A Tropical Storm Warning is in effect from Englewood to Suwannee River and from Mexico Beach to the Walton County/Bay County line.  A Tropical Storm Warning is also in effect from the Flagler County/Volusia County line to Duck, North Carolina including Pamlico and Albemarle Sounds.  A Tropical Storm Watch is in effect from Duck, North Carolina to Sandy Hook, New Jersey including the Chesapeake Bay from Smith Point southward and southern Delaware Bay.

The circulation of Hurricane Hermine organized quickly on Thursday.  It developed an eye with a mostly complete eyewall.  Spiral rainbands developed with strong winds in the eastern half of the circulation.  Upper level divergence to the east of Hermine pumped out mass and allowed the surface pressure to decrease.  The circulation is still asymmetrical with most of the stronger winds east of the center, but it looks a lot more typical of hurricanes that move toward the northern coast of the Gulf of Mexico.

Hurricane Hermine will weaken after it makes landfall.  It could interact with a cold front moving into the southeastern U.S.  It is possible that Hermine could develop a hybrid structure that is part tropical and part extratropical.  Hermine could have winds to tropical storm force as it passes over the Mid-Atlantic coast.  The stronger winds are likely to be out over the Atlantic Ocean and winds should be weaker farther inland.

An upper level trough is steering Hurricane Hermine toward the north-northeast and a general northeasterly motion is expected to continue for another 36 hours.  Later in the weekend a surface high pressure system could move north of Hermine and stall its progress.  Hermine could be stationary for a time.  On its anticipated track center of Hermine is likely to pass east of Tallahassee, Florida.  The center could pass north of Savannah, Georgia before coming near Charleston, South Carolina.  Hermine is likely to move near Cape Hatteras, North Carolina and out into the Atlantic Ocean.

Hurricane Hermine is capable of causing regional minor wind damage.  It is likely to cause widespread power outages.  The coast of the northeastern Gulf of Mexico is susceptible to storm surges and high water will effect that area overnight.  Locally heavy rainfall will create the potential for flooding.  When rainbands move ashore, wind shear could spin up tornadoes.  As Hermine moves near the Mid-Atlantic coast, easterly winds could cause water rises.

The Hurricane Intensity Index (HII) for Hurricane Hermine is 11.5.  The Hurricane Size Index (HSI) is 14.0.  The Hurricane Wind Intensity SIze Index (HWISI) is 25.5.  These indices are very similar to the ones for Hurricane Isaac before it hit the coast of Louisiana n 2012.  The HII for Isaac was 11.5.  Its HSI was 16.7 and its HWISI was 28.2.  This means that Hurricane Hermine is as strong and just smaller than Hurricane Isaac was just before it made landfall.  Hurricane Isaac did hit a more populated and more built up region.  Hurricane Isaac did 970 million dollars worth of insured damage.  It caused 407 million dollars to be paid out for flood insurance.  It is estimated that Hurricane Isaac caused 2.35 billion dollars worth of damage in the U.S.

Tropical Storm Hermine Strengthens, Hurricane Warning Issued

Tropical Storm Hermine strengthened on Wednesday evening and a Hurricane Warning was issued for a portion of the northern Florida coast.  A Hurricane Warning was in effect for the portion of the coast from Suwannee River to Mexico Beach, Florida.  A Hurricane Watch and a Tropical Storm Warning was in effect for the portions of the coast from Anclote River to Suwannee River and from Mexico Beach to Destin, Florida.  The Tropical Storm Watch was extended farther up the Mid-Atlantic coast.  The Tropical Storm Watch was in effect for the portion of the coast from Marineland, Florida to South Santee River, South Carolina.

At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Hermine was located at latitude 25.8°N and longitude 87.0°W which put it about 295 miles (475 km) south-southwest of Apalachicola, Florida.  Hermine was moving toward the north-northeast at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 998 mb.

The circulation of Tropical Storm Hermine became better organized on Wednesday, but it is still not really well organized.  A tighter center of circulation developed.  However, the wind field is still asymmetrical.  The stronger winds are mainly east of the center and the winds are weaker in the western half of the circulation.  An area of strong thunderstorms developed near the center and another cluster of thunderstorms persisted southwest of the center.  There are not many thunderstorms northwest of the center.  There are some spiral rainbands, but they are fragmented.

Tropical Storm Hermine is in an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  The upper level flow pattern is enhancing the divergence of mass to the northeast of Hermine.  The enhanced upper level divergence pumped out enough mass to allow the surface pressure to decrease by a few millibars on Wednesday evening.  Tropical Storm Hermine is expected to continue to intensify on Thursday and it should become a hurricane before it makes landfall on Thursday night.

The upper level ridge that was blocking a northward motion of Hermine has weakened.  So, the tropical storm has begun to more toward the north-northeast.  An upper level trough is expected to steer Hermine a little faster toward the northeast on Thursday.  On its anticipated track Hermine could make landfall somewhere between Apalachicola and Tarpon Springs, Florida on Thursday night.  After it moves across northeast Florida, Hermine could move near the coast of Carolinas on Friday.

Hermine is likely to be a hurricane when it makes landfall on Thursday night.  The core of the circulation which will contain the highest winds is likely to be fairly small and Hermine is likely to cause localized minor wind damage.  There will undoubtedly be power outages.  The coastline around the northeastern Gulf of Mexico is vulnerable to storm surges and Hermine will also produce a storm surge which could range up to 7 to 8 feet (2 to 2.5 meters) near where the center crosses the coast.  The storm surge will be less farther away from where the center makes landfall.  In addition Hermine will generate locally heavy rain which could cause fresh water flooding.  Directional wind shear associated with rainbands moving inland could spin up tornadoes in the eastern half of Hermine.

Tropical Depression Eight Prompts Tropical Storm Warning for North Carolina

The approach of Tropical Depression Eight and the potential for intensification prompted the National Hurricane Center to issue a Tropical Storm Warning for the portion of the coast from Cape Lookout to Oregon Inlet, North Carolina including Pamlico Sound.

At 5:00 p.m. EDT on Monday the center of Tropical Depression Eight was located at latitude 33.6°N and longitude 74.0°W which put it about 140 miles (225 km) southeast of Cape Hatteras, North Carolina.  It was moving toward the northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1011 mb.

Vertical wind shear disrupted the circulation of Tropical Depression Eight earlier today, but more thunderstorms developed northwest of the center of circulation during the afternoon.  The circulation is still not well organized, but there are indications on radar that it could be developing a tighter center.  An upper level low centered near Savannah, Georgia is producing southerly winds which are causing the moderate vertical wind shear over the depression.  The upper level winds are blocking upper level divergence to the south of Tropical Depression Eight, but there are some sign that upper level divergence could be occurring to the northeast.

Tropical Depression Eight could move into an area marginally more favorable for intensification.  As it gets farther from the upper level low, the winds aloft will decrease.  The depression is moving near the Gulf Stream and the Sea Surface Temperatures are near 29.5°C.  If thunderstorms persist near the center of circulation and a more coherent vertical structure develops, the the depression could strengthen into a tropical storm.

The upper low is steering Tropical Depression toward the northwest and that general motion is expected to continue for another day or so.  When the depression reaches latitude 35°N, westerly winds will begin to steer it off toward the northeast.  On its anticipated track Tropical Depression Eight could be very near Cape Hatteras in 24 to 36 hours.

Although Tropical Depression Eight will bring some stronger winds, locally heavy rain, rip currents, higher waves and beach erosion are greater risks.

Tropical Depressions Form South of Key West & Southeast of Cape Hatteras

Two tropical depressions formed near the U.S. on Sunday.  Tropical Depression Nine formed south of Key West, Florida and Tropical Depression Eight formed southeast of Cape Hatteras, North Carolina.  Both depressions could have an impact on the U.S., but Tropical Depression Nine could pose a greater risk to the southeastern U.S.

At 5:00 p.m. EDT on Sunday the center of Tropical Depression Nine was located at latitude 23.7°N and longitude 81.7°W which put it about 60 miles (95 km) south of Key West, Florida.  It was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1009 mb.

At 5:00 p.m. EDT on Sunday the center of Tropical Depression Eight was located at latitude 31.8°N and longitude 70.9°W which put it about 355 miles (570 km) southeast of Cape Hatteras, North Carolina.  It was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1010 mb.

The circulation of Tropical Depression Nine is still organizing.  A NOAA plane found a distinct center of circulation, but most of the stronger thunderstorms are south and east of the center.  There is a broader counterclockwise rotation with numerous showers and thunderstorms indicated by the National Weather Service radar in Key West.  An upper level low east of Florida is contributing to easterly winds that are blowing across the northern side of the depression.  The vertical wind shear is inhibiting the development of thunderstorms north and west of the center.

The circulation of Tropical Depression Eight was more well organized earlier today.  Strong easterly winds from the same upper level low that is affecting Tropical Depression Nine are creating significant vertical wind shear.  Those winds and the shear they caused blew the upper portion of the depression’s circulation west of the low level center of circulation.  The low level circulation is presently exposed as seen on visible satellite imagery and by an Air Force Reserve Hurricane Hunter aircraft.

The intensity forecast for Tropical Depression Nine is challenging because it is moving through a complex environment.  The depression is moving over water where the Sea Surface Temperature is near 31°C.  So, there is plenty of energy in the upper ocean.  However, as mentioned above, an upper low is causing vertical wind shear which will inhibit intensification.  Tropical Depression Nine could move into a region where there is less shear when it moves over the Gulf of Mexico.  Tropical Depression Nine has a good chance to intensify into a tropical storm, but it is unclear if it could become a hurricane before it reaches the coast.

There is also significant uncertainty in the track forecast for Tropical Depression Nine.  A ridge over the southeastern U.S. is steering the depression toward the west and that general motion should continue for several more days.  The ridge is forecast to weaken during the middle of the week and that should allow Tropical Depression Nine to turn toward the north.  The timing of that turn and how sharp it will be are still uncertain.

The upper low is expected to continue to generate wind shear over Tropical Depression Eight.  If the upper levels winds remain as strong as they are now, the depression will slowly weaken.  If the upper level winds weaken, then Tropical Depression Eight could strengthen into a minimal tropical storm.  The upper level low is steering the depression west and that general motion is expected to continue in the short term.  The depression could stall just off the coast of North Carolina.

Tropical Depression Nine could intensify and bring wind and rain to the Gulf Coast later this week.  The Gulf Coast is also vulnerable to storm surges.  Given the uncertainty in both the track and intensity, interests along the coast should monitor official sources of information for updates on Tropical Depression Nine.  The primary effects of Tropical Depression Eight are likely to be higher than normal surf, rip currents and some beach erosion along the North Carolina coast.  People along the Mid-Atlantic coast should pay attention to the depression in case the forecast changes.