Monthly Archives: July 2020

Hurricane Isaias Forces Hurricane Warning for Florida

The threat posed by Hurricane Isaias forced the issuance of a Hurricane Warning for Florida on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Hurricane Isaias was located at latitude 22.6°N and longitude 75.7°W which put it about 195 miles (320 km) south-southeast of Nassau, Bahamas.  Isaias was moving toward the northwest at 15 m.p.h. (24 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 991 mb.

A Hurricane Warning was in effect for the portion of the coast from Boca Raton, Florida to the Volusia/ Brevard County Line.  Hurricane Warnings were also in effect for all of the Bahamas including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, the Ragged Islands, Cat Island, the Exumas, Long Island, Rum Cay, San Salvador, Andros Island, New Providence, Eleuthera, the Abacos, the Berry Islands, Grand Bahama Island and Bimini.  Hurricane Watches were in effect for the portions of the coast from the Flagler/Volusia County Line to the Volusia/Brevard County Line and from Hallendale Beach to Boca Raton.  Tropical Storm Warnings were in effect for the Turks and Caicos, Ocean Reef to Boca Raton, Florida and Lake Okeechobee.  A Tropical Storm Watch was in effect for the portion of the coast from Flagler. Volusia County Line to Ponte Vedra, Florida.

The core of Hurricane Isaias exhibited greater organization on Friday afternoon.  Images from weather radar in the Bahamas and microwave sensors onboard satellites indicated that an eyewall was wrapping around the center of circulations.  The strongest winds were occurring in the ring of storms in the developing eyewall.  Storms near the center of Isaias were generating upper level divergence which was pumping mass away from the hurricane.  Bands of showers and thunderstorms were revolving around the core of Hurricane Isaias.  Winds to hurricane force extended out 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extended out 175 miles (280 km) from the center.

Hurricane Isaias will move through an environment favorable for intensification during the next 24 hours.  Isaias will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Isaias will strengthen on Saturday and it could intensify more rapidly once the inner core is fully formed.  Isaias could intensify into a major hurricane while it moves over the Bahamas.

Hurricane Isaias will move around the western end of a subtropical high pressure system over the North Atlantic Ocean.  The high will steer Isaias toward the northwest during the next 24 hours.  It will turn the hurricane more toward the north during the weekend when Isaias reaches the western end of the high pressure system.  On its anticipated track Hurricane Isaias will move over the Central Bahamas on Friday night.  Isaias could approach southeast Florida on Saturday.  Hurricane Isaias could approach the coast of the Carolinas on Monday.  Hurricane Isaias will bring strong winds to the southeast coast of Florida.  Those winds will blow the water toward the coast and they will create a dangerous storm surge.  Isaias will continue to produce strong winds and locally heavy rain in the Turks and Caicos and the Bahamas. Heavy rain could cause flash floods. Hurricane Isaias will also generate a dangerous storm surge in parts of the Bahamas.

Isaias Rapidly Intensifies into a Hurricane Southeast of the Bahamas

Former Tropical Storm Isaias rapidly intensified into a hurricane southeast of the Bahamas on Thursday night.  At 11:40 p.m. EDT on Thursday the center of Hurricane Isaias was located at latitude 20.3°N and longitude 72.1°W which put it about 70 miles (110 km) east-southeast of Great Inagua.  Isaias was moving toward the northwest at 18 m.p.h. (30 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 995 mb.

Hurricane Warnings were issued for all of the Bahamas including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, the Ragged Islands, Cat Island, the Exumas, Long Island, Rum Cay, San Salvador, Andros Island, New Providence, Eleuthera, the Abacos, the Berry Islands, Grand Bahama Island and Bimini. Tropical Storm Warnings were in effect for the entire coast of the Dominican Republic, Le Mole St. Nicholas, Haiti to the northern border with the Dominican Republic, the Turks and Caicos.  A Tropical Storm Watch was in effect for the portion of the coast from Ocean Reef to Sebastian Inlet, Florida.

A reconnaissance plane sampling former Tropical Storm Isaias on Thursday night found winds to hurricane force and a decrease in surface pressure.  The core of Hurricane Isaias organized quickly after it moved over the warm water north of the Dominican Republic.  A band of strong thunderstorms wrapped around the western side of the center of circulation.  Winds to hurricane force extended out about 30 miles to the northeast of the center of circulation.  Winds to tropical storm force extended out 240 miles (390 km) to the north and east of Isaias in the parts of the circulation that were over water.  Thunderstorms near the center of circulations were generating upper level divergence which pumped mass away from the tropical storm and allowed the pressure to decrease.   Brands of thunderstorms were wrapping around the eastern and northern sides of the circulation.

Hurricane Isaias will move through an environment favorable for intensification during the next 36 hours.  Isaias will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Hurricane Isaias will strengthen on Friday and it could intensify more rapidly once an inner core consolidates.  Isaias could intensify into a major hurricane while it moves over the Bahamas.

Hurricane Isaias will move around the western end of a subtropical high pressure system over the North Atlantic Ocean.  The high will steer Isaias toward the northwest during the next 36 hours.  It will turn the hurricane more toward the north on the weekend when Isaias reaches the western end of the high pressure system. On its anticipated track Hurricane Isaias will move over the Southeastern Bahamas on Friday morning.  Isaias will move over the Central Bahamas later on Friday and it could approach southeast Florida on Saturday.  Hurricane Isaias could approach the coast of the Carolinas on Monday.  Hurricane Isaias will bring strong winds and locally heavy rain to the Turks and Caicos and the Bahamas.  Heavy rain could cause flash floods.  Hurricane Isaias will also generate a dangerous storm surge in the Bahamas.

Tropical Storm Isaias Reorganizes North of Dominican Republic, Watch Issued for South Florida

The circulation around Tropical Storm Isaias reorganized near the northern coast of the Dominican Republic on Thursday afternoon and Tropical Storm Watches were issued for part of the coast of southeast Florida.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Isaias was located at latitude 19.5°N and longitude 70.6°W which put it about 25 miles (40 km) southeast of Puerto Plata, Dominican Republic.  Isaias was moving toward the northwest at 20 m.p.h. (32 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 999 mb.

Tropical Storm Warnings were in effect for the entire coast of the Dominican Republic, Le Mole St. Nicholas, Haiti to the northern border with the Dominican Republic, the Turks and Caicos, the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, the Ragged Islands, Cat Island, the Exumas, Long Island, Rum Cay, San Salvador, Andros Island, New Providence, Eleuthera, the Abacos, the Berry Islands, Grand Bahama Island and Bimini.  A Tropical Storm Watch was in effect for the portion of the coast from Ocean Reef to Sebastian Inlet, Florida.

The low level center of Tropical Storm Isaias moved across the eastern part of the Dominican Republic on Thursday.  The middle and upper parts of Isaias skirted along the east coast of Hispaniola.  The various levels of Tropical Storm Isaias appeared to be reconsolidating near the northern coast of the Dominican Republic just to the east of Puerto Plata.  New thunderstorms were forming near the reorganizing center of Isaias.  Those storms were generating upper level divergence which pumped mass away from the tropical storm and allowed the pressure to decrease.  Brands of thunderstorms were wrapping around the eastern and northern sides of the circulation.  The strongest winds were occurring in the portions of those bands over water.  The circulation around Tropical Storm Isaias tightened up on Thursday.  Winds to tropical storm force extended out 240 miles (390 km) to the north and east of Isaias in the parts of the circulation that were over water.

Tropical Storm Isaias will move through an environment favorable for intensification once it moves past Hispaniola.  Isaias will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Isaias will intensify when it moves north of Hispaniola and it could intensify rapidly once an inner core consolidates.  Isaias could intensify to a hurricane on Friday and it could strengthen into a major hurricane during the weekend.

Tropical Storm Isaias will move around the western end of a subtropical high pressure system over the North Atlantic Ocean.  The high will steer Isaias toward the northwest during the next 36 hours.  It will turn the tropical storm more toward the north on the weekend when Isaias reaches the western end of the high pressure system.  On its anticipated track Tropical Storm Isaias will move over the Turks and Caicos by Friday morning.  Isaias will move over the the Bahamas on Friday and it could approach southeast Florida on Saturday.  Tropical Storm Isaias could approach the coast of the Carolinas on Monday.  Tropical Storm Isaias will bring gusty winds and locally heavy rain to the Turks and Caicos and the Bahamas.  Heavy rain could cause flash floods.

Tropical Storm Isaias Drops Heavy Rain on Puerto Rico

Tropical Storm Isaias dropped heavy rain on Puerto Rico on Thursday.  At 8:00 a.m. EDT on Thursday the center of Tropical Storm Isaias was located at latitude 17.6°N and longitude 68.5°w which put it about 105 miles (165 km) east- southeast of Santo Domingo, Dominican Republic.  The center was about 80 miles (130 km) south of Cabo Engano.  Isaias was moving toward the northwest at 20 m.p.h. (32 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 1003 mb.

Tropical Storm Warnings were in effect for Puerto Rico, Culebra, Vieques, the U.S. Virgin Islands, the British Virgin Islands,  the entire coast of the Dominican Republic, Le Mole St. Nicholas, Haiti to the northern border with the Dominican Republic, the Turks and Caicos, the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, the Ragged Islands, Cat Island, the Exumas, Long Island, Rum Cay and San Salvador.  Tropical Storm Watches were in effect for Andros Island, New Providence, Eleuthera, the Abacos, the Berry Islands, Grand Bahama Island and Bimini.

Bands on the eastern side of Tropical Storm Isaias were dropping heavy rain over parts of Puerto Rico on Thursday morning.  Flash Flood Warnings were in effect for parts of the island.  Isaias was also causing winds to tropical storm force in parts in Puerto Rico.  A station at Yabucoa Tanque de Agua reported a sustained wind speed of 46 m.p.h. (74 km/h) and a wind gust to 56 m.p.h. (91 km/h).  A station at Las Mareas reported a sustained wind speed of 3 m.p.h. (69 km/h) and a wind gust of 54 m.p.h. (87 km/h).

The circulation around Tropical Storm Isaias exhibited much more organization on Thursday morning, although the mid-level center did appear to be displaced to the north of the low level center.  There was a center of circulation but the distribution of thunderstorms was asymmetrical.  Most of the stronger thunderstorms were occurring in bands in the eastern side of Tropical Storm Isaias.  Storms near the center of circulation were generating upper level divergence which was pumping mass away from the tropical storm.  Bands in the western half of Isaias consisted primarily of showers and lower clouds.  Northerly winds on that side of the circulation were sinking over the southern part  of Hispaniola and that could have been suppressing the development of thunderstorms in that region.  The circulation around Tropical Storm Isaias was very still very large.  Winds to tropical storm force extended out 415 miles (665 km) on the northern side of Isaias.

Tropical Storm Isaias could weaken when the low level center of circulation moves across the eastern part of the Dominican Republic.  The low level circulation will be disrupted by the terrain but it looks like Isaias will pass east of the tallest mountains on Hispaniola.  The mid-level center of Tropical Storm Isaias appears to be passing very close to the eastern end of Hispaniola.  The middle and upper portions of the circulation are likely to remain intact and a new low level circulation could form north of Hispaniola.  Tropical Storm Isaias will move through an environment favorable for intensification once it moves past Hispaniola.  Isaias will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Isaias is likely to intensify when it moves north of Hispaniola and it could intensify rapidly once a new low level center of circulation develops.

Tropical Storm Isaias will move around the western end of a subtropical high pressure system over the North Atlantic Ocean.  The high will steer Isaias toward the northwest during the next 48 hours.  it will turn the tropical storm more toward the north on the weekend when Isaias reaches the western end of the high pressure system.  On its anticipated track Tropical Storm Isaias will move across the eastern part of the Dominican Republic today.  Isaias will move over the Bahamas on Friday and it could approach southeast Florida on Saturday.  Tropical Storm Isaias will bring gusty winds and locally heavy rain to Puerto Rico, Hispaniola and the Bahamas.  Flash floods could occur.

Tropical Storm Isaias Develops South of Puerto Rico

Tropical Storm Isaias developed south of Puerto Rico on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Isaias was located at latitude 15.8°N and longitude 67.0°W which put it about 155 miles (250 km) south of Ponce, Puerto Rico.  Isaias was moving toward the west-northwest at 20 m.p.h. (32 km/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 1004 mb.

Tropical Storm Warnings were in effect for Puerto Rico, Culebra, Vieques, the U.S. Virgin Islands, the British Virgin Islands, St. Martin, St. Barthelemy, Saba, St. Eustatius, St. Maarten, the entire coast of the Dominican Republic, Le Mole St. Nicholas, Haiti to the northern border with the Dominican Republic, the Turks and Caicos, the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, the Ragged Islands, Cat Island, the Exumas, Long Island, Rum Cay and San Salvador.  Tropical Storm Watches were in effect for Andros Island, New Providence, Eleuthera, the Abacos, the Berry Islands, Grand Bahama Island and Bimini.

Data from a scatterometer onboard a satellite and observations from a buoy south of Puerto Rico indicated that a distinct center of circulation formed within a large low pressure system over the northeastern Caribbean Sea and the National Hurricane Center designated the system as Tropical Storm Isaias.  The center of circulation formed about 150 miles (240 km) south of Puerto Rico on Wednesday night.  More thunderstorms were developing near the newly formed center.  Many of those thunderstorms were southeast of the center.  Storms near the center were generating upper level divergence which pumped mass away from the tropical storm.  Bands of showers and thunderstorms were also located on the northern periphery  of the circulation and the strongest winds were occurring in those bands.  Winds to tropical storm force extended out 300 miles (485 km) to the northeast of the center of circulation.  Winds to tropical storm force also extended out 130 miles (215 km) to the northwest of the center.  The winds south of the center of Isaias were blowing at less than tropical storm force.

Tropical Storm Isaias will move through an environment favorable for intensification during the next 12 hours.  Isaias will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Isaias will get better organized and strengthen during the first half of Thursday.  A portion of the circulation around Isaias will move over Hispaniola later on Thursday.  Mountains on that island will disrupt the circulation and Tropical Storm Isaias will weaken while the center moves over land.

Tropical Storm Isaias will move around the western end of a subtropical high pressure system over the North Atlantic Ocean.  The high will steer Isaias toward the west-northwest on Thursday.  On its anticipated track Tropical Storm Isaias will move across Hispaniola on Thursday.  Isaias will cause gusty winds and it will drop locally heavy rain when it moves over Hispaniola.  Heavy rain could cause flash floods.

Potential Tropical Storm Prompts Warnings for Puerto Rico, Virgin Islands, Leeward Islands

A low pressure system that has the potential to organize into a tropical storm prompted the issuance of Tropical Storm Warnings for Puerto Rico, the Virgin Islands and many of the Leeward Islands on Tuesday morning.  At 11:00 a.m. EDT on Tuesday the center of Potential Tropical Cyclone Nine was located at latitude 13.8°N and longitude 53.7°W which put it about 585 miles (940 km) east-southeast of the Leeward Islands.  It was moving toward the west at 23 m.p.h. (37 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1007 mb.

Tropical Storm Warnings were issued for Puerto Rico, Culebra, Vieques, the U.S. Virgin Islands, Antigua, Barbuda, the British Virgin Islands, Montserrat, St. Kitts, Nevis, Guadeloupe, Martinique, St. Martin, Saba, St. Eustatius, and St. Maarten.

The circulation around Potential Tropical Cyclone Nine was very broad and it stretched from the southwest toward the northeast.  The stronger thunderstorms were occurring in the southwestern and northeastern ends of the circulation.  There were few thunderstorms or bands in the broad middle of the low pressure system.  Winds to tropical storm force extended out 200 miles (320 km) on the northern side of the circulation.  The winds in the southern half of the low pressure system were blowing at less than tropical storm force.

Potential Tropical Cyclone Nine will move through an environment favorable for intensification during the next two days.  It will move over water where the Sea Surface Temperature is near 29°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  The large broad circulation will contribute to a slow, gradual intensification.  If thunderstorms consolidate around a center of circulation and an inner core begins to form, then the system may be designated as a tropical storm.

Potential Tropical Cyclone Nine will move south of a subtropical high pressure system over the North Atlantic Ocean.  The high will steer the potential tropical storm toward the west-northwest during the next several days.  On its anticipated track Potential Tropical Cyclone Nine could approach the Leeward Islands on Wednesday morning.  It could approach the Virgin Islands and Puerto Rico by Wednesday night.  The large circulation means that Potential Tropical Nine will bring a prolonged period of gusty winds.  It could also drop heavy rain and cause flash floods on some islands.

Tropical Storm Douglas Moves Away from Hawaii

A weakening Tropical Storm Douglas moved away from Hawaii on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Douglas was located at latitude 22.9°N and longitude 163.3°W which put it about 200 miles (325 km) east-southeast of French Frigate Shoals.  Douglas was moving toward the west at 18 m.p.h. (30 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 993 mb.

Tropical Storm Douglas weakened on Monday.  An upper level trough west of Hawaii produced southerly winds which blew toward the top of Douglas’ circulation.  Those winds caused strong vertical wind shear.  The wind shear caused former Hurricane Douglas to weaken even though it was moving over water where the Sea Surface Temperature was near 27°C.  The low level center of circulation was surrounded by showers and lower clouds.  The only thunderstorms were occurring on the northern periphery of the tropical storm.  Bands in the other parts of Douglas consisted of showers and lower clouds.  Winds to tropical storm force extended out about 100 miles (160 km) from the center of circulation.

Tropical Storm Douglas will move south of a subtropical high pressure system over the North Pacific Ocean.  The high will steer Douglas toward the west during the next few days.  On its anticipated track Tropical Storm Douglas will move across the International Date Line and over the Western North Pacific Ocean later this week.  The upper level trough will continue to cause vertical wind shear and Douglas will continue to weaken.

Hurricane Douglas Passes Just North of Hawaii

Hurricane Douglas was passing just to the north of the Hawaiian Islands on Sunday night.  At 11:00 p.m. EDT on Sunday night the center of Hurricane Douglas was located at latitude 22.0°N and longitude 157.3°W which put it about 60 miles (95 km) northeast of Honolulu, Hawaii.  Douglas was moving toward the west-northwest at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 989 mb.

Hurricane Warnings were in effect for Oahu, Kauai and Niihau.

The core of Hurricane Douglas exhibited greater organization on Sunday night.  Thunderstorms around the eye at the center of Douglas grew taller as the hurricane moved over warmer water.  Bands of showers and thunderstorms were revolving around the core.  Winds to hurricane force extended out about 40 miles (65 km) from the center of circulation.  Winds to tropical storm force extended out 115 miles (185 km) from the center in the northern half of Hurricane Douglas.  Winds to tropical storm force only extended out about 50 miles (80 km) on the southern side of the circulation.  The stronger winds were remaining north of the Hawaiian Islands.  There were reports of localized minor wind damage on some of the islands.

Hurricane Douglas will move around the south side of a subtropical high pressure system over the North Pacific Ocean.  The high will steer Douglas toward the west-northwest during the next several days.  On its anticipated track the core of Hurricane Douglas will pass north of Oahu.  Scattered minor wind damage could occur on Oahu, Kauai and Niihau.  The southern part of the eyewall could come closer to Kauai and the risk for wind damage is greater there.  Winds blowing uphill could enhance rainfall on Oahu, Kauai and Niihau.  Flash Flood Watches were in effect for those islands.

Hanna’s Heavy Rain Causes Flash Floods in South Texas

Heavy rain dropped by Hurricane Hanna caused flash floods in South Texas on Sunday.  Radar estimates of the rainfall indicated that 10-15 inches (3 to 5 meters) of rain fell on parts of Lower Rio Grande Valley during the passage of former Hurricane Hanna.  A weather station in McAllen, Texas measured 8.24 inches (209 mm) of rain.  Flash Flood Warnings were in effect for West Central Cameron County, Southern Hidalgo, Southwest Jim Hogg County, and Central Zapata County.  The Arroyo Colorado in Harlingen, Texas rose from 5.2 feet (1.6 meters) to 20.72 feet (6.3 meters) and it was still rising.

Rain was still falling over parts of the Lower Rio Grande Valley even though the center of former Hurricane Hanna had moved over northeastern Mexico.  At 5:00 p.m. EDT on Sunday the center of Tropical Depression Hanna was located at latitude 25.6°N and longitude 100.6°W which put it about 35 miles (55 km) west-southwest of Monterrey, Mexico.  Hanna was moving toward the west-southwest 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. (75 km/h).  The minimum surface pressure was 1002 mb.

Hurricane Hanna Makes Landfall on Padre Island

The center of Hurricane Hanna officially made landfall on Padre Island 15 miles (25 km) north of Port Mansfield, Texas at 6:00 p.m. EDT on Saturday.  At 6:00 p.m. EDT on Saturday the center of Hurricane Hanna was located at latitude 26.8°N and longitude 97.4°W which put it 15 miles (25 km) north of Port Mansfield, Texas.  Hanna was moving toward the west-southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 90 m.p.h. (150 km/h) and there were wind gusts to 110 m.p.h. (175 km/h).  The minimum surface pressure was 973 mb.

A Hurricane Warning was in effect for the portion of the coast from Port Mansfield to Port Aransas, Texas.  Tropical Storm Warnings were in effect for the portions of the coast from Barra el Mezquital, Mexico to Port Mansfield and from Port Aransas to Port O’Connor, Texas.

Hurricane Hanna strengthened during Saturday and the maximum sustained wind speed at the time of landfall was 90 m.p.h. (150 km/h).  The minimum pressure decreased to 973 mb during the day.  A circular eye with a diameter of 35 miles (55 km) developed at the center of circulation.  Winds to hurricane force extended out 30 miles (50 km) from the center of Hanna.  Winds to tropical storm force extended out 90 miles from the center of circulation.  A storm surge of up to 6 feet (2 meters) was occurring along the coast of Texas north of where the center made landfall.  There were reports of minor wind damage in Port Mansfield.

Hurricane Hanna will move south of a strengthening high pressure system over the southern U.S.  The high will steer Hanna toward the west-southwest during the next two days.  On its anticipated track the core of Hurricane Hanna will pass north of Brownsville, McAllen and Harlingen, Texas.  The center of Hanna will pass near Monterrey, Mexico on Sunday.  Hurricane Hanna will weaken gradually while it moves inland.  Hanna will drop heavy rain over South Texas and northeast Mexico.  Flash floods will likely occur in parts of the Lower Rio Grande Valley.