Thursday Night Forecast Discussion – 11:25 p.m.

Only very isolated rain chances expected through the weekend as the ridge begins to slowly weaken starting Friday. With mostly clear skies overnight still one more very nice night tonight into early Friday then we will start to see those nighttime readings begin to creep back up again with the weakening ridge and slowly increasing moisture.

Tropical systems are never boring or easy to forecast as Isaac continues to challenge. From 12z Sunday onward models diverge on our outcome scenarios as 12z Euro is trending back toward yesterday`s 12z bringing the system back to the western end of the envelope toward Texas/Louisiana coast by Thursday keeping the upper ridge around longer. The GFS continues to weaken the upper ridge allowing Isaac to push northward toward the Florida panhandle Tuesday night into Wednesday morning. However, the GFS has trended slightly further west, possibly trending toward the Euro eventually but still quite a bit uncertainty in the forecast. Since this track affects our rain/wind/temperatures it is likely we will have cooler temps next week. There is still too much uncertainty with the track to go very high with the rain chances just yet due to track and timing. This is something we are keeping a close eye on and will update frequently. Stay tuned!

Daniel Sparkman
dsparkman@wvuatv.com
WVUA Weather

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Tropical Storm Isaac Update – Thursday 11 p.m.

We are now very confident that West Alabama will feel the effects of Isaac. The model trend now takes Isaac as a category 1 hurricane into the northern gulf coast. The official track from the National Hurricane Center takes Isaac right into Mobile Bay. If this turns out to be the case, here in West Alabama we will likely have the possibility of heavy rainfall and some isolated tornadoes. We are going to continue to follow this developing weather story over the weekend and have a much better idea come Sunday and into Monday as to where exactly Isaac will make landfall. Below is the latest update from the National Hurricane Center.

TROPICAL STORM ISAAC ADVISORY NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092012
1100 PM AST THU AUG 23 2012

…ISAAC EXPECTED TO BE NEAR OR OVER HISPANIOLA TOMORROW ALONG WITH HEAVY RAINS AND FLOODING…

SUMMARY OF 1100 PM AST…0300 UTC…INFORMATION
———————————————–
LOCATION…16.7N 68.7W
ABOUT 145 MI…235 KM SSE OF SANTO DOMINGO DOMINICAN REPUBLIC
MAXIMUM SUSTAINED WINDS…45 MPH…75 KM/H
PRESENT MOVEMENT…WNW OR 290 DEGREES AT 18 MPH…30 KM/H
MINIMUM CENTRAL PRESSURE…1001 MB…29.56 INCHES

WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY…

THE HURRICANE WARNING FOR HAITI HAS BEEN CHANGED TO A TROPICAL STORM WARNING AND A HURRICANE WATCH.

THE GOVERNMENT OF CUBA HAS ISSUED A TROPICAL STORM WARNING FOR THE CUBAN PROVINCES OF CAMAGUEY…LAS TUNAS…GRANMA…HOLGUIN…SANTIAGO DE CUBA…AND GUANTANAMO.

THE GOVERNMENT OF CUBA HAS ISSUED A TROPICAL STORM WATCH FOR THE CUBAN PROVINCES OF CIEGO DE AVILA…SANCTI SPIRITUS…AND VILLA CLARA.

THE TROPICAL STORM WARNINGS FOR PUERTO RICO…VIEQUES…CULEBRA…AND THE U.S. VIRGIN ISLANDS HAVE BEEN DISCONTINUED.

THE GOVERNMENT OF ANTIGUA AND BARBUDA HAS DISCONTINUED THE TROPICAL STORM WARNING FOR THE BRITISH VIRGIN ISLANDS.

THE GOVERNMENT OF THE BAHAMAS HAS ISSUED A TROPICAL STORM WATCH FOR ANDROS ISLAND AND THE CENTRAL BAHAMAS INCLUDING CAT ISLAND…THE EXUMAS…LONG ISLAND…RUM CAY…AND SAN SALVADOR.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A HURRICANE WATCH IS IN EFFECT FOR…
* HAITI

A TROPICAL STORM WARNING IS IN EFFECT FOR…
* DOMINICAN REPUBLIC
* HAITI
* CUBAN PROVINCES OF CAMAGUEY…LAS TUNAS…GRANMA…HOLGUIN…SANTIAGO DE CUBA…AND GUANTANAMO
* SOUTHEASTERN BAHAMAS INCLUDING THE ACKLINS…CROOKED ISLAND…LONG CAY…THE INAGUAS…MAYAGUANA…AND THE RAGGED ISLANDS
* TURKS AND CAICOS ISLANDS

A TROPICAL STORM WATCH IS IN EFFECT FOR…
* CUBAN PROVINCES OF CIEGO DE AVILA…SANCTI SPIRITUS…AND VILLA CLARA
* ANDROS ISLAND AND THE CENTRAL BAHAMAS INCLUDING CAT ISLAND…THE EXUMAS…LONG ISLAND…RUM CAY…AND SAN SALVADOR

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA…IN THIS CASE WITHIN THE NEXT 24 TO 36 HOURS.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA…GENERALLY WITHIN 48 HOURS.

INTERESTS IN JAMAICA…THE REMAINDER OF CUBA…THE REMAINDER OF THE BAHAMAS…SOUTH FLORIDA…AND THE FLORIDA KEYS SHOULD MONITOR THE PROGRESS OF ISAAC.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED STATES…INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS…PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE THE UNITED STATES…PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.

DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 1100 PM AST…0300 UTC…THE CENTER OF TROPICAL STORM ISAAC WAS LOCATED NEAR LATITUDE 16.7 NORTH…LONGITUDE 68.7 WEST. ISAAC IS MOVING TOWARD THE WEST-NORTHWEST NEAR 18 MPH…30 KM/H…AND A WEST-NORTHWEST TO NORTHWEST MOTION AT A SLIGHTLY SLOWER FORWARD SPEED IS EXPECTED OVER THE NEXT COUPLE OF DAYS.  ON THE FORECAST TRACK…THE CENTER OF ISAAC WILL BE NEAR OR OVER HISPANIOLA ON FRIDAY…AND MOVE NEAR OR OVER SOUTHEASTERN CUBA ON SATURDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH…75 KM/H…WITH HIGHER GUSTS.  SOME STRENGTHENING IS FORECAST WHILE THE CENTER REMAINS OVER WATER.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 185 MILES…295 KM FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB…29.56 INCHES.

HAZARDS AFFECTING LAND
———————-
WIND…TROPICAL STORM CONDITIONS ARE EXPECTED OVER PORTIONS OF THE DOMINICAN REPUBLIC AND HAITI ON FRIDAY…WITH HURRICANE CONDITIONS POSSIBLE OVER PORTIONS OF HAITI.  TROPICAL STORM CONDITIONS ARE EXPECTED OVER THE SOUTHEASTERN BAHAMAS AND THE TURKS AND CAICOS ISLANDS BY LATE FRIDAY.  TROPICAL STORM CONDITIONS ARE EXPECTED OVER EASTERN CUBA BY LATE FRIDAY OR EARLY SATURDAY.  TROPICAL STORM CONDITIONS ARE POSSIBLE OVER CENTRAL CUBA…THE CENTRAL BAHAMAS…AND ANDROS ISLAND BY SATURDAY.

RAINFALL…TOTAL RAINFALL ACCUMULATIONS OF 8 TO 12 INCHES…WITH MAXIMUM AMOUNTS OF 20 INCHES…ARE POSSIBLE OVER HISPANIOLA.  THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. TOTAL RAIN ACCUMULATIONS OF 2 TO 4 INCHES…WITH MAXIMUM AMOUNTS OF 6 INCHES OVER HIGHER TERRAIN…ARE POSSIBLE OVER PUERTO RICO AND THE VIRGIN ISLANDS.  TOTAL RAIN ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE OVER THE SOUTHEASTERN BAHAMAS.

STORM SURGE…A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 2 TO 4 FEET ABOVE NORMAL TIDE LEVELS IN AREAS OF ONSHORE WINDS ALONG THE COAST OF HISPANIOLA.  NEAR THE COAST…THE SURGE WILL BE
ACCOMPANIED BY DANGEROUS WAVES.  A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 1 TO 3 FEET ABOVE NORMAL TIDE LEVELS IN AREAS OF ONSHORE WINDS ALONG THE COAST WITHIN THE REMAINING TROPICAL STORM WARNING AREA.

SURF…DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL AFFECT THE LEEWARD ISLANDS…VIRGIN ISLANDS…PUERTO RICO…HISPANIOLA…THE SOUTHEASTERN BAHAMAS…AND THE TURKS AND CAICOS DURING THE NEXT COUPLE OF DAYS.  PLEASE CONSULT PRODUCTS FROM YOUR LOCAL WEATHER OFFICE FOR MORE INFORMATION.

NEXT ADVISORY
————-
NEXT INTERMEDIATE ADVISORY…200 AM AST.
NEXT COMPLETE ADVISORY…500 AM AST.

Daniel Sparkman
dsparkman@wvuatv.com
WVUA Weather

Tropical Storm Isaac Update – Thursday 1 p.m.

TROPICAL STORM ISAAC INTERMEDIATE ADVISORY NUMBER  10A
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092012
200 PM AST THU AUG 23 2012

…CENTER OF ISAAC NOW MOVING WEST-NORTHWESTWARD SOUTH OF PUERTO RICO…

SUMMARY OF 200 PM AST…1800 UTC…INFORMATION
———————————————-
LOCATION…16.0N 66.4W
ABOUT 165 MI…255 KM S OF SAN JUAN PUERTO RICO
ABOUT 275 MI…445 KM SE OF SANTO DOMINGO DOMINICAN REPUBLIC
MAXIMUM SUSTAINED WINDS…40 MPH…65 KM/H
PRESENT MOVEMENT…WNW OR 285 DEGREES AT 15 MPH…24 KM/H
MINIMUM CENTRAL PRESSURE…1003 MB…29.62 INCHES

WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY…

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A HURRICANE WARNING IS IN EFFECT FOR…
* SOUTH COAST OF DOMINICAN REPUBLIC FROM ISLA SAONA WESTWARD TO THE HAITI-DOMINICAN REPUBLIC SOUTHERN BORDER
* HAITI

A TROPICAL STORM WARNING IS IN EFFECT FOR…
* BRITISH VIRGIN ISLANDS
* PUERTO RICO…VIEQUES…CULEBRA…AND THE U.S. VIRGIN ISLANDS
* NORTH COAST OF DOMINICAN REPUBLIC FROM THE HAITI-DOMINICAN REPUBLIC NORTHERN BORDER EASTWARD TO NORTH OF ISLA SAONA

A TROPICAL STORM WATCH IS IN EFFECT FOR…
* SOUTHEASTERN BAHAMAS INCLUDING THE ACKLINS…CROOKED ISLAND…LONG CAY…THE INAGUAS…MAYAGUANA…AND THE RAGGED ISLANDS AND THE TURKS AND CAICOS ISLANDS

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA.  PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA…GENERALLY WITHIN 48 HOURS.

INTERESTS IN CUBA…JAMAICA…AND ELSEWHERE IN THE BAHAMAS SHOULD MONITOR THE PROGRESS OF ISAAC.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED STATES…PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE THE UNITED STATES…PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.

DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 200 PM AST…1800 UTC…THE CENTER OF TROPICAL STORM ISAAC WAS LOCATED NEAR LATITUDE 16.0 NORTH…LONGITUDE 66.4 WEST. ISAAC IS NOW MOVING TOWARD THE WEST-NORTHWEST NEAR 15 MPH…24 KM/H…AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE THROUGH SATURDAY.  ON THE FORECAST TRACK…THE CENTER OF ISAAC WILL CONTINUE TO PASS SOUTH OF PUERTO RICO TODAY…AND BE NEAR THE SOUTH COAST OF THE DOMINICAN REPUBLIC AND HAITI ON FRIDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 40 MPH…65 KM/H…WITH HIGHER GUSTS.  STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS…AND ISAAC COULD BECOME A HURRICANE AS IT NEARS THE DOMINICAN REPUBLIC AND HAITI.  AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS CURRENTLY INVESTIGATING ISAAC.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140 MILES…220 KM FROM THE CENTER.  NOAA BUOY 42060 RECENTLY REPORTED 1-MINUTE MEAN WINDS OF 40 MPH…65 KM/HR…AND A WIND GUST OF 47 MPH…76 KM/HR.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB…29.62 INCHES.

HAZARDS AFFECTING LAND
———————-
WIND…TROPICAL STORM CONDITIONS ARE SUBSIDING OVER THE LEEWARD ISLANDS.  TROPICAL STORM CONDITIONS ARE EXPECTED OVER PORTIONS OF PUERTO RICO AND THE U.S. AND BRITISH VIRGIN ISLANDS THIS AFTERNOON. HURRICANE CONDITIONS ARE EXPECTED OVER PORTIONS OF THE DOMINICAN REPUBLIC BY FRIDAY…AND OVER PORTIONS OF HAITI FRIDAY OR FRIDAY NIGHT.  TROPICAL STORM CONDITIONS ARE POSSIBLE OVER THE SOUTHEASTERN BAHAMAS AND THE TURKS AND CAICOS ISLANDS BY LATE FRIDAY.

RAINFALL…TOTAL RAINFALL ACCUMULATIONS OF 8 TO 12 INCHES…WITH MAXIMUM AMOUNTS OF 20 INCHES…ARE POSSIBLE OVER HISPANIOLA. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.  TOTAL RAIN ACCUMULATIONS OF 2 TO 4 INCHES…WITH MAXIMUM AMOUNTS OF 10 INCHES OVER HIGHER TERRAIN…ARE POSSIBLE OVER PUERTO RICO AND THE VIRGIN ISLANDS.  TOTAL RAIN ACCUMULATIONS OF 4 TO 8 INCHES ARE POSSIBLE OVER THE NORTHERN WINDWARD ISLANDS AND THE LEEWARD ISLANDS.

STORM SURGE…A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 3 TO 5 FEET ABOVE NORMAL TIDE LEVELS IN AREAS OF ONSHORE WINDS ALONG THE COAST OF HISPANIOLA.  A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 1 TO 3 FEET ABOVE NORMAL TIDE LEVELS IN THE NORTHERN LEEWARD ISLANDS…PUERTO RICO…AND THE U.S. AND BRITISH VIRGIN ISLANDS.  NEAR THE COAST…THE SURGE WILL BE ACCOMPANIED BY DANGEROUS WAVES.

SURF…DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL AFFECT THE WINDWARD ISLANDS…LEEWARD ISLANDS…VIRGIN ISLANDS…AND PUERTO RICO DURING THE NEXT COUPLE OF DAYS.  PLEASE CONSULT PRODUCTS FROM YOUR LOCAL WEATHER OFFICE FOR MORE INFORMATION.

NEXT ADVISORY
————-
NEXT COMPLETE ADVISORY…500 PM AST.

Daniel Sparkman
dsparkman@wvuatv.com
WVUA Weather