Nice Week, Muggy Weekend… Watching Tropics… Tuesday Afternoon Forecast Update – 4pm

Good Tuesday afternoon to you! As of 4pm, conditions are nice across all of west and central Alabama. A batch of high level cirrus clouds have moved over the area, but there is no rain under the clouds. This is in response to a weak upper level disturbance moving across the area. Moisture is starved over Alabama, so don’t expect any rain. The high level clouds will quickly move out tonight. Lows will fall into the lower 60s tonight, with some upper 50s in spots. Much like lastnight, we’ll notice a taste of fall weather this evening and tonight.

Skies will remain partly to mostly cloudy through 7pm, as temperatures fall into the upper 70s to lower 80s. 10pm temperatures will reach the lower 70s. If you have plans outdoors this evening, expect very nice conditions across the area, with no issues with rain or unsettled weather. Skies will gradually clear out tonight as the upper air disturbance moves east of the area. The sharp eastern US trough will remain, so we’ll continue to deal with comfortable conditions through Thursday. Expect mostly sunny skies on Wednesday and Thursday. A surface high to the north of Alabama will keep conditions nice. Highs will warm into the lower 90s on Wednesday, Thursday and Friday, but overnight lows will continue fairly cool. Temperatures will fall into the upper 50s to lower 60s tonight through Wednesday night.

Skies will gradually become partly cloudy again on Friday, Saturday and Sunday. As moisture levels increase, we can expect the risk of a stray storm or two. The chance of rain is  low, so your weekend plans should go on without problems. Highs will remain in the lower 90s, but lows will increase into the upper 60s.

Tropical Storm Isaac has formed in the central Atlantic. That system will continue to move west, then cut northwest over the weekend. There’s a good chance Isaac will impact the southeastern US sometime next week. While most data moves it towards Florida or the Carolinas, we’ll have to watch our coast as well. There’s a low risk of Alabama impacts, but confidence is low for now. Since the system is so far out, changes are likely with the forecast track and strength. It’s a storm worth watching…

Send us your weather pictures! Send them to weather@wvuatv.com. Also, look us up on facebook and twitter. Like us on facebook by searching facebook.com/wvuaweather or WVUA-TV Weather. You can find us on twitter by searching weather@wvuatv.comor WVUA-TV Weather. Great way to get weather updates! Plus, facebook is a great way to send us weather pictures. Simply tag us!

Join us live on WVUA-TV weekdays at 4, 5, 6 and 10 pm and weekends at 10pm for the very latest on your news, weather and sports.

Richard Scott

WVUA Chief Meteorologist

rscott@wvuatv.com

 

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Tropical Storm Isaac Is Born…Tuesday Update 4pm Update

Tropical Storm Isaac has formed this afternoon as it tracks westward. There’s a good chance Isaac will continue to develop and become a hurricane later this week. The big questions come into play on Friday, Saturday and Sunday. Will Isaac move over the very mountainous terrain of Hispaniola and Cuba, or does it stay just to the south? Interaction with land will cause the system to weaken over the weekend, but if the storm stays south of the big islands, the storm will become a powerful hurricane. The track from the National Hurricane Center has the storm tracking across Cuba on Saturday and Sunday. Here’s the latest from the National Hurricane Center:

AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE DEPRESSION REPORTED 44-KT FLIGHT-LEVEL WINDS AT 1000 FT TO THE NORTHEAST OF THE CENTER…AS WELL AS BIAS-CORRECTED SFMR SURFACE WINDS ESTIMATES OF 35 KT.  THE MINIMUM CENTRAL PRESSURE WAS NEAR 1005 MB.  BASED ON THESE DATA…THE DEPRESSION IS UPGRADED TO TROPICAL STORM ISAAC.  DESPITE THE UPGRADE…THE CYCLONE REMAINS SOMEWHAT DISORGANIZED…WITH THE LOW-LEVEL CENTER PARTLY EXPOSED TO THE NORTH OF THE MAIN CONVECTIVE MASS.

THE LOW-LEVEL CENTER HAS NUDGED NORTHWARD DURING THE AFTERNOON…BUT THE LONGER TERM MOTION IS 275/15.  ISAAC REMAINS SOUTH OF A DEEP-LAYER SUBTROPICAL RIDGE THAT IS FORECAST TO REMAIN INTACT FOR THE NEXT 72 HR…WHICH SHOULD KEEP THE CYCLONE MOVING GENERALLY WESTWARD AS SHOWN BY THE TIGHTLY CLUSTERED TRACK MODEL GUIDANCE. AFTER THAT…THE GLOBAL MODELS CONTINUE TO FORECAST A SHORTWAVE TROUGH TO DIG SOUTHWARD OVER THE SOUTHEASTERN U.S. AND THE GULF OF MEXICO…WHICH IS EXPECTED TO WEAKEN THE RIDGE ACROSS FLORIDA AND THE BAHAMAS. THIS SHOULD ALLOW THE CYCLONE TO TURN WEST- NORTHWESTWARD AND SLOW DOWN OVER THE NORTH-CENTRAL CARIBBEAN SEA AND THE GREATER ANTILLES.  THE GUIDANCE HAS BECOME LESS CONSISTENT SINCE THE PREVIOUS ADVISORY.  WHILE THE CENTER OF THE GUIDANCE ENVELOPE HAS CHANGED LITTLE…THE ECMWF HAS SHIFTED WELL TO THE LEFT OF ITS PREVIOUS FORECAST AND NOW CALLS FOR A WESTWARD MOTION AFTER ISAAC PASSES HISPANIOLA.  THE GFS ENSEMBLES HAVE ALSO SHIFTED WESTWARD…ALTHOUGH THE ENSEMBLE MEAN STILL LIES NEAR THE FORECAST TRACK.  THE NEW TRACK IS NUDGED A LITTLE TO THE NORTH OF THE PREVIOUS TRACK BEFORE 72 HR…AND THEN IS NUDGED A LITTLE TO THE RIGHT THEREAFTER.  THE TRACK FORECAST AFTER 72 HR LIES NEAR THE LEFT EDGE OF THE GUIDANCE ENVELOPE…WITH ONLY THE ECMWF WELL TO THE LEFT OF THE CURRENT FORECAST.  USERS ARE CAUTIONED THAT FIVE-DAY TRACK ERRORS AVERAGE ABOUT 225 N MI.

ISAAC CONTINUES TO EXPERIENCE SOME LIGHT NORTHEASTERLY VERTICAL WIND SHEAR…AND IT MAY NOT YET HAVE FULLY MIXED OUT THE DRY AIR THAT HAS BEEN AFFECTING IT.  THE SHEAR IS FORECAST TO DIMINISH IN 12-24 HR…WHICH SHOULD ALLOW SOME STRENGTHENING.  THAT BEING SAID…THE GFDL AND HWRF MODELS HAVE BACKED OFF ON THEIR FORECASTS OF INTENSIFICATION…AND THE SHIPS AND LGEM MODELS ARE ALSO LESS BULLISH.  BASED ON THIS…THE NEW INTENSITY FORECAST SHOWS A LITTLE LESS STRENGTHENING THAN THE PREVIOUS ADVISORY.  THE INTENSITY FORECAST AFTER 72 HR HAS AGAIN BEEN REDUCED DUE TO THE FORECAST TRACK SHOWING INCREASED LAND INTERACTION WITH HISPANIOLA AND CUBA.

Send us your weather pictures! Send them to weather@wvuatv.com. Also, look us up on facebook and twitter. Like us on facebook by searching facebook.com/wvuaweather or WVUA-TV Weather. You can find us on twitter by searching weather@wvuatv.comor WVUA-TV Weather. Great way to get weather updates! Plus, facebook is a great way to send us weather pictures. Simply tag us!

Join us live on WVUA-TV weekdays at 4, 5, 6 and 10 pm and weekends at 10pm for the very latest on your news, weather and sports.

Richard Scott

WVUA Chief Meteorologist

rscott@wvuatv.com

 

Tropical Depression # 9 Forms…US Impacts Likely… One To Watch Close! – Tuesday Morning Update 9am

Here’s the 5am update from the National Hurricane Center on Tropical Depression # 9. It’s still a good 6 days or so out from a US landfall, so there’s time for the path to change some. It’s a storm that needs to be watched for sure. I can’t tell you where it will make landfall or how strong it will be at this point because it’s still so far out. As the next few days move along, we’ll know more and more about this feature. Here’s an update from the National Hurricane Center.

TROPICAL DEPRESSION NINE DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092012
500 AM AST TUE AUG 21 2012

THE LARGE LOW PRESSURE SYSTEM THAT HAS BEEN TRAVERSING THE CENTRAL TROPICAL ATLANTIC FOR THE PAST FEW DAYS HAS ACQUIRED ENOUGH ORGANIZED DEEP CONVECTION NEAR THE CENTER TO BE CLASSIFIED AS A TROPICAL DEPRESSION. THE INITIAL INTENSITY OF 30 KT IS BASED ON A SATELLITE INTENSITY ESTIMATE OF T2.0/30 KT FROM TAFB AND T1.5/25 KT FROM SAB. SINCE THE 0600 UTC SATELLITE CLASSIFICATIONS… CONVECTION HAS CONTINUED TO INCREASE WITH SOME CLOUD TOP TEMPERATURES COLDER THAN -80C NOTED JUST SOUTHWEST OF THE LOW-LEVEL CENTER.

THE INITIAL MOTION ESTIMATE IS 270/17 KT. THE DEPRESSION IS LOCATED SOUTH OF A DEEP-LAYER SUBTROPICAL RIDGE THAT IS FORECAST TO REMAIN INTACT FOR THE NEXT FOUR DAYS…WHICH SHOULD KEEP THE CYCLONE MOVING IN A WESTWARD TO WEST-NORTHWESTWARD DIRECTION THROUGH 96 HOURS. BY DAY 5…HOWEVER…THE GLOBAL MODELS ARE FORECASTING A SHORTWAVE TROUGH TO DIG SOUTHWARD OVER THE SOUTHEASTERN U.S. AND THE GULF OF MEXICO…WHICH IS EXPECTED TO WEAKEN THE RIDGE ACROSS FLORIDA AND THE BAHAMAS. THIS SHOULD ALLOW THE CYCLONE TO TURN NORTHWESTWARD AND SLOW DOWN ACROSS THE NORTH-CENTRAL CARIBBEAN SEA. THE OFFICIAL FORECAST TRACK IS CLOSE TO THE MULTI-MODEL CONSENSUS TVCA…WHICH IS A COMPROMISE OF THE FASTER GFS MODEL AND SLOWER ECMWF MODEL.

OTHER THAN SOME MODEST NORTHEASTERLY VERTICAL WIND SHEAR FOR THE NEXT 24 HOURS OR SO…ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE QUITE FAVORABLE FOR INTENSIFICATION TO OCCUR. DURING DAYS 2-3…THE VERTICAL SHEAR IS FORECAST TO BE THE WEAKEST AND WATER TEMPERATURES THE WARMEST…AND THAT IS WHEN THE MOST SIGNIFICANT STRENGTHENING SHOULD OCCUR. AT DAYS 4 AND 5…POSSIBLE INTERACTION WITH LAND MASSES OF HAITI AND CUBA…RESPECTIVELY…IS THE PRIMARY REASON  FOR THE LEVELING OFF IN THE INTENSITY. THE OFFICIAL INTENSITY
FORECAST CLOSELY FOLLOWS THE TREND OF…BUT IS LOWER THAN…THE SHIPS AND LGEM INTENSITY MODELS…ESPECIALLY AT DAYS 3 AND 4.

AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL INVESTIGATE THE CYCLONE THIS AFTERNOON.

Send us your weather pictures! Send them to weather@wvuatv.com. Also, look us up on facebook and twitter. Like us on facebook by searching facebook.com/wvuaweather or WVUA-TV Weather. You can find us on twitter by searching weather@wvuatv.comor WVUA-TV Weather. Great way to get weather updates! Plus, facebook is a great way to send us weather pictures. Simply tag us!

Join us live on WVUA-TV weekdays at 4, 5, 6 and 10 pm and weekends at 10pm for the very latest on your news, weather and sports.

Richard Scott

WVUA Chief Meteorologist

rscott@wvuatv.com