10PM Friday Update on Tropical Storm Ernesto… Brand New Tropical Depression # 6 Forms…
August 3, 2012 Leave a comment
TROPICAL STORM ERNESTO DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012
1100 PM AST FRI AUG 03 2012
CONVECTION HAS BECOME MORE CONCENTRATED NEAR THE CENTER OF ERNESTO DURING THE PAST SEVERAL HOURS. HOWEVER…SATELLITE INTENSITY ESTIMATES AND AN ABBREVIATED HURRICANE HUNTER MISSION SUGGEST THAT THIS HAS NOT YET RESULTED IN INTENSIFICATION. THE INITIAL INTENSITY REMAINS 45 KT…AND THE CENTRAL PRESSURE OF 1003 MB IS BASED ON EXTRAPOLATION OF THE HURRICANE HUNTER DATA. ANALYSIS FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SUGGEST THAT VERTICAL WIND SHEAR IS DECREASING OVER ERNESTO…AND THE OUTFLOW HAS IMPROVED IN THE WESTERN SEMICIRCLE.
THE INITIAL MOTION IS 275/16…A LITTLE SLOWER THAN BEFORE. A STRONG LOW/MID-LEVEL SUBTROPICAL RIDGE TO THE NORTH OF ERNESTO SHOULD KEEP THE CYCLONE ON A GENERAL WESTWARD TRACK FOR THE NEXT 36-48 HR…AND THE NEW FORECAST TRACK IS SIMILAR TO THE OLD TRACK DURING THIS PERIOD. AFTER THAT TIME…THE TRACK FORECAST BECOMES LOWER CONFIDENCE. THE GLOBAL MODELS FORECAST A DEVELOPING MID/ UPPER-LEVEL TROUGH OVER THE EASTERN UNITED STATES FROM 72-120 HR… WHICH IS EXPECTED TO CAUSE A WEAKNESS IN THE RIDGE OVER THE THE NORTHERN GULF OF MEXICO AND THE ADJACENT LAND AREAS. THE GFDL… UKMET…AND NOGAPS MODELS RESPOND TO THIS BY FORECASTING ERNESTO TO MOVE NORTHWESTWARD NEAR THE YUCATAN CHANNEL INTO THE SOUTHERN GULF OF MEXICO. ON THE OTHER HAND…THE ECMWF AND GFS FORECAST ERNESTO TO BE TOO FAR SOUTH TO RESPOND TO THE WEAKNESS…AND THUS SHOW THE CYCLONE MOVING INLAND OVER THE SOUTHERN YUCATAN PENINSULA OR CENTRAL AMERICA. BASED ON THE PREMISE THAT ERNESTO WILL BE FAR ENOUGH NORTH AND STRONG ENOUGH TO RESPOND TO THE WEAKNESS…THE LATTER PART OF THE NEW FORECAST TRACK IS NUDGED A LITTLE TO THE NORTH OF THE PREVIOUS FORECAST.
THE INTENSITY GUIDANCE REMAINS VERY DIVERGENT. THE STATISTICAL- DYNAMICAL MODELS FORECAST SIGNIFICANT INTENSIFICATION…WITH THE LGEM CALLING FOR ERNESTO TO BECOME A MAJOR HURRICANE IN 96 HR. THE DYNAMICAL MODELS OFFER A DISSENTING VIEW…WITH THE GFDL AND HWRF PREDICTING LITTLE CHANGE IN STRENGTH UNTIL ABOUT 96 HR. IN ADDITION…THE ECMWF FORECASTS ERNESTO TO REMAIN VERY WEAK. IT IS UNCLEAR WHAT ARE THE NEGATIVE FACTORS THAT THE DYNAMICAL MODELS ARE SEEING…SINCE THE SHEAR IS FORECAST TO BE LIGHT AFTER 24 HR AND THE SEA SURFACE TEMPERATURES ARE VERY WARM. THE NEW INTENSITY FORECAST SHOWS A LITTLE MORE INTENSIFICATION THAN THE PREVIOUS\ FORECAST THROUGH 48 HR. AFTER THAT…IT IS THE SAME AS THE PREVIOUS FORECAST DUE TO THE DIVERGENT GUIDANCE.
INTERESTS IN JAMAICA SHOULD MONITOR THE PROGRESS OF ERNESTO…AS A TROPICAL STORM WATCH COULD BE REQUIRED FOR PORTIONS OF THE ISLAND ON SATURDAY.
Below is the update on newly formed Tropical Depression # 6…..
TROPICAL DEPRESSION SIX DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062012
1100 PM AST FRI AUG 03 2012
THE TROPICAL WAVE WHICH EMERGED FROM WEST AFRICA YESTERDAY QUICKLY DEVELOPED A WELL-DEFINED CENTER ALONG WITH SUBSTANTIAL DEEP CONVECTION TODAY. THE COLD CLOUD TOPS ARE MAINLY SOUTH OF THE CENTER DUE TO THE IMPINGING EFFECTS OF MODERATE NORTHEASTERLY VERTICAL SHEAR. DVORAK CURRENT INTENSITY NUMBERS AT 00Z WERE 2.0 FROM TAFB AND 1.5 FROM SAB…AND THE CONVECTIVE STRUCTURE HAS PERSISTED AND IMPROVED SLIGHTLY SINCE THAT TIME. THUS ADVISORIES ARE BEING INITIATED ON TROPICAL DEPRESSION SIX. IT APPEARS THAT THE GENESIS OF THIS CYCLONE WAS AIDED BY THE INTERACTION OF THE WESTWARD MOVING TROPICAL WAVE WITH AN EASTWARD MOVING CONVECTIVELY-COUPLED KELVIN WAVE AS DEPICTED BY ANALYSES FROM SUNY-ALBANY.
MOVEMENT OF THE CYCLONE IS CURRENTLY 290 DEGREES AT 14 KT…AS THE SYSTEM IS PRIMARILY BEING STEERED BY A MID TO UPPER LEVEL RIDGE NORTH OF THE CYCLONE. FINDING THE INITIAL POSITION WAS SUBSTANTIALLY AIDED BY SOME SSMI AND WINDSAT MICROWAVE IMAGERY FROM NRL. THE TROPICAL CYCLONE SHOULD CONTINUE MOVING WEST- NORTHWEST FOR THE NEXT DAY OR TWO IN THE DEEP LAYER FLOW. AFTER ABOUT TWO DAYS…IT IS ANTICIPATED THAT THE CYCLONE WILL BE WEAKENING AND THUS ADVECTED ALONG WESTWARD BY THE LOWER TROPOSPHERIC WINDS. THE FORECAST TRACK FOLLOWS CLOSELY THE TCVA CONSENSUS OF THE DYNAMICAL MODELS.
WHILE THE CYCLONE UNDERWENT GENESIS RATHER QUICKLY TODAY…IT MAY BE THAT THE SYSTEM WILL NOT DEVELOP MUCH FURTHER. CURRENTLY THE CYCLONE IS BEING AFFECTED BY MODERATE NORTHEASTERLY VERTICAL SHEAR. WHILE THIS SHOULD DIMINISH IN ABOUT A DAY…THE COMBINATION OF ONLY LUKEWARM SEA SURFACE TEMPERATURES AND A FAIRLY DRY STABLE ATMOSPHERE MAY ALLOW THE CYCLONE TO PEAK ONLY AS A LOW-END TROPICAL STORM. AFTER ABOUT TWO DAYS…THE SYSTEM SHOULD BE WEAKENING AND IT MAY NO LONGER BE A TROPICAL CYCLONE BY DAY FOUR OR FIVE AS SUGGESTED BY THE GLOBAL AND REGIONAL HURRICANE MODELS. THE INTENSITY FORECAST IS A BLEND OF THE STATISTICAL LGEM AND SHIPS MODELS AND THE DYNAMICAL GFDL AND HWRF MODELS…WITH A BIT MORE EMPHASIS ON THE LATTER.
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Source: National Hurricane Center
