[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 080000
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT MAY 07 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS ALONG 08N13W 03N24W 02N40W 03N51W. SCATTERED
MODERATE TO STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE OF A
LINE FROM 05N13W TO 05N20W. SCATTERED MODERATE CONVECTION IS
WITHIN 180 NM S OF THE ITCZ AXIS BETWEEN 27W AND 30W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR SATELLITE IMAGERY INDICATES STRONG WESTERLY ZONAL
FLOW ALOFT OVER THE GULF THIS EVENING WHICH IS PROMOTING MOSTLY
FAIR WEATHER ACROSS THE BASIN. A DISSIPATING STATIONARY FRONT IS
BECOMING MORE DIFFUSE. THIS FRONT REACHES FROM JUST S OF PALM
BEACH FLORIDA TO JUST S OF FORT MYERS FLORIDA WESTWARD INTO THE
E GULF NEAR 25N85W CONTINUING NW TO NEAR 27N90W. VISIBLE
SATELLITE IMAGERY SHOWS THAT ISOLATED SHOWERS ARE POSSIBLE
WITHIN 30 NM EITHER SIDE OF THE FRONTAL BOUNDARY. FLORIDA STATE
WSR-88D RADAR MOSAIC INDICATES ISOLATED SHOWERS AND TSTMS JUST
S OF THE FRONT OVER FLORIDA BEING ENHANCED BY CONVERGING SEA
BREEZE BOUNDARIES. THIS ACTIVITY SHOULD WEAKEN WITH THE LOSS OF
DAYTIME HEATING AFTER SUNSET. 1017 MB HIGH PRES IS IN THE
PROCESS OF DEVELOPING IN THE NE GULF NEAR 28N86W WITH A FORMING
RIDGE AXIS EXTENDING WESTWARD TO THE COAST OF TEXAS NEAR
MATAGORDA BAY. E TO SE WINDS FLOW AROUND THE SURFACE RIDGE.
THIS OVERALL PATTERN IS FORECAST TO PERSIST THROUGH THE
REMAINDER OF THE WEEKEND AS WELL AS THROUGH MUCH OF NEXT WEEK AS
THE SURFACE HIGH REMAINS NEARLY STATIONARY OVER THE NE GULF
WATERS. SOUTHERLY RETURN FLOW WILL INCREASE TO UP TO 20 KT
BEGINNING SUN OVER THE FAR WESTERN GULF WHERE THE PRESSURE
GRADIENT WILL BE THE TIGHTEST.

CARIBBEAN SEA...
THE MAJORITY OF THE CARIBBEAN SEA BASIN IS UNDER THE INFLUENCE
OF UPPER LEVEL RIDGING WHICH EXTENDS FROM NEAR TRINIDAD NW TO
THE YUCATAN PENINSULA. WATER VAPOR SATELLITE IMAGERY INDICATES
DRY AIR AND SUBSIDENCE N OF 16N ON THE NORTHERN PERIPHERY OF THE
RIDGING ALOFT. THIS IS RESULTING IN MOSTLY CLEAR SKIES AND FAIR
CONDITIONS ACROSS THAT AREA THIS EVENING ALTHOUGH A FEW
LOW-TOPPED ISOLATED SHOWERS ARE OCCURRING FROM SOUTHWESTERN
HISPANIOLA TO JAMAICA WITH ADDITIONAL ISOLATED ACTIVITY IN THE
GULF OF HONDURAS. FARTHER EAST...TOTAL PRECIPITABLE WATER
IMAGERY SHOWS INCREASING VALUES OF LOW-LEVEL MOISTURE BEING
ADVECTED ACROSS THE LESSER ANTILLES THIS EVENING. THIS EAST-WEST
BAND OF MOISTURE...MOST LIKELY REMNANT FRONTAL MOISTURE...IS
GENERATING WIDELY SCATTERED SHOWERS WITHIN 120 NM EITHER SIDE OF
A LINE FROM 16N58W TO 15N69W. OTHERWISE...EASTERLY TRADES
CONTINUE ACROSS THE BASIN IN THE RANGE OF 15-20 KT S OF 17N AND
10-15 KT N OF 17N. THESE CONDITIONS WILL NOT CHANGE MUCH THROUGH
THE EARLY PART OF THE UPCOMING WEEK. ISOLATED TO SCATTERED
SHOWERS AND TSTMS WILL CONTINUE TO MOVE ONSHORE ACROSS WESTERN
PANAMA...COSTA RICA AND NICARAGUA THROUGH THE EVENING HOURS WITH
THE HEAVIEST AND MOST CONCENTRATED ACTIVITY LOCATED OVER INLAND
NICARAGUA.

ATLANTIC OCEAN...
AN UPPER LEVEL SHORTWAVE TROUGH IS LOCATED WITHIN 120-150 NM E
OF THE OUTER BANKS OF NORTH CAROLINA SUPPORTING A SURFACE COLD
FRONT INTO THE SW NORTH ATLC WATERS FROM 32N72W SW TO ACROSS
GRAND BAHAMA ISLAND TO THE COAST OF FLORIDA JUST S OF WEST PALM
BEACH. MAINLY ZONAL FLOW IS ALOFT S OF 30N. THE FRONT CONTINUES
TO BECOME MORE DIFFUSE AS THE UPPER LEVEL ENERGY MOVES NE OF THE
AREA. EARLIER SHOWER ACTIVITY THAT WAS LOCATED N OF 28N E OF THE
FRONT HAS DIMINISHED AS THE FRONT CONTINUES TO WEAKEN. THE FRONT
IS FORECAST TO MOVE NE-E DURING THE NEXT 24-48 HOURS AS HIGH
PRESSURE BUILDS EASTWARD FROM THE NE GULF OF MEXICO. THE
REMAINDER OF THE SW NORTH ATLC IS UNDER A VERY WEAK AND BROAD
HIGH PRESSURE REGIME BETWEEN 57W AND SE OF THE AFOREMENTIONED
COLD FRONT. A FEW ISOLATED SHOWERS CONTINUE TO ADVECT WESTWARD
ACROSS THE TURKS AND CAICOS ISLANDS AND THE SE BAHAMAS THIS
EVENING. ACROSS THE CENTRAL ATLC...A COMPLEX SYSTEM INCLUDING
TWO SURFACE LOWS AND TROUGHS ARE MOVING NE-E. THE EASTERN AND
STRONGER LOW 1005 MB IS JUST N OF THE AREA NEAR 33N43W WITH A
TRAILING TROUGH ENTERING THE AREA NEAR 32N39W THROUGH 24N39W TO
17N50W. THE SECOND LOW 1010 MB IS POSITIONED NEAR 30N48W WITH A
TROUGH EXTENDING FROM THE LOW THROUGH 28N48W TO 27N54W. THE
MAJORITY OF THE ACTIVE WEATHER ASSOCIATED WITH THE STRONGER LOW
AND EASTERN TROUGH REMAINS N OF 32N. SCATTERED SHOWERS REMAIN
POSSIBLE WITHIN 120-150 NM EITHER SIDE OF THE EASTERN TROUGH AND
WITHIN 90-120 NM AHEAD OF THE WESTERN TROUGH. THE REMAINDER OF
THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE
ANCHORED BY A 1020 MB HIGH CENTERED NW OF THE CANARY ISLANDS
NEAR 32N24W. THE SURFACE RIDGE AXIS EXTENDS SW FROM THE HIGH
CENTER TO NEAR 16N37W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
LEWITSKY



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