[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 302340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT APR 30 2016

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/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS INTO THE EASTERN TROPICAL ATLC NEAR
09N13W...AND CONTINUES TO 05N18W...WHERE SCATTEROMETER AND MODEL
GUIDANCE SUGGEST THAT THE ITCZ AXIS BEGINS AND CONTINUES TO
03N30W TO 04N40W TO INLAND S AMERICA AT 04N52W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM S OF THE
AXIS BETWEEN 20W-24W. SCATTERED MODERATE CONVECTION IS WITHIN
180 NM N OF THE AXIS BETWEEN 49W-54W.

...DISCUSSION...

GULF OF MEXICO...

THE WESTERN EXTENSION OF RATHER ATLC HIGH PRES EXTENDS WESTWARD TO OVER
THE EASTERN PORTION OF THE GULF. BROAD LOW PRES IS ELSEWHERE ACROSS
THE GULF WITH AN ASSOCIATED 1002 MB LOW CENTERED IN THE SW GULF JUST
NE OF TAMPICO NEAR 22N97W WITH A TROUGH EXTENDING NNE TO 26N96W TO 28N94W
TO SW LOUISIANA WHERE AN OUTFLOW BOUNDARY THEN EXTENDS N TO OVER
SW LOUISIANA. AN UPPER TROUGH OVER EASTERN TEXAS IS SUPPORTING THE
SURFACE TROUGH THAT EXTENDS FROM THE 1002 MB LOW. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS NOTED ON BOTH NWS MOSAIC RADAR ON SATELLITE
IMAGERY MOVING EASTWARD ALONG AND JUST OFFSHORE THE COASTS OF
LOUISIANA...SPREADING EASTWARD TO THE FAR WESTERN FLORIDA
PANHANDLE. THIS ACTIVITY IS BEING FURTHER SUPPORTED BY AN UPPER
SHORTWAVE TROUGH SWINGING EASTWARD ACROSS EASTERN LOUISIANA AND
WESTERN MISSISSIPPI. SIMILAR CONVECTION IS OVER THE WESTERN BAY
OF CAMPECHE WITHIN 30 NM OF A LINE FROM THE VERACRUZ AREA E TO
NEAR 20N94W. THIS ACTIVITY IS BEING AIDED BY AN UPPER LEVEL
DISTURBANCE RIDING EASTWARD ACROSS THE CREST OF UPPER LEVEL
RIDGING LOCATED OVER THE WESTERN PART OF THE GULF S OF 25N. THE
AFOREMENTIONED CONVECTION FROM SE LOUISIANA TO THE WESTERN
FLORIDA PANHANDLE WILL CONTINUE TO SHIFT EASTWARD INTO EARLY
SUN. THE CONVECTION IN THE SW GULF WILL ALSO CONTINUE TO
TRANSLATE EASTWARD THROUGH SUN. THE PRES GRADIENT BETWEEN THE
HIGH PRES OVER THE EASTERN GULF AND LOWER PRES OVER THE WESTERN
GULF IS ENOUGH TO SUPPORT MODERATE SE WINDS OVER THE EASTERN
GULF...AND FRESH TO LOCALLY STRONG SE WINDS OVER THE MAJORITY OF
THE CENTRAL AND WESTERN GULF. A WEAK COLD FRONT IS FORECAST MOVE
ACROSS THE NW GULF LATE ON MON.

CARIBBEAN SEA...

A BROAD UPPER TROUGH OVER THE SW N ATLC CONTINUES TO INTERACT
WITH A MOIST AND UNSTABLE AIRMASS PRESENT OVER THE BASIN SETTING
OFF CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION N
OF 15N BETWEEN 62W-71W...INCLUDING MOST OF PUERTO RICO AND THE
VIRGIN ISLANDS. THIS UNSETTLED WEATHER PATTERN IS FORECAST TO
REMAIN IN PLACE THROUGH THE NEXT 24-48 HOURS AS THE TROUGH
SLOWLY MOVES EASTWARD...AND WHILE AT THE SAME UPPER SHORTWAVE
ENERGY PASS OVER THE EASTERN CARIBBEAN SEA. SCATTERED MODERATE
CONVECTION OVER MUCH OF COSTA RICA AND PANAMA DEVELOPED WITH
DAYTIME HEATING...AND WITH THE ADDED INGREDIENT OF THE WELL
PRONOUNCED SEABREEZE FRONT NOTED IN THE 18 UTC SURFACE ANALYSIS.
THIS ACTIVITY IS EXPECTED TO DIMINISH TONIGHT...THEN REDEVELOP
ON SUN. ISOLATED SHOWERS AND TSTMS ARE SEEN N OF 15N W OF 71W.
BOTH BUOY AND EARLIER SCATTEROMETER DATA SHOW MODERATE TRADE
WIND FLOW THROUGHOUT...EXCEPT FOR MODERATE TO FRESH TRADES N OF
HONDURAS TO 18N. THESE WINDS ARE FORECAST TO CONTINUE INTO MON.

HISPANIOLA...

AN UPPER LOW EMBEDDED WITHIN THE UPPER TROUGH DESCRIBED ABOVE
UNDER CARIBBEAN SECTION IS CENTERED ROUGHLY ABOUT 150 NM NE
OF HISPANIOLA. THE TAIL END OF THE UPPER TROUGH EXTENDS SW
ACROSS HISPANIOLA TO NEAR 15N72W. THIS FEATURE IS ADDING PLENTY
OF FUEL TO AN ALREADY VERY MOIST AND UNSTABLE AIR MASS IN PLACE
OVER AND NEAR THE ISLAND. UPPER DIVERGENCE TO THE SE OF THE
UPPER LOW IS SIGNIFICANTLY AIDING THE SCATTERED MODERATE
CONVECTIVE ACTIVITY THAT EARLIER TODAY FIRED UP OVER MUCH OF THE
DOMINICAN REPUBLIC AS OBSERVED ON SATELLITE IMAGERY...AND AS
BEING REPORTED BY THE LATEST SURFACE BASED WEATHER REPORTING
SITES THROUGHOUT THE ISLAND. THIS ACTIVITY IS BEING ACCOMPANIED
BY FREQUENT LIGHTNING AT TIMES. AS MENTIONED ABOVE UNDER
CARIBBEAN SEA...THE UPPER TROUGH IS ONLY EXPECTED TO SLOWLY MOVE
EASTWARD THROUGH MON. THERE IS A GOOD POSSIBILITY THAT THIS
CONVECTIVE ACTIVITY WILL BE ACTIVE AGAIN ON SUN...BUT PERHAPS A
LITTLE LESS ACTIVE ON MON AS THE TROUGH AXIS PULLS JUTS TO THE E
OF THE ISLAND.

ATLANTIC OCEAN...

AN UPPER TROUGH ENTERS THE AREA THROUGH 32N56W...AND CONTINUES
SW TO 26N63W...TO AN UPPER LOW AT 22N69W...AND SW TO ACROSS
HISPANIOLA AND TO THE N CENTRAL CARIBBEAN SEA. AT THE SURFACE...
THIS FEATURE IS SEEN AS A TROUGH FROM 32N56W SW TO A WEAK 1015
MB LOW AT 26N60W...AND SW FROM THERE TO NEAR 22N65W. VERY DEEP
MOISTURE...IN THE FORM OF OVERCAST MULTILAYER CLOUDS...ARE NOTED
TO THE SE OF THE TROUGH AND LOW W OF ABOUT 52W. SCATTERED
MODERATE CONVECTION IS OCCURRING FROM 17N-23N BETWEEN 60W-64W.
ASSOCIATED HIGH LEVEL DEBRIS BROKEN TO OVERCAST CIRRUS CLOUDS
ARE STREAMING EASTWARD FROM THIS ACTIVITY TO NEAR 50W...THEN
THINS OUT TO MOSTLY BROKEN CLOUDS TO NEAR 39W. A WEAK BACKDOOR
COLD FRONT IS ALONG 30N BETWEEN 70W-78W. NO CONVECTION IS
OCCURRING WITH THIS FRONT. THE UPPER TROUGH AND LOW WILL SLOWLY
MOVE EASTWARD OVER THE NEXT 48 HOURS. THE WEAK 1015 MB LOW AT
26N60W IS FORECAST TO MOVE NE TO NEAR 27N58W BY SUN
AFTERNOON...THEN GRADUALLY DISSIPATE ALONG THE TROUGH ON MON. A
SURFACE TROUGH...THAT DURING THE PAST FEW DAYS HAS BEEN STEADILY
MOVING WESTWARD...WAS ANALYZED AT 18 UTC FROM JUST NW OF HAITI
NNE TO NEAR 27N71W. THIS TROUGH IS ON THE BACK SIDE OF THE UPPER
LEVEL LOW AND UPPER TROUGH...WHICH PUTS IT UNDER A REGION OF
MODERATE SUBSIDENCE AND DRY SINKING AIR. SO ONLY ISOLATED
SHOWERS AND WEAK ISOLATED TSTMS ARE NOTED WITHIN 90 NM OF THE
TROUGH. THE TROUGH IS FORECAST TO WASH OUT ON SUN. THE COLD
FRONT IS FORECAST TO CLIP FAR NORTHERN WATERS BETWEEN 60W-70W
EARLY ON SUN...AND DISSIPATE BY LATE SUN.

OVER THE FAR EASTERN PART OF THE AREA A 1013 MB LOW IS CENTERED
AT 26N37W WITH A TROUGH EXTENDING SSW FROM THE LOW TO NEAR
21N40W. THIS LOW REMAINS EMBEDDED UNDERNEATH A BROAD UPPER LOW
WHICH IS SUPPORTING WIDELY SCATTERED SHOWERS AND TSTMS FROM  24N
TO 28N BETWEEN 26W-33W. THE LOW IS FORECAST TO MOVE SW TO NEAR
25N40W BY SUN AFTERNOON...AND REMAIN NEARLY STATIONARY THROUGH
EARLY MON BEFORE OPENING UP TO A TROUGH LATER ON MON AS THE
UPPER BROAD LOW PULLS OFF FAR TO THE EASTERN ATLC NEAR THE COAST
OF AFRICA. WEAK SURFACE RIDGING WILL REMAIN IN PLACE OVER THE
EASTERN ATLC THROUGH MON.

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

$$
AGUIRRE
This weather bulletin was brought to you by:
www.nashvilleweather.net