[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120542
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE JUL 12 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0500 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IN THE WRN TRPCL ATLC EXTENDS FROM NEAR 15N54W TO
8N58W MOVING WNW NEAR 15 KT. WAVE CONTINUES TO PRECEDE A SURGE
OF DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER
IMAGERY. SATELLITE IMAGERY ALSO INDICATES LOW LEVEL CYCLONIC
FLOW IS AROUND THE WAVE AXIS CONFIRMED BY AN ASCAT SCATTEROMETER
PASS FROM 0038 UTC. SCATTERED MODERATE/STRONG CONVECTION IS FROM
11N-13N BETWEEN 54W-59W.

TROPICAL WAVE IN THE WRN CARIBBEAN EXTENDS JUST E OF NICARAGUA
FROM 18N83W TO 12N83W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN
A BROAD AREA OF ENHANCED MOISTURE ACROSS THE WRN CARIBBEAN. THE
WAVE LIES UNDER DIFFLUENT FLOW ALOFT WHICH IS HELPING ENHANCE
CONVECTION. IT IS DIFFICULT TO DETERMINE WHAT CONVECTION IS
CAUSED BY THE WAVE...THE UPPER LEVEL INFLUENCE...AND ALSO THE
MONSOON TROUGH TO THE S OF THE WAVE. NUMEROUS STRONG CONVECTION
IS FROM 8N-13N BETWEEN 82W-84W IMPACTING COSTA RICA. SIMILAR
ACTIVITY IS FROM 11N-15N BETWEEN 86W-90W IMPACTING HONDURAS.
SCATTERED MODERATE/STRONG CONVECTION IS ELSEWHERE S OF 19N
BETWEEN 80W-89W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA FROM THE PRIME MERIDIAN
AT 23N ALONG 22N11W 14N21W 8N34W. THE ITCZ CONTINUES FROM 8N34W
ALONG 6N45W 5N57W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS WITHIN 150 NM S OF THE AXIS BETWEEN 26W-34W.

...DISCUSSION...

GULF OF MEXICO...
LATE AFTERNOON SHOWER/THUNDERSTORM ACTIVITY HAS NOW DIED DOWN
ACROSS MUCH OF THE GULF OF MEXICO WHERE WEAK SURFACE RIDGING
PREVAILS CENTERED AROUND A 1018 MB HIGH OFF THE W CENTRAL COAST
OF FLORIDA NEAR 27N84W...AS 0F 0300 UTC. A WEAK SURFACE TROUGH
EXTENDS ACROSS THE FLORIDA PANHANDLE FROM 31N85W TO 29N87W
SUPPORTING A FEW REMNANT SHOWERS FROM 27N-29N BETWEEN 87W-89W. A
FEW ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SRN BAY OF
CAMPECHE S OF 20N BETWEEN 92W-95W. THE TROPICAL WAVE PREVIOUSLY
IN THE BAY OF CAMPECHE HAS NOW DISSIPATED OVER MEXICO. THE
REMAINDER OF THE BASIN IS UNDER FAIR WEATHER AND LIGHT WINDS.
ALOFT...AN UPPER LEVEL RIDGE COVERS THE NRN GULF N OF 25N
CENTERED OVER NRN ALABAMA. AN UPPER LEVEL TROUGH COVERS THE SW
GULF EXTENDING FROM SRN MEXICO NEAR 18N94W TO 26N89W. WATER
VAPOR IMAGERY INDICATES DRY AIR IS WRAPPING AROUND THE SRN
EXTENT OF THE UPPER RIDGE WHICH IS FURTHER SUPPORTING THE FAIR
WEATHER. TOTAL PRECIPITABLE WATER IMAGERY STILL INDICATES
ENHANCED MOISTURE IS ACROSS THE NRN GULF. WITH DAYTIME HEATING
THIS WILL LIKELY MEAN SHOWERS/THUNDERSTORMS WILL POP UP LATER IN
THE AFTERNOON TODAY. SHOWER/THUNDERSTORM ACTIVITY WILL ALSO
LIKELY INCREASE OVER THE SE GULF AS MOISTURE FROM A TROPICAL
WAVE IN THE WRN CARIBBEAN FLOWS INTO THE BASIN AS THE WAVE MOVES
WWD. WEAK SURFACE RIDGING WILL CONTINUE OVER THE NRN GULF.

CARIBBEAN SEA...
MOIST SWLY AND DIFFLUENT FLOW ALOFT COVERS THE NW CARIBBEAN
AROUND THE ERN SIDE OF INVERTED UPPER TROUGH OVER THE SRN GULF
OF MEXICO...AND A NARROW UPPER RIDGE EXTENDING FROM PANAMA TO
NEAR 17N83W. THIS AREA OF DIFFLUENCE LIES OVER A TROPICAL WAVE
ALONG 83W. THIS COMBINATION IS PRODUCING SHOWERS/THUNDERSTORMS
ACROSS THE WRN CARIBBEAN S OF 19N BETWEEN 80W-90W WITH THE
STRONGEST ACTIVITY ALONG THE WAVE AXIS....ACROSS COSTA
RICA...AND ACROSS WRN HONDURAS AND EL SALVADOR. SOME OF THE
ACTIVITY OVER COSTA RICA IS BEING INFLUENCED BY THE MONSOON
TROUGH EXTENDING FROM THE ERN PACIFIC ACROSS NRN COSTA RICA TO
NRN COLOMBIA WHERE THERE ARE ALSO SHOWERS/THUNDERSTORMS FROM
5N-11N BETWEEN 72W-80W. THE REMAINDER OF THE BASIN IS UNDER
MOSTLY FAIR CONDITIONS WITH 15-20 KT ELY TRADEWIND FLOW. A FEW
ISOLATED SHOWERS ARE NOTED IN THE NE CARIBBEAN N OF 15N E OF 70W
WITH A CLUSTER OF SHOWERS/THUNDERSTORMS OVER HAITI FROM 18N-19N
BETWEEN 71W-74W. THIS AREA IS ALSO IN AN AREA OF MODERATE
MOISTURE INDICATED BY TOTAL PRECIPITABLE WATER IMAGERY.
ALOFT...A HORIZONTALLY ALIGNED UPPER LEVEL TROUGH IS ACROSS THE
NRN CARIBBEAN WITH AXIS ALONG 18N. EXPECT SHOWER/THUNDERSTORM
ACTIVITY TO PERSIST ACROSS THE WRN CARIBBEAN AS MOISTURE
ASSOCIATED WITH THE TROPICAL WAVE REMAINS. ALSO...MUCH OF
CENTRAL AMERICA AND SRN MEXICO IS AT THREAT FOR PROLONGED HEAVY
RAINFALL THROUGHOUT THE END OF THE WEEK WHICH WILL INCREASE THE
CHANCE FOR DEADLY FLOODING AND MUDSLIDES. MODEL GUIDANCE
INDICATES THE MONSOON TROUGH WILL STRENGTHEN AND LIFT FARTHER N
PLACING ABNORMALLY STRONG WLY FLOW AGAINST CENTRAL AMERICA AND
SRN MEXICO. THIS W-SW FLOW WILL DRAW SIGNIFICANT TROPICAL
MOISTURE ACROSS THESE AREAS. COMBINED WITH OROGRAPHIC LIFT DUE
TO MOUNTAINS THIS CREATES A FORMULA TO EQUAL HEAVY
PRECIPITATION. THESE AREAS SHOULD MONITOR THE SITUATION OVER THE
NEXT FEW DAYS AND STAY TUNED FOR UPDATES ON THIS POSSIBLY
DANGEROUS SCENARIO.

ATLANTIC OCEAN...
SURFACE RIDGING DOMINATES THE MAJORITY OF THE ATLC TONIGHT
ANCHORED BY A 1029 MB HIGH NEAR 36N37W PROVIDING FAIR CONDITIONS
BASIN-WIDE. ALOFT AN UPPER LEVEL RIDGE COVERS THE WRN ATLC
CENTERED OVER NRN ALABAMA. AN UPPER LEVEL TROUGH IS TO THE E
ALONG 53W. A SHORTWAVE UPPER TROUGH EXTENDS OFF THE MAIN TROUGH
EXTENDING TO THE NW BAHAMAS ALONG 26N. THIS IS PRODUCING SOME
UPPER LEVEL CLOUDS FROM 21N-26N. A FEW ISOLATED SHOWERS ARE ALSO
FROM 26N-31N BETWEEN 51W-60W. UPPER LEVEL RIDGING COVERS MUCH OF
THE ERN ATLC CENTERED NEAR 35N33W. AN UPPER LEVEL TROUGH COVERS
THE FAR ERN ATLC EXTENDING ACROSS SPAIN TO THE CANARY ISLANDS.
ACROSS THE TROPICAL ATLC S OF 25N...AN UPPER LEVEL RIDGE IS
CENTERED OVER THE SRN WINDWARD ISLANDS NEAR 13N61W. AN UPPER
LEVEL LOW IS CENTERED NEAR 23N34W...AND AN UPPER LEVEL RIDGE IS
CENTERED OFF THE W COAST OF AFRICA NEAR 18N18W.

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

$$
WALTON





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