[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071748
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUL 07 2010

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC...

...SPECIAL FEATURE...

A BROAD AREA OF LOW PRESSURE IS
NW OF THE YUCATAN PENINSULA ANALYZED AS A SURFACE TROUGH
EXTENDING FROM 28N95W NEAR HOUSTON TEXAS TO A 1007 MB LOW CENTER
NEAR 23N93W TO 21N92W...AS OF 1500 UTC. SCATTERED
MODERATE/STRONG CONVECTION IS NEAR THE LOW CENTER FROM 21N-24N
BETWEEN 89W-94W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS ALSO S OF LOUISIANA/TEXAS FROM 26N-31N BETWEEN 90W-96W...AND
FROM 24N-27N BETWEEN 93W-94W. SCATTERED SHOWERS/THUNDERSTORMS
ARE ALSO ALONG THE SRN TEXAS COASTLINE. THE SHOWER/THUNDERSTORM
ACTIVITY HAS BECOME A LITTLE MORE ORGANIZED NEAR THE LOW CENTER.
ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE AND A TROPICAL
DEPRESSION COULD FORM BEFORE THE SYSTEM REACHES NE MEXICO OR SE
TEXAS AS IT MOVES WNW AT 10-15 KT.

...TROPICAL WAVES...

TROPICAL WAVE IS APPROACHING THE W AFRICA COAST ALONG 15W/16W S
OF 17N. A NORTHERN LOW-LEVEL DRY VORTICITY CENTER IS NEAR THE
NRN EXTEND OF THE WAVE AXIS ANALYZED AS A 1006 MB LOW NEAR
17N15W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
5N-9N BETWEEN 12W-19W.

TROPICAL WAVE IS ALONG 41W/42W S OF 18N MOVING W 15-20 KT. BROAD
CYCLONIC FLOW IS ABOUT THE WAVE AXIS EVIDENT IN VISIBLE
SATELLITE IMAGERY. THE WAVE ALSO LIES AHEAD OF A DEEP LAYER
MOISTURE MAXIMUM INDICATED BY TOTAL PRECIPITABLE WATER IMAGERY.
ISOLATED MODERATE/STRONG CONVECTION IS W OF THE AXIS FROM 9N-14N
BETWEEN 42W-48W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS ALSO S OF THE AXIS FROM 1S-5N BETWEEN 34W-44W. IT IS
UNCERTAIN WHETHER THE ACTIVITY S OF THE AXIS IS SOLELY
INFLUENCED BY THE TROPICAL WAVE.

TROPICAL WAVE EXTENDS FROM 12N54W TO 6N60W MOVING W 10-15 KT.
CYCLONIC FLOW IS ABOUT THE WAVE AXIS INDICATED BY VISIBLE
SATELLITE IMAGERY AND WINDSAT SCATTEROMETER DATA. WAVE LIES
AHEAD OF A SLIGHT BULGE IN DEEP LAYER MOISTURE EVIDENT IN TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 9N-12N BETWEEN 54W-57W...AND FROM 9N-12N
BETWEEN 59W-63W.

TROPICAL WAVE EXTENDS FROM S OF ERN CUBA NEAR 20N75W TO NRN
COLOMBIA NEAR 10N72W MOVING W NEAR 15 KT. WAVE IS AHEAD OF A
DEEP LAYER MOISTURE MAXIMUM EVIDENT IN TOTAL PRECIPITABLE WATER
IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS INLAND
OVER COLOMBIA FROM 7N-10N BETWEEN 74W-76W. ISOLATED
MODERATE/STRONG CONVECTION IS FROM 16W-21W BETWEEN 73W-77W.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N13W 4N27W 9N42W 10N56W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 2N-5N BETWEEN
24W-29W.

...DISCUSSION...

GULF OF MEXICO...
SIGNIFICANT DEEP LAYER MOISTURE CONTINUES TO IMPACT THE CENTRAL
AND NW GULF OF MEXICO TODAY DUE TO A BROAD AREA OF LOW PRESSURE
NW OF THE YUCATAN PENINSULA ANALYZED AS A SURFACE TROUGH
EXTENDING FROM 28N95W NEAR HOUSTON TEXAS TO A 1007 MB LOW CENTER
NEAR 23N93W TO 21N92W...AS OF 1500 UTC. SCATTERED
MODERATE/STRONG CONVECTION IS NEAR THE LOW CENTER FROM 21N-24N
BETWEEN 89W-94W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS ALSO S OF LOUISIANA/TEXAS FROM 26N-31N BETWEEN 90W-96W...AND
FROM 24N-27N BETWEEN 93W-94W. SCATTERED SHOWERS/THUNDERSTORMS
ARE ALSO ALONG THE SRN TEXAS COASTLINE. THE STRONG PRESSURE
GRADIENT BETWEEN THE LOW PRESSURE IN THE GULF AND HIGH PRESSURE
ACROSS THE ERN UNITED STATES IS SUPPORTING SE-S WINDS OF 20-30
KT E OF THE TROUGH AXIS TO 86W. SEE SPECIAL FEATURES ABOVE FOR
MORE DETAILS ON THIS SYSTEM. ALOFT...AN UPPER LEVEL LOW IS
CENTERED S OF BROWNSVILLE TEXAS NEAR 25N97W SUPPORTING THE BROAD
SURFACE LOW PRESSURE TO THE SE. THE UPPER LOW IS ACCOMPANIED BY
DRY AIR ALOFT KEEPING THE REMAINDER OF THE SW CARIBBEAN UNDER
GENERALLY FAIR CONDITIONS. WEAK UPPER LEVEL RIDGING COVERS THE
CENTRAL GULF WITH A NARROW UPPER LEVEL TROUGH COVERING THE ERN
GULF EXTENDING FROM AN UPPER LEVEL LOW IN THE W ATLC WITH AXIS
EXTENDING ACROSS THE BAHAMAS OVER THE SE GULF TO THE NE FLORIDA
PANHANDLE. WATER VAPOR IMAGERY INDICATES DRY AIR INTRUDING OVER
THE NE GULF BEHIND THIS UPPER TROUGH KEEPING SURFACE CONDITIONS
FAIR. EXPECT SHOWER/THUNDERSTORM ACTIVITY TO CONTINUE ACROSS THE
WRN GULF DUE TO THE AREA OF LOW PRESSURE WHICH IS FORECAST TO
MOVE WNW TOWARDS SE TEXAS/NE MEXICO OVER THE NEXT DAY OR SO.

CARIBBEAN SEA...
POSSIBLE ISOLATED SHOWERS ARE ACROSS THE NW CARIBBEAN AND CUBA
THIS AFTERNOON DUE TO MOISTURE LEFT BEHIND BY THE AREA OF LOW
PRESSURE NOW NW OF THE YUCATAN PENINSULA. A FEW ISOLATED
SHOWERS/THUNDERSTORMS ARE ALSO ACROSS THE SW CARIBBEAN DUE TO
SURFACE CONVERGENCE NEAR A PORTION OF THE ITCZ THAT EXTENDS
ACROSS COSTA RICA TO THE NRN COLOMBIA COAST ALONG 10N84W 11N80W
9N75W. THE REMAINDER OF THE WRN CARIBBEAN IS EXPERIENCING
GENERALLY FAIR WEATHER DUE TO AN AREA OF DRY AIR ALOFT AROUND A
WEAK UPPER LEVEL TROUGH OVER THE S CENTRAL CARIBBEAN. A TROPICAL
WAVE EXTENDING FROM ERN CUBA TO THE NRN COLOMBIA COAST IS
ENHANCING SCATTERED SHOWERS/THUNDERSTORMS ACROSS ERN CUBA AND
THE WATERS TO THE S FROM 16W-21W BETWEEN 73W-77W. ISOLATED
SHOWERS/THUNDERSTORMS ARE ALSO E OF THE WAVE S OF HISPANIOLA
FROM 14N-17N BETWEEN 68W-76W. THE REMAINDER OF THE BASIN IS
UNDER MAINLY CLEAR SKIES AND FAIR WEATHER UNDER THE INFLUENCE OF
AN UPPER LEVEL RIDGE COVERING THE ERN CARIBBEAN CENTERED NEAR
13N63W. DRY AIR IS ALSO FILTERING IN FROM THE ATLC. EXPECT
SHOWER ACTIVITY TO REMAIN NEAR THE TROPICAL WAVE AS IT
PROGRESSES WWD. SHOWERS/THUNDERSTORMS WILL START IMPACTING THE
WINDWARD ISLANDS AND ERN CARIBBEAN AS A TROPICAL WAVE E OF THE
BASIN APPROACHES THE AREA OVER THE NEXT 24 HRS.

ATLANTIC OCEAN...
AN UPPER LEVEL LOW SPINNING N OF THE DISCUSSION AREA NEAR 33N68W
WITH AXIS CONTINUING ACROSS THE BAHAMAS TO THE STRAITS OF
FLORIDA AND INTO THE SE GULF IS SUPPORTING SEVERAL WAVES OF
ENERGY ACROSS THE W ATLC ANALYZED AS A PAIR OF SURFACE TROUGHS.
THE FIRST IS ANALYZED FROM 30N65W TO 27N75W. THE SECOND IS ALONG
27N64W 24N71W. THE COMBINATION OF THESE FEATURES IS ENHANCING
NUMEROUS STRONG CONVECTION FROM 22N-26N BETWEEN 68W-71W.
SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO FROM 22N-27N BETWEEN
64W-68W...AND FROM 26N-33N BETWEEN 59W-65W. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO ACROSS THE NW BAHAMAS FROM
23N-26N BETWEEN 76W-80W SUPPORTED BY THE NARROW EXTENSION OF THE
UPPER LEVEL TROUGH TOWARDS THE SE GULF. POSSIBLE ISOLATED
SHOWERS ARE ACROSS THE REMAINDER OF THE W ATLC. FARTHER E...A
BROAD SURFACE RIDGE DOMINATES ANCHORED BY A PAIR OF 1029 AND
1028 MB HIGHS LOCATED NEAR 40N30W AND 37NM45W RESPECTIVELY
KEEPING CONDITIONS FAIR ACROSS THE ERN ATLC. HOWEVER...A SURFACE
TROUGH EXTENDS FROM 31N46W TO 22N46W. POSSIBLE ISOLATED SHOWERS
ARE ALONG THE TROUGH AXIS. ALOFT...AN UPPER LEVEL TROUGH IS
BETWEEN 42W-58W CENTERED NEAR 25N48W...WITH AN UPPER LEVEL RIDGE
TO THE E BETWEEN 22W-42W CENTERED NEAR 19N34W. AN UPPER LEVEL
TROUGH EXTENDING FROM THE PORTUGAL COAST COVERS THE FAR ERN ATLC
E OF THE CAPE VERDE ISLANDS.

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

$$
WALTON





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