[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 021731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU AUG 02 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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 1715 UTC.

...SPECIAL FEATURES...
A TROPICAL WAVE AND AN AREA OF LOW PRES IN THE E CARIB IS MOVING
WWD NEAR 20 KT. A SATELLITE LOOP BEGINNING AT 00Z TODAY SHOWS
CONVECTION SIGNIFICANTLY INCREASING IN BOTH COVERAGE AND
MAGNITUDE...ALTHOUGH CLOUD TOPS HAVE WARMED A BIT OVER THE PAST
HOUR OR TWO. CURRENTLY...SCATTERED TO NUMEROUS MODERATE
CONVECTION IS FROM 13N-17N BETWEEN 64W-70W. WHILE CONVECTION IS
IMPRESSIVE IT REMAINS CHALLENGING TO FIND THE LOW-LEVEL CENTER.
THIS SYSTEM CONTINUES TO HAVE SOME POTENTIAL TO BECOME A
TROPICAL CYCLONE DURING THE NEXT DAY OR SO. AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT IS CURRENTLY ENROUTE TO INVESTIGATE
THE SYSTEM.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 29W/30W S OF 18N MOVING W 15-20 KT.
BESIDES FOR A FEW LOW TO MID CLOUD SWIRLS AND SCATTERED SHOWERS
ALONG THE WAVE AXIS...THERE IS NOT MUCH ASSOCIATED ACTIVITY.
STABLE DUSTY AIR SURROUNDS THE NRN EXTENSION OF THE WAVE AXIS.

HIGH AMPLITUDE TROPICAL WAVE IS ALONG 44W MOVING W NEAR 15 KT
OVER THE PAST 24 HOURS. THIS WAVE HAS A LARGE ENVELOPE OF LOW TO
MID LEVEL CYCLONIC TURNING CLEARLY NOTED IN VISIBLE IMAGES WITH
A WEAK LOW LEVEL CIRCULATION...ANALYZED 1012 MB...ALONG THE AXIS
NEAR 11N. ALTHOUGH THE OVERALL STRUCTURE AND SIZE OF THIS WAVE
IS RATHER IMPRESSIVE...CONVECTION IS CONFINED TO THE ITCZ WITH
LITTLE SHOWER ACTIVITY NEAR THE WAVE AXIS ITSELF.

TROPICAL WAVE IS ALONG 75W S OF 20N MOVING W NEAR 20 KT. THE
WAVE PSN WAS ADJUSTED SLIGHTLY ON THIS MAP TO AGREE WITH A WWD
MOVING SURGE OF MOISTURE EVIDENT ON THE UW-CIMSS TPW PRODUCT.
REGARDLESS OF THE EXACT PSN...THERE IS NOT MUCH CURVATURE OR
ORGANIZING TO THIS LOW-LEVEL FEATURE. A WEAKENING SMALL CLUSTER
OF SHOWERS OVER ERN CUBA AND THE MORE TYPICAL FLARE UPS ALONG
THE ITCZ AXIS IN THE SW CARIB ARE POSSIBLY ENHANCED BY THIS
WAVE.

TROPICAL WAVE IS ALONG 87W S OF 20N MOVING W NEAR 20 KT. LIKE
THE WAVE TO ITS E...THE PSN WAS UPDATED ON THIS MAP IN RESPONSE
TO A WEAK SURGE OF MOISTURE EVIDENT IN THE TPW FIELD. OTHERWISE
CONVECTION NEAR IT IS MINIMAL ACROSS CENTRAL AMERICA AND THE
CARIB WATERS. THERE IS A BURST IN THE EPAC WATERS...FOR MORE
DETAILS REFER TO MIATWDEP.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N17W 11N32W 8N46W 10N55W 11N63W.
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM S OF THE AXIS
BETWEEN 42W-50W AND WITHIN 90 NM EITHER SIDE BETWEEN 50W-54W.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 120 NM S OF THE
AXIS E OF 30W.

...DISCUSSION...
THE GULF OF MEXICO...
MESSY WEATHER CONTINUES IN THE GULF OF MEXICO ASSOCIATED WITH A
BROAD ELONGATED LOW PRES TROUGH. AS OF 15 UTC...THE BOUNDARY WAS
ANALYZED FROM THE BIG BEND AREA OF FLORIDA TOWARD THE SE TEXAS
COAST ALONG 29N83W 27N89W 29N96W. VISIBLE IMAGES AND SFC OBS
SHOW BROAD ELONGATED CYCLONIC TURNING ALONG THIS TROUGH AXIS
WITH SOME CONCENTRATION AND LOWER PRESSURES NEAR 28N86W...WHERE
A 1011 MB LOW IS ANALYZED. IR IMAGES...LIGHTNING DATA AND
AVAILABLE RADAR DATA INDICATE THAT SCATTERED SHOWERS AND TSTMS
COVER THE REGION FROM 26N-30N...MOST ORGANIZED IN THE E GULF AND
OVER CENTRAL FLORIDA. WHILE THIS LOW PRES SYSTEM IS POORLY
ORGANIZED AT THE MOMENT...IT IS RESPONSIBLE FOR QUITE WINDY
CONDITIONS...ESPECIALLY IN TSTMS...AS INDICATED BY SEVERAL SHIPS
REPORTS IN THE 20-25 KT RANGE. THIS SHOWER ACTIVITY IS BEING
ENHANCED BY A DIFFLUENT PATTERN ALOFT BETWEEN A SHORTWAVE TROUGH
OVER THE SE STATES AND AN UPPER HIGH OVER THE SW U.S. THIS
SYSTEM WILL CONTINUE TO BE MONITORED AS SLOW DEVELOPMENT IS
POSSIBLE OVER THE NEXT DAY OR TWO. DEBRIS HIGH LEVEL CLOUDINESS
COVERS MUCH OF THE REMAINDER OF THE GULF...EXCEPT FOR THE
EXTREME SE PORTION AND S FLA...WHERE DRY AIR FROM THE BAHAMAS IS
BEING ADVECTED IN.

THE CARIBBEAN SEA...
THE BIG STORY IN THE CARIB IS ASSOCIATED WITH THE SPECIAL
FEATURE...SEE ABOVE. TWO OTHER TROPICAL WAVES ARE MOVING ACROSS
THIS REGION GENERALLY HAVING LITTLE EFFECT ON THE WEATHER
CONDITIONS ATTM. AN UPPER LOW IS SPINNING OVER THE SW CARIB NEAR
14N80W ENHANCING DRY STABLE AIR IN THE MID AND UPPER LEVELS
FROM 13N-18N W OF 75W. PATCHES OF CLOUDS AND ISOLATED SHOWERS
ARE ROTATING AROUND THE NRN SIDE OF THIS UPPER SYSTEM N OF 18N W
OF 75W. CLUSTER OF SCATTERED MODERATE CONVECTION IS OVER THE SW
PORTION S OF 11N W OF 78W TIED TO THE ITCZ. MAX TRADES ARE NEAR
25 KT NEAR THE COAST OF COLOMBIA...AS DEPICTED BY A QSCAT PASS
NEAR 11Z.

THE ATLANTIC OCEAN...
WEAKENING SLOW MOVING FRONTAL BOUNDARY EXTENDS FROM NEAR BERMUDA
TO NE FLORIDA. THIS BOUNDARY CONTINUES IN THE GULF...WHERE IT
LACKS THERMAL GRADIENT. IR IMAGES AND LIGHTNING DATA INDICATE
THAT SCATTERED SHOWERS AND TSTMS ARE WITHIN 60 NM OF THE FRONT.
THE REMAINDER OF THE ATLC IS DOMINATED BY A 1029 MB HIGH NEAR
37N33W. THE COMBINATION OF THIS HIGH PRES AND A LARGE AREA OF
STABLE AIR ALOFT IS PRODUCING WIDESPREAD FAIR WEATHER ACROSS THE
MAJORITY OF THE ATLC BASIN TODAY. THE ONLY AREA OF CLOUDINESS
WORTH NOTING...BESIDES THE TROPICAL WAVES DISCUSSED
ABOVE...EXTENDS FROM 25N-30N BETWEEN 55W-59W. THIS MOISTURE IS
ASSOCIATED WITH A LARGE UPPER LOW CENTERED NEAR 30N55W.
OTHERWISE...THE TYPICAL STABLE SCATTERED LOW-LEVEL STRATOCUMULUS
ARE THE MAIN SOURCE OF CLOUD COVER ACROSS THIS REGION. TRADES
ARE MODERATE...EXCEPT NEAR THE ERN CARIB AND THE COAST OF AFRICA
WHERE THE TIGHTENED PRES GRAD IS PRODUCING STRONGER WINDS.

$$
CANGIALOSI




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