[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261200
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED JUL 26 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURE...

A 1009 MB SURFACE LOW PRESSURE CENTER IS INLAND OVER SOUTH TEXAS
NEAR 28.5N 97.7W MOVING NORTHWARD ABOUT 10 KT.  THIS SYSTEM IS
GENERATING A LARGE AREA OF SHOWERS...THUNDERSTORMS AND GUSTY
WINDS IN SQUALLS OVER PARTS OF THE WESTERN GULF OF MEXICO AND
THE ADJACENT COASTAL AREAS.  SCATTERED MODERATE CONVECTION
EXISTS FROM 25N-30N BETWEEN 92W-98W. A FEW BUOYS IN THE NW GULF
INDICATE WINDS NEAR 20-25 KT...ESPECIALLY IN CONVECTION. SINCE
THE SURFACE LOW CENTER IS OVER LAND AND NOT EXPECTED TO REFORM
OR EMERGE OFFSHORE...DEVELOPMENT IS NOT EXPECTED.  LOCALLY HEAVY
RAINFALL WILL CONTINUE TO OCCUR OVER PORTIONS OF SOUTHERN TEXAS
AND SOUTHERN LOUISIANA TODAY.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 28W/29W S OF 21N MOVING WEST 15-20 KT.
THIS WAVE HAS SOME LOW-MID LEVEL CURVATURE ESPECIALLY SOUTH OF
14N EVIDENT ON EARLY MORNING VISIBLE IMAGES. THE WAVE IS AN AREA
OF THICK SAHARAN DUST THAT IS SUPPRESSING SIGNIFICANT
CONVECTION. ISOLATED MODERATE CONVECTION IS EMBEDDED IN THE ITCZ
AND WILL BE DISCUSSED IN THAT SECTION.

A HIGH AMPLITUDE TROPICAL WAVE IS ALONG 57W S OF 25N MOVING WEST
NEAR 15-20 KT. THE AREA OF LOW PRES THAT HAS BEEN ALONG THE WAVE
OVER THE PAST FEW DAYS IS NO LONGER EVIDENT IN SATELLITE IMAGERY
AND THE AVAILABLE DATA. HOWEVER...THE WAVE STILL REMAINS
WELL-DEFINED WITH A TITLED INVERTED V-SHAPE EVIDENT. SHOWER
ACTIVITY HAS ALSO INCREASED SLIGHTLY WITH SCATTERED SHOWERS AND
ISOLATED TSTMS WITHIN 180 NM OF THE WAVE AXIS. FURTHER
DEVELOPMENT IS NOT EXPECTED AT THIS TIME DUE TO UNFAVORABLE
UPPER LEVEL WINDS.

TROPICAL WAVE IS ALONG 77W S OF 18N MOVING WEST NEAR 15 KT. THIS
WAVE REMAINS WEAK AND DIFFICULT TO IDENTITY. THE POSITION IS
BASED UPON CONTINUITY OF FORWARD SPEED OVER THE PAST 12-24
HOURS. THE SOUTHERN PART OF THE WAVE INTERACTING WITH THE ITCZ
IS TRIGGERING NUMEROUS MODERATE/STRONG CONVECTION OVER WRN
COLOMBIA. THE NORTHERN EXTENSION OF THE WAVE IS INTERACTING WITH
AN UPPER LOW NEAR CENTRAL CUBA PRODUCING SCATTERED SHOWERS AND
TSTMS FROM HAITI TO THE YUCATAN CHANNEL.

TROPICAL WAVE IS ALONG 89W S OF 17N MOVING WEST NEAR 15 KT.
THIS WAVE SHOWS FAIR CURVATURE SOUTH OF 12N. SCATTERED MODERATE
CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS.

...ITCZ...
ITCZ IS CENTERED ALONG 11N14W 12N30W 8N45W TO INLAND OVER SOUTH
AMERICA NEAR 11N61W TO PANAMA NEAR 9N80W. SMALL PATCHES OF
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM MAINLY TO THE
SOUTH OF THE AXIS E OF 52W. CLUSTERS OF SCATTERED MODERATE
CONVECTION IS OVER E VENEZUELA FROM 4N-8N BETWEEN 60W-64W.
NUMEROUS MODERATE/STRONG CONVECTION IS OVER WRN COLOMBIA FROM
3N-10N BETWEEN 74W-80W.

...DISCUSSION...
GULF OF MEXICO...
THE MOST ACTIVE WEATHER IN THE REGION IS IN THE WEST GULF
ASSOCIATED WITH A 1009 MB LOW JUST INLAND OVER SOUTH TEXAS. LOW
LEVEL CONVERGENCE AND UPPER DIFFLUENCE IS PRODUCING SCATTERED
MODERATE CONVECTION FROM 25N-30N BETWEEN 92W-98W. FOR MORE
DETAILS SEE THE SPECIAL FEATURE SECTION ABOVE. AN ELONGATED
UPPER LEVEL HIGH IS CENTERED IN THE EASTERN GULF NEAR 27N87W.
DEBRIS MOISTURE IS STREAMING ANTICYCLONICALLY AROUND THE UPPER
HIGH FROM THE CONVECTION IN THE W GULF ACROSS THE SE U.S. AND
THEN SOUTHWARD ACROSS THE W ATLC AND FLORIDA. EARLIER THIS
MORNING...PATCHES OF SCATTERED SHOWERS AND TSTMS DEVELOPED IN
THE SE GULF ON THE SOUTHWARD BRANCH OF THE ANTICYCLONE.
CURRENTLY MUCH OF THE ACTIVITY HAS MOVED SOUTHWARD INTO THE
CARIBBEAN AND BLOSSOMED AS UPPER DIFFLUENCE IS STRONGER IN THAT
REGION. AT THE SURFACE...HIGH PRES RIDGING HAS BUILT FROM THE
CENTRAL ATLC ACROSS FLORIDA TO A 1019 MB HIGH IN THE E GULF NEAR
28N85W.  A WEDGE OF DRY UPPER LEVEL AIR IS IN THE CENTRAL GULF
BETWEEN 85W-90W KEEPING SKIES MAINLY FAIR. SURFACE WINDS ARE
FAIRLY LIGHT E OF 88W. W OF 88W...WINDS ARE STRONGER WITH A FEW
BUOYS REPORTING 20-25 KT IN THE NW GULF ESPECIALLY IN AREAS OF
CONVECTION. THE HEAVY RAIN IN THE NW GULF WILL SLOWLY DRIFT NWD
WITH THE SFC LOW THROUGHOUT THE DAY...ELSEWHERE LITTLE CHANGE IS
EXPECTED.

CARIBBEAN SEA...
TWO WEAK ILL-DEFINED TROPICAL WAVES ARE IN THE CARIBBEAN. THE
WESTERN-MOST WAVE IS RATHER BENIGN ONLY ENHANCING SHOWER
ACTIVITY IN THE ITCZ. UPPER DIFFLUENCE BETWEEN AN UPPER HIGH IN
THE E GULF AND AN UPPER LOW JUST SOUTH OF CENTRAL CUBA
INTERACTING WITH A TROPICAL WAVE ALONG 77W IS GENERATING PATCHES
OF SHOWERS AND TSTMS FROM HAITI TO THE YUCATAN CHANNEL FROM
18N-21N BETWEEN 74W-88W. THESE SHOWERS HAVE BECOME MUCH MORE
WIDESPREAD OVER THE LAST FEW HOURS. A WEAK UPPER RIDGE COVERS
THE AREA E OF 70W WITH PLENTY OF SUBSIDENCE. A WELL-DEFINED
TROPICAL WAVE IS APPROACHING THE AREA ALREADY ENHANCING
SCATTERED SHOWERS AND TSTMS ACROSS THE WINDWARD ISLANDS. THIS
WAVE WILL BE MOVING INTO THE LESSER ANTILLES LATER TODAY AND TO
PUERTO RICO AND HISPANIOLA ON THU INCREASING THE CHANCE OF RAIN
AS IT APPROACHES.  TRADE WINDS HAVE DECREASED FROM GALE FORCE
EARLIER THIS WEEK TO MORE MODERATE THIS MORNING AND THESE WINDS
WILL LIKELY REMAIN THAT WAY FOR THE NEXT DAY OR TWO.

ATLANTIC OCEAN...
THE MAIN SURFACE FEATURE IN THE ATLC IS A DOMINATING
BERMUDA-AZORES RIDGE WITH A PAIR OF 1027 MB HIGHS CENTERS...ONE
NEAR 37N53W AND THE OTHER NEAR 37N44W. THIS RIDGE IS
CONTAMINATED BY A WEAK BENIGN 1019 MB LOW JUST N OF THE
DISCUSSION AREA NEAR 34N28W. MODERATE E-ENE WINDS AND PATCHES OF
LOW-MID LEVEL MOISTURE ARE ON THE SOUTH SIDE OF THE ESTABLISHED
RIDGE. THE TIGHTEST PRES GRAD IS NEAR THE TROPICAL WAVE ALONG
57W. BESIDES FOR THE TROPICAL WAVES...THERE ARE ONLY A FEW AREAS
OF SOME WEATHER IN THE ATLC MAINLY CONTRIBUTED TO UPPER LEVEL
FEATURES. ISOLATED SHOWERS AND TSTMS ARE IN THE W ATLC...N OF
29N W OF 75W...MOVING AROUND THE PERIPHERY OF AN UPPER RIDGE IN
THE E GULF. THIS ACTIVITY HAS BEEN FALLING APART THIS MORNING.
TWO UPPER LOW'S ONE NEAR 29N64W AND THE OTHER NEAR 29N55W ARE
RATHER DRY FEATURES ONLY PRODUCING BROKEN CLOUDS AND ISOLATED
SHOWERS ON THE S AND E SIDE OF THEIR CIRCULATION.  THE REMAINDER
OF THE AREA IS ON THE SOUTH SIDE OF AN AMPLIFIED UPPER
RIDGE/TROUGH PATTERN WITH THE RIDGE AXIS ALONG 45W AND THE BASE
OF THE UPPER TROUGH DIGGING TO NEAR 30N19W. THE UW-CIMSS SAHARAN
AIR LAYER ANALYSIS FROM 09 UTC DEPICTS THAT THE LEADING EDGE OF
THICK DUST IS BEHIND THE WELL DEFINED TROPICAL WAVE APPROACHING
THE CARIBBEAN...E OF 57W FROM 10N-30N. SCATTERED LESS DENSE DUST
HAS SPREAD ACROSS THE ENTIRE CARIBBEAN.

$$
CANGIALOSI


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