[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131119
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SUN JAN 13 2008

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 9N13W 4N30W 1N140W CROSSING THE
EQUATOR NEAR 45W TO 1S47W. SCATTERED MODERATE ISOLATED STRONG
CONVECTION IS WITHIN 60 NM OF THE AXIS BETWEEN 23W AND 30W.
SCATTERED MODERATE TO STRONG CONVECTION IS FROM THE EQUATOR TO 3N
BETWEEN THE PRIME MERIDIAN AND 8W.

...DISCUSSION...

THE GULF OF MEXICO...
A STATIONARY FRONTAL BOUNDARY REMAINS STALLED FROM JUST NORTH OF
CEDAR KEY FLORIDA THROUGH TWO WEAK AREAS OF 1013 MB LOW PRESSURE
ALONG THE FRONT NEAR 28N86W AND 26N91W. THE FRONT THEN TRANSITIONS
TO A COLD FRONT TO THE EAST COAST OF MEXICO NEAR TAMPICO. DOPPLER
RADAR AND LIGHTNING DATA SUGGEST SCATTERED SHOWERS AND TSTMS ARE
WITHIN 60 NM N OF THE STATIONARY FRONT OVER THE NORTHEAST GULF. THE
FRONT IS BECOMING ENERGIZED AS UPPER LEVEL SUPPORT IS ARRIVING IN
THE FORM OF A LARGE UPPER TROUGH SWINGING ACROSS THE WESTERN
LOUISIANA/UPPER TEXAS COAST TOWARD THE NW GULF OF MEXICO. THIS
TROUGH IS SUPPORTING A COLD FRONT WHICH EXTENDS FROM NEAR CAMERON
LOUISIANA SOUTHWARD TO THE FAR NE MEXICAN COAST. THIS FRONT IS
WEAKENING AS ENERGY IS BEING TRANSFERRED TO THE STATIONARY FRONT
OVER THE EASTERN GULF AND EVENTUAL LOW PRESSURE DEVELOPMENT OFF THE
CAROLINA COAST LATER TODAY. MODEL GUIDANCE SUGGESTS A COLD FRONT
EXTENDING FROM THE AREA OF LOW PRESSURE WILL SWEEP THROUGH THE
MAJORITY OF THE GULF WITHIN THE NEXT 24 HOURS BRINGING COOLER
CONDITIONS TO THE REGION.

THE CARIBBEAN SEA...
LARGE SUBSIDENT MID TO UPPER RIDGE LIES ABOVE THE ENTIRE ZONE
LIMITING THE DEVELOPMENT OF CONVECTION OR DEEP CLOUDINESS. PATCHES
OF LOW LEVEL CLOUDS ARE STREAMING FROM W TO E ACROSS THE AREA IN
MODERATE TRADE WIND FLOW. THE MOST CONCENTRATED PATCHES ARE FROM 12N
TO 17N E OF 70W AND FROM 12N-18N BETWEEN 82W-86W AND MOVING ONSHORE
OVER EASTERN PORTIONS OF NICARAGUA AND HONDURAS. OVERALL...LITTLE
CHANGE IS EXPECTED UNTIL A FRONT MOVES INTO THE NW CORNER OF THE
CARIBBEAN ON MONDAY.

THE ATLANTIC OCEAN...
A WEAK 1012 MB LOW PRES SYSTEM IS DRIFTING N AND WAS CENTERED NEAR
28N60W. THE LOW-LEVEL CIRCULATION IS EASILY EVIDENT WITH A CLUSTER
OF DEEP CONVECTION FIRING UP ABOUT 90 NM FROM THE LOW LEVEL CENTER
IN THE E SEMICIRCLE. THE MOST RECENT SCATTEROMETER PASS...A 0044 UTC
ASCAT PASS CAPTURED THE CIRCULATION WELL REVEALING WINDS OF UP TO 20
KT MAINLY IN THE EASTERN SEMICIRCLE. NWP MODELS SHOW A CONTINUED
NORTHWARD DRIFT AS IT OPENS INTO A TROUGH OVER THE NEXT DAY OR
TWO...EVENTUALLY BEING ABSORBED BY A MUCH LARGER EXTRATROPICAL LOW
EXPECTED TO INTENSIFY OFF THE MID ATLANTIC COAST TONIGHT AND MONDAY.
OVERCAST MULTILAYERED CLOUDS WITH EMBEDDED SCATTERED SHOWERS/
ISOLATED TSTMS LIE WELL TO THE E OF THE SFC LOW FROM 22N-30N BETWEEN
45W-51W IN AN UPPER DIFFLUENT ZONE.

THE W ATLC W OF 65W IS UNDER SWLY UPPER FLOW AND WEAK SFC RIDGING.
THIS PATTERN IS PRODUCING SCATTERED LOW CLOUDS NE OF THE BAHAMAS.
RADAR...SATELLITE AND LIGHTNING DATA INDICATES THAT SCATTERED
SHOWERS AND TSTMS ARE INCREASING IN COVERAGE OFF THE NE
FLORIDA...GEORGIA AND SOUTH CAROLINA COASTS WELL IN ADVANCE OF A
SHARP UPPER LEVEL TROUGH OVER THE DEEP SOUTH. THIS ACTIVITY IS A
POSSIBLE PRECURSOR TO SURFACE LOW DEVELOPMENT EXPECTED IN THE AREA
LATER TODAY. FURTHER E...MUCH STRONGER SFC RIDGING LIES OVER THE E
ATLC WITH A FAIRLY WELL DEFINED POSITIVELY TILTED UPPER TROUGH
EXTENDING FROM A CYCLONIC CIRCULATION IN THE VICINITY OF THE MADEIRA
ISLANDS/29N18W TO 24N35W. SWIFT MID TO UPPER ZONAL FLOW LIES OVER
THE TROPICS S OUT OF THIS TROUGH CAPPING A VAST AREA OF OVERCAST
HIGH CLOUDS WITH SOME TRANSVERSE BANDING NOTED SUGGESTIVE OF STRONG
UPPER LEVEL TURBULENCE.

$$
COBB



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