[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON JAN 19 2009

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
1645 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 6N9W 3N15W 1N22W CROSSING THE
EQUATOR NEAR 35W AND EXTENDING INTO NE BRAZIL NEAR 3S48W.
SCATTERED MODERATE CONVECTION IS S OF 4N BETWEEN 8W-20W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF 1N BETWEEN
22W-26W. SCATTERED MODERATE CONVECTION IS S OF 4N BETWEEN
28W-41W. NUMEROUS MODERATE CONVECTION IS FROM 1N-7N BETWEEN
46W-53W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYER TROUGH OVER THE E CONUS AND W ATLC EXTENDS INTO THE
N GULF REGION...WITH STRONG WESTERLY FLOW ALOFT IN THE BASE OF
THIS TROUGH AFFECTING MUCH OF THE GULF REGION. THIS DEEP TROUGH
IS SUPPORTING A SURFACE COLD FRONT. AT 19/1500 UTC...THIS COLD
FRONT EXTENDS FROM THE CENTRAL FLORIDA PENINSULA NEAR 28N81W TO
24N87W TO THE W GULF NEAR 21N96W AND IS DISSIPATING W OF 91W.
LOW LEVEL CONVERGENCE IS SUPPORTING ISOLATED SHOWERS WITHIN
60 NM EITHER SIDE OF THE COLD FRONT. HOWEVER...STABLE
ATMOSPHERIC CONDITIONS AND DEEP LAYER DRY AIR ARE GENERALLY
INHIBITING DEEP CONVECTION ACROSS MUCH OF THE GULF REGION.
SURFACE WINDS ACROSS THE GULF ARE W TO NW AT SPEEDS OF 20 TO
30 KT...EXCEPT 15 TO 20 KT ACROSS THE SW GULF. A SECOND...
FAST-MOVING SURFACE COLD FRONT IS APPROACHING THE NW GULF. THIS
FRONT IS FORECAST TO MOVE SE OF THE GULF REGION AROUND SUNSET ON
TUESDAY. RELATIVELY COOLER AND DRIER CONDITIONS ARE IN THE WAKE
OF THE COLD FRONTS.

CARIBBEAN SEA...
DEEP LAYER DRY AIR AND STABLE ATMOSPHERIC CONDITIONS ARE
AFFECTING MUCH OF THE CARIBBEAN SEA...WITH A BROAD UPPER LEVEL
RIDGE IN PLACE ACROSS THE W AND CENTRAL CARIBBEAN. AS A
RESULT...GENERALLY FAIR WEATHER IS PRESENT ACROSS MUCH OF THE
CARIBBEAN. HOWEVER...A SURFACE TROUGH EXTENDS FROM W HAITI NEAR
19N74W TO 14N77W TO 10N77W. SURFACE OBSERVATIONS INDICATE A
REGION OF CYCLONIC CURVATURE IN THE SURFACE WIND FIELD IN THE
VICINITY OF THIS SURFACE TROUGH...WHERE VISIBLE SATELLITE
IMAGERY DEPICTS CYCLONIC MOTION OF LOW LEVEL CLOUDS. LOW LEVEL
CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER
SIDE OF THIS SURFACE TROUGH. THE AFOREMENTIONED COLD FRONT THAT
IS APPROACHING THE NW GULF IS FORECAST TO MOVE THROUGH THE
YUCATAN CHANNEL LATE TUESDAY.

ATLANTIC OCEAN...
STRONG WESTERLY AND SOUTHWESTERLY FLOW ALOFT IS PRESENT ACROSS
THE W ATLC...WITH A DEEP TROUGH OVER THE E CONUS AND W ATLC. THE
DEEP TROUGH IS ASSOCIATED WITH A SURFACE COLD FRONT THAT EXTENDS
FROM THE CENTRAL FLORIDA PENINSULA NEAR 28N81W TO 30N79W TO
32N76W TO NE OF THE DISCUSSION AREA. LOW LEVEL CONVERGENCE IS
SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THIS
COLD FRONT. ADDITIONALLY...A SECOND COLD FRONT IS FORECAST TO
MOVE OFF THE SE UNITED STATES COAST LATE TONIGHT...REACHING A
LINE FROM 31N70W TO THE FLORIDA STRAITS AROUND SUNSET TUESDAY.
ADDITIONALLY...GALE FORCE WINDS ARE OCCURRING ACROSS PORTIONS OF
THE SW N ATLC. THE AFOREMENTIONED DEEP TROUGH IS ALSO ASSOCIATED
WITH A SURFACE TROUGH THAT EXTENDS FROM 22N72W TO 25N68W...A
SURFACE STATIONARY FRONT THAT EXTENDS FROM 25N68W TO 31N60W...
AND A SURFACE COLD FRONT THAT EXTENDS FROM 31N60W TO 32N59W TO N
OF THE DISCUSSION AREA. LOW LEVEL CONVERGENCE IS SUPPORTING
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 90 NM EITHER
SIDE OF THIS SURFACE TROUGH...STATIONARY FRONT...AND COLD FRONT.
THIS ACTIVITY IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE
ASSOCIATED WITH AN UPPER LEVEL JET MAXIMUM LOCATED NORTH OF THE
DISCUSSION AREA. FARTHER TO THE E...AN UPPER HIGH IS CENTERED
NEAR 23N30W...WITH A 1036 MB SURFACE HIGH CENTERED NEAR 32N37W.
SUBSIDENCE AND STABLE ATMOSPHERIC CONDITIONS ASSOCIATED WITH THE
UPPER HIGH AND SURFACE HIGH ARE RESULTING IN GENERALLY FAIR
WEATHER ACROSS MUCH OF THE CENTRAL AND E ATLC. ACROSS THE
TROPICAL ATLC...WESTERLY FLOW ALOFT IS PRESENT...WITH UPPER
LEVEL DIVERGENCE ENHANCING THE CONVECTION ASSOCIATED WITH THE
ITCZ.

$$
COHEN




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