[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 031732
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT JAN 03 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
1715 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 7N11W 4N21W 3N32W 3N43W 2N52W. SCATTERED
MODERATE CONVECTION IS FROM 3N-7N BETWEEN 6W-23W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS S OF 2N BETWEEN THE PRIME
MERIDIAN AND 18W.

...DISCUSSION...

GULF OF MEXICO...
STRONG WESTERLY FLOW ALOFT COVERS MUCH OF THE GULF REGION...WITH
MID/UPPER-LEVEL MOISTURE STREAMING ACROSS THE N GULF. A 120-KT
UPPER LEVEL JET MAXIMUM IS CENTERED OVER N MEXICO AND S TEXAS.
UPPER LEVEL DIVERGENCE IN THE NE QUADRANT OF THIS JET MAXIMUM IS
COMBINING WITH MOISTURE ACROSS THE N GULF TO SUPPORT SCATTERED
SHOWERS AND THUNDERSTORMS N OF 26N BETWEEN 89W-95W. AT THE SAME
TIME...THE RETURN FLOW AROUND A SURFACE HIGH IN THE W ATLC NEAR
30N52W IS BRINGING SE TO S SURFACE WINDS OF 10 TO 20 KT ACROSS
THE GULF REGION. THESE SURFACE WINDS CONTINUE TO ADVECT LOW
LEVEL MOISTURE ACROSS THE GULF REGION...FURTHER ENHANCING THE
AFOREMENTIONED SHOWER AND THUNDERSTORM ACTIVITY. SUBSIDENCE
ASSOCIATED WITH A BROAD UPPER LEVEL RIDGE OVER THE S GULF IS
INHIBITING DEEP CONVECTION ACROSS THE S GULF. FARTHER TO THE
N...A SURFACE FRONT IS DRAPED ACROSS THE CENTRAL PLAINS AND
EXTENDS ACROSS THE CENTRAL ROCKY MOUNTAIN REGION OF THE CONUS.
THIS FRONT IS FORECAST TO ENTER THE NW GULF LATE SUNDAY AS A
COLD FRONT.

CARIBBEAN SEA...
SW TO W UPPER LEVEL FLOW IN ASSOCIATION WITH A BROAD UPPER LEVEL
RIDGE COVERS MUCH OF THE CARIBBEAN SEA. THIS BROAD UPPER RIDGE
IS ANCHORED BY AN UPPER HIGH IN N GUYANA NEAR 7N59W.
SUBSIDENCE...DEEP LAYER DRY AIR...AND STABLE ATMOSPHERIC
CONDITIONS ASSOCIATED WITH THIS UPPER HIGH AND UPPER RIDGE ARE
RESULTING IN FAIR WEATHER CONDITIONS ACROSS MUCH OF THE W AND
CENTRAL CARIBBEAN SEA. GREATER MID/UPPER-LEVEL MOISTURE ACROSS
THE E CARIBBEAN SEA IS SUPPORTING ISOLATED SHOWERS FROM 12N-17N
BETWEEN 62W-70W. ACROSS MUCH OF THE CARIBBEAN SEA...NE TO E
SURFACE WINDS OF 15 TO 25 KT...EXCEPT TO 30 KT ALONG THE COAST
OF COLOMBIA...ARE PRESENT.

ATLANTIC...
ACROSS THE W ATLC...STRONG SW TO W FLOW ALOFT IS PRESENT IN THE
BASE OF AN UPPER TROUGH. DEEP CONVECTION IS BEING INHIBITED
ACROSS THE W ATLC BY DEEP LAYER DRY AIR...AND SUBSIDENCE
ASSOCIATED WITH A 1023 MB SURFACE HIGH NEAR 30N52W. DURING THE
NEXT DAY...A 1022 MB SURFACE HIGH IS FORECAST TO FORM NEAR
29N70W. FARTHER TO THE E...A SURFACE STATIONARY FRONT EXTENDS
FROM 25N77W TO 25N61W TO 28N48W...AND A SURFACE COLD FRONT
EXTENDS FROM 28N48W TO 29N44W TO 32N40W TO NE OF THE DISCUSSION
AREA. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS
WITHIN 90 NM EITHER SIDE OF THESE FRONTS. SUBSIDENCE ASSOCIATED
WITH AN UPPER RIDGE N OF 21N BETWEEN 35W-50W AND A SURFACE RIDGE
EXTENDING FROM A 1028 MB SURFACE HIGH NEAR 34N24W TO NEAR 13N42W
IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF
THE E ATLC. FARTHER TO THE E...AN UPPER TROUGH IS N OF 22N E OF
28W...THOUGH DEEP LAYER DRY AIR IS INHIBITING DEEP CONVECTION
NEAR THIS FEATURE. ACROSS THE TROPICAL ATLC...GENERALLY WESTERLY
FLOW ALOFT IS PRESENT...WITH UPPER LEVEL DIFFLUENCE ENHANCING
THE CONVECTION IN THE VICINITY OF THE ITCZ.

$$
COHEN




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