[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 100541
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI JUL 10 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 28W/29W S OF 16N MOVING W 15-20 KT. A
BROAD AREA OF LOW-MID LEVEL CYCLONIC TURNING IS APPARENT IN
SATELLITE IMAGERY AND IN THE 600-800 MB CLOUD DRIFT WINDS.
QUIKSCAT DATA SHOWS EVIDENCE OF A WEAK CIRCULATION ALONG THE
AXIS NEAR 9N. DESPITE THE FAIR STRUCTURE...CONVECTION IS MINIMAL
AND CONFINED TO THE ITCZ LIKELY SUPPRESSED BY DRY AIR IN PART
ASSOCIATED WITH SAHARAN DUST.

A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES ALONG 18N57W
TO 07N59W MOVING W 20-25 KT. THIS WAVE HAS A BROAD INVERTED V
SHAPE IN ITS LOW-LEVEL CLOUD FIELD WHICH COINCIDES WITH A
MOISTURE MAXIMUM IN TOTAL PRECIPITABLE WATER. SCATTERED MODERATE
CONVECTION EXISTS FROM 9N-13N BETWEEN 56W-62W ENHANCED BY
DIFFLUENT FLOW ALOFT.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 7N31W 6N47W 8N55W.
SCATTERED MODERATE CONVECTION IS FROM 7N-9N E OF 18W. SCATTERED
MODERATE CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN
23W-34W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM
OF THE AXIS BETWEEN 47W-55W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER HIGH OVER W TEXAS IS PROVIDING NLY FLOW AND ADVECTING
DRY AIR OVER MUCH OF THE MIDDLE AND W GULF...HELPING TO SUSTAIN
A SURFACE RIDGE ALONG 26N/27N. AN UPPER TROUGH ALONG THE E COAST
OF THE U.S. EXTENDS INTO THE SE GULF WATERS. INSTABILITY ALONG
THE TROUGH AXIS AND WITHIN THE DIFFLUENT ZONE IS GENERATING
SCATTERED SHOWERS AND TSTMS S OF 29N E OF 86W...AS REVEALED BY
DOPPLER RADAR AND LIGHTNING DATA. SCATTERED SHOWERS AND TSTMS
ARE ALSO OCCURRING OVER THE SRN BAY OF CAMPECHE ASSOCIATED WITH
THE INTERACTION OF A TROPICAL WAVE AND AN UPPER LOW. THIS
ACTIVITY SHOULD DIMINISH BY FRI NIGHT AS BOTH FEATURES TRACK
W. SFC RIDGING IS EXPECTED TO SHIFT NWD OVER THE WEEKEND CAUSING
LIGHT AND VARIABLE FLOW OVER THE N WATERS AND MODERATE ELY WINDS
OVER THE S WATERS.

CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE SURFACE
RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER NORTHERN
SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST OF
COLOMBIA. A QUIKSCAT PASS FROM AROUND 09/2345 UTC CONFIRMED THE
STRONG WINDS NEAR THE COAST OF COLOMBIA AND ENHANCED FLOW IN THE
WINDWARD PASSAGE. THESE WINDS WILL REMAIN STRONG OVER THE NEXT
SEVERAL DAYS AS THE SUBTROPICAL RIDGE STRENGTHENS. ALOFT...AN
UPPER LOW IS CENTERED NEAR JAMAICA. NLY FLOW W OF THE LOW IS
PROMOTING FAIR WEATHER ACROSS THE NW CARIBBEAN. MOIST SLY FLOW
E OF THE LOW AND A DIFFLUENT PATTERN OVER THE SW CARIBBEAN IS
PRODUCING SOME UNSETTLED WEATHER. SCATTERED SHOWERS AND TSTMS
ARE LIKELY S OF 13N W OF 80W AND OVER THE CENTRAL CARIBBEAN FROM
12N-17N BETWEEN 68W-74W. MORE SHOWERS AND TSTMS ARE OCCURRING
OVER THE WINDWARD ISLANDS ASSOCIATED WITH THE TROPICAL WAVE AS
DISCUSSED ABOVE.

ATLANTIC OCEAN...
MAIN AREA OF UNSETTLED WEATHER IS OVER THE WRN PORTION.
SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 27N W OF 74W
ASSOCIATED WITH AN UPPER TROUGH OVER FLORIDA AND A FRONT
EXTENDING FROM A LOW NEAR 33N71W TO N FLORIDA. AS THE UPPER
TROUGH LIFTS N OF THE AREA DURING THE NEXT COUPLE DAYS...THE
FRONT WILL LIKELY BECOME INCREASINGLY DIFFUSE WHILE DRIFTING
SOUTHWARD INTO THE N WATERS. FARTHER E...AN UPPER LOW NEAR
21N64W AND A SFC TROUGH FROM 26N58W TO 20N68W IS ONLY PRODUCING
ISOLATED SHOWERS AND TSTMS WITHIN 240 NM W OF THE SFC TROUGH
AXIS CAPPED BY WIDESPREAD DRY AIR. THE REMAINDER OF THE BASIN IS
RELATIVELY INACTIVE SUPPRESSED BY DEEP LAYER RIDGING AND
ASSOCIATED STABLE AIR. THE SUBTROPICAL RIDGE IS EXPECTED TO
STRENGTHEN SLIGHTLY OVER THE NEXT FEW DAYS INCREASING TRADES
OVER THE TROPICS.

$$
CANGIALOSI





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