[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101751
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 17N29W TO 5N31W MOVING W 15-20 KT.
SATELLITE IMAGERY INDICATES THE WAVE COINCIDES WITH A BROAD AREA
OF LOW/MID-LEVEL CYCLONIC TURNING. SATELLITE-DERIVED WINDS
INDICATE CYCLONIC CURVATURE IN THE FLOW WITHIN THE 600-800 MB
LAYER. DEEP CONVECTION NEAR THE WAVE IS BEING SUPPRESSED BY THE
PRESENCE OF LOW TO MIDDLE LEVEL DRY SAHARAN AIR LAYER...WITH
DEEP CONVECTION CONFINED MAINLY NEAR THE ITCZ AXIS FROM 5N-8N
BETWEEN 30W-36W.

A TROPICAL WAVE IS ACROSS THE LESSER ANTILLES AND EXTENDS FROM
22N60W TO 9N63W MOVING W 20-25 KT. THIS WAVE IS EMBEDDED WITHIN
A BROAD HIGH AMPLITUDE INVERTED-V CLOUD SIGNATURE...AS WELL AS A
MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE
WATER PRODUCT FROM CIMSS. WHILE THIS WAVE CONTINUES TO INTERACT
WITH THE SAHARAN AIR LAYER OVER THE ERN CARIBBEAN...CONVECTION
IS CONFINED TO SCATTERED SHOWERS E OF 65W AND OVER THE LESSER
ANTILLES.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 13N16W 10N28W 7N34W 6N47W 9N60W.
SCATTERED MODERATE CONVECTION IS FROM 5N-8N BETWEEN 13W-36W.
SIMILAR CONVECTION IS FROM 6N-11N BETWEEN 51W-61W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER HIGH OVER W TEXAS IS PROVIDING N-NE FLOW ALOFT AND
ADVECTING DRY AIR OVER MUCH OF THE MIDDLE AND WRN GULF...HELPING
TO SUSTAIN A SURFACE RIDGE ALONG 27N. AN UPPER TROUGH ALONG THE
E COAST OF THE U.S. EXTENDS ACROSS THE FLORIDA PENINSULA AND
INTO THE SE GULF WATERS. INSTABILITY ALONG THE TROUGH AXIS AND
WITHIN THE DIFFLUENT ZONE IS GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS S OF 28N E OF 85W...FOCUSED ALONG A WEAK SURFACE
TROUGH THAT EXTENDS FROM ST. AUGUSTINE FLORIDA INTO THE
E/CENTRAL GULF NEAR 28N85W. SCATTERED SHOWERS AND TSTMS ARE ALSO
OCCURRING S OF 25N W OF 93W OVER THE SW GULF ASSOCIATED WITH THE
INTERACTION OF A SURFACE TROUGH ALONG 24N95W TO 18N96W AND AN
INVERTED UPPER TROUGH MOVING ACROSS CENTRAL INTERIOR MEXICO. THE
SURFACE RIDGING IS EXPECTED TO SHIFT NWD OVER THE WEEKEND
CAUSING LIGHT AND VARIABLE FLOW OVER THE NRN WATERS AND MODERATE
ELY WINDS OVER THE SRN WATERS.

CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE SURFACE
RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER NRN SOUTH
AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST OF COLOMBIA. AN
EARLIER QUIKSCAT PASS AROUND 1100 UTC CONFIRMED THE STRONG WINDS
NEAR THE COAST OF COLOMBIA UP TO 30 KT. THESE WINDS WILL REMAIN
STRONG OVER THE NEXT SEVERAL DAYS AS THE SUBTROPICAL RIDGE
STRENGTHENS. ALOFT...AN UPPER LOW IS CENTERED NE OF JAMAICA NEAR
18N76W. 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 OBSERVED S OF 13N W OF
79W TO OVER INTERIOR NICARAGUA AND HONDURAS AS WELL AS ISOLATED
SHOWERS AND TSTMS OVER THE N/CENTRAL CARIBBEAN FROM 18N-21N
BETWEEN 74W-78W. MORE SHOWERS AND TSTMS ARE OCCURRING ACROSS THE
ERN CARIBBEAN AND LESSER ANTILLES E OF 65W IN ASSOCIATION WITH
THE TROPICAL WAVE DISCUSSED ABOVE.

ATLANTIC OCEAN...
MAIN AREA OF UNSETTLED WEATHER IS OVER THE WRN PORTION OF THE
BASIN WITH SCATTERED SHOWERS AND TSTMS OCCURRING W OF 74W
ASSOCIATED WITH AN UPPER TROUGH OVER FLORIDA AND A FRONTAL
BOUNDARY EXTENDING ALONG 32N72W TO NEAR ST. AUGUSTINE FLORIDA
AND FOCUSED ON A 1017 MB SURFACE LOW CENTERED NEAR 31N80W. AS
THE UPPER TROUGH LIFTS N OF THE AREA DURING THE NEXT COUPLE
DAYS...THE FRONT IS EXPECTED TO BECOME DIFFUSE WHILE DRIFTING
SOUTHWARD INTO THE N WATERS. FARTHER E...AN UPPER LOW NEAR
23N63W AND A SURFACE TROUGH FROM 26N59W TO 22N69W IS PRODUCING
SCATTERED SHOWERS AND TSTMS WITHIN 120 NM W OF THE SURFACE
TROUGH AXIS CAPPED BY WIDESPREAD DRY AIR. THE REMAINDER OF THE
BASIN IS RELATIVELY INACTIVE SUPPRESSED BY DEEP LAYER RIDGING
AND ASSOCIATED STABLE AIR ANCHORED ON A PAIR OF 1026 MB SURFACE
HIGHS CENTERED NEAR 31N41W AND 30N49W. THIS SUBTROPICAL RIDGE IS
FORECAST TO STRENGTHEN SLIGHTLY OVER THE NEXT FEW DAYS
INCREASING TRADES OVER THE TROPICS.

$$
HUFFMAN




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