[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 160526
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU JUL 16 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 0445 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE EXTENDS FROM 16N26W TO 10N28W TO 5N28W MOVING W
10-15 KT. RECENT SATELLITE IMAGERY DEPICTS MID-LEVEL CYCLONIC
CIRCULATION NEAR THIS WAVE. SATELLITE-DERIVED WINDS INDICATE
CYCLONIC CURVATURE IN THE FLOW WITHIN THE 800-600 MB LAYER NEAR
THIS WAVE. SCATTERED MODERATE CONVECTION IS FROM 5N-11N BETWEEN
25W-31W.

A TROPICAL WAVE IS ALONG 43W/44W S OF 16N MOVING W 10-15 KT.
THIS WAVE COINCIDES WITH A LOW AMPLITUDE MAXIMUM IN DEEP LAYER
MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM
CIMSS. THE PRESENCE OF DRY LOW/MID-LEVEL SAHARAN AIR IS LIMITING
DEEP CONVECTION NEAR THIS WAVE. HOWEVER...SCATTERED SHOWERS ARE
OCCURRING WITHIN 300 NM E OF THE WAVE AXIS.

A HIGHLY-AMPLIFIED TROPICAL WAVE IS OVER THE SW NORTH ATLC AND
CENTRAL CARIBBEAN ALONG 74W/75W S OF 24N MOVING W 25-30 KT.
UPPER AIR DATA FROM BARBADOS AND GUADELOUPE AT 15/0000 UTC
INDICATE THAT THE WAVE IS FOLLOWED BY A STRONG EASTERLY 700-600
MB JET...WITH CORE WINDS OF 45-50 KT. THIS WAVE IS ALIGNED WITH
A DISTINCT AND NARROW MAXIMUM IN TOTAL PRECIPITABLE WATER. THE
WAVE IS LEADING AN AREA OF ABUNDANT DRY LOW/MID-LEVEL SAHARAN
AIR...ALONG WITH HAZY CONDITIONS ACROSS MUCH OF THE CENTRAL AND
E CARIBBEAN. THE DRY AIR...ALONG WITH STABLE ATMOSPHERIC
CONDITIONS BENEATH AN UPPER LEVEL RIDGE OVER THE CENTRAL AND E
CARIBBEAN...ARE INHIBITING THE DEVELOPMENT OF DEEP CONVECTION
NEAR THE WAVE...WITH ISOLATED SHOWERS WITHIN 240 NM E OF THE
WAVE AXIS.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 10N26W 9N37W 9N50W 9N61W.
SCATTERED MODERATE CONVECTION IS FROM 7N-11N E OF 17W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-11N BETWEEN
18W-25W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL HIGH IS OVER THE NW GULF OF MEXICO CENTERED NEAR
27N96W WITH A SURFACE RIDGE ACROSS THE CENTRAL GULF AND A 1020
MB SURFACE HIGH NEAR 27N87W. STABLE ATMOSPHERIC CONDITIONS AND
SUBSIDENCE ASSOCIATED WITH THE SURFACE HIGH AND SURFACE RIDGE
ARE RESULTING IN GENERALLY FAIR WEATHER IS PRESENT ACROSS THE
GULF. THE ONLY EXCEPTION IS OVER THE SW GULF...WHERE SCATTERED
SHOWERS AND THUNDERSTORMS ARE OCCURRING S OF 21N BETWEEN
89W-94W. THIS ACTIVITY FORMED EARLIER OVER THE YUCATAN PENINSULA
IN RESPONSE TO ATMOSPHERIC INSTABILITY DRIVEN BY DIURNAL HEATING
OVER LAND. WINDS ARE LIGHT AND VARIABLE IN THE VICINITY OF THE
SURFACE RIDGE ACROSS THE N GULF...WITH ANTICYCLONIC FLOW AROUND
THE RIDGE SUPPORTING A BROAD SWATH OF E WINDS OF 10-15 KT ACROSS
THE S HALF OF THE GULF. THESE CONDITIONS ARE FORECAST TO
CONTINUE DURING THE NEXT SEVERAL DAYS. HOWEVER...NE WINDS UP TO
20 KT ARE FORECAST TO OCCUR DURING THE LATE AFTERNOON AND
EVENING HOURS FOR THE NEXT SEVERAL DAYS NEAR THE COAST OF THE
YUCATAN PENINSULA. LITTLE CHANGE IS EXPECTED OVER THE NEXT
COUPLE DAYS AS BOTH THE UPPER AND SFC RIDGE REMAIN IN PLACE.

CARIBBEAN SEA...
FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE
SUBTROPICAL RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER
NORTHERN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST
OF COLOMBIA. THE QUIKSCAT PASS AROUND 15/2250 UTC INDICATED A
LARGE AREA OF NE TO E WINDS OF 20 TO 30 KT ACROSS THE CENTRAL
CARIBBEAN. COMPUTER MODEL GUIDANCE INDICATES THAT STRONGER WINDS
TO GALE FORCE ARE OCCURRING NEAR THE COAST OF COLOMBIA. THESE
WINDS WILL REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE
SUBTROPICAL RIDGE REMAINS IN PLACE AND A TROPICAL WAVE MOVES
ACROSS THE AREA. IN FACT...GALE CONDITIONS ARE FORECAST TO
CONTINUE DURING THE NEXT COUPLE DAYS NEAR THE COAST OF
COLOMBIA...AS THE LOW LEVEL FLOW STRENGTHENS ACROSS THE
CARIBBEAN AND INTERACTS THE LOCAL TOPOGRAPHICAL VARIATIONS NEAR
THE COAST OF COLOMBIA. ATMOSPHERIC INSTABILITY ASSOCIATED WITH A
WEAK UPPER LEVEL SHORTWAVE TROUGH OVER THE SE CARIBBEAN IS
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS S OF 13N BETWEEN
63W-66W.

ATLANTIC OCEAN...
DEEP LAYER MOISTURE IS COMBINING WITH UPPER LEVEL DIFFLUENCE IN
NORTHWESTERLY FLOW ALOFT TO RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS N OF 28N BETWEEN 60W-67W. SUBSIDENCE AND
GENERALLY FAIR WEATHER ARE PRESENT ACROSS MUCH OF THE CENTRAL
AND E ATLC AROUND A BROAD SURFACE RIDGE WITH A 1023 MB HIGH NEAR
33N19W. ACROSS THE TROPICAL N ATLC...AN UPPER LEVEL RIDGE
EXTENDS FROM 18N16W TO 15N47W 11N61W...WITH UPPER LEVEL
DIVERGENCE SUPPORTING THE CONVECTION ASSOCIATED WITH THE
TROPICAL WAVE EXTENDING FROM 16N26W TO 10N28W TO 5N28W.

$$
COHEN/CANGIALOSI




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