[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071733
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 07 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
1700 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 35W S OF 17N MOVING W NEAR 13 KT. THIS
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY AND
SATELLITE DERIVED WINDS INDICATE LOW/MID-LEVEL CYCLONIC FLOW IN
THE VICINITY OF THE WAVE AXIS. A DRY SAHARAN AIR LAYER IS JUST E
OF THE WAVE AXIS INHIBITING DEEP CONVECTION NEAR THE WAVE.

A TROPICAL WAVE IS ALONG 53W S OF 15N MOVING W 15-20 KT. THIS
WAVE IS LOW AMPLITUDE AND EMBEDDED WITHIN THE ITCZ. WAVE
POSITION IS BASED MAINLY ON CONTINUITY. HOWEVER...RECENT
SATELLITE DERIVED WINDS DO SHOW SLIGHT LOW/MID-LEVEL CYCLONIC
FLOW NEAR THE WAVE AXIS. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS LIMITED TO THE ITCZ FROM 9N-12N BETWEEN 52W-57W.

A TROPICAL WAVE IS ALONG 70W S OF 20N MOVING W NEAR 13 KT. THIS
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS
CURRENTLY ASSOCIATED WITH THIS WAVE. HOWEVER...SCATTERED SHOWERS
ARE FROM 13N-17N BETWEEN 68W-72W...AND FROM 18N-21N BETWEEN
69W-71W.

A TROPICAL WAVE IS ALONG 89W S OF 21N MOVING W 15-20 KT. THIS
WAVE LIES IN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. THIS WAVE IS UNDER A DIFFLUENT
PATTERN ALOFT ENHANCING SCATTERED MODERATE/ISOLATED STRONG
CONVECTION FROM 10N-15N BETWEEN 91W-94W.

...ITCZ...
70
THE ITCZ AXIS IS CENTERED ALONG 14N17W 11N25W 14N39W 11N52W
10N64W. SCATTERED MODERATE CONVECTION IS FROM 12N-17N BETWEEN
20W-23W. SIMILAR CONVECTION IS FROM 7N-12N BETWEEN 24W-31W. A
SURFACE TROUGH IS EMBEDDED IN THE ITCZ EXTENDING FROM 15N43W TO
9N48W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
10N-13N BETWEEN 45W-50W...ENHANCED BY THE SURFACE TROUGH.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ALSO FROM
9N-11N BETWEEN 58W-61W.

...DISCUSSION...

GULF OF MEXICO...
SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS MUCH OF THE GULF OF
MEXICO ESPECIALLY FROM 21N-26N W OF 91W...AND FROM 25N-29N
BETWEEN 83W-89W. THIS ACTIVITY IS ENHANCED BY SURFACE
CONVERGENCE NEAR A SURFACE TROUGH EXTENDING ACROSS THE CENTRAL
GULF FROM 23N90W TO 29N84W. AN UPPER LEVEL TROUGH EXTENDS ACROSS
THE GULF FROM AN UPPER LEVEL LOW NEAR 22N93W TO THE FLORIDA
PANHANDLE NEAR 30N85W. UPPER LEVEL DIFFLUENCE BETWEEN THIS UPPER
LEVEL TROUGH AND UPPER LEVEL RIDGING TO THE W CENTERED OVER NRN
MEXICO NEAR 28N106W...AND TO THE E CENTERED N OF CUBA NEAR
24N78W...IS ALSO SUPPORTING THE SHOWERS/THUNDERSTORMS. A SECOND
SURFACE TROUGH IS ACROSS S FLORIDA EXTENDING FROM 25N82W TO
28N80W GENERATING SCATTERED SHOWERS/THUNDERSTORMS FROM 25N-27N
BETWEEN 80W-84W. LIGHT WINDS ARE ACROSS MUCH OF THE GULF
REACHING UP TO 15 KT IN THE SW GULF. EXPECT A TROPICAL WAVE
CURRENTLY OVER THE YUCATAN PENINSULA TO ENTER THE BAY OF
CAMPECHE LATER TODAY.

CARIBBEAN SEA...
AN UPPER LEVEL DIFFLUENT PATTERN IS OVER THE NW CARIBBEAN
BETWEEN AN UPPER LEVEL LOW IN THE SRN GULF OF MEXICO NEAR
22N93W...AN UPPER LEVEL HIGH N OF CUBA NEAR 24N78W...AND AN
UPPER LEVEL HIGH OFF THE COAST OF NICARAGUA NEAR 13N83W. THIS
DIFFLUENT PATTERN IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS
OVER ERN CUBA N OF 21N BETWEEN 80W-85W...AS WELL AS OFF THE
COASTS OF HONDURAS AND BELIZE FROM 16N-19N W OF 84W. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO ACROSS THE SW CARIBBEAN S OF 13N
BETWEEN 75W-85W. THIS ACTIVITY IS ENHANCED BY SURFACE
CONVERGENCE NEAR THE E PACIFIC ITCZ AND A 1010 MB SURFACE LOW
OVER COLUMBIA NEAR 8N77W. A TROPICAL WAVE ALONG 70W IS
SUPPORTING SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS FROM 13N-17N
BETWEEN 68W-72W...AND FROM 18N-21N BETWEEN 69W-71W. FRESH TO
STRONG TRADE WINDS ARE ACROSS MUCH OF THE E AND CENTRAL
CARIBBEAN. EXPECT THE TROPICAL WAVE ALONG 70W TO CONTINUE
WWD...AND ANOTHER TROPICAL WAVE CURRENTLY ALONG 53W WILL ENTER
THE ERN CARIBBEAN OVER THE WEEKEND.

ATLANTIC OCEAN...
SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS THE NW ATLC NW OF A
LINE FROM 23N79 TO 32N74WW. THIS ACTIVITY IS ENHANCED BY SURFACE
CONVERGENCE AHEAD OF A COLD FRONT N OF THE DISCUSSION AREA. NEAR
S FLORIDA AND THE BAHAMAS THIS ACTIVITY IS ENHANCED BY SURFACE
CONVERGENCE NEAR A SURFACE TROUGH ACROSS S FLORIDA EXTENDING
FROM 25N82W TO 28N80W. UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER
LEVEL TROUGH OVER THE ERN CONUS AND AN UPPER LEVEL HIGH N OF
CUBA NEAR 24N78W IS ALSO ENHANCING THIS ACTIVITY. A SECOND
SURFACE TROUGH IS N OF THE ERN BAHAMAS EXTENDING FROM 24N72W TO
29N71W. SURFACE CONVERGENCE NEAR THIS TROUGH IS SUPPORTING
ISOLATED SHOWERS WITHIN 150 NM W OF THE TROUGH AXIS. ISOLATED
SHOWERS ARE ALSO IN THE CENTRAL ATLC FROM 28N-32N BETWEEN
41W-49W ENHANCED BY AN UPPER LEVEL LOW NEAR 27N43W. THE
REMAINDER OF THE ATLC IS DOMINATED BY A BROAD SURFACE RIDGE
ANCHORED BY A 1028 MB SURFACE HIGH NEAR 35N44W. ACROSS THE
TROPICAL ATLC...AN UPPER LEVEL HIGH IS CENTERED E OF THE LESSER
ANTILLES NEAR 17N58W ENHANCING CONVECTION ALONG THE WRN PORTION
OF THE ITCZ. A SECOND UPPER LEVEL RIDGE CENTERED NEAR 22N25W IS
ENHANCING CONVECTION ALONG THE ERN PORTION OF THE ITCZ.

$$
WALTON





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