[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 141734
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE JUL 14 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
1645 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 35W/36W S OF 18N MOVING W NEAR 20 KT.
THIS WAVE COINCIDES WITH A LOW AMPLITUDE DEEP LATER MOISTURE
MAXIMUM OBSERVED ON TOTAL PRECIPITABLE WATER IMAGERY. VISIBLE
SATELLITE IMAGERY INDICATES CYCLONIC FLOW AROUND THE VICINITY OF
THE WAVE. SCATTERED MODERATE CONVECTION FROM 11N-13N BETWEEN
34W-37W.

A TROPICAL WAVE IS E OF THE LESSER ANTILLES AND EXTENDS FROM
24N61W TO 6N56W MOVING W NEAR 20 KT. THE STRONG LOW LEVEL
EASTERLY JET FOLLOWING THE N PORTION OF THE WAVE IS CONTRIBUTING
TO THE NW-SE TILT OF THE WAVE. A WELL-DEFINED AND
HIGHLY-AMPLIFIED INVERTED-V PATTERN IS EVIDENT IN LOW-LEVEL
CLOUDS BASED ON VISIBLE SATELLITE IMAGERY...COINCIDING WITH A
HIGHLY-AMPLIFIED MAXIMUM IN TOTAL PRECIPITABLE WATER. THE WAVE
IS AT THE LEADING EDGE OF AN ABUNDANT DRY LOW/MID-LEVEL SAHARAN
AIR LAYER SUPPRESSING DEEP CONVECTION IN THE VICINITY OF THE
WAVE. HOWEVER...A SMALL AREA OF SCATTERED MODERATE CONVECTION IS
CONFINED TO THE ITCZ FROM 9N-11N BETWEEN 57W-59W. ISOLATED
SHOWERS/POSSIBLE THUNDERSTORMS ARE ALSO WITHIN 60 NM OF THE WAVE
AXIS N OF 19N...WHICH IS ENHANCED BY UPPER LEVEL DIFFLUENCE.

A TROPICAL WAVE IS ALONG 96W S OF 19N EXTENDING INTO THE E
PACIFIC MOVING W 15-20 KT. DEEP CONVECTION ASSOCIATED WITH THE
WAVE IS CONFINED TO THE E PACIFIC...SEE TWDEP FOR MORE
INFORMATION.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N15W 11N28W 12N38W 8N46W
11N56W 9N62W. A LARGE CLUSTER OF NUMEROUS MODERATE/SCATTERED
STRONG CONVECTION IS FROM 7N-13N BETWEEN 18W-26W...MOST LIKELY
ASSOCIATED WITH THE NEXT TROPICAL WAVE. SCATTERED MODERATE
CONVECTION IS FROM 9N-11N BETWEEN 52W-56W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH IS IN THE NE GULF OF MEXICO EXTENDING FROM
31N84W TO 29N90W. THIS TROUGH IS AHEAD OF A STATIONARY FRONT N
OF THE AREA SUPPORTED BY AN UPPER LEVEL TROUGH OVER THE ERN
CONUS. SURFACE CONVERGENCE NEAR THE SURFACE TROUGH ALONG WITH
UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL TROUGH AND AN
UPPER LEVEL RIDGE DOMINATING THE REMAINDER OF THE GULF ARE
SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 26N-30N E OF
91W. A SURFACE TROUGH IS OVER THE S FLORIDA PENINSULA EXTENDING
FROM 25N82W TO 26N80W AND INTO THE ATLC. SCATTERED
SHOWERS/THUNDERSTORMS ARE WITHIN 100 NM S OF THE TROUGH
INCLUDING THE STRAITS OF FLORIDA. ELSEWHERE...A SURFACE RIDGE
DOMINATES ANCHORED BY A 1017 MB SURFACE HIGH NEAR 24N87W
BRINGING GENERALLY FAIR WEATHER. THIS SURFACE RIDGE IS SUPPORTED
BY AN UPPER LEVEL RIDGE CENTERED AROUND AN UPPER LEVEL HIGH NEAR
27N95W. THE UPPER LEVEL HIGH IS PROVIDING DRY AIR AND SUBSIDENCE
TO THE AREA. ANTICYCLONIC FLOW AROUND THE SURFACE RIDGE IS
SUPPORTING AN AREA OF E WINDS OF 10-15 KT ACROSS THE S HALF OF
THE GULF. EXPECT THE SURFACE RIDGE TO PERSIST OVER THE NEW FEW
DAYS.

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. THESE WINDS WILL REMAIN STRONG OVER THE NEXT
SEVERAL DAYS AS THE SUBTROPICAL RIDGE REMAINS IN PLACE AND A
TROPICAL WAVE MOVES INTO THE AREA. UPPER LEVEL DIFFLUENCE
BETWEEN AN UPPER LEVEL LOW OVER THE NW CARIBBEAN NEAR 17N81W AND
AN UPPER LEVEL HIGH OVER THE E CARIBBEAN NEAR 16N67W ALONG WITH
MOIST SWLY FLOW ALOFT ARE SUPPORTING A LINE OF
SHOWERS/THUNDERSTORMS FROM 15N82W TO 20N74W AND INTO THE
ATLC...INCLUDING ERN CUBA...JAMAICA...AND HISPANIOLA. DEEP LAYER
DRY AIR IS RESULTING IN GENERALLY FAIR WEATHER ACROSS THE E
CARIBBEAN. A TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES
AND SHOULD BE ENTERING THE E CARIBBEAN LATER TODAY.

ATLANTIC OCEAN...
UPPER LEVEL DIFFLUENCE E OF AN UPPER LEVEL TROUGH OVER THE ERN
CONUS IS SUPPORTING A STATIONARY FRONT N OF THE DISCUSSION AREA
ANCHORED BY A 1014 MB SURFACE LOW OFF THE SOUTH CAROLINA COAST.
SCATTERED SHOWERS/THUNDERSTORMS ARE AHEAD OF THE FRONT N OF 29N
W OF 75W. A SURFACE TROUGH EXTENDS ACROSS THE S FLORIDA
PENINSULA ENTERING THE ATLC NEAR 26N80W EXTENDING TO 28N78W.
SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 100 NM S OF THE
TROUGH INCLUDING THE NW BAHAMAS. SCATTERED SHOWERS/THUNDERSTORMS
ARE ALSO FROM 24N-29N BETWEEN 66W-73W. THIS ACTIVITY IS
SUPPORTED BY SURFACE CONVERGENCE NEAR A SURFACE TROUGH EXTENDING
FROM 24N72W TO 29N67W ALONG WITH UPPER LEVEL ATMOSPHERIC
INSTABILITY ASSOCIATED WITH AN UPPER LEVEL TROUGH OVER THE SW N
ATLC EXTENDING FROM THE UPPER LEVEL LOW IN NW CARIBBEAN NEAR
17N81W. A BROAD RIDGE DOMINATES THE REMAINDER OF THE ATLC
ANCHORED BY A 1031 MB SURFACE HIGH NEAR 34N48W AND A 1025 MB
SURFACE HIGH NEAR 34N24W. AN UPPER LEVEL RIDGE DOMINATES THE
ATLC E OF 40W SUPPORTING CONVECTION ALONG THE ITCZ.

$$
WALTON



This weather bulletin was brought to you by:
www.nashvilleweather.net