[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 04 2011

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IN THE CENTRAL TROPICAL ATLC EXTENDS FROM 20N36W
TO 10N40W MOVING W 15-20 KT. VISIBLE SATELLITE IMAGERY SHOWS A
CLASSIC INVERTED-V STRUCTURE IN THE LOW-LEVEL CLOUDS AROUND THE
WAVE AXIS. A 1236 UTC ASCAT SCATTEROMETER PASS ALSO INDICATES
LOW-LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS. THE WAVE ALSO
IS AHEAD OF A SURGE OF DEEP LAYER MOISTURE EVIDENT IN TOTAL
PRECIPITABLE WATER IMAGERY. THE MOISTURE IS WRAPPING AROUND THE
TOP END OF THE WAVE FORMING A DRY SLOT ALONG THE CENTRAL PORTION
OF THE WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
LIMITED TO THE ITCZ AXIS FROM 10N-11N BETWEEN 41W-43W.

TROPICAL WAVE IS IN THE WRN CARIBBEAN EXTENDING FROM 19N80W TO
11N81W MOVING W NEAR 10 KT. THE WAVE IS EMBEDDED WITHIN A LARGE
AREA OF DEEP LAYER MOISTURE THAT IS ACROSS MUCH OF THE
CARIBBEAN. THE WAVE LIES UNDERNEATH AN AREA OF DIFFLUENCE ALOFT
WHICH IS HELPING SUPPORT CONVECTION NEAR THE WAVE. IT IS
DIFFICULT TO DETERMINE WHICH FEATURE IS THE MAIN INFLUENCE ON
THE CONVECTION. SCATTERED MODERATE/STRONG CONVECTION IS E OF THE
WAVE AXIS ACROSS JAMAICA FROM 15N-21N BETWEEN 72W-78W...AND NEAR
THE WAVE AXIS FROM 16N-19N BETWEEN 79W-82W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS W OF THE WAVE AXIS FROM
15N-18N BETWEEN 83W-85W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS OVER AFRICA FROM THE PRIME MERIDIAN
AT 17N ALONG 18N10W 9N13W 7N20W. THE ITCZ CONTINUES FROM 7N20W
ALONG 6N30W 10N39W 9N51W 8N60W. SCATTERED MODERATE/STRONG
CONVECTION IS OFF THE W COAST OF AFRICA FROM 5N-11N BETWEEN
12W-18W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
6N-10N BETWEEN 51W-49W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH COVERS THE GULF OF MEXICO TODAY AROUND AN
UPPER LEVEL LOW CENTERED N OF THE YUCATAN PENINSULA NEAR 23N88W.
THE TROUGH IS SUPPORTING A SURFACE TROUGH IN THE CENTRAL GULF
ALONG 90W FROM 25N-28N. CURRENTLY ISOLATED SHOWERS/THUNDERSTORMS
ARE WITHIN 100 NM E OF THE AXIS. SCATTERED SHOWERS/THUNDERSTORMS
ARE ALSO OVER THE SE GULF FROM 24N-28N BETWEEN 81W-86W. ISOLATED
SHOWERS/THUNDERSTORMS ARE ALSO ACROSS MUCH OF CENTRAL FLORIDA.
THIS ACTIVITY IS MAINLY INFLUENCE BY MOIST AND DIFFLUENT FLOW
ALOFT AROUND THE ERN SIDE OF THE UPPER TROUGH. SHOWER ACTIVITY
IS LIKELY ACROSS THE ERN GULF OVER THE NEXT COUPLE OF DAYS AS
THE UPPER LEVEL LOW REMAINS OVER THE CENTRAL GULF. THE REMAINDER
OF THE BASIN IS UNDER MOSTLY CLEAR SKIES AND LIGHT WINDS. EXPECT
THE SURFACE TROUGH IN THE CENTRAL GULF TO CONTINUE DRIFTING W
WITH LIKELY SHOWERS/THUNDERSTORMS IN ITS VICINITY.

CARIBBEAN SEA...
MOIST SWLY FLOW ALOFT COVERS MUCH OF THE WRN CARIBBEAN BETWEEN
AN UPPER LEVEL TROUGH OVER THE GULF OF MEXICO AND AN UPPER LEVEL
RIDGE COVERING THE CENTRAL AND ERN CARIBBEAN. TOTAL PRECIPITABLE
WATER IMAGERY ALSO INDICATES A LARGE AREA OF DEEP LAYER MOISTURE
IS ACROSS MUCH OF THE BASIN. A TROPICAL WAVE ALONG 80W/81W IS
ALSO AIDING SOME OF THE SHOWER/THUNDERSTORM ACTIVITY. CURRENTLY
SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS JAMAICA AND ERN CUBA
FROM 15N-21N BETWEEN 72W-78W...FROM 16N-19N BETWEEN
79W.82W...AND FROM 15N-18N BETWEEN 83W-85W. ISOLATED
SHOWERS/THUNDERSTORMS ARE ALSO FROM 19N-23N BETWEEN 78W-85W.
MUCH OF THE ERN CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER
INFLUENCED BY SOME DRY AIR ALOFT DRAWING AROUND THE SE SIDE OF
THE AFOREMENTIONED UPPER LEVEL RIDGE. HOWEVER...AN AREA OF
SCATTERED SHOWERS/THUNDERSTORMS IS S OF THE DOMINICAN REPUBLIC
FROM 16N-19N BETWEEN 68W-72W. EXPECT MOIST CONDITIONS AND LIKELY
SHOWER ACTIVITY TO REMAIN OVER THE WRN CARIBBEAN AS THE TROPICAL
WAVE MOVES WWD.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE COVERS THE FAR WRN ATLC EXTENDING FROM THE
CENTRAL CARIBBEAN KEEPING THIS PORTION OF THE BASIN UNDER FAIR
CONDITIONS. HOWEVER...AN UPPER LEVEL LOW IS IMMEDIATELY TO THE E
NEAR 30N69W SUPPORTING A SURFACE TROUGH FROM NEAR 25N70W TO THE
WINDWARD PASSAGE NEAR 19N74W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE FROM 21N-31N BETWEEN 65W-70W...AND FROM
22N-27N BETWEEN 70W-75W. ANOTHER AREA OF SCATTERED
SHOWERS/THUNDERSTORMS IS N OF 27N BETWEEN 60W-63W. THE REMAINDER
OF THE BASIN IS DOMINATED BY SURFACE RIDGING AROUND A PAIR OF
1027 MB SURFACE HIGHS NEAR 34N33W AND 37N46W PROVIDING MOSTLY
FAIR WEATHER ACROSS THE CENTRAL AND ERN ATLC. ALOFT...AN UPPER
LEVEL RIDGE IS BETWEEN 55W-65W. AN UPPER LEVEL TROUGH IS TO THE
E BETWEEN 35W-55W CENTERED AROUND AN UPPER LEVEL LOW NEAR
25N49W. AN UPPER LEVEL RIDGE COVERS THE FAR E ATLC CENTERED NEAR
26N22W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON





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