[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111115
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON JUL 11 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IN THE TRPCL ATLC EXTENDS FROM NEAR 15N51W TO
6N56W MOVING W 15-20 KT. WAVE CONTINUES TO PRECEDE A SURGE OF
DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY.
SATELLITE IMAGERY ALSO INDICATES LOW LEVEL CYCLONIC FLOW IS
AROUND THE WAVE AXIS. SCATTERED MODERATE/STRONG CONVECTION 180
NM E OF THE AXIS...AND WITHIN 100 NM W OF THE AXIS FROM 8N-10N.

TROPICAL WAVE IN THE WRN CARIBBEAN EXTENDS JUST W OF JAMAICA
FROM 18N79W TO 12N80W MOVING W NEAR 15 KT. WAVE LIES WITHIN A
BROAD AREA OF ENHANCED MOISTURE ACROSS THE WRN CARIBBEAN...AND
JUST W OF THE HIGHEST MOISTURE VALUES IN THE AREA. THE WAVE LIES
UNDER DIFFLUENT FLOW ALOFT WHICH IS HELPING ENHANCE NUMEROUS
STRONG CONVECTION FROM 11N-15N BETWEEN 78W-81W. LARGE CLUSTERS
OF STRONG CONVECTION ARE ALSO FROM 14N-21N BETWEEN 78W-89W. IT
IS HARD TO DETERMINE WHAT IS CAUSED MORE BY THE WAVE OR MORE BY
THE UPPER LEVEL INFLUENCE.

TROPICAL WAVE IN THE BAY OF CAMPECHE EXTENDS FROM 23N95W TO
16N94W MOVING W NEAR 10 KT. WAVE IS EMBEDDED WITHIN AN AREA OF
ENHANCED MOISTURE PRESENT ACROSS THE WRN GULF OF MEXICO. WATER
VAPOR IMAGERY INDICATES DRY AIR IN THE MID AND UPPER LEVELS IS
BEING DRAWN AROUND THE SRN EXTENT OF AN UPPER LEVEL RIDGE OVER
THE ERN GULF WHICH IS LIMITED CONVECTION TO AN AREA OF STRONG
CONVECTION W OF THE AXIS FROM 17N-20N BETWEEN 95W-97W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA FROM THE PRIME MERIDIAN
AT 22N ALONG 23N9W 16N19W 10N28W. THE ITCZ AXIS CONTINUES FROM
10N28W ALONG 8N49W 9N63W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS ALONG A LINE 250 NM S OF THE MONSOON TROUGH/ITCZ
AXIS BETWEEN 17W-32W. SIMILAR ACTIVITY IS FROM 8N-14N BETWEEN
43W-50W.

...DISCUSSION...

GULF OF MEXICO...
A TROPICAL WAVE IN THE SRN BAY OF CAMPECHE IS CAUSING AN AREA OF
CONVECTION OVER SRN MEXICO. SEE TROPICAL WAVE SECTION ABOVE FOR
MORE DETAILS. THE REMAINDER OF THE BASIN IS DOMINATED BY WEAK
SURFACE RIDGING AROUND A 1017 MB HIGH OFF THE NW COAST OF
FLORIDA NEAR 28N84W. THIS RIDGE IS SUPPORTED BY AN UPPER LEVEL
RIDGE CENTERED OVER NRN ALABAMA. AN UPPER LEVEL TROUGH COVERS
THE FAR WRN GULF CENTERED OVER NRN TEXAS. DRY AIR IS WRAPPING
AROUND THE SRN EXTENT OF THE UPPER RIDGE ACROSS THE FLORIDA
STRAITS AND INTO THE CENTRAL GULF WHICH IS SUPPORTING FAIR
WEATHER ACROSS MUCH OF THE BASIN. A SHORTWAVE UPPER LEVEL TROUGH
PERTURBS INTO THE UPPER RIDGE FROM THE W ATLC AND ACROSS NRN
FLORIDA. THIS TROUGH COMBINED WITH THE EFFECTS OF ENHANCED
MOISTURE IS CURRENTLY ENHANCING AN AREA OF CLOUDINESS AND
ISOLATED SHOWERS ACROSS CENTRAL FLORIDA FROM CAPE CANAVERAL TO
BETWEEN SARASOTA AND FORT MYERS. RADAR IMAGERY ALSO INDICATES
ISOLATED SHOWERS ARE MOVING ACROSS THE FLORIDA KEYS WITH SOME
STRONGER ACTIVITY IN THE BIG BEND OF FLORIDA. EXPECT THE
TROPICAL WAVE TO MOVE WWD TOWARDS MEXICO AS WEAK SURFACE RIDGING
CONTINUES ACROSS THE REMAINDER OF THE BASIN.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH COVERS THE NW CARIBBEAN CENTERED NEAR
17N86W. AN UPPER LEVEL RIDGE COVERS THE CENTRAL CARIBBEAN
CENTERED N OF THE COLOMBIA/VENEZUELA BORDER. THIS PATTERN IS
CREATING DIFFLUENT FLOW ALOFT ACROSS MUCH OF THE WRN CARIBBEAN.
THIS AREA OF DIFFLUENCE IS ALSO ABOVE A TROPICAL WAVE W OF
JAMAICA ALONG 79W/80W. THIS COMBINATION IS SUPPORTING CLUSTERS
OF STRONG SHOWERS/THUNDERSTORMS FROM 11N-21N BETWEEN
78W-85W...FROM 14N-18N BETWEEN 85W-89W...AND N OF JAMAICA FROM
18N-20N BETWEEN 75W-77W. SIMILAR ACTIVITY IS S OF 11N ACROSS
COSTA RICA AND PANAMA INFLUENCED BY THE MONSOON TROUGH THAT
EXTENDS FROM THE E PACIFIC ACROSS NRN COSTA RICA TO NRN
COLOMBIA. MODEL GUIDANCE STILL INDICATES THAT THE MONSOON TROUGH
WILL BEGIN TO LIFT N LATER IN THE WEEK ACROSS SRN MEXICO AND THE
NRN CENTRAL CARIBBEAN WHICH WILL CONCENTRATE SHOWER ACTIVITY
OVER THESE AREAS. THE ERN CARIBBEAN IS UNDER MOSTLY FAIR
CONDITIONS IN ELY 20-25 KT TRADEWINDS. A FEW EMBEDDED SHOWERS
ARE NOTES IN THE ELY FLOW ACROSS THE NE CARIBBEAN WITH A CLUSTER
OF THUNDERSTORMS CURRENTLY S OF ERN DOMINICAN REPUBLIC. EXPECT
CONTINUED SHOWER ACTIVITY ACROSS THE WRN CARIBBEAN AS THE
TROPICAL WAVE MOVES WWD. A TROPICAL WAVE E OF THE LESSER
ANTILLES IS EXPECTED TO IMPACT THE BASIN LATER IN THE WEEK.

ATLANTIC OCEAN...
WEAK SURFACE RIDGING DOMINATES THE WRN ATLC MAINTAINING MOSTLY
FAIR CONDITIONS. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE
CENTERED OVER NRN ALABAMA WITH ANTICYCLONIC CIRCULATION
EXTENDING TO 58W. HOWEVER...A SHORTWAVE UPPER TROUGH EXTENDS
INTO THE UPPER RIDGE ALONG 37N56W 30N70W 29N82W. THIS UPPER
TROUGH IS SUPPORTING AN AREA OF ISOLATED SHOWERS/POSSIBLE
THUNDERSTORMS N OF 29N BETWEEN 59W-80W. AN UPPER LEVEL LOW IS
SPINNING IN THE CENTRAL ATLC NEAR 31N54W SUPPORTING A SURFACE
TROUGH ALONG 29N55W TO 24N57W. SCATTERED SHOWERS ARE WITHIN 120
NM E OF THE AXIS. THE REMAINDER OF THE BASIN IS DOMINATED BY
SURFACE RIDGING AROUND A 1029 MB HIGH NEAR 36N37W PROVIDING FAIR
WEATHER. ALOFT...AN UPPER LEVEL RIDGE COVERS THE MAJORITY OF THE
ERN ATLC CENTERED SW OF THE AZORES ISLANDS. A NARROW UPPER LEVEL
TROUGH EXTENDS FROM THE CANARY ISLANDS TO JUST N OF THE CAPE
VERDE ISLANDS CAUSING NO ACTIVE WEATHER IN THE DISCUSSION
AREA.

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

$$
WALTON





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