[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181751
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUL 18 2010

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
1715 UTC...

...TROPICAL WAVES...

TROPICAL WAVE HAS MOVED OFF THE W COAST OF AFRICA ALONG 18W S OF
20N MOVING W NEAR 15 KT. SURFACE WIND OBSERVATIONS FROM DAKAR
SENEGAL INDICATE A NW-E WIND SHIFT INDICATING THE PASSAGE OF THE
WAVE. LOW-MID LEVEL CYCLONIC FLOW IS ALSO EVIDENT IN VISIBLE
SATELLITE IMAGERY AND SATELLITE DERIVED WINDS. A SURGE OF DEEP
LAYER MOISTURE IS ALSO PRESENT IN TOTAL PRECIPITABLE WATER
IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
9N-14N BETWEEN 14W-17W...AND W OF THE WAVE AXIS FROM 3N-9N
BETWEEN 21W-27W.

TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES ALONG 59W S OF
19N MOVING W 15-20 KT. BROAD CYCLONIC FLOW IS ABOUT THE WAVE
AXIS EVIDENT IN SATELLITE IMAGERY. A LARGE AREA OF DEEP LAYER
MOISTURE ALSO ACCOMPANIES THE WAVE SEEN IN TOTAL PRECIPITABLE
WATER IMAGERY. SCATTERED STRONG CONVECTION IS NEAR THE NRN
EXTENT OF THE WAVE FROM 16N-20N BETWEEN 56W-64W ALREADY
IMPACTING PORTIONS OF THE LEEWARD ISLANDS. THIS WAVE WILL LIKELY
BRING HEAVY RAINFALL AND GUSTY WINDS TO THE LEEWARD
ISLANDS...VIRGIN ISLANDS...AND PUERTO RICO OVER THE NEXT COUPLE
OF DAYS.

TROPICAL WAVE IS JUST W OF HISPANIOLA ALONG 74W S OF 20N MOVING
W 15-20 KT. WAVE LIES EMBEDDED WITHIN A LARGE AREA OF DEEP LAYER
MOISTURE THAT IS ACROSS THE CENTRAL CARIBBEAN. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 14N-18N BETWEEN 69W-77W
AFFECTING AREAS S OF HISPANIOLA AND JAMAICA.

TROPICAL WAVE IS OVER THE WRN CARIBBEAN ALONG 82W/83W FROM
13N-23N MOVING W NEAR 15 KT. WAVE LIES EMBEDDED IN A BROAD AREA
OF ENHANCED MOISTURE ACROSS THE WRN CARIBBEAN. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 19N-25N BETWEEN
77W-84W IMPACTING PORTIONS OF THE SW BAHAMAS...WRN CUBA...AND
THE STRAITS OF FLORIDA. SOME OF THIS ACTIVITY IS ALSO ENHANCED
BY AN UPPER LEVEL LOW IN THE SE GULF OF MEXICO.

...ITCZ...

THE ITCZ AXIS IS ALONG 11N19W 7N26W 8N34W 5N47W 7N60W. SCATTERED
MODERATE CONVECTION IS FROM 4N-9N BETWEEN 43W-46W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH REMAINS IN THE SW GULF OF MEXICO FROM 23N93W
ACROSS SRN MEXICO TO 15N94W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE WITHIN 80 NM W OF THE TROUGH AXIS. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO ACROSS THE NRN GULF N OF 28N
BETWEEN 88W-95W AFFECTING THE SRN PORTIONS OF THE GULF COAST
STATES. THIS ACTIVITY IS ENHANCED BY A SHORTWAVE UPPER LEVEL
TROUGH TO THE N EXTENDING FROM CENTRAL GEORGIA TO CENTRAL
LOUISIANA. A TROPICAL WAVE ACROSS THE WRN CARIBBEAN IS ENHANCING
SCATTERED SHOWERS/THUNDERSTORMS THAT EXTEND ACROSS THE STRAITS
OF FLORIDA TO NEAR 25N E OF 84W. SOME OF THIS ACTIVITY IS
ENHANCED BY AN UPPER LEVEL LOW CENTERED NEAR 25N85W. UPPER LEVEL
RIDGING COVERS THE REMAINDER OF THE BASIN CENTERED OVER SRN
ARIZONA. AT THE SURFACE...A RIDGE CONTINUES TO BUILD FROM THE W
ATLC. EXPECT SHOWERS/THUNDERSTORMS TO REMAIN OVER THE SE GULF
AND INTO THE CENTRAL GULF AS THE UPPER LEVEL LOW MOVES WWD.

CARIBBEAN SEA...
SIGNIFICANT MOISTURE AND UNSTABLE CONDITIONS ARE ACROSS MUCH OF
THE CARIBBEAN ASSOCIATED WITH A SERIES OF TROPICAL WAVES. SEE
TROPICAL WAVE SECTION ABOVE FOR MORE DETAILS. BESIDES THE
TROPICAL WAVES...A SURFACE TROUGH HUGS THE YUCATAN PENINSULA
COAST FROM 20N87W TO 14N89W ENHANCING ISOLATED SHOWERS/POSSIBLE
THUNDERSTORMS WITHIN 60 NM EITHER SIDE OF THE AXIS. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO IN THE SW CARIBBEAN S OF
13N BETWEEN 77W-83W ASSOCIATED WITH AN EXTENSION OF THE E
PACIFIC ITCZ ACROSS NICARAGUA TO NRN COLOMBIA. ALOFT...AN UPPER
LEVEL LOW IN THE SE GULF OF MEXICO IS ENHANCING CONVECTION NEAR
THE TROPICAL WAVE IN THE WRN CARIBBEAN. AN UPPER LEVEL RIDGE IS
TO THE E CENTERED OVER ERN CUBA...WHILE AN UPPER LEVEL TROUGH IS
TO THE S FROM NEAR 19N82W TO PANAMA. ANOTHER UPPER LEVEL LOW N
OF PUERTO RICO IS PROVIDING A DIFFLUENT ZONE ALOFT OVER THE
LEEWARD ISLANDS WHICH IS ENHANCING CONVECTION NEAR THE TROPICAL
WAVE JUST E OF THE LESSER ANTILLES. EXPECT CONTINUED SHOWER
ACTIVITY ACROSS MUCH OF THE BASIN AS THE TROPICAL WAVES PROGRESS
WWD BRINGING SIGNIFICANT MOISTURE ACROSS THE AREA.

ATLANTIC OCEAN...
SHOWERS/THUNDERSTORMS ASSOCIATED WITH A TROPICAL WAVE IN THE WRN
CARIBBEAN AND AN UPPER LEVEL LOW IN THE SE GULF OF MEXICO EXTEND
N OF CUBA AFFECTING PORTIONS OF THE WRN BAHAMAS S OF 25N W OF
77W. AN UPPER LEVEL LOW IS SPINNING NEAR 26N67W SUPPORTING A
SURFACE TROUGH ALONG 28N68W TO 19N69W. ISOLATED SHOWERS ARE
WITHIN 200 NM E OF THE TROUGH AXIS...AND 45 NM W OF THE AXIS.
DIFFLUENCE ALOFT TO THE E SIDE OF THIS UPPER LEVEL LOW IS ALSO
ENHANCING CONVECTION NEAR A TROPICAL WAVE ALONG 59W. NUMEROUS
SHOWERS/SCATTERED THUNDERSTORMS ARE FROM 16N-20N BETWEEN
56W-64W. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO FARTHER E FROM
12N-16N BETWEEN 51W-54W...AND FROM 16N-18N BETWEEN 47W-50W. THE
REMAINDER OF THE BASIN IS DOMINATED BY SURFACE RIDGING AROUND A
1026 MB HIGH NEAR 31N56W. ALOFT...AN UPPER LEVEL RIDGE IS
CENTERED NEAR 19N56W WITH AN UPPER TROUGH TO THE E BETWEEN
30W-48W. AN UPPER LEVEL RIDGE COVERS THE FAR E ATLC JUST OFF THE
COAST OF AFRICA.

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

$$

WALTON








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