[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 302351
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUL 30 2012

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 17N36W TO A 1009 MB LOW AT 9N36W. THE
WAVE/LOW IS MOVING W AT ABOUT 10-15 KT. THE WAVE IS FAIRLY LOW
AMPLITUDE WITH A WEAK SIGNAL IN TOTAL PRECIPITABLE WATER.
HOWEVER...AN ANALYSIS OF THE SAHARAN AIR LAYER SHOWS A CLEARING
IN THE WIDESPREAD DUST NEAR THE WAVE AXIS INDICATING ITS
PRESENCE. THE SURFACE LOW IS EMBEDDED WITHIN THE MONSOON TROUGH
AND HAS BEEN FOR THE PAST SEVERAL DAYS. MODEL GUIDANCE INDICATES
THAT THE LOW WILL PERSIST FOR THE NEXT FEW DAYS AND THE SYSTEM
WILL BE MONITORED FOR POSSIBLE DEVELOPMENT.
CURRENTLY...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
LIMITED TO THE MONSOON TROUGH REGION FROM 6N-10N BETWEEN 35W-41W.

ACTIVE TROPICAL WAVE IS ACROSS THE EASTERN CARIBBEAN FROM 21N62W
TO 11N64W MOVING W AT 15-20 KT. TOTAL PRECIPITABLE WATER IMAGERY
INDICATES THAT THE WAVE LIES WITHIN A SURGE OF DEEP LAYER
MOISTURE WITH MAXIMUM VALUES NEAR THE AXIS. SURFACE OBSERVATIONS
ALSO INDICATE LOW LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS.
CURRENTLY SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
16N-20N BETWEEN 59W-67W COVERING MUCH OF THE NE CARIBBEAN
ISLANDS.

TROPICAL WAVE IS MOVING INTO CENTRAL AMERICAN AND THE NW
CARIBBEAN ALONG 19N82W TO 10N84W TRAVELING W AT 20-25 KT. THE
WAVE ALIGNS WITH A SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL
PRECIPITABLE WATER IMAGERY. THE WAVE ALSO IS MOVING UNDERNEATH
AN AREA OF DIFFLUENCE ALOFT WHICH IS ENHANCING CONVECTION.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 14N-17N
BETWEEN 84W-88W ACROSS MUCH OF HONDURAS. SIMILAR ACTIVITY IS TO
THE S ACROSS PORTIONS OF COSTA RICA AND PANAMA...BUT THIS
ACTIVITY IS MORE TIED TO THE DIFFLUENCE ALOFT AND THE MONSOON
TROUGH. IT WILL BE DISCUSSED IN THE CARIBBEAN SECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
SENEGAL AT 15N17W OVER ATLC WATERS ALONG 10N28W 11N32W TO A 1009
MB LOW ASSOCIATED WITH A WAVE AT 9N36W TO 8N48W. THE ITCZ BEGINS
AT 8N48W CONTINUING TO 12N60W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 8N-11N BETWEEN 18W-22W. ISOLATED
MODERATE CONVECTION IS FROM 7N-10N BETWEEN 28W-32W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-9N BETWEEN
41W-49W.

...DISCUSSION...

GULF OF MEXICO...
SCATTERED SHOWERS/THUNDERSTORMS COVER MUCH OF THE NE GULF AND
THE FLORIDA PENINSULA ASSOCIATED WITH AN UPPER LEVEL TROUGH
EXTENDING DOWN THE EASTERN SEABOARD. THE UPPER TROUGH SUPPORTS A
PAIR OF SURFACE TROUGHS...AS OF 2100 UTC. ONE EXTENDS FROM THE W
ATLC ACROSS CENTRAL FLORIDA ALONG 29N81W TO 27N84W. THE SECOND
EXTENDS FROM GEORGIA TO 31N84W TO 30N89W. SOME ISOLATED
SHOWERS/THUNDERSTORMS EXTEND INTO THE CENTRAL PORTIONS OF THE
GULF. ACROSS THE REMAINDER OF THE BASIN...SURFACE RIDGING
DOMINATES AROUND A 1019 MB HIGH CENTERED NEAR 27N93W. LIGHT
ANTI-CYCLONIC WINDS ARE AROUND THE HIGH. AN UPPER LEVEL RIDGE
COVERING THE CENTRAL CONUS SUPPORTS THE SURFACE HIGH. THE SRN
GULF IS COVERED BY A PAIR OF UPPER LEVEL LOWS. ONE IS OVER
WESTERN CUBA NEAR 23N82W...WHILE THE SECOND IS CENTERED OVER
CENTRAL MEXICO NEAR 22N102W. NEITHER UPPER LOW IS CAUSING
SIGNIFICANT WEATHER OVER THE BASIN. EXPECT A SIMILAR PATTERN
OVER THE NEXT COUPLE OF DAYS.

CARIBBEAN SEA...
A PAIR OF TROPICAL WAVES ARE CAUSING ACTIVE WEATHER IN THE
CARIBBEAN THIS EVENING. A WAVE IS ACROSS THE NW CARIBBEAN INTO
CENTRAL AMERICA ACROSS HONDURAS AND NICARAGUA.
SHOWERS/THUNDERSTORMS ARE MAINLY ACROSS WESTERN HONDURAS.
SCATTERED SHOWERS/THUNDERSTORMS ALSO COVER THE SW CARIBBEAN
INCLUDING COSTA RICA AND PANAMA ASSOCIATED WITH THE MONSOON
TROUGH S OF BOTH COUNTRIES ALONG WITH DIFFLUENCE ALOFT BETWEEN
BROAD INVERTED UPPER TROUGHING OVER THE E PACIFIC AND AN UPPER
LEVEL RIDGE OVER THE CENTRAL CARIBBEAN. AN UPPER LEVEL LOW
CENTERED OVER WESTERN CUBA IS ALSO ENHANCING THE ACTIVITY NEAR
THE WAVE AS WELL AS SHOWERS/THUNDERSTORMS OVER MUCH OF CUBA
HISPANIOLA. DRY AIR ALOFT IS KEEPING THE CENTRAL CARIBBEAN UNDER
FAIR CONDITIONS. THE EASTERN CARIBBEAN IS IMPACTED BY THE SECOND
TROPICAL WAVE WHICH EXTENDS ALONG 64W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE ACROSS THE NRN LEEWARD
ISLANDS WITH THE SE CARIBBEAN REMAINING MOSTLY DRY. STATIONS
ACROSS THE BASIN CONTINUE TO REPORT DUST EXCEPT IN AREAS WHERE
THERE ARE SHOWERS/THUNDERSTORMS. EXPECT THE WESTERN WAVE TO MOVE
OUT OF THE BASIN...WHILE THE EASTERN WAVE CONTINUES INTO THE
CENTRAL CARIBBEAN.

ATLANTIC OCEAN...
SHOWERS/THUNDERSTORMS ASSOCIATED WITH AN UPPER LEVEL TROUGH
EXTENDING DOWN THE EASTERN SEABOARD ARE ACROSS THE FLORIDA
PENINSULA AND OFFSHORE WATERS. SOME OF THESE ARE NEAR A SURFACE
TROUGH ALONG 32N77W TO 29N81W. AN UPPER LEVEL LOW CENTERED NEAR
28N68W IS ALSO CAUSING SHOWERS/THUNDERSTORMS FROM 27N-29N
BETWEEN 70W-73W. THE REMAINDER OF THE W ATLC IS COVERED BY
SURFACE RIDGING AROUND A SERIES OF HIGH CENTERED N OF THE AREA.
THEY ARE ALL SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR
34N55W. ANOTHER UPPER LEVEL LOW IS FARTHER E CENTERED NEAR
28N42W SUPPORTING A WEAK 1016 MB LOW NEAR 31N46W. ISOLATED
SHOWERS ARE SW OF THE LOW. THE REMAINDER OF THE EASTERN ATLC IS
DOMINATED BY SURFACE RIDGING EXTENDING FROM THE N THAT IS
PROVIDING FAIR CONDITIONS ACROSS MUCH OF THE AREA. IT IS
SUPPORTED BY THE LARGE UPPER LEVEL RIDGE CENTERED NEAR 38N40W.
SATELLITE IMAGERY CONTINUES TO SHOW A LARGE AREA OF SAHARAN DUST
THAT EXTENDS FROM THE COAST OF AFRICA TO NEAR 55W...WHICH
FURTHER SUPPORTS FAIR WEATHER.

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

$$
WALTON





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