[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 300556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU JUN 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURE...

T.S. ARLENE IS CENTERED NEAR 21.6N 97.0W AT 30/0600 UTC OR ABOUT
60 NM SE OF TAMPICO MEXICO MOVING W AT 8 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 996 MB. MAXIMUM SUSTAINED WIND SPEED IS 50
KT WITH GUSTS TO 60 KT. PLEASE SEE THE LATEST NHC INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC
AND THE FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. NUMEROUS STRONG
CONVECTION IS ALONG A 200 NM WIDE SWATH FROM THE STORM CENTER SE
TO GUATEMALA NEAR 14N90W. NUMEROUS MODERATE/SCATTERED STRONG
CONVECTION IS ALSO FROM 15N-21N BETWEEN 95W-103W ACROSS SRN
MEXICO...FROM 21N-25N BETWEEN 97W-99W...AND FROM 23N-26N BETWEEN
92W-96W.

...TROPICAL WAVES...

A TROPICAL WAVE IS IN THE WRN TROPICAL ATLC ALONG 53W FROM
8N-15N MOVING W NEAR 20 KT. THE WAVE REMAINS IN AN AREA OF
ENHANCED MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY.
AN ASCAT SCATTEROMETER PASS FROM 0126 UTC SHOWS BROAD LOW LEVEL
CYCLONIC FLOW IS AROUND THE WAVE AXIS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS MAINLY W OF THE WAVE AXIS
FROM 10N-14N BETWEEN 52W-60W. SOME OF THIS ACTIVITY IS
INFLUENCED BY MOIST SWLY FLOW ALOFT AROUND AN UPPER LEVEL RIDGE
OVER THE WAVE.

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN S OF ERN CUBA ALONG
75W FROM 13N-19N MOVING W NEAR 10 KT. THE WAVE IS E OF AN AREA
OF MODERATE MOISTURE VALUES THAT HAVE MOVED ACROSS THE WRN
CARIBBEAN. THIS WAVE LOST MOST OF ITS ENERGY AFTER INTERACTING
WITH AN UPPER LEVEL LOW NOW DIRECTLY OVER THE WAVE. THE UPPER
LEVEL LOW IS DRAWING DRY AIR ALOFT INTO THE CENTRAL CARIBBEAN
WHICH IS INHIBITING ANY DEEP CONVECTION NEAR THE WAVE AXIS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA FROM THE PRIME MERIDIAN
AT 23N ALONG 19N8W 19N17W 10N26W. THE ITCZ CONTINUES FROM 10N26W
ALONG 10N35W 7N45W 8N55W 7N59W. ISOLATED MODERATE/STRONG
CONVECTION IS WITHIN 150 NM S OF THE AXIS BETWEEN
23W-33W...WITHIN 200 NM S BETWEEN 33W-45W...AND WITHIN 100 NM N
OF THE AXIS BETWEEN 35W-40W.

...DISCUSSION...

GULF OF MEXICO...
TROPICAL STORM ARLENE CONTINUES TO IMPACT MUCH OF THE SW GULF OF
MEXICO. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. HIGH LEVELS
OF MOISTURE ARE ACROSS THE MAJORITY OF THE BASIN. SCATTERED
SHOWERS/THUNDERSTORMS ARE NOTED OVER THE SE GULF N OF WRN CUBA
FROM 23N-24N BETWEEN 82W-85W. ISOLATED SHOWERS/POSSIBLE
THUNDERSTORMS ARE OVER THE REMAINDER OF THE SE GULF. ALOFT...
ANTI-CYCLONIC OUTFLOW FROM ARLENE IS COVERING MUCH OF THE WRN
GULF. AN UPPER RIDGE AXIS ALSO EXTENDS FROM SRN LOUISIANA ACROSS
FLORIDA AND INTO THE WRN ATLC. AN UPPER LEVEL TROUGH IS SINKING
SWD OVER THE ERN CONUS AND IS JUST N OF THE NE GULF. THIS UPPER
TROUGH SUPPORTS A SURFACE TROUGH EXTENDING ACROSS THE FLORIDA
PANHANDLE FROM 31N84W TO 30N88W. SCATTERED SHOWERS/THUNDERSTORMS
WITH SOME STRONG ARE E OF THE TROUGH N OF 28N BETWEEN 81W-84W. A
WEAK SURFACE RIDGE IS OVER THE N CENTRAL GULF AROUND A 1016 MB
HIGH NEAR 28N89W. MODERATE DRY AIR ALOFT IS OVER THE SURFACE
RIDGE. THIS COMBINATION IS PROVIDING MOSTLY FAIR CONDITIONS OVER
THE NRN GULF N OF 27N W OF 85W...BESIDES A FEW WIDELY ISOLATED
SHOWERS OVER SE LOUISIANA. EVEN THOUGH ARLENE WILL BE INLAND
WITHIN 24 HOURS...SIGNIFICANT MOISTURE WILL REMAIN OVER THE SW
GULF OF MEXICO. THE UPPER TROUGH OVER THE ERN CONUS WILL ALSO
LIKELY CAUSE SHOWERS/THUNDERSTORMS OVER THE NE GULF WHILE WEAK
SURFACE RIDGING WILL REMAIN OVER THE NRN GULF.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH COVERS THE MAJORITY OF THE WRN AND CENTRAL
CARIBBEAN CENTERED AROUND AN UPPER LEVEL LOW NEAR 16N74W. WHILE
THE LOW IS WRAPPING DRY AIR CLOSEST TO ITS CENTER KEEPING MUCH
OF THE CENTRAL CARIBBEAN DRY AND CLEAR...A FEW ISOLATED SHOWERS
ARE OVER THE WRN...AND ERN CARIBBEAN. A TROPICAL WAVE IS S OF
ERN CUBA ALONG 75W...BUT DO TO THE AFOREMENTIONED DRY AIR ALOFT
IT IS NOT CAUSING MUCH ACTIVE WEATHER. A FEW STRONGER SHOWERS
MAY MOVE INTO THE SRN WINDWARD ISLANDS AS SOME HIGHER MOISTURE
VALUES AHEAD OF A TROPICAL WAVE MOVE INTO THE ERN CARIBBEAN.
THIS AREA IS ALSO UNDER MOIST SLY FLOW ALOFT BETWEEN THE UPPER
TROUGH OVER THE WRN AND CENTRAL CARIBBEAN AND AN UPPER LEVEL
RIDGE COVERING THE ERN PORTION E OF 68W. 20 KT ELY TRADEWINDS
COVER THE MAJORITY OF THE BASIN. EXPECT THE TROPICAL WAVE IN THE
CENTRAL CARIBBEAN TO CONTINUE TO MOVE WWD WITH POSSIBLE
SHOWERS...AS ACTIVITY INCREASES IN THE ERN CARIBBEAN AS ANOTHER
TROPICAL WAVE APPROACHES THE LESSER ANTILLES.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH OVER THE ERN CONUS IS PUSHING SE
SUPPORTING A FEW ISOLATED SHOWERS/THUNDERSTORMS OFF THE ERN
SEABOARD. AN AREA OF SCATTERED SHOWERS/THUNDERSTORMS ARE OVER
THE NW BAHAMAS FROM 24N-28N BETWEEN 77W-80W. THE REMAINDER OF
THE BASIN IS DOMINATED BY BROAD SURFACE RIDGING EXTENDING FROM A
1033 MB HIGH NE OF THE AZORES ISLANDS NEAR 46W17N WITH AXIS
EXTENDING ALONG 35N31W 29N55W AND TO THE FLORIDA STRAITS. THE
RIDGE IS MAINTAINING MOSTLY FAIR CONDITIONS BASINWIDE.
ALOFT...AN UPPER LEVEL RIDGE EXTENDS ACROSS FLORIDA INTO THE SW
ATLC TO NEAR 32N71W. AN UPPER LEVEL LOW IS SPINNING NEAR 28N51W
SUPPORTING A FEW ISOLATED SHOWERS/THUNDERSTORMS FROM 29N-31N
BETWEEN 56W-60W. BROAD UPPER RIDGING COVERS MUCH OF THE TROPICAL
ATLC AROUND A CENTER NEAR 13N52W AND 12N29W. AN UPPER LEVEL
TROUGH COVERS THE FAR E ATLC WITH AXIS JUST W OF THE CANARY
ISLANDS. EXPECT SHOWER ACTIVITY TO CONTINUE OVER THE FAR WRN
ATLC WITH SURFACE RIDGING REMAINING.

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

$$
WALTON






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