[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 220002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUL 21 2008

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM DOLLY AT 22/0000 UTC IS CENTERED NEAR 23.1N 91.8W
OR ABOUT 330 NM EAST OF LA CRUZ MEXICO AND ABOUT 350 NM
EAST-SOUTHEAST OF BROWNSVILLE TEXAS MOVING WNW AT 16 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED
WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. PLEASE SEE THE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24
KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/ WTNT34 KNHC FOR
MORE DETAILS. VISIBLE SATELLITE IMAGERY CLEARLY SHOWS THE CLOSED
CENTER OF CIRCULATION AND LARGE AREAL EXTENT OF THE STORM WITH
DEEP CONVECTION INCREASING IN THE NORTHWESTERN QUADRANT WITHIN
175 NM OF THE CENTER. ANOTHER AREA OF SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS ACROSS THE YUCATAN CHANNEL FROM
19N-24N BETWEEN 84W-88W. NUMEROUS MODERATE SHOWERS REMAIN WITHIN
350 NM OF THE CENTER AS A LARGE UPPER ANTICYCLONE COVERS THE
ENTIRE GULF OF MEXICO PROVIDING DOLLY WITH SUFFICIENT OUTFLOW
ALOFT. DOLLY IS EXPECTED TO INCREASE IN STRENGTH OVER THE NEXT
24-48 HOURS AS SEA SURFACE TEMPERATURES ACROSS THE GULF REMAIN
HIGH AND THE UPPER LEVEL REGIME CONTINUES TO REMAIN CONDUCIVE
FOR DEVELOPMENT.

TROPICAL STORM CRISTOBAL AT 21/2100 UTC IS CENTERED NEAR 37.1N
71.4W OR ABOUT ABOUT 230 NM EAST-NORTHEAST OF CAPE HATTERAS
NORTH CAROLINA AND ABOUT 570 NM SOUTHWEST OF HALIFAX NOVA SCOTIA
MOVING NE AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000
MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT.
PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT3/WTNT23 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT3/ WTNT33 KNHC FOR MORE DETAILS. SOME FURTHER
INTENSIFICATION IS POSSIBLE FOR CRISTOBAL WHILE THE CENTER MOVES
ACROSS THE GULF STREAM AND THE UPPER LEVEL SHEAR REMAINS LOW
DURING THE NEXT 24 HOURS OR SO. THEREAFTER IT IS EXPECTED THAT
CRISTOBAL WILL MOVE OVER THE COOLER WATERS NORTH OF THE GULF
STREAM AND COME UNDER INCREASED SHEAR VALUES...THEN BECOMING
EXTRATROPICAL AND EMBEDDED WITHIN THE HIGH-LATITUDE WESTERIES.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 120
NM OF THE CENTER IN THE EASTERN SEMICIRCLE.

...TROPICAL WAVES...

STRONG TROPICAL WAVE HAS BEEN ADDED TO THE 21/1800 UTC SURFACE
ANALYSIS AND IS ALONG 17W S OF 20N MOVING W NEAR 15-20 KT. A
1007 MB LOW IS ANALYZED ALONG THE AXIS NEAR 17N. WAVE EXHIBITS A
GOOD DEAL OF BROAD CYCLONIC TURNING AS IT IS EMERGING OFF AFRICA
AND INTO THE OPEN WATERS OF THE ERN ATLANTIC. NO ORGANIZED DEEP
CONVECTION IS NORTH OF THE ANALYZED LOW WITH ONLY SCATTERED
SHOWERS WITHIN 150 NM ON EITHER SIDE OF THE AXIS N OF 16N.
SCATTERED MODERATE CONVECTION IS FROM 9N-16N BETWEEN 15W-19W AND
REMAINS LARGELY EMBEDDED WITHIN THE ITCZ.

TROPICAL WAVE IS ALONG 47W/48W S OF 14N MOVING W NEAR 20 KT.
WAVE REMAINS LOW AMPLITUDE WITH A WEAK MID LEVEL ROTATION
EMBEDDED WITHIN THE ITCZ NEAR 7N. THIS WAVE IS LOCATED WITHIN
AN AREA OF DRY STABLE AIR THUS NO ASSOCIATED SHOWERS/CONVECTION.

TROPICAL WAVE IN THE CENTRAL CARIBBEAN IS ALONG 71W S OF 19N
MOVING W 15-20 KT. WAVE IS EMBEDDED WITHIN DRY STABLE AIR AND
LAST FEW VISIBLE SATELLITE IMAGES INDICATE A VERY WEAK CLOUD
SIGNATURE. ISOLATED SHOWERS ARE ACROSS FAR NRN VENEZUELA AND
WITHIN 60 NM OF THE COAST...INCLUDING THE ABC ISLANDS. SCATTERED
MODERATE CONVECTION REMAINS INLAND ACROSS NRN VENEZUELA FROM
7N-10N BETWEEN 65W-72W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N17W 8N28W 10N36W 9N46W 9N50W
8N59W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS
WITHIN 120 NM ON EITHER SIDE OF THE AXIS BETWEEN 22W-32W.
CLUSTERS OF WIDELY SCATTERED MODERATE CONVECTION IS FROM 5N-8N
BETWEEN 32W-36W.

...DISCUSSION...

GULF OF MEXICO...
THE MAIN CONCERN FOR THE GULF OF MEXICO IS T.S. DOLLY AS IT
MOVES AWAY FROM THE N YUCATAN COAST AND INTO THE WEST CENTRAL
GULF...SEE SPECIAL FEATURES ABOVE. BROAD UPPER LEVEL OUTFLOW
COVERS MOST OF THE GULF S OF 29N. WEAK UPPER TROUGH EXTENDS FROM
SOUTH CAROLINA AND THE GEORGIA COAST TO ALONG THE E COAST OF
FLORIDA PROVIDING DRIER AIR TO THE FLORIDA PENINSULA. AT THE
SURFACE A WEAK RIDGE OF HIGH PRESSURE COVERS THE SE U.S. WITH A
1018 MB HIGH IN THE NE GULF CENTERED NEAR 29N85W. A SMALL UPPER
LOW IS ACROSS SRN MEXICO AND EXTENDS INTO THE BAY OF CAMPECHE
GENERATING ISOLATED SHOWERS/THUNDERSTORMS ACROSS NRN GUATEMALA
AND SRN PORTIONS OF THE YUCATAN PENINSULA. AREAS OF ISOLATED
SHOWERS/THUNDERSTORMS ARE ACROSS FLORIDA THIS EVENING N OF 27N
AND WILL CONTINUE TO WEAKEN DUE TO PASSING OF PEAK DAYTIME
HEATING.

CARIBBEAN SEA...
T.S. DOLLY IS STILL PRODUCING AN AREA OF SCATTERED SHOWERS AND
THUNDERSTORMS OVER THE FAR NW CARIBBEAN N OF 18N W OF 84W ACROSS
THE YUCATAN CHANNEL AND OVER THE NE TIP OF THE YUCATAN
PENINSULA. SEE SPECIAL FEATURES ABOVE. CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE REMAINDER OF THE NW
CARIBBEAN N OF 15N W OF 84W AND ACROSS HONDURAS AND NRN
NICARAGUA. BROAD UPPER LEVEL OUTFLOW COVERS THE WRN CARIBBEAN W
OF 77W. AN UPPER TROUGH COVERS THE REMAINDER OF THE CARIBBEAN
EXTENDING FROM AN UPPER LOW OFFSHORE OF NRN COLOMBIA NEAR 12N74W
NE TO OVER PUERTO RICO. THIS IS DRAWING DRIER UPPER AIR FROM THE
W ATLC OVER THE CENTRAL AND ERN CARIBBEAN. WITH LITTLE MOISTURE
AT THE SURFACE...THE CARIBBEAN E OF 78W IS CLEAR THIS EVENING
WITH FAIR WEATHER AND 15-25 KT TRADE WINDS. AN UPPER LEVEL
ANTICYCLONIC CIRCULATION IS NEAR 12N55W AND EXTENDS S-SE UPPER
FLOW OVER THE LESSER ANTILLES.

ATLANTIC OCEAN...
T.S. CRISTOBAL IS MOVING NE AWAY FROM THE U.S. EASTERN SEABOARD
WITH SKIES CLEARING ALONG THE COAST. SEE SPECIAL FEATURES ABOVE.
WEAK UPPER TROUGH EXTENDS FROM SOUTH CAROLINA AND THE GEORGIA
COAST TO ALONG THE E COAST OF FLORIDA BRINGING DRIER AIR TO THE
FLORIDA PENINSULA AND THE FAR W ATLC. A SECOND WEAK UPPER LOW IS
NEAR 27N74W AND IS DRAWING UPPER LEVEL MOISTURE FROM T.S.
CRISTOBAL SOUTH OVER THE BAHAMAS BETWEEN 74W-78W BUT IS NOT
PRODUCING ANY SHOWER ACTIVITY. A COMPLEX UPPER LOW/TROUGH COVERS
THE REMAINDER OF THE WRN ATLC AND EXTENDS INTO THE CENTRAL ATLC
BETWEEN 55W-70W WITH A 1016 MB SURFACE LOW CENTERED NEAR 31N64W
AND ASSOCIATED SURFACE TROUGH EXTENDING SW TO 27N68W. THIS IS
GENERATING SCATTERED SHOWERS WITHIN 90 NM ON EITHER SIDE OF THE
TROUGH. AN UPPER RIDGE IS OVER THE REMAINDER OF THE CENTRAL ATLC
ANCHORED EAST OF THE LESSER ANTILLES NEAR 12N55W AND EXTENDS
NORTHWARD ALONG 55W TO 26N. THIS RIDGE IS PROVIDING UPPER LEVEL
DIFFLUENCE TO THE E OF THE SURFACE TROUGH GENERATING SCATTERED
SHOWERS FROM 24N-29N BETWEEN 55W-60W. A LARGE SURFACE RIDGE OF
HIGH PRESSURE DOMINATES THE ATLC E OF 60W.

$$
HUFFMAN




This weather bulletin was brought to you by:
www.nashvilleweather.net