[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 222359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN 22 AUG 2004

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...
E ATLC TROPICAL WAVE IS ALONG 22W S OF 20N MOVING W 10 KT.
BROAD AREA OF LOW TO MIDDLE LEVEL ROTATION IS NOTED IN SATELLITE
IMAGERY.  ELY SHEAR IS KEEPING MOST OF THE TSTMS WELL W OF THE
WAVE WITH SCATTERED MODERATE FROM 7N-10.5N BETWEEN 24W-29W.

TROPICAL WAVE ABOUT MIDWAY BETWEEN AFRICA AND THE LESSER
ANTILLES IS ALONG 38W/39W S OF 20N MOVING W 10-15 KT.  THIS IS A
POORLY-DEFINED WAVE WITH A BROAD AREA OF LIGHT WINDS NEAR THE
AXIS.  SURGE OF SAHARAN DUST IS NOTED E OF THE WAVE E OF 30W.
WAVE SHOULD INCREASE RAIN CHANCES FOR THE LEEWARD ISLANDS THU.

CARIBBEAN TROPICAL WAVE IS ALONG 78W/79W S OF 19N MOVING W 20
KT.  WAVE HAS WEAKENED SINCE YESTERDAY WITH ONLY ISOLATED
MODERATE S OF 15N W OF 79W.

TROPICAL WAVE ALONG 94W IS NO LONGER IN THE DISCUSSION AREA.

...ITCZ...
ITCZ AXIS IS ALONG 13N16W 10N27W 10N40W 7N48W 9N52W 10N61W.
ISOLATED WEAK/MODERATE WITHIN 60 NM OF AXIS BETWEEN 45W-55W

...DISCUSSION...
GULF OF MEXICO...
STAGNANT PATTERN OVER THE REGION WITH DEEP-LAYERED HIGH PRESSURE
OVER THE CENTRAL GULF AND TSTMS FORMING OVER ADJACENT LAND AREA
IN THE SOUTHERN USA.  MODERATE SUBSIDENCE IS KEEPING THE GULF
WATERS RATHER QUIET WITH SOME ISOLATED SHOWERS S OF 26N E OF
87W.  SHORTWAVE SEEN IN WATER VAPOR PICTURES IN NE MISSISSIPPI
IS DROPPING SE AND WILL LIKELY INCREASE RAIN CHANCES FOR NE
FLORIDA TOMORROW.  UPPER LOW OVER THE YUCATAN NEAR MERIDA IS
ALLOWING DIURNAL TSTM DEVELOPMENT OVER THE PENINSULA.

CARIBBEAN SEA...
WESTERLY UPPER FLOW IS OVER THE N CARIBBEAN N OF 14N W OF 75W
DUE TO AN UPPER LOW OVER THE BAHAMAS NUDGING INTO THE AREA AND A
HIGH OVER THE SW CARIBBEAN BUILDING NORTHWARD.  WLY SHEAR IS
ENHANCING A FEW SHOWERS N OF 15N W OF 80W CLOSE TO A TROPICAL
WAVE.. OTHERWISE THE WEATHER IS MOSTLY DRY OVER WATER DUE TO
MODERATE/STRONG SUBSIDENCE ALOFT.  UPPER HIGH NEAR 12N79W IS
PROVIDING AN UNSTABLE ENVIRONMENT FOR DAILY TSTM DEVELOPMENT
NEAR THE ITCZ IN THE SW CARIBBEAN OTHERWISE RELATIVELY DRY NW
FLOW IS ON THE NE SIDE OF THE HIGH WITH DECREASING MOISTURE FROM
W TO E FROM THE CENTRAL CARIBBEAN E TO THE LESSER ANTILLES.

SUBTROPICAL ATLANTIC OCEAN...
STATIONARY NARROW TROUGH IS OVER THE NW BAHAMAS ASSISTING
ISOLATED SHOWERS FROM 22N-29N BETWEEN 71W-80W.  WEAK RIDGING IS
OVER THE SE BAHAMAS BUT THE MAIN STORY IS THE RETURN OF A STRONG
MID-OCEANIC TROUGH IN THE CENTRAL ATLC.  TROUGH AXIS RUNS FROM
UPPER LOW NEAR 31N52W SSW TO 15N58W.  INSTABILITY ALOFT IS
ALLOWING A FEW SHOWERS TO FORM FROM 20N-28N BETWEEN 54W-64W
DESPITE TONS OF DRY MID/UPPER LEVEL AIR.  TROUGH AXIS IS QUITE
DEEP WITH A SURFACE TROUGH ALONG 18N54W TO 29N51W.  ISOLATED
SHOWERS N OF 27N BETWEEN 50W-56W.  THE REMNANTS OF DANIELLE ARE
A 1015 MB LOW NEAR 30N41W WITH ISOLATED MODERATE WITHIN 90 NM OF
THE CENTER.  OTHERWISE AT THE SURFACE 1020 MB HIGH NEAR 26N68W
RIDGES W INTO CENTRAL FLORIDA BUT A NOTICEABLE ABSENCE OF TRADES
IS PRESENT IN THE W AND CENTRAL ATLC WITH MOST WINDS LESS THAN
15 KT.  FARTHER E... RIDGING IS BUILDING ALONG 45W WITH A
MID/UPPER LOW NEAR 22N36W ENHANCING A FEW SHOWERS WITHIN 90 NM
OF 25N32W.  OTHERWISE HIGH PRESSURE IS IN THE CONTROL IN THE E
ATLC WITH MID/UPPER ANTICYCLONE NEAR 25N25W.

TROPICAL ATLANTIC...
SIMILAR TO YESTERDAY... TROUGHING ALONG 36W N OF 14N DIVIDES THE
ATLC INTO A MOIST E ATLC AND RATHER DRY W ATLC.  TRADES ARE VERY
LIGHT IN THE DEEP TROPICS WITH AN EARLIER QUIKSCAT PASS SHOWING
10 KT OR LESS OVER THE AREA BETWEEN 30W TO 55W.  MID-OCEANIC
TROUGH HAS SNUCK INTO THE NW PART OF THE AREA WITH UNFAVORABLE
CONDITIONS FOR TROPICAL CYCLONE FORMATION N OF 14N W OF 50W.
RIDGING IS BUILDING BACK INTO THE E ATLC WITH A BIT MORE
MOISTURE ESPECIALLY IN THE ITCZ.

$$
BLAKE



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