[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271049
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU AUG 27 2009

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...

TROPICAL STORM DANNY IS CENTERED NEAR 27.4N 72.1W AT 27/0900 UTC
OR ABOUT 320 NM ENE OF NASSAU AND ABOUT 500 NM SSE OF CAPE
HATTERAS NORTH CAROLINA MOVING NW AT 9 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 50
KT WITH GUSTS TO 60 KT. SCATTERED MODERATE TO STRONG CONVECTION
IS FROM 26N-29N BETWEEN 67W-72W. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE
DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 24W S OF 20N MOVING W NEAR 15 KT. THIS
WAVE COINCIDES WITH A BROAD AREA OF LOW-LEVEL CYCLONIC CURVATURE
AND CIMSS WAVETRAK GUIDANCE DEPICTS A MAXIMUM AREA OF 850 MB
VORTICITY IN THE VICINITY OF THE WAVE AXIS AND ACROSS THE CAPE
VERDE ISLANDS. AN AREA OF SCATTERED MODERATE TO STRONG
CONVECTION IS SW OF THE WAVE AXIS FROM 7N-13N BETWEEN 25W-31W
AND IS POSSIBLY THE RESULT OF LOCALIZED LOW-LEVEL CONVERGENCE W
OF THE AXIS AND ALONG THE ITCZ AXIS. THIS CONVECTION IS FURTHER
ENHANCED BY UPPER LEVEL DIFFLUENCE ON THE SRN PERIPHERY OF AN
ERN TROPICAL ATLC UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED
NEAR 19N29W.

TROPICAL WAVE IS ALONG 46W S OF 20N MOVING W NEAR 20 KT. THE
WAVE CONTINUES TO MOVE BENEATH AN VERY DRY AIR MASS ALOFT AS AN
UPPER LEVEL RIDGE EXTENDS TO 40W ACROSS THE TROPICAL ATLC.
STRONG SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY...HOWEVER...AN
UPPER LEVEL LOW IS CENTERED N OF THE WAVE AXIS AND IS STRETCHING
AN AREA OF POSSIBLE SHOWERS NWD FROM 19N-24N BETWEEN 43W-50W.
OTHER POSSIBLE SHOWERS ARE MOSTLY EMBEDDED WITHIN THE ITCZ AXIS
FROM 10N-14N BETWEEN 42W-49W.

TROPICAL WAVE IS ALONG 77W S OF 19N MOVING W NEAR 12 KT. WAVE
REMAINS WITHIN AN AREA OF MAXIMUM DEEP LAYER MOISTURE AS
OBSERVED ON THE TOTAL PRECIPITABLE WATER IMAGERY...HOWEVER
DRY...SUBSIDENT NELY FLOW ALOFT IS OVER THE CENTRAL CARIBBEAN
AND THUS INHIBITING ANY DEEP CONVECTION OR SHOWER ACTIVITY.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 15N16W 14N23W 12N27W 12N44W
11N47W 10N63W. WIDELY SCATTERED MODERATE CONVECTION IS ALONG THE
W AFRICA COAST FROM 8N-14N BETWEEN 13W-17W. ASIDE FROM THE AREA
OF CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG 24W...
SCATTERED SHOWERS ARE WITHIN 200 NM EITHER SIDE OF THE AXIS
BETWEEN 37W-56W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH IS ANALYZED ACROSS THE ERN GULF AND EXTENDS
FROM 28N86W TO THE TIP OF THE NW YUCATAN PENINSULA NEAR 22N90W.
THIS SURFACE TROUGH IS SUPPORTED BY AN UPPER LEVEL LOW CENTERED
OVER ERN LOUISIANA. THE SURFACE TROUGH ALONG WITH MIDDLE TO
UPPER LEVEL DIFFLUENCE SE OF THE UPPER LOW IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS MUCH OF THE NE GULF
N OF 25N AND E OF 90W. AN UPPER LEVEL RIDGE COVERS THE REMAINDER
OF THE GULF ANCHORED BY AN UPPER LEVEL ANTICYCLONE CENTERED OVER
THE YUCATAN CHANNEL. BETWEEN THESE TWO UPPER LEVEL FEATURES...
MOIST SWLY FLOW EXTENDS FROM E/CENTRAL MEXICO TO THE NE GULF AND
NRN FLORIDA WITH POSSIBLE SCATTERED SHOWERS WITHIN 90 NM EITHER
SIDE OF A LINE FROM TAMPICO MEXICO THROUGH 24N90W TO THE BIG
BEND REGION OF FLORIDA. A WEAK RIDGE OF HIGH PRESSURE IS
FORECAST TO REMAIN ACROSS THE WRN GULF WATERS AHEAD OF THE NEXT
FRONTAL BOUNDARY THAT IS EXPECTED TO STALL ALONG THE LOUISIANA
AND TEXAS GULF COAST BY EARLY SUNDAY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE IS ACROSS THE NW CARIBBEAN AND NRN PORTIONS
OF CENTRAL AMERICA ANCHORED OVER THE YUCATAN CHANNEL WHILE UPPER
LEVEL TROUGHING COVERS THE CENTRAL CARIBBEAN ANCHORED BY AN
UPPER LOW CENTERED NEAR 15N75W. THE UPPER DIVERGENT FLOW ACROSS
THE FAR WRN CARIBBEAN AND PORTIONS OF CENTRAL AMERICA ARE
GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS OVER CENTRAL
AMERICA...THE GULF OF HONDURAS AND THE YUCATAN PENINSULA.
SIMILAR CONVECTION HAS INCREASED OVER THE PAST 6 HOURS IN THE SW
CARIBBEAN IN CLOSE PROXIMITY TO THE ITCZ AXIS WHICH LIES ACROSS
PANAMA. MOST OF THE ACTIVITY HOWEVER IS REMAINING S OF 10N. THE
REMAINDER OF THE CARIBBEAN IS UNDER DRY STABLE AIR AND MOSTLY
CLEAR SKIES.

ATLANTIC OCEAN...
THE PRIMARY CONCERN FOR THE ATLC IS TROPICAL STORM DANNY LOCATED
OVER PORTIONS OF THE SW NORTH ATLC. THE UPPER LEVEL LOW OVER THE
CENTRAL CARIBBEAN EXTENDS UPPER LEVEL TROUGHING N TO NEAR T.S.
DANNY WHILE UPPER RIDGING IS LOCATED TO THE E AND W OF THE
SYSTEM. THE CONVECTION PRIMARILY ASSOCIATED WITH DANNY IS
LOCATED IN THE NW QUADRANT OF AN UPPER LEVEL ANTICYCLONE
CENTERED NEAR 24N64W. SCATTERED MODERATE TO STRONG CONVECTION IS
FROM 26N-29N BETWEEN 67W-72W. THE REMAINDER OF THE SW NORTH ATLC
IS UNDER NE TO ELY SURFACE FLOW WITH ISOLATED SHOWERS FROM
24N-31N MOVING WWD ACROSS THE BAHAMAS AND INLAND ACROSS THE
FLORIDA PENINSULA. AN UPPER LEVEL LOW IS CENTERED OVER THE
CENTRAL ATLC NEAR 27N48W. UPPER LEVEL DIFFLUENCE LOCATED E OF
THE UPPER LOW AND A SURFACE TROUGH ANALYZED FROM 32N47W TO
26N51W IS GENERATING SCATTERED SHOWERS FROM 25N-33N BETWEEN
44W-50W. FARTHER TO THE EAST...A WEAKENING UPPER LEVEL TROUGH
WITH AXIS N OF 22N ALONG 37W IS PRODUCING POSSIBLE SCATTERED
SHOWERS FROM 22N-32N BETWEEN 31W-35W. ELSEWHERE ACROSS THE
CENTRAL AND ERN ATLC...A SURFACE RIDGE REMAINS IN PLACE AND IS
ANCHORED BY A 1025 MB HIGH CENTERED N OF THE DISCUSSION AREA
NEAR 35N32W.

$$
HUFFMAN



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