[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191038
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED SEP 19 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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 FEATURE...
A WEAK SURFACE LOW PRESSURE AREA AND A UPPER-LEVEL LOW NEAR THE
FLORIDA PENINSULA ARE PRODUCING A LARGE AREA OF DISTURBED
WEATHER OVER THE WESTERN ATLANTIC...NORTHERN BAHAMAS...AND THE
EAST COAST OF FLORIDA. THERE ARE NO SIGNS OF ORGANIZATION AT
THIS TIME. HOWEVER...SURFACE PRESSURES ARE SLOWLY FALLING AND
ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR A SUBTROPICAL OR A
TROPICAL CYCLONE TO FORM OVER THE NEXT DAY OR TWO...AS THE
DISTURBANCE MOVES WESTWARD OVER FLORIDA AND INTO THE GULF OF
MEXICO. REGARDLESS OF DEVELOPMENT...THIS SYSTEM WILL LIKELY
BRING SHOWERS...SQUALLS...AND LOCALLY HEAVY RAINS OVER PORTION
OF FLORIDA DURING THE NEXT DAY OR TWO. MOSAIC DOPPLER RADAR FROM
THE SE US SHOWS SCATTERED TO NUMEROUS SHOWERS WITH EMBEDDED
TSTMS ROTATING CYCLONICALLY MAINLY OVER NORTH-CENTRAL FLORIDA.
SCATTERED SHOWERS ARE ALONG SOUTH FLORIDA EAST COAST.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 29W S OF 16N MOVING W 10-15 KT. THE WAVE
HAS AN INVERTED-V PATTERN ON SATELLITE IMAGERY. SCATTERED
MODERATE CONVECTION IS FROM 10N-12N BETWEEN 25W-31W.

TROPICAL WAVE IS ALONG 52W/53W S OF 21N MOVING W NEAR 15 KT.
SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS FEATURE
HAVE DIMINISHED. UPPER-LEVEL WINDS ARE UNFAVORABLE FOR
DEVELOPMENT OF THIS SYSTEM. A CLUSTER OF MODERATE CONVECTION IS
WITHIN 200 NM EAST OF THE WAVE AXIS FROM 18N-20N BETWEEN 46W-49W.

TROPICAL WAVE IS ALONG 84W/85W S OF 20W MOVING W 10-15 KT.
SHOWER ACTIVITY REMAINS LIMITED IN ASSOCIATION WITH THIS WAVE.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N15W 11N25W 6N35W 7N50W 7N62W.
SCATTERED MODERATE CONVECTION IS INLAND OVER W AFRICA MOVING W
ALONG THE IMMEDIATE COASTAL WATERS WITHIN 200 NM N OF THE ITCZ
AXIS. THIS ACTIVITY MAY BE ASSOCIATED WITH A NEW TROPICAL WAVE.
SCATTERED MODERATE CONVECTION IS FROM 4N-9N BETWEEN 31W-36W.

DISCUSSION...

GULF OF MEXICO...
A CLOSED UPPER-LEVEL LOW IS CENTERED ALONG THE W COAST OF
FLORIDA NEAR TAMPA COVERING THE EASTERN GULF AND THE STATE OF
FLORIDA. A MID/UPPER LEVEL TROUGH EXTENDS ACROSS THE EASTERN US
TO THIS LOW. DRY AIR WRAPPING AROUND THE LOW DOMINATES MOST OF
THE EASTERN GULF...WESTERN CUBA AND SOUTH FLORIDA. A 1009 MB SFC
LOW CURRENTLY LOCATED ENE OF MIAMI NEAR 26N79W IS INTERACTING
WITH THIS UPPER LOW. THE SFC LOW IS EXPECTED TO MOVE W INTO GULF
OF MEXICO TODAY. THIS LOW PRES AREA MAY DEVELOP INTO A
SUBTROPICAL OR TROPICAL CYCLONE. FOR MORE DETAILS SEE SPECIAL
FEATURE. AN UPPER RIDGE EXTENDS ACROSS THE W-CENTRAL GULF FROM
THE YUCATAN PENINSULA TO THE COAST NEAR THE LOUISIANA/TEXAS
BORDER. ANOTHER UPPER LOW IS INLAND OVER MEXICO NEAR 23N99W
SPREADING MOISTURE THROUGH SOUTH-CENTRAL MEXICO...THE BAY OF
CAMPECHE AND THE SW GULF. UPPER DIFFLUENCE BETWEEN THIS UPPER
LOW AND A RIDGE OVER THE YUCATAN PENINSULA/NORTHERN CENTRAL
AMERICA IS HELPING TO INDUCE A LINE OF SHOWERS WITH ISOLATED
TSTMS OVER THE SW GULF AND THE BAY OF CAMPECHE. SFC RIDGING
DOMINATES THE SE US AND THE NORTHERN GULF WATERS PRODUCING
MODERATE NE TO E WINDS OF 15 TO 20 KT N OF 26N. AN EARLIER
QUIKSCAT PASS CONFIRMED THESE WINDS...STRONGEST OVER THE NE
CORNER OF THE GULF WHERE PRES GRADIENT TIGHTENS.

CARIBBEAN SEA...
A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE CARIBBEAN SEA. AN
UPPER RIDGE ANCHORED ON A HIGH OVER NICARAGUA COVERS THE NW
CARIBBEAN ENHANCING SHOWER ACTIVITY OVER CENTRAL AMERICA. A WEAK
SURFACE TROUGH IS BENEATH THIS UPPER RIDGE EXTENDING ALONG THE
YUCATAN PENINSULA/NORTHERN GUATEMALA GENERATING SCATTERED
SHOWERS AND ISOLATED TSTMS INLAND. A SECOND UPPER HIGH IS IN THE
SE CARIBBEAN NEAR 12N62W COVERING THE REMAINDER OF THE REGION.
IN BETWEEN...THERE IS AN UPPER TROUGH THAT EXTENDS ACROSS THE
CENTRAL CARIBBEAN FROM HISPANIOLA TO W PANAMA. MODERATE TO
STRONG CONVECTION HAS FLARED UP NEAR THE COLOMBIA/PANAMA BORDER
THANKS TO A DIFFLUENT PATTERN ALOFT AND THE PRESENCE OF THE EPAC
ITCZ. A SURFACE TROUGH EXTENDS FROM THE REMNANTS OF INGRID IN
THE NE CARIBBEAN GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS OVER THE NORTHERN LEEWARD ISLANDS.

ATLANTIC OCEAN...
A WEAK SURFACE LOW PRESSURE AREA AND AN UPPER-LEVEL LOW NEAR THE
FLORIDA PENINSULA ARE PRODUCING A LARGE AREA OF DISTURBED WEATHER
OVER THE WESTERN ATLANTIC...PORTIONS OF THE BAHAMAS...AND
PORTIONS OF THE FLORIDA PENINSULA. THIS REMAINS THE MAIN FEATURE
OF INTEREST IN THE ATLANTIC. REFER TO SPECIAL FEATURE FOR MORE
DETAILS. THE UPPER LOW ALONG THE W COAST OF FLORIDA EXTENDS
ACROSS THE FLORIDA PENINSULA AND THE W ATLC TO 75W. A WEAK UPPER
HIGH IS TO THE E NEAR 30N65W. AN UPPER TROUGH ENTERS THE AREA
NEAR 31N53W EXTENDING SW TO 20N66W. THERE ARE TWO UPPER LOWS
EMBEDDED IN THIS TROUGH. ONE IS NEAR 25N63W...THE SECOND ONE IS
NEAR 31N53W. A SURFACE TROUGH RELATED TO THIS UPPER TROUGH
EXTENDS FROM 30N50W TO NEAR 25N60W. LOW TO MID CLOUDS WITH
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE JUST E AND WITHIN
150 NM OF THE SURFACE TROUGH. THE REMNANT CIRCULATION OF INGRID
IS ANALYZED AS A 1011 MB SURFACE LOW NEAR 21N64W WITH A SURFACE
TROUGH EXTENDING ALONG 63W/64W S OF 24N INTO THE NE CARIBBEAN.
UPPER DIFFLUENCE ASSOCIATED WITH THE AFOREMENTIONED UPPER TROUGH
IS SUPPORTING A LARGE CLUSTER OF MODERATE TO ISOLATED STRONG
CONVECTION JUST EAST OF INGRID'S REMNANTS. AN UPPER RIDGE
GENERALLY ALONG 15N COVERS THE TROPICAL ATLC. N OF THE RIDGE
UPPER WLY FLOW DOMINATES THE REMAINDER OF THE FORECAST AREA E OF
40W.

$$
GR




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