[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI JAN 18 2008

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 6N10W 3N21W 1N30W EQ40W 1S52W.
WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 50 NM EITHER SIDE
OF AXIS BETWEEN 16W-24W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE NEAR 2N41W AND WITHIN 80 NM N OF AXIS BETWEEN
46W-50W.

...DISCUSSION...

GULF OF MEXICO...
A GALE CENTER IS TAKING SHAPE OVER THE SW CORNER OF THE GULF. AS
A RESULT...A GALE WARNING HAS BEEN ISSUED. AS OF 1500 UTC...A
1012 MB SFC LOW WAS ANALYZED NEAR 21N94W. A STATIONARY FRONT
EXTENDS FROM THE LOW NEWD TO SOUTH-CENTRAL FLORIDA NEAR LAKE
OKEECHOBEE. SATELLITE IMAGERY REVEALS THAT CLOUDS AND CONVECTION
ARE ON THE INCREASE OVER THE WESTERN HALF OF THE GULF...WITH
LIGHTNING DATA SHOWING SCATTERED TSTMS...MAINLY NE OF THE LOW
CENTER. ANOTHER AREA OF SHOWERS IS OVER THE SE PORTION OF THE
GULF NEAR 25N85W ASSOCIATED WITH THE FRONTAL BOUNDARY...WHILE
LOW LEVEL CLOUDS WITH EMBEDDED LIGHT RAIN IS SEEN ALONG THE
MEXICAN GULF COAST JUST EAST OF THE SIERRA MADRE MOUNTAINS. A
SFC TROUGH ALSO EXTENDS NWD FROM THE LOW CENTER TO NEAR 28N95W.
A QUIKSCAT PASS FROM AROUND 12Z INDICATED MODERATE TO STRONG ELY
WINDS OVER MOST OF THE WESTERN GULF...LIGHTER OVER THE REMAINDER
OF THE AREA. ALOFT...A LONGWAVE TROUGH OVER THE CENTRAL CONUS IS
SUPPORTING THE DEVELOPING OF THIS GALE CENTER...WHILE THE UPPER
LEVEL FLOW REMAINS FROM THE SW OVER THE GULF. THE AFOREMENTIONED
FRONTAL BOUNDARY SHOULD BEGIN RETURNING AS A WARM FRONT IN
RESPONSE TO THE NEW CYCLOGENESIS PREVIOUSLY MENTIONED. BY
TONIGHT THE FRONT WILL EXTEND FROM CENTRAL FLORIDA TO A 1012 MB
GALE CENTER NEAR 27N89W AND CONTINUE SW TO NEAR TAMPICO MEXICO.
BY SATURDAY AFTERNOON THE LOW WILL MOVE OVER NE FLORIDA WITH A
TRAILING COLD FRONT EXTENDING SW TO THE BAY OF CAMPECHE. THE
FRONT WILL MOVE ACROSS THE SOUTH FLORIDA AND THE YUCATAN
PENINSULA EARLY SUNDAY. IN THE WAKE OF THE FRONT...EXPECT STRONG
NLY WINDS AND BUILDING SEAS AS HIGH PRES INVADES THE GULF.

CARIBBEAN SEA...
A STRONG MID-TO UPPER-LEVEL RIDGE...ANCHORED ON A HIGH OVER
COLOMBIA CONTINUES TO DOMINATE THE WEATHER PATTERN ACROSS THE
BASIN. THE RIDGE AXIS EXTENDS NWD ALONG 75W TO BEYOND THE
BAHAMAS. STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS IS NOTED
WITHIN THE RIDGE AXIS COVERING THE ENTIRE AREA...INCLUDING ALSO
CENTRAL AMERICA AND NORTHERN COLOMBIA AND VENEZUELA. DESPITE
THIS...A MODERATELY STRONG TRADE WIND FLOW CONTINUES TO PRODUCE
SCATTERED BANDS OF SHOWERS FROM PORTIONS OF THE LESSER ANTILLES
TO THE GULF OF HONDURAS. THE SHOWERS ARE MORE CONCENTRATED OVER
THE NE CARIBBEAN AFFECTING THE UK/US VIRGIN ISLANDS AND PUERTO
RICO. IN FACT...THE SAN JUAN DOPPLER RADAR SHOWS SCATTERED TO
NUMEROUS SHOWERS MOVING WWD ACROSS THOSE ISLANDS AND REGIONAL
COASTAL WATERS. ADDITIONAL CONCENTRATED BANDS OF SHOWERS ARE
ALSO OBSERVED IN THE WEST-CENTRAL CARIBBEAN...LIKELY RELATED TO
THE SHEAR OF THE LOW-LEVEL WIND/SPEED CONVERGENCE. STRONG TRADES
ARE BLOWING ACROSS THE CENTRAL CARIBBEAN WITH AN EARLIER
QUIKSCAT PASS SHOWING 20 TO 30 KT JUST OFFSHORE THE COLOMBIAN
COAST. A STRONG COLD FRONT IS EXPECTED TO MOVE INTO THE NW
CARIBBEAN SAT NIGHT ACCOMPANIED BY STRONG N WINDS AND BUILDING
SEAS.

ATLANTIC OCEAN...
A COLD FRONT IS OVER THE FAR NW PORTION OF THE FORECAST REGION
CROSSING SOUTH-CENTRAL FLORIDA AND THE SE QUADRANT OF THE GULF
OF MEXICO. ANOTHER COLD FRONT ENTERS THE DISCUSSION AREA NEAR
32N37 THEN CONTINUES SW ACROSS THE OCEAN TO NEAR 21N58W. A BAND
OF BROKEN TO OVERCAST LOW CLOUDS AND A FEW SHOWERS ARE WITHIN
90NM EITHER SIDE OF THIS FRONT. SCATTERED MODERATE CONVECTION
LIES WITHIN 200 NM E OF THE FRONT FROM 26N TO BEYOND 32N.
BETWEEN FRONTS...A 1029 MB SFC HIGH CENTERED WELL N OF AREA
DOMINATES. IN THE ERN ATL...A 1036 MB LOCATED OVER PORTUGAL
EXTENDS A RIDGE SW TO 25N35W. AT UPPER LEVELS...A BROAD LONGWAVE
TROUGH LIES EAST OF THE CARIBBEAN HIGH CENTER...COVERING MUCH OF
THE CNTRL AND ERN ATL. AROUND THE BASE OF THE TROUGH...A STRONG
70-90KT JET IS TRANSPORTING CONSIDERABLE UPPER-LEVEL MOISTURE/
HIGH CLOUDS FROM NORTHERN SOUTH AMERICA ALL THE WAY NE TO THE
WEST COAST OF AFRICA...PASSING THROUGH THE CAPE VERDE ISLANDS.

$$
GR




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