[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222336
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI DEC 22 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N8W 4N20W 2N30W 5N43W 5N53W.
SCATTERED MODERATE TO STRONG CONVECTION WITHIN 180 NM EITHER
SIDE BETWEEN 12W AND 27W. SCATTERED MODERATE CONVECTION WITHIN
120 NM N OF AXIS W OF 42W.

...DISCUSSION...
GULF OF MEXICO...
MOST STRIKING FEATURE OVER THE GULF WATERS THIS AFTERNOON IS A
WELL DEVELOPED LINE OF SHOWERS AND THUNDERSTORMS OVER THE
EASTERN GULF...FROM CEDAR KEY TO THE SOUTH CENTRAL GULF NEAR
23N86W. THIS LINE IS WELL DEFINED BY FRESH TO STRONG SE FLOW
OVER THE EASTERN GULF AROUND THE PERIPHERY OF BOUNDARY LAYER
RIDGE CENTERED OVER THE WESTERN ATLC...CONVERGING WITH S TO SW
FLOW OVER THE CENTRAL GULF. IN ADDITION...SUBTROPICAL JET IS
ACTIVE FROM TAMPICO MEXICO TO THE CENTRAL FLORIDA
PANHANDLE...SUPPLYING ABUNDANT MID AND UPPER LEVEL MOISTURE WITH
VISIBLE SATELLITE IMAGERY SHOWING OVERCAST MULTILAYER DECKS OVER
MOST OF THE WESTERN GULF N OF BAY OF CAMPECHE. FURTHER E...UPPER
WINDS VEER MORE WLY OVER TOP OF UPPER RIDGE AXIS EXTENDING FROM
HONDURAS THROUGH S FLORIDA. THE RESULT IS STRONG ISENTROPIC LIFT
OVER THE LOW LEVEL CONVERGENT BOUNDARY ON W EDGE OF BOUNDARY
LAYER RIDGE...AND A LINE OF NELY TRAINING CELLS TRANSLATING EWD
INTO THE W COAST OF FLORIDA. THE STRONG SUBTROPICAL JET IS AHEAD
OF A STALLED UPPER TROUGH EXTENDING THROUGH NORTHERN MEXICO.
SURFACE FRONT EXTENDS FROM SOUTHERN LOUISIANA TO 1013 MB LOW
PRES CENTERED NEAR 22N95W. THE FRONT HAS BECOME STATIONARY THIS
AFTERNOON AS UPPER FLOW HAS BECOME MORE PARALLEL THE FRONT.
FURTHER W...A STRONGER SHORT WAVE TROUGH IS PUSHING THROUGH THE
SW UNITED STATES CURRENTLY...AND WILL DIG INTO THE BASE OF THE
TROUGH OVER MEXICO THROUGH SAT. AS THIS APPROACHES...THE FRONT
OVER THE WESTERN AND CENTRAL GULF WILL PUSH EWD TONIGHT BEFORE
STALLING AGAIN LATE SAT FROM FLORIDA BIG BEND AREA TO BAY OF
CAMPECHE. MODELS INCLUDING ECMWF AND ENSEMBLE GFS RUNS SHOW A
STRONGER FRONT EMERGING OFF THE TEXAS COAST SAT NIGHT...WITH
CYCLOGENESIS ALONG OVER THE NW GULF SUN AS SUPPORTING UPPER
DYNAMICS SHIFT E THROUGH TEXAS. THE LOW IS PROGGED TO LIFT OUT
INTO THE WESTERN FLORIDA PANHANDLE BY EARLY MON...WITH WINDS TO
GALE FORCE LATE SUN BEHIND THE TRAILING COLD FRONT. STRONG NLY
FLOW WILL GRADUALLY SUBSIDE THROUGH MIDWEEK OVER GULF WATERS AS
HIGH PRES TO THE N SHIFTS E ACROSS THE DEEP SOUTH.

CARIBBEAN SEA...
FRESH ELY WINDS PERSIST ACROSS THE CARIBBEAN BASIN S OF 18N...S
OF BOUNDARY LAYER RIDGE CENTERED TO THE N. SPEED CONVERGENCE
FROM THIS FLOW IS RESULTING IN A LINE OF SHOWERS FROM EASTERN
HONDURAN COAST TO EASTERN PANAMA. OTHERWISE...DRY SUBSIDENT AIR
IN THE MID AND UPPER LEVELS CONTINUES TO PUSH INTO THE WESTERN
CARIBBEAN ON THE W SIDE OF A STATIONARY UPPER TROUGH EXTENDING
FROM HISPANIOLA TO WESTERN PANAMA. ALOFT...40 TO 50 KT SW TO W
FLOW PERSIST OVER THE SOUTH CENTRAL AND EASTERN CARIBBEAN
BETWEEN THE UPPER TROUGH TO THE NW AND AN UPPER RIDGE TO THE SE
OVER THE TROPICAL ATLC. FOR THE WEEKEND...ELY WINDS WILL
INCREASE SLIGHTLY OVER THE CARIBBEAN BASIN AS HIGH PRES BUILDS
TO THE N. FRONTAL BOUNDARY WILL PUSH INTO THE YUCATAN CHANNEL
EARLY NEXT WEEK...AND BRING STRONG NLY WINDS TO EXTREME NW
CARIBBEAN N OF HONDURAS.

ATLANTIC OCEAN...
HIGHLY AMPLIFIED UPPER LEVEL PATTERN CONTINUES OVER THE
SUBTROPICAL ATLC. A BROAD UPPER RIDGE IS EMERGING OFF THE
SOUTHEAST COAST OF THE U.S. N OF AN UPPER TROUGH IN THE CENTRAL
CARIBBEAN. COMPLEX INTERACTION BETWEEN THESE FEATURES IS
RESULTING IN PERSISTENT DIFFLUENT AREA THAT IN TURN CONTINUES TO
ENHANCE SMALL AREA OF MODERATE CONVECTION BETWEEN HISPANIOLA AND
TURKS AND CAICOS ISLANDS. AT THE SURFACE...1031 MB HIGH PRES IS
CENTERED ALONG 31N N OF THE LESSER ANTILLES. MODERATE TO FRESH
TRADES ARE EVIDENT ACROSS THE WATERS S OF THE RIDGE W OF 50W.
FURTHER E...UPPER TROUGH EXTENDS FROM 31N40W TO 16N46W.
AFTERNOON QUIKSCAT PASS PAINTED AN ASSOCIATED STATIONARY FRONT
BENEATH THE UPPER TROUGH EXTENDING FROM 32W37W TO 23N48W.
QUIKSCAT IMAGERY ALSO DEPICTED A PERSISTENT WEAK TROUGH ALONG
31N. E OF THIS...DEEP LAYER RIDGE AND STABLE AIR PERSISTS TO THE
NORTH AFRICAN COAST. OVER THE TROPICAL ATLC S OF 20N...QUIKSCAT
IMAGERY SHOWS FRESH TO STRONG NELY SURFACE FLOW E OF
30W...BENEATH THE STRONGER RIDGING TO THE N. ELSEWHERE...ONLY
MODERATE TO FRESH NE TO E TRADES PERSIST TO THE ANTILLES.
ALOFT...40 TO 50 KT WLY FLOW IS EVIDENT ON N SIDE OF ELONGATED
UPPER RIDGE ALONG 4N. THE ASSOCIATED UPPER DIFFLUENCE ALONG WITH
INCREASING CONVERGENCE ALONG THE ITCZ IS AIDING SCATTERED
CONVECTION AS DESCRIBED ABOVE.

$$
CHRISTENSEN




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