[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 230522
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI FEB 23 2007

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N12W 4N21W 2S34W 4S40W. ISOLATED
SHOWERS/TSTMS WITHIN 75 NM OF THE AXIS BETWEEN 15W-28W.
SCATTERED MODERATE CONVECTION S OF 2N W OF 34W SPREADING ACROSS
PORTIONS OF FAR NE BRAZIL...FRENCH GUIANA...AND SURINAME.

...DISCUSSION...

GULF OF MEXICO...

FAIR WEATHER EXISTS UNDER STRONG SFC HIGH PRES ANCHORED WELL N
IN CENTRAL CANADA. A 1022 MB HIGH EMBEDDED IN THE RIDGE HAS BEEN
NEARLY STATIONARY OVER THE PAST 24 HOURS NEAR 29N91W. A WEAK
COLD FRONT CUTS THRU THE RIDGE EXTENDING FROM NEAR JAX ACROSS
THE NE GULF WATERS TO SRN MS. THE FRONT IS DIFFICULT TO TRACK ON
SATELLITE IMAGERY AS THERE IS LITTLE OR NO CLOUDS/MOISTURE
ASSOCIATED WITH IT. SLIGHTLY LOWER PRESSURES AND A SLIGHT WIND
SHIFT DEFINE THE BOUNDARY. ELSEWHERE A WEAK SURFACE TROUGH OVER
THE ERN BAY OF CAMPECHE IS CAUSING AN E/W ORIENTED BAND OF
LOW/MID-LEVEL CLOUDS FROM 23N-26N BETWEEN 89W-95W. IN THE MID
AND UPPER LEVELS...RIDGING IS ALSO THE THEME EXTENDING N FROM
CENTRAL AMERICA WITH A SUBTROPICAL JET BRANCH RIDING ALONG THE
NRN PERIPHERY ADVECTING A CONSIDERABLE AMOUNT OF UPPER MOISTURE
ACROSS NRN MEXICO AND INTO THE N GULF...CURRENTLY CONFINED N OF
27N W OF 90W. THE TAIL END OF UPPER TROUGHING LIES OFF THE U.S.
EAST COAST PROVIDING THE UPPER SUPPORT FOR THE AFOREMENTIONED
COLD FRONT. OTHERWISE THE AREA IS UNDER A SUBSIDENT ENVIRONMENT
WITH LITTLE CLOUD COVER.

THE WEAK COLD FRONT IS EXPECTED TO BECOME NEARLY STATIONARY AND
INCREASINGLY DIFFUSE FROM SOUTH FLORIDA TO NEW ORLEANS FRI
AFTERNOON. A SECOND STRONGER COLD FRONT WILL MOVE OFF THE TEXAS
COAST SAT AFTERNOON PRECEDED BY SCATTERED SHOWERS/TSTMS N OF 27N
ALONG THE GULF COAST...BUT IT TOO WILL STALL OVER THE NRN GULF
WATERS LATE SUN.

CARIBBEAN...

HIGH PRES ACROSS THE GULF OF MEXICO AND W ATLC IS PRODUCING
MODERATE TO FRESH TRADES...EXCEPT STRONGER OFF THE COAST OF
COLOMBIA. THE LARGE-SCALE ENVIRONMENT IS DOMINATED BY A
STRETCHED E/W MID-LEVEL RIDGE ALIGNED ALONG 15N PROVIDING AN
ABUNDANCE OF MODERATE/STRONG SUBSIDENCE ACROSS THE ENTIRE AREA.
THE MOST STABLE CONDITIONS LIE FROM WRN COLOMBIA TO EL SALVADOR
WHERE WV ENHANCEMENTS ARE SHOWING UP IN THE DRIEST RANGE. THIS
IS DUE TO UPPER LEVEL CONFLUENCE BETWEEN THE RIDGE AND A 500 MB
LOW CENTERED OVER VENEZUELA NEAR 7N66W. BENEATH THE STRONG MID
LEVEL CAP...A FEW SMALL PATCHES OF LOW LEVEL MOISTURE ARE BEING
STIRRED UP AND DRIVEN BY THE TRADES...PARTICULARLY ACROSS THE
ISLANDS OF PUERTO RICO AND HISPANIOLA WHERE THERE IS LIKELY SOME
LAND INFLUENCE AND POSSIBLY SOME ENHANCEMENT FROM A WEAK TROUGH
IN THE ATLC.

NO MAJOR PATTERN CHANGES APPEAR TO BE IN STORE FOR THE
AREA OVER THE NEXT DAY OR TWO SO SIMILAR TRADES AND WEATHER
CONDITIONS ARE ANTICIPATED.

WEST ATLANTIC...

GENTLE TROUGHING LIES ACROSS THE MAJORITY OF THE REGION ON THE S
SIDE OF A LARGE POLAR VORTEX. TWO SHORTWAVE TROUGHS ARE EMBEDDED
AND ROTATING IN THE BROAD CYCLONIC FLOW. ONE OF THESE JUST
CLIPS THE AREA WITH ITS BASE NEAR 31N78W PROVIDING SUPPORT FOR
THE WEAK COLD FRONT MENTIONED IN THE GULF SECTION. THE OTHER IS
BETTER DEFINED STRETCHING FROM 32N54W TO NEAR 24N67W. BEHIND
THIS QUICK MOVING AXIS...SUBSIDENCE IS ENHANCED AND WIDESPREAD
PROVIDING STABLE CONDITIONS ALOFT. A RELATED ILL-DEFINED SFC
TROUGH RUNS FROM 30N59W ACROSS THE CENTRAL BAHAMAS. ANOTHER SFC
TROUGH...REMNANTS OF A RATHER LONG LIVED FRONTAL BOUNDARY...IS
ALONG 26N52W 20N64W. NEITHER OF THESE BOUNDARIES ARE PRODUCING
MUCH WEATHER AND MAINLY DEFINED BY WIND SHIFTS AS DEPICTED BY A
QSCAT PASS NEAR 23Z.

THE WEAK SFC BOUNDARIES ARE EXPECTED TO PUSH E WITH THE UPPER
SUPPORT AS HIGH PRES BUILDS OVER THE WEN PORTION OF THE REGION
ON SAT.

EAST ATLANTIC...

SFC HIGH PRES IS THE RULE ANCHORED BY A 1029 MB ABOUT 250-300 NM
WNW OF THE CANARY ISLANDS. THIS HIGH IS PROVIDING MODERATE TO
STRONG TRADES ACROSS A GOOD PORTION OF THE AREA. ALOFT...THE
FLOW HAS FLATTENED AND IS NOW BASICALLY ZONAL ACROSS MOST OF THE
SUBTROPICAL AREAS. IN THE TROPICS...THE PATTERN IS A LITTLE MORE
COMPLEX WITH AN EXTENSIVE BROAD FLAT RIDGE STRETCHED ACROSS THE
EQUATORIAL ATLC. A CUT OFF UPPER LOW NEAR THE CAPE VERDE ISLANDS
IS ERODING THE N SIDE OF THE RIDGE ADVECTING SOME PATCHY HIGH
CLOUDS FROM 14N-23N BETWEEN 23W-29W.

OVER THE NEXT COUPLE OF DAYS...NWP MODELS LITTLE CHANGE AT THE
SFC BUT AN AMPLIFICATION IN THE UPPER PATTERN AS A LARGE
RIDGE DEVELOPS IN RESPONSE TO A DEEPENING TROUGH IN THE NW ATLC.

$$
CANGIALOSI




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