[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 142330
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT APR 14 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N12W 3N20W 2N30W 1N40W EQ50W.
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF THE AXIS
BETWEEN 21W-26W. SCATTERED MODERATE TO STRONG IS FROM THE EQ-4N
BETWEEN 6W-10W.

...DISCUSSION...

THE GULF OF MEXICO...
A STRONG COLD FRONT (FOR THIS TIME OF YEAR) IS PRESSING SE
ACROSS THE GULF. AS OF 21Z...THE FRONT WAS ANALYZED FROM SE
LOUISIANA TO VERACRUZ MEXICO ALONG 30N91W 25N93W 19N96W THEN
STALLED ALONG THE SIERRA MADRE MOUNTAINS IN MEXICO TO 21N99W.
IT'S NOT MUCH OF A CHALLENGE TO FIND THIS FRONT AS THERE IS AN
IMPRESSIVE WIND SHIFT WITH SHIPS/BUOYS REPORTING SLY WINDS OF
15-20 KT E OF THE FRONT AND NWLY WINDS IN THE 20-30 KT RANGE
BEHIND IT. TEMP/DWPT GRAD IS ALSO IMPRESSIVE...NOT SURPRISING
GIVEN THE WIND STRUCTURE...WITH UPPER 70'S E OF THE FRONT TO
TEMPS FALLING THROUGH THE 60'S AND DWPTS THRU THE 50'S IN THE NW
GULF. DOPPLER RADAR SHOWS SCATTERED SHOWERS AND TSTMS WITHIN 120
NM AHEAD OF THE FRONT OVER MUCH OF THE COASTAL WATERS. IR IMAGES
AND LIGHTNING DATA SUGGEST THAT SIMILAR ACTIVITY EXISTS OUT OF
RADAR RANGE N OF 26N ROUGHLY WITHIN 90 NM AHEAD OF THE FRONT. IN
THE UPPER LEVELS...THE TROUGH (SUPPORT FOR THE FRONT) IS STILL
OVER THE CENTRAL U.S. WITH MUCH OF THE GULF LYING ON THE N AND
NW PERIPHERY OF A STRONG UPPER HIGH IN THE CARIB. THIS IS
PROVIDING SW-WLY UPPER FLOW AND BROKEN STREAKS OF HIGH CLOUDS
ACROSS THE REGION.

LOOKING AHEAD...THE COLD FRONT IS EXPECTED TO CONTINUE ITS SE
PUSH CLEARING THE ENTIRE AREA TOMORROW EVENING BRINGING IN A
COOLER AND DRIER AIRMASS ADVECTED BY STRONG NWLY WINDS.
HOWEVER...BEFORE IT CROSSES SHOWERS AND TSTMS...SOME POSSIBLY
STRONG TO SEVERE...ARE POSSIBLE AS LOW-LEVEL CONVERGENCE ALONG
THE BNDRY IS EXPECTED TO BE STRONG WITH SUFFICIENT FORCING ALOFT.

THE CARIBBEAN SEA...
A STRONG MID TO UPPER LEVEL HIGH IS CENTERED MIDWAY BETWEEN
JAMAICA AND HONDURAS NEAR 17N81W. EXTENSIVE SE TO SLY UPPER
LEVEL FLOW ON THE SW AND W PERIPHERY OF THE HIGH IS SPREADING
DEBRIS CLOUDS AND ISOLATED SHOWERS FROM THE MODERATE CONVECTION
IN THE ITCZ. MUCH OF THIS CLOUD COVER IS OVER CENTRAL AMERICA.
ABUNDANT DRY SUBSIDENT FLOW DOMINATES THE REGION ALONG AND TO
THE E OF THE RIDGE AXIS...81W...SUPPRESSING THE FORMATION OF ANY
DEEP CLOUDINESS OR TSTM ACTIVITY. AT THE SFC...WEAK HIGH PRES IS
LOCATED WELL N OF THE AREA OFF THE CAROLINA COASTLINE. THIS HIGH
IS MAINTAINING MODERATE ELY TRADES EVERYWHERE...EXCEPT THE NW
CARIB WHERE THE SFC WINDS HAVE SHIFTED TO THE SE IN RESPONSE TO
THE STRONG COLD FRONT IN THE GULF OF MEXICO. THESE TRADES ARE
STEERING PATCHES OF LOW-LEVEL CLOUDS AND EMBEDDED ISOLATED
SHOWERS OVER THE LESSER ANTILLES...PUERTO RICO AND HISPANIOLA. S
AND W OF THERE...THE LOW-LEVEL CLOUD STREAMERS ARE VERY THIN AND
LIKELY ONLY CONTAIN BRIEF LIGHT SHOWERS. A WEATHER CHANGE IS IN
STORE FOR THE AREA OVER THE NEXT FEW DAYS...ASSOCIATED WITH THE
STRONG COLD FRONT CURRENTLY IN THE GULF. NWP MODELS SHOW THIS
FRONT ENTERING THE NW PORTION IN 18-24 HOURS AND ONLY SLOWLY
WEAKENING AS IT MOVES ACROSS THE AREA OVER THE NEXT FEW DAYS.

THE ATLANTIC OCEAN...
RATHER WEAK PRES PATTERN EXISTS ACROSS THE ATLC BASIN. A 1020 MB
HIGH IS SINKING SE NOW CENTERED NEAR 33N74W PROVIDING SFC
RIDGING ACROSS THE WRN ATLC. TROUGHING COVERS A GOOD PORTION OF
THE CENTRAL ATLC WITH SEVERAL WEAK FRONTAL AND REMNANT
BOUNDARIES. STARTING FROM W TO E...A WEAK 1010 MB LOW IS LOCATED
AT THE BASE OF A COLD FRONT NEAR 28N50W WITH A SFC TROUGH
HANGING SWD TO 26N55W. ANOTHER WEAK TROUGH LIES JUST AHEAD OF
THE LOW FROM 30N47W TO 22N58W. VERY LIMITED MOISTURE IS
ASSOCIATED WITH ANY OF THESE SYSTEMS. FARTHER E...A COLD FRONT
ENTERS THE AREA NEAR 32N22W TO 26N29W THEN SWINGS BACK TO THE N
AS A WARM FRONT TO 32N41W. THERE IS A LITTLE MORE MOISTURE
ASSOCIATED WITH THIS SYSTEM IN A WEAK UPPER DIFFLUENT ZONE N OF
27N BETWEEN 37W-44W. A 1019 MB HIGH CENTERED TO THE S AND E OF
THE WEAK FRONTS NEAR 23N35W CONTROLS THE PATTERN ACROSS THE
TROPICAL ATLC PRODUCING MAINLY LIGHT TO MODERATE TRADES. THE
UPPER LEVEL PATTERN IS ALSO NOT VERY AMPLIFIED WITH NWLY
FLOW...ON THE E SIDE OF THE CARIB HIGH...COVERING THE AREA W OF
60W. UPPER CONFLUENCE TO THE W OF THE TROUGH AXIS ASSOCIATED
WITH THE FRONTS IN THE CENTRAL ATLC IS STABILIZING THE AIR N OF
25N BETWEEN 47W-67W. SIMILAR STORY ASSOCIATED WITH THE ERN ATLC
COLD FRONT/TROUGH N OF 25N BETWEEN 15W-25W. ELSEWHERE THE FLOW
IS FAIRLY ZONAL WITH PATCHES OF HIGH LEVEL CLOUDS.

$$
CANGIALOSI





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