[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 301728
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED MAY 30 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS LOCATED ALONG 32W S OF 9N MOVING W ABOUT 15
KT. THERE IS A HINT OF LOW TO MID LEVEL SIGNATURE ASSOCIATED
WITH THIS WEAK LOW-LATITUDE FEATURE THAT MOVED OFF THE AFRICAN
COAST ABOUT 3 DAYS AGO. THEREFORE...THE PSN IS BASED MOSTLY ON
THIS CLOUD STRUCTURE WHICH MATCHED UP WELL WITH CONTINUITY.
CONVECTION IS FAIRLY LINEAR AND APPEARS MAINLY ASSOCIATED WITH
THE ITCZ.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N11W 4N22W 4N30W 5N35W 5N52W.
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM N OF THE AXIS
BETWEEN 19W-27W...34W-41W...AND W OF 46W. SIMILAR ACTIVITY IS
WITHIN 120 NM S OF THE AXIS E OF 14W.

...DISCUSSION...

THE GULF OF MEXICO...
PRONOUNCED UPPER TROUGHING COVERS THE MAJORITY OF THE GULF
EXTENDING SWD FROM THE ROCKIES TOWARD THE YUCATAN PENINSULA. THE
COMBINATION OF UPPER DIFFLUENCE TO THE E OF THE TROUGH AXIS AND
LOW TO MID LEVEL CONVERGENCE NEAR A LOW LEVEL TROUGH BOUNDARY
ALONG 87W S OF 23N IS FUELING SCATTERED TO NUMEROUS SHOWERS AND
TSTMS S OF 25N BETWEEN 83W-88W. IR IMAGES AND LIGHTNING DATA
SUGGEST THAT THE ASSOCIATED MORE ACTIVE WEATHER IS IN THE NW
CARIB. RELATIVELY QUIET CONDITIONS...PATCHY MID-HIGH LEVEL
CLOUDS...EXIST ELSEWHERE. AT THE SFC...A 1023 MB HIGH PRES IS
CENTERED OVER NE GEORGIA. THE TIGHTENED PRES GRADIENT BETWEEN
THE HIGH AND TROUGH NEAR THE YUCATAN CHANNEL IS PICKING UP ELY
WINDS TO 20-25 KT IN THE FL STRAITS AND 15-20 KT ELSEWHERE IN
THE E GULF. THESE WINDS LIGHTEN AND VEER TO THE S/SE IN THE W
GULF ON THE W PERIPHERY OF THE RIDGE. LOOKING AHEAD A DAY OR
TWO...THE MAIN FEATURE OF INTEREST IS THE LOW-LEVEL TROUGH
MENTIONED. SEVERAL COMPUTER MODELS SHOW THIS FEATURE MOVING NE
INCREASING WINDS AND PULLING TROPICAL MOISTURE ACROSS THE E GULF.

THE CARIBBEAN SEA...
SCATTERED SHOWERS AND TSTMS PERSIST ACROSS THE W CARIB NAMELY W
OF 81W...WITH THE GREATEST AREA OF CONVECTION APPROACHING THE
WRN TIP OF CUBA FROM THE SW. THIS MOISTURE IS ASSOCIATED WITH A
LOW-LEVEL TROUGH WHICH RUNS FROM NICARAGUA TO THE YUCATAN
CHANNEL CONTINUING INTO THE SE GULF. VIS IMAGES DISPLAY A BROAD
ENVELOPE OF CYCLONIC TURNING IN THE LOW LEVELS...ALTHOUGH QSCAT
AND SFC OBS LIKELY INDICATE THAT THE MORE SUBSTANTIAL AMPLITUDE
IS OFF THE SFC. ASSOCIATED ISOLATED TSTMS EXTEND FURTHER E
BETWEEN 74W AND 81W MAINLY S OF JAMAICA. FARTHER E...THE TAIL
END OF AN ATLC SFC TROUGH EXTENDS JUST N OF HISPANIOLA. UPPER
DIFFLUENCE TO THE E OF THIS BOUNDARY IS SUPPORTING SCATTERED
SHOWERS AND ISOLATED TSTMS S OF PUERTO RICO AND ACROSS THE
VIRGIN ISLANDS AS DEPICTED ON DOPPLER RADAR FROM SAN JUAN. A
WEDGE OF DRY STABLE AIR ALOFT EXTENDS ACROSS THE WINDWARD
ISLANDS TO NEAR 15N71W PROVIDING FAIR WEATHER FOR THE SE PORTION
OF THE CARIB SEA. LOOKING AHEAD...COMPUTER MODELS SUGGEST THAT A
FAIR AMOUNT OF MOISTURE WILL REMAIN IN THE W CARIB OVER THE NEXT
FEW DAYS AS THE TROUGH SLOWLY PUSHES NE.

THE ATLANTIC OCEAN...
A DEEP LAYER TROUGH COVERS MUCH OF THE W ATLC EXTENDING FROM
BERMUDA TO THE SE BAHAMAS. PLENTY OF DRY AIR ALOFT COVERS THE
REGION N OF 23N W OF 62W KEEPING THE REGION WITH ONLY SCATTERED
LOW-LEVEL STRATOCUMULUS CLOUDS. THIS UPPER TROUGH IS PROVIDING
SUPPORT FOR TWO SFC BOUNDARIES. ONE IS ANALYZED AS A
TROUGH...LACKING THERMAL STRUCTURE...EXTENDING ALONG 32N58W
22N64W TOWARD HISPANIOLA. LIFT ALONG AND E OF THE BOUNDARY ALONG
WITH DIFFLUENCE ALOFT IS PRODUCING SCATTERED SHOWERS AND TSTMS
BETWEEN 53W-63W. THE OTHER SFC FEATURE IS A BACK DOOR TYPE COLD
FRONT WHICH IS ANALYZED FROM BERMUDA TO THE CAROLINAS. THIS
FEATURE IS MARKED BY THIN LOW CLOUDS AND A SURGE IN THE NLY
FLOW. THE REMAINDER OF THE REGION IS DOMINATED BY A 1027 MB HIGH
NEAR 33N31W. THIS HIGH PRES SYSTEM IS SUPPLYING FAIR WEATHER AND
MODERATE TRADES ACROSS THE TROPICS. IN THE MID AND UPPER
LEVELS...AN ELONGATED TROUGH/RIDGE PATTERN HAS SET UP BUT
OVERALL LITTLE WEATHER IS BEING PRODUCED BY THESE UPPER FEATURES.

$$
JC




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