[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUN 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 40W S OF 13N MOVING W NEAR 15 KT.
SATELLITE IMAGERY SHOWS AN INVERTED-V SHAPE IN THE LOW TO MID
LEVEL CLOUDS ASSOCIATED WITH THE WAVE. CURRENTLY CONVECTION IS
MINIMAL AND MAINLY WITHIN THE ITCZ. THIS TROPICAL WAVE IS
FORECAST TO MOVE ACROSS THE WINDWARD ISLANDS DURING THE UPCOMING
WEEKEND.

A TROPICAL WAVE IS IN THE ERN CARIBBEAN TITLED ALONG 67W/68W S
OF 20N MOVING W NEAR 15 KT. THIS WAVE BEGAN TO AFFECT THE U.S.
VIRGIN ISLANDS THIS MORNING AND AFTERWARD PUERTO RICO. THE SAN
JUAN DOPPLER RADAR DETECTED AREAS OF HEAVY RAINFALL OVER THE
INTERIOR AND NW PORTIONS OF PUERTO RICO WITH THE PASSAGE OF THE
WAVE. MOISTURE ASSOCIATED WITH THE WAVE WILL CONTINUE TO SPREAD
OVER DOMINICAN REPUBLIC/HAITI TONIGHT AND REACH E CUBA AND
JAMAICA THU MORNING.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 11N15W 7N25W 6N38W 5N45W 4N54W.
SCATTERED MODERATE CONVECTION IS WITHIN 70-90 NM EITHER SIDE OF
THE AXIS BETWEEN 30W-38W. CLUSTERS OF MODERATE CONVECTION ARE
FROM 6N-12N BETWEEN 10W-15W. SIMILAR CONVECTION IS NOTED OVER
FRENCH GUIANA AND GUYANA. CLOUDS MOTION SUGGESTS A LOW/MID
CYCLONIC CIRCULATION ALONG THE ITCZ NEAR 25W. THE 18Z RUN OF THE
GFS MODEL ALSO SHOWS A VORTICITY MAXIMUM AT MID LEVEL. THESE
CLOUDS MAY BE ASSOCIATED WITH A NEW TROPICAL WAVE.

...DISCUSSION...

THE GULF OF MEXICO...
NLY UPPER LEVEL WINDS DOMINATES MOST OF THE GULF ASSOCIATED WITH
AN UPPER HIGH THAT REMAINS CENTERED OVER CENTRAL MEXICO. AN
UPPER TROUGH IS DIGGING ACROSS THE EASTERN CONUS AND A CUT OFF
LOW JUST IS N OF THE CENTRAL BAHAMAS. THESE UPPER WINDS ARE
ADVECTING UPPER LEVEL MOISTURE INTO THE WESTERN GULF. AS OF
21Z...A 1012 MB LOW IS LOCATED OVER NORTHERN FLORIDA WITH A
TROUGH EXTENDING SW TO 27N89W. DOPPLER RADAR DEPICTS SCATTERED
SHOWERS AND TSTMS OVER N-CENTRAL FL ASSOCIATED WITH THE LOW.
MODEST HIGH PRES RIDGING IS BUILDING SE W OF THE LOW. THIS
OVERALL WEAK PRES PATTERN IS PROVIDING THE AREA WITH LIGHT WINDS
AND LOW SEAS. THE GFS MODEL SHOWS THE WEAK LOW MOVING SLOWLY
INTO THE NE CORNER OF THE GULF THU TO FRI. SFC WINDS AND
MOISTURE MAY INCREASE ACROSS THE SRN WATERS AS THE CARIB
TROPICAL WAVE APPROACHES SAT.

THE CARIBBEAN SEA...
AN UPPER HIGH IS CENTERED JUST E OF THE LESSER ANTILLES NEAR
14N57W WITH RIDGING STRETCHING W TO 80W. SWLY WINDS ON THE
WESTERN SIDE OF THIS UPPER HIGH ARE TRANSPORTING UPPER LEVEL
MOISTURE/HIGH CLOUDS FROM NORTHERN SOUTH AMERICA/CENTRAL AMERICA
INTO THE E-CENTRAL CARIBBEAN. ANOTHER UPPER HIGH...LOCATED OVER
CENTRAL MEXICO IS PRODUCING NLY FLOW OVER THE YUCATAN
PENINSULA...NORTHERN CENTRAL AMERICA AND THE EXTREME NW
CARIBBEAN. IN BETWEEN THESE RIDGES...AN UPPER TROUGH EXTENDS
FROM CENTRAL CUBA TO HONDURAS TRIGGERING SOME CONVECTIVE
ACTIVITY OVER CUBA. AT THE SURFACE...A BROAD AREA OF LOW
PRESSURE COUPLE WITH THE ITCZ AND UPPER DIFFLUENCE IS GENERATING
CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION OVER THE SW
CARIBBEAN...SOUTHERN NICARAGUA...COSTA RICA AND WESTERN PANAMA.
THIS CONVECTIVE ACTIVITY IS MOVING WWD. TRADE WINDS ARE ON THE
STRONG SIDE...20 TO 30 KT...IN THE CENTRAL CARIB. THESE STRONG
WINDS ARE EXPECTED TO PERSIST AND EXPAND OVER THE NEXT COUPLE
DAYS. A TROPICAL WAVE IS MOVING ACROSS THE E CARIBBEAN. SEE
TROPICAL WAVES SECTION.

THE ATLANTIC OCEAN...
AN UPPER LOW IS SPINNING N OF THE CENTRAL BAHAMAS NEAR 27N74W.
THIS LOW IS DEEPENING THE LARGE SCALE UPPER TROUGHING ASSOCIATED
WITH AN OCCLUDED LOW PRES SYSTEM IN THE N ATLC. A SLOW MOVING
DRY FRONTAL BOUNDARY CLIPS THE NRN PORTION OF THE AREA RUNNING
E-W ALONG 31N/32N BETWEEN 50W AND BERMUDA. A PRE-FRONTAL TROUGH
IS ANALYZED FROM 31N45W TO 25N61W. SCATTERED SHOWERS ARE WITHIN
80 NM AHEAD OF THIS TROUGH. ANOTHER WEAK TROUGH LIES FURTHER E
ALONG 30N37W 20N44W. OTHERWISE...A SFC HIGH PRES RIDGE IS IN
CONTROL OF THE FORECAST AREA RUNNING FROM A 1027 MB HIGH S OF
THE AZORES NEAR 36N24W TO A 1022 MB CENTER NEAR 24N47W TO A 1021
MB CENTER NEAR 28N68W. THIS NARROW RIDGE IS ALLOWING WINDS TO BE
LIGHT TO MODERATE ACROSS MOST OF THE ATLC DISCUSSION AREA. THE
COMBINATION OF THIS HIGH PRES ALONG WITH DRY STABLE AIR ALOFT
ASSOCIATED WITH AN UPPER RIDGE CENTERED NEAR 17N23W IS PROVIDING
TRANQUIL CONDITIONS ACROSS MOST OF THE TROPICAL ATLC.

$$
GR





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