[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201753
TWDAT

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

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 37W/38W S OF 13N MOVING W NEAR 15 KT.
THIS PSN HAS BEEN ADJUSTED A FEW DEGREES TO THE W BASED ON AN
INVERTED-V SHAPE IN THE LOW TO MID LEVEL CLOUDS. LOW-LEVEL
SATELLITE DERIVED WINDS CONFIRM A PRETTY CLEAR ASSOCIATED NE-SE
WIND SHIFT. CONVECTION IS MINIMAL WITH ONLY SCATTERED SHOWERS
AND ISOLATED TSTMS WITHIN 240 NM EITHER SIDE OF THE WAVE AXIS.

A TROPICAL WAVE IS IN THE ERN CARIBBEAN TITLED ALONG 65W/66W S
OF 19N MOVING W NEAR 15 KT. WHILE THE OVERALL STRUCTURE OF THE
WAVE IS NOT PARTICULARLY IMPRESSIVE...THERE STILL IS A FAIR
AMOUNT OF ASSOCIATED MOISTURE. DOPPLER RADAR FROM SAN JUAN
DEPICTS SCATTERED SHOWERS AND TSTMS ACROSS THE COASTAL WATERS.
SIMILAR ACTIVITY IS LIKELY OCCURRING N OF 15N BETWEEN 64W-70W.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 11N14W 9N21W 7N29W 6N41W 5N52W.
SCATTERED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF THE
AXIS BETWEEN 20W-30W. THIS ACTIVITY COULD BE ASSOCIATED WITH THE
LEADING EDGE OF A WEAK TROPICAL WAVE JUST OFF THE COAST OF W
AFRICA. THIS AREA WILL BE MONITORED AND A TROPICAL WAVE MAY BE
ADDED TO THE SFC MAP DURING THE NEXT DAY OR TWO.

...DISCUSSION...

THE GULF OF MEXICO...
MOST OF THE GULF LIES IN A NLY UPPER FLOW REGIME BETWEEN AN
UPPER HIGH CENTERED OVER S MEXICO NEAR 21N100W...A DIGGING UPPER
TROUGH ACROSS THE EASTERN CONUS AND A CUT OFF LOW JUST N OF THE
CENTRAL BAHAMAS. THESE UPPER WINDS ARE ADVECTING DEBRIS HIGH
LEVEL CLOUDINESS INTO THE REGION FROM MESOSCALE CONVECTIVE
COMPLEXES OVER THE S CENTRAL U.S. AND NE MEXICO. AT THE SFC...A
WEAK 1015 MB LOW IS LOCATED OVER THE FL PANHANDLE WITH
ASSOCIATED SFC TROUGHING STRETCHING SW TO 27N86W. DOPPLER RADAR
DEPICTS SCATTERED SHOWERS AND TSTMS OVER N FL WITH A NARROW LINE
OF ACTIVITY EXTENDING INTO THE COASTAL WATERS ALONG THE SFC
TROUGH. 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. LOOKING AHEAD...NWP MODELS SHOW THE WEAK LOW
OR TROUGH MOVING VERY SLOWLY TO THE E. THIS WILL ALLOW THE SFC
FLOW TO REMAIN LIGHT THRU THE END OF THE WORK WEEK.
THEREAFTER...SFC WINDS AND MOISTURE MAY INCREASE ACROSS THE SRN
WATERS AS THE CARIB TROPICAL WAVE APPROACHES.

THE CARIBBEAN SEA...
A SPRAWLING UPPER HIGH IS CENTERED JUST E OF THE LESSER ANTILLES
NEAR 14N56W WITH RIDGING STRETCHING W TO 75W. ANOTHER UPPER
HIGH...CENTERED OVER S MEXICO...HAS RIDGING THAT STRETCHES E
ALONG 20N TO 84W. THE ACTIVE WEATHER LIES IN THE WEAKNESS
BETWEEN THESE RIDGES...INDUCED BY TROUGHING N OF THE REGION.
UPPER DIFFLUENCE...MID-LEVEL ENERGY AND CONVERGENCE ASSOCIATED
WITH THE ITCZ ARE LIKELY ALL FACTORS THAT HAVE IGNITED AND
MAINTAINED LARGE CLUSTERS OF NUMEROUS MODERATE/SCATTERED STRONG
CONVECTION IN THE SW CARIB S OF 12N BETWEEN 77W-82W. AN EXTENDED
SATELLITE LOOP INDICATES THAT THIS CONVECTIVE ACTIVITY FORMED
AROUND 00Z OVER NW COLOMBIA. SINCE THEN...THIS LARGE CLUSTER HAS
EXPANDED AND BEEN TRACKING RATHER QUICKLY WWD. SHALLOWER
SCATTERED SHOWERS AND TSTMS...ASSOCIATED WITH A TROPICAL WAVE
ALONG 65W/66W...IS AFFECTING A GOOD PORTION OF THE NE CARIB N OF
16N BETWEEN 64W-70W. FOR MORE DETAILS REFER TO THE TROPICAL
WAVES SECTION ABOVE. 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.

THE ATLANTIC OCEAN...
AN UPPER LOW IS SPINNING N OF THE CENTRAL BAHAMAS NEAR 27N74W.
THIS LOW HAS 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.
SCATTERED SHOWERS ARE AHEAD OF THIS FRONT TRIGGERED BY A
PRE-FRONTAL TROUGH ANALYZED FROM 31N47W 26N64W. ANOTHER WEAK
INACTIVE TROUGH LIES FURTHER E ALONG 37W FROM 23N-30N.
OTHERWISE...A SFC HIGH PRES RIDGE IS IN CONTROL RUNNING FROM A
1024 MB HIGH S OF THE AZORES NEAR 35N26W TO A 1022 MB CENTER
NEAR 25N46W TO A 1021 MB CENTER NEAR 28N69W. THIS NARROW RATHER
LOW-LATITUDE 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 THE E AND MOST OF THE TROPICAL ATLC.

$$
CANGIALOSI




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