[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131728
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 13 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...

TROPICAL WAVE IS ADDED TO THE 12Z ANALYSIS JUST E OF THE CAPE
VERDE ISLANDS ALONG 21W/22W S OF 20N MOVING W NEAR 15 KT.
SATELLITE IMAGES AND SSMI DERIVED TPW PRODUCT SHOWS A VERY BROAD
AREA OF LOW TO MID LEVEL TURNING WITH A HINT OF AN ELONGATED
CIRCULATION NEAR 16N22W. UPPER AIR DATA FROM DAKAR DISPLAYED A
CLEAR WAVE SIGNAL WITH THE PASSAGE OCCURRING JUST BEFORE 00Z. IN
ADDITION...SYNOPTIC SFC OBS IN THE REGION INDICATE 24-H PRES
FALLS NEAR 2 MB. DESPITE THE LARGE STRUCTURE AND WELL-DEFINED
SIGNAL IN THE AFOREMENTIONED DATA...SHOWER ACTIVITY IS MINIMAL
NEAR THE AXIS ITSELF WITH MOST OF IT ALIGNED LINEARLY ALONG THE
ITCZ.

TROPICAL WAVE IS TITLED ALONG 5N46W 22N43W MOVING W 15-20 KT.
SATELLITE IMAGERY SHOWS A PRONOUNCED INVERTED V-SHAPE TITLING
EWD WITH LATITUDE...DECIDED TO INCREASE AMPLIFICATION AND TILT
BASED ON THIS STRUCTURE. CONVECTION IS FAIRLY MINIMAL WITH ONLY
A SMALL PATCH OF SCATTERED MODERATE FROM 12N-14N BETWEEN 43W-46W
...THOUGH SCATTERED SHOWERS ARE LIKELY OCCURRING WITHIN 240 NM
EITHER SIDE OF THE WAVE AXIS. GFS HAS THIS WAVE INITIALIZED WELL
AND SHOWS IT MOVING ACROSS THE LESSER ANTILLES ON SUN BRINGING
AN INCREASE IN MOISTURE.

TROPICAL WAVE IS IN THE CENTRAL CARIB ALONG 76W S OF 17N MOVING
W 15-20 KT. LITTLE SIGNATURE IS SEEN ON SATELLITE IMAGES OR SFC
OBS...THEREFORE THE CURRENT PSN FOLLOWS FORWARD CONTINUITY.

TROPICAL WAVE IS OVER PORTIONS OF CENTRAL AMERICA AND THE NW
CARIB ALONG 86W S OF 20N MOVING W NEAR 15 KT. THIS WAVE IS
CONVECTIVELY ACTIVE WITH SCATTERED MODERATE MOSTLY WITHIN 240 NM
E OF THE WAVE AXIS S OF 17N. THE WAVE ALSO HAS FAIR STRUCTURE
WITH SOME EVIDENCE OF WEAK BANDING.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N15W 8N23W 6N35W 9N43W 11N48W
7N61W. CLUSTERS OF SCATTERED MODERATE CONVECTION IS WITHIN 240
NM S OF THE AXIS E OF 21W AND WITHIN 150 NM EITHER SIDE OF THE
AXIS BETWEEN 21W-29W. SIMILAR CONVECTION IS WITHIN 120 NM EITHER
SIDE BETWEEN 50W-57W.

...DISCUSSION...
GULF OF MEXICO...
VERY WEAK SFC PRES PATTERN...RESULTING IN LIGHT WINDS...
DOMINATES THE GULF THANKS TO A 1018 MB HIGH CENTERED IN THE
MID-GULF NEAR 26N90W. A WEAK SFC TROUGH...AHEAD OF A STALLED
FRONT ACROSS THE DEEP SOUTH...EXTENDS FROM THE FL PANHANDLE TO
THE N CENTRAL GULF ALONG 30N84W 27N89W. LONG RANGE DOPPLER RADAR
SHOWS THE FORMATION OF SHOWERS AND TSTMS WITHIN 75 NM N OF THE
ANALYZED TROUGH AXIS. ELSEWHERE...SKIES ARE MOSTLY FAIR UNDER
THE INFLUENCE OF DRY N-NELY UPPER FLOW ON THE W PERIPHERY OF AN
UPPER RIDGE CENTERED OVER NRN MEXICO. THE WEAK PRES PATTERN IS
ANTICIPATED TO REMAIN IN PLACE THIS WEEKEND ALLOWING WINDS TO BE
OF LITTLE CONCERN. THE GREATEST CHANCE OF RAIN THIS WEEKEND WILL
BE NEAR THE N GULF COAST ASSOCIATED WITH UPPER SHORTWAVES AND IN
THE BAY OF CAMPECHE AS THE NRN BRANCH OF THE TROPICAL WAVE IN
THE W CARIB APPROACHES.

CARIBBEAN SEA...
THE MOST ACTIVE WEATHER IN THE BASIN IS OVER ERN PORTIONS OF
CENTRAL AMERICA AND THE W CARIB ENHANCED BY A NEARBY TROPICAL
WAVE. LATEST IR IMAGES SHOW THE MOST ORGANIZED CONVECTION ALONG
THE ERN COASTS OF NICARAGUA AND HONDURAS AND FURTHER S OVER
COSTA RICA AND THE EXTREME SW CARIB WATERS. OTHERWISE...
CONDITIONS ACROSS THE CARIB ARE FAIRLY QUIET WITH HIGH LEVEL
CLOUDINESS OBSERVED BETWEEN 15-20N DRIVEN BY UPPER WLYS AND
TYPICAL QUICK MOVING TRADE WIND SHOWERS TRAVERSING ACROSS THE
REGION. SPEAKING OF THE TRADES...THIS MORNING'S QSCAT PASS
GENERALLY SHOWED THE ELYS IN THE 20-30 KT RANGE...STRONGEST NEAR
THE COAST OF COLOMBIA. ORGANIZED RAIN CHANCES WILL LIKELY
INCREASE ON SUN ACROSS THE LESSER ANTILLES AS THE NEXT TROPICAL
WAVE NEARS.

ATLANTIC OCEAN...
STRONG SFC RIDGING DOMINATES THE ATLC DISCUSSION AREA ANCHORED
BY A STATIONARY 1029 MB CENTER NEAR 35N49W. A WEAK LOW-LEVEL
TROUGH ALONG 57W/58W FROM 20N-26N IS GENERATING SCATTERED
CLOUDINESS AND ISOLATED SHOWERS WITHIN 60 NM E OF THE AXIS.
FURTHER W...A LINE OF SCATTERED SHOWERS AND TSTMS LIE AHEAD OF
A FRONTAL BOUNDARY ALONG THE SE U.S. COAST GENERALLY N OF 31N
BETWEEN 75W-78W. ALOFT...THE PATTERN IS FAIRLY COMPLEX WITH A
SERIES OF CUT OFF LOWS AND HIGHS. SINCE NONE OF THESE UPPER
SYSTEMS ARE PRODUCING ANY SIGNIFICANT AREAS OF CLOUDINESS/
SHOWERS WILL NOT MENTION THE POSITIONS. WIDESPREAD DRY STABLE
AIR IS THE GENERAL THEME CAPPING THE LOW-LEVEL STRATOCUMULUS
DECK PROVIDING FAIR WEATHER ACROSS THE MAJORITY OF THE BASIN.

$$
CANGIALOSI


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