[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041739
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT AUG 04 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...
HIGH AMPLITUDE TROPICAL WAVE EXTENDS ACROSS THE CAPE VERDE
ISLANDS ALONG 24W S OF 22N MOVING W NEAR 15 KT. THIS WAVE
CONTINUES TO EXHIBIT A LARGE WELL DEFINED AREA OF CYCLONIC
TURNING IN THE LOW AND MID LEVEL CLOUDS WITH THE GREATEST
ROTATION CURRENTLY ACROSS THE ISLANDS. DEEP CONVECTION REMAINS
MINIMAL NEAR THIS ROTATION THOUGH. THE MORE PERSISTENT SCATTERED
SHOWER/TSTM ACTIVITY HAS BEEN ACROSS THE SRN PORTION OF THE
WAVE AND THE INTERSECTION OF THE ITCZ FROM 7N-14N BETWEEN
22W-29W.

TROPICAL WAVE IS ALONG 40W/41W S OF 18N MOVING W NEAR 15 KT.
THIS WEAK WAVE REMAINS DIFFICULT TO LOCATE AS IT IS EMBEDDED IN
THE FLOW OF THE LARGER WAVES TO IT'S E AND W. STABLE SAHARAN
DUST SURROUNDS THIS FEATURE...JUDGING BY THE CIMSS SAL PRODUCT
AND THE HAZY LOOK ON VISIBLE IMAGES. ISOLATED SHOWERS AND TSTMS
NEAR THE AXIS ARE MORE LIKELY ASSOCIATED WITH THE ITCZ.

HIGH AMPLITUDE TROPICAL WAVE IS ALONG 56W/57W MOVING W 15-20 KT.
THIS LARGE-SCALE WAVE REMAINS EASILY SEEN WITH A PRONOUNCED
INVERTED-V SHAPE NOTED IN THE LOW AND MID LEVEL CLOUD FIELD. IN
ADDITION...THREE BUOYS IN THE VICINITY OF 15N56W HELP DEPICT THE
AXIS WELL SHOWING THE CLASSIC WIND SHIFT AND RELATIVE LOW
PRESSURE AS COMPARED TO THE ENVIRONMENT. THIS WAVE HAS GAINED
SOME DEEP MOISTURE TODAY BUT THIS IS LIKELY CONTRIBUTED TO THE
INTERACTION WITH AN UPPER LOW NEAR 22N59W. SCATTERED SHOWERS AND
TSTMS ARE WITHIN 150 NM EITHER SIDE OF THE AXIS.

STRONG TROPICAL WAVE IS MOVING THROUGH THE NW CARIBBEAN AND
CENTRAL AMERICA ALONG 83W/84W S OF 23N MOVING W NEAR 20 KT. THIS
WAVE HAS BECOME A LITTLE BETTER ORGANIZED TODAY WITH SFC OBS AND
VISIBLE SATELLITE IMAGES SHOWING IMPROVED CURVATURE TO THE
OVERALL STRUCTURE. CONVECTION HAS ALSO INCREASED SOME WITH
SCATTERED MODERATE COVERING THE AREA WITHIN 150 NM EITHER SIDE
OF THE WAVE AXIS. THE STRONGEST CLUSTER IS NEAR THE BASE OF THE
WAVE...PULLED NWD FROM THE ITCZ...S OF 13N BETWEEN 76W-80W. A
QSCAT PASS AROUND 11Z DEPICTED AN INCREASE IN ELY TRADES ALONG
AND TO THE E OF THE WAVE. FURTHER DEVELOPMENT IS NO LONGER
ANTICIPATED SINCE THE VORTICITY MAXIMUM IS OVER LAND.

THE NRN PORTION OF A TROPICAL WAVE ALONG 94W EXTENDS ACROSS THE
BAY OF CAMPECHE S OF 21N MOVING W 15-20 KT. THIS WAVE REMAINS
WEAK WITH THE CURRENT PSN BASED MOSTLY ON A MODEST WWD SURGE OF
MOISTURE...NOTED ON THE UW-CIMSS TPW PRODUCT. SHOWERS AND TSTMS
ARE LIMITED.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N17W 11N25W 8N39W 12N50W 12N55W.
BESIDES FOR THE CONVECTION DISCUSSED WITH THE TROPICAL
WAVES...ISOLATED MODERATE IS WITHIN 180 NM EITHER SIDE OF THE
AXIS BETWEEN 38W-44W AND FROM 6N-10N E OF 18W.

...DISCUSSION...
THE GULF OF MEXICO...
THE WEATHER ACROSS THE GULF IS QUIETER TODAY THAN THE PAST FEW
DAYS AS THE OLD TRAILING FRONTAL BOUNDARY HAS NOW DISSIPATED AND
A WEAK 1019 MB HIGH HAS DEVELOPED IN THE MID-GULF. STILL...SFC
SWLY RETURN FLOW AND A WEDGE OF REMNANT UPPER MOISTURE IS
SUPPORTING ISOLATED SHOWERS AND TSTMS ROUGHLY NW OF A LINE FROM
NRN MEXICO TO THE FL BIG BEND AREA ALONG 23N98W 29N83W. DRY
STABLE AIR ALOFT LIES ABOVE MUCH OF THE REMAINDER OF FLORIDA AND
THE SE GULF BRINGING A SUNNY WARM/HOT SUMMER DAY.
HOWEVER...RATHER ABUNDANT DEEP MOISTURE IS NOT FAR AWAY IN THE
NW CARIB. THIS IS ASSOCIATED WITH THE NRN PART OF THE ACTIVE
TROPICAL WAVE OVER CENTRAL AMERICA. SOME OF THIS MOISTURE SHOULD
SPREAD INTO THE BAY OF CAMPECHE LATE TONIGHT AND TOMORROW AS THE
WAVE CONTINUES W. SFC WINDS ARE LIGHT TO MODERATE AND FLOW
ANTICYCLONICALLY AROUND THE AFOREMENTIONED HIGH NEAR 27N88W.

THE CARIBBEAN SEA...
THE MAIN FEATURE IN THE CARIB IS THE ACTIVE TROPICAL WAVE MOVING
OVER CENTRAL AMERICA. FOR DETAILS REFER TO THE TROPICAL WAVES
SECTION ABOVE. OTHERWISE...THIS REGION REMAINS RATHER TRANQUIL
WITH UPPER NELY FLOW DRAWING DRIER AIR INTO MOST OF THE CENTRAL
AND ERN PORTIONS. THE ATMOSPHERE IS A LITTLE MORE MOIST ACROSS
THE NRN LEEWARD ISLANDS...CLOSER TO AN UPPER LOW CENTER. WSR-88D
DATA FROM SAN JUAN SHOWS QUICK MOVING STREAMS OF SHOWERS HEADING
TOWARD THE ISLAND FROM THE NE...LIKELY ASSOCIATED IN PART WITH
THAT ACTIVITY. AN INCREASE IN MOISTURE IS LIKELY OVER THE NEXT
COUPLE OF DAYS AS THE LARGE TROPICAL WAVE IN THE TROPICAL ATLC
APPROACHES. TRADES ARE ON THE FRESH TO STRONG SIDE IN THE
CENTRAL AND W CARIB N OF 12N W OF 70W...LIKELY ENHANCED SOME BY
THE STRONG TROPICAL WAVE.

THE ATLANTIC OCEAN...
A STALLED FRONT LINGERS TO THE N OF OUR NRN BORDER ACROSS
BERMUDA. ATTM...THIS BOUNDARY HAS LIMITED UPPER SUPPORT DUE TO A
STRONG UPPER RIDGE CENTERED TO IT'S S NEAR 27N73W. HOWEVER...A
SHORTWAVE ALONG THE U.S. E COAST SHOULD HELP GIVE THIS FRONT A
KICK SHORTLY. THE UPPER RIDGE IS SUPPLYING THE BAHAMAS...FLORIDA
AND THE SURROUNDING ATLC WATERS W OF 70W WITH FAIR WEATHER.
DEBRIS MOISTURE...FROM THE ACTIVITY ALONG THE FRONT...IS GETTING
PUSHED SWD BY STRONG NLY WINDS BETWEEN THE UPPER HIGH AND AN
UPPER LOW NEAR 22N59W. THE INTERACTION BETWEEN THIS UPPER LOW
AND A HIGH AMPLITUDE TROPICAL WAVE HAS ALSO SET UP SOME SHOWER
ACTIVITY FROM 14N-26N BETWEEN 50W-59W...SEE ABOVE.

THE REMAINDER OF THE UPPER PATTERN IS RATHER BENIGN WITH OVERALL
LITTLE SIGNIFICANT MOISTURE BEING PRODUCED. THE SFC PATTERN IS
DOMINATED BY A RIDGE EXTENDING FROM A 1028 MB HIGH NEAR 35N36W
TO A 1020 MB CENTER NEAR 27N71W CONTINUING W INTO THE GULF. THE
COMBINATION OF THIS HIGH PRES AND A LARGE AREA OF STABLE AIR
ALOFT IS PRODUCING WIDESPREAD FAIR WEATHER N OF 18N E OF 50W.
TYPICAL STABLE SCATTERED LOW-LEVEL STRATOCUMULUS ARE THE MAIN
SOURCE OF CLOUD COVER ACROSS THIS REGION. TRADES ARE
MODERATE...EXCEPT NEAR THE CARIB ISLANDS AND THE COAST OF NW
AFRICA WHERE THE TIGHTENED PRES GRAD IS PRODUCING SLIGHTLY
STRONGER WINDS.

$$
CANGIALOSI




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