[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 082334
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED AUG 08 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...
WEAK LOW AMPLITUDE TROPICAL WAVE IS ALONG 34W S OF 14N MOVING W
10-15 KT. THIS WAVE REMAINS DIFFICULT TO LOCATE DUE TO MULTIPLE
LOW LEVEL SWIRLS IN THE VICINITY EMBEDDED WITHIN THE ITCZ. THE
OVERALL LOW-LEVEL FLOW IS UNIFORM NELY N OF THE ITCZ AND THE
UW-CIMSS TPW PRODUCT SHOWS ALMOST NO MOISTURE PERTURBATION IN
THE AREA...THUS CURRENT PSN IS BASED MOSTLY ON FORWARD
EXTRAPOLATION. ISOLATED SHOWERS AND TSTMS ARE CONFINED TO THE
ITCZ.

TROPICAL WAVE IS ALONG 53W/54W S OF 23N MOVING W 15-20 KT. THIS
HIGH AMPLITUDE WAVE CONTINUES TO BE CLEARLY DEFINED ON THE
UW-CIMSS TPW PRODUCT...ALTHOUGH IT'S CONSIDERABLY LESS MOIST
THAN THE PREVIOUS FEW DAYS. A LOW-LEVEL CIRCULATION HAS BECOME
EVIDENT ALONG THE AXIS...WITHIN THE ITCZ...NEAR 12N. THE
REMAINDER OF THE WAVE HAS A SURGE-LIKE STRUCTURE WITH MINIMAL
CONVECTION.

TROPICAL WAVE IS ALONG 62W S OF 17N MOVING W 15-20 KT. DECIDED
TO ADJUST THIS WAVE SLIGHTLY TO THE W BASED ON A SHIFT TO THE SE
IN THE FLOW ACROSS THE SRN WINDWARDS. SCATTERED MODERATE
CONVECTION HAS FLARED UP A BIT OVER THE PAST COUPLE OF HOURS TO
THE E OF THE WAVE AXIS...SHEARED BY UPPER WLY WINDS...ACROSS THE
ERN ISLANDS FROM 8N-14N BETWEEN 58W-62W.

TROPICAL WAVE IS ALONG 81W S OF 19N MOVING W NEAR 15 KT. EXACT
WAVE PSN REMAINS DIFFICULT TO LOCATE WITH CONVENTIONAL
SATELLITE IMAGERY OR SFC OBS. THE TROUGHING FURTHER E MOVING
THROUGH THE CENTRAL CARIB AND SW ATLC IS A MORE SIGNIFICANT
FEATURE AT THE MOMENT. THERE CONTINUES TO BE SOME DEBATE ON
WHETHER OR NOT THIS FEATURE IS A TROPICAL WAVE BUT HAVE
MAINTAINED CONTINUITY ANALYZING IT AS A SFC TROUGH...AS IT IS
DIFFICULT TO TELL IF THIS FEATURE ORIGINATED OVER AFRICA. THIS
ANALYZED TROUGH...IS LIKELY A COMBINATION OF SFC TROUGHING
ASSOCIATED WITH AN UPPER LOW...A PIECE/BRANCH OF A TROPICAL WAVE
AND AN EASTERLY SURGE. MORE ON THIS FEATURE IN THE DISCUSSION
SECTION BELOW.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N17W 11N33W 14N48W 12N61W. THE
AXIS REMAINS VERY QUIET ACROSS THE ITCZ THIS EVENING WITH NO
SIGNIFICANT CONVECTION ALONG THE AXIS OUTSIDE OF THE AREAS
ASSOCIATED WITH THE TROPICAL WAVES.

DISCUSSION...
GULF OF MEXICO...
FAIRLY QUIET WEATHER CONTINUES ACROSS THE GULF OF MEXICO AS A
LARGE STRONG UPPER HIGH REMAINS PARKED OVER THE SOUTHEAST U.S.
THIS SPRAWLING RIDGE HAS CONTRIBUTED TO THE VERY HOT WEATHER
ACROSS THE SE/MID-ATLANTIC STATES. STRONG ELY UPPER FLOW...ON
THE S SIDE OF THIS RIDGE...COVERS THE NRN PORTION OF THE GULF
TRANSPORTING A MID-HIGH LEVEL CLOUD DECK ACROSS THE AREA E OF
87W. THE ATMOSPHERE DRIES OUT W OF THERE AS THE FLOW BECOMES
CONFLUENT IN RESPONSE TO INVERTED TROUGHING OVER THE SW GULF. AT
THE SFC...A 1018 MB HIGH HAS BEEN QUASI-STATIONARY S OF TEX/LA
BORDER NEAR 28N93W. THIS CONTINUES TO PRODUCE FAIRLY LIGHT
WINDS/LOW SEAS FOR THE GULF WHICH IS GENERALLY EXPECTED TO
PERSIST OVER THE NEXT COUPLE OF DAYS.

CARIBBEAN SEA...
SCATTERED SHOWERS AND TSTMS ARE AFFECTING A GOOD PORTION OF THE
CENTRAL AND E CARIB...ROUGHLY E OF 72W. THIS UNSETTLED WEATHER
IS ASSOCIATED WITH A COMPLEX TROUGH OF LOW PRES...A TROPICAL
WAVE MOVING THRU THE LESSER ANTILLES AND AN UPPER LOW OVER
CENTRAL CUBA. THE SFC TROUGH AXIS IS ANALYZED ACROSS HAITI TO
NRN VENEZUELA ALONG 20N72W 10N70W. SFC OBS AND EARLIER QSCAT AND
ASCAT PASSES SUGGESTS CONSIDERABLY STRONGER WINDS E OF THIS
AXIS. ALTHOUGH FURTHER DEVELOPMENT IS NOT EXPECTED...MODEL
GUIDANCE SHOWS A FAIR AMOUNT OF MOISTURE SPREADING WWD ACROSS
THE CARIB OVER THE NEXT COUPLE OF DAYS. FURTHER W...CLOUDINESS
AND SCATTERED SHOWERS COVER MUCH OF THE AREA S OF 14N W OF 72W
ASSOCIATED WITH DIFFLUENCE ALOFT AND THE ITCZ. CONDITIONS ARE
TRANQUIL ACROSS THE NW CARIB...BESIDES FOR TYPICAL AFTERNOON
LAND ACTIVITY AND DEBRIS SHOWERS OVER THE SEA.

ATLANTIC OCEAN...
THE REGION W OF 72W IS PRETTY QUIET UNDER STRONG NELY UPPER FLOW
ON THE SE SIDE OF A SPRAWLING UPPER RIDGE OVER THE SE STATES.
MORE ACTIVE WEATHER COVERS THE REGION BETWEEN 62W AND 72W
ASSOCIATED WITH THE NRN PART OF THE CARIBBEAN INVERTED SFC
TROUGH...WHICH  EXTENDS N OF HAITI ALONG 20N72W 28N68W. IN
ADDITION TO THE SFC SUPPORT AN ELONGATED UPPER TROUGH EXTENDING
SW FROM 30N65W TO CENTRAL CUBA NEAR 22N80W. A FEW EMBEDDED WEAK
UPPER LOWS ARE ALSO NOTED IN THIS EVENINGS WV IMAGERY. ALL OF
THIS TROUGHINESS IS PLAYING A PART IN PRODUCING THE DISORGANIZED
ACTIVITY LOCATED WITHIN 300 NM E OF THE SFC TROUGH AXIS.
ELSEWHERE...UPPER RIDGING AND DRY STABLE AIR ALOFT GENERALLY
DOMINATES THE MAJORITY OF THE PATTERN IN THE E ATLC EXCEPT FOR A
WELL DEFINED UPPER LOW NEAR MADEIRA ISLAND. SW FLOW AHEAD OF
THIS SYSTEM IS SHEARING A TROPICAL WAVE APPROACHING THE AFRICAN
COAST SPREADING MOISTURE NEWD ACROSS THE NW PART OF THE
CONTINENT.

THE REMAINDER OF THE SFC PATTERN IS DOMINATED BY A 1028 MB HIGH
NEAR 38N35W. THIS IS PRODUCING WIDESPREAD FAIR WEATHER AND
MODERATE TRADES N OF 15N E OF 45W. NE WINDS REMAIN A LITTLE
STRONGER ALONG THE COAST OF NW AFRICA WHERE THE HIGH INTERACTS
WITH THERMAL TROUGHING OVER AFRICA...BUT THESE WINDS ARE NOT AS
STRONG AS IT HAS BEEN OVER THE LAST COUPLE OF DAYS.

$$
CANGIALOSI


This weather bulletin was brought to you by:
www.nashvilleweather.net