[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212356
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU JUN 21 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 31W/32W S OF 13N MOVING W NEAR 15 KT.
ASSOCIATED NE-SE WIND SHIFT IS SEEN AT LOW LEVELS. THE SHOWER
ACTIVITY REMAINS MINIMAL AND MOSTLY AHEAD OF THE WAVE AXIS
EMBEDDED IN THE ITCZ.

A TROPICAL WAVE IS ALONG 44W S OF 12N MOVING W 10 T0 15 KT.
CONVECTION HAS SLIGHTLY INCREASE ALONG THE WAVE AXIS BUT NEAR
THE ITCZ.

A TROPICAL WAVE EXTENDS FROM HISPANIOLA TO WESTERN VENEZUELA
ALONG 72W S OF 21N MOVING W NEAR 15 KT. THIS WAVE IS HELPING TO
ENHANCE SOME SHOWER ACTIVITY OVER HISPANIOLA.

A TROPICAL WAVE HAS BEEN ADDED ON THE 18Z MAP ALONG 81W/82W
SOUTH OF 18N BASED ON THE PROPAGATION OF THE CONVECTION OBSERVED
IN THE HOVMOLLER DIAGRAM. A 1009 MB LOW IS ALONG THE WAVE AXIS
NEAR 11N. CURRENTLY...SATELLITE IMAGERY SHOWS A LARGE AREA OF
DISTURBED WEATHER ASSOCIATED WITH THE WAVE AND THE LOW PRESSURE
OVER THE WESTERN CARIBBEAN SEA AND PORTIONS OF CENTRAL AMERICA.
WHILE CONDITIONS DO NOT APPEAR FAVORABLE FOR DEVELOPMENT...THIS
SYSTEM COULD PRODUCE LOCALLY HEAVY RAINFALL OVER PORTIONS OF
CENTRAL AMERICA DURING THE NEXT DAY OR SO AS IT MOVES SLOWLY
WESTWARD.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N13W 7N30W 8N40W 8N50W 6N60W.
SCATTERED MODERATE CONVECTION IS FROM 4N-10N BETWEEN 35W-46W.
CLUSTERS OF MODERATE CONVECTION ARE SEEN FROM FRENCH GUIANA TO
EASTERN VENEZUELA.

...DISCUSSION...

THE GULF OF MEXICO...
WEAK LOW PRES TROUGHING COVERS THE E GULF ASSOCIATED WITH A SLOW
MOVING 1013 MB FRONTAL LOW CENTERED ABOUT 50 MILES SOUTHEAST OF
JACKSONVILLE FLORIDA. DOPPLER RADAR SHOWS LINES OF SCATTERED
SHOWERS AND TSTMS MOVING SOUTH OVER N-CENTRAL FLORIDA ASSOCIATED
WITH THE CIRCULATION OF THE LOW. MODEST RIDGING COVERS THE
REMAINDER OF THE GULF. THIS OVERALL WEAK PRES PATTERN IS
PROVIDING THE AREA WITH LIGHT WINDS AND LOW SEAS. ALOFT...THE
FLOW IS PRIMARILY NLY ON THE ERN PERIPHERY OF A HIGH CENTERED
OVER WEST-CENTRAL MEXICO NEAR 20N100W. THESE WINDS ARE ADVECTING
ABUNDANT UPPER LEVEL MOISTURE OVER THE WESTERN GULF. A WEAK
TROUGH ALONG 87W/88W IS INTERRUPTING THE RIDGING ALLOWING MOST
OF THE UPPER FLOW TO BE LIGHT IN ITS VICINITY. NWP MODELS
GENERALLY SHOW LITTLE MOVEMENT OF THE LOW OR REMNANT TROUGH
WHILE THE WEAK RIDGE OF HIGH PRES OVER NW GULF WILL PERSIST
TROUGH THE WEEKEND. THIS WILL ALLOW THE SFC FLOW TO REMAIN LIGHT
FOR A COUPLE OF DAYS MORE. THEREAFTER...SFC WINDS AND MOISTURE
MAY INCREASE ACROSS THE SRN WATERS AS THE NRN EXTENSION OF THE W
CARIB TROPICAL WAVE APPROACHES.

THE CARIBBEAN SEA...
CLUSTERS OF MODERATE TO STRONG CONVECTION ARE OVER THE WESTERN
CARIBBEAN AND PARTS OF CENTRAL AMERICA ASSOCIATED WITH A
TROPICAL WAVE AND A BROAD AREA OF LOW PRESSURE. DIFFLUENCE
ASSOCIATED WITH AN UPPER HIGH LOCATED NEAR 12N80W IS ENHANCING
THIS CONVECTIVE ACTIVITY. ANOTHER TROPICAL WAVE IS OVER THE
CENTRAL CARIBBEAN. SEE TROPICAL WAVES SECTION. ALOFT...AN UPPER
HIGH REMAINS E OF THE WINDWARD ISLANDS NEAR 12N55W WITH A RIDGE
EXTENDING WWD TO 70W. THIS RIDGE IS GIVING THE REGION UPPER DRY
AIR/SUBSIDENCE. WLY UPPER WINDS DOMINATES THE AREA N OF 17N EAST
OF 80W. THESE WINDS ARE TRANSPORTING ABUNDANT UPPER LEVEL
MOISTURE ACROSS THE NORTHERN CARIBBEAN INTO THE ATLANTIC OCEAN
BEYOND 55W. 20 TO 30 KT TRADE WINDS ARE BLOWING ACROSS THE
BASIN. THESE STRONG WINDS ARE ANTICIPATED TO PERSIST AND EXPAND
SLIGHTLY WWD OVER THE NEXT COUPLE DAYS AS THE ATLC RIDGE N OF
THE AREA STRENGTHENS.

THE ATLANTIC OCEAN...
A 1013 MB FRONTAL LOW IS SITUATED APPROXIMATELY 50 MILES
SOUTHEAST OF JACKSONVILLE FLORIDA. DISORGANIZED SHOWERS AND
THUNDERSTORMS ARE ASSOCIATED WITH THIS FEATURE. THERE ARE NO
SIGNS OF ORGANIZATION AND UPPER LEVEL WINDS ARE NOT FAVORABLE
FOR DEVELOPMENT. FARTHER EAST...AN UPPER TROUGH CUTS ACROSS THE
AREA FROM 32N62W SW TO THE SE BAHAMAS. STRONG SWLY WINDS AHEAD
OF THE TROUGH AXIS ARE SHEARING THE TROPICAL WAVE NOW LOCATED
OVER HISPANIOLA. OTHERWISE...A SFC HIGH PRES RIDGE IS IN CONTROL
OF THE E-CENTRAL ATLC RUNNING FROM A 1029 MB HIGH S OF THE
AZORES NEAR 36N25W TO A 1022 MB CENTER NEAR 25N55W. THIS RIDGE
IS ALLOWING WINDS TO BE LIGHT TO MODERATE ACROSS MOST OF THE
ATLC DISCUSSION AREA. THE EXCEPTION IS NEAR THE AFRICAN COAST
WHERE THE PRES GRADIENT IS TIGHTENED BETWEEN THE AZORES HIGH AND
INVERTED TROUGHING OVER THE CONTINENT. NE WINDS OF 20 TO 25 KT
ARE SEEN E OF 25W FROM THE CAPE VERDE ISLANDS TO THE MADEIRA AND
CANARY ISLANDS. THE COMBINATION OF THIS HIGH PRES ALONG WITH DRY
STABLE AIR ALOFT ASSOCIATED WITH AN UPPER RIDGE ALONG 24W/25W IS
PROVIDING TRANQUIL CONDITIONS ACROSS THE E AND MOST OF THE
TROPICAL ATLC WITH ONLY PATCHES OF LOW/MID CLOUDS.

$$
GR





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