[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171018
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU APR 17 2008

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 4N4W 3N10W 4N24W 2N35W 4N44W 2N52W.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-9N BETWEEN
12W-15W AND 45 NM OF LINE FROM 3N11W TO 2N16W. CLUSTERS
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 6N TO S
OF THE EQUATOR W OF 30W TO INLAND OVER SOUTH AMERICA.

...DISCUSSION...

GULF OF MEXICO...
UPPER RIDGE ANCHORED OFF THE W COAST OF CENTRAL AMERICA IN THE E
PACIFIC REGION COVERS THE W GULF WITH THE AXIS EXTENDING FROM
THE BAY OF CAMPECHE TO THE COAST OF TEXAS NEAR CORPUS CHRISTI.
BROAD DEEP LAYERED TROUGH COVERS THE REMAINDER OF THE GULF E OF
90W INTO THE W ATLC AND DIPPING S INTO THE NW CARIBBEAN. ALL OF
THIS IS PROVIDING STRONG SUBSIDENCE AND DRY AIR TO THE GULF. A
SURFACE RIDGE EXTENDS FROM NEW ENGLAND OVER THE SE US INTO THE
GULF WITH A 1024 MB HIGH OVER SE GEORGIA. RETURN SOUTHERLY FLOW
AROUND THE SURFACE RIDGE IS BANKING COLD AIR STRATOCUMULUS
CLOUDS ACROSS THE CENTRAL GULF MOSTLY WITHIN 120 NM OF LINE FROM
23N86W TO 28N92W. SOME ISOLATED SHOWERS ARE MOVING FROM THE W
ATLC THROUGH THE FLORIDA STRAITS S OF THE FLORIDA KEYS TO CUBA E
OF 84W. OTHERWISE THE GULF REMAINS RELATIVELY CLEAR THIS
MORNING. THE NEXT COLD FRONT IS EXPECTED TO ENTER THE NW GULF
FRI...BUT WILL NOT BE AS STRONG AS THE PREVIOUS FRONT AND WILL
BRING THE CHANCE OF SHOWERS TO THE W GULF EARLY ON FRI.

CARIBBEAN SEA...
THE DEEP LAYERED TROUGH FROM THE W ATLC EXTENDS OVER THE NW
CARIBBEAN TO JUST S OF THE CAYMAN ISLANDS FROM HISPANIOLA TO THE
YUCATAN CHANNEL. THE ASSOCIATED STATIONARY FRONT CROSSES
HISPANIOLA EXTENDING A SURFACE TROUGH S OF THE SOUTHERN
PENINSULA OF HAITI TO 17N79W GENERATING SCATTERED SHOWERS WITHIN
120 N OF THE FRONT/TROUGH. UPPER WESTERLY FLOW DOMINATES THE
REMAINDER OF THE CARIBBEAN. MODERATE/STRONG NE TO E TRADE WINDS
ARE ACROSS THE CARIBBEAN WITH THE HIGHEST WINDS AGAIN THIS
MORNING OVER THE E CARIBBEAN...ALONG THE COAST OF COLOMBIA...AND
IN THE WINDWARD PASSAGE. THESE TRADE WINDS COUPLED WITH THE
FRONTAL BOUNDARY ARE BANKING LOW CLOUDS WITH ISOLATED SHOWERS
WITHIN 120 NM OF LINE FROM E CUBA NEAR 20N76W W OF JAMAICA TO
THE TIP OF HONDURAS/NICARAGUA. CONVERGENCE OF THE UPPER LEVEL
WINDS AND SURFACE FLOW OVER THE SW CARIBBEAN IS GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90 NM ALONG THE
COAST OF CENTRAL AMERICA S OF 11N W OF 80W.

ATLANTIC OCEAN...
BROAD DEEP LAYERED TROUGH COVERS THE W ATLC W OF 60W WITH THE
MAIN UPPER LOW N OF THE REGION AND A SECOND UPPER LOW NEAR
31N72W. AT THE SURFACE...A COLD FRONT ENTERS THE REGION E OF
BERMUDA NEAR 32N63W S ALONG 23N66W THEN SW ACROSS HISPANIOLA
NEAR 18N71W CONTINUING INTO THE CARIBBEAN AS A SURFACE TROUGH.
HEAVY SHOWERS WITH CLUSTERS OF ISOLATED THUNDERSTORMS ARE WITHIN
90/120 NM E OF THE FRONT N OF 22N WITH SCATTERED SHOWERS S OF
23N WITHIN 150 NM W OF THE FRONT AND 90 NM E OF THE FRONT. A
SURFACE TROUGH EXTENDS FROM THE 1001 MB LOW N OF THE REGION SW
ALONG 29N69W THEN OVER THE CENTRAL BAHAMA ISLANDS TO NEAR
23N77W. ISOLATED SHOWERS DOT THE REMAINDER OF THE AREA W OF THE
FRONT TO 81W AND THE COAST OF FLORIDA. BROAD DEEP LAYERED RIDGE
COVERS THE REMAINDER OF THE ATLC WITH THE UPPER RIDGE ANCHORED
BY AN UPPER HIGH NEAR 28N32W AND THE SURFACE 1030 MB HIGH
ANCHORED NEAR 33N43W. THE TYPICAL E/W UPPER RIDGE ACROSS THE
TROPICS HAS BEEN SUPPRESSED TO THE S BY THIS STRONG UPPER RIDGE
TO THE N AND GENERATING A SHEAR AXIS EXTENDING FROM W AFRICA
NEAR 20N16W ALONG 15N30W TO 21N42W. THUS GIVING THE ATLC E OF
60W FAIR WEATHER THIS MORNING.

$$
WALLACE



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