[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210540
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON APR 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 4N20W 3N32W 1N40W TO THE
EQUATOR AT 50W. SCATTERED MODERATE TO STRONG CONVECTION IS
WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 25W-32W. SCATTERED
MODERATE CONVECTION IS FROM 4N-6N BETWEEN 33W-48W.

...DISCUSSION...

GULF OF MEXICO...
A MID TO UPPER LEVEL RIDGE IS BUILDING E OVER THE REGION
OVERTAKING TROUGHING OVER FLORIDA. THIS WEAKENING TROUGH
...ASSOCIATED WITH A CUT OFF LOW OVER THE MID-ATLANTIC
STATES...IS PROVIDING LIMITED SUPPORT FOR A COLD FRONT FROM
SOUTHWEST FLORIDA TO 25N89W. THE FRONT IS ONLY MARKED BY A
NARROW BROKEN LINE OF LOW CLOUDS WITH EMBEDDED SCATTERED
SHOWERS...AS INDICATED ON DOPPLER RADAR. A WEAK 1016 MB HIGH IS
SITUATED BEHIND THE FRONT CENTERED OVER THE N CENTRAL WATERS
NEAR 29N87W. MAINLY FAIR WEATHER AND LIGHT TO MODERATE WINDS
DOMINATES THE MAJORITY OF THE REGION SUPPORTED BY A SUBSIDENT
ENVIRONMENT...ESPECIALLY OVER THE SW PORTION. THE FRONT IS
EXPECTED TO CONTINUE TO WEAKEN AND SHIFT SE ALLOWING FAIR
WEATHER TO CONTINUE OVER THE NEXT DAY OR TWO.

CARIBBEAN SEA...
A BROAD UPPER TROUGH LIES OVER THE CARIBBEAN SEA AND FLAT
RIDGING COVERS MUCH OF THE TROPICAL ATLC AND SOUTH AMERICA. THIS
LARGE SCALE PATTERN IS PRODUCING A MODERATE TO STRONGLY
SUBSIDENT ENVIRONMENT N OF 14N. S OF 14N...THE ATMOSPHERE IS
BEING SOMEWHAT MOISTENED ALOFT BY THIN BROKEN HIGH LEVEL CLOUDS.
IN THE LOWER LEVELS...A 2302 Z QSCAT PASS SUGGESTS THAT NE WINDS
HAVE DECREASED TO 20-25 KT NEAR THE COAST OF COLOMBIA WITH
MODERATE TRADES NOTED ELSEWHERE. THE TYPICAL LOW-LEVEL CLOUD
PATCHES APPEAR SUBDUED TONIGHT WITH THE ONLY ORGANIZED PATCH
OVER THE NRN LEEWARD ISLANDS. THE TRADE WIND FLOW IS EXPECTED TO
WEAKEN FURTHER ON MON AS TROUGHING BECOMES BETTER ESTABLISHED
OVER THE W ATLC. OTHERWISE...LITTLE SIGNIFICANT CHANGE IS
EXPECTED OVER THE NEXT DAY OR SO.

ATLANTIC OCEAN...
A LARGE SCALE TROUGH...WITH A FEW EMBEDDED SHORTWAVES...COVERS
MUCH OF THE W ATLC. ONE OF THE SHORTWAVES IS SUPPORTING A COLD
FRONT FROM 32N76W TO S FLA. DOPPLER RADAR AND LIGHTNING DATA IS
SHOWING QUITE A BIT OF TSTM ACTIVITY ALONG THE BOUNDARY N OF THE
DISCUSSION ZONE...HOWEVER...ONLY ISOLATED SHOWERS AND TSTMS ARE
LIKELY WITHIN 60 NM E OF THE FRONT S OF 32N. SCATTERED SHOWERS
AND TSTMS ARE ALSO LOCATED N OF PUERTO RICO FROM 21N-24N BETWEEN
64W-68W. THIS ACTIVITY IS ASSOCIATED WITH BASE OF THE SHARP
UPPER TROUGH (VORTICITY MAX) AND LOW-LEVEL CONVERGENCE ALONG A
LINGERING SFC TROUGH. DEBRIS MID-HIGH LEVEL CLOUDS COMBINED WITH
LOW LEVEL CLOUDS ALONG THE SFC TROUGH FROM 31N51W TO 23N59W IS
PRODUCING A FAIR AMOUNT OF CLOUD COVER AND ISOLATED SHOWERS
WITHIN 150 NM OF THE SFC TROUGH LINE.

THE CENTRAL AND EASTERN ATLC IS DOMINATED BY A QUASI-STATIONARY
1025 MB HIGH NEAR 30N34W. THIS HIGH IS PRODUCING A LARGE AREA OF
15-20 KT NE/E WINDS ACROSS THE TROPICAL BELT. IN THE MID AND
UPPER LEVELS...A BROAD RIDGE COVERS MUCH OF THE REGION BETWEEN
25W-50W AND UPPER TROUGHING LIES OVER THE THE NE PORTION FROM
THE MADEIRA ISLANDS TO 17N32W. DIFFLUENCE ALOFT TO THE E OF THE
TROUGH AXIS IS GENERATING/TRANSPORTING MID-HIGH LEVEL CLOUDS
WITHIN 300 NM E OF THE TROUGH LINE...INCLUDING THE CAPE VERDE
ISLANDS. BROAD FLAT RIDGING LIES OVER THE TROPICS ENHANCING
CONVECTION IN THE ITCZ W OF 25W.

$$
CANGIALOSI




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