[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 101122
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SAT MAR 10 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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
1115 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N12W 4N25W 2N42W CROSSING THE
EQUATOR NEAR 48W INTO NE BRAZIL. SCATTERED MODERATE CONVECTION
IS WITHIN 120 NM SOUTH OF THE AXIS BETWEEN 31W-41W AND WITHIN 90
NM N OF THE AXIS W OF 45W. SIMILAR CONVECTION EXISTS OVER NE
BRAZIL. SCATTERED SHOWERS AND TSTMS ARE WITHIN 90 NM EITHER SIDE
OF THE AXIS BETWEEN 18W-22W.

...DISCUSSION...

GULF OF MEXICO...
STRONG ZONAL MID TO UPPER LEVEL PATTERN HAS SET UP IN THE GULF
SANDWICHED BETWEEN A DIGGING SHORTWAVE TROUGH OVER THE
CENTRAL/EASTERN U.S. AND WEAK RIDGING OVER CENTRAL AMERICA. THIS
STRONG FLOW ALOFT IS SPREADING A PLUME OF MOISTURE ACROSS
CENTRAL/SOUTHERN MEXICO AND THE GULF S OF 27N. MOST OF THIS IS
ONLY IN THE FORM OF BROKEN/OVERCAST MID TO HIGH LEVEL CLOUD DECK
AND A POSSIBLE ISOLATED SHOWER IN THE BAY OF CAMPECHE. IN THE
LOWER LEVELS...WEAK HIGH PRES RIDGING IS THE THEME EXTENDING SW
FROM A STRONG HIGH WELL OFF THE MID-ATLANTIC COAST. A VERY WEAK
SFC TROUGH...DEPICTED BY A SLIGHT WIND SHIFT OR PERTURBATION IN
THE LIGHT ELY FLOW IN QSCAT AND SHIP OBS...IS NEARLY STATIONARY
ALONG 89W FROM 25N-30N. SCATTERED LOW TO MID LEVEL CLOUDS AND
MAYBE A FEW EMBEDDED LIGHT SHOWERS ARE WITHIN 180 NM E OF THE
TROUGH AXIS. LOOKING AHEAD THROUGH THE WEEKEND...THE WEAK TROUGH
WILL GRADUALLY DISSIPATE AS STRONG HIGH PRES BUILDS N OF THE
REGION. THE PRES GRADIENT ON THE S SIDE OF THE HIGH WILL
INCREASE THE SFC EASTERLIES SLIGHTLY ON SUN AND INTO EARLY NEXT
WEEK.

CARIBBEAN...
QUIET WEATHER PERSISTS ACROSS MUCH OF THE BASIN THIS MORNING
WITH PLENTY OF DRY STABLE AIR ALOFT IN PLACE. WEAK UPPER RIDGING
GENERALLY DOMINATES THE REGION AS THE SHORTWAVE TROUGH HAS NOW
PULLED E INTO THE CENTRAL ATLC. THERE ARE ONLY A COUPLE OF AREAS
OF NOTABLE CLOUDINESS. ONE IS OVER COLOMBIA...PANAMA...COSTA
RICA AND THE COASTAL WATERS WHERE THERE ARE SMALL PATCHES OF
WEAKENING SHOWERS MOSTLY ASSOCIATED WITH CLIMATOLOGICAL LOW PRES
AND THE ITCZ. THE OTHER AREA OF CLOUDINESS IS OVER THE ISLAND OF
HISPANIOLA WHERE INFLUENCE FROM A SFC TROUGH TO THE N AND LOCAL
UPSLOPING CONDITIONS IS LIKELY PRODUCING A FEW SHOWERS OVER THE
HIGH TERRAIN...BUT THIS ACTIVITY HAS JUST ABOUT TURNED OFF OVER
THE PAST FEW HOURS. OTHERWISE MAINLY FAIR WEATHER AND TYPICAL
ISOLATED TRADE WIND SHOWERS ARE MOVING WWD ACROSS THE REGION.
TRANQUIL WEATHER IS EXPECTED TO CONTINUE THROUGH THE WEEKEND
WITH CONDITIONS DOMINATED BY MODERATE TO STRONG TRADE WINDS.

WESTERN ATLANTIC...
A LARGE AREA OF MULTILAYER CLOUDINESS AND SCATTERED
SHOWERS/TSTMS CONTINUE TO AFFECT THE REGION. THE SFC PATTERN
CONTRIBUTING TO THIS UNSETTLED WEATHER HAS BEEN SOMEWHAT
COMPLEX. LAST NIGHT...THE SETUP CONSISTED OF A LOW PRES SYSTEM N
OF THE CENTRAL BAHAMAS WITH AN ASSOCIATED TROUGH EXTENDING SWD
TO THE WINDWARD PASSAGE AND AN APPROACHING COLD FRONT NE OF THE
LOW. OVER THE PAST SEVERAL HOURS...IT HAS BECOME APPARENT ON
SATELLITE IMAGERY THAT THESE FEATURES HAVE MERGED TOGETHER AND
AS OF 06Z A COLD FRONT ENTERED THE AREA NEAR 32N44W TO 29N55W
THEN STATIONARY TO A 1012 MB LOW NEAR 26N72W. A TROUGH REMAINS
FAIRLY DISTINCT FROM THE LOW SWD TO THE WINDWARD PASSAGE. ALL OF
THESE ELEMENTS ALONG WITH STRONG W-SWLY UPPER LEVEL FLOW IS
GENERATING AND ADVECTING MOISTURE MAINLY N OF 24N W OF 50W.
HOWEVER...PRECIP IS NOT REACHING THE GROUND ACROSS THIS ENTIRE
AREA. IR IMAGES SUGGEST THAT SCATTERED SHOWERS AND TSTMS ARE
MOST LIKELY FROM 24N-29N BETWEEN 62W-70W WHERE LIFTING AND
INSTABILITY IS GREATEST. IN ADDITION TO THE MOISTURE...ANOTHER
CONCERN IS THE STRONG NELY WINDS AS A TIGHT PRES GRAD HAS NOW
SET UP BETWEEN THE LOW AND A 1034 MB HIGH NEAR 38N64W. LOOKING
AHEAD IN TIME...THE WEAK LOW IS EXPECTED TO INTENSIFY AND TRACK
TO THE NE. THIS WILL INCREASE THE PRES GRAD FURTHER THROUGHOUT
THE DAY AND FOR THAT REASON A GALE WARNING IS IN EFFECT FOR A
PORTION OF THE FORECAST AREA. FOR DETAILS REFER TO THE HIGH SEAS
FORECAST UNDER AWIPS HEADER MIAHSFAT2.

EASTERN ATLANTIC...
STRONG HIGH PRES RIDGING CONTINUES TO DOMINATE THE SFC PATTERN
ACROSS THE ATLC E OF 45W. THIS HIGH IS PRODUCING MODERATE TO
STRONG TRADE WINDS ACROSS A GOOD PORTION OF THE DISCUSSION AREA
PARTICULARLY N OF 20 E OF 25W WHERE THE TIGHTEST PRES GRAD
EXISTS. IN THE MID AND UPPER LEVELS...STRONG RIDGING IS ALSO THE
RULE WITH THE AXIS ALIGNED ROUGHLY ALONG 30W. ABUNDANT DRY
SUBSIDENT FLOW ALOFT IS WIDESPREAD AIDING IN THE FAIR WEATHER
ACROSS THIS REGION. OVER THE NEXT FEW DAYS...THE STRONG RIDGING
WILL RETREAT NE ALLOWING THE TRADES TO RELAX SLIGHTLY TODAY
ESPECIALLY IN THE E ATLC. HOWEVER THEY ARE SET TO PICK UP AGAIN
FROM W TO E SUN AND INTO NEXT WEEK AS STRONG HIGH PRES REBUILDS
E ACROSS THE ATLC OCEAN. THE UPPER RIDGE IS FORECAST TO SHIFT W
AS A SHARP TROUGH DEVELOPS IN THE E ATLC N OF THE REGION...THIS
SHOULD ALLOW FAIR WEATHER TO CONTINUE FOR THE BULK OF THE AREA.

$$
CANGIALOSI




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