[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 152328
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT 15 JAN 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN
COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 2N0 EQ13W 4.5N30W 4N40W 2N55W. DRY
DUSTY AIR FROM W AFRICA HAS PENETRATED SWD TO THE ITCZ W OF
ABOUT 40W TO THE GULF OF GUINEA. ISOLATED SHOWERS WITHIN 75 NM
OF THE AXIS BETWEEN 11W-17W. SCATTERED MODERATE CONVECTION
WITHIN 75 NM OF THE AXIS BETWEEN 22W-34W. SCATTERED MODERATE UP
TO 275 NM N OF THE AXIS BETWEEN 34W-45W. ISOLATED MODERATE ALONG
COASTAL AREAS FROM BRAZIL TO GUYANA.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL TROF...WITH A WAVELENGTH OF ABOUT 3500
NM...SPANS A GOOD CHUNK OF THE ATLC OCEAN AND CONUS WITH THE
STRONGEST VORTICITY CURRENTLY ROUNDING THE BASE NEAR
TEXAS/OKLAHOMA. THE STRONG POLAR JET REMAINS N OF THE AREA BUT A
100 KT SUBTROPICAL JET IS ORIENTED E/W FROM THE RIO GRANDE
VALLEY TO THE NRN GULF COAST AND IS BRINGING HIGH LEVEL CLOUDS
ACROSS THE AREA N OF 25N. THE COLD FRONT HAS BLOWN THROUGH THE
REGION AND LEFT MOSTLY BROKEN SKIES OVER THE WATER...WITH THE
CLOUDS BECOMING MORE OVERCAST WITHIN ABOUT 120 NM OF THE W
FLORIDA COAST CLOSER TO THE FRONTAL WAVE NEAR THE NRN BAHAMAS.
THICK CLOUDS ALSO EXTEND OFF THE E SLOPES OF THE SIERRA MADRES S
OF 23N WITH THE CONTINUANCE OF OROGRAPHIC LIFTING. BUILDING HIGH
PRES OVER THE MIDWEST U.S. WILL SEND A SECOND SURGE OF COLDER
AIR SWD OVER THE GULF WATERS TONIGHT AND SUN...MOST LIKELY
INCREASING CLOUD COVERAGE AS THE ATMOSPHERE DESTABILIZES OVER
THE RELATIVELY WARM WATER.

FLORIDA AND WEST ATLANTIC...
A STATIONARY FRONTAL BOUNDARY SITS JUST OFF THE FLORIDA E COAST
ALONG 32N73W 29N78W TO THE ISLE OF YOUTH IN CUBA WITH A 1016 MB
FRONTAL LOW CENTERED NEAR FREEPORT BAHAMAS. ALTHOUGH THE UPPER
LEVEL PATTERN CANNOT PUSH THE FRONT ANY FARTHER E...DIFFLUENT
FLOW ALOFT IS STILL PRODUCING WIDELY SCATTERED SHOWERS PRIMARILY
250 NM SE OF THE FRONT OVER THE GULF STREAM AND NRN BAHAMAS.
DOPPLER RADAR FROM FLORIDA SHOWS MODERATE/HEAVY RAIN FALLING
OVER GRAND BAHAMA ISLAND AND THE ADJACENT COASTAL WATERS WHILE
THE FRONTAL LOW FLINGS WIDELY SCATTERED SHOWERS SWWD OVER THE
CNTRL FLORIDA COAST BETWEEN VERO BEACH AND DAYTONA BEACH. THE
LOW WILL SKIRT NEWD TO OFF THE MID-ATLC COAST DURING THE NEXT 24
HRS AND THEN THE SECOND SURGE OF COLDER AIR THAT WILL RUSH IN
OVER THE GULF OF MEXICO TONIGHT AND SUN WILL PUSH THE FRONT
FARTHER E BY MON AFTERNOON.

CARIBBEAN...
THE W ATLC STATIONARY FRONT EXTENDS ACROSS W CUBA TO NE HONDURAS
THEN SNAKES SW/W ALONG A LINE FROM TEGUCIGALPA TO GUATEMALA CITY
TO CHIAPAS MEXICO. STRONG NLY FLOW BEHIND THE FRONT IS BRINGING
ISOLATED SHOWERS SWD OVER THE GULF OF HONDURAS WHILE LOW CLOUDS
AND SHOWERS ARE BEING OROGRAPHICALLY INDUCED OVER HONDURAS AND
NRN GUATEMALA. A SHEARED UPPER TROF EXTENDS FROM THE CAYMAN
ISLANDS TO THE GULF OF TEHUANTEPEC AND IS PRODUCING A NARROW
SWATH OF STRONG SUBSIDENCE...PREVENTING DEEP CONVECTION ALONG
THE FRONT. ELSEWHERE...DRY AIR DOMINATES THE REGION AMONG
WESTERLY UPPER FLOW WHILE ONLY OCCASIONAL SHOWERS DRIFT WWD
ACROSS THE SRN WINDWARD ISLANDS.

ATLANTIC...
STRONG HIGH PRES N OF THE AREA CONTINUES TO PRODUCE A STRONG
PRES GRADIENT ACROSS MOST OF THE ATLC WATERS WITH EASTERLY WINDS
BETWEEN 25-30 KT. THE MOST NOTABLE FEATURE IN SATELLITE IMAGERY
IS A LARGE AREA OF MID/UPPER LEVEL CLOUDS AND EMBEDDED SHOWERS
BETWEEN 30W-60W. ONE PART OF THIS ACTIVITY IS BEING CAUSED BY A
NEGATIVELY TILTED TROF ALONG 26N62W 16N55W WHICH IS PRODUCING
SCATTERED SHOWERS E OF ITS AXIS FROM 18N-26N BETWEEN 47W-59W.
THEN...A 90-110 KT SUBTROPICAL JET IS PULLING WIDESPREAD
MOISTURE UP FROM THE RAINFORESTS OF BRAZIL AND ADVECTING IT
ACROSS THE ATLC S OF 22N. SOME DEEP CONVECTION IS LOCATED NEAR
THE ITCZ BUT MOST OF THE TROPICS ARE ONLY COVERED BY THESE
MID/UPPER CLOUDS. FARTHER E...A SHARP AND NEARLY STATIONARY
UPPER TROF IS LOCATED N/NW OF THE CANARY ISLANDS WITH A
DISSIPATING COLD FRONT EXTENDING ALONG 32N16W 23N30W 22N40W. A
130 KT JET EXTENDS ALONG THE W SIDE OF THE UPPER TROF NEAR THE
AZORES AND WILL PROPAGATE SWD...DEEPENING THE TROF AND PRODUCING
A DEEP-LAYERED CUT-OFF LOW NEAR THE CANARY ISLANDS IN 24-48 HRS.
PROGS OF MOISTURE AND VERTICAL LIFT FROM THE GFS INDICATE THAT
RAIN WILL BEGIN TO SPREAD OVER THE ISLANDS TOMORROW AND CONTINUE
FOR MOST OF THE WEEK AS THE LOW BECOMES NEARLY STATIONARY AND
DRAWS LARGE AMOUNTS OF TROPICAL AIR NEWD ALONG THE SUBTROPICAL
JET. FLOODING IS A POSSIBILITY ESPECIALLY ON THE WESTERNMOST
ISLANDS AS SEVERAL INCHES OF RAIN IS EXPECTED TO FALL SUN
THROUGH TUE.

$$
BERG



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