000 AXNT20 KNHC 241759 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST MON DEC 24 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N10W 6N25W 4N40W 2N40W 3N52W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM N OF THE AXIS BETWEEN 37W-40W. ...DISCUSSION... THE GULF OF MEXICO... COLD FRONT THAT MOVED ACROSS THE GULF THE PAST FEW DAYS HAS SLOWED DOWN IN FORWARD SPEED...AND NOW EXTENDS FROM FORTY MYERS FLORIDA SW 25N85W WHERE IT BECOMES A DISSIPATING STATIONARY FRONT TO THE E BAY OF CAMPECHE. THE FRONT IS CHARACTERIZED BY BROKEN PATCHES OF LOW CLOUDS MOVING SW WITH ISOLATED SHOWERS WITHIN 75 NM TO ITS NW. ELSEWHERE SCATTERED TO BROKEN LOW CLOUDS ARE WITHIN 150 NM NW OF THE FRONT IN A VERY STABLE ENVIRONMENT. WATER VAPOR IMAGERY FROM THIS MORNING AND EARLY AFTERNOON SHOWED ABUNDANT MODERATE SUBSIDENCE AND ASSOCIATED DRY AIR COVERING THE GULF SE OF LINE FROM THE FLORIDA BIG BEND SW TO THE BAY OF CAMPECHE. TO THE NW OF THIS LINE...TROPICAL MOISTURE IS SEEN STREAMING NORTHEASTWARD FROM THE E PACIFIC NE ACROSS NORTHERN MEXICO REACHING TO ACROSS THE SE UNITED STATES. THE RESPONSIBLE JETSTREAM BRANCH EXTENDS FROM E PACIFIC NE ACROSS NORTHERN MEXICO WHERE IT ROUNDS THE BASE OF A SHORTWAVE TROUGH MOVE EASTWARD ACROSS CENTRAL AND EASTERN TEXAS...THEN CONTINUES TO STRETCH FURTHER NE TO ACROSS THE MID-ATLANTIC STATES. SATELLITE- DERIVED WINDS INDICATE MAXIMUM WINDS ASSOCIATED WITH THIS JETSTREAM TO BE IN THE RANGE OF 70-100 KT. CURRENTLY...SURFACE WINDS ARE NE IN DIRECTION BEHIND THE FRONT AND IN THE 10-15 KT RANGE UNDER HIGH PRES BOTH AT THE SURFACE AND ALOFT. WITH LITTLE IN THE WAY OF UPPER SUPPORT...IF ANY AT ALL...THE FRONT WILL ONLY SAG SOUTHWARD OVER THE SOUTH CENTRAL FLORIDA THIS AFTERNOON BEFORE BECOMING STATIONARY AND GRADUALLY LOSE ITS IDENTITY THIS EVENING AND THROUGH TUE MORNING. THE SHORTWAVE TROUGH IS FORECAST TO RAPIDLY MOVE E TO OVER THE SE UNITED STATES WITHIN THE NEXT 36-48 HRS AS NEXT COLD FRONT MOVES INTO THE NW GULF WED AFTERNOON AND TO THE CENTRAL GULF BY THU MORNING THEN SLOWS DOWN UNTIL A STRONGER COLD FRONT MOVES OFF THE TEXAS COAST ON FRI AND REACHES TO THE CENTRAL GULF BY FRI EVENING. WITH THE UPPER FLOW PATTERN FORECAST TO RATHER ZONAL OVER MUCH OF THE SOUTHERN UNITED STATES AND NORTHERN GULF THESE FRONTS LIKE THE PRESENT ONE SHOULD NOT PROGRESS TOO FAR S INTO THE AREA. THE CARIBBEAN SEA... AMPLIFIED MID TO UPPER LEVEL RIDGING IS PRESENT OVER THE NW AND CENTRAL SECTIONS OF THE SEA CREATING ABUNDANT MODERATE TO STRONG SUBSIDENCE IN THESE AREAS. THE RETREATING TAIL END OF A MID/UPPER LEVEL TROUGH EXTENDS FROM THE E ATLC SW TO NEAR THE LEEWARD ISLANDS. THIS STABLE ENVIRONMENT CONTINUES TO SUPPRESS DEEP CLOUD DEVELOPMENT AND CONVECTION ALLOWING INSTEAD FOR QUITE CONDITIONS TO PREVAIL. A JETSTREAM BRANCH EXTENDS ROUGHLY FROM 12N82W THROUGH 15N75W THEN ESE THROUGH 14N66W TO E OF THE AREA ACROSS THE WINDWARD ISLANDS. S OF THE JETSTREAM...SCATTERED TO BROKEN HIGH CIRRUS CLOUDS ARE SEEN MOVING QUICKLY EASTWARD. FAST NE-E MOIST TRADE WIND FLOW TO THE S OF THE JETSTREAM IS BRINGING QUICK PASSING SHOWERS TO WATERS OVER THE FAR S SECTION OF THE SEA. THE FLOW IS LEADING TO PRONOUNCED LOW-LEVEL CONVERGENCE EXISTS PRIMARILY S OF 12N W OF 76W INCLUDING THE GULF OF PANAMA WHERE ISOLATED MODERATE TO OCCASIONALLY STRONG CONVECTION IS NOTED. SCATTERED TO LOCALLY BROKEN LOW CLOUDS MOVING QUICKLY WSW WITH ISOLATED SHOWERS ARE NOTED ELSEWHERE ACROSS THE SEA E OF 68W AND ALSO S OF 17N W OF 68W. SCATTERED LOW CLOUDS MOVING SW ARE N OF 17N W OF 77W. EXPECT LARGE NE SWELLS...EXPECTED TO POSSIBLY BUILD IN THE RANGE OF 8-10 FT...TO CONTINUE TO AFFECT THE NE CARIBBEAN AND PASSAGES THROUGH THE END OF THE WEEK. THE ATLANTIC OCEAN... THIS REGION IS DOMINATED PRIMARILY BY TWO MAIN FEATURES. THE FIRST IS A BROAD AREA OF ANTICYCLONIC FLOW PRESENT W OF ABOUT 57W. AMPLE MODERATE TO STRONG SUBSIDENCE IS FOUND HERE WITH MAIN BULK OF UPPER LEVEL MOISTURE SHUNTED JUST TO THE N OF THE AREA AROUND THE NORTHERN PERIPHERY OF THIS AREA. AT THE SURFACE...A WEAK COLD FRONT ENTERS THE REGION THROUGH 32N75W AND EXTENDS SW TO NEAR VERO BEACH FLORIDA AND CONTINUES SW TO NEAR FORT MYERS. BROKEN TO OVERCAST LOW CLOUDS WITH ISOLATED SHOWERS ARE NOTED WITHIN 60-75 NM NW OF THE FRONT. A WEAK SURFACE TROUGH MOVING W 15 KT EXISTS ALONG 75W FROM 22N-29N. ONLY ISOLATED WEAK SHOWERS ARE SEEN WITHIN 45 NM EITHER SIDE OF THE TROUGH. OTHER SCATTERED TO LOCALLY BROKEN LOW CLOUDS WITH ISOLATED SHOWERS PRECEDE THE TROUGH BY ABOUT 240-300 NM AND ARE AFFECTING PARTS OF THE BAHAMA ISLAND CHAIN...AND ARE NOW MOVING INTO THE EASTERN STRAITS OF FLORIDA AS SEEN IN DOPPLER RADAR IMAGERY OUT OF MIAMI AND KEY WEST. EXPECT THIS TREND TO LAST FOR THE NEXT 24-48 HRS. TO THE E OF THE ANTICYCLONIC FLOW AREA...THE UPPER FLOW BECOMES NLY THEN SHARPLY SHIFTS TO SW TO W DUE TO A DEEP-LAYERED TROUGH THAT ENTERS THE FAR E PORTION OF THE AREA THROUGH 32N45W AND EXTENDS TO NEAR THE LEEWARD ISLANDS. AMPLE UPPER LEVEL MOISTURE IN THE FORM OF OVERCAST HIGH CLOUDS IS EVIDENT WITHIN 500 NM SE OF THE TROUGH. THE SURFACE REFLECTION IS IDENTIFIED AS A COLD FRONT ENTERING THE REGION THROUGH 32N35W AND TO 28N45W WHERE IT BECOMES DISSIPATING STATIONARY TO 26N49W AND THEN A TROUGH TO 22N60W. THE SURFACE LOW PREVIOUSLY ANALYZED AS 1015 MB NEAR 23N57W BECAME DIFFUSED THIS MORNING...BUT MODELS SUGGEST THAT A NEW LOW MAY FORM OF 1017 MB FURTHER E ALONG THE BOUNDARY NEAR 26N42W WITHIN THE NEXT 24 HRS NEAR 26N42W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED ALONG AND WITHIN 300 NM SE OF THE FRONT/TROUGH BETWEEN 43-52W UNDER SLIGHTLY UPPER LEVEL DIFFLUENT FLOW WHICH EXTENDS E TO 27W. A WEAK MID LEVEL SHORTWAVE RIDGE IS ALONG 30W N OF 23N. THIS RIDGE MAY AMPLIFY SOME AS IT MOVES EASTWARD THROUGH THU. SCATTERED TO BROKEN LOW AND MID LEVEL CLOUDS WITH EMBEDDED ISOLATED SHOWERS ARE ELSEWHERE WITHIN 330 NM SE OF THE FRONT. THE UPPER FLOW IS GENERALLY ZONAL OVER THE REMAINDER OF THE ATLANTIC TO THE E AND SE OF THE FRONT/TROUGH. HIGH LEVEL MOISTURE STREAMING EASTWARD IS LOCATED S OF 18N. A STATIONARY SURFACE HIGH OF 1032 MB SITUATED NEAR 32N20W HAS A RIDGE EXTENDING SW THROUGH 28N30W AND TO 21N38W. HIGH PRES COVERS THE AREA N OF 14N AND E OF THE FRONT/TROUGH WITH ONLY SCATTERED PATCHES OF BROKEN LOW CLOUDS WITH ISOLATED SHOWERS SEEN HERE THROUGHOUT. $$ AGUIRRE