000 AXNT20 KNHC 131745 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN JUL 13 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND 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 1745 UTC. ...SPECIAL FEATURE.... TROPICAL STORM BERTHA IS CENTERED NEAR 30.0N 63.0W AT 13/1800 UTC ABOUT 165 NM SE OF BERMUDA AND IS STATIONARY. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 991 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. A TROPICAL STORM WARNING IS IN EFFECT FOR BERMUDA. PLEASE READ THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. BERTHA HAS BEEN MEANDERING FOR SOME TIME AS IT HAS BEEN EMBEDDED IN WEAK STEERING CURRENTS...BUT A MOTION TO THE N-NW IS ANTICIPATED OVER THE NEXT COUPLE OF DAYS. IR IMAGERY SHOWS CONVECTION INCREASING SLIGHTLY IN THE NE QUADRANT BETWEEN 90 NM AND 180 NM OF THE CENTER. THE W PERIPHERY OF THIS ACTIVITY IS BEING DETECTED ON DOPPLER RADAR FROM BERMUDA AND IS CURRENTLY ABOUT 80 NM SSE OF THE ISLAND. CONVECTION HAS CHANGED LITTLE IN A BAND TO THE S AND SE OF THE CENTER...WITHIN 90-120 NM. STRONG TROPICAL WAVE IS ALONG 37W/38W S OF 17N MOVING W 10-15 KT. A 1009 MB LOW IS ANALYZED ALONG THE AXIS NEAR 9N. VISIBLE SATELLITE IMAGES SHOWS A LARGE WELL DEFINED ENVELOPE OF CYCLONIC TURNING...FOCUSED NEAR THE LOW CENTER. SHIP TBWUK18 REPORTED 27 KT S WINDS SE OF THE LOW CENTER AT 12Z...UNFORTUNATELY BOTH ASCAT AND QSCAT MISSED THE REGION. A LARGE AREA OF SCATTERED MODERATE AND EMBEDDED ISOLATED STRONG CONVECTION IS WITHIN 240 NM W AND 60 NM E SEMICIRCLES. SIMILAR CONVECTION IS LOCATED WITHIN THE INTERSECTION OF THE ITCZ FROM 4N-8N BETWEEN 36W-44W. THIS SYSTEM HAS THE POTENTIAL TO BECOMING A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF DAYS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 56W/57W S OF 16N MOVING W 15 KT. SYNOPTIC OBSERVATIONS FROM TRINIDAD AND TOBAGO...BARBADOS...ST LUCIA AND OTHER ISLANDS ALL SHOW 24-H PRES FALLS OF ABOUT 3 MB IN ASSOCIATION WITH THE APPROACH OF THE WAVE. THIS FEATURE HAS BEEN WELL DEFINED FOR DAYS...HOWEVER ITS MOISTURE FIELD HAS FLATTENED SOME TODAY BASED ON THE MIMIC TPW ANIMATION. SCATTERED SHOWERS AND TSTMS ARE WITHIN 200 NM W OF THE WAVE S OF 12N AND E OF THE AXIS FROM 10N-12N BETWEEN 49W-52W. TROPICAL WAVE HAS BEEN ADJUSTED W ALONG 85W/86W S OF 20N MOVING W 15 KT. THE UPDATED POSITION WAS MAINLY BASED ON THE SOUTHERN PART OF THE WAVE IN THE EPAC WHERE A LOW PRESSURE SYSTEM HAS FORMED. THAT LOW IS BEING MONITORED FOR DEVELOPMENT...REFER TO THE EAST PACIFIC...TWDEP...FOR MORE DETAILS. LIKE THE WAVE TO ITS E...24-H SLP FALLS ARE ABOUT 2-3 MB OVER THE YUCATAN PENINSULA...HONDURAS AND OTHER PARTS OF CENTRAL AMERICA IN ASSOCIATION WITH THE WAVE AND DEVELOPING LOW. SFC PRESSURE FALLS ARE OF SIMILAR MAGNITUDE OVER CUBA...BUT THIS COULD ALSO BE ASSOCIATED WITH TROUGHING OVER FLORIDA AND THE E GULF. SCATTERED MODERATE CONVECTION IS S OF 15N W OF 78W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N14W 10N26W 11N34W 8N39W 9N55W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N OF THE AXIS BETWEEN 19W-21W AND FROM 4N-7N BETWEEN 13W-19W. ...DISCUSSION... THE GULF OF MEXICO... AN UPPER RIDGE CENTERED OVER TEXAS AND AN UPPER LOW OVER THE BAHAMAS IS INDUCING NE TO E FLOW ALOFT OVER THE GULF. A MID-LEVEL PERTURBATION OR SHORTWAVE COMBINED WITH THE TAIL END OF A SFC TROUGH FROM NEAR ST AUGUSTINE FLORIDA TO 24N88W IS TRIGGERING SCATTERED SHOWERS AND TSTMS WITHIN 75 NM OF A NW-SE LINE FROM 30N80W TO 25N82W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING IN THE BAY OF CAMPECHE IN THE VICINITY OF A SMALL UPPER LOW CENTERED NEAR 20N95W. OTHERWISE...STABLE AIR ALOFT W OF 90W AND WEAK SFC HIGH PRES CENTERED NEAR 27N92W IS PROVIDING THE REMAINDER OF THE AREA WITH LIGHT WINDS AND FAIR WEATHER. THE CARIBBEAN SEA... UPPER DIFFLUENCE BETWEEN TROUGHING OVER E CUBA/JAMAICA AND A FLAT RIDGE ALONG 12N W OF 70W IS PRODUCING A LARGE AREA OF SCATTERED SHOWERS AND TSTMS S OF 15N W OF 76W. LOW-LEVEL CONVERGENCE ASSOCIATED WITH THE ITCZ AND ENHANCED LIFT BY A TROPICAL WAVE ALONG 86W IS CONTRIBUTING TO THE AFOREMENTIONED TSTM ACTIVITY. ANOTHER TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES WITH THE W PERIPHERY OF THE DEEPER SCATTERED SHOWERS AND TSTMS NEARING TRINIDAD AND TOBAGO. THE REMAINDER OF THE E CARIBBEAN IS FAIRLY TRANQUIL AS A SUBSIDENT ENVIRONMENT IS IN PLACE. THIS IS CAPPING THE TYPICAL QUICK MOVING STREAMS OF LOW-LEVEL SHOWERS. TRADE WINDS ARE ON THE STRONG SIDE (20-25 KT) OVER THE S CENTRAL CARIBBEAN AND THESE WINDS WILL LIKELY CHANGE LITTLE OVER THE NEXT COUPLE OF DAYS. THE ATLANTIC OCEAN... A WEAK FRONT OR TROUGH EXTENDS OFF THE SE U.S. COAST FROM A 1012 MB LOW NEAR 32N78W ACROSS NE FLORIDA AND INTO THE GULF OF MEXICO. WHILE MUCH OF THE SHOWER ACTIVITY ASSOCIATED WITH THE FRONTAL LOW HAS DIMINISHED...IT IS BEING MONITORED FOR THE POSSIBILITY OF DEVELOPMENT. AN UPPER LOW SITUATED OVER THE NE BAHAMAS NEAR 25N76W IS PRODUCING A FAIR AMOUNT OF CLOUDINESS AND LIGHTNING DATA INDICATES A SMALL AREA OF TSTMS BETWEEN SE FLORIDA AND THE NW BAHAMAS. ELSEWHERE...BESIDES FOR BERTHA AND THE TROPICAL WAVES...THE REMAINDER OF THE DISCUSSION ZONE IS DEVOID OF SIGNIFICANT DEEP CONVECTION. THE MID AND UPPER PATTERN CONSISTS OF AN UPPER TROUGH TO BERTHA'S E ALONG 42W N OF 18N WITH AN ASSOCIATED WEAK SFC BOUNDARY ANALYZED FROM 32N46W TO 28N51W. SCATTERED SHOWERS ARE POSSIBLE WITHIN 120 NM OF THE SFC TROUGH. BROAD RIDGING COVERS MUCH OF THE E ATLC WITH THE RIDGE AXIS ALONG 19N/20N AND ANOTHER HIGH NEAR 16N50W. UPPER CONFLUENCE IS DRYING THE ATMOSPHERE N OF 23N E OF 35W. IN THE LOWER LEVELS...SFC RIDGING DOMINATES MUCH OF THE PATTERN EXTENDING S AND SW FROM A 1029 MB HIGH NEAR THE AZORES. A WEAK TROUGH WAS WELL DETECTED IN THE ASCAT DATA FROM 26N26W TO 31N28W PRODUCING A FEW SHOWERS AND INCREASING E WINDS TO 20 KT WITHIN 180 NM E OF THE AXIS. SFC REPORTS FROM THE LESSER ANTILLES AND THE HAZY LOOK ON VISIBLE IMAGES ACROSS THE TROPICAL ATLC...SUGGEST THE PRESENCE OF SAHARAN DUST S OF 25N E OF 62W. $$ CANGIALOSI