Home › discussion
 

Keywords :   


Tag: discussion

Tropical Depression KAREN Forecast Discussion Number 12

2013-10-06 04:55:49| National Hurricane Center (Atlantic)

Issued at 1000 PM CDT SAT OCT 05 2013 000 WTNT42 KNHC 060255 TCDAT2 TROPICAL DEPRESSION KAREN DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013 1000 PM CDT SAT OCT 05 2013 KAREN HAS ESSENTIALLY REMAINED STATIONARY FOR THE LAST SEVERAL HOURS AND THAT LACK OF MOTION...COUPLED WITH INCREASING UPPER-LEVEL WINDS AHEAD OF AN EASTWARD-MOVING DEEP-LAYER TROUGH...HAS INCREASED THE SHEAR SIGNIFICANTLY ACROSS THE CYCLONE. THE RESULT IS THAT CONVECTION HAS WEAKENED AND BECOME DISPLACED WELL TO THE EAST AND SOUTHEAST OF THE LOW-LEVEL CIRCULATION CENTER. SATELLITE CLASSIFICATIONS FROM TAFB SUPPORTED KEEPING KAREN AS A BORDERLINE TROPICAL STORM AT 00Z...BUT THE LACK OF CONVECTION NEAR THE CENTER SINCE THEN REQUIRES A DOWNGRADE TO DEPRESSION STATUS AT THE 03Z ADVISORY TIME. GIVEN THAT THE VERTICAL WIND SHEAR IS FORECAST TO GET EVEN STRONGER OVER THE NEXT 2 DAYS...RE-STRENGTHENING BACK TO TROPICAL STORM STATUS IS NOT LIKELY...ESPECIALLY SINCE THE MID-LEVELS OF THE TROPOSPHERE WILL BECOME INCREASINGLY DRIER AS WELL...PREVENTING THE RE-DEVELOPMENT OF DEEP CONVECTION OVER THE CENTER. AS A RESULT...TROPICAL STORM WARNINGS HAVE BEEN DISCONTINUED. THE STATIONARY MOTION OF KAREN THE PAST 6-9 HOURS HAS BEEN DUE TO A NORTHWEST-TO-SOUTHEAST ORIENTED MID-/UPPER-LEVEL RIDGE LOCATED ACROSS FLORIDA AND THE SOUTHEASTERN UNITED STATES...WHICH HAS BLOCKED ANY EASTWARD MOTION BY THE CYCLONE. THIS BLOCKING PATTERN IS EXPECTED TO SHIFT SLOWLY EASTWARD OVER THE NEXT TWO DAYS... ALLOWING KAREN OR ITS REMNANTS TO MOVE IN A EASTWARD TO EAST-NORTHEASTWARD DIRECTION UNTIL THE CYCLONE DISSIPATES IN 48-72 HOURS OR IS ABSORBED BY AN APPROACHING FRONTAL SYSTEM. THE NHC FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY AND THE CONSENSUS MODEL TVCA...AND SHOWS KAREN PASSING NEAR OR OVER THE EXTREME SOUTHEASTERN TIP OF LOUISIANA IN ABOUT 24 HOURS...AND REMAINING JUST OFFSHORE OF THE NORTHERN GULF COAST AFTER THAT. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 28.1N 91.9W 30 KT 35 MPH 12H 06/1200Z 28.7N 90.7W 30 KT 35 MPH 24H 07/0000Z 29.1N 88.4W 30 KT 35 MPH 36H 07/1200Z 29.3N 86.1W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 08/0000Z 29.5N 83.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 09/0000Z...DISSIPATED $$ FORECASTER STEWART

Tags: number discussion karen tropical

 

Tropical Storm KAREN Forecast Discussion Number 10

2013-10-05 16:32:46| National Hurricane Center (Atlantic)

Issued at 1000 AM CDT SAT OCT 05 2013 000 WTNT42 KNHC 051432 TCDAT2 TROPICAL STORM KAREN DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013 1000 AM CDT SAT OCT 05 2013 THE LOW-LEVEL CENTER OF KAREN REMAINS EXPOSED ABOUT 100 N MI TO THE WEST-NORTHWEST OF THE DEEP CONVECTION. BASED ON SEVERAL SFMR WINDS AROUND 35 KT FROM THE EARLIER AIRCRAFT MISSIONS IN KAREN EARLY THIS MORNING...THE INITIAL INTENSITY REMAINS 35 KT. THE NEXT AIRCRAFT MISSIONS INTO KAREN THIS AFTERNOON WILL HELP DETERMINE IF THE CYCLONE HAS WEAKENED TO A DEPRESSION. THE ENVIRONMENT REMAINS UNFAVORABLE FOR INTENSIFICATION AND MOST OF THE GUIDANCE SHOWS GRADUAL WEAKENING. THE NEW NHC FORECAST SHOWS THE SYSTEM WEAKENING TO A DEPRESSION IN 24 HOURS. THERE IS LITTLE DIFFERENCE IN IMPACTS BETWEEN A 30-KT DEPRESSION AND A 35-KT TROPICAL STORM...AND TROPICAL STORM FORCE GUSTS COULD EASILY OCCUR IN CONVECTIVE BANDS. KAREN SHOULD DISSIPATE OR BE ABSORBED BY A COLD FRONT SHORTLY AFTER 48 HOURS. KAREN HAS BEEN MOVED QUICKLY NORTH-NORTHWESTWARD OVER THE PAST FEW HOURS...AND THE INITIAL POSITION IS TO THE LEFT AND AHEAD OF THE PREVIOUS FORECAST TRACK. THE INITIAL MOTION ESTIMATE IS NOW 355/07...AS KAREN HAS NOW TURNED NORTHWARD. A SHARP NORTHEASTWARD TURN IS SHOWN BY ALL OF THE GUIDANCE IN THE NEXT 24 HOURS AHEAD OF A MID/UPPER-LEVEL TROUGH...WITH AN EAST-NORTHEASTWARD MOTION AND AN INCREASE IN FORWARD SPEED EXPECTED THROUGH DISSIPATION. THE MORE NORTHERLY INITIAL POSITION RESULTS IN A NORTHWARD SHIFT OF THE NHC TRACK...WHICH NOW TAKES THE CENTER OVER SOUTHEASTERN LOUISIANA AND THEN ALONG THE GULF COAST THROUGH 36 HOURS BEFORE MOVING FARTHER INLAND. IT IS WORTH NOTING THAT THE ECMWF...WHICH HAS PERFORMED QUITE WELL WITH KAREN...TAKES A WEAKER SYSTEM ALMOST DUE EASTWARD AFTER 24 HOURS...AND THIS MOTION CANNOT BE RULED OUT IF THE CYCLONE DECOUPLES AND IS STEERED BY THE LOW-LEVEL FLOW. USERS SHOULD NOT FOCUS ON THE DETAILS OF THE TRACK FORECAST NOW THAT KAREN IS A WEAKER SYSTEM WITH THE CONVECTION WELL REMOVED FROM THE CENTER...SINCE THE TRACK OF THE CENTER WILL HAVE LESS BEARING ON WHERE THE SENSIBLE WEATHER IMPACTS WILL OCCUR. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 27.9N 91.7W 35 KT 40 MPH 12H 06/0000Z 28.7N 91.5W 35 KT 40 MPH 24H 06/1200Z 29.4N 90.3W 30 KT 35 MPH...INLAND 36H 07/0000Z 30.3N 88.1W 30 KT 35 MPH...NEAR THE COAST 48H 07/1200Z 31.3N 85.3W 25 KT 30 MPH...INLAND 72H 08/1200Z...DISSIPATED $$ FORECASTER BRENNAN

Tags: number discussion storm karen

 
 

Tropical Storm KAREN Forecast Discussion Number 9

2013-10-05 10:47:47| National Hurricane Center (Atlantic)

Issued at 400 AM CDT SAT OCT 05 2013 000 WTNT42 KNHC 050847 TCDAT2 TROPICAL STORM KAREN DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013 400 AM CDT SAT OCT 05 2013 KAREN REMAINS A SHEARED CYCLONE THIS MORNING...WITH THE MAIN CONVECTIVE AREA LOCATED ABOUT 80 N MI SOUTHEAST OF THE CENTER. EARLIER ASCAT OVERPASSES INDICATE WINDS OF AT BEST 35 KT IN THE NORTHEASTERN QUADRANT. THERE ARE RECENT REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT OF STRONGER WINDS IN THE CONVECTION...BUT IT IS UNCLEAR HOW REPRESENTATIVE THESE WINDS ARE. THE INITIAL INTENSITY IS DECREASED TO 35 KT BASED ON THE SCATTEROMETER DATA. KAREN JOGGED A BIT NORTHWESTWARD DURING THE PAST SEVERAL HOURS...BUT IT APPEARS TO HAVE RESUMED A NORTH-NORTHWESTWARD MOTION OF 330/7. THE LOW/MID-LEVEL RIDGE CURRENTLY STEERING KAREN SHOULD WEAKEN TODAY AS A DEEP-LAYER TROUGH AND ASSOCIATED COLD FRONT MOVE EASTWARD THROUGH THE CENTRAL UNITED STATES. THIS SHOULD CAUSE KAREN TO TURN NORTHWARD AND THEN NORTHEASTWARD DURING THE NEXT COUPLE OF DAYS. WHILE THE TRACK GUIDANCE AGREES WITH THIS SCENARIO...THERE REMAINS SOME SPREAD ON THE TIMING OF THE NORTHEASTWARD TURN. THE NEW TRACK FORECAST IS NUDGED NORTHWARD BASED ON THE INITIAL POSITION AND MOTION...AND IT CALLS FOR THE CENTER TO PASS NEAR OR OVER THE MOUTH OF THE MISSISSIPPI RIVER IN 24-36 HOURS...FOLLOWED BY A FINAL LANDFALL IN ALABAMA OR THE WESTERN FLORIDA PANHANDLE BETWEEN 36-48 HOURS. THE NEW FORECAST TRACK LIES NEAR THE CENTER OF THE GUIDANCE ENVELOPE. THERE ARE SEVERAL POSSIBLE SCENARIOS FOR THE LOW CONFIDENCE INTENSITY FORECAST. THE MOST LIKELY SCENARIO...AND THE ONE USED IN THE NEW INTENSITY FORECAST...IS THAT KAREN REMAINS A SHEARED SYSTEM WITH LITTLE CHANGE IN STRENGTH UNTIL FINAL LANDFALL. ONE ALTERNATIVE IS POSSIBLE STRENGTHENING BEFORE LANDFALL DUE TO RE-DEVELOPED CENTRAL CONVECTION. WHILE THE DYNAMICAL MODELS FORECAST UPPER-LEVEL WINDS THAT COULD ALLOW THIS TO HAPPEN...THEY ARE FOR THE MOST PART SHOWING NO SIGNIFICANT STRENGTHENING AS KAREN APPROACHES LANDFALL. A SECOND ALTERNATIVE IS THAT KAREN WEAKENS BELOW TROPICAL STORM STRENGTH BEFORE LANDFALL DUE TO EITHER LACK OF CONVECTION OR THE START OF EXTRATROPICAL TRANSITION. AFTER LANDFALL...KAREN SHOULD WEAKEN AND BECOME EXTRATROPICAL AS IT MERGES WITH THE COLD FRONT. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 27.1N 91.3W 35 KT 40 MPH 12H 05/1800Z 27.6N 91.2W 35 KT 40 MPH 24H 06/0600Z 28.4N 90.5W 35 KT 40 MPH 36H 06/1800Z 29.5N 89.2W 35 KT 40 MPH 48H 07/0600Z 31.2N 86.4W 30 KT 35 MPH...INLAND 72H 08/0600Z 35.5N 80.5W 25 KT 30 MPH...POST-TROP/EXTRATROP 96H 09/0600Z...DISSIPATED $$ FORECASTER BEVEN

Tags: number discussion storm karen

 

Tropical Storm KAREN Forecast Discussion Number 7

2013-10-04 22:40:18| National Hurricane Center (Atlantic)

Issued at 400 PM CDT FRI OCT 04 2013 000 WTNT42 KNHC 042040 TCDAT2 TROPICAL STORM KAREN DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013 400 PM CDT FRI OCT 04 2013 AFTER A BURST OF DEEP CONVECTION NEAR AND EAST OF THE CENTER EARLIER THIS AFTERNOON...THE LOW-LEVEL CENTER OF KAREN IS AGAIN EXPOSED WEST OF THE WARMING CLOUD TOPS. DATA FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE THAT THE INTENSITY OF KAREN REMAINS 45 KT...AND A CENTER DROP FROM THE PLANE REPORTED A PRESSURE OF 1003 MB. MODERATE SHEAR AND DRY AIR SHOULD RESULT IN LITTLE OVERALL INTENSITY CHANGE DURING THE NEXT 24 HOURS...EVEN THOUGH SHORT TERM CHANGES IN CONVECTIVE ORGANIZATION COULD RESULT IN SOME SHORT TERM FLUCTUATIONS IN INTENSITY. THE GLOBAL MODELS ARE NOW IN BETTER AGREEMENT ON THIS EVOLUTION...AND SHOW THE MID-LEVEL CIRCULATION WEAKENING OR DISSIPATING ENTIRELY IN THE NEXT DAY OR TWO. IN PARTICULAR THE GFS IS WEAKER WITH ITS FORECAST OF KAREN AFTER DATA FROM THE NOAA GULFSTREAM-IV JET...WHICH SHOWED 200-MB WINDS WEST OF KAREN STRONGER THAN PREVIOUSLY ANALYZED...WERE INCORPORATED INTO THE 12Z ANALYSIS. AFTER 24 HOURS...KAREN COULD STRENGTHEN A LITTLE DUE TO AN INCREASE IN UPPER-LEVEL DIVERGENCE AHEAD OF A MID-LATITUDE TROUGH...BUT SIGNIFICANT STRENGTHENING IS NOT EXPECTED. AN ALTERNATIVE SCENARIO IS THAT KAREN COULD BECOME COMPLETELY DECOUPLED FROM THE DEEP CONVECTION AND WEAKEN. THE INITIAL MOTION OF KAREN HAS VARIED DEPENDING ON HOW CLOSE THE CONVECTION WAS TO THE CENTER. AFTER MOVING MORE NORTHWARD EARLIER THE AFTERNOON THE CENTER HAS WOBBLED WESTWARD AS IT BECAME EXPOSED. SMOOTHING THROUGH THESE SHORT TERM VARIATIONS...THE INITIAL MOTION ESTIMATE IS 335/06. THE GLOBAL MODELS ARE NOW IN A LITTLE BETTER AGREEMENT ON THE HEADING OF THE STORM OVER THE NEXT COUPLE OF DAYS...IN PARTICULAR THE GFS HAS SHIFTED TO THE LEFT AND IS NOW CLOSER TO THE ECMWF. HOWEVER...THERE REMAIN LARGE DIFFERENCES IN FORWARD SPEED WITH THE GUIDANCE CONTINUING TO TREND SLOWER OVERALL. THE NHC FORECAST SHOWS A TURN TOWARD THE NORTH BY 24 HOURS AND THEN A SHARP NORTHEASTWARD TURN BY 36 HOURS AS KAREN FEELS THE INFLUENCE OF THE AFOREMENTIONED TROUGH. THE NHC TRACK HAS BEEN ADJUSTED TOWARD THE SLOWER MULTI-MODEL CONSENSUS...BUT IS FASTER AND TO THE LEFT OF THE ECMWF AND GFS AFTER 24 HOURS. CONFIDENCE IN THE DETAILS OF THE TRACK FORECAST...AND THEREFORE THE DISTRIBUTION OF IMPACTS ALONG THE COAST...REMAINS LOW. GIVEN THE NEW INTENSITY FORECAST...THE HURRICANE WATCH HAS BEEN CHANGED TO A TROPICAL STORM WATCH FROM THE MOUTH OF THE PEARL RIVER TO DESTIN FLORIDA...AND DISCONTINUED ELSEWHERE. THE 12Z HWRF RUN SHOWED CONSIDERABLY LESS INTENSIFICATION WITH KAREN COMPARED TO PREVIOUS RUNS AFTER ASSIMILATING DATA FROM THE FROM THE NOAA P-3 TAIL DOPPLER RADAR. THIS MARKS THE FIRST TIME DOPPLER RADAR DATA HAVE BEEN ASSIMILATIED INTO AN OPERATIONAL HURRICANE MODEL IN REAL TIME. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 25.9N 90.3W 45 KT 50 MPH 12H 05/0600Z 26.9N 90.6W 45 KT 50 MPH 24H 05/1800Z 27.9N 90.7W 45 KT 50 MPH 36H 06/0600Z 28.8N 89.6W 50 KT 60 MPH 48H 06/1800Z 29.9N 87.7W 50 KT 60 MPH 72H 07/1800Z 33.0N 82.5W 25 KT 30 MPH...POST-TROP/EXTRATROP 96H 08/1800Z...ABSORBED $$ FORECASTER BRENNAN

Tags: number discussion storm karen

 

Tropical Storm KAREN Forecast Discussion Number 6

2013-10-04 16:32:10| National Hurricane Center (Atlantic)

Issued at 1000 AM CDT FRI OCT 04 2013 000 WTNT42 KNHC 041432 TCDAT2 TROPICAL STORM KAREN DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013 1000 AM CDT FRI OCT 04 2013 AFTER BEING DISPLACED WELL EAST OF THE LOW-LEVEL CENTER OF KAREN... DEEP CONVECTION HAS RECENTLY DEVELOPED A LITTLE CLOSER TO THE CENTER OVER THE PAST HOUR OR TWO...BUT THE CYCLONE IS STILL BEING AFFECTED BY 20-25 KT OF WESTERLY SHEAR AND DRY AIR BEING ADVECTED INTO THE CYCLONE. THE LAST CENTRAL PRESSURE REPORTED BY THE AIRCRAFT WAS 1003 MB...AND BASED ON THE LATEST ROUND OF AIRCRAFT DATA THE INTENSITY HAS BEEN REDUCED TO 45 KT. THE ENVIRONMENT DOES NOT LOOK FAVORABLE FOR SIGNIFICANT INTENSIFICATION...WITH MODERATE SHEAR EXPECTED TO CONTINUE FOR THE NEXT DAY OR TWO. HOWEVER...IF THE SHEAR DOES LESSEN...EVEN FOR A SHORT PERIOD OF TIME...DEEP CONVECTION COULD RE-DEVELOP CLOSER TO THE CENTER AND ALLOW FOR SOME INTENSIFICATION. IN ADDITION...BY 48 HOURS UPPER-LEVEL DIVERGENCE AHEAD OF AN APPROACHING MID/UPPER-LEVEL TROUGH COULD ALLOW FOR SOME STRENGTHENING. THE NEW NHC INTENSITY FORECAST HAS BEEN ADJUSTED DOWNWARD AND SHOWS LITTLE CHANGE IN THE NEXT 24 HOURS AND A STRENGTHENING TO 55 KT BY 48 HOURS. THE INITIAL MOTION HAS BEEN WOBBLING BETWEEN 325 AND 330 DEGREES AT ABOUT 9 OR 10 KT OVER THE PAST FEW HOURS. THE FUTURE TRACK WILL BE QUITE SENSITIVE TO THE STRUCTURE OF KAREN OVER THE NEXT COUPLE OF DAYS. IN THE SHORT TERM A WEAKER SHALLOWER SYSTEM WILL BE STEERED MORE TOWARD THE LEFT BY THE LOW-LEVEL FLOW...WHILE A DEEPER MORE VERTICALLY COHERENT CYCLONE WOULD TURN NORTHWARD MORE QUICKLY DUE TO A MID-LEVEL RIDGE TO THE EAST. GIVEN THE CURRENT APPEARANCE OF KAREN AND THE CONTINUED SHEAR...THE NHC TRACK HAS BEEN ADJUSTED A LITTLE TO THE LEFT DURING THE FIRST 24 HOURS TOWARD THE UKMET AND ECMWF MODELS...WHICH SHOW A WEAKER SYSTEM. ALL OF THE GUIDANCE SHOWS A NORTHEASTWARD TURN IN 36 TO 48 HOURS...BUT WITH LARGE DIFFERENCES IN THE LATITUDE AT WHICH THE TURN OCCURS AND SIGNIFICANT SPREAD IN WHERE THE CENTER CROSSES THE COAST. AT 36 HOURS AND BEYOND THE NHC TRACK IS CLOSE TO THE ECMWF AND THE MULTI-MODEL CONSENSUS...AND CLOSE TO THE PREVIOUS OFFICIAL FORECAST. GIVEN THE LARGE SPREAD AND THE DEPENDENCE OF THE TRACK ON THE STRUCTURE AND INTENSITY OF KAREN...CONFIDENCE IN THE DETAILS OF THE TRACK FORECAST...AND THEREFORE THE DISTRIBUTION OF IMPACTS ALONG THE COAST...IS LOW. THE NOAA GULFSTREAM-IV JET SAMPLED THE ENVIRONMENT NEAR KAREN AND OVER THE NORTHERN GULF OF MEXICO OVERNIGHT. THESE DATA WILL BE INCORPORATED INTO THE 12Z MODEL CYCLE...AND HOPEFULLY IMPROVE THE ANALYSIS OF THE ENVIRONMENT NEAR AND AHEAD OF THE STORM. GIVEN THE WESTWARD SHIFT IN THE NHC TRACK...THE TROPICAL STORM WARNING HAS BEEN EXTENDED WESTWARD TO MORGAN CITY LOUISIANA. GIVEN THE WEAKENING TREND AND THE REDUCTION IN THE INTENSITY FORECAST...IT HAS BECOME A LITTLE LESS LIKELKY THAT KAREN WILL REACH HURRICANE STRENGTH. IF THESE TRENDS CONTINUE...THE HURRICANE WATCH COULD BE CHANGED TO A TROPICAL STORM WATCH OR WARNING LATER TODAY. FORECAST POSITIONS AND MAX WINDS INIT 04/1500Z 25.6N 90.2W 45 KT 50 MPH 12H 05/0000Z 26.6N 90.7W 45 KT 50 MPH 24H 05/1200Z 27.7N 90.9W 45 KT 50 MPH 36H 06/0000Z 28.6N 90.5W 50 KT 60 MPH 48H 06/1200Z 29.8N 88.6W 55 KT 65 MPH 72H 07/1200Z 33.5N 83.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 96H 08/1200Z...ABSORBED $$ FORECASTER BRENNAN

Tags: number discussion storm karen

 

Sites : [1192] [1193] [1194] [1195] [1196] [1197] [1198] [1199] [1200] [1201] [1202] [1203] [1204] [1205] [1206] [1207] [1208] [1209] [1210] [1211] next »