792  
FXUS02 KWBC 232000  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
400 PM EDT FRI SEP 23 2022  
 
VALID 12Z MON SEP 26 2022 - 12Z FRI SEP 30 2022  
 
...TROPICAL DEPRESSION NINE OVER THE CARIBBEAN LIKELY TO INTENSIFY  
AND MAY AFFECT AT LEAST FLORIDA BY NEXT WEEK...  
 
   
..OVERVIEW
 
 
THE LARGE SCALE PATTERN BEGINS WITH AN AMPLIFIED RIDGE OVER THE  
WEST AND A TROUGH OVER THE EAST THAT WILL FLATTEN WITH TIME AS A  
SHORTWAVE TROUGH APPROACHES FROM THE EASTERN PACIFIC AND MOVES  
INLAND. THE 15Z NATIONAL HURRICANE CENTER ADVISORY FORECASTS A  
TROPICAL DEPRESSION NINE CURRENTLY IN THE CARRIBEAN TO UNDERGO  
RAPID INTENSIFICATION AS IT TRACKS NORTH-NORTHWESTWARD TOWARD THE  
GULF OF MEXICO WITH A LANDFALL IN SOUTH FLORIDA WEDNESDAY MORNING.  
SOME SPECIFICS OF THIS SYSTEM WILL BE SENSITIVE TO ITS SPEED AND  
LONGITUDE AS IT REACHES NEAR FLORIDA AND TIMING OF THE EXPECTED  
WEAKENING OF THE EASTERN U.S. UPPER TROUGH. EXPECT THE GREAT  
LAKES REGION TO SEE SOME RAINFALL WITH THE CHILLY CYCLONIC FLOW IN  
PLACE DURING THE FIRST HALF OF THE WEEK, WHILE THE NORTHWEST MAY  
SEE MOSTLY LIGHT RAINFALL AROUND MIDWEEK WITH THE FOUR CORNERS  
STATES ALSO SEEING SOME POTENTIAL FOR SCATTERED RAINFALL.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE LATEST RUN OF THE GFS CONTINUES TO FAVOR A MORE WESTERN,  
SLOWER TRACK OF TROPICAL DEPRESSION NINE THAT WOULD RESULT IN  
DOUBLE DIGIT RAINFALL THAT'S ROUGHLY 10+ INCHES HEAVER THAN THE  
REST OF THE GUIDANCE WITH MORE IMPACTS TO THE WESTERN PART OF THE  
FLORIDA PENINSULA. THE UKMET AND CMC ARE MORE OF A MIDDLE GROUND  
APPROACH BUT LEAN CLOSER TO THE ECWMF SOLUTION THAT IS FASTER,  
CLIPS FLORIDA AND THEN RACES OUT OVER THE ATLANTIC QUICKLY NEAR  
THE ADVANCING FRONT. IT ALSO SUGGESTS THAT THE NORTHERN  
STREAM/TROUGH OVER THE EAST WILL HELP MOVE THE TROPICAL FEATURE  
ALONG INSTEAD OF CUTTING OFF/SPINNING TO ITS DEATH. THE NHC'S  
TRACK IS FAVORING AN EVOLUTION CLOSER TO THAT OF THE ECWMF.  
THEREFORE THE WPC'S BLEND INITIALLY WAS A MULTI-MODEL BLEND WITH  
LESSER WEIGHTING OF THE GFS AND THEN TRANSITIONED TOWARD AN  
ECWMF/GFS/GEFS AND EC ENSEMBLE MEANS COMPROMISE.  
 
THERE IS STILL MODERATE SPREAD WITH THE DETAILS OF THE EASTERN  
TROUGH BEYOND THOSE NOTED FROM THE 12Z ECMWF. RUN-TO-RUN  
VARIABILITY PERSISTS WITH THE TIMING OF THE TROUGH PUSHING INLAND  
THE PACIFIC NORTHWEST, BUT IS FAIRLY COMMON FOR THAT TIME FRAME  
BUT DIVERGE IN THE LATER PERIODS WHERE TROUGHING REMAINS OR IF  
RIDGING TRIES TO REBUILD.  
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE DOMINANT RAINFALL THREAT DURING THE PERIOD WILL BE WITH  
TROPICAL CYCLONE NINE THAT MAY AFFECT FLORIDA AND POTENTIALLY  
OTHER PARTS OF THE SOUTHEAST/EAST COAST. A FRONT EXPECTED TO  
STALL OVER FLORIDA BEFORE ARRIVAL OF THE SYSTEM COULD PROVIDE AN  
ADDED FOCUS FOR RAINFALL. NOTE THAT THERE IS STILL CONSIDERABLE  
UNCERTAINTY REGARDING THE ULTIMATE TRACK OF THIS SYSTEM BY THE  
LATTER HALF OF THE WEEK. HOWEVER INTO EARLY WEDNESDAY THERE IS  
SUFFICIENT POTENTIAL FOR HEAVY RAINFALL TO INTRODUCE A SLIGHT RISK  
AREA ON THE EXPERIMENTAL DAY 5 EXCESSIVE RAINFALL OUTLOOK OVER  
PARTS OF THE FLORIDA PENINSULA. CONTINUE TO MONITOR NATIONAL  
HURRICANE CENTER PRODUCTS FOR THE LATEST INFORMATION REGARDING  
THIS SYSTEM.  
 
EXPECT THE GREAT LAKES AND VICINITY TO SEE PERIODS OF RAIN THROUGH  
THE FIRST HALF OF THE WEEK WITH CHILLY AND BRISK CYCLONIC FLOW IN  
PLACE AT LOW LEVELS AND THE UPPER TROUGH OVERHEAD. A FEW FOCUSED  
BANDS TO THE LEE OF THE GREAT LAKES COULD PRODUCE SOME ENHANCED  
TOTALS. THE PACIFIC NORTHWEST SHOULD SEE A PERIOD OF LIGHT TO  
PERHAPS ISOLATED MODERATE RAINFALL AROUND MIDWEEK WITH THE FRONTAL  
SYSTEM FORECAST TO PUSH INTO THE REGION. SCATTERED RAIN OVER  
PORTIONS OF THE FOUR CORNERS STATES MAY GRADUALLY INCREASE IN  
COVERAGE OVER THE COURSE OF THE WEEK.  
 
THE EVOLUTION OF THE UPPER PATTERN WILL FAVOR CHILLY TEMPERATURES  
OVER A MAJORITY OF THE EASTERN U.S. WITH BEST POTENTIAL FOR HIGHS  
UP TO 10-15F BELOW NORMAL OVER AND NEAR THE GREAT LAKES/OHIO  
VALLEY, ESPECIALLY TUESDAY-THURSDAY. MEANWHILE THE WEST WILL BE  
ON THE WARM SIDE MONDAY-WEDNESDAY WITH SOME AREAS FROM THE  
NORTHWEST INTO NORTHERN ROCKIES LIKELY SEEING HIGHS UP TO 10-15F  
ABOVE NORMAL, FOLLOWED BY A COOLER TREND CLOSER TO NORMAL LATER IN  
THE WEEK AS THE WARM AIR REACHES THE HIGH PLAINS.  
 
CAMPBELL/RAUSCH  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, MON-THU, SEP 26-SEP  
29.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, TUE-THU, SEP 27-SEP  
29.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST.  
- HIGH WINDS ACROSS PORTIONS OF THE SOUTHEAST, MON-WED, SEP 26-SEP  
28.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PANHANDLE AND  
MAINLAND ALASKA, MON-TUE, SEP  
26-SEP 27AND THU-FRI, SEP 29-SEP 30.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF MAINLAND ALASKA, WED-THU,  
SEP 28-SEP 29.  
 
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES ARE  
AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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