304  
FXUS02 KWBC 190643  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
242 AM EDT MON SEP 19 2022  
 
VALID 12Z THU SEP 22 2022 - 12Z MON SEP 26 2022  
 
...HEAVY RAINFALL THREAT LINGERS FOR THE FOUR CORNERS/ROCKIES INTO  
THURSDAY...  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
LATEST MODEL AND ENSEMBLE SOLUTIONS SEEM PRETTY WELL CLUSTERED  
THROUGH MEDIUM RANGE TIME SCALES OVER THE LOWER 48, BOLSTERING  
FORECAST CONFIDENCE DESPITE SOME LINGERING LOCAL EMBEDDED SYSTEM  
TIMING/STRENGTH DIFFERENCES. THE WPC MEDIUM RANGE PRODUCT SUITE  
WAS PRIMARILY DERIVED FROM A COMPOSITE OF THE 18 UTC GFS AND 12  
UTC ECMWF/UKMET ALONG WITH THE 01 UTC NATIONAL BLEND OF MODELS  
(NBM) THURSDAY-SATURDAY BEFORE SWITCHING MAINLY TO THE 18 UTC  
GEFS/12 UTC ECMWF ENSEMBLE MEANS AND 01 UTC NBM AT LONGER TIME  
FRAMES INTO SUNDAY/NEXT MONDAY. GUIDANCE DIFFERENCES SEEM WELL  
MITIGATED BY THE BLENDING PROCESS CONSISTENT WITH PREDICTABILITY.  
WPC PRODUCT CONTINUITY IS WELL MAINTAINED IN THIS MANNER AND NEWER  
00 UTC MODEL AND ENSEMBLE GUIDANCE GENERALLY REMAINS IN LINE.  
   
..PATTERN OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
 
 
THE SLOW EJECTION OF AN AMPLIFIED UPPER TROUGH/LOW AND FRONTAL  
SYSTEM THROUGH THE NORTH-CENTRAL GREAT BASIN/ROCKIES THURSDAY INTO  
FRIDAY FAVORS COOLER TEMPERATURES THAT MAY LEAD TO SOME SNOW FOR  
HIGH ELEVATIONS. MAXIMUM DAILY TEMPERATURES ARE FORECAST TO  
TEMPORARILY DIP 10 TO 15 DEGREES F BELOW AVERAGE. ANOMALOUS  
MOISTURE LIFTED ACROSS THE FOUR CORNERS REGION IN ADVANCE OF THE  
EJECTING UPPER TROUGH WILL INCREASE CHANCES FOR MODERATE TO  
LOCALLY HEAVIER RAINFALL/THUNDERSTORMS. THERE REMAINS A SLIGHT  
RISK AREAS ON THE DAY 4 EXPERIMENTAL WPC EXCESSIVE RAINFALL  
OUTLOOK ACROSS THE FOUR CORNERS REGION. ADDITIONAL ACTIVITY WILL  
WORK ACROSS NORTHERN GREAT BASIN/ROCKIES THURSDAY TO THE  
NORTH-CENTRAL U.S. AND INTO THE EAST FRIDAY INTO THE WEEKEND GIVEN  
FAVORABLE UPPER SYSTEM SUPPORT AND WELL DEFINED COLD FRONT.  
 
AN ERODING LEAD UPPER RIDGE OVER THE SOUTH WILL SUPPORT LINGERING  
10-15F WARMER THAN AVERAGE TEMPERATURES INTO THURSDAY. THIS WILL  
BE IN ADVANCE OF THE AFOREMENTIONED COLD FRONT. HEAT WILL QUICKLY  
GET SUPPRESSED WITH THIS FRONTAL PASSAGE AS QUITE COOLED CANADIAN  
POST-FRONTAL HIGH PRESSURE SETTLES INTO THE CENTRAL TO EASTERN  
U.S.. THE LINGERING FRONT MAY FOCUS SOME SHOWERS ACROSS FLORIDA  
THROUGH THE WEEKEND.  
 
SCHICHTEL  
 
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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