339  
FXUS02 KWBC 300705  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
204 AM EST SUN JAN 30 2022  
 
VALID 12Z WED FEB 02 2022 - 12Z SUN FEB 06 2022  
 
...HEAVY PRECIPITATION LIKELY TO IMPACT THE CENTRAL AND EASTERN  
U.S. LATER THIS WEEK, INCLUDING A WINTER STORM FROM THE CENTRAL  
PLAINS TO GREAT LAKES AND INTERIOR NORTHEAST...  
 
   
..OVERVIEW
 
 
MEAN TROUGHING SHOULD DOMINATE MUCH OF THE CONUS EAST OF THE  
ROCKIES AS STRONG UPPER RIDGING BUILDS OVER BOTH THE WESTERN  
ATLANTIC AND EAST PACIFIC. A SHORTWAVE INITIALLY OVER THE  
SOUTHWEST ON WEDNESDAY WILL DRIVE A POTENT COLD FRONT EASTWARD  
THROUGH FRIDAY BRINGING WIDESPREAD HEAVY RAIN TO THE SOUTH AND A  
POTENTIALLY SIGNIFICANT WINTER STORM FROM THE MID-MISSISSIPPI  
VALLEY TO THE INTERIOR NORTHEAST. ADDITIONAL WAVES OF SHORTWAVE  
ENERGY DROPPING DOWN THE EAST SIDE OF THE RIDGE IN THE WEST,  
SHOULD HELP REINFORCE MEAN TROUGHING ACROSS THE CENTRAL U.S.  
THROUGH NEXT WEEKEND.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
GUIDANCE HAS COME INTO OVERALL GOOD AGREEMENT REGARDING AN  
AMPLIFIED SHORTWAVE INITIALLY ACROSS THE SOUTHWEST ON WEDNESDAY  
AND INTO THE SOUTHERN PLAINS/MID-SOUTH THURSDAY-FRIDAY. THERE  
REMAIN SOME MINOR DIFFERENCES IN THE SHORTWAVE TIMING (ECMWF HAS  
BEEN CONSISTENTLY SLIGHTLY FASTER THAN THE GFS), WHICH ULTIMATELY  
AFFECTS FRONTAL TIMING, ESPECIALLY INTO THE EAST. ALBEIT  
DIFFERENCES IN TIMING AND PLACEMENT, GUIDANCE SHOWS THIS ENERGY  
MAY ULTIMATELY COMBINE WITH A NORTHERN STREAM SHORTWAVE THROUGH  
THE GREAT LAKES/NORTHEAST LATE THIS WEEK TO HELP INDUCE A  
DEEPENING SURFACE LOW WELL OFF THE NORTHEAST COAST. GIVEN THE  
OVERALL AGREEMENT, A GENERAL MODEL COMPROMISE BETWEEN THE LATEST  
RUNS OF THE DETERMINISTIC MODELS SEEMED A GOOD STARTING POINT FOR  
NOW THROUGH DAY 5 FOR THIS SYSTEM WHICH ALSO MAINTAINED GOOD  
CONTINUITY WITH THE .  
 
NEXT ENERGY DROPS INTO THE MEAN TROUGH OUT OF THE WEST BY FRIDAY  
AND THE MODELS CONTINUE TO STRUGGLE BOTH WITH STRENGTH AND TIMING  
OF THE SHORTWAVE. RECENT MODEL RUNS HAVE BEEN BACK AND FORTH  
BETWEEN A WEAKER/FASTER SHORTWAVE AND A STRONGER/SLOWER POSSIBLE  
CLOSED LOW LINGERING OVER THE SOUTHWEST FOR A DAY OR TWO. AT LEAST  
THROUGH THE LATEST 12Z/18Z (YESTERDAY) GUIDANCE, THE ECMWF AND CMC  
ARE WEAKER AND FASTER WHILE THE 18Z GFS IS NOTABLY MORE  
AMPLIFIED/SLOWER. THE BULK OF THE ENSEMBLE GUIDANCE WOULD SUPPORT  
SOMETHING MORE TOWARDS THE QUICKER ECMWF/CMC SO THAT'S THE WAY THE  
WPC FORECAST LEANED TONIGHT.  
 
YET ANOTHER SHORTWAVE ROUNDING THE TOP OF THE RIDGE DROPS INTO THE  
NORTHERN ROCKIES BY SATURDAY. MUCH OF THE GUIDANCE SHOWS THE  
SHORTWAVE PROGRESS RATHER HARMLESSLY SOUTH AND EASTWARD INTO THE  
NORTHERN/CENTRAL PLAINS ON SUNDAY, BUT THE LAST FEW RUNS OF THE  
GFS HAVE BEEN QUITE AGGRESSIVE WITH DEEPENING THIS ENERGY AND A  
CLOSED LOW FORMING OVER THE SOUTHWEST. ENSEMBLE PLOTS SUGGEST THE  
GFS IS LIKELY MUCH TOO DEEP WITH THIS, AND THE ACTUAL SOLUTION MAY  
BE SOMEWHERE IN THE MIDDLE OF A SIGNIFICANTLY WEAKER/FASTER ECMWF  
AND THE GFS (SIMILAR TO THE 12Z CMC). THE BEST COURSE OF ACTION  
FOR THE WPC FORECAST FOR NEXT WEEKEND WAS TO STAY CLOSE TO THE  
ENSEMBLE MEANS, WITH LESSER INFLUENCE FROM THE CMC AND ECMWF JUST  
FOR SOME ADDED SYSTEM DEFINITION ACROSS THE BOARD.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
THE DEEPENING TROUGH IN THE WEST WILL INITIALLY BRING LIGHT TO  
MODERATE PRECIPITATION ACROSS THE CENTRAL/SOUTHERN ROCKIES AND THE  
FOUR CORNERS REGION ON WEDNESDAY. AHEAD OF THIS, AMPLE GULF  
MOISTURE WILL BE DRAWN NORTHWARD AHEAD OF THE TROUGH AND  
ASSOCIATED SURFACE COLD FRONT. THIS SHOULD RESULT IN WIDESPREAD  
MODERATE TO HEAVY PRECIPITATION FROM THE SOUTHERN PLAINS INTO THE  
NORTHEAST WEDNESDAY AND THURSDAY. THE BEST CHANCE FOR HEAVY  
RAINFALL EXTENDS FROM THE SOUTHERN PLAINS AND LOWER MISSISSIPPI  
VALLEY INTO PARTS OF THE LOWER OHIO/TENNESSEE VALLEYS TO THE  
APPALACHIANS AND THE EAST. THE OVERALL PATTERN WOULD CERTAINLY  
SUPPORT AT LEAST LOCAL SPOTS EXCESSIVE RAINFALL/FLASH FLOODING,  
BUT THE EXACT LOCATIONS REMAIN QUITE UNCERTAIN AND DEPENDENT ON  
SMALLER SCALE DETAIL DIFFERENCES, AND IMPEDED BY AN OVERALL LACK  
OF INSTABILITY.  
 
POSSIBLY THE BIGGER THREAT HOWEVER IS THE INCREASING POTENTIAL FOR  
A SIGNIFICANT WINTER STORM ON THE BACKSIDE OF THIS SYSTEM FROM THE  
CENTRAL PLAINS INTO THE MIDWEST/LOWER GREAT LAKES AND EVENTUALLY  
THE INTERIOR NORTHEAST. HEAVY ACCUMULATING SNOW IS LIKELY, WHILE  
POSSIBLE IMPACTFUL SLEET AND FREEZING RAIN JUST TO THE SOUTH  
WITHIN THE TRANSITION ZONE BETWEEN THE RAIN TO THE SOUTH AND SNOW  
TO THE NORTH. EXACT AMOUNTS OF ANY WINTRY PRECIPITATION REMAIN IN  
FLUX AT THIS POINT AND HIGHLY DEPENDENT ON THE LOWER-CONFIDENCE  
DETAILS OF EJECTING SHORTWAVE ENERGY, FRONTAL WAVES, AND TIMING OF  
COLDER TEMPERATURES.  
 
ABOVE AVERAGE TEMPERATURES (GENERALLY +10-15F) WILL SPREAD ACROSS  
THE EAST WEDNESDAY-THURSDAY. MEANWHILE, AS ARCTIC HIGH PRESSURE  
DIVES INTO THE CENTRAL U.S. BEHIND THE COLD FRONT MIDWEEK,  
DOWNRIGHT CHILLY AND MUCH BELOW NORMAL TEMPERATURES WILL SPREAD  
FROM THE NORTHERN ROCKIES/HIGH PLAINS ALL THE WAY AS FAR SOUTH AS  
TEXAS. WIDESPREAD DAYTIME HIGHS (AND SLIGHTLY LESS EXTREME  
OVERNIGHT LOWS) AS MUCH AS 10-25 DEGREES BELOW AVERAGE ARE LIKELY  
WITH SOME LOCALLY HIGHER SPOTS ESPECIALLY THURSDAY ACROSS PARTS OF  
OKLAHOMA AND NORTH/CENTRAL TEXAS. THESE TEMPERATURES MAY MODERATE  
SLIGHTLY AS THEY SHIFT EAST INTO THE OHIO VALLEY/GULF COAST STATES  
NEXT FRIDAY AND THE EAST ON SATURDAY, THOUGH TEXAS REMAINS BELOW  
AVERAGE THROUGH THE END OF THE WEEK. THE WEST COAST STATES SHOULD  
BE NEAR NORMAL THROUGH MUCH OF NEXT WEEK OWING TO AMPLIFIED  
RIDGING ACROSS THE EAST PACIFIC.  
 
SANTORELLI  
 
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, 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/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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