529  
FXUS02 KWBC 241903  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
302 PM EDT SUN APR 24 2022  
 
VALID 12Z WED APR 27 2022 - 12Z SUN MAY 01 2022  
   
..OVERVIEW
 
 
MODEST CYCLOGENESIS NEAR/EAST OF NEW ENGLAND MIDWEEK IS FORECAST  
TO BRING LINGERING MIXED PRECIPITATION AND GUSTY WINDS LATE THIS  
WEEK INTO NEXT WEEKEND FOR PARTS OF THE NORTHEAST. MEANWHILE,  
MULTIPLE SHORTWAVES MOVING ONSHORE INTO THE PACIFIC NORTHWEST WILL  
LIKELY PUSH A BROAD TROUGH THROUGH MUCH OF THE WESTERN U.S. LATE  
THIS WEEK, REACHING INTO THE NORTHERN/CENTRAL PLAINS BY THE  
WEEKEND WHERE A LOW PRESSURE SYSTEM IS FORECAST TO FORM. A BROAD  
SHIELD OF PRECIPITATION AHEAD OF THIS SYSTEM IS FORECAST TO EXPAND  
ACROSS THE MIDSECTION OF THE COUNTRY INTO THE OHIO AND TENNESSEE  
VALLEYS AND THEN TOWARD APPALACHIANS BY NEXT WEEKEND, ALTHOUGH  
DETAILS REMAIN UNCERTAIN AT THIS POINT.  
 
   
..MODEL GUIDANCE EVALUATION
 
 
MODEL GUIDANCE REMAINS QUITE AGREEABLE IN KEEPING A SLOW-MOVING  
LOW PRESSURE SYSTEM OVER THE CANADIAN MARITIMES THROUGH MUCH OF  
THE MEDIUM-RANGE PERIOD AFTER MODEST CYCLOGENESIS IS FORECAST TO  
OCCUR NEAR/EAST OF NEW ENGLAND ON WEDNESDAY. THERE IS ALSO GOOD  
AGREEMENT ON THE BROAD RIDGE OVER THE CENTRAL U.S., THOUGH WITH  
UNCERTAIN DETAILS ON EMBEDDED SHORTWAVES. IN CONTRAST, MODELS  
CONTINUE TO INDICATE MUCH UNCERTAINTY WITH MULTIPLE SHORTWAVES  
FORECAST TO MOVE ONSHORE ACROSS THE PACIFIC NORTHWEST, LEADING TO  
DIVERGING MODEL SOLUTIONS BY NEXT WEEKEND AS THE SYSTEM REACHES  
INTO THE MIDSECTION OF THE COUNTRY. WHILE THERE HAS BEEN A WIDE  
VARIETIES OF POSSIBLE OUTCOMES AS SHOWN BY RECENT DETERMINISTIC  
MODEL SOLUTIONS, ENSEMBLE MEANS HAVE GENERALLY AGREED TO DEVELOP  
AND CONSOLIDATE A BROAD LOW PRESSURE SYSTEM TO BE CENTERED OVER  
THE CENTRAL PLAINS ON SATURDAY, AND HEADING GENERALLY TOWARD THE  
EAST OR EAST-NORTHEAST, WITH A BROAD SWATH OF PRECIPITATION AHEAD  
OF THE ENTIRE SYSTEM. THIS MULTI-MODEL/ENSEMBLE APPROACH YIELDED  
A SOLUTION THAT IS QUITE COMPATIBLE WITH THE PREVIOUS WPC  
MEDIUM-RANGE FORECAST PACKAGE. TOWARD THE END OF THE FORECAST  
PERIOD, THE GFS AND GEFS HAVE GENERALLY SLOWED DOWN THE EASTWARD  
PROGRESSION OF THE CENTRAL U.S. SYSTEM IN BETTER AGREEMENT WITH  
THE ECMWF AND CMC MEANS. THEREFORE, A SLOWER SOLUTION IS  
PREFERRED.  
 
THE WPC MEDIUM-RANGE MORNING PACKAGE BEGINS WITH A BLEND OF 40%  
FROM THE 00Z ECMWF/00Z EC MEAN, 40% FROM THE 06Z GFS/GEFS, AND 20%  
FROM THE 00Z CMC/CMC MEAN, TRANSITIONING TO A BLEND OF 45% FROM  
THE 00Z EC/EC MEAN, 30% FROM THE 06Z GEFS AND 25% FROM THE CMC  
MEAN BY DAY 7.  
 
   
..SENSIBLE WEATHER/THREATS
 
 
THE NORTHEASTERN U.S. COULD RECEIVE MULTIPLE ROUNDS OF  
PRECIPITATION THROUGH MUCH OF THE WEEK AS THE UPPER LEVEL AND  
SURFACE LOWS PIVOT AND LINGER OVER THE AREA. PERIODS OF  
PRECIPITATION SHOULD GENERALLY BE LIGHT TO MODERATE; AMOUNTS WILL  
ADD UP OVER TIME BUT STILL ARE NOT EXPECTED TO BE TOO HAZARDOUS.  
HIGHER ELEVATIONS OF NEW ENGLAND MAY SEE SNOW DURING THE NIGHT BUT  
MIXING WITH RAIN DURING THE DAY. SOME RAIN MAY BEGIN IN THE  
CENTRAL U.S. AS EARLY AS WEDNESDAY NEAR A WARM FRONT AND SURFACE  
LOW, BUT RAIN IS LIKELY TO INCREASE IN COVERAGE AND AMOUNTS AS THE  
WEEK PROGRESSES AS THE MAIN UPPER TROUGH EXITS THE ROCKIES AND  
CONSOLIDATES A LOW PRESSURE A LOW PRESSURE SYSTEM IN THE CENTRAL  
U.S. THE ENTIRE SYSTEM IS FORECAST TO PUSH EASTWARD TOWARD THE  
EASTERN U.S. LATER NEXT WEEKEND. UNSETTLED WEATHER SHOULD ALSO  
OCCUR IN THE WESTERN TO NORTH-CENTRAL U.S., WITH AMOUNTS  
INCREASING FROM THURSDAY INTO FRIDAY AND BEGINS TO LESSEN BY NEXT  
WEEKEND. CONDITIONS WILL LIKELY BE COLD ENOUGH FOR SNOW IN THE  
NORTHERN ROCKIES ON THE BACKSIDE OF THE SURFACE LOW, AND THERE IS  
ONCE AGAIN SOME THREAT OF WINTRY PRECIPITATION SPREADING INTO THE  
NORTHERN HIGH PLAINS AS WELL. BUT THE FULL DETAILS OF THESE  
THREATS MAY NOT REALIZED FOR A FEW MORE DAYS GIVEN THE CURRENT  
MODEL UNCERTAINTY.  
 
COOLER THAN AVERAGE TEMPERATURES ARE IN STORE FOR THE EASTERN  
THIRD OF THE U.S. WEDNESDAY INTO THURSDAY, WITH THE CORE OF THE  
COLD AIR MOVING THROUGH THE GREAT LAKES/CENTRAL APPALACHIANS,  
WHERE TEMPERATURES 10-20F BELOW NORMAL WILL MAKE FOR THE  
POSSIBILITY OF A FEW DAILY RECORD LOWS ON WEDNESDAY. ON THE OTHER  
HAND WARMER THAN NORMAL TEMPERATURES SHOULD SPREAD FROM THE  
SOUTHWEST/FOUR CORNERS STATES INTO SOUTHERN AND CENTRAL PARTS OF  
THE PLAINS UNDERNEATH UPPER RIDGING. BY FRIDAY INTO THE WEEKEND,  
THE PATTERN SHOULD GENERALLY SHIFT TO COOLER THAN AVERAGE  
TEMPERATURES IN THE NORTH AND WARMER THAN AVERAGE IN THE SOUTH.  
THE NORTHERN PLAINS TO MIDWEST ARE FORECAST TO SEE HIGHS NEARING  
20F BELOW AVERAGE, BUT LOWS MAY BE CLOSER TO NORMAL. MEANWHILE,  
THE SOUTHERN TIER SHOULD BE AROUND 10F ABOVE AVERAGE.  
 
KONG/TATE  
 
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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