267  
FXUS02 KWBC 201909  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
308 PM EDT SUN MAR 20 2022  
 
VALID 12Z WED MAR 23 2022 - 12Z SUN MAR 27 2022  
 
...A LOW PRESSURE SYSTEM WILL LIKLEY SPREAD MODERATE TO HEAVY RAIN  
THROUGH THE EASTERN U.S. MIDWEEK, WITH SEVERE STORMS POSSIBLE IN  
THE SOUTHEAST, AND WINTRY WEATHER ACROSS THE NORTHERN TIER...  
 
   
..OVERVIEW
 
 
ACTIVE WEATHER WILL LIKELY REACH THE EASTERN U.S. BY WEDNESDAY  
WITH A TENDENCY OF DECREASING RAIN INTENSITY AS A LARGE OCCLUDED  
CYCLONE SHOULD GRADUALLY WEAKEN AND MOVE ACROSS THE REGION LATE  
THIS WEEK, WITH INITIAL THREAT OF SEVERE THUNDERSTORMS AHEAD OF  
THE COLD FRONT IN THE SOUTHEAST. MEANWHILE ON THE COLD NORTHERN  
SIDE OF THE SYSTEM, SPRINGTIME SNOW AND MIXED PRECIPITATION ARE  
POSSIBLE FROM THE GREAT LAKES REGION TO THE INTERIOR NORTHEAST.  
AS A RIDGE BUILDS INTO THE WEST, POSSIBLE RECORD HIGH TEMPERATURES  
ACROSS CALIFORNIA WILL BE CONTRASTED WITH A COOLING TREND IN THE  
GREAT LAKES TO THE NORTHEAST WHERE AN UPPER TROUGH IS FORECAST TO  
AMPLIFY. THIS INCREASE IN AMPLITUDE OF THE UPPER-LEVEL PATTERN  
ACROSS THE U.S. BY NEXT WEEKEND WOULD INTRODUCE HIGHER UNCERTAINTY  
AND THUS LOWER PREDICTABILITY PARTICULARLY ACROSS THE NORTHEAST  
AND JUST OFF THE WEST COAST.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE MEDIUM-RANGE PERIOD WILL BEGIN ON WEDNESDAY AS AN OCCLUDED  
CYCLONE WILL LIKELY BE NEAR PEAK INTENSITY AS THE CYCLONE CENTER  
TRACKS ACROSS THE MIDWEST. MODEL GUIDANCE/CONSENSUS CONTINUES  
WITH A SUBTLE TREND OF WRAPPING ADDITIONAL PRECIPITATION AROUND  
THE NORTHERN SIDE OF THE CYCLONE ACROSS THE UPPER MIDWEST TOWARD  
THE NORTHERN PLAINS, WHILE RAIN AND THUNDERSTORMS AHEAD OF THE  
TRAILING COLD FRONT WERE NUDGED PROGRESSIVELY FASTER THROUGH THE  
EASTERN U.S. THIS TREND IS DUE TO A GRADUAL AMPLIFICATION OF THE  
UPPER TROUGH BEHIND THE CYCLONE ACROSS THE PLAINS STATES IN THE  
MODEL GUIDANCE, LEADING TO A GRADUAL TREND FOR THE CYCLONE TO  
EVOLVE INTO A CLASSICAL OCCLUSION. THE CMC REMAINS TO BE THE MORE  
ENTHUSIASTIC GUIDANCE IN THIS REGARD, THOUGH WITH NOTICEABLE  
RUN-TO-RUN VARIABILITY, AND THUS HAS BEEN THE SLOWEST GUIDANCE IN  
PULLING THE SYSTEM OUT OF THE NORTHWEST LATE THIS WEEK. THE GFS  
AND ECMWF ARE MOSTLY IN AGREEMENT WITH ONE ANOTHER, AND NOT AS  
SLOW AS THE CMC REGARDING THIS SYSTEM.  
 
TOWARD NEXT WEEKEND, MODELS ARE GENERALLY INDICATING A TREND  
TOWARD AN INCREASINGLY AMPLIFIED PATTERN ACROSS THE U.S. AS A  
RIDGE IS FORECAST TO BUILD OVER THE WEST WHILE UPPER-LEVEL  
SHORTWAVES ARE PREDICTED TO DIG SOUTHEASTWARD FROM CENTRAL CANADA  
TOWARD THE NORTHEASTERN U.S. THIS INCREASE IN AMPLITUDE OF THE  
UPPER-LEVEL PATTERN WOULD TEND TO INTRODUCE HIGHER UNCERTAINTY AND  
THUS LOWER PREDICTABILITY PARTICULARLY ACROSS THE NORTHEAST AND  
JUST OFF THE WEST COAST WHERE ANOTHER AMPLIFIED TROUGH IN THE  
PACIFIC APPEARS TO EDGE CLOSER. BOTH THE EC AND GFS BEGIN TO  
DIVERGE FROM THEIR CORRESPONDING ENSEMBLE MEANS BY LATE WEEK,  
WHICH IMPLIES HIGHER UNCERTAINTY WITH THE PATTERN.  
 
THEREFORE, THE WPC MEDIUM-RANGE PACKAGED WAS BASED MAINLY ON THE  
CONSENSUS OF THE 00Z ECMWF/EC MEAN AND THE 06Z GFS/GEFS MEAN, WITH  
INCREASING USAGE OF THE ENSEMBLE MEANS TOWARD THE WEEKEND. A  
SMALL CONTRIBUTION OF THE 00Z CMC WAS INCLUDED FOR DAYS 3-4  
FOLLOWED BY A SMALL AMOUNT FROM THE CMC MEAN DAYS 5-7. THE  
RESULTS ARE REASONABLY COMPATIBLE WITH WPC CONTINUITY.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
ANOTHER RAINY DAY IS EXPECTED AS THE MEDIUM RANGE PERIOD BEGINS  
WEDNESDAY AS GULF OF MEXICO MOISTURE AHEAD OF THE LOW PRESSURE  
SYSTEM TRACKING ACROSS THE CENTRAL U.S. WILL LIKELY BEGIN TRENDING  
DOWNWARD THEREAFTER. STORMS COULD BE SEVERE ACROSS THE DEEP SOUTH  
DOWN TO THE CENTRAL/EASTERN GULF COAST PER THE STORM PREDICTION  
CENTER. FURTHERMORE, WIDESPREAD RAIN IS LIKELY ACROSS THE EAST,  
WHICH COULD POTENTIALLY CAUSE SOME ISOLATED FLASH FLOODING IN SOME  
AREAS FROM THE SOUTHERN/CENTRAL APPALACHIANS EASTWARD. NORTH AND  
WEST OF THE LOW TRACK, SNOW AND WINTRY PRECIPITATION ARE POSSIBLE,  
WITH THE HIGHEST PROBABILITIES FOR NOTABLE SNOW IN THE UPPER GREAT  
LAKES REGION. WINTRY MIX OR SNOW COULD ALSO OCCUR PARTICULARLY IN  
HIGHER ELEVATIONS OF THE INTERIOR NORTHEAST NORTH OF A WARM FRONT  
ON WEDNESDAY-THURSDAY AND AS A WESTERN ATLANTIC LOW DEVELOPS BY  
EARLY FRIDAY. SHOWERS COULD LINGER INTO LATE WEEK ACROSS THE EAST  
WITH GENERALLY LIGHT AMOUNTS EXPECTED, BUT PERHAPS WITH MORE  
MODERATE AMOUNTS AS A FRONT LINGERS IN FLORIDA, WHICH COULD CAUSE  
LOCALIZED FLOODING ISSUES IF RAIN FALLS ATOP SATURATED SOILS. A  
MAINLY DRY PATTERN IS EXPECTED FOR THE WESTERN AND CENTRAL U.S.  
FOR THE LATTER PART OF THE WEEK, THOUGH WITH SOME PACIFIC  
NORTHWEST AND NORTHERN ROCKIES LIGHT PRECIPITATION POSSIBLE BEFORE  
A MORE WIDESPREAD MOISTURE SURGE NEXT WEEKEND.  
 
THE STRONG UPPER RIDGE BUILDING INTO THE WEST WILL LEAD TO A BROAD  
AREA OF HIGHS 10-20F ABOVE NORMAL WEDNESDAY-SUNDAY WITH SLIGHTLY  
HIGHER LOCALIZED ANOMALIES POSSIBLE. THERE IS POTENTIAL TO REACH  
DAILY RECORD HIGHS ACROSS CALIFORNIA WEDNESDAY TO FRIDAY AND  
SPREADING EASTWARD INTO THE INTERMOUNTAIN WEST AND SOUTHWEST AS  
THE RIDGE AXIS SHIFTS EAST. LEADING UPPER LEVEL TROUGHING SHOULD  
SUPPORT TEMPERATURES 10-20F BELOW AVERAGE ACROSS THE  
CENTRAL/SOUTHERN HIGH PLAINS WEDNESDAY. THE COOLER AIR SHOULD  
MODERATE CLOSER TO NORMAL BY THE LATTER PART OF NEXT WEEK AS IT  
PROGRESSES EASTWARD. AHEAD OF THE TROUGH AND COLD FRONTS,  
GENERALLY WARMER THAN NORMAL CONDITIONS ARE LIKELY ACROSS MUCH OF  
THE EASTERN THIRD OF THE U.S. FOR MUCH OF THE WEEK, TRANSITIONING  
TO NEAR NORMAL TEMPERATURES BY FRIDAY AND SATURDAY AND A COOLDOWN  
ASSOCIATED WITH A SECONDARY COLD FRONT IN THE GREAT LAKES BY  
SUNDAY. ISOLATED RECORD HIGHS ARE POSSIBLE OVER PARTS OF FLORIDA  
TUESDAY-WEDNESDAY.  
 
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  
 
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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