626  
FXUS02 KWBC 031908  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
207 PM EST THU MAR 03 2022  
 
VALID 12Z SUN MAR 06 2022 - 12Z THU MAR 10 2022  
 
...HEAVY RAIN POTENTIAL ACROSS THE MID-MISSISSIPPI VALLEY INTO  
OHIO VALLEY SUNDAY INTO MONDAY...  
   
..OVERVIEW
 
 
THE MEDIUM RANGE PERIOD WILL BEGIN SUNDAY WITH A SHORTWAVE AND  
SURFACE LOW PRESSURE SYSTEM OVER THE GREAT LAKES, BRINGING  
LINGERING SNOW THERE, BUT MORE SIGNIFICANTLY A CHANCE FOR HEAVY TO  
EXCESSIVE RAINFALL ALONG ITS ASSOCIATED COLD FRONT, SPREADING FROM  
THE MID-MISSISSIPPI VALLEY INTO THE OHIO VALLEY FOR THE EARLY PART  
OF THE WEEK. FARTHER WEST, PERSISTENT TROUGHING WILL BE IN PLACE  
IN BETWEEN A RIDGE IN THE EAST PACIFIC AND A SUBTROPICAL HIGH  
INITIALLY IN THE GULF OF MEXICO. BROAD TROUGHING SHOULD SPREAD  
EASTWARD ACROSS THE LOWER 48 AS THE WEEK PROGRESSES AS THE  
SUBTROPICAL HIGH GETS PUSHED SOUTH INTO THE CARIBBEAN SEA.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
RECENT MODEL GUIDANCE BEGINS THE MEDIUM RANGE PERIOD IN RATHER  
GOOD AGREEMENT FOR THE LARGE SCALE PATTERN AND EVEN WITH PLACEMENT  
OF INITIAL SHORTWAVES, INCLUDING THE IMPACTFUL ONE IN THE GREAT  
LAKES AND A LIKELY CLOSED LOW IN THE FOUR CORNERS EMBEDDED IN THE  
WEST TROUGH. AT THE SURFACE, GOOD CONSENSUS EXISTS THAT THE  
SURFACE LOW IN THE GREAT LAKES SUNDAY MORNING WILL TRACK QUICKLY  
NORTHEASTWARD, WHILE A SECONDARY LOW FORMS ALONG THE TRAILING COLD  
FRONT BY MONDAY. THERE HAVE BEEN MORE MODEL VARIATIONS WITH THE  
PLACEMENT OF THIS WAVE WITHIN AN ELONGATED AREA OF LOW PRESSURE,  
BUT MODELS SEEM TO BE COMING TO A CONSENSUS OVER THE OHIO VALLEY  
MONDAY MORNING, THOUGH GFS RUNS HAVE BEEN FARTHER SOUTHWEST, BUT  
PERHAPS IS INDICATING TWO LOWS ESPECIALLY IN THE NEW 12Z RUN.  
THERE IS ALSO SOME SPREAD WITH THAT FEATURE'S TRACK NORTHEASTWARD  
TUESDAY, WHICH IS DEPENDENT ON LOW PREDICTABILITY SHORTWAVES  
ALOFT, AS THE SOUTHERN STREAM LOW THAT WAS CLOSED SUNDAY MORNING  
LIFTS NORTHEASTWARD, OPENS UP, AND INTERACTS WITH NORTHERN STREAM  
FLOW. NO PARTICULAR OUTLIERS WERE SEEN IN THE 00Z/06Z CYCLE WITH  
THIS, BUT CONFIDENCE IS NOT HIGH EITHER.  
 
FARTHER WEST, ENERGY DIVING SOUTH INTO THE U.S. SUNDAY-MONDAY  
PRODUCES DIFFERENCES THAT BECOME MORE NOTABLE TUESDAY AND BEYOND.  
THE EC AND ESPECIALLY THE CMC HAVE SHOWN A SLOWER MOVEMENT OF THE  
ENERGY (WHICH IT SHOWS AS A CLOSED LOW) EASTWARD OUT OF THE FOUR  
CORNERS LATE TUESDAY INTO WEDNESDAY COMPARED TO THE GFS SUITE  
THROUGH 06Z. GIVEN TYPICAL MODEL BIASES, LEANED A BIT MORE TOWARD  
THE SLOWER SOLUTION, AND FORTUNATELY THE 12Z GFS INDICATES A  
SLOWER SOLUTION MUCH LIKE THE 00Z ECMWF  
WITH THE SHORTWAVE IN THE SOUTHERN HALF OF THE PLAINS EARLY  
WEDNESDAY. HOWEVER, THE NEW 12Z ECMWF TRENDED A BIT FASTER, BUT  
HOPEFULLY THE RUN TO RUN SWINGS ARE LESSENING. ADDITIONAL ENERGY  
IS LIKELY TO COME THROUGH THE NORTHWEST BY WEDNESDAY-THURSDAY, BUT  
OVERALL CONFIDENCE IN THE DETAILS OF NORTHERN STREAM FLOW THERE  
AND TIMING AND PLACEMENT OF CLIPPER SYSTEMS IN THE EAST IS MEDIUM  
TO LOW.  
 
THE WPC FORECAST BEGAN WITH A BLEND OF 00Z/06Z DETERMINISTIC  
GUIDANCE FAVORING THE ECMWF AND GFS GIVEN GOOD AGREEMENT EARLY IN  
THE PERIOD. PHASED IN THE ENSEMBLE MEANS FOR THE MIDDLE TO LATER  
PART OF THE PERIOD WITH THE INCREASING MODEL DIFFERENCES, FAVORING  
THE ECMWF IN TERMS OF THE DETERMINISTIC MODELS. THIS LED TO GOOD  
CONTINUITY WITH THE PREVIOUS FORECAST.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
RAIN AND THUNDERSTORMS WILL BE WIDESPREAD ALONG AND AHEAD OF THE  
COLD FRONT MOVING THROUGH THE CENTRAL/EASTERN U.S. EARLY NEXT  
WEEK. SEVERE WEATHER IS POSSIBLE FROM SOUTHEASTERN PORTIONS OF THE  
PLAINS INTO THE LOWER/MIDDLE MISSISSIPPI VALLEY ON SUNDAY INTO  
SUNDAY NIGHT PER THE LATEST STORM PREDICTION CENTER EXTENDED  
OUTLOOK. MEANWHILE THE AXIS OF THE HEAVIEST RAIN IS FORECAST FROM  
SOUTHEASTERN OKLAHOMA INTO NORTHERN ARKANSAS/MISSOURI AND THE OHIO  
VALLEY, SPREADING INTO THE CENTRAL APPALACHIANS/NORTHERN  
MID-ATLANTIC BY MONDAY. FLOODING AND FLASH FLOODING ARE POSSIBLE  
PARTICULARLY IN AREAS THAT SEE REPEAT/TRAINING CONVECTION AND IN  
AREAS WHERE SOILS ARE ALREADY WET, AND . A SWATH OF WINTRY  
PRECIPITATION COULD DEVELOP ON THE NORTH SIDE, WITH LIGHT TO  
MODERATE AMOUNTS POSSIBLE FROM THE CENTRAL PLAINS/MID-MISSISSIPPI  
VALLEY INTO THE GREAT LAKES AND INTERIOR NORTHEAST LATE SUNDAY  
INTO TUESDAY. THEN BY THE MIDDLE OF NEXT WEEK, GULF MOISTURE COULD  
RETURN TO THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST, BUT  
UNCERTAINTY REMAINS WITH THE AMOUNTS OF RAINFALL ONSHORE,  
DEPENDING ON WHERE A FRONT AND LOW STALL.  
 
IN THE WEST, SNOW IS LIKELY IN HIGHER ELEVATIONS OF THE CENTRAL  
ROCKIES IN PARTICULAR ON SUNDAY. THEN AFTER A QUICK BREAK IN  
PRECIPITATION, SNOW CHANCES (WITH SOME RAIN POSSIBLE IN LOWER  
ELEVATIONS) WILL INCREASE AGAIN BY TUESDAY AND BEYOND FOR THE  
PACIFIC NORTHWEST AND ESPECIALLY ACROSS THE NORTHERN ROCKIES,  
EVENTUALLY INTO THE CENTRAL ROCKIES AS WELL. THERE IS MORE  
UNCERTAINTY FOR THE POTENTIAL FOR SNOW IN THE NORTHERN PLAINS WITH  
THIS SYSTEM AT THIS POINT.  
 
TEMPERATURES WILL BE QUITE MILD FOR THE SOUTH-CENTRAL TO EASTERN  
PART OF THE U.S. EARLY IN THE WEEK AHEAD OF THE COLD FRONT, WITH  
TEMPERATURES 10 TO 30 DEGREES ABOVE AVERAGE AND DOZENS OF DAILY  
RECORD HIGH MINIMUM AND MAXIMUM TEMPERATURES COULD BE SET.  
TEMPERATURES SHOULD MODERATE TO NEAR NORMAL AFTER THE FRONTAL  
PASSAGE. THE WEST AND PARTS OF THE CENTRAL U.S. WILL GENERALLY BE  
COOLER THAN AVERAGE UNDERNEATH PERSISTENT TROUGHING. PARTICULARLY  
COOL SPOTS WILL BE THE CENTRAL HIGH PLAINS SUNDAY AND MONDAY, WITH  
HIGHS 15 TO 25 DEGREES BELOW NORMAL, AND ACROSS THE NORTHERN HIGH  
PLAINS WEDNESDAY AND SPREADING SOUTH AND EAST THURSDAY.  
 
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, 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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