940  
FXUS02 KWBC 011557  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1056 AM EST FRI FEB 01 2019  
 
VALID 12Z MON FEB 04 2019 - 12Z FRI FEB 08 2019  
 
...WARMED CENTRAL-EASTERN U.S. FLIPS BACK TO COLD AND OFFERS  
SEVERAL WINTER STORM THREATS...   
..COLD AND STORMY PATTERN FOR THE WEST
 
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE WPC MEDIUM RANGE PRODUCT SUITE HAS BEEN DERIVED FROM A  
COMPOSITE OF THE 06 UTC GFS/GEFS MEAN AND 00 UTC ECMWF/ECMWF  
ENSEMBLE MEAN DAYS 3-5 (MON-WED). THESE FORECASTS IN PARTICULAR  
NOW SEEM QUITE WELL CLUSTERED, BOLSTERING FORECAST CONFIDENCE.  
INCREASING FORECAST SPREAD DAYS 6/7 ARE MAINLY ALIGNED WITH  
UNCERTAIN ENERGY DIGGING INTO THE WESTERN U.S. VERSUS EJECTION  
INTO THE FLOW OVER THE CENTRAL AND EASTERN U.S. ACCORDINGLY, JUST  
USED THE 00 UTC ECMWF ENSEMBLE MEAN AND 06 UTC GEFS MEAN DAYS 6/7  
AMID GROWING UNCERTAINTY, FOR NOW APPLYING EXTRA WEIGHTING TO THE  
BLEND TOWARD THE ECMWF ENSEMBLES THAT MAINTAINS BETTER WPC  
CONTINUITY.  
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
A MUCH MILDER WEATHER PATTERN WILL BE PREVALENT ACROSS MUCH OF THE  
CENTRAL AND EASTERN U.S. THIS WEEKEND INTO EARLY NEXT WEEK AS FLOW  
FROM THE GULF OF MEXICO ADVECTS HIGHER HUMIDITY OVER THE REGION.  
RECORD MILD TEMPERATURES MAY PRECEDE AN APPROACHING FRONT FROM THE  
MIDWEST TO THE NORTHEAST WITH ANOMALIES OF ABOUT +10 TO +30  
(GENERALLY ABOVE FREEZING TO THE NORTH AND 50S/60S IN THE  
MID-ATLANTIC. WESTERN ATLANTIC LOW PRESSURE MAY DELAY HIGH  
PRESSURE EROSION OVER THE EASTERN STATES MONDAY AND OFFER SOME  
POTENTIAL FOR SHOWERS TO WORK ONSHORE INTO THE EASTERN CAROLINAS.  
A COUPLE OF WELL DEFINED LOW PRESSURE SYSTEMS UPSTREAM ARE  
MEANWHILE EXPECTED TO TRACK ACROSS THE PLAINS AND MIDWEST/GREAT  
LAKES BEFORE LIFTING INTO EASTERN CANADA NEXT WEEK. THESE HAVE THE  
POTENTIAL FOR SIGNIFICANT SNOW AND WINDS TO THE NORTH OF THE MAIN  
SURFACE LOWS ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST/GREAT  
LAKES/NORTHEAST IN THE BROADENING ARCTIC AIRMASS. LATER PERIOD  
FRONTAL PROGRESSION INTO THE EAST IS NOW MORE SLOWED BY A BUILDING  
MEAN RIDGE ALOFT AND WITH A RECENT MODEL TREND TO DIG ENERGY  
ROBUSTLY INTO THE WEST. THIS ALLOWS COOLED HIGH PRESSURE TO HOLD  
LONGER FROM THE NORTHEAST INTO THE MID-ATLANTIC. WARM SECTOR  
SHOWERS/THUNDERSTORMS ARE LIKELY TO FOCUS FROM THE MID-SOUTH TO  
THE OH VALLEY/APPALACHIANS AND THERE IS SOME RISK OF LOCALLY HEAVY  
AMOUNTS.  
 
A GUIDANCE TREND TOWARD DEVELOPMENT OF A MORE AMPLIFIED WESTERN  
U.S. MEAN MID-UPPER LEVEL TROUGH NEXT WEEK IS COMPLICATED BY  
CHANGING SHORTWAVE TROUGH SYSTEMS TO DIG/REINFORCE THE MAIN LONGER  
WAVE FEATURE. THAT SAID, FORECAST CONFIDENCE IS ABOVE AVERAGE IN  
THE OVERALL IDEA THAT MUCH OF THE WEST WILL BECOME INCREASINGLY  
COLD AND STORMY NEXT WEEK WITH PASSAGE OF MULTIPLE SYSTEMS/HEIGHT  
FALLS. THIS INCLUDES VALLEY RAIN AND HIGHER ELEVATION SNOW (WITH  
LOWERING SNOW LEVELS), WIND, AND COOLER TEMPERATURES FROM  
OREGON/SOUTHERN IDAHO SOUTHWARD AND SOUTHEASTWARD. TO ITS NORTH  
WILL BE A SLOWLY ADVANCING ARCTIC FRONT THAT WILL BRING WELL BELOW  
AVERAGE TEMPERATURES TO MUCH OF MONTANA WHERE HIGHS WILL STRUGGLE  
TO GET TO ZERO (ABOUT 20-45 DEGREES BELOW AVERAGE) THAT WILL BLEED  
INTO THE DAKOTAS AS WELL. THE SIERRAS WILL SEE ANOTHER ROUND OF  
SNOW WITH MORE THAN A FOOT LIKELY.  
 
SCHICHTEL  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION AND WINTER WEATHER OUTLOOK  
PROBABILITIES ARE FOUND 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  
 

 
 
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