970  
FXUS02 KWBC 152020  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
319 PM EST TUE FEB 15 2022  
 
VALID 12Z FRI FEB 18 2022 - 12Z TUE FEB 22 2022  
 
1900 UTC UPDATE...  
 
THE LATEST 00Z/06Z MODEL CYCLE CONTINUES TO SHOW ABOVE AVERAGE  
AGREEMENT THROUGH THE ENTIRE PERIOD ON THE LARGE SCALE, WITH SOME  
LINGERING UNCERTAINTIES IN THE SMALLER SCALE DETAILS WHICH MOSTLY  
SHOW RUN TO RUN VARIABILITY ANYWAYS. MODELS HAVE REMAINED MOSTLY  
CONSISTENT WITH THEIR PREVIOUS RUNS AND SO, NO MAJOR CHANGES WERE  
NEEDED FOR TODAYS UPDATE TO THE WPC MEDIUM RANGE PRODUCT SUITE.  
THE ONLY NOTABLE CHANGE TO PREVIOUS CONTINUITY WAS A SLIGHT  
NORTHWARD SHIFT IN THE QPF AXIS ACROSS THE DEEP SOUTH EARLY NEXT  
WEEK, ALTHOUGH GIVEN THE LONGER TIME RANGE, REMAINS RATHER  
UNCERTAIN ANYWAYS. TODAYS BLEND CONSISTED OF THE UPDATED  
DETERMINISTIC MODEL RUNS FOR DAYS 3-5, WITH SOME INCORPORATION OF  
THE ENSEMBLE MEANS ON DAYS 6-7 TO HELP MITIGATE THE DETAIL  
DIFFERENCES. SEE PREVIOUS DISCUSSION BELOW FOR MODEL EVALUATION  
DETAILS AND ASSOCIATED SENSIBLE WEATHER THREATS.  
 
SANTORELLI  
 
PREVIOUS DISCUSSION ISSUED AT 0700 UTC...  
   
..OVERVIEW
 
 
LOW PRESSURE AND A STRONG COLD FRONT ALONG WITH ITS ASSOCIATED  
PRECIPITATION WILL BE EXITING THE EAST COAST ON FRIDAY, BEHIND  
WHICH NORTHERN STREAM ENERGY WILL PUSH A CLIPPER SYSTEM WITH SOME  
SNOW NEAR THE GREAT LAKES REGION. THEN EARLY NEXT WEEK, TROUGHING  
IS FORECAST TO DEVELOP IN THE WEST AND SLOWLY TRACK EASTWARD ALONG  
WITH A FRONTAL SYSTEM. PRECIPITATION CHANCES SHOULD INCREASE IN  
THE WEST WITH THIS PATTERN AND SPREAD INTO THE CENTRAL U.S. ONCE  
AGAIN BY NEXT MONDAY AND TUESDAY, WITH THE POSSIBILITY OF NORTHERN  
TIER SNOW AND SOUTHERN U.S. RAIN.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
RECENT MODEL GUIDANCE SHOWS GOOD AGREEMENT OVERALL WITH THE LARGE  
SCALE PATTERN EVEN THROUGH EARLY NEXT WEEK, WITH SOME TYPICAL  
DIFFERENCES IN THE SMALLER SCALE DETAILS. 12Z/18Z MODELS REMAIN  
FAIRLY WELL CLUSTERED WITH THE STRENGTHENING SURFACE LOW NEAR THE  
NORTHEAST/SOUTHEASTERN CANADA EARLY FRIDAY, ALONG WITH THE TRACK  
AND STRENGTH OF THE SURFACE LOW NEAR THE U.S./CANADIAN BORDER  
PUSHING INTO THE GREAT LAKES REGION FRIDAY INTO SATURDAY. A  
MULTI-MODEL DETERMINISTIC BLEND OF THE 18Z GFS AND 12Z ECMWF, CMC,  
AND UKMET WORKED WELL FOR THESE FEATURES AND KEPT WITH CONTINUITY  
WELL. A SOMEWHAT LESS CERTAIN FEATURE DURING THIS TIMEFRAME IS A  
COMPACT SHORTWAVE ROUNDING THE RIDGE IN THE EASTERN PACIFIC THAT  
COULD ENTER THE PACIFIC NORTHWEST OR NORTHERN CALIFORNIA AROUND  
FRIDAY NIGHT AND MOVE EASTWARD, BUT WITH SOME DIFFERENCES IN ITS  
TIMING AND PLACEMENT, WHICH MAY NOT BE RESOLVED FOR A WHILE GIVEN  
ITS SMALL SCALE. HOWEVER, TROUGHING DEVELOPING IN THE WEST EARLY  
NEXT WEEK IS COMING INTO SOMEWHAT BETTER AGREEMENT OVERALL WITH  
ITS DEVELOPMENT, DEPTH, AND MOVEMENT, BUT THERE ARE STILL NOTABLE  
DIFFERENCES AS ENERGY SPILLS IN FROM THE LOW PREDICTABILITY HIGH  
LATITUDES. GFS RUNS HAVE BEEN THE STRONGEST WITH THE TROUGH AND  
OCCASIONALLY CLOSE OFF AN UPPER LOW, BUT RECENT RUNS HAVE BACKED  
OFF A BIT ON THE STRENGTH, CLOSER TO THE PATTERN SHOWN BY THE MORE  
CONSISTENT ECMWF. SOME PHASING DIFFERENCES WITH POTENTIAL STREAM  
SEPARATION ALSO ARE CAUSING MINOR MODEL DIFFERENCES THAT COULD  
CONTINUE TO BE AN ISSUE WITH THE EVOLUTION OF THE TROUGHING. BUT  
OVERALL AGREEMENT IS BETTER THAN USUAL CONSIDERING THE FORECAST  
TIME RANGE OF 6-7 DAYS. THE WPC FORECAST PHASED IN SOME GEFS AND  
ECMWF ENSEMBLE MEAN GUIDANCE FOR THE LATTER PART OF THE PERIOD,  
BUT STILL KEPT A MAJORITY DETERMINISTIC MODEL BLEND THROUGHOUT  
GIVEN THE FAIRLY GOOD AGREEMENT CURRENTLY, WITH THE BLENDING  
PROCESS AND SOME USAGE OF THE MEANS TAKING CARE OF INDIVIDUAL  
MODEL ECCENTRICITIES.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
AS THE MEDIUM RANGE PERIOD BEGINS FRIDAY, RAIN AND SNOW WILL  
MOSTLY BE EXITING THE EAST COAST ALONG WITH A LOW PRESSURE/FRONTAL  
SYSTEM, THOUGH SHOWERS COULD LINGER IN FLORIDA. GUSTY WINDS COULD  
ALSO CONTINUE ON FRIDAY PARTICULARLY IN THE NORTHEAST NEAR THE  
STRONG SURFACE LOW. SNOW IS FORECAST FOR THE END OF THE WEEK  
ACROSS THE GREAT LAKES REGION WITH THE CLIPPER SYSTEM, WITH  
GENERALLY LIGHT TO PERHAPS LOCALLY MODERATE AMOUNTS. MAINLY DRY  
CONDITIONS ARE EXPECTED ELSEWHERE ON FRIDAY, BEFORE PRECIPITATION  
STARTS TO INCREASE IN THE WEST OVER THE WEEKEND WITH THE UPPER  
TROUGH COMING IN. COASTAL AND VALLEY RAIN AND MOUNTAIN SNOW ARE  
LIKELY OVER THE PACIFIC NORTHWEST SPREADING INTO CALIFORNIA, THE  
GREAT BASIN, AND THE ROCKIES. SNOW IS POSSIBLE FOR THE NORTHERN  
PLAINS AS WELL BY EARLY NEXT WEEK, BUT WITH LOW CONFIDENCE IN THE  
SNOW AXIS AND AMOUNTS AT THIS POINT. BY MONDAY AND TUESDAY MOIST  
INFLOW WILL RETURN FROM THE GULF OF MEXICO, INCREASING RAIN  
CHANCES ACROSS THE GULF COAST STATES.  
 
THE EAST COAST CAN EXPECT TEMPERATURES TO BE WARMER THAN AVERAGE  
FRIDAY MORNING, EVEN SETTING DAILY RECORDS FOR WARM LOWS, BEFORE  
QUICKLY FALLING BEHIND THE COLD FRONT, LEADING TO TEMPERATURES  
RIGHT AROUND AVERAGE FOR THE WEEKEND. MEANWHILE, COLDER THAN  
NORMAL TEMPERATURES BY 10-20F ARE EXPECTED IN THE SOUTH-CENTRAL  
U.S. TO MIDWEST ON FRIDAY AND MODERATING BY SATURDAY. TEMPERATURES  
WILL BE WARMER THAN AVERAGE STARTING IN THE NORTHWEST LATE THIS  
WEEK AND SPREADING INTO THE PLAINS THIS WEEKEND, AND HIGHS IN THE  
60S ARE FORECAST BY SUNDAY AS FAR NORTH AS NEBRASKA AND WESTERN  
IOWA. WARM TEMPERATURES SHIFT/SPREAD TO THE EAST COAST EARLY IN  
THE WORKWEEK WHILE THE WESTERN HALF OF THE NATION COOLS DOWN  
UNDERNEATH THE TROUGH. THE NORTHERN AND CENTRAL HIGH PLAINS COULD  
SEE TEMPERATURES 15-25F BELOW NORMAL MONDAY INTO TUESDAY.  
 
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  
 
HAZARDS:  
- HEAVY SNOW ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND THE  
NORTHERN GREAT BASIN, SAT-SUN, FEB  
19-FEB 20.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI  
VALLEY, THE GREAT LAKES, AND THE OHIO  
VALLEY.  
- HIGH WINDS ACROSS PORTIONS OF THE MID-ATLANTIC AND THE  
NORTHEAST, FRI, FEB 18.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE UPPER MISSISSIPPI  
VALLEY, THE NORTHERN PLAINS, AND THE NORTHERN ROCKIES, MON-TUE,  
FEB 21-FEB 22.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PANHANDLE,  
FRI, FEB 18.  
 
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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