883
FXUS02 KWBC 260659
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 AM EST THU JAN 26 2023
VALID 12Z SUN JAN 29 2023 - 12Z THU FEB 2 2023
***COLDEST WEATHER SO FAR THIS MONTH EXPECTED ACROSS THE DAKOTAS
AND THE UPPER MIDWEST STARTING THIS WEEKEND WITH DANGEROUSLY COLD
WIND CHILLS EXPECTED***
..SYNOPTIC OVERVIEW
A PATTERN CHANGE WILL BE EVOLVING ACROSS MUCH OF THE NORTHERN TIER
OF THE COUNTRY GOING INTO THE WEEKEND AND BEYOND AS A STRONG COLD
FRONT USHERS IN AN ARCTIC AIRMASS, BRINGING THE COLDEST WEATHER
SINCE THE END OF DECEMBER FOR MANY AREAS. BROAD UPPER LEVEL
TROUGHING WITH CYCLONIC FLOW ALOFT WILL BE IN PLACE ACROSS THE
NORTH-CENTRAL U.S., AND THE UPPER RIDGE CENTERED OVER THE BAHAMAS
AND CUBA WILL SLOW THE PROGRESS OF THE FRONT AND CONTINUE TO KEEP
MUCH OF THE SOUTHEASTERN U.S. RATHER MILD FOR THIS TIME OF YEAR.
ACROSS THE WESTERN U.S., AN AMPLIFIED SHORTWAVE TROUGH WILL BE
TRACKING SOUTHWARD ALONG THE WEST COAST AND THEN SETTLE ACROSS THE
DESERT SOUTHWEST BY TUESDAY/WEDNESDAY, AND THEN THIS WILL
EVENTUALLY REACH THE SOUTHERN PLAINS BY NEXT THURSDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z GUIDANCE STARTS OFF IN GOOD SHAPE ACROSS THE CONTINENTAL
U.S. TO START THE FORECAST PERIOD SUNDAY, AND THE TIMING OF THE
SHORTWAVE TRACKING DOWN THE WEST COAST HAS COME INTO BETTER
AGREEMENT. THE MODELS REMAIN IN CLOSE AGREEMENT THROUGH ABOUT
MONDAY NIGHT, AFTER WHICH THE 18Z GFS BEGINS TO DIFFER WITH BOTH A
STRONGER SOUTHWESTERN U.S. TROUGH AND LESS OF A TROUGH OVER THE
MIDWEST AND GREAT LAKES REGION. GOING INTO NEXT THURSDAY, BOTH
THE 18Z AND 12Z GFS ARE CONSIDERABLY STRONGER WITH THE SOUTHEAST
U.S. RIDGE BUILDING NORTHWARD, WHEREAS THE GEFS MEAN AND THE
CMC/JMA/ECMWF ALL INDICATE MORE OF A ZONAL FLOW PATTERN ACROSS THE
SOUTHEAST AND THE MID-ATLANTIC WITH A BROAD TROUGH TO THE NORTH.
THEREFORE, THE GFS WAS NOT USED FOR DAYS 6 AND 7 IN THE
FRONTS/PRESSURES FORECAST. HOWEVER, A MULTI-DETERMINISTIC MODEL
BLEND WORKS WELL FOR DAYS 3 AND 4. MORE ENSEMBLE MEANS WERE USED
GOING INTO NEXT WEDNESDAY AND THURSDAY TO ACCOUNT FOR GREATER
MESOSCALE DIFFERENCES.
..WEATHER/HAZARD HIGHLIGHTS
AN ARCTIC SURGE BEHIND A STRONG COLD FRONT WILL BE MAKING WEATHER
HEADLINES ACROSS MUCH OF THE NORTH-CENTRAL U.S. AND NORTHERN
ROCKIES BEGINNING THIS WEEKEND AND PERSISTING INTO THE MIDDLE OF
NEXT WEEK. EXPECT MUCH BELOW NORMAL TEMPERATURES ACROSS THE
CENTRAL/NORTHERN PLAINS TO INTERIOR PORTIONS OF THE PACIFIC
NORTHWEST FOR THE WEEKEND INTO EARLY NEXT WEEK, WITH HIGHS RUNNING
UP TO 25 TO 40 DEGREES BELOW NORMAL FROM WESTERN NEBRASKA TO
CENTRAL MONTANA, AND THINGS CONTINUE TO TREND COLDER. THIS WOULD
BE THE COLDEST WEATHER SINCE CHRISTMAS FOR THIS REGION, WITH
LOCATIONS FROM EASTERN MONTANA TO NORTHERN MINNESOTA LIKELY
REMAINING BELOW ZERO FOR HIGHS SATURDAY THROUGH MONDAY, AND
PERHAPS INTO TUESDAY. WIND CHILLS COULD REACH 40 BELOW AT TIMES
FOR THESE AREAS. HIGHS IN THE 0 TO 10 DEGREE RANGE MAY EXTEND AS
FAR SOUTH AS NORTHEAST COLORADO AND NORTHERN KANSAS. THIS COLD
WEATHER WILL ALSO BE EXPECTED TO REACH INTO THE NORTHWEST/NORTHERN
INTERMOUNTAIN WEST.
WHILE SOME UNCERTAINTY REMAINS WITH THE EVOLUTION OF THE
UPPER-LEVEL PATTERN OVER THE WESTERN U.S., RAIN AND MOUNTAIN SNOW
PROSPECTS SHOULD GENERALLY INCREASE WITH TIME IN CALIFORNIA AND
THE SOUTHWEST AS THE PACIFIC COLD FRONT DROPS SOUTHWARD, WITH AT
LEAST SOME LIGHT HIGHER ELEVATION/INTERIOR SNOWFALL AND RAIN FOR
THE SOUTHERN CALIFORNIA COAST AND DESERT SOUTHWEST. SHORTWAVE
ENERGY INITIALLY EJECTING FROM THE SOUTHWESTERN U.S. WILL LIKELY
SUPPORT ONE OR MORE SURFACE WAVES OF LOW PRESSURE FROM THE
SOUTHERN PLAINS/GULF COAST INTO THE EASTERN U.S. DURING THE
WEEKEND INTO EARLY NEXT WEEK. GULF MOISTURE RETURN MAY SUPPORT A
CORRIDOR OF MODERATE TO HEAVY RAINFALL OVER PORTIONS OF THE
CENTRAL GULF COAST STATES AND VICINITY ON SUNDAY, WITH MORE MODEST
RAINS SPREADING NORTHWARD OVER THE EAST-CENTRAL U.S. INTO/AHEAD OF
A WAVY FRONT. THE DAY 4 (12Z SUNDAY-12Z MONDAY) EXCESSIVE
RAINFALL OUTLOOK MAINTAINS A SLIGHT RISK AREA FROM SOUTHERN
LOUISIANA TO THE FLORIDA PANHANDLE, WHERE MULTIPLE ROUNDS OF HEAVY
RAINFALL WILL BE POSSIBLE. SOMEWHAT LESSER PROBABILITIES OF HEAVY
RAINFALL EXIST OVER A LARGER PORTION OF THE SOUTHEAST. ANOTHER
WAVE NEAR THE CENTRAL GULF COAST WILL INCREASE RAIN CHANCES AGAIN
LATER IN THE PERIOD BY TUESDAY OR WEDNESDAY, WITH POTENTIAL
SENSITIVITY FOR AREAS WHERE THE TWO EPISODES OF RAINFALL COULD
OVERLAP. MEANWHILE WINTER WEATHER WILL BE POSSIBLE FARTHER NORTH,
WITH LOCATIONS FROM THE MIDWEST INTO NEW ENGLAND GENERALLY IN THE
MOST FAVORED AXIS FOR SOME GENERALLY LIGHT SNOWFALL. SUFFICIENT
PERSISTENCE OF COLD AIR BY LATE IN THE PERIOD COULD INCREASE THE
POSSIBILITY FOR A TRANSITION ZONE OF FREEZING RAIN/SLEET BETWEEN
THE RAIN AND SNOW AREAS BUT ANY SPECIFICS HAVE LOW CONFIDENCE AT
THIS TIME.
HAMRICK
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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