262
FXUS02 KWBC 151857
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 PM EST SAT FEB 15 2025
VALID 12Z TUE FEB 18 2025 - 12Z SAT FEB 22 2025
...INTENSE ARCTIC BLAST FOR THE CENTRAL TO EASTERN U.S. NEXT WEEK
WITH AN IMPACTFUL SOUTH-CENTRAL U.S. TO EAST COAST WINTER STORM...
19Z UPDATE: THE 12Z MODEL GUIDANCE SUITE IS GENERALLY IN ABOVE
AVERAGE AGREEMENT THROUGH ABOUT THURSDAY ON THE OVERALL SYNOPTIC
SCALE PATTERN, WITH A MULTI-DETERMINISTIC MODEL BLEND WORKING WELL
AS A STARTING POINT IN THE FORECAST PROCESS. HOWEVER, THE 12Z UKMET
STANDS OUT SLOWER AND FARTHER WEST WITH THE EAST COAST LOW COMPARED
TO THE MODEL CONSENSUS, SO THE PREFERENCE HERE IS FOR A
CMC/GFS/ECMWF/ECENS BLEND. FOR QPF, THE NBM IS LIKELY A LITTLE ON
THE LOW SIDE FOR THE STORM SYSTEM TRACKING FROM THE DEEP SOUTH TO
THE EAST COAST THROUGH THURSDAY, SO THIS WAS BLENDED WITH ABOUT
HALF NBM AND HALF OF THE CMC/GFS/ECMWF. THIS YIELDED SOME HEAVIER
QPF ACROSS INLAND PORTIONS OF THE MID-ATLANTIC AND THE NORTHEAST
U.S. COMPARED TO THE PRIOR FORECAST, AND THEREFORE PROBABILITIES IN
THE WINTER WEATHER OUTLOOK HAVE INCREASED SOME FOR THE DAY 5 AND 6
PERIODS. THERE IS ALSO A GOOD CHANCE OF IMPACTFUL FREEZING RAIN
ACROSS PORTIONS OF CENTRAL NORTH CAROLINA THAT WILL CONTINUE TO BE
MONITORED. THE PREVIOUS FORECAST DISCUSSION IS APPENDED BELOW FOR
REFERENCE. /HAMRICK
------------------
..GENERAL OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
AN ELONGATED UPPER TROUGH STRETCHED FROM SOUTH-CENTRAL CANADA TO
QUEBEC WILL PIVOT SOUTH ACROSS THE NORTH-CENTRAL U.S. FOR THE
BEGINNING OF THE WEEK AS SHORTWAVE TROUGHS UPSTREAM DIG INTO THE
WEST. AT THE SURFACE, A MASSIVE ARCTIC HIGH WILL SETTLE SOUTHWARD
ACROSS THE PLAINS AND REACH THE GULF COAST BY WEDNESDAY TO ENVELOP
MUCH OF THE CENTRAL TO EASTERN U.S. NEXT WEEK. THIS COLD FRONT WILL
THEN FORM A LOW ALONG IT, WHICH SHOULD THEN TRACK TO NEAR THE MID-
ATLANTIC COAST BY THURSDAY AND SUPPORT A WINTER COASTAL STORM FOR
THE END OF THE WEEK OFF THE NORTHEAST. THE 00/06 UTC GUIDANCE SUITE
STILL FEATURES ABOVE AVERAGE MODEL AGREEMENT THOROUGH THE ENTIRE
FORECAST PERIOD, WITH MODEST AMPLITUDE AND TIMING DIFFERENCES WITH
INDIVIDUAL SHORT WAVES. A BROAD MODEL AND ENSEMBLE MEAN COMPOSITE
SEEMED TO PROVIDE A QUITE REASONABLE FORECAST BASIS GENERALLY IN
LINE WITH THE NATIONAL BLEND OF MODELS AND WPC PRODUCT CONTINUITY.
LATEST 12 UTC MODEL GUIDANCE STILL SEEMS IN LINE.
..WEATHER/HAZARDS HIGHLIGHTS
ELONGATED UPPER TROUGHING WILL LINGER ACROSS THE NORTHERN TIER OF
THE NATION AS AN IMPRESSIVE ARCTIC AIRMASS TAKES HOLD OVER THE
CENTRAL AND EASTERN U.S. NEXT WEEK. ENTRENCHED COLD AIR WILL
MAINTAIN LAKE EFFECT SNOWS AND ALSO OFFER A WIDESPREAD THREAT OF
NUMEROUS RECORD COLD TEMPERATURES WITH FOCUS OVER ESPECIALLY THE
NORTH-CENTRAL U.S. IN THIS PATTERN. TEMPERATURES MAY BE 25 TO 45
DEGREES BELOW AVERAGE FOR TUESDAY AND WEDNESDAY FOR PORTIONS OF THE
CENTRAL AND NORTHERN PLAINS.
UPSTREAM, SEVERAL ORGANIZED SHORTWAVES/FRONTAL SYSTEMS WILL DIG
SOUTHEASTWARD THROUGH THE WEST. THESE SYSTEMS WILL BRING ROUNDS OF
LOW ELEVATION RAIN AND MOUNTAIN SNOW TO THE PACIFIC NORTHWEST,
NORTHERN CALIFORNIA, AND THE NORTHERN/CENTRAL INTERMOUNTAIN
WEST/ROCKIES. FORTIFIED UPSLOPE FETCH WITH THE AFOREMENTIONED
ARCTIC FRONTAL SURGE TROUGH THE CENTRAL U.S. WILL FAVOR SNOW AND
WIND INTO THE HIGH PLAINS/ROCKIES, EARNESTLY SPREADING ACROSS THE
CENTRAL PLAINS AND BIG SOUTH TUESDAY. AS FOR HEAVY RAINFALL
POTENTIAL, THE WPC EXCESSIVE RAINFALL OUTLOOK (ERO) FOR DAY
4/TUESDAY AND DAY 5/WEDNESDAY MAINTAIN THE MARGINAL RISK AREAS WITH
LITTLE IN THE WAY OF ANY CHANGES, EXTENDING FROM THE CENTRAL GULF
COAST THROUGH THE CAROLINAS TO SHOW THE POTENTIAL FOR 1-3 INCHES OF
RAINFALL DURING THIS TIME PERIOD AS AN ORGANIZING FRONTAL WAVE
TRACK ENHANCES MOISTURE INFLOW INTO THE REGION.
DOWNSTREAM, AN IMPACTFUL WINTER COASTAL STORM OFFERS A THREAT FOR
HEAVY SNOW FROM THE MID-ATLANTIC THROUGH NEW ENGLAND WEDNESDAY AND
THURSDAY AS DEPICTED IN THE WPC WINTER WEATHER OUTLOOK (WWO). WITH
ABUNDANT SUB-FREEZING TEMPERATURES IN PLACE AHEAD OF THIS STORM
SYSTEM, WIDESPREAD SNOW IS EXPECTED, WITH A CORRIDOR OF MIXED
PRECIPITATION FARTHER TO THE SOUTH. GUIDANCE HOWEVER CONTINUES TO
ADJUST THE INLAND EXTENT OF THE BULK OF PRECIPITATION.
SCHICHTEL/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 FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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