607
FXUS02 KWBC 141856
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
156 PM EST FRI FEB 14 2025
VALID 12Z MON FEB 17 2025 - 12Z FRI FEB 21 2025
...INTENSE ARCTIC BLAST FOR THE NORTH-CENTRAL U.S. WITH INCREASING
POTENTIAL FOR EAST COAST WINTER STORM LATE NEXT WEEK...
..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. AT THE SURFACE, A MASSIVE ARCTIC HIGH WILL
SETTLE SOUTHWARD ACROSS THE PLAINS AND REACH THE GULF COAST BY
WEDNESDAY. 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 STORM FOR THE END OF THE WEEK. WIDESPREAD ARCTIC
COLD ENVELOPS MUCH OF THE CENTRAL TO EASTERN U.S. TO CLOSE OUT THE
WORK WEEK.
THE 12Z MODEL GUIDANCE SUITE FEATURES ABOVE AVERAGE MODEL AGREEMENT
THOROUGH THE ENTIRE FORECAST PERIOD, WITH MAINLY MODEST AMPLITUDE
AND TIMING DIFFERENCES WITH INDIVIDUAL SHORT WAVES. A MULTI-
DETERMINISTIC MODEL BLEND SUFFICED AS A STARTING POINT THROUGH
WEDNESDAY, WITH ENSEMBLE MEANS INCREASED TO ONLY 30% BY FRIDAY.
..WEATHER/HAZARDS HIGHLIGHTS
A CLOSED UPPER LOW/TROUGH AND DEEP SURFACE LOW WILL WORK INTO THE
CANADIAN MARITIMES BY EARLY NEXT WEEK. TRAILING UPPER ENERGIES AND
VERY COLD LOWER ATMOSPHERIC FLOW WILL COMBINE WITH LINGERING WRAP-
BACK MOISTURE TO FUEL GREAT LAKE EFFECT TO NORTHERN NEW ENGLAND
SNOWS. THE TIGHT PRESSURE GRADIENT MAY RESULT IN A PERIOD OF
STRONG, GUSTY WINDS. BEHIND THIS SYSTEM, ELONGATED UPPER TROUGHING
WILL LINGER ACROSS THE NORTHERN TIER AND 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 RECORD COLD TEMPERATURES WITH FOCUS OVER
ESPECIALLY THE CENTRAL U.S. IN THIS PATTERN. TEMPERATURES ARE
EXPECTED TO BE ON THE ORDER OF 25 TO 45 DEGREES BELOW AVERAGE
THROUGH MIDWEEK FROM MONTANA TO KANSAS!
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 THROUGH THE PERIOD. A MAIN FOCUS FOR PRECIPITATION
WILL SPREAD TO THE CENTRAL/SOUTHERN PLAINS EARLY NEXT WEEK AS A LOW
PRESSURE SYSTEM MOVES SOUTH ACROSS THE REGION TOWARDS THE GULF
COAST. THE EXISTING WPC DAY 5 MARGINAL RISK AREA ON TUESDAY HAS
BEEN EXPANDED SOME TO THE EAST TO INCLUDE THE WESTERN FLORIDA
PANHANDLE, GIVEN A LARGER HEAVY QPF SIGNAL IN THE 12Z MODEL
GUIDANCE, WITH THE POTENTIAL FOR 1-3 INCHES OF RAINFALL DURING THIS
TIME PERIOD.
THE PROSPECTS FOR AN IMPACTFUL WINTER STORM HAVE INCREASED OVER THE
PAST 12-24 HOURS, WITH THE NEW WPC WINTER WEATHER OUTLOOK NOW UP TO
50-60% FOR THURSDAY ACROSS PORTIONS OF THE MID-ATLANTIC, AND THIS
ALSO HOLDS TRUE FOR FRIDAY INTO SOUTHERN NEW ENGLAND. BOTH THE NBM
AND THE MAJORITY OF THE DETERMINISTIC GUIDANCE HAS TRENDED HIGHER
WITH QPF ACROSS THIS REGION AS THE SURFACE LOW TRACKS FARTHER NORTH
COMPARED TO EARLIER FORECASTS. WITH ABUNDANT SUB-FREEZING
TEMPERATURES IN PLACE AHEAD OF THIS STORM SYSTEM, WIDESPREAD SNOW
IS BECOMING MORE LIKELY, WITH A CORRIDOR OF MIXED PRECIPITATION
FARTHER TO THE SOUTH.
HAMRICK/SCHICHTEL
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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