485
FXUS02 KWBC 161853
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
153 PM EST SUN FEB 16 2025
VALID 12Z WED FEB 19 2025 - 12Z SUN FEB 23 2025
...INTENSE ARCTIC BLAST FOR THE CENTRAL TO EASTERN U.S. NEXT WEEK
WITH AN IMPACTFUL SOUTH-CENTRAL U.S. TO MID-ATLANTIC WINTER
STORM...
19Z UPDATE: THE MAIN FEATURE OF INTEREST CONTINUES TO BE THE
DEVELOPING LOW PRESSURE SYSTEM ACROSS THE SOUTHEAST U.S. AND THEN
REACHING THE MID-ATLANTIC WEDNESDAY INTO EARLY THURSDAY. UPON
REVIEW OF THE 12Z MODEL GUIDANCE SUITE, IT IS APPARENT THAT THE
SURFACE LOW IS TRENDING A LITTLE MORE SOUTH AS IT EXITS THE OUTER
BANKS OF NC AND MOVING A LITTLE FASTER, TAKING MORE OF A ENE TRACK
INSTEAD OF A NE TRACK UP THE COAST. THERE HAS ALSO BEEN A SLIGHT
TREND IN THIS DIRECTION AS WELL WITH THE ENSEMBLE LOW CLUSTERS
OVER THE PAST 24-48 HOURS OF THE ECENS/GEFS. THIS WILL HAVE
IMPLICATIONS ON THE NORTHERN EXTENT OF THE ACCUMULATING SNOWS WITH
THIS EVENT, PARTICULARLY ACROSS THE NORTHERN MID-ATLANTIC AND
SOUTHERN NEW ENGLAND. THE LATEST 12Z MODEL TRENDS SUGGEST LESS
SNOW FOR THOSE AREAS, AND THE AXIS OF GREATEST SNOW ACROSS SOUTHERN
VIRGINIA INTO THE DELMARVA, AND THE AXIS OF ANY MIXED
PRECIPITATION FARTHER TO THE SOUTH ACROSS NORTH CAROLINA AS WELL.
IT IS IMPORTANT TO NOTE THAT THESE TYPES OF MODEL TRENDS CAN BE
TEMPORARY, AND COULD POSSIBLY TREND BACK TO THE NORTH IN FUTURE
MODEL RUNS AND ALSO ONCE THE HIGHER RESOLUTION GUIDANCE BEGINS TO
CAPTURE THIS EVENT GOING INTO THE SHORT RANGE FORECAST PERIOD.
OTHERWISE THE FORECAST ELSEWHERE REMAINS IN GOOD CONTINUITY WITH
DECENT OVERALL MODEL AGREEMENT FOR MOST AREAS, WITH ENSEMBLE MEANS
INCREASED TO ABOUT 40% BY NEXT SUNDAY. THE PREVIOUS FORECAST
DISCUSSION IS APPENDED BELOW FOR REFERENCE. /HAMRICK
--------------------
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
PREFERRED BLEND AT THAT TIME OF BEST CLUSTERED GUIDANCE FROM THE
18 UTC GFS/GEFS MEAN ALONG WITH THE 12 UTC ECMWF AND
ECMWF/CANADIAN ENSEMBLE MEANS. APPLIED HEAVIER BLEND WEIGHTING TO
THE ENSEMBLE MEANS INTO LATER WEEK AND NEXT WEEKEND TO MITIGATE
QUICKLY GROWING FLOW EMBEDDED FEATURE TIMING VARIANCES. THIS
SOLUTION HAD STRONG MACHINE LEARNING MODEL SUPPORT AND MAINTAINED
GOOD WPC PRODUCT CONTINUITY. OUTLIER GUIDANCE FROM THE 12 UTC
CANADIAN/UKMET HAS SINCE TRENDED INTO THE FOLD WITH THE LATEST 00
UTC CYCLE, BOLSTERING FORECAST CONFIDENCE OVERALL.
..WEATHER/HAZARDS HIGHLIGHTS
AN IMPRESSIVE ARCTIC AIRMASS WILL TAKE 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 CENTRAL U.S..
TEMPERATURES MAY BE AS COLD AS 20 TO 40 DEGREES BELOW AVERAGE
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 LINGERING
SNOW AND WIND TO THE LEE OVER THE HIGH PLAINS/ROCKIES. AS FOR
HEAVY RAINFALL POTENTIAL, THE WPC DAY 4/WEDNESDAY EXCESSIVE
RAINFALL OUTLOOK MAINTAINS AN ELONGATED MARGINAL RISK AREA FROM THE
CENTRAL GULF COAST THROUGH THE EASTERN CAROLINAS AS AN ORGANIZING
FRONTAL WAVE TRACK ENHANCES MOISTURE INFLOW. THERE IS CURRENTLY NO
NEED FOR ANY MAJOR ADJUSTMENTS TO THE DAY 4 MARGINAL RISK, EXCEPT
TO EXTEND IT ABOUT 25-50 FARTHER SOUTH ACROSS THE NORTHERN FLORIDA
PENINSULA.
THERE WILL MEANWHILE BE A THREAT FOR HEAVY SNOW/ICE ON THE
NORTHERN PERIPHERY OF THE RAIN AREA OUT FROM THE BIG SOUTH AND
THROUGH THE OHIO/TENNESSEE VALLEYS. DOWNSTREAM, AN IMPACTFUL WINTER
COASTAL STORM WILL OFFER A MARITIME THREAT, WITH WRAPBACK WINTER
STORM POTENTIAL FROM THE MID-ATLANTIC THROUGH NEW ENGLAND WEDNESDAY
AND THURSDAY AS DEPICTED ON THE WPC WINTER WEATHER OUTLOOK. 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 STILL
CONTINUES TO ADJUST THE STORM TRACK COASTAL PROXIMITY AND 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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