146
FXUS02 KWBC 121900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST WED FEB 12 2025
VALID 12Z SAT FEB 15 2025 - 12Z WED FEB 19 2025
...STRONG STORM TO BRING HEAVY RAIN AND FLOODING THREAT TO THE
TENNESSEE/OHIO VALLEY ON SATURDAY AND HEAVY SNOW FROM THE MIDWEST
TO NORTHEAST THIS WEEKEND...
..OVERVIEW
A DEEP UPPER TROUGH WILL MOVE EAST ACROSS THE CENTRAL U.S. THIS
WEEKEND, THEN LIFT RAPIDLY NORTHEASTWARD EARLY NEXT WEEK. THIS WILL
DRIVE A STRONG STORM SYSTEM ACROSS THE CENTRAL AND EASTERN U.S.
THAT WILL LIKELY BRING A SIGNIFICANT THREAT OF HEAVY RAIN AND FLASH
FLOODING TO THE OHIO/TENNESSEE VALLEY REGION ON SATURDAY. WINTRY
PRECIPITATION AND SNOW IS EXPECTED ON THE NORTHERN SIDE OF THE
STORM SYSTEM, AND A SWATH OF HEAVY SNOW WILL BE POSSIBLE FROM THE
MIDWEST TO THE NORTHEAST THIS WEEKEND. MEANWHILE, THE NEXT PACIFIC
SYSTEM WILL APPROACH THE WEST COAST LATE SATURDAY INTO SUNDAY,
BRINGING LOW ELEVATION RAIN AND MOUNTAIN SNOW TO THE PACIFIC
NORTHWEST AND NORTHERN CALIFORNIA. THIS SYSTEM WILL PUSH INLAND
EARLY NEXT WEEK, BRINGING PRECIPITATION SOUTHEASTWARD TO THE
CENTRAL ROCKIES AND THE CENTRAL/SOUTHERN PLAINS BY TUESDAY. MID-
NEXT WEEK, THE SYSTEM IN THE PLAINS WILL SINK SOUTH TOWARDS THE
GULF COAST AND ANOTHER PACIFIC SYSTEM WILL MOVE INTO THE WEST
COAST. ARCTIC HIGH PRESSURE WILL EXPAND SOUTH AND EAST FROM THE
NORTH-CENTRAL U.S. THROUGH THE PERIOD, RESULTING IN WELL BELOW
NORMAL TEMPERATURES FOR MUCH OF THE EASTERN TWO-THIRDS OF THE
NATION.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE LARGE SCALE PATTERN
THROUGH THE PERIOD WITH AN EXPECTED AMOUNT OF MODEL
SPREAD/DIFFERENCES IN DETAILS OF SPECIFIC SYSTEMS. THE HIGHEST
IMPACT DIFFERENCES WILL BE CONCERNING THE STRENGTH OF THE STORM
SYSTEM IN THE CENTRAL/EASTERN U.S. THIS WEEKEND. THE OVERALL
PATTERN AND MODEL TRENDS FAVOR A DEEPER LOW PRESSURE SYSTEM, WHICH
IS IN LINE WITH THE 12Z GFS/GEFS AND 00Z ECMWF/ECENS, BUT THE
CMC/CMCE AND MACHINE LEARNING MODELS HAVE A WEAKER LOW. IN ORDER TO
DEPICT THE DEEPER FAVORED SOLUTION, THE WPC MODEL BLEND LEANED
HEAVILY INTO THE GFS/ECMWF WITH SMALLER AMOUNTS OF THE CMC AND
UKMET. OTHER THAN THE STRENGTH, THERE WAS GOOD AGREEMENT ON THE
OVERALL STRUCTURE AND EVOLUTION OF THIS SYSTEM AS IS TRACKS
NORTHEAST.
LATER IN THE PERIOD, THERE IS SOME MORE SIGNIFICANT MODEL SPREAD
AS AN UPPER LOW/TROUGH DROPS INTO THE NORTH-CENTRAL U.S. AND
ANOTHER LOW/TROUGH MOVES ONSHORE IN THE PACIFIC NORTHWEST.
DIFFERENCES IN LOCATION AND TIMING OF THE TWO TROUGHS WILL LIKELY
INFLUENCE THE SURFACE FEATURES AND SENSIBLE WEATHER. WPCS FORECAST
BLEND FAVORED A SOLUTION CLOSER TO THE GFS/ECMWF WHICH ARE IN LINE
WITH THE ENSEMBLE MEAN SOLUTIONS FROM THE GEFS/ECENS/CMCE. ENSEMBLE
MEANS FROM THE GEFS/ECENS WERE ADDED TO THE FORECAST BLEND IN
INCREASING AMOUNTS MONDAY THROUGH WEDNESDAY, WHICH HELPED SMOOTH
OUT MODEL DIFFERENCES AND CREATE A MIDDLE OF THE ROAD SOLUTION.
..WEATHER/HAZARDS HIGHLIGHTS
THE UPPER TROUGH SWINGING ACROSS THE CENTRAL U.S. THIS WEEKEND
WILL PROVIDE SUPPORT FOR A STRONG STORM SYSTEM MOVING ACROSS THE
EASTERN HALF OF THE NATION THIS WEEKEND. SOUTHERLY FLOW AHEAD OF
THE SYSTEM WILL BRING UP ANOMALOUS MOISTURE FROM THE GULF, WHICH
WILL COMBINE WITH PACIFIC MOISTURE AND ALLOW FOR WIDESPREAD
PRECIPITATION ON SATURDAY. A BROAD AREA OF HEAVY PRECIPITATION IS
EXPECTED FROM THE ARK-LA-TEX THROUGH THE MISSISSIPPI, TENNESSEE,
AND OHIO VALLEYS TO THE CENTRAL APPALACHIANS, AND A SLIGHT RISK OF
EXCESSIVE RAINFALL IS IN EFFECT FOR THESE REGIONS ON DAY
4/SATURDAY. THERE WILL BE ENOUGH INSTABILITY FOR THUNDERSTORM
DEVELOPMENT ACROSS THE LOWER MISSISSIPPI VALLEY, WHICH MAY HELP
ENHANCE RAINFALL RATES IN THIS REGION AS WELL. THE HEAVIEST
PRECIPITATION IS FORECAST TO FOCUS OVER KENTUCKY AND
WESTERN/CENTRAL TENNESSEE WHERE A MODERATE RISK OF EXCESSIVE
RAINFALL IS IN EFFECT. IF THE FORECAST COMES TO FRUITION, NUMEROUS
FLASH FLOODS, SOME SIGNIFICANT, AND MODERATE TO MAJOR RIVER
FLOODING WILL BE POSSIBLE. THE SYSTEM WILL QUICKLY LIFT NORTHEAST
ON SUNDAY, AND PRECIPITATION WILL PUSH OFF THE EAST COAST. THE
THREAT OF HEAVY RAINFALL WILL DECREASE AS THE SYSTEM BECOMES MORE
PROGRESSIVE, SO THERE ARE NO RISK AREAS DEPICTED IN THE DAY
5/SUNDAY EXCESSIVE RAINFALL OUTLOOK.
WINTRY WEATHER ON THE NORTHERN SIDE OF THIS STORM SYSTEM IS
EXPECTED TO IMPACT AREAS FROM THE MIDWEST TO THE NORTHEAST THIS
WEEKEND, AND A SWATH OF HEAVY SNOW IS FORECAST FROM CENTRAL
MICHIGAN THROUGH NEW YORK STATE TO THE NORTHEAST. THE LOCATION OF
HEAVY SNOW MAY SHIFT IF THE LOW PRESSURE TRACK CHANGES, WHICH WOULD
ALSO SHIFT THE TRANSITION ZONE OF WINTRY MIXED PRECIPITATION.
THERE MAY BE A PERIOD OF STRONG AND GUSTY WINDS OVER PARTS OF THE
EAST BEHIND THIS SYSTEM, ALONG WITH SOME LAKE EFFECT SNOW.
IN THE WEST, A PACIFIC SYSTEM WILL LIKELY SPREAD RAIN AND MOUNTAIN
SNOW INTO THE PACIFIC NORTHWEST SATURDAY INTO SUNDAY.
PRECIPITATION AMOUNTS/RATES ARE CURRENTLY FORECAST TO STAY BELOW
THE CRITERIA FOR AN EXCESSIVE RAINFALL OUTLOOK AREA, BUT LIGHT TO
MODERATE PRECIPITATION WILL STILL BE POSSIBLE. PRECIPITATION WILL
PUSH EAST/SOUTHEAST THROUGH THE ROCKIES EARLY NEXT WEEK WHILE
TAPERING OFF IN THE PACIFIC NORTHWEST. ANOTHER SYSTEM IS FORECAST
TO BRING PRECIPITATION BACK TO THE NORTHWEST TUESDAY INTO
WEDNESDAY WITH ANOTHER ROUND OF LIGHT TO MODERATE PRECIPITATION
EXPECTED.
AS THE UPPER TROUGH CROSSING THE WEST EARLY NEXT WEEK HEADS INTO
THE CENTRAL U.S. BY WEDNESDAY, EXPECT PRECIPITATION TO DEVELOP
FROM THE CENTRAL/SOUTHERN PLAINS EASTWARD. WINTRY WEATHER WILL BE
POSSIBLE IN THE NORTHERN PART OF THE PRECIPITATION SHIELD WITH RAIN
OVER THE SOUTH.
TEMPERATURE-WISE, BELOW NORMAL TEMPERATURES ARE EXPECTED THROUGH
THE PERIOD FOR MUCH OF THE CENTRAL U.S. WITH SURGES REACHING THE
SOUTH AND EAST LATE THIS WEEKEND AND MID-NEXT WEEK. THE NORTH-
CENTRAL U.S. WILL EXPERIENCE PERSISTENTLY COLD TEMPERATURES, WITH
HIGH TEMPERATURES AS MUCH AS 20-30 DEGREES BELOW AVERAGE POSSIBLE
EACH DAY. HIGH TEMPERATURES WILL DROP 15-25 DEGREES BELOW AVERAGE
FOR PORTIONS OF THE SOUTH AND EAST SUNDAY INTO MONDAY IN THE WAKE
OF THIS WEEKEND'S STRONG STORM SYSTEM. AHEAD OF THE STORM SYSTEM, A
BRIEF SURGE OF WARMER THAN AVERAGE AIR IS EXPECTED IN THE SOUTH
AND SOUTHEAST ON SATURDAY AND ALONG THE EAST COAST ON SUNDAY.
ANOTHER COLD SURGE WILL BE POSSIBLE IN THE SOUTH ON WEDNESDAY AS
THE PLAINS SYSTEM DROPS SOUTH TOWARDS THE GULF COAST. TEMPERATURES
IN THE WEST ARE EXPECTED TO REMAIN NEAR NORMAL WITH SMALL
FLUCTUATIONS BETWEEN SLIGHTLY BELOW AND SLIGHTLY ABOVE AVERAGE.
DOLAN/RAUSCH
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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