369
FXUS02 KWNH 080703
PREEPD
PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
302 AM EDT SUN MAR 8 2026
VALID 12Z WED MAR 11 2026 - 12Z SUN MAR 15 2026
...THREAT OF MULTI-DAY HEAVY RAIN/FLOODING APPEARS TO LESSEN
MIDWEEK ACROSS THE EAST-CENTRAL U.S. INTO THE SOUTH BUT WIDESPREAD
SEVERE WEATHER REMAINS A CONCERN THROUGH THURSDAY...
..PATTERN OVERVIEW
A LINGERING AND WEAKENING CLOSED LOW MOVING INTO THE SOUTHERN
PLAINS ON WEDNESDAY WILL PHASE WITH STRONGER NORTHERN STREAM
TROUGHING DIGGING INTO THE GREAT LAKES AND OHIO VALLEY. THIS DRIVES
A STRONG COLD FRONT INTO THE EAST THROUGH THURSDAY WITH WIDESPREAD
RAINFALL AND POSSIBLE SEVERE WEATHER AHEAD OF IT, AND WINTRY
PRECIPITATION FROM THE GREAT LAKES TO THE INTERIOR NORTHEAST. AN
ATMOSPHERIC RIVER REMAINS ON TRACK TO BRING MODERATE TO HEAVY
PRECIPITATION INTO THE PACIFIC NORTHWEST WEDNESDAY AND THURSDAY
FOLLOWED BY A CLIPPER SYSTEM TO BRING HIGH WIND THREATS ACROSS THE
ROCKIES INTO THE HIGH PLAINS MUCH OF THE PERIOD. ANOTHER SHORTWAVE
LOOKS TO DIG INTO THE NORTH-CENTRAL U.S. BY THE END OF THE WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS CONTINUE TO SHOW GOOD AGREEMENT ON THE LARGE SCALE PATTERN
THROUGH THE ENTIRE PERIOD, BUT WITH SOME DIFFERENCES IN THE
INDIVIDUAL DETAILS. SOME DIFFERENCES IN THE TIMING OF THE SOUTHERN
STREAM SHORTWAVE PHASING WITH NORTHERN STREAM ENERGY REMAINS IN
QUESTION, WHICH WOULD IMPACT THE SPEED OF THE FRONTAL BOUNDARY
THROUGH THE EAST. AFTER THIS, ANOTHER SHORTWAVE WILL MOVE ACROSS
THE GREAT LAKES WITH A FAIRLY DEEP SURFACE LOW. THERE ARE SOME
DIFFERENCES IN THE EXACT PLACEMENT OF THIS SURFACE LOW, BUT
GENERALLY MODELS HAVE TRENDED DEEPER WITH THIS SYSTEM. A THIRD
SHORTWAVE INTO THE NORTHWEST MAY DEEPEN OVER THE NORTH-CENTRAL U.S.
NEXT WEEKEND WITH THE CMC NOTABLY FLATTER WITH THE FLOW THAN THE
GFS AND ECMWF.
GOOD AGREEMENT EARLY IN THE PERIOD LED TO A DETERMINISTIC MODEL
BLEND DAYS 3-5 FOR THE SURFACE PROGS AND 500MB CHARTS. TRANSITIONED
TOWARDS 60 PERCENT ENSEMBLE MEANS BY DAY 7 TO MITIGATE SOME OF THE
SMALLER SCALE DIFFERENCES.
..WEATHER/HAZARDS HIGHLIGHTS
HEAVY RAINFALL OVER THE CENTRAL U.S. WILL BE ONGOING AT THE START
OF THE PERIOD ON WEDNESDAY ALONG AND AHEAD OF AN INITIALLY SLOW
MOVING FRONTAL BOUNDARY. WITH SOME TRAINING POTENTIAL STILL ON
WEDNESDAY, MAINTAINED A MARGINAL RISK ON THE DAY 4/WEDNESDAY
EXCESSIVE RAINFALL OUTLOOK FROM THE MID-SOUTH TO THE OHIO VALLEY.
SPC IS ALSO HIGHLIGHTING SEVERE WEATHER POTENTIAL IN A SIMILAR
REGION. RAINFALL WILL THEN EXPAND INTO THE EASTERN U.S. AHEAD OF
THE MAIN COLD FRONT ON THURSDAY, BUT THE OVERALL FLOOD THREAT LOOKS
LIMITED AS THE FRONTAL BOUNDARY SHOULD BE MUCH MORE PROGRESSIVE BY
THAT TIME. SOME SNOW OR WINTRY MIX IS POSSIBLE ON THE NORTHERN
EDGE OF THE PRECIPITATION SHIELD FROM THE GREAT LAKES INTO THE
INTERIOR NORTHEAST, AND POSSIBLY AS FAR SOUTH AS THE INTERIOR
NORTHERN MID- ATLANTIC.
A COUPLE OF SHORTWAVES SHOULD KEEP THE PACIFIC NORTHWEST WET
THROUGH MUCH OF THE PERIOD. THE HEAVIEST RAINFALL SHOULD BE
ASSOCIATED WITH AN ATMOSPHERIC RIVER ENTERING THE REGION WEDNESDAY.
HEAVY SNOWS ARE POSSIBLE IN THE HIGHER ELEVATIONS, WITH EVEN SOME
LIGHT RAIN/SNOW MIX POSSIBLE AT LOWER ELEVATIONS INTO WEDNESDAY AS
TEMPERATURES COULD BE COLD ENOUGH IN THE MORNINGS. GIVEN INCREASING
MODEL QPFS AND HIGH MOISTURE ANOMALIES, DID GO AHEAD INTRODUCING A
MARGINAL RISK ON THE WEDNESDAY ERO FOR WESTERN WASHINGTON AND FAR
NORTHWEST OREGON. PRECIPITATION SHOULD CONTINUE INTO THURSDAY BUT
LESSEN IN INTENSITY.
DEEP SYSTEMS AND TIGHT PRESSURE GRADIENTS WILL SUPPORT HIGH WINDS,
ESPECIALLY FOR THE NORTHWEST-ROCKIES-HIGH PLAINS DURING THE LATTER
HALF OF NEXT WEEK. GUSTY WINDS MAY ALSO ACCOMPANY THE COLD FRONT
AS IT SLIDES THROUGH THE MIDWEST AND INTO THE EAST MID TO LATE WEEK
AND WITH AN ADDITIONAL CYCLONE ACROSS THE GREAT LAKES NEXT
WEEKEND.
A SIGNIFICANT SPRINGTIME WARM-UP IS EXPECTED AHEAD OF THE FRONT
FROM THE OHIO VALLEY INTO THE NORTHEAST WITH DAYTIME HIGHS 20 TO 30
DEGREES ABOVE NORMAL WITH DAILY WIDESPREAD RECORDS IN THE
FORECASTS. VALUES SHOULD MODERATE BACK TOWARDS NORMAL BY THURSDAY
AND FRIDAY FOLLOWING THE FRONTAL PASSAGE. ABOVE NORMAL TEMPERATURES
ARE ALSO EXPECTED TO EXPAND WITH TIME ACROSS THE SOUTHWEST INTO
THE PLAINS AND THE SOUTH WITH BELOW NORMAL TEMPERATURES ACROSS THE
FAR NORTHERN TIER.
SANTORELLI
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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