848
FXUS21 KWNC 251811
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 25 2026
SYNOPSIS: EARLY IN WEEK-2, A STRONG SURFACE HIGH PRESSURE SYSTEM AND
ACCOMPANYING ANOMALOUSLY COLD AIR IS EXPECTED TO SETTLE INTO THE CENTRAL AND
EASTERN CONTIGUOUS UNITED STATES (CONUS). MUCH BELOW NORMAL TEMPERATURES WITH
FREEZING AND NEAR FREEZING CONDITIONS ARE POSSIBLE IN SOME AREAS, POTENTIALLY
DAMAGING EARLY SPRING BLOOMS. LATER IN WEEK-2, REDEVELOPING MID-LEVEL LOW
PRESSURE OVER THE NORTHEASTERN CONUS MAY BRING THE RETURN OF UNSEASONABLE COLD
AIR TO PORTIONS OF THE MIDWEST, ALONG WITH HEAVY PRECIPITATION ACROSS PORTIONS
OF THE PLAINS AND MISSISSIPPI VALLEY, BUT THERE IS TOO MUCH UNCERTAINTY TO POST
ANY ADDITIONAL HAZARDS AT THIS TIME.
HAZARDS
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE OHIO
VALLEY, GREAT LAKES, APPALACHIANS, MID-ATLANTIC, AND NORTHEAST, SUN, MAY 3.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FROM PORTIONS OF THE EASTERN
GREAT PLAINS, MISSISSIPPI, TENNESSEE AND OHIO VALLEYS, APPALACHIANS, NORTHERN
AREAS OF THE SOUTHEAST, MID-ATLANTIC AND NORTHEAST, SUN-MON, MAY 3-4.
SLIGHT RISK OF HIGH WINDS FOR MUCH OF THE EASTERN U.S., SUN-MON, MAY 3-4.
DETAILED SUMMARY
FOR TUESDAY APRIL 28 - SATURDAY MAY 02:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SUNDAY MAY 03 - SATURDAY MAY 09: DYNAMICAL MODEL ENSEMBLE MEAN 500-HPA
HEIGHT FORECASTS FROM THE GEFS AND ECMWF REMAIN CONSISTENT IN FAVORING
AMPLIFIED TROUGHING OVER THE NORTHEASTERN CONUS NEXT WEEKEND, WHERE THE PAIRING
WITH A STRONG ANOMALOUS RIDGE CENTER TO THE SOUTH OF GREENLAND IS CONSISTENT
WITH A NEGATIVE NORTH AMERICAN OSCILLATION (-NAO) PATTERN SUPPORTIVE FOR THE
ADVECTION OF ANOMALOUS COLD AIR INTO MANY PARTS OF THE CENTRAL AND EASTERN
CONUS. A -NAO CIRCULATION IS PREDOMINANTLY FAVORED OVER EASTERN NORTH AMERICA
AS THE PERIOD PROGRESSES, AND THE LATEST ENSEMBLE MEANS ARE BEGINNING TO SHOW
SIGNS OF A REDEVELOPING MEAN TROUGH TOWARDS THE MIDDLE OF WEEK-2. BASED ON
CONTINUED MODEL DIFFERENCES IN THE HEIGHT PATTERN UPSTREAM, IT IS UNCLEAR
WHETHER THE DYNAMICAL FORCING CONTRIBUTING TO THIS REDEVELOPMENT IS SOUTHERN OR
NORTHERN STREAM BASED, AS THE ECMWF (GEFS) CONTINUES TO FAVOR MORE RIDGING
(TROUGHING) ACROSS THE WESTERN CONUS. BUT REGARDLESS, ANY REAMPLIFICATION OF
THE TROUGHING IS EXPECTED TO KEEP BELOW NORMAL TEMPERATURES ENTRENCHED OVER THE
EASTERN U.S. THROUGH EARLY MAY, WHERE PERIODS OF FREEZING AND NEAR FREEZING
TEMPERATURES LOOK TO POSSIBLY THREATEN VULNERABLE SPRINGTIME VEGETATION,
PARTICULARLY IN AREAS THAT HAVE EXPERIENCED EARLY GROWTH DUE TO ANTECEDENT
WARMTH DURING APRIL.
IN THE WAKE OF A LARGE FRONTAL BOUNDARY EXTENDING FROM NORTHERN MEXICO TO THE
WESTERN ATLANTIC LATE IN WEEK-1, GUIDANCE CONTINUES TO FEATURE A MEAN HIGH
PRESSURE SYSTEM SETTLING OVER MUCH OF THE MIDWEST. ENSEMBLES MAINTAIN AN
EASTWARD PROGRESSION OF THE MEAN SURFACE HIGH CENTER INTO THE OHIO VALLEY BY
THE START OF WEEK-2, WITH LITTLE CHANGE TO ITS STRENGTH SINCE YESTERDAY.
THOUGH, BOTH RAW AND CALIBRATED TEMPERATURES TOOLS HAVE TRENDED SLIGHTLY
COLDER, WHICH IS LIKELY TIED TO A DEEPER SURFACE LOW FAVORED OFFSHORE IN THE
ATLANTIC INJECTING A STRONGER NORTHERLY WIND COMPONENT INTO THE NORTHEASTERN
CONUS. BOTH THE UNCALIBRATED GEFS AND ECMWF NOW FAVOR >60% CHANCES FOR NEGATIVE
DOUBLE DIGIT TEMPERATURE DEPARTURES FROM THE OHIO VALLEY TO THE NORTHEAST, WITH
PROBABILISTIC EXTREME TOOLS DEPICTING 40-50% CHANCES FOR MINIMUM TEMPERATURES
FALLING BELOW THE 15TH CLIMATOLOGICAL PERCENTILE FOCUSED OVER THE SOUTHEASTERN
QUARTER OF THE CONUS. WHILE FREEZING TEMPERATURES ARE MOSTLY LIKELY TO BE
CONFINED TO THE NORTH, THERE CONTINUES TO BE INCREASED CHANCES IN TOOLS FOR
MINIMUM TEMPERATURES FALLING BELOW 38 F INTO THE NORTHERN PORTIONS OF THE LOWER
MISSISSIPPI AND TENNESSEE VALLEYS, AND LOWER MID-ATLANTIC TO POTENTIALLY IMPACT
SPRING VEGETATION. SPRING LEAF INDEX ANOMALIES FROM THE NATIONAL PHENOLOGY
NETWORK SHOW A VERY EARLY (10-20 DAYS) EMERGENCE OF GROWTH FOCUSED OVER PARTS
OF THE CENTRAL PLAINS, MIDDLE AND UPPER MISSISSIPPI AND OHIO VALLEYS, AND GREAT
LAKES. AS A RESULT, A MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURE REMAINS
POSTED FOR MAY 3, WITH ITS SPATIAL COVERAGE SHIFTED EASTWARD TO APPROXIMATELY
THE I-95 CORRIDOR WHERE THERE ARE INCREASED SIGNALS FOR LOW TEMPERATURES
DIPPING BELOW 38 DEG F SINCE YESTERDAY. WHILE THE GEFS SUPPORTS AN EXTENSION OF
THIS MODERATE COLD RISK AN ADDITIONAL DAY, THE ECMWF IS QUICK TO MODERATE
TEMPERATURES WITH THE SURFACE HIGH WEAKENING. THEREFORE, A SLIGHT RISK OF MUCH
BELOW NORMAL TEMPERATURES REMAINS POSTED WHERE PETS SHOW AT LEAST 20% CHANCES
OF MINIMUM TEMPERATURES FALLING BELOW THE 15TH PERCENTILE AND BELOW 40 DEG F,
AND REMAINS VALID THROUGH MAY 4. THE SLIGHT RISK COVERAGE IS ALSO ADJUSTED TO
REMOVE PORTIONS OF THE UPPER MIDWEST WHERE A MODERATION OF TEMPERATURES ARE
EXPECTED EARLY IN WEEK-2, AT LEAST TEMPORARILY. IN ADDITION, A SLIGHT RISK OF
HIGH WIND IS ISSUED (MAY 3-4) FOR MUCH OF THE EASTERN U.S. ASSOCIATED WITH THE
STRENGTHENING MEAN PRESSURE GRADIENT BETWEEN THE AFOREMENTIONED SURFACE HIGH
AND THE DEEPENING LOW OFFSHORE. THE SLIGHT RISK AREA FOR HIGH WINDS IS
SUPPORTED BY STRONGER TROUGHING FAVORED ALOFT, AS WELL AS INCREASED WIND
SIGNALS IN THE PETS AND THE POTENTIAL FOR STRONG GUSTS IN THE UNCALIBRATED
TOOLS.
LATER IN WEEK-2, TEMPERATURE TOOLS INDICATE A RETURN OF NEGATIVE TEMPERATURE
DEPARTURES OVER THE MIDWEST ASSOCIATED WITH REDEVELOPING TROUGHING ALOFT. THE
POTENTIAL RENEWAL OF A MUCH BELOW NORMAL TEMPERATURE RISK IS BEST SUPPORTED IN
THE ECMWF, FAVORING MORE NORTHERN STREAM SHORTWAVE ENERGY TO PROMOTE A
SOUTHWARD EXPANSION OF COLD SIGNALS FROM CANADA, WITH INCREASED CHANCES OF
MINIMUM TEMPERATURES FALLING BELOW THE 15TH PERCENTILE OVER THE GREAT PLAINS
AND MISSISSIPPI VALLEY IN THE PET BY DAYS 10-12 (MAY 5-7). BY CONTRAST, THE
GEFS IS COMPARATIVELY MUCH MORE MUTED WITH THIS POTENTIAL, PRECLUDING THE
ISSUANCE OF ANY ADDITIONAL TEMPERATURE HAZARDS. HOWEVER, GIVEN THE FAVORED
PERSISTENCE OF A -NAO CIRCULATION, THE RENEWED COLD POTENTIAL WILL CONTINUE TO
BE CLOSELY MONITORED IN THE UPCOMING HAZARD OUTLOOKS.
TIED TO THE TROUGHING ALOFT BY THE MIDDLE OF THE PERIOD, BOTH THE GEFS AND
ECMWF SHOW THE RETURN OF INCREASED PRECIPITATION AMOUNTS MAINLY OVER THE
SOUTHERN TIER OF THE U.S. IN RESPONSE TO MORE RETURN FLOW FROM THE GULF
BECOMING ESTABLISHED. THERE IS SOME SUPPORT IN THE RAW TOOLS FOR 3-DAY AMOUNTS
EXCEEDING AN INCH TO SUGGEST SOME OF THIS PRECIPITATION MAY BE HEAVY. HOWEVER,
THE GEFS PET IS ABSENT OF ANY HEAVY PRECIPITATION THREAT, AND ENSEMBLES
GENERALLY DISAGREE IN REGARDS TO A DISCERNIBLE SURFACE FORCING FEATURE AT THIS
LEAD RESULTING IN NO CORRESPONDING PRECIPITATION HAZARDS AT THIS TIME.
OVER ALASKA, MODELS CONTINUE TO FAVOR MID-LEVEL TROUGHING OVER THE BERING
STRAIT WITH RIDGING OVER THE MAINLAND. AN ASSOCIATED MEAN SURFACE LOW CENTERED
OVER THE ALEUTIANS IS EXPECTED TO BRING POTENTIALLY STRONG WINDS AND STORMY
CONDITIONS ALONG THE SOUTHERN TIER OF THE STATE EARLY IN WEEK-2 BEFORE THE
PATTERN ALOFT DEAMPLIFIES. AT THIS TIME, CONDITIONS ARE EXPECTED TO REMAIN
BELOW HAZARD THRESHOLDS, AND NO CORRESPONDING WIND OR PRECIPITATION SHAPES ARE
POSTED. ADDITIONALLY, THE TYPICAL PEAK OF THE RIVER ICE BREAKUP SEASON IS
APPROACHING, AND ICE JAM FLOODING CAN OCCUR THIS TIME OF YEAR WITH LITTLE OR NO
NOTICE AS CONDITIONS ON FROZEN RIVERS CAN CHANGE QUICKLY. PLEASE CHECK WITH THE
ALASKA PACIFIC RIVER FORECAST CENTER FOR THE LATEST CONDITIONS AND ADVISORIES.
FORECASTER: NICK NOVELLA
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