978
FXUS21 KWNC 241800
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 24 2026
SYNOPSIS: A POTENTIALLY STRONG SURFACE HIGH PRESSURE SYSTEM AND ACCOMPANYING
ANOMALOUSLY COLD AIR IS EXPECTED TO SETTLE INTO THE CENTRAL AND EASTERN
CONTIGUOUS UNITED STATES (CONUS), RESULTING IN AN ELEVATED RISK OF MUCH BELOW
NORMAL, NEAR FREEZING TEMPERATURES TO DAMAGE TO EARLY SPRING BLOOMS EARLY IN
WEEK-2. LATER IN WEEK-2, SOUTHERLY RETURN FLOW COULD TRIGGER 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 CENTRAL
PLAINS, MIDDLE AND UPPER MISSISSIPPI AND OHIO VALLEYS, GREAT LAKES, AND
APPALACHIANS, SAT-SUN, MAY 2-3.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FROM PORTIONS OF THE GREAT PLAINS
EASTWARD THROUGH THE MID-ATLANTIC AND NORTHEAST, SAT-MON, MAY 2-4.
DETAILED SUMMARY
FOR MONDAY APRIL 27 - FRIDAY MAY 01:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY MAY 02 - FRIDAY MAY 08: TOWARDS THE END OF NEXT WEEK (LATE
WEEK-1), DYNAMICAL MODELS HAVE BEEN CONSISTENT FEATURING AN AMPLIFYING MEAN
500-HPA TROUGH OVER THE UPPER-MIDWEST, WHERE THE PHASING WITH A SOUTHERN STREAM
SHORTWAVE LOOKS TO RESULT IN EXPANDING COVERAGE OF NEGATIVE HEIGHT DEPARTURES
MAINLY EAST OF THE ROCKIES EARLY IN WEEK-2. COUPLED WITH A POTENTIALLY STRONG
MID-LEVEL RIDGE CENTER NEAR SOUTHERN GREENLAND, THE PATTERN CONTINUES TO ALIGN
WITH A NEGATIVE NORTH AMERICAN OSCILLATION (-NAO) AS THIS HIGH LATITUDE FEATURE
ALSO SUPPORTS THE ADVECTION OF ANOMALOUSLY COLD AIR INTO MANY PARTS OF THE
CENTRAL AND EASTERN CONUS DURING EARLY MAY. OVER TIME, ENSEMBLES GENERALLY
MAINTAIN A -NAO CIRCULATION OVER EASTERN NORTH AMERICA TO KEEP COOLER
TEMPERATURES OVER THE EASTERN U.S., HOWEVER THE LATEST GEFS AND ECMWF
SIGNIFICANTLY DISAGREE IN REGARDS TO THE EVOLUTION OF THE MID-LEVEL PATTERN
UPSTREAM OVER WESTERN NORTH AMERICA. THE ECMWF FAVORS AN AMPLIFYING TROUGH
SHIFTING EASTWARD FROM THE GULF OF ALASKA TO FORCE RISING HEIGHTS ACROSS THE
WESTERN CONUS BY THE MIDDLE OF THE PERIOD. IN CONTRAST, THE GEFS LACKS ANY
DEVELOPMENT OF THIS MID-LEVEL FEATURE UPSTREAM, RESULTING IN MORE OF A ZONAL
PATTERN OVER THE INTERIOR WEST WITH A TILT TOWARDS BELOW-NORMAL HEIGHTS
SITUATED JUST OFFSHORE OF THE LOWER WEST COAST. ANY SIGN OF ANOMALOUS TROUGHING
POINTS TO ADDITIONAL SOUTHERN STREAM ENERGY TO PROMOTE MORE UNSETTLED WEATHER
INTO THE WESTERN AND CENTRAL CONUS COMPARED TO THE ECMWF.
TIED TO THE AMPLIFYING 500-HPA TROUGH LATE NEXT WEEK, THE WEATHER PREDICTION
CENTER (WPC) DAY 7 SURFACE ANALYSIS FEATURES A LARGE AREA OF SURFACE HIGH
PRESSURE BECOMING ESTABLISHED OVER THE PLAINS AND MISSISSIPPI VALLEY, WITH A
LARGE COLD FRONT EXTENDING FROM THE SOUTHERN PLAINS TO THE NORTHEAST. OVER THE
PAST FEW DAYS, ENSEMBLE GUIDANCE HAS TRENDED TOWARDS DEVELOPING A MORE
SOUTHERLY AND STRONGER SOLUTION OF THIS MEAN SURFACE HIGH, WHICH IS WELL
REFLECTED IN THE RAW TEMPERATURE TOOLS INDICATING INCREASING CHANCES (NOW >50%)
FOR NEGATIVE TEMPERATURE DEPARTURES FROM THE SOUTHERN PLAINS INTO PARTS OF THE
NORTHEAST. LIKEWISE, PROBABILISTIC EXTREME TOOLS (PETS) FROM THE GEFS AND ECMWF
HAVE ALSO TRENDED COLDER, AND NOW FEATURE 30-50% CHANCES FOR MINIMUM
TEMPERATURES FALLING BELOW THE 15TH PERCENTILE WITH THESE COLD SIGNALS SHIFTING
EASTWARD AND GRADUALLY DECAYING WITH TIME OVER THE SOUTHEASTERN CONUS THROUGH
DAY 11 (MAY 5). WHILE SUBFREEZING TEMPERATURES ARE MOSTLY LIKELY TO BE CONFINED
TO THE NORTHERN PLAINS, UPPER MIDWEST, AND NORTHEAST, THERE CONTINUES TO BE
INCREASED CHANCES IN BOTH THE RAW AND CALIBRATED TOOLS FOR MINIMUM TEMPERATURES
FALLING BELOW 38 AND 40 DEG F REACHING INTO NORTHERN PORTIONS OF THE SOUTHERN
PLAINS, LOWER MISSISSIPPI AND TENNESSEE VALLEYS, AND LOWER MID-ATLANTIC. 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 DUE TO ANTECEDENT
WARMTH THIS SPRING. BASED ON THE COLD TRENDS IN THE TEMPERATURE TOOLS, AND
30-40% CHANCES OF MINIMUM TEMPERATURES APPROACHING NEAR-FREEZING TEMPERATURES
TO ADVERSELY IMPACT EARLY AND SENSITIVE SPRINGTIME VEGETATION OVER THIS REGION
IN CENTRAL AND EASTERN U.S., A MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES
IS INTRODUCED IN THE UPDATED OUTLOOK FOR MAY 2-3. ACCORDING TO THE U.S.
DEPARTMENT OF AGRICULTURE, THERE IS ALSO THE POTENTIAL FOR FREEZE DAMAGE TO
EARLY-MATURING FRUIT CROPS PRIMARILY IN PARTS OF MICHIGAN AND NEW YORK, DESPITE
FREEZING CONDITIONS NOT BEING TOO UNUSUAL IN EARLY MAY. A BROADER SLIGHT RISK
AREA OF MUCH BELOW NORMAL TEMPERATURES REMAINS POSTED, AND IS EXPANDED
SOUTHWARD IN COVERAGE TO ACCOUNT FOR INCREASED CHANCES FOR LOW TEMPERATURES
DIPPING BELOW 40 DEGREES F IN THE PETS EARLY IN THE PERIOD. THE HIGH PRESSURE
SYSTEM REMAINS FAVORED TO MOVE STEADILY EASTWARD, ALLOWING RETURN WARM,
SOUTHERLY FLOW TO DEVELOP OVER THE CENTRAL CONUS FAIRLY QUICKLY. WITH TIME, THE
WARMING TREND WILL PROGRESS EASTWARD, REDUCING AND ENDING THE COLD RISK BY DAYS
10-11.
THE SURFACE HIGH PRESSURE COULD BE ACCOMPANIED BY BREEZY CONDITIONS AS IT PULLS
COLDER AIR SOUTHWARD INTO THE CENTRAL AND EASTERN CONUS. WINDS ARE NOT EXPECTED
TO REACH HAZARDS THRESHOLDS, BUT LARGE PORTIONS OF THIS REGION ARE ENTRENCHED
IN SOME DEGREE OF DROUGHT. THE COMBINATION OF DRY AND BREEZY CONDITIONS OVER
PARTS OF THE CENTRAL AND EASTERN CONUS WHERE THERE IS ANTECEDENT DRYNESS
SIGNIFICANTLY INCREASES THE RISK OF WILDFIRE ACTIVITY, WHICH COULD SPREAD
RAPIDLY. CAUTION SHOULD BE EXERCISED TO MINIMIZE THE CHANCES OF WILDFIRE
IGNITION.
THE AFOREMENTIONED SURFACE RETURN FLOW FAVORED IS EXPECTED TO BRING INCREASED
MOISTURE INTO THE PLAINS AND MISSISSIPPI VALLEY WHERE MULTI-MODEL BASED TOOLS
DEPICT SOME PRECIPITATION RESPONSES BY THE MIDDLE OF WEEK-2. HOWEVER, BOTH RAW
AND CALIBRATED TOOLS ARE MOSTLY UNSUPPORTIVE OF ANY HEAVY PRECIPITATION RISK,
AND GIVEN UNCERTAINTY IN THE EVOLVING PATTERN ALOFT AND AT THE SURFACE UPSTREAM
OVER THE WESTERN CONUS, NO PRECIPITATION RELATED HAZARDS ARE ISSUED 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. 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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