043
FXUS21 KWNC 151812
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 15 2026
SYNOPSIS: MID-LEVEL LOW PRESSURE FORECAST OVER THE WESTERN CONTIGUOUS U.S.
(CONUS) AND ASSOCIATED LEE CYCLOGENESIS SUPPORTS THE POTENTIAL FOR EPISODES OF
HIGH WINDS, HIGH ELEVATION HEAVY SNOW, ALONG WITH AN ELEVATED RISK OF HEAVY
PRECIPITATION FOCUSED OVER THE LOWER AND MIDDLE MISSISSIPPI VALLEY EARLY IN
WEEK-2. THE FAVORED EASTWARD EXPANSION OF THE HEAVY PRECIPITATION RISK IS
EXPECTED TO PROVIDE RELIEF FOR MANY MOISTURE STARVED PORTIONS OF THE SOUTHEAST.
OVER THE UPPER MIDWEST, FLOODING IS POSSIBLE ASSOCIATED WITH PERSISTENT NEAR TO
ABOVE-NORMAL PRECIPITATION ACCELERATING SPRING SNOWMELT OVER THE NEXT TWO
WEEKS.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHERN PLAINS,
MIDDLE AND LOWER MISSISSIPPI, TENNESSEE AND OHIO VALLEYS, THU-FRI, APR 23-24.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE EASTERN GREAT PLAINS,
MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS, APPALACHIANS, AND SOUTHEAST, THU-SUN,
APR 23-26.
SLIGHT RISK OF HEAVY SNOW FOR THE CENTRAL ROCKIES, THU-SAT, APR 23-25.
SLIGHT RISK OF HIGH WINDS FOR PARTS OF THE GREAT BASIN, SOUTHWEST, ROCKIES,
GREAT PLAINS, AND MISSISSIPPI VALLEY, THU-SAT, APR 23-25.
POSSIBLE FLOODING FOR PARTS OF THE GREAT LAKES REGION AND UPPER AND MIDDLE
MISSISSIPPI VALLEY.
DETAILED SUMMARY
FOR SATURDAY APRIL 18 - WEDNESDAY APRIL 22:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY APRIL 23 - WEDNESDAY APRIL 29: DURING WEEK-2, DYNAMICAL MODELS
CONTINUE TO FEATURE A TRANSIENT 500-HPA HEIGHT PATTERN, WITH THE PERIOD
STARTING OFF WITH ANOMALOUS TROUGHING FAVORED ACROSS THE SOUTHWESTERN CONUS AND
A DEAMPLIFYING RIDGE MAINLY EAST OF THE MISSISSIPPI. OVER THE PAST FEW DAYS,
BOTH THE GEFS AND ECMWF ENSEMBLES DEPICT A MORE AMPLIFIED AND DEEPER MEAN
SOLUTION OF THIS FORMER MID-LEVEL FEATURE BY LATER NEXT WEEK, WHERE ASSOCIATED
SURFACE LOW DEVELOPMENT IN THE LEE OF THE ROCKIES, COMBINED WITH AMPLE RETURN
FLOW FROM THE GULF, IS ANTICIPATED TO BRING A PERIOD OF UNSETTLED WEATHER FOR
MUCH OF THE CENTRAL THIRD OF THE CONUS. MEANWHILE, ENSEMBLES CONTINUE TO FAVOR
THE DEVELOPMENT OF AN AMPLIFIED RIDGE CENTERED NEAR THE DAVIS STRAIT CONSISTENT
WITH A TRANSITION TOWARDS A NEGATIVE NORTH ATLANTIC OSCILLATION (-NAO)
CIRCULATION. THIS PATTERN SHIFT MAY BE IN RESPONSE TO A HIGH AMPLITUDE
MADDEN-JULIAN OSCILLATION (MJO) UNFOLDING IN THE TROPICAL WESTERN PACIFIC. WITH
THE POTENTIAL FOR HIGHER LATITUDE BLOCKING BECOMING ESTABLISHED ACROSS CANADA,
ENSEMBLE GUIDANCE IS INCREASINGLY FAVORING MORE NEGATIVE HEIGHT DEPARTURES
OVERSPREADING MUCH OF THE CONUS, AND FEATURE A PAIR OF MEAN NEGATIVE HEIGHT
ANOMALY CENTERS OVER THE SOUTHWESTERN AND NORTHEASTERN CONUS LATER IN WEEK-2.
AS A RESULT, THIS IS ANTICIPATED TO PROMOTE A PREDOMINANTLY COOLER PATTERN FOR
MANY PARTS OF THE CONUS TOWARDS LATE APRIL.
TIED TO THE STRONGER MID-LEVEL TROUGHING OVER THE SOUTHWESTERN CONUS EARLY IN
WEEK-2, BOTH THE GEFS AND ECMWF ENSEMBLES CONTINUE TO FEATURE SURFACE LOW
DEVELOPMENT OVER WESTERN NEBRASKA AND WESTERN KANSAS, WITH A DEEPER MEAN LOW
(NOW SUB 1000-HPA) COMPARED TO YESTERDAY. WITH AMPLE LOWER-LEVEL MOISTURE
ADVECTION AHEAD OF THE MEAN LOW, THE HIGHEST PRECIPITATION AMOUNTS REMAIN
PRIMARILY FAVORED OVER THE LOWER AND MIDDLE MISSISSIPPI VALLEY. A MODERATE RISK
OF HEAVY PRECIPITATION REMAINS POSTED FOR THIS PART OF THE COUNTRY FOR APR
23-24 AND IS SLIGHTLY EXPANDED WHERE THE UNCALIBRATED GEFS AND ECMWF SHOW AT
LEAST 40% CHANCES OF 3-DAY AMOUNTS EXCEEDING ONE INCH EARLY IN WEEK-2. SIMILAR
TO PREVIOUS GUIDANCE, THE ECMWF CONTINUES TO DEPICT A MORE SOUTHEASTERLY
EXTENSION OF THE HEAVY PRECIPITATION POTENTIAL INTO THE SOUTHEAST WHICH IS
LIKELY DUE TO A FASTER EROSION OF THE RIDGING ALOFT COMPARED TO THE GEFS EARLY
IN WEEK-2. WHILE THIS DOES ADD TO UNCERTAINTY IN THE OUTLOOK, THE UNCALIBRATED
GEFS DOES SHOW AN UPTICK IN THE HEAVY PRECIPITATION SIGNALS OVER THE SOUTHEAST
A BIT LATER IN THE PERIOD, AND THEREFORE THE ENVELOPING SLIGHT RISK AREA OF
HEAVY PRECIPITATION IS AGAIN EXPANDED EASTWARD TO COVER MORE OF MISSISSIPPI,
ALABAMA, AND GEORGIA IN THE UPDATED OUTLOOK, AND VALID THROUGH APR 26. THE
ADJUSTED SLIGHT RISK COVERAGE IS ALSO CONSISTENT WITH BOTH THE GEFS AND ECMWF
PROBABILISTIC EXTREME TOOLS (PETS) WHICH INDICATE AT LEAST 20% CHANCES FOR
3-DAY AMOUNTS EXCEEDING THE 85TH PERCENTILE THROUGH THE MIDDLE OF WEEK-2.
WITHIN THE HIGHLIGHTED HEAVY PRECIPITATION RISK AREAS, THERE IS A THREAT OF
THUNDERSTORM ACTIVITY, WHERE DETERMINISTIC SOLUTIONS SHOW DEWPOINTS REACHING
THE UPPER 60S AND LOWER 70S (DEG F). GIVEN THIS EXPANDED HEAVY PRECIPITATION
RISK INTO THE SOUTHEAST, THE RAPID ONSET DROUGHT (ROD) RISK IS REMOVED IN THE
UPDATED OUTLOOK. DESPITE WEEK-1 REMAINING VERY DRY AND WARM, THERE IS GROWING
SUPPORT IN THE PREDICTED 14-DAY PRECIPITATION ANOMALIES FLIPPING SIGN OVER THE
SOUTHEAST DUE TO THIS HEAVY PRECIPITATION RISK, AS ANY ENHANCED PRECIPITATION
IS EXPECTED TO MITIGATE ANTECEDENT DRYNESS IN THE REGION.
UPSTREAM OF THE MEAN SURFACE LOW, THERE IS BETTER MODEL SUPPORT FOR
ACCUMULATING SNOWFALL OVER THE HIGHER ELEVATIONS OF THE CENTRAL ROCKIES.
ALTHOUGH THE UNCALIBRATED GEFS FEATURES LOW PROBABILITIES FOR HEAVY SNOW, ITS
CALIBRATED SNOW WATER EQUIVALENT (SWE) COUNTERPART INDICATES AT LEAST 20%
CHANCES FOR VALUES EXCEEDING THE 85TH PERCENTILE, WITH THE UNCALIBRATED ECMWF
DEPICTING AT LEAST 20-50% CHANCES FOR 3-DAY SNOWFALL AMOUNTS EXCEEDING 6
INCHES. THEREFORE, A SLIGHT RISK OF HEAVY SNOW IS POSTED OVER THE FRONT RANGE
OF COLORADO AND INTO THE PARTS OF WYOMING. THE FAVORED ANOMALOUS TROUGHING ALSO
SUPPORTS AN INCREASED RISK OF PERIODS OF ELEVATED WINDS DURING WEEK-2. A BROAD
SLIGHT AREA OF HIGH WINDS REMAINS ISSUED FOR THE HIGHER ELEVATIONS OF THE
INTERIOR WEST EASTWARD TO THE MISSISSIPPI VALLEY (APR 23-25) WHERE UNCALIBRATED
TOOLS SHOW INCREASED CHANCES FOR WIND GUSTS EXCEEDING 34KTS (~40MPH) THROUGH
THE MIDDLE OF THE WEEK-2. A CORRESPONDING MODERATE RISK AREA WAS CONSIDERED
OVER THE SOUTHERN ROCKIES AND SOUTHERN PLAINS AHEAD OF THE MEAN TROUGH AXIS AND
WHERE HIGHER PROBABILITIES OF EXCEEDANCE ARE INDICATED IN THE RAW TOOLS,
HOWEVER, PET GUIDANCE REMAINS LESS SUPPORTIVE OF THIS HIGHER RISK DESIGNATION.
WITH ABOVE-NORMAL SNOWPACK AND ABOVE-NORMAL PRECIPITATION BEING REGISTERED FOR
MUCH OF THE GREAT LAKES, SEASONAL SPRING MELT HAS LED TO SATURATED SOILS AS
WELL AS WIDESPREAD RIVER FLOODING, THUS ANY ADDITIONAL WATER IN THE RIVER
SYSTEMS WILL NOT BE EASILY ACCOMMODATED. MUCH OF THE GREAT LAKES REMAINS
FAVORED FOR NEAR TO ABOVE-NORMAL PRECIPITATION DURING THE NEXT TWO WEEKS, WHICH
COULD RESULT IN ACCELERATED SNOW MELT EXACERBATING THE FLOODING POTENTIAL. A
FLOODING POSSIBLE HAZARD IS POSTED FOR PARTS OF THE GREAT LAKES REGION AND
UPPER AND MIDDLE MISSISSIPPI VALLEY, WHERE THE CONFLUENCE OF THESE PARAMETERS
IS GREATEST. HOWEVER, THE THREAT OF FLOODING IS NOT LIMITED TO THESE AREAS
ALONE, AS LINGERING SNOW REMAINS ON THE GROUND OVER PORTIONS OF THE HIGH PLAINS
AS WELL. NO HAZARD IS ISSUED FOR THE RED RIVER OF THE NORTH OR OTHER
WATERCOURSES IN THE REGION, ALTHOUGH RIVER RISES ARE LIKELY AS SNOW MELTS AND
LOCALIZED FLOODING MAY OCCUR.
NO HAZARDS ARE ISSUED OVER ALASKA, BUT FLOODING CAN OCCUR THIS TIME OF YEAR
WITH LITTLE OR NO NOTICE DURING RIVER ICE BREAKUP SEASON. THE COLDER
TEMPERATURES IN THE WEEK-2 OUTLOOK INCREASE THE CHANCES OF DELAYED RIVER
BREAKUP IN ALASKA AND INCREASE THE CHANCES OF ICE JAM FLOODING. CHECK THE
ALASKA PACIFIC RIVER FORECAST CENTER (HTTPS://WWW.WEATHER.GOV/APRFC/BREAKUPMAP)
FOR THE LATEST CONDITIONS OR ADVISORIES.
FORECASTER: NICK NOVELLA
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