118
FXUS21 KWNC 191831
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 19 2026
SYNOPSIS: A CONTINUATION OF MID-LEVEL CYCLONIC FLOW OVER THE SOUTHWESTERN
CONTIGUOUS U.S. (CONUS) AS WELL AS ENHANCED LOW-LEVEL MOIST, SOUTHERLY FLOW
FROM THE GULF OF AMERICA FROM WEEK-1 INTO EARLY WEEK-2, SUPPORTS A LINGERING
RISK FOR HEAVY PRECIPITATION MAINLY OVER THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY. THE DURATION OF ABOVE-NORMAL PRECIPITATION COUPLED WITH THE
MULTIPLE ROUNDS OF POTENTIALLY HEAVY RAINFALL MAY LEAD TO FLOODING OVER
PORTIONS OF EASTERN TEXAS. MID-LEVEL HIGH PRESSURE FAVORED OVER CANADA IS
EXPECTED TO BRING WELL ABOVE-NORMAL TEMPERATURES FOR THE NORTH-CENTRAL CONUS,
THOUGH ACTUAL TEMPERATURES ARE EXPECTED TO REMAIN BELOW HEAT THRESHOLDS.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY, WED, MAY 27.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE CENTRAL AND SOUTHERN
PLAINS, LOWER AND MIDDLE MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS, SOUTHEAST,
SOUTHERN APPALACHIANS, AND LOWER MID-ATLANTIC, WED-FRI, MAY 27-29.
FLOODING POSSIBLE FOR MUCH OF EASTERN TEXAS, PORTIONS OF ARKANSAS AND LOUISIANA.
DETAILED SUMMARY
FOR FRIDAY MAY 22 - TUESDAY MAY 26:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY MAY 27 - TUESDAY JUNE 02: CONSISTENT WITH PREVIOUS ENSEMBLE MEAN
GUIDANCE, 500-HPA HEIGHT ANOMALY FORECASTS FROM THE GEFS AND ECMWF CONTINUE TO
SHOW DISCREPANCIES IN REGARDS TO THE SHAPE AND STRENGTH OF THE MID-LEVEL
PATTERN TOWARDS THE MIDDLE OF NEXT WEEK. WHILE BOTH MODELS FAVOR AMPLIFIED
RIDGING OVER EASTERN CANADA, THE RESPECTIVE MEAN RIDGE CENTERS ARE DISPLACED
FROM ONE ANOTHER IN THE ANOMALY FIELDS, WITH THE ECMWF FAVORING A MORE WESTERLY
AND MUCH STRONGER MEAN SOLUTION OF THIS FEATURE OVER THE HUDSON BAY. MORE
CRITICALLY, MID-LEVEL HEIGHT ANOMALIES CONTINUE TO BE OF OPPOSITE SIGN
UPSTREAM, WHERE THE ECMWF ENSEMBLE IS RESOLUTE IN FAVORING ANOMALOUS TROUGHING
DIGGING SOUTHWARD INTO THE INTERIOR WEST, WHEREAS THE GEFS MAINTAINS A BROAD
DISTRIBUTION OF POSITIVE HEIGHT DEPARTURES OVER MUCH OF THE WESTERN CONUS
EXTENDING WESTWARD INTO THE NORTHEASTERN PACIFIC. ACROSS THE LOWER LATITUDES,
BETTER AGREEMENT EXISTS BETWEEN THE GEFS AND ECMWF WHERE THERE CONTINUES TO BE
WEAKNESSES IN THE HEIGHT ANOMALIES CHARACTERIZED BY BROAD CYCLONIC FLOW FROM
THE DESERT SOUTHWEST TO THE SOUTHERN PLAINS. ACCOMPANIED BY ENHANCED LOW-LEVEL
SOUTHERLY FLOW FROM THE GULF, THE PATTERN LOOKS TO BE CONDUCIVE FOR
ABOVE-NORMAL, AND POSSIBLY HEAVY PRECIPITATION ACROSS THE SOUTHERN TIER OF THE
U.S. EARLY IN WEEK-2, HOWEVER SIGNIFICANT UNCERTAINTY REMAINS IN THE OUTLOOK AS
A RESULT OF THESE VARIATIONS IN PREDICTED HEIGHT PATTERN ELSEWHERE THROUGHOUT
THE U.S.
BASED ON THE LATEST PRECIPITATION TOOLS, A MODERATE RISK OF HEAVY PRECIPITATION
CONTINUES TO BE DESIGNATED FOR THE SOUTHERN PLAINS AND LOWER MISSISSIPPI
VALLEY, AND REMAINS VALID THROUGH MAY 27. WITHIN THIS HIGHLIGHTED AREA, THE
UNCALIBRATED GEFS AND ECMWF TOOLS FEATURE AT 30-50% CHANCES FOR 3-DAY AMOUNTS
EXCEEDING ONE INCH, WITH THE CALIBRATED PROBABILISTIC EXTREME TOOLS (PETS) ALSO
INDICATING 20-30% CHANCES FOR AMOUNTS EXCEEDING THE 85TH PERCENTILE EARLY IN
THE PERIOD. SURROUNDING THIS MODERATE RISK AREA, A SLIGHT RISK OF HEAVY
PRECIPITATION REMAINS POSTED FROM THE SOUTHERN AND CENTRAL PLAINS EASTWARD TO
PORTIONS OF THE OHIO AND TENNESSEE VALLEYS AND SOUTHEAST, WHERE BOTH GEFS AND
ECMWF PETS SHOW AT LEAST 20% CHANCES FOR AMOUNTS EXCEEDING THE 85TH PERCENTILE
AND 1 INCH THROUGH DAY 10 (MAY 29). RELATIVE TO YESTERDAY, THE SLIGHT RISK AREA
IS EXPANDED EASTWARD TO COVER MORE OF THE SOUTHEAST AND LOWER MID-ATLANTIC
BASED ON WETTER SIGNALS IN THE GEFS PET. THE ECMWF HAS BECOME MORE BULLISH IN
PLACING ELEVATED CHANCES (30-40%) FOR 3-DAY AMOUNTS EXCEEDING AN INCH OVER THE
LOWER EASTERN SEABOARD, HOWEVER GEFS AND CANADIAN FAVORS MORE MID-LEVEL RIDGING
ALOFT, SUPPRESSING THIS HIGHER PRECIPITATION POTENTIAL.
THE RISK OF HEAVY PRECIPITATION HIGHLIGHTED EARLY IN WEEK-2 FOLLOWS AN ACTIVE
PRECIPITATION REGIME OVER THE SOUTH-CENTRAL CONUS DURING WEEK-1. WHILE THIS
PATTERN MAY PROVE TO BE BENEFICIAL IN ALLEVIATING ANTECEDENT DRYNESS AND BRING
IMPROVEMENT TO PREVAILING DROUGHT CONDITIONS, THE DURATION OF ABOVE-NORMAL
PRECIPITATION COUPLED WITH MULTIPLE ROUNDS OF POTENTIALLY HEAVY RAINFALL MAY
TRIGGER FLOODING, AS SOME WATERSHEDS ARE ALREADY BEGINNING TO RISE IN RESPONSE
TO THE LARGE INFLUX OF SURFACE WATER. WEEK-1 QPF FORECASTS FROM THE WEATHER
PREDICTION CENTER DEPICT PRECIPITATION TOTALS EXCEEDING 3-5 INCHES FROM
SOUTHEASTERN TEXAS NORTHEASTWARD INTO PORTIONS OF ARKANSAS AND LOUISIANA, AND
ANY CONTINUED HEAVY PRECIPITATION INTO WEEK-2 SUPPORTS THE POTENTIAL OF RIVER
FLOODING. A FLOODING POSSIBLE HAZARD REMAINS POSTED AND IS EXPANDED IN THE
UPDATED OUTLOOK, HIGHLIGHTING THE HIGHEST POTENTIAL FOR RIVER AND STREAM
FLOODING. HOWEVER, URBAN AND FLASH FLOODING IS POSSIBLE OUTSIDE THIS AREA, AND
CAUTION SHOULD ALWAYS BE EXERCISED WHEN APPROACHING FLOODWATER.
TIED TO THE AMPLIFIED RIDGE CENTER OVER CANADA, ENSEMBLES MAINTAIN A BROAD
COVERAGE OF POSITIVE HEIGHT DEPARTURES SUPPORTIVE OF ABOVE-NORMAL TEMPERATURES
OVER MUCH OF NORTH-CENTRAL AND NORTHEASTERN CONUS THROUGHOUT THE PERIOD. BASED
ON RAW TOOLS, THE STRONGEST POSITIVE TEMPERATURE DEPARTURES ARE FAVORED IN
PROXIMITY TO THE ANOMALOUS RIDGE CENTER OVER THE UPPER MIDWEST. PETS CONTINUE
TO HIGHLIGHT INCREASED CHANCES FOR DAYTIME TEMPERATURES EXCEEDING THE 85TH
PERCENTILE, WITH THE ECMWF PET REMAINING MORE BULLISH, DEPICTING 30-40% CHANCES
FOR EXCEEDING THIS CLIMATOLOGICAL THRESHOLD FOCUSED OVER THE NORTHERN PLAINS,
UPPER MISSISSIPPI VALLEY, AND NORTHERN GREAT LAKES FOR MOST OF THE WEEK-2
PERIOD. THESE STRONGER WARM SIGNALS IN THE ECMWF PETS ARE LIKELY DUE TO THE
STRONGER RIDGING FAVORED OVER THE HUDSON BAY. BUT REGARDLESS OF THESE
DIFFERENCES IN THE PETS, THERE IS LITTLE TO NO SIGNAL IN THE TOOLS FOR ACTUAL
TEMPERATURES REACHING ABOVE 90 DEG F TO DRIVE HIGHER HEAT INDEX VALUES OVER
THIS PART OF THE COUNTRY, PRECLUDING ANY CORRESPONDING HEAT HAZARDS. EVEN WITH
THE LOW RISK FOR HEAT, THE NORTHERN PLAINS IS BEING MONITORED FOR A POTENTIAL
RAPID ONSET DROUGHT (ROD) GIVEN THE PREVAILING WARMTH EXPECTED COMBINED WITH
ANTECEDENT DRYNESS. SOIL MOISTURE PERCENTILES ARE RUNNING QUITE LOW FROM
EASTERN MONTANA TO NORTH DAKOTA, WHERE ANY CONTINUED DEARTH OF RAINFALL COULD
WORSEN DRYNESS, ABETTED BY THE ABOVE-NORMAL TEMPERATURES TO ELEVATE
EVAPOTRANSPIRATION RATES. HOWEVER, THERE CONTINUES TO BE A NUMBER OF
PRECIPITATION TOOLS THAT FAVOR A TILT TOWARDS ABOVE-NORMAL PRECIPITATION DURING
WEEK-2 TO ALLAY ANY ROD RISK AT THIS TIME.
THE STRONGER MEAN MID-LEVEL TROUGH THAT IS FAVORED TO SHIFT EASTWARD FROM THE
NORTHEASTERN PACIFIC IN THE ECMWF ENSEMBLE SUPPORTS THE POTENTIAL FOR HIGH
WINDS ACROSS PORTIONS OF THE WEST COAST, AS WELL AS ACROSS PARTS OF THE
INTERIOR WEST AND HIGH PLAINS ASSOCIATED WITH ADDITIONAL SHORTWAVE ENERGY.
WHILE THIS POTENTIAL IS REFLECTED IN BOTH RAW AND CALIBRATED WIND TOOLS FROM
THE ECMWF, THE RIDGING FAVORED IN THE GEFS RESULTS IN LOWERED WIND RISK, AND NO
CORRESPONDING WIND HAZARDS ARE ISSUED FOR WEEK-2.
IN ALASKA, RIVER ICE BREAKUP SEASON IS NOW WELL UNDERWAY. PARTS OF THE MIDDLE
OR LOWER YUKON ARE CURRENTLY PARTIALLY OPEN, BUT ARE EXPECTED TO BE CLEAR BY
THE WEEK-2 PERIOD. HOWEVER, THE THREAT OF ICE JAM FLOODING WOULD MOST LIKELY BE
ALONG RIVERS NORTH OF THE ARCTIC CIRCLE AS THEY ARE CURRENTLY MOSTLY ICE. RIVER
BREAKUP FLOODING CAN OCCUR WITH LITTLE OR NO NOTICE AS CONDITIONS ON FROZEN
RIVERS CAN CHANGE QUICKLY, SO PLEASE CHECK WITH THE ALASKA PACIFIC RIVER
FORECAST CENTER FOR THE LATEST CONDITIONS AND ADVISORIES.
FORECASTER: NICK NOVELLA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
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