399
FXUS21 KWNC 051805
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 05 2026
SYNOPSIS: AMPLIFIED MID-LEVEL HIGH PRESSURE IS FORECAST ACROSS THE WESTERN
CONTIGUOUS U.S. (CONUS) LATE IN WEEK-1. BY THE START OF THE WEEK-2 PERIOD, THIS
FEATURE IS PREDICTED TO WEAKEN AND SHIFT EASTWARD TOWARD THE SOUTH-CENTRAL
CONUS. THIS RESULTS IN RELATIVELY LOWER CHANCES FOR EXTREME HEAT ACROSS THE
SOUTHWEST COMPARED TO YESTERDAY, BUT WITH INCREASING HEAT CONCERNS ACROSS THE
SOUTHERN PLAINS, PARTICULARLY OVER PARTS OF NORTHWESTERN TEXAS INTO OKLAHOMA
WHERE RECORD BREAKING TEMPERATURES FOR THIS TIME OF YEAR ARE POSSIBLE.
CONVERSELY, PERSISTENT MID-LEVEL LOW PRESSURE ACROSS THE GREAT LAKES AND
NORTHEAST FAVORS ANOMALOUSLY COOL WEATHER ACROSS THE REGION AT THE OUTSET OF
THE PERIOD.
HAZARDS
MODERATE RISK OF EXTREME HEAT ACROSS NORTHWESTERN TEXAS INTO OKLAHOMA, WED-THU,
MAY 13-14.
SLIGHT RISK OF EXTREME HEAT ACROSS PORTIONS OF THE SOUTHERN PLAINS EXTENDING
INTO SOUTHERN KANSAS, WED-FRI, MAY 13-15.
SLIGHT RISK OF EXTREME HEAT ACROSS PORTIONS OF THE SOUTHWESTERN CONUS AND THE
CALIFORNIA CENTRAL VALLEY, WED-FRI, MAY 13-15.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE GREAT
LAKES, OHIO VALLEY, APPALACHIANS, AND NORTHEAST, WED, MAY 13.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS,
WED-THU, MAY 13-14.
SLIGHT RISK OF HIGH WINDS ACROSS THE NORTHERN COAST OF CALIFORNIA AND COASTAL
OREGON, WED-FRI, MAY 13-15.
DETAILED SUMMARY
FOR FRIDAY MAY 08 - TUESDAY MAY 12:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY MAY 13 - TUESDAY MAY 19: THE 0Z ECMWF, GEFS, AND CANADIAN
ENSEMBLES DEPICT A STRONG MID-LEVEL RIDGE (+120 METER POSITIVE HEIGHT ANOMALY)
OVER THE WESTERN CONUS LATE IN WEEK-1. BY THE OUTSET OF WEEK-2, THIS RIDGE IS
FORECAST TO WEAKEN AND SHIFT FARTHER EASTWARD INTO THE SOUTH-CENTRAL CONUS.
THIS FAVORS THE GREATEST HEAT RISK POTENTIAL ALSO SHIFTING FROM THE SOUTHWEST
TO THE SOUTHERN PLAINS. AS A RESULT, THE MODERATE RISKS OF EXTREME HEAT ARE
DISCONTINUED ACROSS THE CALIFORNIA CENTRAL VALLEY AND DESERT SOUTHWEST, WITH A
SLIGHT RISK CONTINUING THROUGH MAY 15 AS HIGH TEMPERATURES MAY STILL REACH THE
UPPER 90S DEG F TO OVER 100 DEG F, BUT WOULD BE RELATIVELY COOLER COMPARED TO
PRIOR DAYS. THE NATIONAL BLEND OF MODELS (NBM) AND UNCALIBRATED DYNAMICAL
MODELS NOW DEPICT THE POTENTIAL FOR RECORD DAILY HIGH TEMPERATURES ACROSS
NORTHWESTERN TEXAS INTO WESTERN AND CENTRAL OKLAHOMA AND SOUTHERN KANSAS. THE
HOTTEST AREAS MAY SEE HIGHS IN THE UPPER 90S TO NEAR 100 DEG F, WITH
INDICATIONS OF RECORD HEAT BEGINNING PRIOR TO THE START OF THE PERIOD. THE GEFS
AND ECMWF PROBABILISTIC EXTREMES TOOLS (PETS) DEPICT AT LEAST A 40 PERCENT
CHANCE MAXIMUM TEMPERATURES EXCEED THE 85TH CLIMATOLOGICAL PERCENTILE ACROSS
PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS EARLY IN THE PERIOD, AND SKILL
WEIGHTED CALIBRATED HEAT RISK GUIDANCE ALSO INDICATES PROBABILITIES OF 40-60
PERCENT FOR HEAT TO EXCEED THE 90TH CLIMATOLOGICAL PERCENTILE. A MODERATE RISK
OF EXTREME HEAT IS POSTED ACROSS NORTHWESTERN TEXAS INTO PARTS OF OKLAHOMA MAY
13-14 WHERE THERE IS THE GREATEST POTENTIAL FOR TEMPERATURES ABOVE 95 DEG F.
THE SLIGHT RISK IS VALID THROUGH MAY 15, AND IS EXTENDED FARTHER NORTH INTO
SOUTHERN KANSAS WHERE TEMPERATURES MAY REACH 90 DEG F. ELEVATED HEAT RISK
SIGNALS ALSO SUPPORT AN EXTENSION OF THE SLIGHT RISK INTO THE RIO GRANDE VALLEY
DUE TO ENHANCED MOISTURE AND POTENTIAL FOR ELEVATED HEAT INDEX VALUES.
THE ANOMALOUS WARMTH FORECAST ACROSS THE WEST FAVORS THERMAL LOW DEVELOPMENT
AND AN INCREASED PRESSURE GRADIENT ALONG PARTS OF THE WEST COAST. THE
UNCALIBRATED 0Z GEFS AND ECMWF ENSEMBLES BOTH SHOW ENHANCED PROBABILITIES FOR
WIND SPEEDS ABOVE 25-MPH ACROSS COASTAL PORTIONS OF NORTHERN CALIFORNIA AND
OREGON EARLY IN WEEK-2, AND THIS SIGNAL IS ALSO APPARENT IN THE PETS.
THEREFORE, A SLIGHT RISK OF HIGH WINDS IS POSTED ACROSS THESE AREAS, MAY 13-15.
MODELS ALSO DEPICT ELEVATED CHANCES FOR GUSTY WINDS ACROSS THE SOUTH-CENTRAL
CONUS, AND THIS IS PARTICULARLY CONCERNING GIVEN THE EXTREME HEAT POTENTIAL
COMBINED WITH DRY SOILS CONTRIBUTING TO AN ENHANCED WILDFIRE THREAT. THIS
SUPPORTS A SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE CENTRAL AND
SOUTHERN PLAINS, MAY 13-14.
A PERSISTENT TROUGH LINKED TO THE NEGATIVE PHASE OF THE NORTH ATLANTIC
OSCILLATION (-NAO) REMAINS FORECAST ACROSS THE GREAT LAKES AND NORTHEAST AT THE
START OF WEEK-2. THIS CONTINUES TO FAVOR BELOW-NORMAL TEMPERATURES ACROSS THE
REGION. DESPITE IT GETTING LATER INTO MAY, THE ECMWF AND GEFS PETS DEPICT PARTS
OF THE OHIO VALLEY, GREAT LAKES, APPALACHIANS, AND NORTHEAST HAVING AT LEAST A
20 PERCENT CHANCE MINIMUM TEMPERATURES FALL BELOW THE 15TH CLIMATOLOGICAL
PERCENTILE AND 40 DEG F ON DAY-8 (MAY 13). LATE SEASON FROSTS STILL CANNOT BE
RULED OUT ACROSS MORE NORTHERN AND HIGHER ELEVATION AREAS, AND THE SLIGHT RISK
FOR MUCH BELOW NORMAL TEMPERATURES REMAINS IN PLACE, MAY 13. A MORE SOUTHERLY
COMPONENT TO THE SURFACE FLOW COMBINED WITH A WARMING CLIMATOLOGY FAVORS
INCREASING TEMPERATURES THEREAFTER.
AS A RESULT OF THE MORE SOUTHERLY FLOW PATTERN EMERGING, THE 0Z ECMWF ENSEMBLE
DEPICTS ENHANCED PRECIPITATION CHANCES ACROSS THE EAST-CENTRAL CONUS EARLY IN
THE PERIOD, WITH ITS CORRESPONDING PET SHOWING A FAIRLY BROAD AREA WITH AT
LEAST 20 PERCENT CHANCES FOR 3-DAY PRECIPITATION TOTALS TO EXCEED THE 85TH
CLIMATOLOGICAL PERCENTILE AND 1-INCH EXTENDING FROM THE GULF COAST NORTH TO THE
MIDDLE MISSISSIPPI AND OHIO VALLEYS. HOWEVER, SUPPORT FROM THE GEFS IS LIMITED,
AND GIVEN THE MODEL UNCERTAINTY NO RELATED PRECIPITATION HAZARD IS ISSUED. THIS
WILL CONTINUE TO BE MONITORED, BUT THIS SURFACE EVOLUTION WOULD REDUCE ANY RISK
FOR HAZARDOUS COLD TEMPERATURES ACROSS THE OHIO VALLEY AND NORTHEAST.
OVER THE ALASKA REGION, SURFACE LOW PRESSURE ACROSS THE BERING SEA FAVORS
INCREASED SOUTHERLY FLOW AND OCCASIONAL ENHANCED PRECIPITATION AND GUSTY WINDS
ALONG THE SOUTHERN AND SOUTHEAST COASTS. HOWEVER, HAZARDS CRITERIA ARE NOT
ANTICIPATED TO BE REACHED. TROUGHING FAVORS GENERALLY NEAR- TO SLIGHTLY
BELOW-NORMAL TEMPERATURES OVER MOST OF THE STATE, EXCLUDING THE NORTHWESTERN
MAINLAND WHERE THERE ARE ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES. 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: THOMAS COLLOW
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