957
FXUS21 KWNC 031849
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 03 2025
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS FORECAST TO WEAKEN ACROSS THE WESTERN
CONTIGUOUS U.S. (CONUS) LATE IN WEEK-1 AND BE REPLACED BY A MID-LEVEL TROUGH
EARLY IN WEEK-2. AS A RESULT, INCREASED CHANCES FOR EXTREME HEAT ARE FAVORED
ACROSS LOWER ELEVATIONS OF THE GREAT BASIN AND CALIFORNIA CENTRAL VALLEY LATE
IN WEEK-1 AND INTO THE START OF WEEK-2, COINCIDENT WITH THE STRONGEST HEAT
SIGNALS IN THE GUIDANCE. TEMPERATURES ARE FORECAST TO TREND DOWNWARD DURING THE
EARLY AND MIDDLE PORTIONS OF WEEK-2, AS MID-LEVEL LOW PRESSURE BECOMES BRIEFLY
ESTABLISHED ACROSS THE WEST. FRONTAL ACTIVITY ACROSS THE MIDWEST AND A
POTENTIAL INCREASE IN TROPICAL MOISTURE ACROSS THE SOUTHEAST SUPPORTS INCREASED
CHANCES FOR HEAVY PRECIPITATION, BUT MODEL DIFFERENCES RESULT IN ONLY A SLIGHT
RISK BEING HIGHLIGHTED OVER A LARGE AREA. MODELS ARE IN BETTER AGREEMENT
REGARDING BROAD RIDGING DEVELOPING OVER THE EASTERN HALF OF THE CONUS DURING
THE SECOND HALF OF WEEK-2, FAVORING INCREASING EXTREME HEAT RISK ACROSS PARTS
OF THE MIDWEST AND MID-ATLANTIC.
HAZARDS
SLIGHT RISK OF EXTREME HEAT ACROSS THE CALIFORNIA CENTRAL VALLEY AND LOWER
ELEVATIONS OF THE GREAT BASIN, WED, JUN 11.
SLIGHT RISK OF EXTREME HEAT ACROSS PORTIONS OF THE MIDWEST, THU-TUE, JUN 12-17.
SLIGHT RISK OF EXTREME HEAT ACROSS PORTIONS OF THE MID-ATLANTIC, THU-TUE, JUN
12-17.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE GREAT PLAINS,
MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, GREAT LAKES, SOUTHERN APPALACHIANS,
AND SOUTHEAST, WED-SAT, JUN 11-14.
DETAILED SUMMARY
FOR FRIDAY JUNE 06 - TUESDAY JUNE 10:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JUNE 11 - TUESDAY JUNE 17: ANOMALOUS MID-LEVEL RIDGING IS
PREDICTED TO BEGIN WEAKENING EARLY IN WEEK-2 AND BECOME REPLACED BY TROUGHING.
AS A RESULT, SIGNIFICANT HEAT SIGNALS ACROSS THE WESTERN CONUS LATE IN WEEK-1
WILL PERSIST INTO EARLY WEEK-2, FOLLOWED BY COOLER AIR BEGINNING TO WORK ITS
WAY SOUTHWARD ACROSS THE WEST. THE ECENS AND GEFS PROBABILISTIC EXTREMES TOOLS
(PETS) DEPICT AT LEAST A 20 PERCENT CHANCE OF MAXIMUM TEMPERATURES EXCEEDING
THE 85TH CLIMATOLOGICAL PERCENTILE ON DAY-8 (JUN 11), WITH A DECREASING TREND
THEREAFTER. MAXIMUM TEMPERATURES IN THE UNCALIBRATED 0Z ECENS AND GEFS ARE
PREDICTED TO BE IN THE 90S DEG F ACROSS LOWER ELEVATIONS OF THE GREAT BASIN,
AND INTO THE LOW 100S DEG F OVER PARTS OF THE CALIFORNIA CENTRAL VALLEY AT THE
START OF THE PERIOD. GIVEN THE FORECAST DECREASE IN THE MAGNITUDE OF POSITIVE
HEIGHT ANOMALIES AND THE RESULTANT DOWNWARD TEMPERATURE TREND, THE SLIGHT RISK
FOR EXTREME HEAT IS VALID FOR DAY-8 (JUN 11) ONLY.
SURFACE HIGH PRESSURE OFF THE ATLANTIC COAST WILL HELP TO ADVECT MOIST,
UNSTABLE AIR FROM THE GULF AND SOUTHWEST ATLANTIC ACROSS THE SOUTHEASTERN
CONUS, THE GREAT PLAINS, AND THE MISSISSIPPI VALLEY. THE PETS AND UNCALIBRATED
TOOLS CONTINUE TO SUPPORT A BROAD SLIGHT RISK FOR HEAVY PRECIPITATION, JUN
11-14, ACROSS THESE REGIONS TIED TO FRONTAL ACTIVITY AND OCCASIONAL CONVECTIVE
PRECIPITATION. MUCH OF THE SOUTHEASTERN QUADRANT OF THE LOWER 48 STATES HAS
SEEN A SURPLUS IN PRECIPITATION DURING THE LAST 30 DAYS AND ANOMALOUSLY WET
SOILS. THEREFORE, EVEN THOUGH NO FLOOD SHAPE IS DRAWN ON TODAY’S MAP, LOCALIZED
FLOODING IS A CONCERN FOR ANY AREAS THAT DO RECEIVE HEAVY RAINFALL.
BY JUNE 12TH (DAY 9), THE 0Z ECENS, GEFS, AND CMCE ARE COMING INTO BETTER
AGREEMENT DEPICTING A BROAD 588-DM RIDGE DEVELOPING OVER THE EASTERN CONUS.
THIS PATTERN IS INDICATIVE OF A WIDESPREAD HEAT EVENT TAKING SHAPE BY MID JUNE,
WITH SOME EVIDENCE OF THIS IN THE ECENS PET WHICH DEPICTS AN EXPANDING AREA OF
AT LEAST A 20 PERCENT CHANCE MAXIMUM TEMPERATURES EXCEED 90 DEG F ACROSS THE
MIDWEST. WHILE TEMPERATURES IN THE UNCALIBRATED ENSEMBLE GUIDANCE ARE GENERALLY
NOT TOO IMPRESSIVE YET, DEW POINTS ARE FORECAST TO INCREASE WHICH WILL LEAD TO
HIGHER HEAT INDEX VALUES. FOR NOW A SLIGHT RISK OF EXTREME HEAT IS POSTED
ACROSS THE CORN BELT AND MOST OF THE OHIO VALLEY, JUN 12-17, BASED MAINLY ON
PATTERN RECOGNITION AND GOOD MODEL AGREEMENT.
A MODERATELY STRONG MID-LEVEL RIDGE AND POSITIVE HEIGHT ANOMALIES ARE FORECAST
OVER ALASKA, WITH THE LARGEST POSITIVE HEIGHT ANOMALIES 150-180 METERS
ABOVE-NORMAL SOUTH OF THE ALASKA PENINSULA. PROBABILITIES FOR ABOVE-NORMAL
PRECIPITATION ARE INCREASED ACROSS THE NORTHERN MAINLAND, BUT NO AREAS ARE
EXPECTED TO REACH HAZARDS THRESHOLDS. BELOW-NORMAL TEMPERATURES DOMINATE MOST
OF THE STATE, EXCEPT OVER SOUTHWESTERN ALASKA, WHERE NEAR TO ABOVE-NORMAL
TEMPERATURES ARE FAVORED. RIVERS ALONG THE NORTH SLOPE ARE STILL LOCKED IN ICE.
RESIDENTS ARE ENCOURAGED TO BE AWARE OF ANY RAPID WARMUP IN TEMPERATURES WHICH
COULD RESULT IN ICE JAMS AND RESULTANT FLOODING.
FORECASTER: ANTHONY ARTUSA
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