031
FXUS21 KWNC 201752
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 20 2025
SYNOPSIS: STRONG MID-LEVEL HIGH PRESSURE IS PREDICTED TO PEAK ACROSS THE
EASTERN CONTIGUOUS U.S. (CONUS) DURING WEEK-1 AND WEAKEN DURING WEEK-2.
INCREASED LIKELIHOOD OF EXTREME HEAT IS PREDICTED TO LINGER AT THE BEGINNING OF
THE PERIOD ACROSS THE NORTHEASTERN CONUS AND PARTS OF THE MID-ATLANTIC, OHIO
VALLEY, AND UPPER SOUTHEAST. THE REMNANTS OF HURRICANE ERICK ALONG WITH A
SURFACE FRONT EXTENDING FROM THE FOUR CORNERS REGION TO THE GREAT LAKES MAY
BRING LOCALIZED HEAVY PRECIPITATION TO PARTS OF THE FOUR CORNERS AND UPPER
MIDWEST EARLY IN WEEK-2. A TIGHT PRESSURE GRADIENT IS PREDICTED TO FORM OVER
MUCH OF COASTAL CALIFORNIA AND SOUTHERN OREGON, SUPPORTING EPISODES OF HIGH
WINDS ACROSS THESE AREAS FROM THE BEGINNING TO MIDDLE OF WEEK-2.
HAZARDS
SLIGHT RISK OF EXTREME HEAT FOR PORTIONS OF THE EASTERN CONUS, SAT-SUN, JUN
28-29.
SLIGHT RISK OF EPISODIC HIGH WINDS ACROSS COASTAL PORTIONS OF CENTRAL AND
NORTHERN CALIFORNIA AND SOUTHWESTERN OREGON, SAT-TUE, JUN 28-JUL 1.
DETAILED SUMMARY
FOR MONDAY JUNE 23 - FRIDAY JUNE 27:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY JUNE 28 - FRIDAY JULY 04: MULTIPLE ENSEMBLE MEANS SHOW SUBSTANTIAL
MID-LEVEL RIDGING THAT PEAKS DURING WEEK-1 ACROSS THE EASTERN CONUS, THEN
GRADUALLY WEAKENS DURING WEEK-2 WHILE DRIFTING EASTWARD. THIS LEADS TO
DECREASING EXTREME HEAT SIGNALS DURING WEEK-2 ALTHOUGH ENHANCED POTENTIAL FOR
TEMPERATURES ABOVE HAZARDS THRESHOLDS SHOULD LINGER INTO THE PERIOD. AS A
RESULT, A SLIGHT RISK FOR EXTREME HEAT IS POSTED FOR A LARGE PART OF THE
EASTERN CONUS EARLY IN THE PERIOD. NOTE THAT THE LATEST OPERATIONAL EUROPEAN
MODEL BRINGS EXTREME HEAT SOUTHWARD INTO SOUTH CAROLINA AND ADJACENT GEORGIA,
BUT THE PREPONDERANCE OF GUIDANCE FAVORS SLIGHTLY LESS OPPRESSIVE HEAT THERE,
THUS NO HAZARD IS POSTED.
FARTHER WEST, A POTENT MID-LEVEL RIDGE IS EXPECTED TO TRAVERSE FROM THE FAR
WEST EASTWARD INTO THE NORTHERN AND CENTRAL PLAINS. THIS MAY INDUCE AN AREA OF
EXTREME HEAT THAT MOVES EASTWARD DURING THE PERIOD IN CONCERT WITH THE
MID-LEVEL RIDGE. AT THIS TIME, THE PETS ARE UNREMARKABLE, AND MOST OF THE RAW
MODEL OUTPUT KEEPS TEMPERATURES SLIGHTLY BELOW HAZARD THRESHOLDS, SO NO HAZARD
IS POSTED AT THIS TIME. HOWEVER, THE SITUATION NEEDS TO BE MONITORED GIVEN THE
POTENTIAL STRENGTH OF THE MID-LEVEL RIDGE.
THE GEFS, CANADIAN, AND EUROPEAN ENSEMBLES, ALONG WITH OPERATIONAL
DETERMINISTIC MODELS, SHOW THE POSSIBILITY OF SURFACE LOW FORMATION IN THE GULF
WHICH COULD BRING ENHANCED RAINFALL TO PARTS OF THE CENTRAL OR WESTERN GULF
COAST EARLY WEEK-2. HOWEVER, THERE REMAINS HIGH MODEL UNCERTAINTY REGARDING THE
LOCATION, TIMING, AND INTENSITY OF ANY POTENTIALLY HEAVY RAINFALL, SO NO
ASSOCIATED PRECIPITATION HAZARDS CAN BE DESIGNATED AT THIS TIME.
TROPICAL MOISTURE ASSOCIATED WITH THE REMNANTS OF HURRICANE ERICK IS EXPECTED
TO BE PULLED NORTHWARD AND INTERACT WITH A POSSIBLE SURFACE LOW FORMING OVER
THE SOUTHWEST. THIS SETUP FAVORS LOCALIZED ENHANCED RAINFALL AND THUNDERSTORMS
ACROSS THE SOUTHERN HIGH PLAINS AND ROCKIES. AT THIS TIME, IT APPEARS THAT THE
STORM COMPLEX WILL BE NORTHEAST OF THE REGION AND CONSIDERABLY WEAKER BEFORE
WEEK-2 STARTS, SO NO HAZARDS ARE POSTED. HOWEVER, ANY DELAY IN THIS ANTICIPATED
EVOLUTION COULD CAUSE HEAVY RAINFALL AND CONVECTION TO LINGER IN THE SOUTHERN
HIGH PLAINS AND ROCKIES EARLY IN THE PERIOD.
MOISTURE FROM THE REMNANTS OF ERICK MAY CONTINUE EASTWARD AND NORTHEASTWARD,
POSSIBLY INTERACTING WITH A LINGERING SURFACE FRONT LOCATED SOMEWHERE OVER THE
GREAT PLAINS, MISSISSIPPI VALLEY, AND GREAT LAKES. THIS SET-UP FAVORS HEAVY
RAINFALL ACROSS SOME PORTION OF THE CONUS BETWEEN THE ROCKIES AND THE
APPALACHIANS. HOWEVER, THE MODEL SOLUTIONS ARE IN POOR AGREEMENT REGARDING THE
EVOLUTION OF THIS SITUATION, AND THUS THEIR DEPICTIONS VARY WIDELY IN TIMING,
AMOUNT, AND LOCATION OF ANY HEAVY PRECIPITATION. UNTIL THERE IS SOME
CONVERGENCE AMONG THE MODEL SOLUTIONS, NO HEAVY PRECIPITATION HAZARD CAN BE
JUSTIFIED.
SURFACE HIGH PRESSURE OVER THE NORTHEAST PACIFIC ADJACENT TO SURFACE LOW
PRESSURE OVER THE SOUTHWESTERN CONUS MAY LEAD TO TIGHT PRESSURE GRADIENTS ALONG
PORTIONS OF THE WEST COAST. MOST MODEL SOLUTIONS ARE NOT QUITE AS AMPLIFIED
WITH THIS SITUATION AS THEY WERE YESTERDAY, BUT A SLIGHT RISK OF EPISODIC HIGH
WINDS IS STILL JUSTIFIED ALONG THE CENTRAL AND NORTHERN CALIFORNIA COASTLINE,
ALONG WITH EXTREME SOUTHWESTERN OREGON. THIS HAZARD IS IN EFFECT THROUGH JUL 1,
WHEN THE MID-LEVEL PATTERN CHANGES AND THE PRESSURE GRADIENT RELAXES.
ICE-BOUND RIVERS ARE BEGINNING TO BREAK UP IN THE NORTH SLOPE OF ALASKA.
FLOODING IS POSSIBLE BY THE END OF WEEK-1 AND INTO WEEK-2 ACROSS MUCH OF THE
REGION AS A RESULT OF ICE JAMS, AUFEIS, SNOW MELT, AND ASSOCIATED FLOODING. A
FLOOD RISK IS NOT DESIGNATED TODAY DUE TO IMPROVING CONDITIONS ANTICIPATED
DURING WEEK-2.
FORECASTER: RICH TINKER
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