695
FXUS02 KWBC 110631
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 AM EDT WED JUN 11 2025
VALID 12Z SAT JUN 14 2025 - 12Z WED JUN 18 2025
...HEAVY RAIN AND FLASH FLOOD THREAT FROM THE SOUTH-CENTRAL U.S.
THROUGH THE OHIO VALLEY/NORTHEAST INTO THE WEEKEND...
..GENERAL OVERVIEW
A SLOW MOVING SHORTWAVE TROUGH WILL BE LIFTING OUT OF THE SOUTH-
CENTRAL U.S. BY NEXT WEEKEND, BUT WILL BE SLOW TO MOVE OUT OF THE
OHIO VALLEY/MID-ATLANTIC REGION WITH PERIODIC RELOADING FROM
NORTHERN STREAM ENERGY. THIS WILL KEEP THE WEATHER UNSETTLED
THROUGH MUCH OF THE PERIOD WITH WIDESPREAD SHOWERS AND
THUNDERSTORMS, WITH MARGINAL THREATS FOR HEAVY TO EXCESSIVE
RAINFALL. SHORTWAVE ENERGY ORIGINATING FROM TROUGHING OVER THE WEST
COAST WILL SLIDE ACROSS THE NORTHERN TIER WITH ACCOMPANYING
SHOWERS AND STORMS. TROUGHING, IN SOME FORM, SHOULD MAINTAIN ACROSS
THE WESTERN U.S. INTO NEXT WEEK. HEAT WILL GENERALLY FOCUS OVER
THE SOUTHWEST THIS WEEKEND AND NEXT WEEK UNDERNEATH UPPER RIDGING.
..GUIDANCE/PREDICTABILITY ASSESSMENT
WHILE THERE IS SOME GENERAL AGREEMENT ON THE OVERALL PATTERN
EVOLUTION DESCRIBED ABOVE, THE GUIDANCE CONTINUES TO STRUGGLE ON
THE DETAILS OF THIS PATTERN WHICH FEATURES LESS PREDICTABLE SMALLER
SCALE FEATURES. THE BIGGEST AREA OF UNCERTAINTY IS OUT WEST, AS
MULTIPLE PERTURBATIONS EJECT INTO THE NORTHWEST AND NORTHERN TIER
OUT OF DEEPER TROUGHING OVER OR JUST OFF THE WEST COAST. MODELS
STRUGGLE WITH THE PARENT UPPER LOW, INITIALLY OVER THE GULF OF
ALASKA AND WHETHER IT DROPS SOUTHWARD (ECMWF AND UKMET) OR HANGS
NORTH JUST SOUTH OF THE GULF. THIS LEADS TO SOME VERY NOTICEABLE
LATE PERIOD DIFFERENCES ACROSS THE WEST. THE GFS IN PARTICULAR WAS
AN OUTLIER IN SHOWING A MUCH STRONGER RIDGE AXIS OVER THE
SOUTHWEST/WEST LATER IN THE PERIOD, WHILE THERE WAS BETTER
CONSENSUS FOR LOWER HEIGHTS. THE WPC FORECAST FOR TONIGHT WAS ABLE
TO LEAN HEAVIER ON THE DETERMINISTIC GUIDANCE THE FIRST FEW DAYS OF
THE PERIOD (THIS WEEKEND), BUT QUICKLY TRANSITIONED TO MAJORITY
ENSEMBLE MEANS BY NEXT WEEK. MAINTAINED SOME MINOR AMOUNTS OF THE
ECMWF JUST FOR SOME ADDED SYSTEM DEFINITION.
..WEATHER/HAZARDS HIGHLIGHTS
AN UNSETTLED WEATHER PATTERN IS EXPECTED TO BE IN PLACE ACROSS A
LARGE PORTION OF THE EASTERN THIRD OF THE COUNTRY THROUGH MUCH OF
THIS PERIOD. DAILY SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BE
WIDESPREAD FROM THE GULF COAST TO THE OHIO VALLEY/MID-ATLANTIC AND
THE NORTHEAST ASSOCIATED WITH WEAK, BUT PERSISTENT, UPPER LEVEL
ENERGY OVER THE REGION. THERE REMAINS A LOT OF UNCERTAINTY IN THE
DETAILS, BUT THERE IS SOME GENERAL AGREEMENT THAT HEAVIER RAINS MAY
FOCUS ALONG A SLOW MOVING FRONTAL BOUNDARY DRAPED FROM THE MID-
ATLANTIC WESTWARD AND A WEAK AREA OF LOW PRESSURE ALONG THE FRONT.
WITHIN A MOIST AND UNSTABLE ENVIRONMENT, MAINTAINED A VERY BROAD
MARGINAL RISK AREA ON BOTH THE DAYS 4 AND 5 EXCESSIVE RAINFALL
OUTLOOKS STRETCHED FROM THE GULF COAST NORTHEASTWARD. IT IS
POSSIBLE EMBEDDED SLIGHT RISKS WILL BE NEEDED, BUT STILL TOO EARLY
AND TOO MUCH UNCERTAINTY, TO PICK OUT WHERE YET. REFINEMENTS TO
THESE EROS WILL BE NEEDED WITH TIME. FARTHER NORTH, SHORTWAVE
ENERGY THROUGH THE NORTHERN TIER WILL SUPPORT SHOWERS AND STORMS,
WITH A MARGINAL RISK HIGHLIGHTED ON THE DAY 5 ERO FOR PARTS OF THE
MIDWEST. MODERATE TO HEAVIER RAIN MAY TRY TO MATERIALIZE ACROSS
PARTS OF THE NORTH-CENTRAL U.S. NEXT WEEK AS A STRONGER SHORTWAVE
MOVES INTO THE PLAINS.
TEMPERATURES SHOULD REMAIN SLIGHTLY ABOVE NORMAL FOR MUCH OF THE
INTERMOUNTAIN WEST THIS WEEKEND UNDER THE INFLUENCE OF AN UPPER
RIDGE. TEMPERATURES SHOULD BE CLOSER TO NORMAL ALONG THE COAST.
SHORTWAVE ENERGY MOVING INTO THE REGION NEXT WEEK SHOULD HELP
MODERATE TEMPERATURES ACROSS THE INTERIOR WEST SOMEWHAT. TO THE
SOUTH, HEAT WILL BUILD ACROSS THE DESERT SOUTHWEST WITH HIGHS
MAKING A RUN AT 110 DEGREES FOR THE LOWER ELEVATIONS OF SOUTHERN
ARIZONA AND SOUTHEAST CALIFORNIA, WITH HEAT RISK LIKELY REACHING
THE MAJOR CATEGORY BY SUNDAY AND MONDAY, WITH ADDITIONAL THREAT
EXTENDING WELL INTO NEXT WEEK. MEANWHILE, SLIGHTLY BELOW AVERAGE
TEMPERATURES ARE LIKELY FROM THE UPPER MIDWEST TO THE GREAT LAKES
AND NORTHERN NEW ENGLAND GOING INTO THE WEEKEND AS THIS REGION WILL
BE NORTH OF THE MAIN FRONTAL BOUNDARY.
SANTORELLI
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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