940
FXUS02 KWBC 241959
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
359 PM EDT WED JUN 24 2026
VALID 12Z SAT JUN 27 2026 - 12Z WED JUL 01 2026
***ADDITIONAL HEAVY RAIN FOR THE MIDWEST AND OHIO VALLEY***
***HEAT AND HUMIDITY INCREASES ACROSS THE CENTRAL AND SOUTHERN
U.S. STARTING THIS WEEKEND***
..PATTERN OVERVIEW
AN ANOMALOUS UPPER LOW DIGGING INTO THE NORTHWESTERN STATES WILL
PUT AN END TO THE HEAT WAVE ACROSS THE SOUTHWEST AND EVEN LEAD TO
SOME HIGHER ELEVATION SNOW FOR THE NORTHERN ROCKIES. THIS TROUGH
WILL SPUR SURFACE CYCLOGENESIS ACROSS THE PLAINS WITH AN OCCLUDED
LOW LIFTING NORTH ACROSS SOUTH-CENTRAL CANADA. IN CONTRAST, A
BUILDING DOWNSTREAM UPPER RIDGE ACROSS THE EAST-CENTRAL U.S. WILL
RESULT IN INCREASING HEAT AND HUMIDITY GOING INTO NEXT WEEK.
NUMEROUS SHOWERS AND STORMS ARE LIKELY FROM THE OHIO VALLEY TO THE
NORTHEAST ON SATURDAY TO THE SOUTH OF A SLOW-MOVING FRONTAL
BOUNDARY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
ASSESSMENT OF THE LATEST MODEL GUIDANCE SUITE CONTINUES TO
HIGHLIGHT A FASTER EASTWARD EJECTION OF A SHORTWAVE FROM THE OHIO
VALLEY TOWARD THE MID-ATLANTIC ALONG THE STATIONARY FRONT THIS
WEEKEND. MEANWHILE, MODEL CONSENSUS HAS CONTINUED TO TREND TOWARD A
HIGHER AMPLITUDE RIDGE TO EXTEND NORTHWARD ACROSS THE MIDWEST FROM
AN EXPANDING CLOSED UPPER HIGH CENTERED OVER THE EAST-CENTRAL U.S.
WHILE THE UPPER LOW OVER THE NORTHWEST U.S. LIFTS INTO SOUTHERN
CANADA AND OPENS INTO A POSITIVELY-TILTED TROUGH. THE STRONGER
RIDGE CONTINUES TO INCREASE THE CHANCE FOR HEAT TO BUILD ACROSS THE
UPPER MIDWEST EARLY NEXT WEEK. IN ADDITION, LATEST 12Z ECMWF
CONTINUES THE TREND TO INCREASE THE STRENGTH OF THE UPPER HIGH OVER
THE SOUTHEAST U.S. WHICH WOULD SUPPORT THE CHANCE FOR THE HEAT TO
INCREASE ACROSS THE EAST-CENTRAL U.S. TO THE SOUTHEAST TOWARD THE
MIDDLE OF NEXT WEEK. IN CONTRAST, MODELS HAVE TRENDED TOWARD LOWER
HEIGHTS TO DIP FURTHER SOUTH INTO THE GREAT BASIN WITH COOLER
TEMPERATURES THAN IN PREVIOUS FORECASTS.
THE WPC FRONTS/PRESSURES WERE BASED ON A GENERAL DETERMINISTIC
MODEL BLEND FOR THE WEEKEND, FOLLOWED BY A HIGHER PERCENTAGE OF
THE ENSEMBLE MEANS TOWARDS THE MIDDLE OF NEXT WEEK. THE NBM WAS A
REASONABLE STARTING POINT FOR MOST AREAS OF THE COUNTRY, ALTHOUGH A
SMOOTHER QPF FIELD WAS USED TO REPLACE SOME OF THE HIGH QPF MAXIMA
AND A REDUCTION OF 0.02 INCH AREAS WHERE IT WAS WIDESPREAD. IN
ADDITION, TEMPERATURES WERE LOWERED FOR COASTAL AREAS OF THE MID-
ATLANTIC, NORTHEAST, AND THE GREAT LAKES.
..WEATHER/HAZARDS HIGHLIGHTS
A STORMY START TO THE WEEKEND IS FORECAST ACROSS THE OHIO VALLEY
AND INTO THE CENTRAL APPALACHIANS AS A WAVE OF LOW PRESSURE AND A
SHORTWAVE ALOFT FUEL THE DEVELOPMENT OF WIDESPREAD SHOWERS AND
STORMS, WITH 1-2 INCH RAINFALL TOTALS LIKELY WHERE STORMS ARE MOST
PERSISTENT. ANOTHER REGION OF PERTURBED WEATHER WILL ALSO BE LIKELY
ACROSS THE DAKOTAS WITH ENHANCED RAINFALL AND STRONG/SEVERE
THUNDERSTORMS DEVELOPING NEAR THE MAIN SURFACE LOW. BOTH OF THESE
AREAS PROBABLY HAVE AN ABATEMENT IN RAINFALL COVERAGE AND INTENSITY
BY SUNDAY. LOOKING AHEAD TO MONDAY/TUESDAY, A CORRIDOR OF SHOWERS
AND STORMS, SOME OF WHICH COULD BE HEAVY, ARE FORECAST TO DEVELOP
FROM NEBRASKA TO THE UPPER PENINSULA OF MICHIGAN AHEAD OF THE COLD
FRONT CROSSING THE UPPER MIDWEST.
ELSEWHERE ACROSS THE COUNTRY, DECREASING SNOW LEVELS ACROSS THE
NORTHERN ROCKIES WILL LEAD TO A VERY LATE SEASON SNOWFALL ACROSS
THE HIGHER TERRAIN OF WESTERN MONTANA, CENTRAL IDAHO, AND
NORTHWESTERN WYOMING, ESPECIALLY SATURDAY NIGHT INTO EARLY SUNDAY,
AND COLD RAIN FOR THE VALLEYS. SOME THUNDERSTORMS MAY DEVELOP
ALONG THE DRYLINE ACROSS WESTERN TEXAS FOR THE BEGINNING OF THE
WEEK, BUT CURRENTLY NOT EXPECTED TO BE WIDESPREAD. SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED FROM THE CENTRAL GULF COAST
TO THE FLORIDA PENINSULA FOR THE FIRST HALF OF NEXT WEEK WITH
MOISTURE INCREASING SOUTH OF THE UPPER RIDGE.
A TEMPERATURE DICHOTOMY WILL EXIST ACROSS THE COUNTRY STARTING THIS
WEEKEND AS THE DEEP UPPER TROUGH HERALDS THE ARRIVAL OF MUCH COOLER
CONDITIONS STARTING ACROSS THE PACIFIC NORTHWEST, AND THEN THE
ROCKIES BY SUNDAY WITH HIGHS RUNNING ON THE ORDER OF 15-25 DEGREES
BELOW LATE JUNE AVERAGES. THIS WILL LIKELY BE COLD ENOUGH TO
ESTABLISH SOME NEW DAILY RECORD LOW TEMPERATURES. THE OPPOSITE WILL
HOLD TRUE FROM THE PLAINS TO THE OHIO VALLEY WITH WIDESPREAD ABOVE
AVERAGE TEMPERATURES EXPECTED WITH THE STRONG UPPER RIDGE
DEVELOPING. HIGHS IN THE 90S ARE EXPECTED AS FAR NORTH AS THE GREAT
LAKES AND MINNESOTA, AND 100S FOR MUCH OF TEXAS. HEAT INDICES
APPROACHING 110 DEGREES ARE POSSIBLE FROM THE MID-SOUTH TO THE
CENTRAL GULF COAST WHERE THE COMBINATION OF HEAT AND HIGH DEWPOINTS
WILL BE GREATEST. OVERNIGHT LOWS WILL ALSO BE QUITE WARM, WITH
SOME RECORD HIGH MINIMUMS POSSIBLE.
KONG/HAMRICK
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES
ARE AT:
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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