257
FXUS02 KWBC 231959
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
359 PM EDT TUE JUN 23 2026
VALID 12Z FRI JUN 26 2026 - 12Z TUE JUN 30 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
A ZONAL UPPER-LEVEL FLOW PATTERN AT THE START OF THE MEDIUM-RANGE
PERIOD IS FORECAST TO BECOME MORE AMPLIFIED BY EARLY NEXT WEEK WITH
A PRONOUNCED UPPER LOW/TROUGH TRAVERSING THE NORTHWESTERN QUADRANT
OF THE COUNTRY. THE DEEP TROUGHING IN THE WEST WILL BE IN CONTRAST
WITH AN UPPER RIDGE BUILDING OVER THE EAST-CENTRAL U.S. BY EARLY
NEXT WEEK. A RETURN TO HEAT AND HUMIDITY IS EXPECTED FOR MUCH OF
THE CENTRAL AND SOUTHERN U.S. WHICH WILL BE IN STARK CONTRAST WITH
LATE-SEASON MOUNTAIN SNOWS IN THE NORTHERN ROCKIES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MUCH OF THE VARIABILITY SEEN IN THE MORNING SUITE OF MODEL
GUIDANCE WAS FOUND FROM THE MIDWEST AND OHIO VALLEY TO THE GREAT
LAKES. THE QPF AXIS THIS FRIDAY INTO THE WEEKEND HAS BEEN EXTENDING
FASTER AND FARTHER EASTWARD ACROSS THE MIDWEST TO THE OHIO VALLEY
GIVEN A FASTER EJECTION OF A COUPLE OF SHORTWAVES ALONG THE
STATIONARY/WARM FRONT. FROM THIS WEEKEND INTO EARLY NEXT WEEK, THE
MOST RECENT MODEL TREND HAS BEEN TO LIFT THE ELONGATED LOW-
PRESSURE SYSTEM FASTER NORTHEAST TOWARD SOUTHERN CANADA IN RESPONSE
TO A STRONGER UPPER RIDGE EXTENDING NORTH ACROSS THE MIDWEST. THIS
STRONGER RIDGE IMPLIES AN INCREASING CHANCE FOR HEAT TO BUILD INTO
THE UPPER MIDWEST EARLY NEXT WEEK. THE FASTER NORTHEASTWARD MOTION
OF THE LOW IN THE NORTH-CENTRAL U.S. WOULD ALSO IMPLY AN EARLIER
DEPARTURE OF THE RAIN/STORMS FROM THE NORTHERN PLAINS INTO SOUTHERN
CANADA EARLY NEXT WEEK.
THE WPC PROGNOSTIC CHARTS WERE BASED ON THE CONSENSUS OF THE 06Z
GFS/GEFS, 00Z EC/EC MEAN, AND THE 00Z CMC/CMC MEAN. 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
BLOBS AS WELL AS WITH A SMOOTHER DROP-OFF GRADIENT. IN ADDITION,
TEMPERATURES WERE LOWERED FOR COASTAL AREAS OF THE MID-ATLANTIC,
NORTHEAST, AND THE GREAT LAKES.
..WEATHER/HAZARDS HIGHLIGHTS
MULTIPLE MESOSCALE CONVECTIVE SYSTEMS ARE LIKELY TO AFFECT MUCH OF
THE MIDWEST AND EXTENDING EASTWARD TO INCLUDE THE OHIO VALLEY
THROUGH THE END OF THE WEEK AND INTO SATURDAY, WITH SOME AREAS
GETTING AN ADDITIONAL 1-3 INCHES OF RAIN OVER ALREADY SATURATED
GROUNDS FROM RECENT HEAVY RAINFALL. A LINGERING FRONTAL BOUNDARY
WITH SHORTWAVE ENERGY ALOFT AND STRONG MOISTURE CONVERGENCE WILL
PROVIDE ENOUGH INSTABILITY AND LIFT TO SUSTAIN THESE THUNDERSTORM
COMPLEXES, AND SOME OF THESE STORMS POSSIBLY PRODUCING FLASH
FLOODING, INCLUDING THE POTENTIAL FOR SOME STRONG TO SEVERE
THUNDERSTORMS. A MARGINAL RISK OF EXCESSIVE RAINFALL IS HIGHLIGHTED
ON THE WPC EXCESSIVE RAINFALL OUTLOOK ACROSS THE EAST-CENTRAL U.S.
FRIDAY TO THE WEEKEND.
ELSEWHERE ACROSS THE NATION, RAINFALL IS FORECAST TO INCREASE FOR
WASHINGTON AND OREGON TO CLOSE OUT THE WORK WEEK WITH THE STORM
SYSTEM MOVING THROUGH THE REGION, WITH A LARGER AREA OF HEAVIER
RAINFALL DEVELOPS ACROSS MONTANA AND THEN THE DAKOTAS AS THE MAIN
SURFACE LOW EJECTS EASTWARD OVER THE NORTHERN PLAINS BY THE
WEEKEND. A MARGINAL RISK OF EXCESSIVE RAINFALL IS HIGHLIGHTED
ACROSS THE FAR NORTHERN PLAINS FOR DAY 5 ON THE WPC EXCESSIVE
RAINFALL OUTLOOK. IN ADDITION, LATE-SEASON HIGH ELEVATION SNOW IS
LIKELY FOR THE HIGHEST RANGES OF THE NORTHERN ROCKIES AS THE COLDER
UPPER LOW MOVES IN. SCATTERED SHOWERS AND THUNDERSTORMS ARE ALSO
EXPECTED FOR THE EAST COAST THROUGH SATURDAY WITH INCREASING LOW
LEVEL MOISTURE IN PLACE.
THE WIDESPREAD ABOVE AVERAGE HEAT LEVELS ACROSS THE WESTERN THIRD
OF THE NATION ARE EXPECTED TO ABATE CONSIDERABLY GOING INTO THE
WEEKEND. A STRONG COLD FRONT BRINGS RELIEF FROM THE HEAT STARTING
FRIDAY FOLLOWED BY MORE APPRECIABLE COOLING GOING INTO THE WEEKEND
AS HIGHS RETURN TO BELOW AVERAGE FOR LATE JUNE STANDARDS, WHEREAS
OVERNIGHT LOWS SHOULD BE LESS ANOMALOUS. THE OPPOSITE HOLDS TRUE
FOR THE SOUTHERN HIGH PLAINS WHERE TEMPERATURES ARE LIKELY TO
INCREASE BY THE WEEKEND WITH HIGHS WELL INTO THE 100S FOR WESTERN
TEXAS, AND BUILDING HEAT AND HUMIDITY FOR MUCH OF THE CENTRAL AND
EASTERN U.S. GOING INTO SUNDAY AND MONDAY AS THE UPPER RIDGE
DOMINATES THE WEATHER PATTERN. WIDESPREAD MAJOR HEAT RISK IS
CURRENTLY DEPICTED ACROSS MUCH OF THE CENTRAL TO SOUTHEASTERN U.S.
WHERE HEAT ADVISORIES ARE LIKELY FOR MANY AREAS FOR EARLY NEXT
WEEK.
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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