838
FXUS02 KWBC 201752
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
152 PM EDT SAT JUN 20 2026
VALID 12Z TUE JUN 23 2026 - 12Z SAT JUN 27 2026
...HEAVY RAINFALL EXPECTED FOR THE CENTRAL PLAINS AND VERY HOT
CONDITIONS FOR THE DESERT SOUTHWEST...
..OVERVIEW
A QUASI-ZONAL UPPER LEVEL FLOW PATTERN WILL BE IN PLACE ACROSS THE
COUNTRY FOR THE BEGINNING OF THE PERIOD TUESDAY. AN UPPER LEVEL
RIDGE WILL BUILD ACROSS THE DESERT SOUTHWEST INTO PORTIONS OF THE
INTERMOUNTAIN WEST, WITH INCREASING HEAT THROUGH THE END OF THE
WEEK. A LINGERING FRONTAL BOUNDARY DRAPED ACROSS THE MID-SOUTH TO
THE CENTRAL PLAINS, COUPLED WITH SOME SHORTWAVE ENERGY ALOFT, WILL
FUEL THE DEVELOPMENT OF MULTIPLE THUNDERSTORM COMPLEXES THAT WILL
BRING EPISODES OF HEAVY RAINFALL. BY NEXT SATURDAY, AN ORGANIZED
LOW PRESSURE SYSTEM AND COLD FRONT CROSS THE NORTHWESTERN QUADRANT
OF THE COUNTRY AND WILL HERALD THE ARRIVAL OF COOLER WEATHER.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE LARGE SCALE PATTERN
THROUGH THE PERIOD, WITH UNCERTAINTY IN SOME OF THE DETAILS IN THE
SECOND HALF OF THE PERIOD. THE GFS HAS TRENDED CLOSER TO THE ECMWF
AND CMC OVER THE PAST 24 HOURS, BUT CONTINUES TO BE A BIT OF AN
OUTLIER, SHOWING A STRONG SHORTWAVE TROUGH CUTTING THROUGH THE
RIDGE OVER THE WEST LATE THIS WEEK. THE ECMWF, CMC, AIGFS, AND EC-
AIFS ALL MAINTAIN THE STRENGTH OF THE RIDGE AND BRING A MUCH WEAKER
SHORTWAVE INTO THE CENTRAL U.S. THURSDAY INTO FRIDAY, WHICH SEEMS
MORE LIKELY AT THIS TIME. HOWEVER THIS FEATURE EVOLVES, IT COULD
HAVE SIGNIFICANT IMPLICATIONS FOR PRECIPITATION AMOUNTS AND
LOCATION.
THE WPC FORECAST WAS INITIATED USING A NEAR EVEN BLEND OF THE
DETERMINISTIC GUIDANCE, BUT THE GFS WAS PHASED OUT BY MID-NEXT WEEK
AND THE GEFS AND ECENS WERE ADDED IN INCREASING AMOUNTS TO SMOOTH
OUT MODEL DIFFERENCES. IN TERMS OF THE NBM, IT IS LIKELY UNDERDONE
WITH THE COVERAGE OF AFTERNOON/EVENING SHOWERS AND STORMS ACROSS
THE FOUR CORNERS REGIONS MID-WEEK, SO QPF VALUES WERE RAISED A
LITTLE TO BETTER REFLECT THE DETERMINISTIC GUIDANCE.
..WEATHER/HAZARDS HIGHLIGHTS
THE WEATHER PATTERN WILL REMAIN QUITE UNSETTLED FROM THE CENTRAL
PLAINS TO THE ARKLATEX REGION THROUGH WEDNESDAY NIGHT WITH MULTIPLE
ROUNDS OF THUNDERSTORMS WITH HEAVY RAINFALL EXPECTED. THIS IS IN
ASSOCIATION WITH A FRONTAL BOUNDARY THAT WILL BE IN PLACE ACROSS
THIS REGION, WITH ANOMALOUS MOISTURE SURGING NORTH AND FUELING THE
CONVECTION THAT DEVELOPS. GOING INTO THE END OF THE WEEK, THE
HEAVIEST RAINFALL IS EXPECTED FROM EASTERN KANSAS TO ILLINOIS WHERE
ADDITIONAL THUNDERSTORM COMPLEXES ARE EXPECTED TO DEVELOP AND LEAD
TO PERIODS OF HEAVY RAINFALL.
TEMPERATURES ARE EXPECTED TO BE VERY PLEASANT BY LATE JUNE
STANDARDS ACROSS A LARGE EXPANSE OF THE NORTH-CENTRAL STATES
THROUGH MUCH OF NEXT WEEK, WITH HIGHS GENERALLY IN THE 70S AND
COMFORTABLE HUMIDITY LEVELS. MOST OF THE MID-ATLANTIC AND
NORTHEAST SHOULD BE CLOSE TO SEASONAL AVERAGES WITH HIGHS MAINLY IN
THE UPPER 70S TO MIDDLE 80S. WITH THE UPPER RIDGE OVER THE WEST
THROUGH FRIDAY, HEAT IS EXPECTED TO BUILD FROM THE DESERT SOUTHWEST
TO THE PACIFIC NORTHWEST, WITH HIGHS RUNNING 5 TO 10 DEGREES ABOVE
NORMAL IN MANY CASES. A PATTERN CHANGE IS EXPECTED TO ARRIVE NEXT
SATURDAY AS A COLD FRONT DROPS SOUTH ACROSS THE PACIFIC NORTHWEST
AND BRINGS AN END TO THE HEAT WAVE THERE. HOT AND HUMID CONDITIONS
WILL CONTINUE UNABATED ACROSS THE DEEP SOUTH AND GULF COAST REGION.
DOLAN/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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