585
FXUS02 KWBC 250630
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 AM EDT THU JUN 25 2026
VALID 12Z SUN JUN 28 2026 - 12Z THU JUL 2 2026
***HEAT AND HUMIDITY INCREASES ACROSS THE CENTRAL AND EASTERN U.S.
FOR MUCH OF NEXT WEEK***
..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 MONTANA AND IDAHO 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 MUCH
OF NEXT WEEK WITH WIDESPREAD 90S ACROSS THE EASTERN HALF OF THE
COUNTRY. SHOWERS AND THUNDERSTORMS WILL BE MOST LIKELY ACROSS THE
GULF COAST REGION, THE SOUTHERN ROCKIES, AND THE UPPER MIDWEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE IS IN RELATIVELY GOOD AGREEMENT ON
MOST ASPECTS OF THE FORECAST. THE 12Z CMC WAS AN OUTLIER SOLUTION
WITH RESPECT TO A STRONGER TROUGH CROSSING THE UPPER MIDWEST AND
GREAT LAKES FOR EARLY NEXT WEEK, WHEREAS THE OTHER GUIDANCE AND
ENSEMBLES SUPPORTED A STRONGER RIDGE AXIS. THE 00Z CMC RUN IS
CLOSER TO THE CONSENSUS, BUT STILL MORE SUPPRESSED WITH THE UPPER
RIDGE OVER THE EAST-CENTRAL U.S. COMPARED TO THE OTHER GUIDANCE.
THE GFS BECOMES STRONGER WITH A SECOND TROUGH BUILDING IN ACROSS
THE PACIFIC NORTHWEST LATE IN THE PERIOD.
THE WPC FRONTS/PRESSURES WERE BASED ON A GENERAL DETERMINISTIC
MODEL BLEND FOR SUNDAY INTO MONDAY, WITH LESS OF THE CMC USED GIVEN
THE DIFFERENCES NOTED ACROSS THE GREAT LAKES REGION AND GREATER
RUN-TO-RUN VARIATIONS. THIS WAS FOLLOWED BY A HIGHER PERCENTAGE OF
THE ENSEMBLE MEANS TOWARDS WEDNESDAY AND THURSDAY. THE NBM WAS A
REASONABLE STARTING POINT FOR MOST AREAS OF THE COUNTRY, ALTHOUGH
QPF WAS INCREASED SOME FOR PORTIONS OF WESTERN TEXAS AND INTO
CENTRAL AND EASTERN NEW MEXICO WITH INCREASING MONSOONAL MOISTURE
ON THE BACK SIDE OF THE UPPER RIDGE. IN ADDITION, TEMPERATURES WERE
LOWERED FOR COASTAL AREAS OF THE MID-ATLANTIC, NORTHEAST, AND THE
GREAT LAKES.
..WEATHER/HAZARDS HIGHLIGHTS
THERE SHOULD BE AN OVERALL DECREASE IN RAINFALL COVERAGE GOING INTO
SUNDAY ACROSS MOST OF THE COUNTRY COMPARED TO THE SHORT RANGE
FORECAST PERIOD. THERE WILL LIKELY BE SOME SHOWERS AND STORMS NEAR
THE COASTAL CAROLINAS AS A WEAK WAVE OF LOW PRESSURE DEVELOPS
OFFSHORE. RAIN AND MOUNTAIN SNOW OVER CENTRAL AND WESTERN MONTANA
SHOULD STILL BE ONGOING, WITH SEVERAL INCHES OF SNOW ACCUMULATION
POSSIBLE FOR THE HIGHEST MOUNTAIN RANGES. 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, SOME THUNDERSTORMS ARE LIKELY TO
DEVELOP IN THE VICINITY OF THE DRYLINE ACROSS WESTERN TEXAS AND
EASTERN NEW MEXICO FOR THE FIRST HALF OF THE WEEK, WITH A HIGHER
TREND COMPARED TO PREVIOUS FORECASTS. SCATTERED SHOWERS AND
THUNDERSTORMS ARE EXPECTED FROM THE CENTRAL GULF COAST TO THE
FLORIDA PENINSULA WITH MOISTURE INCREASING SOUTH OF THE UPPER
RIDGE, WITH MOST OF THESE HAPPENING DURING THE AFTERNOON AND
EVENING HOURS.
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 NORTHERN
ROCKIES, WITH HIGHS RUNNING ON THE ORDER OF 15-25 DEGREES BELOW
LATE JUNE AVERAGES. THIS WILL LIKELY BE COLD ENOUGH TO COME CLOSE
TO 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. SOME 100+ DEGREE
READINGS ARE ALSO POSSIBLE FOR PORTIONS OF THE SOUTHEAST BY
THURSDAY. 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.
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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