843
FXUS02 KWBC 080742
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
342 AM EDT MON JUN 8 2026
VALID 12Z THU JUN 11 2026 - 12Z MON JUN 15 2026
...SIGNIFICANT HEAT WAVE IS EXPECTED FOR THE EAST LATE WEEK WITH
HOT CONDITIONS BACK INTO THE SOUTH-CENTRAL U.S. AS WELL...
...SEVERE WEATHER AND HEAVY RAIN THREATS ACROSS THE UPPER GREAT
LAKES/OHIO VALLEY/MID-MISSISSIPPI VALLEY...
..OVERVIEW
A BROADENING UPPER TROUGH ACROSS THE NORTHERN TIER OF THE U.S.
WILL PUSH A FRONT TO ITS EAST AND SOUTH, PROVIDING A FOCUS FOR
SEVERE THUNDERSTORMS AND HEAVY RAIN ACROSS THE UPPER GREAT
LAKES/OHIO VALLEY AS THE FORECAST PERIOD BEGINS THURSDAY. THE FRONT
IS FORECAST TO STALL ACROSS THE CENTRAL U.S. BY LATE WEEK AND
TRIGGER ADDITIONAL ROUNDS OF THUNDERSTORMS IN THE SOUTHERN/CENTRAL
PLAINS AND LOWER/MIDDLE MISSISSIPPI VALLEY THROUGH THE WEEKEND AND
EARLY NEXT WEEK. MEANWHILE, A MEAN UPPER RIDGE AHEAD OF THE TROUGH
WILL SUPPORT THE FIRST SIGNIFICANT HEAT WAVE OF THE SEASON SHIFTING
INTO THE EASTERN U.S. LATE WEEK AND OVER THE WEEKEND. THEN INTO
EARLY NEXT WEEK, WARM TEMPERATURES MAY SURGE INTO THE PACIFIC
NORTHWEST WITH UPPER RIDGING ON THE BACKSIDE OF THE TROUGH, THOUGH
THIS REMAINS UNCERTAIN.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATE THIS WEEK, THE UPPER-LEVEL PATTERN PRIMARILY CONSISTS OF A
SHALLOW UPPER TROUGH ATOP THE NORTH-CENTRAL U.S., MEAN RIDGING OVER
THE EAST, AND SUBTROPICAL RIDGING IN THE SOUTHERN U.S. THAT WILL
BE PERSISTENT. THE TROUGH WILL GRADUALLY PUSH A FRONT AHEAD OF IT
AS IT MOVES EAST THROUGH THE GREAT LAKES/NORTHEAST INTO THE
WEEKEND, WITH SOME TIMING DIFFERENCES REMAINING IN THE MODEL
GUIDANCE. 00Z MODELS ARE GENERALLY A BIT FARTHER SOUTHEAST WITH THE
BASE OF THE TROUGH THROUGH THE GREAT LAKES REGION BY EARLY
SATURDAY COMPARED TO THE PREVIOUS CYCLE. THE DEPTH OF THE TROUGH
WILL PLAY A ROLE IN WHERE THE BACK END OF THE FRONT SETS UP
GENERALLY WEST-EAST ACROSS THE CENTRAL U.S. TO FOCUS THUNDERSTORM
CHANCES, AND THESE DETAILS WILL TAKE ADDITIONAL TIME TO RESOLVE.
ANOTHER UNCERTAIN ASPECT OF THE FORECAST IS THE PATTERN ACROSS THE
NORTHWEST OVER THE WEEKEND INTO EARLY NEXT WEEK, NAMELY THE BATTLE
BETWEEN AN EASTERN PACIFIC UPPER RIDGE AND ENERGY DROPPING SOUTH
ON THE WESTERN SIDE OF THE BROAD TROUGH FORMING A POSSIBLE
SHORTWAVE THAT COULD RETROGRADE. DYNAMICAL AND AI GUIDANCE HAVE
BEEN WAFFLING WITH THE POSITIONING OF THIS ENERGY. THE DYNAMICAL
EC/GFS RUNS FROM THE 12/18Z CYCLE INDICATED CONSIDERABLE SHORTWAVE
ENERGY HANGING BACK INTO THE NORTHWEST, KEEPING THE RIDGE MAINLY
OFFSHORE IN THE PACIFIC. MEANWHILE THE AI MODELS FROM 12/18Z AND
THE 00Z CYCLES ARE SHOWING THE ENERGY FARTHER EAST NEARER THE
TROUGH, WHICH ALLOWS MORE RIDGING ATOP THE PACIFIC NORTHWEST. THE
MOST RECENT 00Z GFS/ECMWF TRENDED TOWARD THE AI TYPE SOLUTION.
HOWEVER, THE OPPOSITE HAPPENED LAST NIGHT, WHERE THE AI GUIDANCE
WAS SHOWING A STRONGER NORTHWEST SHORTWAVE AND THE 00Z (JUNE 7TH)
GUIDANCE TRENDED TOWARD THAT. SO NOT CONFIDENT ENOUGH YET TO SAY
THIS IS A REAL MODEL TREND, AND WILL CONTINUE TO MONITOR. THIS HAS
SENSIBLE WEATHER IMPACTS LIKE TEMPERATURES IN THE NORTHWEST. IT
ALSO PLAYS A ROLE IN THE POTENTIAL FOR THE TROUGH TO DIG IN THE
ROCKIES/HIGH PLAINS AND VICINITY EARLY NEXT WEEK (GFS SEEMS MOST
AGGRESSIVE WITH THAT POTENTIAL).
THE WPC FORECAST FOR FRONTS/PRESSURES WAS BASED ON A MULTI-MODEL
BLEND OF THE 00Z GUIDANCE EARLY IN THE FORECAST, WITH INCREASING
PROPORTIONS OF THE GEFS/EC ENSEMBLE MEANS AS THE PERIOD PROGRESSED
TO ABOUT HALF BY DAY 7 AMID INCREASING SPREAD.
..WEATHER/HAZARDS HIGHLIGHTS
A COLD FRONT IS FORECAST TO PUSH ACROSS THE MIDWEST ON THURSDAY
AND PROVIDE A FOCUS FOR THUNDERSTORMS IN A MOIST AND UNSTABLE
ENVIRONMENT. FLASH FLOODING IS A POSSIBILITY WITH POTENTIALLY
REPEATING ROUNDS OF CONVECTION, AND A SLIGHT RISK IS IN PLACE
ACROSS PORTIONS OF THE MID-MISSISSIPPI VALLEY AND WESTERN OHIO
VALLEY IN THE DAY 4/THURSDAY ERO. THE STORM PREDICTION CENTER IS
CALLING FOR A RISK OF SEVERE WEATHER IN A SIMILAR AREA AS WELL. THE
FRONT WILL PUSH EASTWARD INTO FRIDAY AND COULD PRODUCE LOCALLY
HEAVY RAIN IN PARTS OF THE APPALACHIANS FRIDAY, AND A MARGINAL RISK
IS INDICATED THERE FOR THE DAY 5/FRIDAY ERO. MEANWHILE, THE FRONT
WILL START TO LAY FLAT ACROSS THE CENTRAL U.S. AND MEANDER NEAR
SOUTH-CENTRAL PARTS OF THE PLAINS AND MISSISSIPPI VALLEY TO THE
TENNESSEE/OHIO VALLEYS, ALLOWING FOR THE MARGINAL TO STRETCH ACROSS
THOSE REGIONS. THE GENERALLY WEST TO EAST ORIENTED FRONT IS
FORECAST TO MEANDER IN THE CENTRAL U.S. FOR MULTIPLE DAYS. THUS
THUNDERSTORMS WILL BE COMMON IN THAT REGION INTO THE WEEKEND, WITH
HEAVY RAIN POTENTIAL AND ADDITIONAL FLOOD RISKS ESPECIALLY IF
ROUNDS OF RAIN REPEAT OVER SIMILAR AREAS. SCATTERED THUNDERSTORMS
THAT TEND TO BE DIURNALLY DRIVEN ARE LIKELY IN THE SOUTHEAST
(INCLUDING FLORIDA) AND POTENTIALLY EXPANDING INTO THE MID-ATLANTIC
FOR MULTIPLE DAYS. ELSEWHERE, THE NORTHERN ROCKIES AND HIGH PLAINS
MAY SEE SOME PRECIPITATION, DEPENDENT ON THE EVOLUTION OF
SHORTWAVE ENERGY.
THE MEAN UPPER-LEVEL RIDGE OVER THE EASTERN U.S. IS EXPECTED TO
BRING THE FIRST SIGNIFICANT HEAT OF THE SUMMER INTO LATE WEEK, AS
TEMPERATURES REACH 10-15 DEGREES ABOVE AVERAGE. THE HEAT LOOKS TO
REACH ITS PEAK ACROSS THE MID-ATLANTIC AND NORTHEAST ON FRIDAY, AND
SEVERAL RECORD HIGHS AND RECORD WARM MINIMUM TEMPERATURES COULD BE
SET, BEFORE GRADUALLY MODERATING BY THE WEEKEND. SEE WPC'S KEY
MESSAGES FOR MORE. SUBTROPICAL RIDGING ACROSS THE SOUTHERN TIER
WILL YIELD HOT CONDITIONS THERE AS WELL, GENERALLY A FEW DEGREES
ABOVE ALREADY WARM AVERAGES. THE DESERT SOUTHWEST CAN EXPECT
TEMPERATURES WELL INTO THE 100S, WHILE HEAT INDICES SHOULD BE OVER
100 IN THE SOUTHERN PLAINS TO LOWER MISSISSIPPI VALLEY. INTO EARLY
NEXT WEEK, UPPER RIDGING POSSIBLY REACHING THE WEST COAST COULD
BRING WELL ABOVE AVERAGE TEMPERATURES PARTICULARLY TO THE PACIFIC
NORTHWEST. THIS POTENTIAL IS STILL UNCERTAIN DUE TO MODEL SPREAD,
HOWEVER.
TATE
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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