451
FXUS02 KWBC 090714
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 AM EDT TUE JUN 9 2026
VALID 12Z FRI JUN 12 2026 - 12Z TUE JUN 16 2026
...SIGNIFICANT HEAT WAVE CULMINATES FRIDAY IN THE EAST WITH HOT
CONDITIONS EXTENDING INTO THE SOUTH-CENTRAL U.S. THROUGH SUNDAY...
...HEAT BUILDING ACROSS THE WEST THIS WEEKEND INTO EARLY NEXT
WEEK...
...MULTI-DAY HEAVY RAINFALL THREAT IN SOUTHERN/CENTRAL PARTS OF THE
PLAINS AND MISSISSIPPI VALLEY...
..OVERVIEW
A BROAD UPPER TROUGH WITH EMBEDDED SHORTWAVES WILL BE PRESENT
ACROSS THE NORTHWESTERN TO NORTH-CENTRAL TIER OF THE U.S. AS THE
MEDIUM RANGE PERIOD BEGINS FRIDAY, GRADUALLY PUSHING EAST AND
RELOADING OVER THE WEEKEND INTO NEXT WEEK. AHEAD OF THE TROUGH,
HEAT IS FORECAST TO SURGE ACROSS THE EAST PARTICULARLY ON FRIDAY,
WHILE THE SOUTHERN TIER REMAINS HOT AND HUMID AS WELL. OVER THE
WEEKEND AND EARLY NEXT WEEK, UPPER RIDGING BUILDING IN THE WEST
BEHIND THE TROUGH WILL LEAD TO WARM TO HOT TEMPERATURES THERE.
PRECIPITATION-WISE, A FRONT IS FORECAST TO MEANDER ON THE
SOUTHERN/EASTERN SIDE OF THE TROUGH AND FOCUS MOISTURE FOR RAIN AND
THUNDERSTORMS. HEAVY RAINFALL IS POSSIBLE WITH MULTIPLE ROUNDS OF
STORMS EXPECTED TO SET UP IN THE SOUTHERN/CENTRAL PLAINS AND
LOWER/MID-MISSISSIPPI VALLEY OVER THE WEEKEND INTO EARLY NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE IS GENERALLY AGREEABLE WITH THE OVERALL PATTERN
EARLY IN THE PERIOD. MODELS INDICATE THE BASE OF THE EASTERN SIDE
OF THE TROUGH WILL BE OVER THE MIDWEST FRIDAY AND TRACK INTO THE
NORTHEAST OVER THE WEEKEND, PUSHING A FRONT EAST AND EASING THE
WARM TEMPERATURES THERE. MEANWHILE A SHORTWAVE WILL DIVE INTO THE
NORTHERN ROCKIES/HIGH PLAINS BY SATURDAY AND REINFORCE THE TROUGH
ON THE BACKSIDE. THIS SHORTWAVE HAS SHOWN SOME WAFFLING IN POSITION
IN THE MODELS. MOST GUIDANCE FROM THE 12/18Z CYCLE KEEPS THE
SHORTWAVE EAST AND ALLOWS FOR MORE RIDGING IN THE PACIFIC NORTHWEST
OVER THE WEEKEND. HOWEVER, 00Z MODELS HAVE SHOWN A TREND FARTHER
WEST, MOST DRAMATICALLY THE 00Z ECMWF HOVERING OVER THE NORTHWEST
STATES BY SUNDAY. THE RECENT AIFS/AIGFS SEEM TO BE A MIDDLE GROUND
WITH THE SHORTWAVE POSITION, WHILE THE GFS AND ESPECIALLY THE CMC
ARE ON THE EASTERN SIDE. THE PLACEMENT OF THIS SHORTWAVE VS. THE
EASTERN PACIFIC RIDGE FROM DAY TO DAY WILL AFFECT TEMPERATURES IN
THE NORTHWEST. THE SHORTWAVE WILL CONTINUE TO DIG SOUTHEASTWARD AND
GRADUALLY DEEPEN THE TROUGH INTO EARLY NEXT WEEK. THIS DIGGING
COULD OCCUR ANYWHERE FROM THE ROCKIES/HIGH PLAINS IN THE WESTERN
MODELS LIKE THE EC TO THE MIDWEST IN EASTERN MODELS LIKE THE CMC.
BUT IN GENERAL, A CENTRAL U.S. TROUGH SHOULD BE IN PLACE BY DAY
7/TUESDAY WHILE RIDGING IS PRESENT IN THE WEST, AND SUBTROPICAL
RIDGING STRETCHING AT LEAST INTO FLORIDA IF NOT FARTHER NORTH IN
THE EAST.
THE WPC FORECAST WAS BASED ON A MULTI-MODEL BLEND EARLY IN THE
FORECAST PERIOD, AND LEANED MORE HEAVILY ON THE AIFS AND ENSEMBLE
MEANS AS THE PERIOD PROGRESSED AMID INCREASING SPREAD IN THE
DETERMINISTIC GUIDANCE.
..WEATHER/HAZARDS HIGHLIGHTS
A FRONTAL BOUNDARY IS FORECAST TO STRETCH ACROSS THE INTERIOR
NORTHEAST SOUTHWESTWARD ACROSS THE OHIO VALLEY TO MID-SOUTH AND
BACK INTO THE SOUTH-CENTRAL PLAINS ON FRIDAY. THE FRONT WILL FOCUS
MOISTURE AND INSTABILITY FOR THUNDERSTORM CHANCES ALONG THE
BOUNDARY. SOME LOCALLY HEAVY RAIN COULD CAUSE ISOLATED FLASH
FLOODING, SO A MARGINAL RISK REMAINS IN PLACE FOR THE DAY 4/FRIDAY
ERO. BY SATURDAY, THE FRONT SHOULD CLEAR PRECIPITATION OUT OF THE
NORTHEAST, BUT IS FORECAST TO STALL AND MEANDER ACROSS THE CENTRAL
U.S. WITH A WEST-EAST ORIENTATION. A STRENGTHENING LOW LEVEL JET
WILL INCREASE INSTABILITY AND MOISTURE WHILE A SHORTWAVE ALOFT
HELPS PROVIDE LIFT IN THE SOUTH-CENTRAL U.S. WHERE THE FRONT SETS
UP. WITH THE INGREDIENTS FOR HEAVY RAINFALL/FLASH FLOODING IN
PLACE, A SLIGHT RISK WILL BE RAISED FOR THE
OKLAHOMA/KANSAS/MISSOURI/ARKANSAS INTERSECTION. SOME OF THESE AREAS
HAVE WET ANTECEDENT CONDITIONS, OR SHOULD BY THAT TIME. THIS FRONT
IS FORECAST TO LINGER AND ONLY GRADUALLY PRESS SOUTH INTO EARLY
NEXT WEEK, SO ADDITIONAL FLOOD RISKS ARE POSSIBLE ESPECIALLY IF
ROUNDS OF RAIN REPEAT OVER SIMILAR AREAS. FARTHER EAST, SCATTERED
THUNDERSTORMS THAT TEND TO BE DIURNALLY DRIVEN ARE LIKELY IN THE
SOUTHEAST (INCLUDING FLORIDA) FOR MULTIPLE DAYS. RAIN CHANCES MAY
INCREASE EARLY NEXT WEEK ACROSS THE OHIO VALLEY INTO THE MID-
ATLANTIC AND NORTHEAST, BUT WITH PLENTY OF QUESTIONS IN THE
DETAILS. ELSEWHERE, THE NORTHERN ROCKIES AND HIGH PLAINS COULD SEE
SOME PRECIPITATION LATE FRIDAY INTO SATURDAY, 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 AND PERHAPS OVER 110, WHILE HEAT
INDICES SHOULD BE OVER 100 IN THE SOUTHERN PLAINS TO LOWER
MISSISSIPPI VALLEY. INTO EARLY NEXT WEEK, HEAT AND HUMIDITY SHOULD
EASE A BIT IN PARTS OF THE SOUTH AS THE UPPER TROUGH DIGS A BIT.
BUT UPPER RIDGING BEHIND IT WILL LIKELY STRETCH WARM TEMPERATURE
ACROSS THE WEST COAST, WHICH COULD BE WELL ABOVE AVERAGE
PARTICULARLY IN THE PACIFIC NORTHWEST.
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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