711
FXUS02 KWBC 140736
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
336 AM EDT TUE JUL 14 2026
VALID 12Z FRI JUL 17 2026 - 12Z TUE JUL 21 2026
...DANGEROUS HEAT CONTINUES ACROSS THE NORTH-CENTRAL U.S. THROUGH
THE END OF THE WEEK...
..OVERVIEW
A STRONG UPPER RIDGE OVER THE CENTRAL U.S. WILL CONTINUE TO CAUSE
DANGEROUS HEAT ACROSS THE NORTHERN PLAINS AND MIDWEST LATE WEEK.
THE EASTERN PORTION OF THE RIDGE LIKELY JOINING UP WITH A
SUBTROPICAL ATLANTIC RIDGE SHOULD LEAD TO HOT TEMPERATURES ACROSS
THE OHIO VALLEY TO MID-ATLANTIC FRIDAY AS WELL. AN UPPER TROUGH
POKING INTO THE NORTHEAST SHOULD GRADUALLY SHIFT THE HEAT SOUTHWARD
AND BRING SOME RELIEF TO NORTHERN AREAS OVER THE WEEKEND AND EARLY
NEXT WEEK. MEANWHILE, MONSOONAL MOISTURE WILL CONTINUE TO STREAM
IN UNDERNEATH THE UPPER RIDGE, PRODUCING ROUNDS OF DIURNALLY
DRIVEN SHOWERS AND STORMS ACROSS THE SOUTHWEST, FOUR CORNERS
STATES, AND NORTHWARD INTO THE NORTHERN ROCKIES/HIGH PLAINS.
ADDITIONALLY, ENERGIES ON THE NORTHERN SIDE OF THE RIDGE COULD ALSO
LEAD TO ROUNDS OF RAIN AND THUNDERSTORMS IN THE GREAT LAKES/OHIO
VALLEY TO EAST COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE HAS BEEN REASONABLY AGREEABLE ON THE LARGE SCALE
PATTERN, INCLUDING THE UPPER RIDGE ATOP THE ROCKIES TO PLAINS AND
STRETCHING INTO THE SOUTHEASTERN U.S. AS THE PERIOD BEGINS FRIDAY.
TROUGHING IN THE NORTHEAST IS FORECAST TO GRADUALLY DEEPEN OVER THE
WEEKEND AND EARLY NEXT WEEK, WHICH SHUNTS THE UPPER RIDGE AXIS
WESTWARD A BIT INTO THE INTERMOUNTAIN WEST. HOWEVER, SHORTWAVES
WITHIN THE TROUGH HAVE BEEN QUESTIONABLE, AFFECTING THE TROUGH'S
DEPTH AS WELL AS QPF AND FRONTAL PLACEMENT. MEANWHILE, MODELS HAVE
STRUGGLED WITH AN UPPER LOW IN THE EASTERN PACIFIC OFFSHORE OF THE
PACIFIC NORTHWEST. WITH THIS FEATURE, THE 12Z AND NEWER 00Z MODEL
CYCLES ARE SHOWING OKAY CONSENSUS ON A MIDDLE GROUND TIMING
COMPARED TO LAST NIGHT, BRINGING THE UPPER LOW INTO
WASHINGTON/BRITISH COLUMBIA AROUND SATURDAY. THE EXCEPTION IS THE
ECMWF, WHICH WAS ABOUT A DAY FASTER THAN THE OTHER DYNAMICAL AND AI
MODELS. THIS LOW MAY MOVE EAST ACROSS SOUTHERN CANADA AND BECOME
ONE OF THE SHORTWAVES MOVING THROUGH THE GREAT LAKES/NORTHEAST
TROUGH, EXACERBATING THE UNCERTAINTY THERE. ELSEWHERE, THERE IS
STILL SOME SIGNAL ESPECIALLY FROM AIFS AND ICON ENSEMBLE MEMBERS
AND THE AIGFS SHOWING A TROPICAL LOW IN THE NORTHEASTERN GULF EARLY
NEXT WEEK, WHICH BEARS WATCHING.
THE WPC FORECAST WAS BASED ON A NON-ECMWF BLEND, CONSIDERING ITS
FASTER TRACK OF THE NORTHWEST LOW. AS THE PERIOD PROGRESSED,
INCREASED THE PROPORTION OF ENSEMBLE MEANS TO OVER HALF BY DAY 7
AMID INCREASING MODEL SPREAD.
..WEATHER/HAZARDS HIGHLIGHTS
HAZARDOUS HEAT IS FORECAST TO PERSIST IN THE NORTH-CENTRAL U.S.
INTO LATE WEEK UNDER THE UPPER RIDGE. CONTINUED WELL ABOVE NORMAL
MAXIMUM AND MINIMUM TEMPERATURES WILL LEAD TO MAJOR TO EXTREME
HEATRISK IN THE NORTHERN/CENTRAL PLAINS AND MIDWEST. WPC CONTINUES
TO UPDATE HEAT KEY MESSAGES FOR THIS EVENT, WHICH CAN BE FOUND ON
OUR HOMEPAGE. THE HOT CONDITIONS SHOULD SLOWLY EASE IN THE NORTHERN
STATES AND SHIFT SOUTHWARD INTO EARLY NEXT WEEK. FARTHER EAST, THE
UPPER RIDGE COMBINING WITH SUBTROPICAL ATLANTIC RIDGING IN THE
SOUTHEAST AND FLORIDA WILL PROMOTE WARMER THAN AVERAGE TEMPERATURES
AS FAR NORTH AS THE OHIO VALLEY AND MID-ATLANTIC FRIDAY, ALSO
MOVING GRADUALLY SOUTHWARD THROUGH THE PERIOD AS THE NORTHEASTERN
U.S. UPPER TROUGH PUSHES A COLD FRONT OR TWO SLOWLY SOUTH.
MEANWHILE, THE SOUTHWESTERN TO SOUTH-CENTRAL U.S. COULD SEE
SLIGHTLY BELOW AVERAGE TEMPERATURES AS AMPLE MOISTURE LEADS TO
CLOUDS AND RAIN/THUNDERSTORMS. CONTINUED SOUTHERLY FLOW UNDER THE
BROAD UPPER RIDGE WILL DRAW SIGNIFICANT MONSOONAL MOISTURE INTO THE
SOUTHWEST AND INTERMOUNTAIN WEST TO ROCKIES. THIS MOISTURE WILL
LEAD TO SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WITH THE
POTENTIAL TO PRODUCE HEAVY RAINFALL AND LOCALIZED FLASH FLOODING.
SENSITIVE PLACES SUCH AS BURN SCARS, STEEP TERRAIN, ETC., WOULD BE
THE MOST VULNERABLE TO ANY FLOODING CONCERNS THAT MAY DEVELOP.
BROAD MARGINAL RISKS OF EXCESSIVE RAINFALL REMAIN IN PLACE FROM THE
SOUTHWEST ACROSS PARTS OF THE INTERMOUNTAIN WEST NORTH TO MONTANA
FOR DAY 4-5 (FRIDAY-SATURDAY). THE MARGINAL ALSO ENCOMPASSES
WESTERN TEXAS, WHICH WILL LIKELY HAVE AMPLE RAINFALL IN THE SHORT
RANGE PERIOD CAUSING EXTREMELY WET ANTECEDENT CONDITIONS. FOR DAY
4/FRIDAY, A SLIGHT RISK IS IN PLACE FOR MUCH OF ARIZONA AND
VICINITY WHERE ENHANCED RAINFALL AND FLOODING THREATS ARE
RELATIVELY MORE LIKELY. MONSOONAL MOISTURE SHOULD PERSIST INTO
EARLY NEXT WEEK.
MULTIPLE ROUNDS OF RAIN/THUNDERSTORMS ARE ALSO POSSIBLE FROM THE
GREAT LAKES AND OHIO VALLEY TO THE EAST COAST AS SHORTWAVES AND
FRONTAL SYSTEMS FOCUS MOISTURE THROUGH THE PERIOD. MARGINAL RISKS
OF FLASH FLOODING ARE DELINEATED FOR THE GREAT LAKES/OHIO VALLEY TO
APPALACHIANS ON FRIDAY, AND STRETCHING INTO THE MID-ATLANTIC ON
SATURDAY.
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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