106
FXUS02 KWBC 241903
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SAT JUN 24 2023
VALID 12Z TUE JUN 27 2023 - 12Z SAT JUL 01 2023
...PROLONGED HEAT WAVE ACROSS TEXAS AND SOUTHEASTERN NEW MEXICO
WILL EXPAND NORTHEAST TOWARD THE MID-MISSISSIPPI VALLEY NEXT
WEEK...
...EXCESSIVE RAINFALL POSSIBLE ACROSS THE NORTHERN PLAINS AND
NORTHEAST EARLY-MID NEXT WEEK...
..OVERVIEW
A POTENT AND PERSISTENT UPPER RIDGE WILL NUDGE EASTWARD FROM TEXAS
TO THE LOWER MISSISSIPPI VALLEY THROUGH THE END OF NEXT WEEK WHILE
MEAN UPPER LOW/TROUGHING HOLDS OVER THE EAST AS A
POSITIVELY-TILTED TROUGH OVER THE WEST LIFTS GENERALLY TOWARD THE
NORTHERN PLAINS. A NORTHEASTWARD EXPANSION OF THE EXCESSIVE HEAT
IS EXPECTED UNDERNEATH THE RIDGE FROM THE SOUTHERN PLAINS TO THE
MID-MISSISSIPPI VALLEY AND PORTIONS OF THE CENTRAL PLAINS NEXT
WEEK. WPC AND CPC CONTINUE TO JOINTLY PRODUCE "KEY MESSAGES" FOR
THIS HEATWAVE. MEANWHILE, LOW PRESSURE WAVES UNDERNEATH THE UPPER
TROUGHS WILL FOCUS SHOWERS AND THUNDERSTORMS OVER THE NORTHEAST
AND THE NORTH-CENTRAL U.S.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
MODEL AND ENSEMBLE SOLUTIONS OVERALL REMAIN WELL CLUSTERED NEXT
WEEK, BOLSTERING FORECAST CONFIDENCE. THE MORE UNCERTAIN PART OF
THE FORECAST HAS TO DO WITH THE TIMING OF THE EJECTION OF THE
UPPER TROUGH FROM THE ROCKIES INTO THE NORTHERN U.S. THE ECMWF AND
CMC HAD BEEN ON THE FAST SIDE OF THE GUIDANCE WITH A
BETTER-DEFINED LOW PRESSURE SYSTEM TRACKING TOWARD THE GREAT LAKES
BY ABOUT NEXT WEEKEND, WHEREAS THE GFS HAD BEEN SLOW WITH THE
SYSTEM UP TO THE 06Z RUN. HOWEVER, THE 12Z GFS SUDDENLY FLIPPED
TO A SOLUTION MUCH MORE AGREEABLE WITH THE FASTER GUIDANCE.
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE BLEND OF GFS/ECMWF/CANADIAN MODELS TOGETHER WITH THEIR
ENSEMBLE MEANS TUESDAY-THURSDAY TO PROVIDE MAXIMUM DETAIL
CONSISTENT WITH A PATTERN WITH SEEMINGLY ABOVE NORMAL
PREDICTABILITY. MORE OF THE ENSEMBLE MEAN SOLUTIONS WERE INCLUDED
FOR DAYS 6 AND 7 TO HANDLE TO HIGHER UNCERTAINTY WITH THE TIMING
OF THE TROUGH EJECTION INTO THE NORTHERN U.S. LATE NEXT WEEK. THIS
SOLUTION MAINTAINS GOOD WPC PRODUCT CONTINUITY EXCEPT ACROSS THE
NORTHERN TIER ON DAY 7.
..WEATHER/HAZARDS HIGHLIGHTS
THE NEXT LOW PRESSURE SYSTEM OF CONCERN WILL MOVE ACROSS THE GREAT
LAKES AS THE MEDIUM-RANGE FORECAST PERIOD BEGINS ON TUESDAY. AMPLE
MOISTURE WILL LIKELY SUPPORT WIDESPREAD PRECIPITATION FOR THE
ENTIRE NORTHEASTERN U.S. INTO THE MID-ATLANTIC. LOCALLY HEAVY
RAINFALL WILL BE POSSIBLE WITH POTENTIAL TRAINING AND EMBEDDED
THUNDERSTORMS ASSOCIATED WITH THIS SYSTEM THAT SHOULD AGAIN PROVE
TO BE SLOW TO MOVE ON. A WPC EXCESSIVE RAINFALL OUTLOOK (ERO)
"MARGINAL RISK" AREA IS MAINTAINED OVER THE NORTHEAST IN A
SLOW-TO-EVOLVE FLOW PATTERN IN AN AREA THAT HAD EXPERIENCED
ANTECEDENT RAINFALL. EMBEDDED "SLIGHT RISK" AREAS REMAIN POSSIBLE
IN FUTURE ERO UPDATES WHEN CONFIDENCE IN THE LOCATION OF HEAVIER
RAINFALL TOTALS INCREASES. MODELS GENERALLY AGREE THAT THE TROUGH
WILL MAKE A SLOW EASTWARD PROGRESSION THROUGH THE END OF NEXT WEEK
WITH THE HEAVIEST RAINS PROBABLY SLIDE OFF NEW ENGLAND BY FRIDAY
BUT WITH LINGERING RESIDUAL SCATTERED ACTIVITIES INTO THE WEEKEND.
MEANWHILE, THE EJECTION OF UPPER TROUGH ENERGIES OUT FROM THE WEST
WILL BRING SCATTERED SHOWERS AND STORM CHANCES, WITH ACTIVITY
LIKELY TO BE ON THE INCREASE AND SPREAD DOWNSTREAM TO THE NORTHERN
ROCKIES AND NORTHERN PLAINS, AND HEAVY RAINFALL MAY BE A CONCERN.
THERE IS A PLANNED "MARGINAL RISK" OF EXCESSIVE RAINFALL FOR PARTS
OF THIS REGION TUESDAY AND WEDNESDAY TO ADDRESS POTENTIAL
TRAINING/REPEAT CELL RUNOFF CONCERNS. PRECIPITATION WILL SPREAD
INTO THE UPPER MIDWEST AND OHIO AND TENNESSEE VALLEYS MID-TO-LATE
NEXT WEEK AS THE SYSTEM PROGRESSES TO THE EAST.
IN TERM OF TEMPERATURES, EXCESSIVE HEAT WILL CONTINUE TO PLAGUE
THE SOUTH-CENTRAL U.S. THROUGH AT LEAST NEXT WEEK WITH A MID-WEEK
EXPANSION NORTH AND EAST ACROSS PORTIONS OF THE CENTRAL PLAINS AND
INTO THE MID- AND LOWER MISSISSIPPI VALLEY. THE HEAT WILL BE
OPPRESSIVE WITH WIDESPREAD HIGH TEMPERATURES EXCEEDING 100 DEGREES
AND HEAT INDICES AS HIGH AS 120 DEGREES. HEAT INDICES MAY EVEN
EXCEED 120 DEGREES IN SOME LOCATIONS IN SOUTH TEXAS. SEVERAL
TEMPERATURE RECORDS ARE IN DANGER OF BEING BROKEN DURING THIS
SIGNIFICANT HEAT WAVE. THE DESERT SOUTHWEST WILL ALSO EXPERIENCE
TEMPERATURES WELL OVER 100 DEGREES NEXT WEEK, BUT THAT IS NOT
REALLY ANOMALOUS FOR THIS TIME OF YEAR. ELSEWHERE IN THE COUNTRY,
NEAR NORMAL HIGH TEMPERATURES ARE FORECAST WITH BELOW NORMAL HIGHS
LIKELY IN AREAS OF PRECIPITATION EACH DAY.
KONG/SCHICHTEL
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, EXPERIMENTAL 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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page