055
FXUS02 KWBC 230701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
301 AM EDT FRI JUN 23 2023
VALID 12Z MON JUN 26 2023 - 12Z FRI JUN 30 2023
...PROLONGED HEAT WAVE CONTINUES ACROSS TEXAS AND SOUTHEASTERN NEW
MEXICO AND WILL EXPAND NORTHEAST NEXT WEEK...
..OVERVIEW
THE OVERALL UPPER LEVEL PATTERN WILL REMAIN FAIRLY STAGNANT
THROUGH THE PERIOD WITH A STRONG RIDGE OVER THE SOUTH-CENTRAL U.S.
AND MEAN UPPER LOW/TROUGHING OVER THE EAST AND WEST COASTS. THE
RIDGE IS RESPONSIBLE FOR EXCESSIVE HEAT IN THE SOUTHERN PLAINS,
AND HEAT WILL GRADUALLY EXPAND EAST AND NORTH INTO THE LOWER
MISSISSIPPI VALLEY AND PARTS OF THE MIDDLE MISSISSIPPI VALLEY AND
CENTRAL PLAINS BY MID-NEXT WEEK. ADDITIONAL SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO FOCUS IN THE EASTERN THIRD OF THE
COUNTRY AS A FEW SURFACE LOW PRESSURE SYSTEMS MOVE ACROSS THE
REGION AND ALSO OUT FROM THE WEST INTO THE NORTH-CENTRAL U.S..
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THE LATEST SOLUTIONS OF THE GFS/ECMW/CANADIAN AND GEFS/ECMWF
ENSEMBLE MEANS SEEM BEST CLUSTERED FOR THE 3-7 DAY FORECAST PERIOD
AND A COMPOSITE BLEND IS PREFERRED ALONG WITH WPC CONTINUITY AND
THE NATIONAL BLEND OF MODELS. THE OVERALL SLIGHTLY MORE
PROGRESSIVE UKMET SOLUTION LESS LIKELY GIVEN AMPLIFIED AND SLOW
MOVING/REPEAT FLOW HISTORY.
..WEATHER/HAZARDS HIGHLIGHTS
A DEEP LAYERED LOW PRESSURE SYSTEM WITH WRAPPING MOISTURE WILL
SLOWLY SHIFT A PROTRACTED RAIN/CONVECTION FOCUS FROM THE GREAT
LAKES AND UPPER OHIO VALLEY TO THE NORTH-CENTRAL
APPALACHIANS/MID-ATLANTIC AND NORTHEAST MONDAY INTO THURSDAY, WITH
SOME LOCALLY HEAVY AMOUNTS POSSIBLE GIVEN POTENTIAL FOR
TRAINING/REPEAT ACTIVITY WITH SLOW SYSTEM TRANSLATIONS AND GOOD
DYNAMICAL SUPPORT. CONVECTION ALSO LOOKS TO OVERSPREAD DOWN OVER
MUCH OF THE EAST EARLY-MID NEXT WEEK WITH TRAILING FRONTAL PUSH,
WITH STRONG TO SEVERE WEATHER ALSO A POSSIBILITY. A WPC EXCESSIVE
RAINFALL OUTLOOK (ERO) "MARGINAL RISK" HAS BEEN MAINTAINED FOR
MUCH OF THE EAST MONDAY AND LINGERING ACROSS THE NORTHERN
MID-ATLANTIC/NORTHEAST TUESDAY AS THERE MAY BE MULTIPLE
OPPORTUNITIES FOR LOCALLY HEAVY RAIN WITH SCATTERED TO WIDESPREAD
STORMS IN AN UNSTABLE ENVIRONMENT. EMBEDDED "SLIGHT RISKS" ARE
QUITE POSSIBLE WITH FUTURE ERO UPDATES GIVEN AMPLE EARLY SUMMER
UPPER LOW/TROUGH DEVELOPMENT ONCE THE GUIDANCE SIGNAL BECOMES
STRONGER FOR A GIVEN LOCATION. BY TUESDAY AND WEDNESDAY, THE FRONT
SHOULD PUSH SLOWLY EASTWARD WITH DRYING BEHIND THE FRONT, WHILE
ADDITIONAL LEADING ROUNDS OF RAIN AND THUNDERSTORMS CONTINUE FOR
THE EASTERN SEABOARD.
MEANWHILE UPSTREAM, THE EJECTION OF SPLITTING/LEAD UPPER TROUGH
ENERGIES ACROSS THE WEST WILL BRING SCATTERED SHOWERS AND STORM
CHANCES ACROSS THE NORTHERN GREAT BASIN/NORTHWEST EARLY NEXT WEEK.
ACTIVITY WILL INCREASINGLY SPREAD DOWNSTREAM TO THE NORTHERN
ROCKIES/PLAINS WHERE AN ERO "MARGINAL RISK" IS PLANNED FOR TUESDAY
TO ADDRESS POTENTIAL TRAINING/REPEAT CELL RUNOFF CONCERNS, WITH
ACTIVITY THEN EXPANDING INTO THE MID-UPPER MISSISSIPPI VALLEY
THROUGH NEXT MIDWEEK.
IN TERMS OF TEMPERATURES, THERE IS REALLY NO END IN SIGHT FOR THE
EXCESSIVE HEAT THAT HAS PLAGUED PARTICULARLY TEXAS/SOUTHEASTERN
NEW MEXICO IN RECENT DAYS. TEMPERATURES OVER 100F AND HEAT INDICES
MUCH HIGHER WILL CONTINUE EXPANDING EAST INTO THE LOWER
MISSISSIPPI VALLEY AND NORTH TOWARD THE CENTRAL PLAINS NEXT WEEK.
THE CURRENT FORECAST CALLS FOR TEMPERATURES EXCEEDING NEAR TO JUST
ABOVE 100F IN OKLAHOMA/KANSAS/ARKANSAS BY WEDNESDAY-THURSDAY.
SEVERAL RECORD TEMPERATURES COULD BE SET OR TIED, AS TEMPERATURES
NEARING OR EXCEEDING 110 DEGREES COULD AGAIN OCCUR IN WESTERN AND
SOUTHERN TEXAS. THE DESERT SOUTHWEST STARTS TO SEE TEMPERATURES
WELL OVER 100F NEXT WEEK TOO, THOUGH NOT REALLY ANOMALOUS FOR THIS
TYPICALLY HOTTEST TIME OF THE YEAR THERE. MEANWHILE THE WEST
SHOULD SEE SLIGHTLY COOLER THAN NORMAL TEMPERATURES PARTICULARLY
FOR HIGHS WITH THE BOUTS OF UPPER TROUGHING ALOFT. THE EAST LOOKS
TO BE SLIGHTLY COOLER THAN NORMAL OVERALL AS WELL TO CONTINUE A
RECENT TREND, WITH TEMPERATURES 5-10+ DEGREES BELOW NORMAL FROM
THE GREAT LAKES REGION THROUGH THE NORTH-CENTRAL
APPALACHIANS/MID-ATLANTIC.
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 AND HEAT INDICES 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
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