735
FXUS02 KWBC 101845
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 PM EDT SAT JUN 10 2023
VALID 12Z TUE JUN 13 2023 - 12Z SAT JUN 17 2023
...HEAVY RAIN AND STRONG STORMS EXPECTED FROM THE CENTRAL PLAINS
TO THE MID-SOUTH, AND SUMMER HEAT BUILDS FROM TEXAS TO THE LOWER
MISSISSIPPI VALLEY...
..SYNOPTIC OVERVIEW
A WELL-DEFINED CLOSED UPPER LOW IS FORECAST TO BE IN PLACE ACROSS
THE GREAT LAKES TUESDAY AS A SHORTWAVE DROPS SOUTH FROM THE HUDSON
BAY REGION. THIS WILL SPUR SURFACE CYCLOGENESIS ACROSS THE OHIO
VALLEY EARLY IN THE WEEK WITH A TRAILING COLD FRONT EXITING THE
EAST COAST TUESDAY, AND THIS WILL LIKELY PROLONG A PERIOD OF
WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE NORTHEAST. A
SECOND CLOSED UPPER LOW ACROSS THE SOUTHWESTERN U.S. EARLY IN THE
WEEK IS EXPECTED TO EVOLVE INTO A TROUGH AND ENERGIES SHOULD REACH
THE CENTRAL/SOUTHERN PLAINS BY WEDNESDAY, AND THAT WILL LIKELY
SUPPORT A WAVY FRONT. SLOW SYSTEM TRANSLATION AND RETURN
MOISTURE/INSTABILITY OFFERS A THREAT FOR WIDESPREAD SHOWERS AND
STRONG TO SEVERE STORMS FROM THE SOUTHERN PLAINS EASTWARD ACROSS
THE MID-SOUTH/SOUTH THROUGH THE SOUTHERN APPALACHIANS FOR THE
REMAINDER OF THE WEEK WITH EPISODES OF HEAVY RAINFALL POSSIBLE,
WITH BUILDING HEAT AND HUMIDITY TO THE SOUTH OF THE FRONTAL
ZONE/CONVECTION FROM TEXAS TO THE LOWER MISSISSIPPI VALLEY.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THE WPC MEDIUM RANGE GUIDANCE SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE BLEND OF REASONABLY WELL CLUSTERED GUIDANCE FROM THE 06
UTC GFS AND 00 UTC ECMWF/UKMET AND SUPPORTIVE GEFS/ECMWF ENSEMBLE
MEAN GUIDANCE ALONG WITH 13 UTC NATIONAL BLEND OF MODELS VALID FOR
EARLY TO MID NEXT WEEK IN AN OVERALL PATTERN WITH SEEMINGLY ABOVE
NORMAL PREDICTABILITY. THE 00 UTC CANADIAN ALTERNATELY DEVELOPED A
MORE AMPLIFIED UPPER TROUGH/WEATHER FOCUS SOLUTION THAN MOST OTHER
GUIDANCE OVER THE WEST MID-LATER NEXT WEEK VERSUS ALLOWING HEIGHT
FALLS TO INSTEAD WORK MORE EASTWARD OVER THE ROCKIES INTO THE HIGH
PLAINS. HOWEVER, THE 12 UTC CANADIAN HAS TRENDED STRONGLY TOWARD
THE PREFERRED COMPOSITE SOLUTION THAT REMAINS SUPPORTED BY LATEST
12 UTC GUIDANCE, BOLSTERING FORECAST CONFIDENCE.
..WEATHER/HAZARDS HIGHLIGHTS
THE CLOSED LOW OVER THE GREAT LAKES AND TRAILING SURFACE COLD
FRONT CROSSING THE EAST COAST WILL ADVECT COPIOUS MOISTURE
NORTHWARD ACROSS THE NORTHEAST, AND IN COMBINATION WITH AMPLE
INSTABILITY WILL LIKELY PRODUCE STORMS WITH LOCALLY HEAVY
RAINFALL, WITH A MARGINAL RISK OF EXCESSIVE RAINFALL IN EFFECT FOR
TUESDAY ACROSS EASTERN NEW ENGLAND. HOWEVER, THE MAIN FOCUS FOR
HEAVY RAINFALL IS EXPECTED FROM THE CENTRAL PLAINS TO THE
TENNESSEE RIVER VALLEY AND THE SOUTHERN APPALACHIANS FOR THE
WEDNESDAY THROUGH FRIDAY TIME PERIOD, WHERE AN AXIS OF 1-3 INCH
RAINFALL TOTALS WITH LOCALLY HIGHER AMOUNTS IS LIKELY GIVEN
POTENTIAL FOR SLOW MOTIONS AND TRAINING. MOISTURE ADVECTION FROM
THE GULF OF MEXICO WILL INTERSECT A QUASI-STATIONARY/WARM FRONTAL
BOUNDARY AND SHORTWAVE ENERGY ALOFT WILL ALSO AID IN ASCENT. A
FEW MESOSCALE CONVECTIVE COMPLEXES ARE LIKELY TO DEVELOP NEAR THIS
BOUNDARY AND RESULT IN HIGHER RAINFALL RATES THAT COULD RESULT IN
INSTANCES OF FLASH FLOODING, AND THUS A SLIGHT RISK OF EXCESSIVE
RAINFALL IS PLANNED FOR BOTH DAY 4 AND 5 FROM EASTERN OKLAHOMA TO
NORTHERN GEORGIA WHERE DETERMINISTIC AND ENSEMBLE GUIDANCE ALONG
WITH THE NBM CONTINUE TO INDICATE A MORE CONCENTRATED SIGNAL FOR
HIGHER QPF.
IN TERMS OF TEMPERATURES, THE MAIN STORY THAT WILL MAKE HEADLINES
WILL BE THE BUILDING HEAT AND HUMIDITY ACROSS MUCH OF TEXAS AND
INTO SOUTHERN PORTIONS OF THE DEEP SOUTH STATES, WITH THE HOTTEST
WEATHER OF THE SEASON EXPECTED THUS FAR. WIDESPREAD MID-UPPER 90S
ARE LIKELY FROM NORTHERN FLORIDA TO LOUISIANA, AND 100-110 DEGREES
FOR MUCH OF CENTRAL AND SOUTHERN TEXAS AWAY FROM THE COASTAL
AREAS. SOME HEAT INDICES ON THE ORDER OF 110-120 DEGREES ARE
POSSIBLE ACROSS PORTIONS OF DEEP SOUTH TEXAS FOR THE MIDDLE TO END
OF THE WEEK WITH DEWPOINTS WELL INTO THE 70S. THIS HEAT WAVE WILL
LIKELY HAVE SOME STAYING POWER BEYOND NEXT SATURDAY BASED ON THE
LATEST FORECASTS FROM THE CLIMATE PREDICTION CENTER. ELSEWHERE,
EXPECT PLEASANTLY COOLER CONDITIONS COMPARED TO AVERAGE ACROSS
MUCH OF THE SOUTHWEST TO THE CENTRAL ROCKIES, AND ALSO FOR MUCH OF
THE EASTERN U.S. FOR THE MIDDLE OF THE WEEK, AND THEN A GRADUAL
WARMING TREND GOING INTO THURSDAY AND BEYOND.
SCHICHTEL/HAMRICK
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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