476
FXUS02 KWBC 240700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 AM EDT THU AUG 24 2023
VALID 12Z SUN AUG 27 2023 - 12Z THU AUG 31 2023
***STILL REMAINING HOT AND HUMID FOR THE GULF COAST REGION THROUGH
EARLY NEXT WEEK WITH SOME PLACES LIKELY RECORDING THE WARMEST
AUGUST ON RECORD***
..SYNOPTIC OVERVIEW
WELCOMED RELIEF FROM THE EXTREME HEAT IS IN STORE FOR THE
NORTH-CENTRAL U.S. BY THE WEEKEND AS THE ONGOING MAJOR LATE SUMMER
HEATWAVE ABATES AND THE UPPER RIDGE IS SUPPRESSED TO THE SOUTH.
THE AREAL COVERAGE OF EXCESSIVE AND RECORD-BREAKING HEAT WILL
SHRINK WITH IT, BECOMING MORE LIMITED TO THE GULF COAST STATES BY
THE WEEKEND WHERE ADDITIONAL DAILY RECORD HIGHS ARE LIKELY. THE
UPPER TROUGH THAT IS FORECAST TO AMPLIFY OVER THE NORTHEASTERN
QUADRANT OF THE COUNTRY NEXT WEEK NOT ONLY WILL BE RESPONSIBLE FOR
BRINGING THE COOLER TEMPERATURES BUT ALSO A THREAT OF HEAVY RAIN
FOR THE CENTRAL HIGH PLAINS THIS WEEKEND, FOLLOWED BY THE
CAROLINAS DURING THE FIRST HALF OF NEXT WEEK.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE REMAINS IN VERY GOOD AGREEMENT ACROSS
THE CONTINENTAL U.S. THROUGH SUNDAY WITH GENERALLY ABOVE AVERAGE
FORECAST CONFIDENCE ON THE SYNOPTIC SCALE. THEREFORE A
MULTI-DETERMINISTIC MODEL BLEND SUFFICES AS A STARTING POINT IN
THE FORECAST PROCESS FOR FRONTS/PRESSURES THROUGH MONDAY NIGHT.
LOOKING AHEAD TO TUESDAY AND WEDNESDAY, THE MODEL GUIDANCE IS
STILL IN OVERALL DECENT AGREEMENT, AND THE GUIDANCE HAS CONVERGED
ON TIMING FOR THE STRONG UPPER TROUGH DEVELOPING OVER THE GREAT
LAKES/INTERIOR NORTHEAST BY WEDNESDAY, AND THERE IS IMPROVED MODEL
CONSENSUS FOR FRANKLIN AS THIS SYSTEM REMAINS WELL OFF THE EAST
COAST. ENSEMBLE MEANS ACCOUNTED FOR ABOUT 40% OF THE MODEL BLEND
BY NEXT THURSDAY, WHILST STILL KEEPING SIZABLE PORTIONS OF THE
GFS/ECMWF SOLUTIONS.
..WEATHER/HAZARDS HIGHLIGHTS
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BE PREVALENT FROM
EASTERN COLORADO AND EXTENDING INTO PORTIONS OF EASTERN NEW MEXICO
AND NORTHWESTERN TEXAS SUNDAY AND INTO MONDAY AS A COUPLE OF
CONVECTIVE COMPLEXES ARE LIKELY TO DEVELOP. A MARGINAL RISK AREA
IS IN EFFECT FOR BOTH OF THESE DAYS WHERE SOME SLOW MOVING STORMS
COULD DEVELOP AND PRODUCE LOCALIZED INSTANCES OF FLOODING. ACROSS
THE EASTERN U.S., THE COLD FRONT WILL INTERCEPT A MOIST AND
UNSTABLE AIRMASS ACROSS THE CAROLINAS WITH SCATTERED TO NUMEROUS
SHOWERS AND STORMS EXPECTED TO DEVELOP, AND A MARGINAL RISK AREA
IS IN EFFECT FROM THE SOUTHERN APPALACHIANS TO THE SOUTH CAROLINA
COAST. UNSETTLED WEATHER CONDITIONS ARE LIKELY TO CONTINUE ACROSS
PORTIONS OF THE SOUTHEAST U.S. GOING INTO THE MIDDLE OF NEXT WEEK,
WITH CONVECTION INCREASING ACROSS MUCH OF FLORIDA. TROPICAL
CONVECTION APPEARS TO STREAM TOWARD THE FLORIDA PENINSULA FROM THE
SOUTHWEST AS THE NATIONAL HURRICANE CENTER IS MONITORING THE
POTENTIAL FOR A TROPICAL SYSTEM TO DEVELOP OVER THE EASTERN GULF
OF MEXICO EARLY NEXT WEEK, BUT FOR NOW A MARGINAL RISK IS VALID
FOR ROUGHLY THE SOUTHERN THIRD OF FLORIDA ON MONDAY TO ACCOUNT FOR
THIS POTENTIAL. ELSEWHERE, SHOWERS AND A FEW STORMS ARE LIKELY
FROM THE GREAT LAKES TO NEW ENGLAND FOR THE FIRST HALF OF THE
WEEK, AND WASHINGTON STATE MAY ALSO GET SOME BENEFICIAL RAINFALL
BY TUESDAY AND WEDNESDAY.
ALTHOUGH THE HEATWAVE WILL HAVE CONCLUDED ACROSS THE MIDWEST AND
OHIO VALLEY, IT WILL STILL BE QUITE HOT AND UNCOMFORTABLE FROM
TEXAS TO SOUTH CAROLINA THIS WEEKEND, WITH WIDESPREAD 100+ DEGREE
HIGHS EXPECTED ON SUNDAY ALONG AND SOUTH OF THE INTERSTATE 20
CORRIDOR. THIS MAY ESTABLISH ADDITIONAL DAILY RECORD HIGHS AND
PROBABLY SECURE THE HOTTEST AUGUST ON RECORD FOR MANY GULF COAST
AND DEEP SOUTH CITIES. THE HEAT FINALLY ABATES A LITTLE ACROSS
THE GULF COAST REGION GOING INTO TUESDAY AND WEDNESDAY WITH MAINLY
90S FOR HIGHS EXPECTED FOR THESE SAME AREAS, BUT STILL REMAINING A
FEW DEGREES ABOVE AVERAGE WITH NO SIGN OF FALL-LIKE WEATHER
ANYTIME SOON. UNFORTUNATELY HEAT BUILDS AGAIN ACROSS THE LOWER
ELEVATIONS OF THE DESERT SOUTHWEST WITH SOME 110S LIKELY BY THE
WEEKEND AND EARLY NEXT WEEK, BUT THIS SHOULD ALSO ABATE SOME BY
WEDNESDAY AND BEYOND. ELSEWHERE, TEMPERATURES WILL BE PLEASANT
ACROSS MUCH OF THE NORTHEASTERN QUADRANT OF THE NATION WITH HIGHS
MAINLY IN THE 70S AND 80S AND COMFORTABLE HUMIDITY LEVELS, AND 60S
CLOSER TO THE CANADIAN BORDER.
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 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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