007
FXUS02 KWBC 170700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT SAT AUG 17 2024
VALID 12Z TUE AUG 20 2024 - 12Z SAT AUG 24 2024
...HAZARDOUS HEAT TO PERSIST FROM THE SOUTHERN PLAINS TO THE
WEST-CENTRAL GULF COAST NEXT WEEK...
..OVERVIEW
AN OMEGA-STYLE BLOCKY UPPER PATTERN WILL DEVELOP AND LINGER NEXT
WEEK. THIS WILL BE HIGHLIGHTED BY A BUILDING UPPER HIGH CENTERED
OVER THE SOUTHERN HIGH PLAINS THAT WILL PROMOTE HAZARDOUS HEAT FROM
THE SOUTHERN PLAINS TO THE CENTRAL GULF COAST. UPSTREAM, AMPLIFIED
UPPER TROUGHING IS FORECAST TO MEANDER NEAR/OFF THE WEST COAST.
DOWNSTREAM, AN AMPLIFIED MEAN UPPER TROUGH WILL WORK INTO AND
PERSIST OVER AN UNSETTLED EAST-CENTRAL TO EASTERN U.S..
..GUIDANCE/PREDICTABILITY ASSESSMENT
FORECAST SPREAD AND UNCERTAINTY IN GUIDANCE CONTINUES TO HOLD AT
BELOW NORMAL THRESHHOLDS THROUGH MEDIUM RANGE TIME SCALES FOR NEXT
WEEK OVER MUCH OF OUR FINE NATION. A FULLY INCLUSIVE MODEL AND
ENSEMBLE MEAN COMPOSITE BLEND ALONG WITH THE NATIONAL BLEND OF
MODELS SEEMS TO PROVIDE A SOLID DETERMINISTIC FORECAST BASE AND
RANGES OF SOLUTIONS AND POTENTIAL HAZARDS, ALBEIT WITH TYPICALLY
LESS PREDICTABLE SMALLER SCALE WARM SEASON FEATURES AND LOCAL
WEATHER FOCUS TO BETTER ADDRESS AT CLOSER TIME SCALES.
..WEATHER/HAZARDS HIGHLIGHTS
AN EAST-CENTRAL TO EASTERN U.S. UPPER TROUGH OFFERS SOME LINGERING
UNSETTLED CONDITIONS, BUT MUCH OF EARLIER PERIOD RAINS ARE
EXPECTED TO TAPER OFF BY MIDWEEK AS SURFACE HIGH PRESSURE BUILDS
IN BEHIND THE COLD FRONT(S) AND IN THE WAKE OF ERNESTO AS LIFTED
WELL OFFSHORE. HOWEVER, TRAILING FRONTS SLATED TO STALL FARTHER
SOUTH ACROSS FLORIDA AND VICINITY WILL MAINTAIN PERIODIC
THUNDERSTORM CHANCES THERE. FLOODING ISSUES ARE A POSSIBILITY IF
HEAVY RAIN FALLS IN URBAN AREAS. THIS FRONT MOVES SLOWLY AS IT
BENDS BACK TO THE WEST ATOP THE CENTRAL GULF COAST AND BACK NORTH
INTO THE PLAINS. SCATTERED STORMS ARE POSSIBLE NEAR THE FRONT AS
IMPULSES "RIDE THE RIDGE" ALOFT, BUT WITH GENERALLY LOW CONFIDENCE
IN PLACEMENT STILL AT THIS TIME.
MEANWHILE, MONSOONAL CONVECTION WILL AFFECT THE SOUTHWEST/FOUR
CORNERS STATES NEXT WEEK WITH MOIST SOUTHERLY FLOW WEST OF THE
UPPER RIDGE AXIS. THE WPC DAY 4/5 EXCESSIVE RAINFALL OUTLOOKS HAVE
MARGINAL RISKS AREAS ISSUED FOR TUESDAY AND WEDNESDAY OVER
PORTIONS OF ARIZONA, UTAH, SOUTHEAST CALIFORNIA, SOUTHERN NEVADA
AND COLORADO. STORMS WITH EMBEDDED HEAVY RAIN COULD CAUSE ISOLATED
FLOODING, PARTICULARLY IN VULNERABLE AREAS.
MEANWHILE, UPPER TROUGH AMPLIFICATION PROXIMITY ALONG/OFF THE WEST
COAST PORTENDS A COOLER AND WETTER PATTERN FOR THE NORTHWEST. SOME
RAINS ARE ALSO FORECAST TO BROADLY FOCUS DOWNSTREAM ACROSS THE U.S.
NORTHERN TIER AS THE WEEK PROGRESSES. SOME CONVECTION MAY BREAK OUT
ALONG/AHEAD OF RELATIVELY SLOW MOVING FRONTAL SYSTEMS ACROSS THE
NORTH-CENTRAL U.S. AS NEXT WEEK PROGRESSES, BUT FOCUS IS UNCERTAIN.
UPPER RIDGING OVER THE SOUTH-CENTRAL U.S. WILL MAINTAIN ABOVE
NORMAL TEMPERATURES BY 5-15 DEGREES FROM THE HIGH PLAINS EAST INTO
THE WEST-CENTRAL GULF COAST. HIGHS WELL INTO THE 100S IN MUCH OF
TEXAS COULD SET DAILY RECORDS AND HIGH DEWPOINTS SHOULD PRODUCE
HEAT INDICES LIKELY ABOVE 110 DEGREES. LOW TEMPERATURES IN THE
UPPER 70S TO LOW 80S WILL EXACERBATE HEAT STRESS AND COULD SET
RECORDS FOR WARM MINIMUM TEMPERATURES. EXPERIMENTAL HEATRISK
CONTINUES TO SHOW MAJOR TO EXTREME IMPACTS FROM THIS HEAT WAVE.
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 FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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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