648
FXUS02 KWBC 191900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MON AUG 19 2024
VALID 12Z THU AUG 22 2024 - 12Z MON AUG 26 2024
...HAZARDOUS HEAT TO PERSIST FOR THE SOUTHERN PLAINS INTO THIS
WEEKEND...
..OVERVIEW
THE AMPLIFIED UPPER PATTERN OF A CENTRAL CONUS RIDGE CENTERED OVER
THE SOUTHERN PLAINS WITH TROUGHING OVER THE NORTHEAST INTO THIS
WEEKEND AND A LOW MOVING OVER THE NORTHWEST INTO NEXT WEEK. THIS
PATTERN MAINTAINS HAZARDOUS HEAT OVER TEXAS, MOIST MONSOONAL FLOW
OVER THE SOUTHWEST/FOUR CORNERS, COOLER SURFACE HIGH PRESSURE ALONG
THE EASTERN SEABOARD, AND TROPICAL MOISTURE LURKING NEAR THE GULF
COAST AND ACROSS FLORIDA.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 12Z GLOBAL SUITE IS COMING INTO DECENT AGREEMENT WITH THE
PROGRESS OF THE WESTERN LOW/TROUGH OVER THE WEEKEND WITH A SOMEWHAT
MORE PROGRESSIVE TRACK THAN THE 00Z CONSENSUS. THE 06Z GFS WAS THE
MOST PROGRESSIVE WITH THE ARRIVAL OF THE LOW TO THE NORTHERN PLAINS
BY SUNDAY, SO IT WAS DISREGARDED FROM THE MORNING MODEL PREFERENCE.
HOWEVER, NOW THE 12Z GFS HAS SLOWED CONSIDERABLY AND IS IN LINE
WITH THE 12Z CONSENSUS WITH THE UPPER LOW/TROUGH REACHING THE
EASTERN MT BORDER AROUND 12Z MONDAY.
FOR DAYS 4-7 QPF THE 13Z NBM WAS BLENDED WITH THE 00Z ECMWF/CMC TO
REDUCE THE INPUT FROM THE 06Z GFS.
..WEATHER/HAZARDS HIGHLIGHTS
A MONSOONAL CONVECTIVE PATTERN WILL LINGER OVER THE SOUTHWEST/FOUR
CORNERS STATES THROUGH FRIDAY WITH MOIST SOUTHERLY FLOW WEST OF A
SLOW TO DISLODGE UPPER RIDGE AXIS CENTERED OVER THE SOUTHERN PLAINS.
THE WPC DAY 4/5 EXCESSIVE RAINFALL OUTLOOKS FOR THURSDAY/FRIDAY
HAVE BEEN UPDATED TO DEPICT MARGINAL RISKS FOR UNITED PORTIONS OF
THE FOUR CORNERS STATES. LOCAL STORMS WITH EMBEDDED HEAVY RAIN
COULD CAUSE FLASH FLOODING, PARTICULARLY IN VULNERABLE AREAS.
UPPER TROUGH AMPLIFICATION PROXIMITY ALONG THE WEST COAST PORTENDS
A COOLER AND WETTER PATTERN FOR THE NORTHWEST AND VICINITY THROUGH
LATER THIS WEEK. RAINS AND SPOTTY HIGH ELEVATION MOUNTAIN SNOWS
MAY WORK INLAND ACROSS THE NORTH-CENTRAL INTERMOUNTAIN WEST/ROCKIES
THIS WEEKEND INTO NEXT WEEK DEPENDENT ON THE UNCERTAIN TRACK/TIMING
OF SUPPORTING UPPER TROUGH/LOW EJECTION. RAINS/CONVECTION MAY ALSO
CONSOLIDATE DOWNSTREAM OVER THE NORTH-CENTRAL U.S. GIVEN POSSIBLE
MODERATE CYCLOGENESIS/FRONTOGENESIS FOR FOCUS IN THIS SCENARIO.
UPPER RIDGING FOCUS OVER THE SOUTH-CENTRAL U.S. WILL SUPPORT 5-15
DEGREE ABOVE NORMAL TEMPERATURES INTO THIS WEEKEND. HIGHS WELL
INTO THE 100S IN MUCH OF TEXAS IN PARTICULAR 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 INDICATE MAJOR TO
EXTREME IMPACTS FROM THIS HEAT THROUGH SUNDAY. THIS WILL BE IN
CONTRAST TO COOLING CONDITIONS INTO THE WEST/NORTHWEST AND OVER THE
EASTERN U.S. WHERE SOME RECORD COOL OVERNIGHT TEMPERATURE VALUES
ARE POSSIBLE.
JACKSON
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page