744
FXUS02 KWBC 281905
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
305 PM EDT FRI JUN 28 2024
VALID 12Z MON JUL 01 2024 - 12Z FRI JUL 05 2024
...HAZARDOUS HEAT FROM THE SOUTH AND VICINITY NEXT WEEK TO
PORTIONS OF THE EAST/SOUTHEAST AND CALIFORNIA INTO THE FOURTH...
..OVERVIEW
AN ACTIVE SUMMER WEATHER PATTERN WILL CONTINUE TO FEATURE A
PATTERN OF ENERGETIC AND PROGRESSIVE NORTHERN STREAM SHORTWAVES
THROUGH THE NORTHERN STATES AS A STRONG RIDGE SHIFTS SLOWLY OVER
THE SOUTH, EVENTUALLY BUILDING BACK INTO THE EAST AND WEST COASTS.
A THREAT FOR HEAVY RAINS WILL BE ACROSS THE UPPER MIDWEST MONDAY-
TUESDAY, WITH FOCUS SLOWLY WORKING OVER THE MID-MISSISSIPPI/OHIO
VALLEYS AND VICINITY THROUGH THE HOLIDAY.IT SHOULD ALSO REMAIN A
WET PATTERN ACROSS THE SOUTHWEST WITH A CONTINUOUS AND HIGHLY
ANOMALOUS MOISTURE FEED AROUND THE WESTERN PERIPHERY OF THE RIDGE.
HAZARDOUS HEAT THREATS WILL FOCUS ACROSS MUCH OF THE SOUTHERN
PLAINS TO SOUTHEAST/EAST OVER THE PERIOD, BUILDING INTO PARTS OF
THE SOUTHWEST AND INTERIOR CALIFORNIA BY MID TO LATER NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE FORECAST SPREAD CONTINUES A TREND OF BEING LOWER THAN
NORMAL THROUGH MEDIUM RANGE TIME SCALES IN A PATTERN WITH ABOVE
AVERAGE PREDICTABILITY OVERALL. THE WPC PRODUCT SUITE WAS MAINLY
DERIVED FOR THE MONDAY-WEDNESDAY TIMEFRAME FROM A BLEND OF THE 06
UTC GFS AND 00 UTC ECMWF/UKMET/CANADIAN ALONG WITH THE GENERALLY
COMPATIBLE 13 UTC NATIONAL BLEND OF MODELS (NBM) AND WPC
CONTINUITY. APPLIED MOST BLEND WEIGHTING TO THE ECMWF/UKMET THAT
DEPICT A STRONGER AND MORE RESILIENT SOUTHERN UPPER RIDGE THAT MAY
PROVE SLOW TO DISSIPATE. OPTED TO SWITCH THE FAVORED BLEND TO BEST
CLUSTERED GUIDANCE FROM THE ECMWF AND GEFS/ECMWF ENSEMBLE MEANS
ALONG WITH THE NBM FOR LATER NEXT WEEK AMID SLOWLY GROWING, BUT
MANAGEABLE VARIANCES.
..WEATHER/HAZARDS HIGHLIGHTS
IT GENERALLY REMAINS THE CASE THAT WIDESPREAD SHOWERS AND STORMS
ARE EXPECTED TO BE ONGOING ACROSS THE UPPER MIDWEST ON MONDAY AHEAD
OF A FRONTAL BOUNDARY AND AN UPPER LEVEL IMPULSE MOVING THROUGH
THE REGION. ALTHOUGH THE OVERALL FORECAST RAINFALL TOTALS ARE
CURRENTLY EXPECTED TO BE IN THE 1-2 INCH RANGE, THIS WOULD BE
FALLING ON HIGHLY SATURATED GROUNDS IN MANY CASES, WHICH WOULD BE
AN AGGRAVATING FACTOR WHEN IT COMES TO FLOODING POTENTIAL.
THEREFORE, THE SLIGHT RISK REMAINS VALID FOR THE NEW DAY 4 ERO
ACROSS MUCH OF MINNESOTA AND PORTIONS OF ADJACENT STATES. MARGINAL
AND SLIGHT RISK ERO AREAS ARE PLANNED FOR DAY 5 AS THE SIGNAL FOR A MAIN
AXIS OF HEAVY CONVECTION SHIFTS TO/FROM KANSAS/IOWA THROUGH
WISCONSIN/ILLINOIS INTO THE GREAT LAKES, POSSIBLE SPREADING ACROSS
THE OHIO VALLEY TOWARD THE MID-ATLANTIC OVER THE HOLIDAY PERIOD.
ELSEWHERE, MOISTURE POOLING AHEAD OF THE COLD FRONT APPROACHING THE
SOUTHEAST U.S. COAST MAY LEAD TO SOME REPEATED ROUNDS OF STORMS
WITH HIGH RAINFALL RATES ON MONDAY, WHERE A DAY 4 MARGINAL RISK
AREA IS PLANNED.
MONSOONAL FLOW INTO THE SOUTHWEST STATES WILL CONTINUE THE DAILY
THREAT FOR SHOWERS AND STORMS THROUGH MUCH OF THE PERIOD. MARGINAL
RISKS REMAIN IN PLACE ACROSS PARTS OF ARIZONA, NEW MEXICO, AND
SOUTHERN COLORADO FOR BOTH THE DAY 4 AND 5 EROS, WITH THE
POTENTIAL FOR UPGRADES TO A SLIGHT RISK IN SUBSEQUENT UPDATES
DEPENDING ON SHORT RANGE RAINFALL. THIS PATTERN IS LIKELY TO
PERSIST INTO NEXT WEDNESDAY AS WELL GIVEN THE LINGERING AND
DEEPENED MOISTURE CHANNEL ON THE UPPER RIDGE WESTERN PERIPHERY.
IT WILL CONTINUE TO REMAIN HOT AND HUMID ACROSS THE SOUTHERN U.S.
FOR MUCH OF NEXT WEEK, WITH THE HOTTEST CONDITIONS CENTERED ACROSS
TEXAS AND OKLAHOMA WHERE TRIPLE DIGIT HIGH TEMPERATURES ARE LIKELY.
SOME OF THIS HEAT LIKELY REACHES THE MID-ATLANTIC REGION BY THE
END OF THE WEEK WITH HIGHS IN THE MIDDLE TO UPPER 90S. IT WILL ALSO
BE GETTING HOTTER FOR THE INLAND LOWER ELEVATIONS OF CALIFORNIA AND
INTO THE ARIZONA DESERTS WITH WIDESPREAD 100-110 DEGREE READINGS
LIKELY, AND LOCALLY HIGHER FOR THE NORMALLY WARMER LOCATIONS.
HAMRICK/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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page