484
FXUS02 KWBC 101905
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 PM EDT MON JUL 10 2023
VALID 12Z THU JUL 13 2023 - 12Z MON JUL 17 2023
...HAZARDOUS TO EXTREME HEAT WILL BUILD ACROSS MUCH OF THE
SOUTHERN U.S. AND INTO THE WEST COAST STATES THROUGH THIS WEEK AND
BEYOND...
...HEAVY RAIN CONCERNS LIKELY TO FOCUS OVER PARTS OF THE MIDWEST
AND MID-MISSISSIPPI VALLEY...
..OVERVIEW
THE UPPER LEVEL PATTERN OVER THE CONUS LATE THIS WEEK AND INTO THE
WEEKEND MAY TREND MORE AMPLIFIED WITH TIME AS TROUGHING IS
MAINTAINED ACROSS THE EASTERN U.S., AND UPPER LEVEL RIDGING BUILDS
INTO THE WEST. THE EASTERN TROUGH WILL BE ANCHORED BY A DEEP UPPER
LOW NEAR HUDSON BAY WITH MULTIPLE WAVES OF ENERGY ROTATING THROUGH
THE BASE DRIVING ROUNDS OF SHOWERS AND STORMS ACROSS THE MIDWEST
AND INTO THE NORTHEAST. HAZARDOUS TO EXTREME HEAT WILL BE ONGOING
AS THE PERIOD BEGINS THURSDAY ACROSS MUCH OF THE SOUTHERN TIER OF
THE U.S. AND BACK INTO THE SOUTHWEST AND CALIFORNIA THROUGH THE
WEEKEND AND WELL INTO NEXT WEEK, AS PER THE LATEST INFORMATION
FROM THE CLIMATE PREDICTION CENTER. THERE IS INCREASING CONFIDENCE
THIS COULD BE A LONG DURATION AND POSSIBLY INTENSE HEAT WAVE FOR
PORTIONS OF THE WEST AND SOUTHERN U.S..
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THE LATEST GUIDANCE IS IN REASONABLE AGREEMENT REGARDING THE
OVERALL SYNOPTIC PATTERN ACROSS THE CONUS DURING THE MEDIUM RANGE.
A RELATIVELY STATIONARY PATTERN IS DEPICTED BY ALL OF THE GUIDANCE
WITH THE SMALL DIFFERENCES IN THE MAGNITUDE AND TIMING OF THE
SHORTWAVE IMPULSES PROPAGATING THROUGH THE PLAINS AND MIDWEST
LATER THIS WEEK AND INTO THE WEEKEND. THE 00Z ECMWF DIVERGES FROM
THE REST OF THE MODELS WHEN IT FURTHER AMPLIFIES THE WESTERN U.S.
RIDGE (500MB HEIGHTS) THIS WEEKEND. A GENERAL MODEL BLEND
CONSISTING OF THE DETERMINISTIC MODELS (00Z EC/CMC/UKMET AND 06Z
GFS) WERE PRIMARILY USED THROUGH DAY 4. THE 06Z GEFS AND 00Z ECE
WERE INTRODUCED ON DAY 5 AND CONTINUED THROUGH THE END OF THE
PERIOD. THE 00Z EC IS PHASED OUT OF THE BLEND ON DAY 6 DUE TO ITS
OUTLIER SOLUTION WITH RESPECT TO THE AFOREMENTIONED WESTERN RIDGE.
..WEATHER/HAZARDS HIGHLIGHTS
A FRONTAL BOUNDARY SETTLING FROM THE CENTRAL PLAINS INTO THE
MIDWEST/OHIO VALLEY SHOULD PROVIDE THE BEST FOCUS FOR DAILY ROUNDS
OF SHOWERS AND STORMS THURSDAY AND FRIDAY. GIVEN AVAILABLE
MOISTURE AND INSTABILITY, HEAVY RAINFALL SEEMS A GOOD BET FOR
PORTIONS OF THE MID-MISSISSIPPI VALLEY INTO THE MIDWEST, BUT EXACT
LOCATION REMAINS RATHER UNCERTAIN STILL. THE BEST OVERLAP IN THE
CURRENT AVAILABLE GUIDANCE POINTS TO THE SOUTHERN MISSOURI TO
KENTUCKY REGION, WHERE A SLIGHT RISK WAS PLACED ON BOTH THE DAYS 4
AND 5 EXCESSIVE RAINFALL OUTLOOKS. IT'S LIKELY THOUGH THIS WILL
SHIFT AND NEED TO BE ADJUSTED IN FUTURE UPDATES. THE NORTHERN
PORTION OF THIS FRONT WILL MOVE INTO THE NORTHEAST WITH ROUNDS OF
ADDITIONAL RAINFALL, AND GIVEN HOW SUSCEPTIBLE THIS REGION IS, A
SLIGHT RISK WAS ADDED TO THE DAYS 4 AND 5 EROS FOR EASTERN
PORTIONS OF NEW YORK AND INTO NEW ENGLAND. BY NEXT WEEKEND,
RAINFALL SHOULD DRIFT SOUTH WITH THE FRONT MORE INTO PARTS OF THE
SOUTH-CENTRAL PLAINS WITH LINGERING SHOWERS ACROSS THE NORTHEAST.
HAZARDOUS HEAT IS EXPECTED TO EXPAND ACROSS THE SOUTHERN TIER
THROUGH AT LEAST NEXT WEEKEND (AND LIKELY BEYOND PER LATEST CPC
FORECASTS) AS THE UPPER RIDGE STRENGTHENS OVER THE SOUTH AND INTO
PARTS OF THE WEST. MUCH ABOVE NORMAL TEMPERATURES WILL EXPAND FROM
THE SOUTHERN HIGH PLAINS INTO THE SOUTHWEST AND CALIFORNIA, WITH
POTENTIAL FOR NUMEROUS RECORD DAILY DAYTIME HIGHS AND WARM
OVERNIGHT LOWS POSSIBLE. FARTHER EAST, AIR TEMPERATURES SHOULD BE
MORE NEAR NORMAL, BUT THE REAL STORY WILL BE OPPRESSIVE HUMIDITY
LEADING TO HEAT INDICES OF 105-115 FOR A LARGE PORTION THE SOUTH
FROM EASTERN TEXAS INTO THE SOUTHEAST, MID-ATLANTIC AND FLORIDA.
AGAIN, SOME DAILY TEMPERATURE RECORDS ARE POSSIBLE. TEMPERATURES
INTO THE 90S TO NEAR 100 ARE POSSIBLE THURSDAY FARTHER NORTH INTO
THE SOUTH-CENTRAL PLAINS BUT SHOULD COOL OFF BY THE WEEKEND AS
UPPER LEVEL TROUGHING MOVES ACROSS THE REGION. ELSEWHERE, A COLD
FRONT DROPPING SOUTH FROM CANADA SHOULD BRING TEMPERATURES DOWN TO
5-15F BELOW AVERAGE OVER PARTS OF THE NORTHERN AND CENTRAL PLAINS
THROUGH SUNDAY WITH SOME MODERATION EARLY NEXT WEEK AS UPPER
RIDGING TRIES TO BUILD IN.
KEBEDE/SANTORELLI
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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