083
FXUS02 KWBC 080727
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
326 AM EDT THU JUN 08 2023
VALID 12Z SUN JUN 11 2023 - 12Z THU JUN 15 2023
...A MULTI-DAY THUNDERSTORM AND LOCAL HEAVY RAIN THREAT WILL
CONTINUE INTO EARLY NEXT WEEK FROM A VERY SATURATED NORTHERN
ROCKIES THROUGH PORTIONS OF THE GREAT PLAINS...
...HEAVY RAIN/STRONG THUNDERSTORM THREAT FROM THE
MIDWEST/MID-SOUTH TO THE EAST THIS WEEKEND INTO EARLY NEXT WEEK
WITH CLOSED LOW GENESIS...
...TEXAS/LOWER MISSISSIPPI VALLEY EXCESSIVE HEAT THREAT BY NEXT
MIDWEEK MAY LINGER BEYOND DAY 7...
..OVERVIEW
THE BLOCKY FLOW PATTERN LOOKS TO PERSIST THROUGH AT LEAST THIS
WEEKEND WITH AN ANOMALOUSLY STRONG UPPER RIDGE/HIGH SANDWICHED
BETWEEN MEAN TROUGHING/CLOSED LOWS OVER THE SOUTHWEST AND THE
NORTHEAST. THIS PATTERN CONTINUES TO SUPPORT DIURNAL SHOWERS AND
STORMS, SOME LOCALLY HEAVY, FROM THE SOUTHERN PLAINS THROUGH THE
NORTHERN ROCKIES AND PARTS OF THE GREAT BASIN. THE NEXT WAVE
ROUNDING THE MID-CONTINENTAL RIDGE CROSSES ONTARIO AND APPROACHES
THE NORTHEAST THIS WEEKEND, WITH A LIKELY CLOSED OFF UPPER LOW
OVER THE UPPER GREAT LAKES BY SUNDAY. THIS WOULD PROMPT AN
ADDITIONAL AND LOCALLY ENHANCED PRECIPITATION FOCUS INTO EARLY
NEXT WEEK OUT ACROSS THE EAST-CENTRAL U.S. AND THEN THE EASTERN
SEABOARD. THE PATTERN SHOULD FINALLY BECOME MORE PROGRESSIVE EARLY
NEXT WEEK AND EXCESSIVE HEAT LOOKS TO BUILD ACROSS TEXAS AND INTO
THE LOWER MISSISSIPPI VALLEY.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THERE REMAINS GOOD AGREEMENT ON THE WEATHER PATTERN ACROSS THE
CONUS THE FIRST HALF OF THE PERIOD, BOLSTERING FORECAST
CONFIDENCE. A GENERAL MODEL BLEND WAS USED FOR SUNDAY-TUESDAY.
THERE'S ALSO GOOD SYNOPTIC AGREEMENT BEYOND TUESDAY THAT THE
PATTERN SHOULD FINALLY BREAK DOWN AND BECOME MORE PROGRESSIVE,
THOUGH STILL WITH PLENTY OF DIFFERENCES IN TIMING AND DETAILS OF
SYSTEMS. THE GREAT LAKES CLOSED LOW IS SHOWING BETTER AGREEMENT,
BUT THE GFS REMAINS ON THE FASTER SIDE TO MOVE THE SYSTEM OF THE
NORTHEAST NEXT WEEK. THE GFS IS ALSO CONSIDERABLY FASTER WITH THE
UPPER LOW OVER CALIFORNIA AS IT EJECTS INTO THE ROCKIES/PLAINS
LATE PERIOD. PREFER A BLEND CLOSER TO THE SLOWER AND MORE
AMPLIFIED ECMWF WHICH ALSO FITS WELL WITH THE ENSEMBLE MEANS AND
WPC CONTINUITY. AS SUCH, THE BLEND FOR DAYS 6 AND 7 INCLUDED THE
ECMWF WITH THE ENSEMBLE MEANS.
..WEATHER/HAZARDS HIGHLIGHTS
A DAILY RISK FOR HEAVY SHOWERS AND STRONG TO SEVERE THUNDERSTORMS
FROM THE SOUTHERN PLAINS THROUGH THE NORTHERN ROCKIES AND WESTWARD
INTO THE GREAT BASIN IS EXPECTED TO BE SLOW TO DISLODGE OVER ABOUT
THE NEXT WEEK AS TROPICAL PACIFIC MOISTURE REMAINS FUNNELED
NORTHWARD BETWEEN A STRONG CENTRAL U.S. RIDGE AND AN UPPER
LOW/TROUGH PARKED OVER CALIFORNIA/THE SOUTHWEST. A WEAKENING
BOUNDARY THROUGH THE REGION SHOULD ALSO HELP TO ENHANCE RAINFALL
TOTALS, WITH PARTICULAR CONCERNS OVER AREAS THAT HAVE BEEN VERY
WET AS OF LATE (NORTHERN AND CENTRAL ROCKIES/WESTERN GREAT
PLAINS). MAINTAINED A "SLIGHT RISK" ON THE DAY 4 EXCESSIVE
RAINFALL OUTLOOK IN EASTERN COLORADO AND FAR SOUTHEAST WYOMING
WITH A BROAD MARGINAL RISK ELSEWHERE DAY 4 AND ON DAY 5.
FARTHER INTO THE CENTRAL U.S. AND OHIO VALLEY, THE CLOSED LOW OVER
THE GREAT LAKES AND ASSOCIATED SURFACE COLD FRONT SHOULD HELP
FOCUS ANOMALOUS MOISTURE AND PLENTY OF INSTABILITY TO PRODUCE AT
LEAST LOCALLY HEAVY RAINFALL FROM THE UPPER GREAT LAKES/MIDWEST,
SOUTHWARD INTO THE TENNESSEE VALLEY AND PARTS OF THE SOUTHEAST ON
SUNDAY. AFTER COORDINATION WITH THE AFFECTED WFOS, AND CONSIDERING
LINGERING MODEL UNCERTAINTY AND ALSO HOW DRY THIS REGION HAS BEEN
LATELY, OPTED TO REMOVE THE SLIGHT RISK ON THE DAY 4 ERO ACROSS
PARTS OF THE TENNESSEE VALLEY. IT IS POSSIBLE A SLIGHT RISK WILL
NEED TO BE REINTRODUCED IN FUTURE UPDATES IF MODEL SUPPORT
INCREASES. THE FRONT WILL PUSH INTO THE EASTERN U.S. BY MONDAY
WITH NUMEROUS SHOWERS AND STORMS TO ACCOMPANY THE FRONT AS IT
MOVES INTO THE EASTERN U.S.. ANTECEDENT DRY CONDITIONS AND THE
PROGRESSIVE NATURE OF THE FRONT PRECLUDE ANYTHING MORE THAN A
BROAD MARGINAL RISK ON THE DAY 5 ERO AT THIS TIME. ELSEWHERE,
EJECTING ENERGIES OUT OF THE SOUTHWEST ALSO LOOK TO FAVOR
ADDITIONAL ROUNDS OF RAINFALL AND CONVECTION AGAIN AROUND MID-WEEK
NEXT WEEK FOR PARTS OF THE SOUTH-CENTRAL PLAINS ALONG A WARM FRONT.
TEMPERATURES OVER THE NORTHERN TIER AND BACK INTO THE PACIFIC
NORTHWEST WILL CONTINUE TO BE WARM, WITH ANOMALIES 10-15 DEGREES
ABOVE NORMAL IN SOME PLACES, THROUGH ABOUT TUESDAY BEFORE THE
UPPER RIDGE FINALLY SUPPRESSES AND PUSHES EAST. UNDERNEATH
POSSIBLE CLOSED LOW DEVELOPMENT OVER THE GREAT LAKES/MIDWEST AND
BACK INTO THE SOUTHWEST/CALIFORNIA, TEMPERATURES SHOULD TREND
MODERATELY COOLER THAN NORMAL. THERE CONTINUES TO BE A SIGNAL FOR
A BUILDING EXCESSIVE HEAT THREAT FOR TEXAS INTO THE LOWER
MISSISSIPPI VALLEY AS UPPER RIDGING BECOMES BETTER ESTABLISHED
OVER THE REGION. DAYTIME HIGHS 10-15F ABOVE NORMAL, WITH HEAT
INDICES POSSIBLY IN EXCESS OF 110F, MAINLY FOR CENTRAL TO LOWER
TEXAS. AS PER THE LATEST INFORMATION FROM THE CLIMATE PREDICTION
CENTER, THIS THREAT APPEARS LIKELY TO LINGER BEYOND DAY 7/THURSDAY.
SANTORELLI
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, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
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