281
FXUS02 KWBC 070704
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 AM EDT WED JUN 07 2023
VALID 12Z SAT JUN 10 2023 - 12Z WED JUN 14 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...
..OVERVIEW
A QUITE BLOCKY FLOW PATTERN LOOKS TO PERSIST THROUGH AT LEAST
EARLY NEXT WEEK AS AN ANOMALOUSLY STRONG UPPER RIDGE/HIGH REMAINS
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 GROWING CONSENSUS ON
CLOSING OFF A LOW OVER THE UPPER GREAT LAKES AROUND MONDAY-TUESDAY
NEXT WEEK. THIS WOULD PROMPT AN ADDITIONAL AND LOCALLY ENHANCED
PRECIPITATION FOCUS BY LATER WEEKEND INTO EARLY NEXT WEEK OUT
ACROSS THE EAST-CENTRAL U.S. AND THEN THE EASTERN SEABOARD.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THERE REMAINS FAIRLY GOOD AGREEMENT ON THE OVERALL SYNOPTIC SCALE
PATTERN ACROSS THE CONUS INTO EARLY NEXT WEEK. THE FIRST HALF OF
THE PERIOD WAS BASED ON A BLEND OF THE LATEST DETERMINISTIC
SOLUTIONS (AND THE NATIONAL BLEND OF MODELS FOR QPF). EVEN INTO
DAYS 6 AND 7 (TUESDAY AND WEDNESDAY) THOUGH, MODELS SEEM TO BE
TRENDING TOWARDS A FAIRLY STRONG CLOSED LOW OVER THE GREAT LAKES,
WITH SOME WEAKENING/OPENING UP AS IT PUSHES INTO THE NORTHEAST.
THE GFS SOLUTIONS REMAIN ON THE MORE PROGRESSIVE SIDE WHICH THE
ECMWF/CMC A LITTLE SLOWER, WHICH HAS MORE SUPPORT FROM THE
ENSEMBLES AS WELL. MEANWHILE, OUT WEST, THE MODELS AGREE A CLOSED
LOW OVER CALIFORNIA/THE SOUTHWEST SHOULD OPEN UP AND SHIFT EAST
AND POSSIBLY FINALLY BREAK DOWN THE BLOCKY PATTERN. PLENTY OF
UNCERTAINTY AND TRENDS LEFT TO MONITOR THOUGH. FOR DAYS 6 AND 7,
THE WPC FORECAST LEANED TOWARDS THE ENSEMBLE MEANS ALONG WITH THE
DETERMINISTIC ECMWF AND CMC FOR SOME ADDED DETAILS. THIS MAINTAINS
GOOD CONTINUITY WITH THE PREVIOUS WPC PROGS AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
A DAILY RISK FOR HEAVY SHOWERS AND STRONG 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 FRONTAL BOUNDARY DROPPING SOUTH
AND EASTWARD THROUGH THE REGION SHOULD ALSO HELP TO ENHANCE
RAINFALL TOTALS THIS WEEKEND, WITH PARTICULAR CONCERNS OVER AREAS
THAT HAVE BEEN VERY WET AS OF LATE (NORTHERN AND CENTRAL
ROCKIES/WESTERN GREAT PLAINS). THERE WAS ENOUGH MODEL SUPPORT TO
ADD A SLIGHT RISK ON THE DAY 4 EXCESSIVE RAINFALL OUTLOOK FROM
CENTRAL/EASTERN MONTANA INTO WESTERN NEBRASKA ESPECIALLY GIVEN
HIGH STREAM FLOWS IN THAT REGION. THE DYNAMICS SUPPORT AT LEAST
LOCALLY HEAVY CONVECTION AND POSSIBLE COMPLEXES FARTHER SOUTH AND
EAST ALONG THE BOUNDARY INTO THE SOUTH-CENTRAL PLAINS/MISSISSIPPI
VALLEY BUT THERE IS STILL ENOUGH MODEL UNCERTAINTY OVER THIS
REGION WHICH HAS ALSO BEEN MUCH DRIER TO PRECLUDE EXTENDING THE
SLIGHT RISK THAT FAR EAST ON DAY 4. IT COULD BE NEEDED IN FUTURE
UPDATES THOUGH AS MODELS BEGIN TO RESOLVE THE DETAILS MORE. FOR
DAY 5, A SLIGHT RISK IS DEPICTED IN EASTERN COLORADO AND FAR
SOUTHEAST WYOMING MAINLY GIVEN THE ANTECEDENT WETNESS AND
FAVORABLE CONDITIONS.
FARTHER INTO THE CENTRAL U.S. AND THE OHIO VALLEY, STRONG
THUNDERSTORMS SHOULD FOCUS ALONG THE FAIRLY PROGRESSIVE FRONTAL
BOUNDARY AND A MARGINAL RISK REMAINS EXPANDED INTO THIS REGION FOR
DAYS 4 AND 5 AS MODELS INDICATE THE POTENTIAL FOR AT LEAST LOCALLY
HEAVY RAINFALL. THE GREAT LAKES CLOSED UPPER TROUGH/LOW
DEVELOPMENT AND ASSOCIATED AND WRAPPING SURFACE LOW AND FRONTAL
CHARACTERISTICS TRAILING OVER THE APPALACHIANS/EAST/SOUTHEAST INTO
EARLY NEXT WEEK MAY THEN SET THE STAGE FOR DEVELOPMENT OF A
PATTERN FAVORING ADDITIONAL WIDESPREAD THREATS FOR HEAVY
RAIN/THUNDERSTORMS TO MONITOR. EJECTING ENERGIES OUT OF THE
SOUTHWEST ALSO LOOKS TO FAVOR ADDITIONAL ROUNDS OF RAINFALL AND
CONVECTION AGAIN AROUND MID-WEEK NEXT WEEK FOR PARTS OF THE
SOUTH-CENTRAL PLAINS.
TEMPERATURES OVER THE NORTHERN TIER AND BACK INTO THE PACIFIC
NORTHWEST SHOULD MODERATE SOME THIS WEEKEND, BUT MAY CREEP BACK UP
AGAIN EARLY NEXT WEEK WITH ANOMALIES GENERALLY +10-15F POSSIBLE.
UNDERNEATH POSSIBLE CLOSED LOW DEVELOPMENT OVER THE GREAT
LAKES/MIDWEST AND BACK INTO THE SOUTHWEST/CALIFORNIA, TEMPERATURES
SHOULD TREND COOLER THAN NORMAL. UPPER RIDGING MOVING INTO PARTS
OF THE SOUTHERN PLAINS EARLY TO MIDDLE OF NEXT WEEK SHOULD ALLOW
FOR WARMER THAN AVERAGE VALUES THERE AS WELL.
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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