940
FXUS02 KWBC 090700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 AM EDT FRI JUN 9 2023
VALID 12Z MON JUN 12 2023 - 12Z FRI JUN 16 2023
...HEAVY RAIN AND STRONG STORMS FOR PORTIONS OF THE HIGH PLAINS
AND INTO THE MID-SOUTH, AND HEAT CONTINUES TO BUILD FROM TEXAS TO
ALABAMA...
..SYNOPTIC OVERVIEW
THE UPPER LOW THAT HAS BEEN NEARLY ANCHORED IN PLACE ACROSS NEW
ENGLAND WILL SLOWLY BE LIFTING AWAY ACROSS THE CANADIAN MARITIMES
BY EARLY MONDAY, WITH ANOTHER WELL-DEFINED LOW DEVELOPING ACROSS
THE GREAT LAKES AS A SHORTWAVE DROPS SOUTH FROM THE HUDSON BAY
REGION. THIS WILL SPUR SURFACE CYCLOGENESIS ACROSS THE OHIO
VALLEY EARLY IN THE WEEK WITH A TRAILING COLD FRONT REACHING THE
EAST COAST AROUND TUESDAY, AND THIS WILL LIKELY BRING WIDESPREAD
SHOWERS AND STORMS FROM THE MID-ATLANTIC TO NEW ENGLAND. A SECOND
CLOSED UPPER LOW IS EXPECTED ACROSS THE SOUTHWESTERN U.S. EARLY IN
THE WEEK AND THIS SHOULD REACH THE CENTRAL/SOUTHERN PLAINS BY
MIDWEEK THAT WILL LIKELY SUPPORT A SURFACE LOW ALONG THE FRONT,
AND THIS WILL ALSO TEND TO INCREASE THE PROSPECTS FOR WIDESPREAD
SHOWERS AND STORMS FROM NORTHERN TEXAS/OKLAHOMA EASTWARD ACROSS
THE MID-SOUTH AND THE SOUTHERN APPALACHIANS WEDNESDAY THROUGH
FRIDAY.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE HAS CONSOLIDATED WELL WITH THE
PLACEMENT OF THE UPPER LOWS ACROSS THE SOUTHWEST AND GREAT LAKES
REGION AND THE CORRESPONDING SURFACE FEATURES FOR THE BEGINNING OF
THE WEEK. THE PAST COUPLE OF GFS RUNS HAVE BEEN SLIGHTLY MORE
AMPLIFIED WITH SHORTWAVE ENERGY IN THE SOUTHERN STREAM ACROSS THE
GULF COAST REGION FOR MID-WEEK, AND THE GFS IS A LITTLE SLOWER IN
LIFTING OUT THE LOW ACROSS THE NORTHEAST. THE GUIDANCE HAS ALSO
COME INTO BETTER AGREEMENT WITH A BUILDING TROUGH ACROSS THE
NORTHERN ROCKIES AND NORTHWEST LATE IN THE WEEK, WITH THE 00Z CMC
NOW MORE IN LINE WITH THE CONSENSUS COMPARED TO ITS 12Z RUN. THE
WPC FORECAST INCORPORATED A NEARLY DETERMINISTIC MODEL BLEND
THROUGH EARLY WEDNESDAY, FOLLOWED BY SLIGHTLY LESS WEIGHTING OF
THE GFS AND MORE OF THE ENSEMBLE MEANS GOING INTO THURSDAY AND
FRIDAY.
..WEATHER/HAZARDS HIGHLIGHTS
A DAILY RISK FOR HEAVY SHOWERS AND STRONG TO SEVERE THUNDERSTORMS
FROM THE SOUTHERN PLAINS TO THE NORTHERN ROCKIES AND WESTWARD INTO
THE GREAT BASIN IS EXPECTED TO BE SLOW TO DISLODGE THROUGH ABOUT
MID-WEEK, AS TROPICAL PACIFIC MOISTURE ADVECTS NORTHWARD BETWEEN A
STRONG CENTRAL U.S. UPPER RIDGE AND AN UPPER LOW/TROUGH PARKED
OVER CALIFORNIA/SOUTHWEST EARLY IN THE WEEK. A WEAKENING BOUNDARY
THROUGH THE REGION SHOULD ALSO HELP TO ENHANCE RAINFALL TOTALS,
WITH PARTICULAR CONCERNS OVER AREAS THAT HAVE SEEN WELL ABOVE
AVERAGE RAINFALL OVER THE PAST TWO WEEKS (NORTHERN AND CENTRAL
ROCKIES/WESTERN GREAT PLAINS). A SLIGHT RISK AREA HAS BEEN
INTRODUCED ON THE DAY 4 EXCESSIVE RAINFALL OUTLOOK ACROSS
NORTHEASTERN COLORADO AND SMALL PORTIONS OF NEIGHBORING STATES,
WITH A BROAD MARGINAL RISK EXTENDING FROM THE INTERMOUNTAIN WEST
TO THE CENTRAL PLAINS.
THE CLOSED LOW OVER THE GREAT LAKES AND TRAILING SURFACE COLD
FRONT WILL ADVECT COPIOUS MOISTURE NORTHWARD ACROSS THE
MID-ATLANTIC AND NORTHEAST, AND IN COMBINATION WITH AMPLE
INSTABILITY WILL LIKELY PRODUCE STORMS WITH LOCALLY HEAVY
RAINFALL, WITH A MARGINAL RISK OF EXCESSIVE RAINFALL IN EFFECT FOR
MONDAY-MONDAY NIGHT. ANTECEDENT DRY CONDITIONS AND THE
PROGRESSIVE NATURE OF THE FRONT PRECLUDE ANYTHING MORE THAN A
BROAD MARGINAL RISK AT THIS TIME. ELSEWHERE, EJECTING SHORTWAVES
FROM THE SOUTHWEST ALSO APPEAR TO FAVOR ADDITIONAL ROUNDS OF HEAVY
RAINFALL AND CONVECTION AGAIN AROUND MID-WEEK FOR PARTS OF THE
SOUTH-CENTRAL PLAINS TO THE MID-SOUTH WITH COPIOUS GULF MOISTURE
INTERSECTING A QUASI-STATIONARY FRONTAL BOUNDARY.
THERE WILL BE TWO AREAS OF THE U.S. THAT WILL LIKELY HAVE ABOVE
NORMAL TEMPERATURES NEXT WEEK, WITH THE FIRST BEING ACROSS THE
DAKOTAS AND INTO MINNESOTA, WISCONSIN, AND IOWA WHERE READINGS ARE
EXPECTED TO BE 5-15 DEGREES ABOVE MID-JUNE AVERAGES. THE SECOND
AND MORE IMPACTFUL AREA IS ACROSS TEXAS INTO THE CENTRAL GULF
COAST REGION AS UPPER RIDGING BECOMES BETTER ESTABLISHED OVER THE
REGION TO THE SOUTH OF A FRONTAL BOUNDARY. WIDESPREAD MID-UPPER
90S ARE EXPECTED, AND 100S ACROSS THE NORMALLY WARMER LOCATIONS
ACROSS SOUTHERN TEXAS, ALONG WITH INCREASING HUMIDITY LEVELS.
SOME DAILY RECORD HIGHS ARE POSSIBLE, MAINLY MID-LATE NEXT WEEK.
THIS HEAT WAVE WILL LIKELY HAVE SOME STAYING POWER BEYOND NEXT
FRIDAY. ELSEWHERE, UNDERNEATH CLOSED UPPER LOW DEVELOPMENT OVER
THE GREAT LAKES/MIDWEST AND ALSO OVER THE SOUTHWEST/CALIFORNIA,
TEMPERATURES SHOULD FEEL MORE LIKE THE MONTH OF MAY.
HAMRICK
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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