265
FXUS02 KWBC 050642
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 AM EDT MON JUN 05 2023
VALID 12Z THU JUN 08 2023 - 12Z MON JUN 12 2023
...A BROAD MULTI-DAY THUNDERSTORM AND LOCAL HEAVY RAIN THREAT WILL
CONTINUE OVER THE NEXT WEEK FROM THE NORTHERN ROCKIES TO THE GREAT
PLAINS...
..OVERVIEW
THE UPPER LEVEL PATTERN DURING THE MEDIUM RANGE PERIOD WILL REMAIN
VERY AMPLIFIED AND BLOCKY OVER THE CONUS AS AN ANOMALOUSLY STRONG
UPPER RIDGE IS SANDWICHED BETWEEN MEAN TROUGHING ALONG THE WEST
COAST AND ALSO IN THE NORTHEAST. THIS PATTERN SUPPORTS DAILY
SHOWERS AND STORMS, SOME LOCALLY HEAVY, FROM THE SOUTHERN PLAINS
INTO THE NORTHERN ROCKIES AND PARTS OF THE GREAT BASIN, AN AREA
WHICH HAS BEEN QUITE WET AS OF LATE. THERE ARE SOME INDICATIONS
THE PATTERN MAY FINALLY EITHER BREAK DOWN OR SHIFT EASTWARD AROUND
NEXT WEEKEND BUT THERE IS A LOT OF UNCERTAINTY IN THE SPECIFICS.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
A GENERAL MODEL BLEND OF THE DETERMINISTIC SOLUTIONS WORKED WELL
FOR DAYS 3-5 AMIDST GOOD MODEL AGREEMENT. BY DAYS 6 AND 7, THERE
IS GROWING SPREAD REGARDING A SHORTWAVE DROPPING IN TOWARDS THE
UPPER GREAT LAKES. THE ECMWF CONTINUES TO BE WEAKER/MORE
PROGRESSIVE WITH THIS FEATURE INTO THE NORTHEAST NEXT MONDAY,
LIKELY DUE TO BEING MORE AGGRESSIVE TO BREAK DOWN THE CENTRAL U.S.
RIDGE. THE BETTER CONSENSUS (INCLUDING THE GFS AND CMC) MAINTAIN
THE OMEGA BLOCK OVER THE CONUS ALLOWING THIS TROUGHING TO DIG
DEEPER INTO THE MIDWEST. OUT WEST, AN INITIAL UPPER LOW OVER
CALIFORNIA ON THURSDAY SHOULD WEAKEN AND LIFT NORTH AS A SECOND
PIECE OF ENERGY CUTS OFF FROM EASTERN PACIFIC TROUGHING TO CLOSE
OFF A DEEP LOW OVER SOUTHERN CALIFORNIA AGAIN BY NEXT WEEKEND.
MODELS SEEM TO BE TRENDING TOWARDS A RATHER STRONG LOW, BUT THERE
REMAINS SOME UNCERTAINTY IN THE DETAILS OF ITS EVOLUTION. THE WPC
BLEND FAVORED THE BETTER AGREEABLE ENSEMBLE MEANS LATE PERIOD
GIVEN THIS ISSUES DESCRIBED ABOVE.
..WEATHER/HAZARDS HIGHLIGHTS
A DAILY DIURNAL RISK FOR HEAVY SHOWERS AND THUNDERSTORMS WILL BE
MAINTAINED THROUGH MUCH OF THE PERIOD FROM THE SOUTHERN PLAINS TO
THE NORTHERN ROCKIES AND WESTWARD INTO THE GREAT BASIN AS TROPICAL
PACIFIC MOISTURE IS FUNNELED NORTHWARD IN BETWEEN A STRONG CENTRAL
U.S. RIDGE AND THE UPPER LOW PARKED OVER CALIFORNIA. THE DAYS 4
AND 5 EXCESSIVE RAINFALL OUTLOOKS CONTINUE TO DEPICT A LARGE
MARGINAL RISK ACROSS THIS ENTIRE REGION. AN EMBEDDED SLIGHT WAS
PLACED ACROSS PARTS OF MONTANA AS ANOMALOUS MOISTURE FOCUSES ALONG
A FRONTAL BOUNDARY OVER AN AREA THAT HAS BEEN VERY WET LATELY.
ADDITIONAL EMBEDDED SLIGHT RISKS ARE ALSO POSSIBLE WITHIN THE
LARGER MARGINAL RISK AREA, ESPECIALLY IF HEAVY RAINFALL FALLS OVER
ANTECEDENT WET AREAS.
ELSEWHERE, A FRONT MOVING SOUTHWARD THROUGH THE UPPER MIDWEST AND
OHIO VALLEY LATER THIS WEEK INTO THE WEEKEND SHOULD FOCUS SHOWERS
AND THUNDERSTORMS ALONG THE BOUNDARY. A LEADING COLD FRONT
SETTLING OVER THE SOUTHEAST SHOULD BE A SECONDARY FOCUS FOR
SCATTERED CONVECTION, WITH POSSIBLY MORE WIDESPREAD/HEAVY SHOWERS
ACROSS SOUTHERN FLORIDA LATER THIS WEEK ALONG A WEAKENING FRONT.
ANOMALOUS RIDGING WILL GENERALLY MAINTAIN ABOVE NORMAL
TEMPERATURES MOST DAYS FROM THE UPPER MIDWEST/NORTHERN PLAINS INTO
THE NORTHWEST. THE WARMEST DAY LOOKS TO BE THURSDAY, WHERE DAYTIME
HIGHS COULD BE 10 TO 20 DEGREES ABOVE NORMAL, ESPECIALLY FOR PARTS
OF CENTRAL AND WESTERN WASHINGTON. TEMPERATURES SHOULD MODERATE
SOME ACROSS THE NORTHERN TIER STATES INTO NEXT WEEKEND. EXPECT
NEAR TO BELOW NORMAL TEMPERATURES OVER THE NORTHEAST AND AT TIMES
INTO THE MID-ATLANTIC BENEATH UPPER TROUGHING, MAINLY EARLY IN THE
PERIOD. CLOUDS AND PERIODS OF RAINFALL SHOULD KEEP HIGHS 5-10F OR
SO BELOW NORMAL OVER THE SOUTHERN HALF OF THE ROCKIES/HIGH PLAINS
FOR MOST OF THE PERIOD AND THE SECOND UPPER LOW REACHING SOUTHERN
CALIFORNIA NEXT WEEKEND WILL BRING A REINFORCING SHOT OF MUCH
COOLER TEMPERATURES 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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