470
FXUS02 KWBC 030633
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
232 AM EDT SAT JUN 03 2023
VALID 12Z TUE JUN 06 2023 - 12Z SAT JUN 10 2023
...BROAD MULTI-DAY THUNDERSTORM AND LOCAL HEAVY RAIN THREAT FROM
THE NORTHERN ROCKIES TO THE SOUTHERN GREAT PLAINS CONTINUES WELL
INTO NEXT WEEK...
..OVERVIEW
THE UPPER LEVEL PATTERN DURING THE MEDIUM RANGE PERIOD NEXT WEEK
WILL REMAIN BLOCKY AS AN ANOMALOUSLY STRONG UPPER RIDGE IS
SANDWICHED BETWEEN STAGNANT UPPER LOWS IN THE NORTHEAST U.S. AND
OVER CALIFORNIA. THIS PATTERN SUPPORTS DAILY SHOWERS AND STORMS
FROM THE SOUTHERN PLAINS INTO THE NORTHERN ROCKIES AND PARTS OF
THE GREAT BASIN, AN AREA WHICH HAS BEEN QUITE WET AS OF LATE.
PROLONGED ABOVE NORMAL TEMPERATURES ARE ALSO EXPECTED FROM THE
NORTHWEST INTO THE NORTHERN PLAINS AND UPPER MIDWEST/MISSISSIPPI
VALLEY.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THE LATEST SUITE OF GUIDANCE CONTINUES TO CAPTURE THE OVERALL
SYNOPTIC PATTERN REASONABLY WELL AND A GENERAL MODEL BLEND
SUFFICED FOR AT LEAST THE FIRST HALF OF THE PERIOD. THERE ARE SOME
DETAIL DIFFERENCES TO BE WORKED OUT STILL, PARTICULARLY ACROSS THE
NORTHEAST AS PIECES OF ENERGY ACT TO REINFORCE A MEAN UPPER LOW
OVER THE REGION. PREVIOUS RUNS SUPPORTED A SCENARIO WITH A COUPLE
OF CLOSED LOWS, BUT THE LATEST RUNS SEEM TO BE TRENDING TOWARDS
ONE CONSOLIDATED LOW THROUGH MOST OF NEXT WEEK (WITH THE EXCEPTION
OF THE CMC). THERE ARE DIFFERENCES IN HOW FAR SOUTH INTO THE
MID-ATLANTIC/SOUTHEAST THE LOWER HEIGHTS GET TOO. OUT WEST, THE
MAIN DIFFERENCES BEGIN TO ARISE AFTER DAY 5 AS THE GFS CONTINUES
TO BE QUICKEST TO ERODE THE UPPER LOW OVER CALIFORNIA, AND BRINGS
TROUGHING FARTHER INTO THE WESTERN U.S. THAN OTHER SOLUTIONS (EVEN
TRYING TO BREAK DOWN THE CENTRAL U.S. RIDGE BY NEXT WEEKEND). THE
WPC BLEND FOR THE SECOND HALF OF THE PERIOD FAVORS THE ECMWF
(GIVEN THE BETTER RUN-TO-RUN CONSISTENCY) ALONG WITH THE ENSEMBLE
MEANS WHICH HELPS MITIGATE THE DETAIL DIFFERENCES. THIS APPROACH
MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
A DAILY DIURNAL RISK FOR HEAVY SHOWERS AND THUNDERSTORMS WILL BE
MAINTAINED THROUGH 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 AN UPPER LOW PARKED OVER CALIFORNIA. FOR NOW, THE
DAYS 4 AND 5 EXCESSIVE RAINFALL OUTLOOKS CONTINUE TO DEPICT JUST
ONE LARGE MARGINAL RISK AREA FOR THIS REGION, HOWEVER EMBEDDED
SLIGHT RISK AREAS MAY BECOME NECESSARY IF HEAVY RAINS FOCUS OVER
ANTECEDENT WET AREAS. FOR PARTS OF CENTRAL MONTANA, A COLD FRONT
LOOKS TO DROP INTO THE REGION SUPPORTING AN INCREASED RISK FOR
HEAVY RAINFALL AND FLASH FLOODING BY DAYS 6 AND 7 (THIS AREA HAS
BEEN VERY WET AND IS MORE SUSCEPTIBLE ANYWAYS).
ELSEWHERE, A COLD FRONT THROUGH THE GREAT LAKES/UPPER MIDWEST
EARLY IN THE WEEK SHOULD FOCUS SHOWERS AND STORMS AHEAD OF IT
ACROSS THE NORTHERN PLAINS/UPPER MISSISSIPPI VALLEY. WITH DECENT
MOISTURE AND INSTABILITY, A MARGINAL RISK REMAINS ON THE DAY 4
EXCESSIVE RAINFALL OUTLOOK. IN THE NORTHEAST, THE DEEPENING UPPER
TROUGH/LOWS SHOULD FAVOR POCKETS OF RAINFALL INTO FRIDAY AS
MOISTURE GETS WRAPPED BACK INTO ESPECIALLY NORTHERN MAINE FROM A
LINGERING LOW PRESSURE SYSTEM NEAR THE COAST. IN FLORIDA, A
LINGERING WEAK FRONT SHOULD SUPPORT UNSETTLED CONDITIONS OVER THE
SUNSHINE STATE WITH BETTER HEAVY RAIN CHANCES IN SOUTHERN FLORIDA
LATE WEEK AS DEEPER MOISTURE GETS PULLED NORTH.
CENTRAL U.S. RIDGING ALOFT WILL MAINTAIN AN AXIS OF ABOVE NORMAL
TEMPERATURES FROM THE NORTHERN PLAINS SOUTH-SOUTHEAST TO THE
MID-SOUTH, WITH PLUS 5-10F ANOMALIES FOR HIGHS POSSIBLE MOST DAYS.
THE NORTHWEST WILL BE THE OTHER FOCUS FOR VERY WARM TEMPERATURES,
WITH HIGHS 10-20F OR SO ABOVE NORMAL AND MODERATION LATER IN THE
WEEK AS TROUGHING BEGINS TO PUSH INTO THE REGION. EXPECT BELOW
NORMAL TEMPERATURES OVER THE NORTHEAST AND AT TIMES INTO THE
MID-ATLANTIC AS UPPER TROUGHING BECOMES ESTABLISHED. 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 UPPER LOW REACHING SOUTHERN CALIFORNIA MONDAY WILL
ALSO BRING A COOLING TREND INTO THE SOUTHWESTERN U.S. NEXT WEEK.
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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