359
FXUS02 KWBC 052056
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
455 PM EDT MON JUN 05 2023
VALID 12Z THU JUN 08 2023 - 12Z MON JUN 12 2023
...A MULTI-DAY THUNDERSTORM AND LOCAL HEAVY RAIN THREAT WILL
CONTINUE REST OF THIS NEXT WEEK FROM THE NORTHERN ROCKIES THROUGH
PORTIONS OF THE GREAT PLAINS...
..OVERVIEW
A VERY AMPLIFIED AND BLOCKY FLOW PATTERN PERSISTS OVER NORTH
AMERICA WITH AN ANOMALOUSLY STRONG UPPER RIDGE/HIGH SANDWICHED
BETWEEN MEAN TROUGHING/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 THROUGH FRIDAY. THE NEXT WAVE
ROUNDING THE MID-CONTINENTAL RIDGE CROSSES ONTARIO AND APPROACHES
THE NORTHEAST THIS WEEKEND. THIS ALLOWS THE PRECIP FOCUS TO SHIFT
EAST FROM THE ROCKIES AND APPROACH THE EASTERN SEABOARD BY EARLY
NEXT WEEK.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
A GENERAL MODEL BLEND OF THE 00Z/06Z DETERMINISTIC SOLUTIONS
WORKED WELL FOR DAYS 4-6 AMIDST GOOD MODEL AGREEMENT ON THE RATHER
STATIC PATTERN THROUGH FRIDAY AND THE PROGRESSION OF THE NEXT
TROUGH ROUNDING THE MID-CONTINENTAL RIDGE AND CROSSING ONTARIO ON
APPROACH OF THE NORTHEAST ON SATURDAY. HOWEVER, BY DAY 7 SPREAD
INCREASES ON THE PROGRESSION AND DEPTH OF THE TROUGH/LOW.
FURTHERMORE, 12Z GUIDANCE DISPLAYS GREATER SPREAD WITH THIS
FEATURE. THE 12Z ECMWF IS NOW MORE CLOSED/SLOWER WITH THE LOW OVER
THE GREAT LAKES WITH ALL GUIDANCE GENERALLY MAINTAINING THE
MID-CONTINENTAL RIDGE. OUT WEST, THE UPPER LOW CURRENTLY OVER
CALIFORNIA SHOULD WEAKEN AND LIFT NORTH BU THURSDAY AS A SECOND
PIECE OF ENERGY CUTS OFF FROM EASTERN PACIFIC TROUGHING TO CLOSE
OFF A DEEP LOW OVER SOUTHERN CALIFORNIA BY THIS WEEKEND, LIKELY
LINGERING INTO NEXT WEEK. THE WPC BLEND INCREASED GEFS/ECENS
ENSEMBLE MEANS LATE PERIOD GIVEN MINOR MODEL DIFFERENCES AS WELL
AS THE LACK OF THE UKMET BEYOND DAY 5.
..WEATHER/HAZARDS HIGHLIGHTS
THE DAILY DIURNAL RISK FOR HEAVY SHOWERS AND THUNDERSTORMS FROM
THE SOUTHERN PLAINS THROUGH THE NORTHERN ROCKIES AND WESTWARD INTO
THE GREAT BASIN PERSISTS THROUGH AT LEAST FRIDAY AS TROPICAL
PACIFIC MOISTURE IS FUNNELED NORTHWARD 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. EMBEDDED SLIGHT RISKS
WERE MAINTAINED OVER WEST-CENTRAL 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. HOWEVER, THE SLIGHT RISK AREAS
WERE WITHDRAWN FROM THE ABSAROKAS/YELLOWSTONE GIVEN FAR LOWER SNOW
PACK IN THE AREA COMPARED TO LAST YEAR ALONG WITH UNFOCUSED
DIURNAL RAINFALL THREATS.
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, THOUGH TEMPERATURES WILL MODERATE SOME ACROSS THE
GREAT LAKES THIS WEEKEND AS THE RIDGE AXIS SHIFTS WEST. 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.
JACKSON
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
HAZARDS:
- HEAVY RAIN ACROSS PORTIONS OF THE NORTHERN PLAINS/ROCKIES,
THU-FRI, JUN 8-JUN 9.
- FLOODING POSSIBLE ACROSS PORTIONS OF THE NORTHERN
PLAINS/ROCKIES/GREAT GREAT BASIN.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE NORTHERN
ROCKIES/GREAT BASIN.
- FLOODING LIKELY ACROSS PORTIONS OF THE CENTRAL GREAT BASIN, THE
NORTHERN PLAINS GREAT BASIN.
- MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHERN
ROCKIES AND THE NORTHERN GREAT
BASIN, THU, JUN 8.
- HEAVY RAIN ACROSS PORTIONS OF MAINLAND ALASKA, THU, JUN 8.
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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