983
FXUS02 KWBC 062000
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 PM EDT TUE JUN 06 2023
VALID 12Z FRI JUN 09 2023 - 12Z TUE JUN 13 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 SHOULD PERSIST THROUGH THE NEXT WEEK
WITH AN ANOMALOUSLY STRONG UPPER RIDGE/HIGH 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, NOW MORE LIKELY CLOSING OFF A LOW OVER/NEAR THE OHIO
VALLEY INTO EARLY 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
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE BLEND OF WELL CLUSTERED GUIDANCE FROM THE LATEST
GFS/ECMWF/UKMET/CANADIAN, THE NATIONAL BLEND OF MODELS AND WPC
CONTINUITY FROM FRIDAY INTO THE WEEKEND IN AN ACTIVE PATTERN WITH
SEEMINGLY ABOVE NORMAL PREDICTABILITY AND GOOD ENSEMBLE SUPPORT.
MODELS CONTINUE TO OFFER SOME RUN TO RUN VARIABLILITY, WITH TRENDS
TO HOLD CLOSED LOWS OVER CALIFORNIA/SOUTHWEST AND NOW MORE INTO
THE GREAT LAKES WITH THE 12 UTC CYCLE, BUT OVERALL REMAIN
REASONABLY CLUSTERED INTO LONGER TIME FRAMES. FORECAST SPREAD FROM
THE MODELS REMAINS BELOW NORMAL INTO EARLY NEXT WEEK AND BEST IN
LINE WITH ECMWF ENSEMBLES THAT BETTER MAINTAIN THE BLOCKY FLOW
PATTERN THAT SEEMS MUCH MORE REASONABLE VERSUS MORE PROGRESSIVE
LATER PERIOD GUIDANCE FROM RECENT GEFS/CANADIAN ENSEMBLE RUNS AND
ASSCOIATED FORECAST CLUSTERS. HOWEVER, THERE IS AT LEAST SOME RUN
TO RUN TREND FROM GEFS ENSEMBLES TOWARD A SLOWER SOLUTION.
..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 THE NEXT WEEK
AS TROPICAL PACIFIC MOISTURE REMAINS FUNNELED NORTHWARD BETWEEN A
STRONG CENTRAL U.S. RIDGE AND AN UPPER LOW PARKED OVER
CALIFORNIA/SOUTHWEST. THE DAYS 4 AND 5 EXCESSIVE RAINFALL OUTLOOKS
CONTINUE TO DEPICT A LARGE MARGINAL RISK ACROSS THIS ENTIRE REGION
WITH AN EMBEDDED SLIGHT RISK OVER MONTANA FOR DAY 4 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 AND ONWARD ALONG WITH FAVORABLE LEADING INSTABILITY
AND THETAE ADVECTION WITH RETURN FLOW LATER THIS WEEK THROUGH THE
WEEKEND SHOULD FOCUS SHOWERS AND STRONG THUNDERSTORMS. A MARGINAL
RISK REMAINS EXPANDED INTO THIS REGION BY DAY 5 AS MODELS INDICATE
POTENTIAL FOR AT LEAST LOCALLY HEAVY RAINFALL AND CONVECTION.
SLIGHT RISKS ARE POSSIBLE AS WE GET CLOSER IN TIME, BUT AT THIS
POINT, ITS FAR TOO UNCERTAIN TO PICK OUT WHERE THE BEST FOCUS MAY
BE. A LEADING COLD FRONT SETTLING OVER THE SOUTHEAST SHOULD BE A
SECONDARY FOCUS FOR CONVECTION, WITH POSSIBLY MORE
WIDESPREAD/HEAVY SHOWERS ACROSS SOUTHERN FLORIDA LATER THIS WEEK
ALONG A WEAKENING FRONT. MIDWEST 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.
WARMER THAN AVERAGE TEMPERATURES, GENERALLY +10-15F, FROM THE
NORTHERN TIER TO THE NORTHWEST SHOULD MODERATE SOME THIS WEEKEND,
BUT MAY CREEP UP AGAIN EARLY NEXT WEEK. 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.
SCHICHTEL/SANTORELLI
HAZARDS:
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE
MISSISSIPPI VALLEY, THE LOWER MISSISSIPPI VALLEY, AND THE SOUTHERN
PLAINS, SAT, JUN 10.
- HEAVY RAIN ACROSS PORTIONS OF THE NORTHERN PLAINS AND THE
NORTHERN ROCKIES, FRI-SAT, JUN 9-JUN 10.
- HEAVY RAIN ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY, THE
LOWER MISSISSIPPI VALLEY, THE OHIO VALLEY, AND THE TENNESSEE
VALLEY, SUN, JUN 11.
- FLOODING POSSIBLE ACROSS PORTIONS OF THE CENTRAL ROCKIES AND THE
CENTRAL PLAINS.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE NORTHERN
ROCKIES AND THE NORTHERN GREAT BASIN.
- FLOODING LIKELY ACROSS PORTIONS OF THE CENTRAL GREAT BASIN, THE
NORTHERN PLAINS, AND THE NORTHERN GREAT BASIN.
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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