220
FXUS02 KWBC 252009
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
308 PM EST FRI NOV 25 2022
VALID 12Z MON NOV 28 2022 - 12Z FRI DEC 02 2022
...SNOW LIKELY ACROSS HIGHER ELEVATIONS OF THE WEST INTO NEXT
WEEK...
...HEAVY RAIN AND SEVERE WEATHER POSSIBLE ACROSS PARTS OF THE
SOUTH AND INTO THE OHIO VALLEY TUESDAY-WEDNESDAY NEXT WEEK...
..OVERVIEW
LATEST GUIDANCE AGREES FAIRLY WELL FOR THE LARGE SCALE PATTERN
THAT SHOULD FEATURE MEAN TROUGHING OVER THE WEST AND AN INITIAL
BAHAMAS/CUBA UPPER RIDGE ULTIMATELY BUILDING WESTWARD OVER THE
GULF OF MEXICO. WITHIN THIS PATTERN, FEATURES ACROSS THE LOWER 48
SHOULD BE PROGRESSIVE. LEADING NEW ENGLAND LOW PRESSURE AND
TRAILING FRONT SHOULD QUICKLY DEPART AFTER EARLY MONDAY. THEN
WESTERN-CENTRAL U.S. TROUGH ENERGY DURING THE FIRST HALF OF THE
WEEK SHOULD SPREAD RAIN AND MOUNTAIN SNOW ACROSS THE NORTH-CENTRAL
WEST COAST INTO CENTRAL ROCKIES, AND THEN SUPPORT DEEPENING
SURFACE LOW PRESSURE THAT TRACKS FROM THE CENTRAL PLAINS INTO THE
GREAT LAKES TUESDAY-WEDNESDAY. THE TRAILING COLD FRONT MAY FOCUS
HEAVY RAINFALL FROM THE SOUTH INTO THE OHIO VALLEY, WITH SEVERE
WEATHER ALSO POSSIBLE OVER SOUTHERN AREAS, WHILE SOME SNOW WILL BE
POSSIBLE NORTH/WEST OF THE LOW TRACK. ANOTHER SYSTEM MOVING INTO
THE WEST DURING THE LATTER HALF OF THE WEEK MAY SPREAD
PRECIPITATION FARTHER TO THE SOUTH AND EAST ACROSS THE REGION. THE
OVERALL PATTERN WILL FAVOR BELOW NORMAL TEMPERATURES OVER MUCH OF
THE WEST AND PARTS OF THE HIGH PLAINS, WITH MONTANA AND NEARBY
AREAS LIKELY TO SEE THE MOST PERSISTENT AND COLDEST ANOMALIES.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE FIRST PRIMARY FORECAST ISSUE INVOLVES THE COMBINATION OF
TROUGH ENERGY REACHING THE WEST EARLY IN THE WEEK AND A SMALL
UPPER LOW FARTHER EAST NEAR THE CANADIAN BORDER (WITH ITS OWN
SURFACE SYSTEM), WITH THESE SUBTLE DETAILS HAVING A MEANINGFUL
IMPACT ON THE DEPTH AND TRACK OF CENTRAL PLAINS THROUGH GREAT
LAKES LOW PRESSURE TUESDAY-WEDNESDAY. LATEST GFS RUNS INCLUDING
THE NEW 12Z VERSION ARE ON THE WEAKER (AND SOUTH) SIDE WHILE
PASSING THROUGH THE GREAT LAKES BUT EVENTUALLY STRENGTHEN MORE
OVER CANADA. THE REST OF THE DETERMINISTIC MODELS (ESPECIALLY THE
UKMET AND ECMWF) SHOW THIS SYSTEM DEEPENING QUICKER OVER THE GREAT
LAKES AROUND NEXT WEDNESDAY. HOWEVER, THESE IMPORTANT DETAILS ARE
SUFFICIENTLY SMALL IN SCALE TO HAVE LOW PREDICTABILITY SEVERAL
DAYS OUT IN TIME SO AN INTERMEDIATE APPROACH FOR DEPTH AND TRACK
APPEARS REASONABLE AT THIS TIME. THIS WAS ACHIEVED BY AN
OPERATIONAL MODEL COMPOSITE AS THE STARTING POINT FOR THE FORECAST
INTO EARLY DAY 5 WEDNESDAY.
THE NEXT TROUGH ENTERING THE NORTHWEST AROUND WEDNESDAY NEXT WEEK
COTINUES TO SHOW MORE VARIABILITY IN TERMS OF TRACK AND TIMING.
THE LATEST CMC RUNS CONTINUE TO BE QUICKER WITH THE INITIAL TROUGH
AND THEN ANOTHER REINFORCING SHORTWAVE LATER IN THE WEEK.
MEANWHILE, THE GFS AND ECMWF SUGGEST A LITTLE SLOWER PROGRESSION
THROUGH THE NORTHWEST WITH MORE OF A SOUTH COMPONENT INTO POSSIBLY
NORTHERN CALIFORNIA NEXT FRIDAY. THE ENSEMBLE MEANS SHOW THIS SAME
VARIBILITY, WITHE THE GEFS MEAN A LITTLE MORE PROGRESSIVE THAN THE
GFS, BUT THE ECENS MEAN SUGGESTING A SOUTHWARD SHIFT LIKE THE
ECMWF.
DESPITE THE DIFFERENCES, A GENERAL MODEL COMPOSITE BLEND FOR DAY
3-5 WORKED WELL, WITH MORE EMPHASIS TOWARDS THE ECMWF. BY THE END
OF NEXT WEEK, INCREASED CONTRIBUTION FROM THE MEANS, ALONG WITH
THE GFS AND ECMWF. THE CMC WAS REMOVED AFTER DAY 5 DUE TO ITS
ISSUES WITH LATE WEEK TROUGHING IN THE WEST. OVERALL, THIS
APPROACH MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS SHIFT AS
WELL.
..WEATHER/HAZARD HIGHLIGHTS
EXPECT THE WESTERN U.S. TO SEE TWO PRIMARY PRECIPITATION EVENTS
NEXT WEEK. THE FIRST SHOULD SPREAD RAIN AND MOUNTAIN SNOW FROM
PARTS OF THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA THROUGH THE
GREAT BASIN AND CENTRAL ROCKIES MONDAY-TUESDAY, WITH HIGHEST
TOTALS OVER FAVORED TERRAIN FROM THE OREGON CASCADES INTO THE
CENTRAL THIRD OF THE ROCKIES. THE NEXT AREA OF MOISTURE SHOULD
ARRIVE INTO THE PACIFIC NORTHWEST ON TUESDAY AND THEN EXPAND
STEADILY SOUTHEASTWARD ACROSS THE WEST THROUGH THE REST OF THE
WEEK. SOME PRECIPITATION MAY BE ON THE LOCALLY MODERATE TO HEAVY
SIDE OVER THE PACIFIC NORTHWEST TUESDAY-WEDNESDAY, WITH DECLINING
CONFIDENCE IN THE COVERAGE AND INTENSITY ELSEWHERE LATER IN THE
WEEK DUE TO UNCERTAINTY IN UPPER TROUGH DETAILS. PRECIPITATION
COULD REACH AS FAR SOUTH AS CENTRAL OR SOUTHERN CALIFORNIA LATE
WEEK. SNOW LEVELS IN THE NORTHWEST COULD LOWER TO FAIRLY LOW
ELEVATIONS TOWARD THE END OF THE WEEK.
DURING TUESDAY-WEDNESDAY, STRENGTHENING CENTRAL PLAINS INTO GREAT
LAKES LOW PRESSURE AS WELL AS ITS TRAILING COLD FRONT PLUS A
SEPARATE WARM FRONT LIFTING THROUGH GULF OF MEXICO WILL LIKELY
BRING PRECIPITATION TO MUCH OF THE EASTERN HALF OF THE LOWER 48.
WIDESPREAD AND POTENTIALLY HEAVY RAINFALL IS POSSIBLE FROM THE
LOWER MISSISSIPPI VALLEY INTO THE SOUTHERN APPALACHIANS AND
POTENTIALLY SOME LOCATIONS FARTHER NORTH AS WELL. SUFFICIENT
MOISTURE AND INSTABILITY IN THE WARM SECTOR COULD ALSO LEAD TO
SEVERE WEATHER, WITH THE STORM PREDICTION CENTER ALREADY
HIGHLIGHTING THE CHANCE IN THEIR OUTLOOK FOR NEXT TUESDAY ACROSS
PARTS OF EASTERN TEXAS INTO THE LOWER MISSISSIPPI VALLEY. THERE
ALSO REMAINS POTENTIAL FOR SNOW TO THE NORTHWEST OF THE SURFACE
LOW TRACK WITH A POSSIBLE FOCUS OVER THE UPPER MIDWEST. DETAILS ON
THIS SNOW POTENTIAL WILL BECOME BETTER DEFINED ONCE GUIDANCE SHOWS
BETTER CLUSTERING FOR TRACK AND DEPTH. FINALLY, THIS STORM MAY
PRODUCE STRONG WINDS OVER SOME AREAS OF THE SOUTHWEST AND ALSO
ACROSS THE GREAT LAKES.
MUCH OF THE WEST AND PORTIONS OF THE HIGH PLAINS SHOULD SEE BELOW
NORMAL TEMPERATURES FOR MOST OF NEXT WEEK. COLDEST ANOMALIES WILL
GENERALLY CORRESPOND TO THE TWO PRIMARY UPPER TROUGHS AFFECTING
THE REGION, ESPECIALLY ON TUESDAY AND FRIDAY WHEN THE GREATEST
COVERAGE OF HIGHS 20-30F BELOW NORMAL IS LIKELY OVER MONTANA AND
ALSO FARTHER SOUTH/SOUTHEAST ON TUESDAY. EXPECT HIGHS 10-20F BELOW
NORMAL OVER THE INTERIOR WEST ON TUESDAY AND THE NORTHWEST/GREAT
BASIN ON FRIDAY. MEANWHILE, THE SOUTH-CENTRAL AND EAST-CENTRAL
U.S. WILL LIKELY SEE A BRIEF PERIOD OF ABOVE NORMAL TEMPERATURES
(UP TO PLUS 10-15F ANOMALIES FOR HIGHS AND SLIGHTLY WARMER FOR
MORNING LOWS) ON TUESDAY-WEDNESDAY AHEAD OF THE SYSTEM EMERGING
FROM THE WEST/PLAINS. THEN THE COLD AIR BEHIND THE FRONT WILL DROP
READINGS OVER MOST OF THESE AREAS TO BELOW NORMAL BY NEXT THURSDAY.
SANTORELLI/RAUSCH
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 SOUTHEAST, THE SOUTHERN
APPALACHIANS, THE LOWER MISSISSIPPI
VALLEY, THE SOUTHERN PLAINS, AND THE TENNESSEE VALLEY, TUE-WED,
NOV 29-NOV 30.
- HEAVY SNOW ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND THE
NORTHERN GREAT BASIN, TUE-WED, NOV
29-NOV 30.
- HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES AND THE
NORTHERN GREAT BASIN, WED-THU, NOV
30-DEC 1.
- SEVERE WEATHER ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY,
THE TENNESSEE VALLEY, THE MIDDLE
MISSISSIPPI VALLEY, THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE
OHIO VALLEY, TUE, NOV 29.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST.
- HIGH WINDS ACROSS PORTIONS OF THE SOUTHERN ROCKIES, THE SOUTHERN
PLAINS, AND THE SOUTHWEST, TUE,
NOV 29.
- HIGH WINDS ACROSS PORTIONS OF THE NORTHEAST AND THE GREAT LAKES,
WED, NOV 30.
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE PACIFIC
NORTHWEST, THE NORTHERN ROCKIES,
THE NORTHERN GREAT BASIN, AND THE NORTHERN PLAINS, FRI, DEC 2.
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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