225
FXUS02 KWBC 212031
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
331 PM EST MON NOV 21 2022
VALID 12Z THU NOV 24 2022 - 12Z MON NOV 28 2022
...A COUPLE OF LOW PRESSURE SYSTEMS INCLUDING A POSSIBLE
NOR'EASTER COULD CAUSE MEANINGFUL PRECIPITATION ACROSS
CENTRAL/EASTERN PARTS OF THE U.S. LATE THIS WEEK...
..OVERVIEW
THE START OF THE EXTENDED PERIOD WILL HAVE AN AMPLIFIED UPPER
PATTERN ACROSS CONTIGUOUS STATES WITH A RIDGE ATOP THE WEST AND A
DEEPENING TROUGH ACROSS CENTRAL PARTS OF THE COUNTRY. ALTHOUGH
THERE IS A SIGNIFICANT AMOUNT OF MODEL SPREAD WITH HOW THIS TROUGH
DEVELOPS AND HOW FAST IT TRACKS TO THE EAST, IT WILL HAVE THE
POTENTIAL TO SPREAD MODEST TO POSSIBLY HEAVY PRECIPITATION WITH IT
FROM THE SOUTHERN PLAINS POSSIBLY TO THE NORTH EAST. WPC HAS BEEN
FAVORING A SURFACE LOW PRESSURE SYSTEM MOVING EAST ACROSS THE
GREAT LAKES OR NEARBY WITH A COLD FRONT PASSING ACROSS THE
CENTRAL-EASTERN U.S. AND PHASING WITH ANOTHER LOW TRACKING
NORTHWARD NEAR THE ATLANTIC COAST, LEADING TO A POTENTIALLY STRONG
STORM AFFECTING NEW ENGLAND DURING THE WEEKEND. HOWEVER, THERE IS
THE POSSIBILITY FOR A SLOWER/SOUTHERN AREA OF SIGNIFICANT RAINFALL
AND LESS PRECIPITATION/SURFACE LOW DEVELOPMENT OVER THE NORTHEAST.
BY EARLY NEXT WEEK, THE UPPER PATTERN IS LIKELY TO TRANSITION TO
MORE ZONAL FLOW, BUT WITH EVENTUAL TROUGHING AND FRONTS COMING
INTO THE NORTHWEST PROMOTING INCREASING PRECIPITATION CHANCES
THERE.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE LATEST GUIDANCE CONTINUE TO SHOW AN UPPER LOW DEVELOP AND
CLOSE OFF EARLY IN THE EXTEND PERIOD AND WILL TRACK EAST/NORTHEAST
UNTIL THE END OF THE FORECAST EARLY NEXT WEEK. THERE IS A VERY
SIGNIFICANT DEGREE OF SPREAD WITH THIS LOW FEATURE WHICH YIELDS A
LOW CONFIDENCE FORECAST IN TERMS OF THE DETAILS/SPECIFICS WITH
EACH FEATURE. THE ECWMF IS THE MOST PROGRESSIVE OF THE GLOBAL. IT
CLOSES OFF THE UPPER LOW OVER THE CENTRAL U.S. AND KEEP TRACKING
NORTHEAST ACROSS THE GREAT LAKES AND THE NORTHEAST. THIS PLACES
THE QPF FOOTPRINT OVER THE EASTERN GULF STATES AND MAINLY EAST OF
THE APPALACHIANS, ALONG WITH THE POTENTIAL FOR A COAST SYSTEM. THE
CMC IS THE FIRST TO CLOSE OFF THE UPPER LOW AND FAVOR A
SLOWER/DEEPER PROGRESSION ACROSS THE SOUTHERN ROCKIES AND INTO THE
SOUTHERN PLAINS. THE GFS IS ABOUT 6 HOURS BEHIND THE CMC BUT
FAVORS A SIMILAR TREND TO THE CMC. THE UKMET DEPICTS A CLOSED OFF
SYSTEM BUT DOES SO OVER THE SOUTHERN/CENTRAL PLAINS AND IS A
LITTLE MORE PROGRESSIVE THAN THE CMC/GFS SOLUTIONS. THIS DEGREE OF
SPREAD EITHER HAS LITTLE TO NOR PRECIPITATION OVER TEXAS/WESTERN
GULF WITH ALL OF THE QPF SPANNING FROM THE EASTERN GULF
STATES/SOUTHEAST AND UP THE EAST COAST PER THE ECWMF. OR,
SCATTERED TO WIDESPREAD PRECIPITATION OVER PORTIONS OF THE
SOUTHERN/CENTRAL PLAINS, GULF COAST AND INTO THE
MISSISSIPPI/TENNESSEE VALLEYS PER THE CMC/GFS AND SOMEWHAT PER THE
UKMET.
BOTH TYPES OF SCENARIOS CAN AND DO HAPPEN DOWNSTREAM OF RIDGING SO
THERE IS LOW CONFIDENCE IN WHICH TO CHOOSE. AT THE SURFACE, THERE
HAS BEEN SOME WAFFLING WITH THE PLACEMENT OF LOWS AS WELL OF
COURSE, INITIALLY WITH A GREAT LAKES OR SOUTHERN CANADA LOW THAT
OVERALL SEEMED TO BOUNCE BACK SOUTH. THE PREVIOUS FORECAST LEANED
TOWARD THE ECMWF-LED PHASED TROUGH SOLUTION YIELDING A POSSIBLY
DEEP SURFACE LOW IN THE NORTHEAST. HOWEVER THE 00Z RUN SEEMS TO BE
MORE OF THE OUTLIER SOLUTION GIVEN THE THE GFS IS FAVORING A
SIMILAR TRACK AS THE CMC AND THE UKMET IS CLOSER TO THOSE TWO
WITHIN THE CLUSTER THAN IT IS TO THE ECWMF. THE 12Z RUN OF THE
ECWMF HAS STARTED TO TREND TOWARD HAVING A CLOSED LOW IN THE
VICINITY OF WEST TEXAS AND NOT AS PROGRESSIVE OF AN EVOLUTION. SO,
ALL IN ALL, THIS PACKAGE DOES BREAK FROM WPC CONTINUITY BY
UTILIZING MORE OF THE GFS AND CMC DURING THE EARLY AND MIDDLE
PERIODS. THE MODEL BLEND WAS BASED ON A BLEND OF THE 00Z
ECWMF/CMC,UKMET, 00Z/06Z GFS AND THE GEFS AND EC ENSEMBLE MEANS.
FOR QPF, BLENDED IN A CONSIDERABLE AMOUNT OF THE CMC, GFS WITH
LIGHTER WEIGHTING OF ECMWF. AFTER THAT BY EARLY NEXT WEEK, THE
OVERALL PATTERN IS LIKELY TO FLATTEN BUT WITH SOME EMBEDDED
SHORTWAVES, AND MORE LONGWAVE RIDGING SHOULD COME INTO THE
NORTHWEST AROUND DAY 7/MONDAY.
..WEATHER/HAZARD HIGHLIGHTS
AS THE UPPER TROUGH AMPLIFIES EAST OF THE ROCKIES BY THANKSGIVING
DAY AND BEYOND, GULF MOISTURE SHOULD STREAM INTO THE EASTERN HALF
OF THE U.S. AHEAD OF THE TROUGH. THE SOUTHEASTERN QUADRANT OF THE
U.S. NORTHWARD INTO THE OHIO VALLEY AND GREAT LAKES MAY SEE SOME
PRECIPITATION AROUND THANKSGIVING, WHILE HEAVIER PRECIPITATION
LOOKS MORE LIKELY ACROSS THE LOWER MISSISSIPPI VALLEY TO THE
MID-ATLANTIC ON FRIDAY. CURRENT FORECASTS CONTINUE TO INDICATE
THAT WINTRY PRECIPITATION IS A BETTER POSSIBILITY FOR THE INTERIOR
NORTHEAST WHILE THE METROPOLITAN AREAS ALONG THE I-95 CORRIDOR ARE
MORE LIKELY TO GET RAIN. BUT STAY TUNED TO FUTURE FORECASTS AS
THESE UNCERTAIN DETAILS LIKE PRECIPITATION TYPES IN PARTICULAR
AREAS COULD CHANGE AS MODEL GUIDANCE EVENTUALLY COMES INTO BETTER
CONSENSUS WITH LOW TRACKS AND TEMPERATURES. DEPENDING ON THE
STRENGTH OF ONE OR MORE LOW PRESSURE CENTERS, WINDS COULD BECOME
BRISK TO STRONG FOR A TIME. ALSO NOTE THAT THERE IS STILL
POTENTIAL FOR SIGNIFICANTLY DIFFERENT PRECIPITATION COVERAGE AND
AMOUNTS, WHICH WOULD INVOLVE MORE RAINFALL ACROSS THE SOUTHERN
TIER FROM TEXAS ACROSS THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST,
AND LOWER TOTALS (WITH WEAKER/MORE OFFSHORE LOW PRESSURE) FARTHER
NORTH.
THEN BY NEXT WEEKEND, LAKE EFFECT SNOW IS ONCE AGAIN A POSSIBILITY
BEHIND THE UPPER TROUGH. THE NORTHWEST MAY SEE A BRIEF PERIOD OF
DRY WEATHER BUT MOISTURE COULD RETURN INTO WESTERN WASHINGTON AS
SOON AS THANKSGIVING DAY, WITH A SERIES OF FRONTAL SYSTEMS
SPREADING RAIN AND HIGH ELEVATION SNOW ACROSS MORE OF THE
NORTHWEST AND EVENTUALLY NORTHERN CALIFORNIA THROUGH THE WEEKEND,
WITH EXPANDING COVERAGE INTO THE GREAT BASIN/ROCKIES EARLY NEXT
WEEK.
TEMPERATURES ARE LIKELY TO TREND ABOVE AVERAGE ALONG THE WEST
COAST BY THURSDAY WITH PLUS 5-15F ANOMALIES EXPANDING INTO THE
ROCKIES AND CENTRAL U.S. LATER IN THE WEEK AS THE UPPER RIDGE
BUILDS IN. WESTERN U.S. TEMPERATURES SHOULD TREND BACK TOWARD
NORMAL AND PERHAPS BELOW AVERAGE BY EARLY NEXT WEEK GIVEN THE
LATEST FORECAST OF UPPER FLOW BECOMING MORE ZONAL AND EVENTUALLY
SWITCHING TO A TROUGH PATTERN. FARTHER EAST, POST-FRONTAL COOLER
TEMPERATURES ESPECIALLY IN TERMS OF HIGHS SHOULD EXTEND FROM THE
MISSISSIPPI VALLEY TOWARD THE EAST COAST FRIDAY-SATURDAY AS THE
UPPER TROUGH IS LIKELY TO MOVE THROUGH. ANOMALIES WILL DEPEND UPON
THE DETAILS OF THE EASTERN U.S. UPPER TROUGH AND POTENTIAL EAST
COAST SYSTEM, WHICH ARE STILL QUITE UNCERTAIN.
CAMPBELL/TATE/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 PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND
THE NORTHERN GREAT BASIN, SAT-SUN, NOV 26-NOV 27.
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL GREAT BASIN,
CALIFORNIA, AND THE SOUTHWEST, MON, NOV 28.
- HEAVY RAIN ACROSS PORTIONS OF THE PACIFIC NORTHWEST, SAT-SUN,
NOV 26-NOV 27.
- HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE
TENNESSEE VALLEY, THE MID-ATLANTIC, THE SOUTHERN APPALACHIANS, THE
SOUTHEAST, AND THE SOUTHERN PLAINS, THU-FRI, NOV 24-NOV 25.
- HEAVY SNOW ACROSS PORTIONS OF THE SOUTHERN PLAINS, THU-FRI, NOV
24-NOV 25.
- FLOODING POSSIBLE ACROSS PORTIONS OF THE SOUTHEAST.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST.
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PANHANDLE,
THU-FRI, NOV 24-NOV 25.
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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