975
FXUS02 KWBC 241935
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
334 PM EDT MON OCT 24 2022
VALID 12Z THU OCT 27 2022 - 12Z MON OCT 31 2022
..GUIDANCE AND PREDICTABILITY ASSESSMENT
MODEL GUIDANCE WAS RELATIVELY CONSISTENT EARLY IN THE PERIOD WITH
A GRADUAL INCREASE IN SPREAD MAINLY RELATED TO THE PROGRESSION OF
A TROUGH/CLOSED LOW OVER THE SOUTHERN CONUS. A GENERAL MODEL BLEND
BETWEEN THE 06 UTC GFS AND THE 00 UTC CMC/ECMWF/UKMET WAS USED
EARLY IN THE PERIOD WITH GUIDANCE DEPICTING A DEEPENING TROUGH
MOVING FROM THE WEST OUT OVER THE PLAINS THURSDAY INTO FRIDAY,
WITH A CLOSED LOW DEVELOPING OVER THE SOUTHERN PLAINS. THE 00 UTC
ECMWF ENSEMBLE MEAN WAS STEADILY INCREASED IN THE BLEND AS IT
FOLLOWED THE 06 UTC GFS AND 00 UTC CMC WITH A MORE PROGRESSIVE
TROUGH MOVING INTO THE EASTERN CONUS. THE 00 UTC ECMWF WAS AN
OUTLIER IN SHOWING A SLOWER PROGRESSION AND DEEPER CLOSED LOW
LATER INTO THE PERIOD. RELIANCE TOWARD THE END OF THE PERIOD ON
THE 06 UTC GFS, 00 UTC ECMWF ENSEMBLE MEAN, AND 00 UTC GEFS MEAN
HELPED TO INDICATE THE DEVELOPMENT OF ANOTHER LESS AMPLIFIED
TROUGH ALONG THE WEST COAST WHILE THE 00 CMC WAS REMOVED FROM THE
BLEND AS IT DIFFERED WITH SUBTLE RIDGING INDICATED. THE 00 UTC
ECMWF WAS ALSO AN OUTLIER AS IT DEVELOPED A MUCH DEEPER UPSTREAM
PACIFIC SYSTEM LATE IN THE PERIOD.
..PATTERN OVERVIEW AND WEATHER/HAZARD HIGHLIGHTS
A NORTHEASTWARD LIFTING LEAD UPPER TROUGH WILL CLEAR THE NORTHEAST
INTO EASTERN CANADA EARLY THURSDAY ALONG WITH HIGH PRESSURE
DEVELOPING OVER THE REGION. TEMPERATURES LOOK TO BE GENERALLY AT
OR JUST ABOVE AVERAGE FOR MID-FALL WITH THE ONLY PRECIPITATION
CHANCES INCREASING LATER IN THE PERIOD MONDAY INTO TUESDAY.
SOUTHERN STREAM FLOW AMPLIFICATION/SEPARATION FROM THE
INTERMOUNTAIN WEST TO THE ROCKIES INTO THURSDAY SETS THE STAGE FOR
COLD TEMPERATURES AND THE CHANCE FOR SOME SNOW IN THE
SOUTH-CENTRAL ROCKIES. THE ADDITIONAL UPSTREAM DIGGING OF ANOTHER
PACIFIC SYSTEM/UPPER ENERGIES INTO THE WEST LATER WEEK INTO EARLY
NEXT WEEK REMAINS A BIT MORE UNCERTAIN IN GUIDANCE, BUT A GENERAL
MODEL CONSENSUS SHOWS POTENTIAL ENERGY AVAILABLE ALONG WITH A
PERIODIC MODERATE QPF SIGNATURE BACK ACROSS MAINLY THE NORTHWEST
AND INLAND INTO THE NORTH-CENTRAL GREAT BASIN AND ROCKIES TO ALSO
INCLUDE SOME TERRAIN ENHANCED ELEVATION SNOWS. A GENERAL MODEL
BLEND WAS USED ALONG WITH THE NBM TO KEEP CONTINUITY WITH THE
PREVIOUS FORECAST AND HELP SPREAD AMOUNTS OUT ACROSS THE REGION AS
THE LOCATION OF ANY LOCALLY HEAVIER QPF WAS UNCERTAIN.
MEANWHILE, THE DOWNSTREAM EJECTION OF THE LIKELY CLOSED/WELL
SEPARATED SOUTHERN STREAM SYSTEM REMAINS SLATED TO TRACK STEADILY
OVER THE SOUTH-CENTRAL AND SOUTHERN U.S. LATE WEEK THROUGH THE
WEEKEND TO FOCUS ENHANCED RAIN/CONVECTION GIVEN UPPER SUPPORT AND
POOLING MOISTURE AND INSTABILITY TO FUEL ACTIVITY. THE GUIDANCE
SIGNAL FOR LOCALLY MODERATE TO HEAVY RAINFALL CONTINUES TO
INCREASE, ALBEIT WITH DETAILS LESS CERTAIN GIVEN THE NATURE OF
CLOSED FEATURES AND HOW PROGRESSIVE THE SYSTEM IS. THE QPF
FORECAST TRENDED HIGHER AND FURTHER EAST THAN THE NBM/PREVIOUS
FORECAST BY INCORPORATING MORE OF THE DETERMINISTIC GUIDANCE AND
THE ECMWF MEAN WHICH INCLUDED MORE LOCALLY ENHANCED TOTALS THROUGH
THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY. MODEL GUIDANCE
SHOWED THE GREATEST CONSENSUS ON THE POTENTIAL FOR HIGHER RAIN
RATES AND MORE THAN A COUPLE INCHES OF RAIN ON FRIDAY, WHICH,
DESPITE DROUGHT CONDITIONS, COULD BE ENOUGH TO LEAD TO AT LEAST A
FEW LOCAL INSTANCES OF FLASH FLOODING. QPF AMOUNTS ACROSS THE EAST
WERE ALSO INCREASED RELATIVE TO THE NBM ALONG THE TRACK OF THE
SYSTEM AS IT PROGRESSES THROUGH THE SOUTHEAST SUNDAY AND MONDAY AS
THE DETERMINISTIC GUIDANCE AND ECMWF ENSEMBLE MEAN INDICATED THE
POTENTIAL FOR LOCALLY HEAVIER TOTALS. HOWEVER, AS EXPECTED
COMPARED TO EARLIER IN THE PERIOD, THE LOCATION OF ANY ENHANCED
RAINFALL IS MORE UNCERTAIN AND A BROAD AREAL AVERAGE INCREASE WAS
INCLUDED FOR NOW.
PUTNAM/SCHICHTEL
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, FRI-SAT,
OCT 28-OCT 29.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST.
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL
ROCKIES, THE CENTRAL GREAT BASIN,
THE NORTHERN ROCKIES, THE SOUTHERN ROCKIES, THE NORTHERN GREAT
BASIN, THE SOUTHERN PLAINS, AND THE
SOUTHWEST, THU-SAT, OCT 27-OCT 29.
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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