543
FXUS02 KWBC 240701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT MON OCT 24 2022
VALID 12Z THU OCT 27 2022 - 12Z MON OCT 31 2022
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED FROM A
COMPOSITE OF REASONABLY WELL CLUSTERED GUIDANCE FROM THE 18 UTC
GFS AND 12 UTC ECMWF/UKMET/CANADIAN MODELS VALID THURSDAY INTO
FRIDAY ALONG WITH COMPATIBLE INPUT FROM THE 01 UTC NATIONAL BLEND
OF MODELS (NBM) AND WPC CONTINUITY. LATEST 00 UTC MODEL AND
ENSEMBLE GUIDANCE STILL SEEMS IN LINE WITH THIS FORECAST IN A
PATTERN WITH SEEMINGLY ABOVE NORMAL PREDICTABILITY.
FORECAST SPREAD GROWS STEADILY THROUGH THE WEEKEND INTO EARLY NEXT
WEEK, BUT GENERALLY WITHIN NORMAL CONSTRAINTS AND A SOLUTION
CLOSEST TO THE ECMWF ENSEMBLE MEAN WAS PREFERRED AS OF THE
ENSEMBLE SYSTEMS SEEMED OVERALL MOST IIN LINE WITH A MODEL
COMPOSITE AND WPC CONTINUITY.
..PATTERN OVERVIEW AND WEATHER/HAZARD HIGHLIGHTS
A NORTHEASTWARD LIFTING LEAD UPPER TROUGH WILL CLEAR THE NORTHEAST
INTO EASTERN CANADA EARLY THURSDAY ALONG WITH ASSOCIATED ATLANTIC
MOISTURE AND SHOWERS, ALBEIT WITH SOME GREAT LAKE ENHANCEMENT
POSSIBLE IN THE WAKE OF PASSAGE.
SOUTHERN STREAM FLOW AMPLIFICATION/SEPARATIION FROM THE
INTERMOUNTAIN WEST TO THE ROCKIES INTO THURSDAY SETS THE STAGE FOR
COLD TEMPERATURES AND SOME WIDESPREAD PRECIPITATION TO INCLUDE A
TERRAIN ENHANCED HEAVY SNOW THREAT INTO THE SOUTH-CENTRAL ROCKIES.
ADDITIONAL UPSTREAM DIGGING OF PACIFIC SYSTEM/UPPER ENERGIES INTO
THE WEST LATER WEEK INTO EARLY NEXT WEEK REMAINS MORE UNCERTAIN IN
GUIDANCE, BUT THE LESS DEFINED ENSEMBLE MEANS AT LEAST SHOW
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 BROAD TARGETED CHANGE TO NBM QPF WAS
TO TREND AMOUNTS MODESTLY TOWARD WPC QPF CONTINUITY GIVEN RUN TO
RUN FORECAST VARIANCES IN THIS FLOW.
MEANWHILE, THE DOWNSTREAM EJECTION OF A 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 INSTABILIY 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. SLOW SYSTEM TRANSLATION AND POTENTIAL FOR CELL
TRAINING AND REPEAT CELLS COULD LEAD TO LOCAL RUNOFF ISSUES.
ECMWF ENSEMBLES OFFER A RELATIVELY SLOWER MAIN SYSTEM PROGRESSION
COMPARED TO THE GEFS. THE ECMWF ENSEMBLE MEAN TRACK ALSO SEEMS
BEST IN LINE WITH A COMPOSITE OF RECENT GFS/ECMWF/CANADIAN/UKMET
RUNS. THE ECMWF ENSEMBLE MEAN COUPLED WITH SOME STRONGER/MORE
SEPARATED SOUTHERN STREAM SYSTEM DETAIL INPUT FROM A MODEL
COMPOSITE SEEMS TO OFFER A GOOD FORECAST BASIS DESPITE
UNCERTAINTIES. HOWEVER DUE TO FORECAST SPREAD, SUSPECT THAT BOTH
ECMWF ENSEMBLES AND THE 01 UTC NBM MAY BE SPREADING THE ASSOCIATED
QPF FIELD TOO QUICKLY DOWNSTREAM FROM THE SOUTH-CENTRAL U.S. TO
THE EAST LATER WEEKEND INTO EARLY NEXT WEEK GIVEN THE CLOSED
NATURE OF SUPPORTING LOW. THIS PROMPTED AN ASSOCIATED TARGETED
CHANGE TO THE NBM.
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
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page