659
FXUS02 KWBC 250700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT TUE OCT 25 2022
VALID 12Z FRI OCT 28 2022 - 12Z TUE NOV 01 2022
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE OF REASONABLY WELL CLUSTERED GUIDANCE FROM THE 18 UTC
GFS AND 12 UTC ECMWF/UKMET/CANADIAN 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 EARLY PERIOD FORECAST IN A PATTERN WITH
SEEMINGLY ABOVE NORMAL PREDICTABILITY. FORECAST SPREAD GROWS
STEADILY THROUGH THE WEEKEND INTO EARLY NEXT WEEK. A SOLUTION
CLOSEST TO THE ECMWF ENSEMBLE MEAN IS PREFERRED IN THIS PERIOD
WITH LOWERING PREDICTABILITY AS IT STEADILY REMAINS MOST IN LINE
WITH OVERALL PACIFIC SYSTEM TRANSLATIONS INTO THE WEST AND
DOWNSTREAM SOUTHERN STREAM FLOW SEPARATION AND EMBEDDED SYSTEM
STRENGTH/TIMING ASPECTS COMPARED TO WPC CONTINUITY AS WELL AS THE
COMPOSITE OF INCREASING VARIED OVER TIME GFS/ECMWF/UKMET/CANADIAN
MODELS.
..PATTERN OVERVIEW AND WEATHER/HAZARD HIGHLIGHTS
THE ASPECTS OF A SERIES OF PACIFIC SYSTEMS INTO THE WEST/NORTHWEST
HEADING INTO THIS WEEKEND AND THROUGH EARLY NEXT WEEK REMAINS
UNCERTAIN AND MORE RUN TO RUN VARIED THAN NORMAL IN RECENT
GUIDANCE, BUT A GENERAL MODEL CONSENSUS/ECMWF ENSEMBLE MEAN
SUGGESTS A SYSTEM FOCUS FOR PERIODIC MODERATE PRECIPITATION FROM
NORTHERN CALIFORNIA AND THE PACIFIC NORTHWEST INLAND ACROSS THE
NORTHERN GREAT BASIN/ROCKIES TO INCLUDE TERRAIN ENHANCED ELEVATION
SNOWS. LATEST GUIDANCE INCLUDING THE 00 UTC MODEL SUITE SHOWS A
STEADY DIET OF SYSTEMS, BUT WITH THE STRONGEST SYSTEM
PASSAGE/HEIGHT FALL FOCUS SEEMINGLY ON TAP FOR SUNDAY INTO MONDAY.
OVERALL, 01 UTC NBM QPF SEEMS BROADLY REASONABLE WITH THIS
SCENARIO, CONTINUITY AND MESSAGING, SO TARGETED CHANGES WERE NOT
APPLIED.
MEANWHILE, A LEADING CLOSED/SEPARATED SOUTHERN STREAM SYSTEM
REMAINS SLATED TO SLOWLY TRACK ACROSS THE SOUTH-CENTRAL U.S.
FRIDAY AND FOR THE WEEKEND BEFORE LIFTING/SHEARING NORTHEASTWARD
TOWARD THE APPALACHIANS BY NEXT TUESDAY. THIS WILL ACT TO FOCUS
SOME ENHANCED RAIN/CONVECTION GIVEN UPPER AND SURFACE SYSTEM
SUPPORT TO POOL MOISTURE/INSTABILITY TO FUEL ACTIVITY. THERE IS A
SOME GUIDANCE SIGNAL FOR LOCALLY MODERATE TO HEAVY RAINFALL GIVEN
THE RISK OF REPEAT/TRAINING CELLS WITH OVERALL SLOW SYSTEM
TRANSLATION, ALBEIT WITH DETAILS LESS CERTAIN GIVEN THE NATURE OF
CLOSED FEATURES. GUIDANCE SHOWS THE GREATEST CONSENSUS ON THE
POTENTIAL FOR HIGHER RAIN RATES AND MORE THAN A COUPLE INCHES OF
RAIN ON FRIDAY, WHICH DESPITE OVERALL DRY ANTECEDENT CONDITIONS,
COULD BE ENOUGH TO LEAD TO AT LEAST A FEW LOCAL INSTANCES OF FLASH
FLOODING. THIS OFTEN HAPPENS WITH CLOSED SYSTEMS. WEEKEND TO EARLY
NEXT WEEK RAINFALL FROM THE SOUTH NORTHEASTWARD INTO THE EAST WERE
ADJUSTED SLOWER AND ACCORDINGLY INCREASED RELATIVE TO THE NBM
ALONG THE TRACK OF THE SYSTEM CONSIDERING TRENDS FROM
DETERMINISTIC GUIDANCE AND THE ECMWF ENSEMBLE MEAN. 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.
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
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