704
FXUS02 KWBC 251927
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
327 PM EDT TUE OCT 25 2022
VALID 12Z FRI OCT 28 2022 - 12Z TUE NOV 01 2022
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE OVERALL SYNOPTIC PATTERN DURING THE MEDIUM RANGE WAS CAPTURED
REASONABLY WELL BY THE EC. THE GENERAL TREND HAS BEEN A SLOWING
ONE ACROSS THE CONUS, WITH AN INCREASE IN QPF IN THE GULF COAST
BEING THE MAIN IMPLICATION. THE PAST SEVERAL RUNS OF THE EC AND
ECE HAVE CONSISTENTLY SIGNALED A SLOW MOVING UPPER LOW TO WEAKEN
AS IT DRIFTS ACROSS THE SOUTHEAST/GULF COAST. THE GFS/CMC/UK SUITE
HAVE BEEN LESS CONSISTENT IN THEIR PLACEMENT OF THE UPPER LOW AND
THE INTENSITY OF IT. THEREFORE, A PREDOMINANTLY 00Z EC/ECE BLEND
WAS UTILIZED THROUGHOUT THE MEDIUM RANGE WITH NO INCLUSION OF THE
00Z CMC. THERE'S A STRONG SIGNAL FOR HEAVY RAINFALL ALONG THE
CENTRAL GULF COAST THIS WEEKEND IN THE 00Z ECE EXCEEDENCE
PROBABILITIES, BUT NOT ENOUGH AGREEMENT FROM THE 00Z GEFS/CMCE TO
WARRANT THE ADDITION OF A SLIGHT RISK AREA. THERE'S A REASONABLE
SIGNAL FOR HEAVY SNOW IN THE DOWNSCALED ENSEMBLE RUNS THROUGH
EARLY NEXT WEEK.
..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
SNOW. 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.
A TARGETED CHANGE WAS MADE TO THE DAY 5 WINTER WEATHER OUTLOOK TO
DEPICT INCREASED DOWNSCALED ENSEMBLE SIGNAL FOR HEAVY SNOW IN THE
NORTHERN CASCADES.
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.
KEBEDE/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