564
FXUS02 KWBC 031846
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
145 PM EST FRI FEB 03 2023
VALID 12Z MON FEB 06 2023 - 12Z FRI FEB 10 2023
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST SUITE OF GUIDANCE CONTINUES TO HAVE MULTIPLE SOLUTIONS
TO HOW THIS PATTERN WILL EVOLVE THUS THE CONFIDENCE IN THIS
FORECAST REMAINS BELOW AVERAGE. THE INITIAL STARTING POINT OF THE
EXTENDED HAD FAIR AGREEMENT ON THE UPPER LEVEL PATTERN SO A MIX OF
DETERMINISTIC MODELS AND THE ENSEMBLE MEANS WERE USED BUT
TRANSITIONED HEAVILY TO THE MEANS BY THE START OF DAY 4 AND THEN
100 BLEND OF THE ENSEMBLE MEANS FOR THE REST OF THE EXTENDED
PERIOD.
TWO GENERAL FORECAST SCENARIOS SEEM TO EXIST IN GUIDANCE WITH
RECENT GFS/CANADIAN RUNS SHOWING RUN TO RUN STREAM SEPARATION
LEADING TO AN UPPER LOW CLOSING OFF IN THE SOUTHWEST/NORTHERN
MEXICO TUESDAY-WEDNESDAY THAT IS STRONGER THEN SLOWER TO EJECT
DOWNSTREAM THROUGH THE EAST-CENTRAL U.S. NEXT WEEK COMPARED TO THE
ECMWF/UKMET. ENSEMBLE MEMBERS BY AND LARGE SHOWED SIMILAR
PROGRESSION TRENDS AS THEIR PARENT MODELS WITH THE
GEFS/CANADIAN/NAEFS ENSEMBLE MEANS LESS PROGRESSIVE THAN THE ECMWF
ENSEMBLE MEAN. THIS REMAINS A DIFFICULT EMERGING SPLIT FLOW
FORECAST WITH LOW PREDICTABILITY, BUT STILL SUSPECT THAT A
SOLUTION ON THE LESS PROGRESSIVE SIDE OF THE FULL ENVELOPE OF
GUIDANCE MAKES MORE SENSE GIVEN MUCH GUIDANCE DOES DEVELOP A
SEPARATED SOUTHERN STREAM SYSTEM OF WHICH OFTEN ARE ON THE SLOW
SIDE TO EJECT.
..WEATHER/HAZARD HIGHLIGHTS
NEAR THE START OF THE WEEK A COUPLE ROUNDS OF LIGHT PRECIPITATION
WILL PASS OVER PORTIONS OF THE MIDWEST, GREAT LAKES AND THE
NORTHEAST REGION WITH SHORTWAVE PASSAGES AND THE APPROACH OF A
LEAD LOW/FRONTAL SYSTEM. THERE MAY BE LAKE ENHANCEMENT OF THE
SNOWFALL FOR THE FAVORED AREAS DOWNWIND OF THE GREAT LAKES WHICH
COULD RESULT IN HIGHER AMOUNTS THAN SURROUNDING LOCATIONS. SHOWERS
ARE POSSIBLE ALONG THE EASTERN SEABOARD WITH SOME MOISTURE RETURN
BY SUNDAY FROM FLORIDA INTO THE EASTERN CAROLINAS AND EASTERN
PARTS OF NEW ENGLAND, BUT ANY HEAVIER AMOUNTS LOOK TO REMAIN
OFFSHORE. MODERATE PRECIPITATION IS EXPECTED TO OVERSPREAD THE
WEST COAST AND INLAND TO THE INTERMOUNTAIN WEST AND ROCKIES REGION
EARLY BY NEXT WEEK. FOR MOST OF LOWER COASTAL AREAS THE
PRECIPITATION WILL LIKELY FALL AS RAIN AND THEN TRANSITION TO SNOW
FOR THE MID-BASE TO HIGHEST ELEVATIONS; WITH TYPICAL TERRAIN
ENHANCEMENT ACROSS THE COASTAL RANGES AND THE SIERRA NEVADA. AS
THE LOW PRESSURE SYSTEM ADVANCES EASTWARD THE PRECIPITATION AHEAD
OF IT COULD OVERSPREAD THE CENTRAL U.S. THE DETAILS OF THIS
PRECIPITATION INCLUDING PLACEMENT AND PRECIPITATION TYPE REMAIN
UNCERTAIN GIVEN THE MODEL DIFFERENCES. THE CURRENT FORECAST SHOWS
ENHANCED RAINFALL AMOUNTS CENTERED ACROSS THE SOUTHERN PLAINS AND
LOWER MISSISSIPPI VALLEY AND SURROUNDING AREAS BY
TUESDAY-WEDNESDAY WITH ENHANCED LOW/FRONTAL SYSTEM INDUCED RETURN
GULF OF MEXICO MOISTURE INFLOW. WPC HAS IDENTIFIED AN AREA ACROSS
THE SOUTHERN PLAINS AND PARTS OF THE LOWER MISSISSIPPI VALLEY AS
HAVING THE POTENTIAL FOR EXCESSIVE RAINFALL. AN EXPERIMENTAL
MARGINAL RISK IS IN EFFECT FOR THAT AREA TUESDAY INTO WEDNESDAY.
THE NORTHERN EDGE OF THE PRECIPITATION SHIELD HAS THE POTENTIAL
FOR SNOW/ICE ACROSS PORTIONS OF THE SOUTHERN PLAINS TO MIDWEST AND
INTERIOR NORTHEAST NEXT WEEK, BUT THIS IS SUBJECT TO CHANGE WITH
FUTURE FORECASTS. SUBSEQUENT EASTERN PACIFIC SYSTEM APPROACH
TUESDAY/WEDNESDAY SHOULD OFFER MODEST SYSTEM AMPLITUDE AND
ASSOCIATED MOISTURE/RAINFALL POTENTIAL ACROSS THE PACIFIC
NORTHWEST ALONG WITH TERRAIN/MOUNTAIN SNOWS INLAND FROM THE
NORTHWEST THROUGH THE NORTHERN GREAT BASIN/ROCKIES.
CAMPBELL/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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