310
FXUS02 KWBC 240637
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
236 AM EDT SUN SEP 24 2023
VALID 12Z WED SEP 27 2023 - 12Z SUN OCT 01 2023
..OVERVIEW
THE PATTERN THROUGH THE MIDDLE TO LATE PARTS OF NEXT WEEK FEATURES
AN AMPLIFYING UPPER TROUGH OVER THE WEST, INCREASINGLY AMPLIFIED
RIDGING WHICH EXPANDS FROM THE PLAINS THROUGH THE MIDWEST TOWARDS
THE APPALACHIANS WHICH ESCORTS A TROUGH EASTWARD INTO THE WESTERN
ATLANTIC.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THERE IS SOME INCREASED CONVERGENCE IN THE GUIDANCE WITH THE
WESTERN TROUGH, WITH THE CANADIAN SLOWLY BUT SURELY TRENDING
TOWARDS THE GFS/ECMWF/NAEFS/ECMWF ENSEMBLE MEAN SOLUTIONS, WHICH
INCREASES CONFIDENCE IN THE FORECAST SCENARIO. THE INITIAL BLEND
IS A FAIRLY EVEN BLEND OF THE 12Z ECMWF/UKMET/CANADIAN INTO FRIDAY
MORNING. THEREAFTER, THE BLEND INCREASINGLY RELIED ON THE 12Z
ECENS/12Z NAEFS MEANS. QPF GRIDS ARE FROM THE 01Z NBM ENHANCED
WITH THE ECMWF/GFS/CANADIAN THROUGH ABOUT DAY 5, AND THE ECMWF/GFS
THEREAFTER. THE REMAINDER OF THE GRIDS ARE PRIMARILY 01Z NBM
BASED, WITH ADJUSTMENTS TO THE POPS BASED ON THE RESULTANT QPF
BLEND.
..WEATHER/HAZARDS HIGHLIGHTS
AN EARLY SEASON STORM SYSTEM WILL BRING ACTIVE WEATHER TO THE
PACIFIC NORTHWEST THROUGH NEXT WEEK. ROUNDS OF HEAVIER
PRECIPITATION ARE EXPECTED. HOWEVER, GIVEN GENERALLY LOWER
RAINFALL RATES/TOTALS EXPECTED, NO EXCESSIVE RAINFALL AREAS
APPEARED NEEDED. SNOW AT HIGHER ELEVATION BECOMES INCREASINGLY
FAVORED WITH TIME ACROSS THE NORTHERN ROCKIES AS THE UPPER LEVEL
TROUGH STRENGTHENS.
A STALLED FRONT OVER THE FLORIDA PENINSULA THROUGH MUCH OF NEXT
WEEK WILL BRING PERIODIC HEAVY RAINS MID WEEK. THERE'S ENOUGH
AGREEMENT SIGNAL-WISE ON HEAVY RAINFALL IN AND NEAR PORTIONS OF
NORTHERN FL AND SOUTH GA TO INTRODUCE A MARGINAL RISK AREA FOR DAY
4/WEDNESDAY INTO THURSDAY MORNING. FOR THE FOLLOWING DAY, THE 00Z
ECMWF AND 00Z UKMET DEPART FROM THE OTHER GUIDANCE IN SHIFTING
HEAVY RAINFALL UP THE MID-ATLANTIC COAST. FOR NOW, NO RISK AREA
HAS BEEN DEPICTED FOR DAY 5/THURSDAY INTO FRIDAY MORNING.
INCREASED RIDGING OVER THE CENTER OF THE COUNTRY AND TROUGHING
FARTHER WEST, WILL MAKE FOR AN INCREASING TEMPERATURE TREND IN THE
PLAINS/GREAT LAKES AND DECREASING ACROSS THE WEST. BELOW NORMAL
TEMPERATURES OVER THE MID-ATLANTIC STATES CAN BE EXPECTED THROUGH
MIDWEEK BEFORE MODERATING ON APPROACH OF THE RIDGE.
ROTH/JACKSON
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 FORECAST, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY
MESSAGES 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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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