786
FXUS02 KWBC 122026
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
425 PM EDT THU OCT 12 2023
VALID 12Z SUN OCT 15 2023 - 12Z THU OCT 19 2023
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
THERE REMAINS GOOD AGREEMENT IN THE LATEST 00Z/06Z MODEL GUIDANCE
FOR SUNDAY AND MONDAY ALLOWING FOR A PURELY DETERMINISTIC MODEL
BLEND AS A STARTING POINT FOR THE UPDATED WPC FORECAST PROGS
TODAY. BY TUESDAY/DAY 5, SOME DETAIL DIFFERENCES BEGIN TO EMERGE
AS ENERGY FROM AN INITIAL SHORTWAVE OVER THE MIDWEST CLOSES OFF
INTO AN UPPER LOW AS IT MOVES TOWARDS THE MID-ATLANTIC/SOUTHEAST.
THIS AFFECTS PLACEMENT OF A SURFACE LOW OFF THE EAST COAST, AND
ANY POTENTIAL RAINFALL IMPACTS FOR COASTAL REGIONS. OUT WEST,
TIMING OF THE NEXT SHORT WAVE INTO THE COAST BECOMES AN ISSUE AS
WELL AND EVEN MORE SO LATE NEXT WEEK AS THE TROUGH DEEPENS OVER
THE CENTRAL U.S.. THE WPC FORECAST FOR TODAY INCORPORATED
INCREASING AMOUNTS OF THE ENSEMBLE MEANS BY LATE IN THE PERIOD TO
MITIGATE THESE DIFFERENCES, WITH SOME CONTRIBUTION FROM
DETERMINISTIC SOLUTIONS AS WELL TO ALLOW FOR A LITTLE EXTRA
DETAIL/SYSTEM DEFINITION. THIS MAINTAINS GOOD CONTINUITY WITH THE
OVERNIGHT WPC FORECAST AS WELL, WITH ONLY INSIGNIFICANT CHANGES
NEEDED FOR TODAYS FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
A DYNAMIC UPPER TROUGH/CLOSED LOW AND DEEPENED SURFACE LOW/FRONTAL
SYSTEM WILL TRACK THROUGH THE MID-ATLANTIC THIS WEEKEND, LEADING
TO REFORMATION AS A COASTAL LOW/STORM AND MARITIME THREAT BY
SUNDAY. EXPECT SOME ENHANCED WINDS AND MOSTLY LIGHT WRAP-AROUND
PRECIPITATION TO EXIT THE EAST COAST AFTER SUNDAY. ADDITIONAL
ENERGY INTO THE UPPER LOW OVER THE MID-ATLANTIC/SOUTHEAST MAY
SPAWN ADDITIONAL CYCLOGENESIS OFF THE EAST COAST AROUND TUESDAY,
THOUGH RAINFALL IMPACTS FOR COASTAL LOCATIONS REMAIN HIGHLY
DEPENDENT ON PROXIMITY OF THE SYSTEM TO THE COAST AND ANY POSSIBLE
INTERACTIONS WITH ASSOCIATED INVERTED TROUGHING ACROSS THE
MID-ATLANTIC/NORTHEAST. MEANWHILE UPSTREAM, THE NEXT SHORTWAVE
SHOULD REACH THE COAST ON MONDAY, BRINGING MODERATE TO HEAVY
PRECIPITATION FOR THE NORTHWEST, FAVORING SOUTHERN FACING TERRAIN
OF THE PACIFIC NORTHWEST/OLYMPICS. HOWEVER, LOW ENOUGH
PRECIPITATION RATES DO NOT SEEM TO WARRANT AN EXCESSIVE RAINFALL
RISK AREA AT THIS TIME. MOISTURE SHOULD WORK ITS WAY INLAND
THROUGH THE MIDDLE OF NEXT WEEK, BUT GENERALLY REMAIN LIGHT AND
NON-HAZARDOUS. PRECIPITATION CHANCES MAY INCREASE AGAIN ACROSS THE
CENTRAL U.S./MIDWEST TOO AS THE TROUGH DEEPENS OVER THE CENTRAL
U.S. NEXT WEDNESDAY/THURSDAY.
THE COLD FRONT SWEEPING ACROSS THE EASTERN U.S. INTO SUNDAY WILL
BRING TEMPERATURES GENERALLY 10 TO 15 DEGREES BELOW NORMAL,
INCLUDING AS FAR AS SOUTH FLORIDA. MEANWHILE, A BUILDING RIDGE
OVER THE WEST-CENTRAL U.S. BRINGS TEMPERATURES GENERALLY 5 TO 10
DEGREES ABOVE NORMAL WEST FROM THE ROCKIES TO THE EASTERN LEE OF
THE CASCADES, WITH BRIEF MODERATION ON WEDNESDAY AS SHORTWAVE
ENERGY WORKS ITS WAY INLAND.
SANTORELLI/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
HAZARDS:
- FLOODING POSSIBLE ACROSS PORTIONS OF THE NORTHERN PLAINS.
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page