542
FXUS02 KWBC 080654
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
154 AM EST FRI MAR 08 2024
VALID 12Z MON MAR 11 2024 - 12Z FRI MAR 15 2024
...STRONG STORM EXITING THE NORTHEAST ON MONDAY WILL CONTINUE A
THREAT FOR HIGH WINDS...
...UNSETTLED WEATHER ALONG THE NORTHERN-CENTRAL WEST COAST WILL
CONTINUE INTO EARLY NEXT WEEK...
..OVERVIEW
STRONG LOW PRESSURE WILL BE EXITING THE NORTHEAST BY THE START OF
THE PERIOD ON MONDAY, BUT THE THREAT FOR HIGH WINDS WILL CONTINUE
ON THE BACKSIDE OF THIS SYSTEM AT LEAST THROUGH MONDAY. MEANWHILE,
A COUPLE OF SHORTWAVES WILL MOVE THROUGH THE WEST
MONDAY-WEDNESDAY, BRINGING SOME UNSETTLED CONDITIONS ACROSS MUCH
OF THE REGION BEFORE A STRONG UPPER RIDGE BUILDS OVER THE COAST
NEXT THURSDAY-FRIDAY. THIS SHOULD ALLOW FOR AMPLIFICATION OF THE
SYSTEM OVER THE WEST LATE WEEK, WITH GUIDANCE ALL SUGGESTING AN
EVENTUAL DEEP UPPER CLOSED LOW OVER THE SOUTHWEST/FOUR CORNERS.
THIS WOULD SUPPORT A POSSIBLY HEAVY RAINFALL THREAT BY NEXT
THURSDAY ACROSS PARTS OF SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY.
A MEAN UPPER RIDGE SHIFTING FROM THE CENTRAL TO EASTERN U.S. NEXT
WEEK WILL BRING AN EXPANDING AREA OF ABOVE NORMAL TEMPERATURES,
WITH THE GREATEST ANOMALIES LIKELY TO BE OVER THE NORTHERN
PLAINS/UPPER MIDWEST EARLY-MID WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST MODEL GUIDANCE SHOWS VERY GOOD AGREEMENT ON THE LARGE SCALE
PATTERN THROUGH THE ENTIRETY OF NEXT WEEK, AND A GENERAL BLEND OF
THE DETERMINISTIC GUIDANCE WORKED WELL FOR THE FIRST HALF OF THE
PERIOD. SOME TYPICAL DIFFERENCES IN THE DETAILS, MOST OF WHICH
WILL TAKE UNTIL THE SHORT RANGE PERIOD TO FULLY RESOLVE. GIVEN A
BRIEFLY QUIET PATTERN TO FOLLOW BEHIND A DEPARTING DEEP SURFACE
LOW FROM THE NORTHEAST ON MONDAY, THESE DIFFERENCES SHOULDN'T HAVE
HUGE IMPLICATIONS FOR SENSIBLE WEATHER IMPACTS ANYWAYS. AFTER
WEDNESDAY, THERE ARE SOME MORE NOTABLE DIFFERENCES WHICH ARISE
CONCERNING THE TIMING OF A NORTHERN STREAM SHORTWAVE WHICH
AMPLIFIES OVER THE GREAT LAKES LATE IN THE WEEK. AND WHILE
GUIDANCE IS IN EXCELLENT AGREEMENT ON A DEEP CLOSED LOW OVER THE
SOUTHWEST NEXT THURSDAY-FRIDAY, THERE ARE SOME SUBTLE DIFFERENCES
IN PLACEMENT OF THAT FEATURE AND THE RESULTING TRACK OF A SURFACE
LOW/FRONT THROUGH THE CENTRAL U.S TO MIDWEST, AND OF COURSE, LATE
PERIOD QPF DISTRIBUTION ACROSS THE SOUTH. A LOOK AT THE NEW 00Z
GUIDANCE (WHICH WAS AVAILABLE AFTER FORECAST GENERATION TIME)
SHOWS CONTINUED UNCERTAINTIES FOR BOTH THE NORTHERN AND SOUTHERN
STREAM SYSTEMS LATE NEXT WEEK. THE WPC BLEND INCORPORATED MORE OF
THE ENSEMBLE MEANS LATE PERIOD TO TONE DOWN THE DETAIL
DISCREPANCIES, BUT WAS STILL ABLE TO MAINTAIN 60 PERCENT
DETERMINISTIC GUIDANCE THROUGH DAY 7 ALLOWING FOR BETTER SYSTEM
DEFINITION OVERALL. NO MAJOR CHANGES WERE NEEDED TO THE NEW DAY 3
TO 6 PROGS AND QPF FORECAST COMPARED TO PREVIOUS WPC CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
AS THE STRONG SURFACE LOW EXITS THE NORTHEAST BY MONDAY, MUCH OF
THE PRECIPITATION WILL BE WELL OFFSHORE BY THEN, WITH THE
EXCEPTION OF SOME LIGHT TO MODERATE SNOW SHOWERS CONTINUING INTO
THE DAY ACROSS MAINE AND THE HIGHER TERRAIN ON THE BACKSIDE OF THE
LOW. GUSTY TO HIGH WINDS WILL ALSO CONTINUE INTO MONDAY AND MAYBE
TUESDAY ACROSS MUCH OF THE NORTHEAST. BEHIND THIS, WEATHER ACROSS
THE EASTERN AND CENTRAL U.S. SHOULD TREND QUIETER FOR THE FIRST
HALF OF THE WEEK, BUT THE WESTERN U.S. REMAINS UNSETTLED AS A
COUPLE OF SHORTWAVES BRING ROUNDS OF RAIN AND HIGHER ELEVATION
SNOW. THE DAY 4/MONDAY EXCESSIVE RAINFALL OUTLOOK HIGHLIGHTS A
MARGINAL RISK ALONG THE COAST FROM NORTHERN CALIFORNIA THROUGH
WASHINGTON. GUIDANCE CONTINUES TO SHOW SOME UNCERTAINTY FOR
DETAILS OF MAGNITUDE/DISTRIBUTION OF MOISTURE AND HIGHER RAIN
TOTALS, BUT WET GROUND CONDITIONS FOLLOWING HEAVY RAIN THE PRIOR
DAY (SUNDAY) MAY LOWER THE THRESHOLD FOR LOCALIZED RUNOFF ISSUES
IN SOME AREAS THAT SEE OVERLAPPING HEAVY RAIN/HIGH RATES.
AS THE FINAL UPPER SHORTWAVE IN THE SERIES AMPLIFIES AND MOVES
INLAND, THE BEST FOCUS FOR RAIN AND MOUNTAIN SNOW SHOULD SHIFT
INTO THE CENTRAL ROCKIES BY WEDNESDAY, WITH RAINFALL BEGINNING TO
INCREASE IN COVERAGE AND INTENSITY OVER THE PLAINS AND MISSISSIPPI
VALLEY AS WELL. MOISTURE STREAMING AHEAD OF A CLOSED LOW
DEVELOPING OVER THE SOUTHWEST SHOULD INCREASE THE THREAT FOR
ANOTHER ROUND OF HEAVY RAIN ACROSS THE LOWER MISSISSIPPI VALLEY
AND VICINITY NEXT THURSDAY SHIFTING MORE INTO THE GULF
COAST/SOUTHEAST BY NEXT FRIDAY. SOME THREAT FOR LOCALLY HEAVY
RAIN/MOUNTAIN SNOWS ACROSS THE SOUTHWEST AS WELL IN ASSOCIATION
WITH THAT SYSTEM.
MEAN RIDGING ALOFT OVER THE CENTRAL/EAST-CENTRAL U.S. WILL SUPPORT
AN EXPANDING AREA OF ABOVE NORMAL TEMPERATURES TO THE EAST OF THE
ROCKIES. THE CORE OF WARMEST ANOMALIES SHOULD COVER PARTS OF THE
NORTHERN PLAINS AND UPPER MIDWEST MONDAY THROUGH WEDNESDAY, WITH
HIGHS POTENTIALLY REACHING 20-30 DEGREES ABOVE NORMAL. ABOVE
NORMAL TEMPERATURES WILL GRADUALLY EXPAND INTO THE SOUTH AND EAST
MID TO LATER NEXT WEEK WEEK. OVER THE WEST, THE WET/SNOWY PATTERN
OVER NORTHERN-CENTRAL WEST COAST AND EVENTUALLY INTO THE ROCKIES
WILL MAINTAIN MODERATELY BELOW AVERAGE HIGHS AND NEAR/ABOVE
AVERAGE LOWS THROUGH EARLY NEXT WEEK. UPPER TROUGHING THAT
AMPLIFIES INLAND BY WEDNESDAY-THURSDAY SHOULD SPREAD A BROADER
AREA OF COOL DAYTIME HIGHS ACROSS THE WEST WITH TEMPERATURES
BEGINNING TO REBOUND AGAIN ALONG THE IMMEDIATE COAST NEXT FRIDAY
AS STRONG RIDGING BUILDS IN ALOFT.
SANTORELLI
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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