610
FXUS02 KWBC 071844
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
143 PM EST THU MAR 07 2024
VALID 12Z SUN MAR 10 2024 - 12Z THU MAR 14 2024
...STRONG STORM TO BRING RAIN/SNOW AND HIGH WINDS TO THE NORTHEAST
SUNDAY INTO MONDAY...
...UNSETTLED WEATHER ALONG THE NORTHERN-CENTRAL WEST COAST WILL
CONTINUE INTO EARLY NEXT WEEK...
..OVERVIEW
A STRONG LOW PRESSURE SYSTEM WILL CONSOLIDATE OVER THE NORTHEAST
LATE THIS WEEKEND INTO EARLY NEXT WEEK, BRINGING RAIN/SNOW AND
HIGH WINDS TO THE REGION ON SUNDAY AND MONDAY. ELSEWHERE, DRY
CONDITIONS WILL PREVAIL THROUGH EARLY NEXT WEEK FOR MUCH OF
NATION, WITH THE EXCEPTION OF SHOWERS ALONG A COLD FRONT IN
FLORIDA ON SUNDAY AND UNSETTLED WEATHER CONTINUING ALONG THE
NORTHERN AND CENTRAL WEST COAST. A SERIES OF UPPER-LEVEL
SHORTWAVES AND ACCOMPANYING SURFACE FRONTAL SYSTEMS WILL MOVE
ONSHORE THROUGH TUESDAY, WHICH MAY RESULT IN PERIODS OF HEAVY RAIN
AND HEAVY MOUNTAIN SNOW. SNOW WILL LIKELY EXTEND INLAND AS WELL,
REACHING THE NORTHERN ROCKIES. THE PATTERN SHOULD SHIFT WEDNESDAY
INTO THURSDAY AS THE FINAL SHORTWAVE IN THE SERIES PUSHES INLAND
AND THE UPPER TROUGH AMPLIFIES OVER THE WEST. PRECIPITATION WILL
TAPER OFF ALONG THE WEST COAST AS THE SURFACE FRONTAL SYSTEM
PUSHES ACROSS THE INTERMOUNTAIN WEST ON WEDNESDAY AND INTO THE
PLAINS BY THURSDAY. A MEAN UPPER RIDGE SETTING UP OVER THE
CENTRAL/EAST-CENTRAL U.S. WILL SUPPORT AN EXPANDING AREA OF ABOVE
NORMAL TEMPERATURES EAST OF THE ROCKIES, WITH THE GREATEST
ANOMALIES LIKELY TO BE OVER THE NORTHERN PLAINS/UPPER MIDWEST
EARLY-MID WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE SHOWS CONSISTENT AGREEMENT ON THE UPPER LEVEL
PATTERN LATE THIS WEEKEND INTO EARLY NEXT WEEK WITH A DEEP LOW
PRESSURE SYSTEM MOVING ACROSS THE NORTHEAST EARLY IN THE PERIOD
WHILE A SERIES OF SHORTWAVES MOVE INTO THE WEST. MODEL SOLUTIONS
BEGIN TO DIVERGE MORE MEANINGFULLY AFTER TUESDAY AS SHORTWAVE
ENERGY PROGRESSES THROUGH THE MEAN RIDGE IN THE CENTRAL AND
EASTERN U.S.. THE ECMWF AND THE CMC DETERMINISTIC SOLUTIONS CREATE
A CLOSED UPPER LOW NEAR THE GREAT LAKES WEDNESDAY WHILE THE GFS
SHOWS A WEAKER OPEN WAVE. THE POSITION OF THIS FEATURE HAS A
SIGNIFICANT AMOUNT OF UNCERTAINTY SURROUNDING IT, AND THEREFORE
THERE IS ALSO UNCERTAINTY IN THE POSITION AND STRENGTH OF
ASSOCIATED SURFACE FEATURES. MODELS ARE IN BETTER AGREEMENT ON THE
AMPLIFYING UPPER TROUGH AND CLOSED LOW DEVELOPING LATE IN THE
PERIOD OVER THE SOUTHWEST.
FOR THE AFTERNOON FORECAST UPDATE, A GENERAL DETERMINISTIC BLEND
OF THE ECMWF/GFS/CMC/UKMET WAS USED FOR THE FIRST HALF OF THE
FORECAST PERIOD AND THE GEFS/ECENS MEANS WERE ADDED WITH
INCREASING WEIGHT FOR THE SECOND HALF OF THE PERIOD. SLIGHTLY MORE
WEIGHT WAS GIVEN TO THE ECMWF OVER THE GFS TO BETTER RESOLVE THE
SHORTWAVE ENERGY MOVING THROUGH THE MEAN RIDGE MID-NEXT WEEK.
..WEATHER/HAZARDS HIGHLIGHTS
THE DAY 4 EXCESSIVE RAINFALL OUTLOOK (SUNDAY AND SUNDAY NIGHT)
HIGHLIGHTS A MARGINAL AREA OVER SOUTHERN NEW ENGLAND. THE STRONG
LOW PRESSURE SYSTEM MOVING ACROSS THE NORTHEAST WILL INITIALLY
HAVE TWO LOW PRESSURE CENTERS, BUT THE SOUTHERN LOW WILL BECOME
DOMINANT AS IS MOVES ALONG THE NEW ENGLAND COAST. STRONG ONSHORE
FLOW AHEAD OF THE ADVANCING LOW WILL SUPPORT HEAVY RAINFALL ACROSS
SOUTHERN NEW ENGLAND WHERE SOILS ARE SATURATED FROM RECENT
RAINFALL. PERIODS OF HEAVY SNOW WILL ALSO BE POSSIBLE IN NORTHERN
NEW ENGLAND AHEAD OF THE LOW, AND SNOW SHOWERS MAY CONTINUE ON
MONDAY AS MOISTURE AND COLD AIR WRAP AROUND THE BACKSIDE OF THE
SYSTEM. WINTER WEATHER OUTLOOK PROBABILITIES SHOW GREATER THAN A
50 PERCENT CHANCE FOR AT LEAST 0.25 OF AN INCH OF LIQUID IN THE
FORM OR SNOW OVER PORTIONS OF INTERIOR NEW ENGLAND ON SUNDAY. SOME
LAKE EFFECT/TERRAIN-ENHANCED SNOW SHOULD EXTEND FARTHER WESTWARD.
IN ADDITION TO HEAVY PRECIPITATION, THIS STORM WILL LIKELY CAUSE
HIGH WINDS ON SUNDAY AND MONDAY FOR PARTS OF THE MID-ATLANTIC AND
NORTHEAST.
IN ADDITION THE MARGINAL RISK AREA IN THE NORTHEAST, THE DAY 4
EXCESSIVE RAINFALL OUTLOOK SHOWS A SECOND MARGINAL RISK AREA OVER
THE NORTHERN AND CENTRAL WEST COAST, WHICH IS CONTINUED IN THE DAY
5 EXCESSIVE RAINFALL OUTLOOK AS WELL. THE RAPID SUCCESSION OF
FRONTAL SYSTEMS BRINGING MULTIPLE DAYS OF RAIN AND MOUNTAIN SNOW
TO THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA SHOULD ALREADY BE
IN PROGRESS AT THE START OF THE PERIOD EARLY SUNDAY AND ARE
FORECAST TO CONTINUE INTO TUESDAY. SOME OF THIS MOISTURE WILL
BRING SNOW INTO THE NORTHERN ROCKIES. GUIDANCE CONTINUES TO SHOW
SOME MIXED MESSAGES FOR DETAILS OF MAGNITUDE/DISTRIBUTION OF
MOISTURE AND RAINFALL TOTALS, BUT WET GROUND CONDITIONS SHOULD
LOWER THE THRESHOLD FOR LOCALIZED RUNOFF ISSUES WHERE THE
RELATIVELY HIGHER RAINFALL RATES OCCUR. AS THE FINAL UPPER TROUGH
IN THE SERIES AMPLIFIES AND MOVES INLAND, EXPECT THE BEST FOCUS
FOR RAIN AND MOUNTAIN SNOW TO SHIFT INTO THE CENTRAL ROCKIES BY
WEDNESDAY. THEN RAINFALL MAY INCREASE IN COVERAGE AND INTENSITY
OVER THE PLAINS BY NEXT THURSDAY.
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-NEXT 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 LOWS DECLINING TOWARD NORMAL.
DOLAN/RAUSCH
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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