632
FXUS02 KWBC 040645
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 AM EDT THU APR 4 2024
VALID 12Z SUN APR 07 2024 - 12Z THU APR 11 2024
...HEAVY RAIN AND FLASH FLOODING CONCERNS WILL INCREASE IN THE
SOUTHERN U.S. NEXT WEEK...
..PATTERN OVERVIEW
AN OMEGA STYLE FLOW PATTERN WILL BE UNCHARACTISTICALLY ON THE MOVE
OVER THE CONTINENTAL U.S. THIS WEEKEND INTO EARLY NEXT WEEK, WITH
A CLOSED UPPER TROUGH/LOW SLOWLY WORKING OFFSHORE FROM THE
NORTHEAST AND ANOTHER DEEP CLOSED TROUGH LOW EJECTING FROM THE
WEST TO THE PLAINS, SHUNTING AN AMPLIFIED/SANDWICHED CENTRAL NATION
UPPER RIDGE INTO THE EAST-CENTRAL U.S.. AS THE PLAINS LOW LIFTS,
IT WILL BE ACCOMPANIED BY A SURFACE FRONTAL SYSTEM THAT COULD BRING
A CHANCE OF SHOWERS TO PARTS OF THE CENTRAL U.S. AND THE OHIO,
TENNESSEE, AND LOWER MISSISSIPPI VALLEYS (THIS WILL LIKELY HAVE
IMPLICATIONS FOR ECLIPSE VIEWING ON MONDAY). ANOTHER UPPER LOW WILL
DIG DOWN THE WEST COAST INTO THE SOUTHWEST EARLY IN THE WEEK AND
MOVE INTO THE SOUTH-CENTRAL U.S. INTO NEXT MIDWEEK TO SUPPORT
CYCLOGENSIS/FRONTOGENESIS AND LEAD MOISTURE/INSTABILITY RETURN OVER
A DEVELOPING GULF COASTAL FRONT. THIS PATTERN WILL LIKELY PRODUCE
EXCESSIVE RAINFALL THAT COULD LEAD TO FLASH FLOODING IN THE
SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY AND VICINITY NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE REMAINS IN REASONABLY GOOD AGREEMENT ON THE WEATHER
PATTERN THROUGH THE MEDIUM RANGE PERIOD; HOWEVER, THERE IS STILL
AN EXPECTED AMOUNT OF SPREAD AND UNCERTAINTY LOCALLY FOR THIS TIME
RANGE. THE MAIN DIFFERENCES BETWEEN MODEL SOLUTIONS SURROUND THE
COMPLEX EVOLUTION OF THE FRONTAL SYSTEMS ACROSS THE CENTRAL U.S.
EARLY NEXT WEEK. THERE ARE DIFFERENCES IN HOW THE MODELS ARE
HANDLING THE EJECTION OF THE UPPER LOW TOWARDS THE UPPER MIDWEST,
WHICH WILL IN TURN AFFECT TIMING AND LOCATION OF FRONTS,
PRECIPITATION, AND CLOUD COVER.
THE WPC FORECAST WAS MAINLY DERIVED FROM A MULTI-MODEL BLEND OF
THE 18 UTC GFS AND 12 UTC ECMWF/UKMET/CMC FOR MAXIMUM SYSTEM
DETAIL THROUGH THIS WEEKEND INTO MONDAY. FOR TUESDAY-NEXT THURSDAY,
CANADIAN AND ECMWF ENSEMBLE MEANS WERE INCREASING RELIED UPON OVER
TIME TO SMOOTH OUT MODEL DIFFERENCES CONSISTENT WITH PREDICTABILITY.
THESE ENSEMBLE SYSTEMS ARE OVERALL LESS PROGRESSIVE WITH SYSTEMS
THAN THE GEFS AND THIS SOLUTION SEEMS A BETTER MATCH WITH MODELS AND
PATTERN AMPITUDE. LATEST 00 UTC GUIDANCE MAINTAINS THESE TRENDS.
..WEATHER/HAZARDS HIGHLIGHTS
A STRONG LOW PRESSURE SYSTEM IMPACTING THE NORTHEAST WILL MOVE
OFFSHORE THIS WEEKEND, BUT LIGHT TO LOCALLY MODERATE PRECIPITATION
MAY LINGER OVER NEW ENGLAND IN BRISK BACKSIDE FLOW.
MEANWHILE, UNSETTLED WEATHER WILL IMPACT THE PACIFIC NORTHWEST AND
NORTHERN AND CENTRAL ROCKIES THIS WEEKEND AS A COLD FRONT DROPS
SOUTH FROM CANADA AND A LOW PRESSURE SYSTEM STRENGTHENS OVER THE
PLAINS. HEAVY SNOW WILL BE POSSIBLE FOR PARTS OF THE NORTHERN
ROCKIES INTO SUNDAY, THEN CONDITIONS WILL IMPROVE AS THE SYSTEM
PROGRESSES EAST. EARLY NEXT WEEK, THIS SYSTEM WILL BRING A LARGE
SWATH OF SHOWERS AND THUNDERSTORMS (WITH SOME SEVERE THUNDERSTORMS
POSSIBLE) ACROSS THE PLAINS AND MISSISSIPPI VALLEY INTO THE
MIDWEST. THIS SYSTEM WILL BE RELATIVELY SLOW MOVING, WHICH COULD
RESULT IN LOCALLY HEAVY RAINFALL IN SOME AREAS. BEHIND THE SYSTEM,
HIGH WINDS WILL SPREAD FROM THE ROCKIES INTO THE PLAINS, WHICH WILL
COMBINE WITH DROPPING HUMIDITY TO PRODUCE A CRITICAL WILDFIRE RISK
OVER EASTERN NEW MEXICO, THE WESTERN HALF OF TEXAS, AND THE
OKLAHOMA PANHANDLE THIS WEEKEND.
UPSTREAM, A RENEWAL OF MAINLY LIGHT TO MODERATE PRECIPITATION IS
POSSIBLE ALONG THE WEST COAST EARLY NEXT WEEK AS A NEW PACIFIC
UPPER TROUGH/CLOSED LOW DIGS DOWN TOWARDS THE SOUTHWEST. THE FOCUS
FOR PRECIPITATION WILL THEN SHIFT TO THE SOUTH-CENTRAL U.S. TUESDAY
INTO WEDNESDAY, AND MOIST GULF INFLOW MAY BE RE-ENERGIZED AS A LOW
PRESSURE SYSTEM SWEEPS ACROSS THE SOUTHERN TIER OF THE NATION.
HEAVY RAINFALL SEEMS LIKELY ACROSS THE SOUTHERN PLAINS, LOWER
MISSISSIPPI VALLEY, AND MID-SOUTH, WHICH MAY LEAD TO FLASH FLOODING
CONCERNS.
TEMPERATURES WILL BE BELOW AVERAGE THIS WEEKEND INTO EARLY NEXT
WEEK ACROSS THE WESTERN U.S. AS UPPER LEVEL TROUGHING DOMINATES THE
WEATHER IN THIS REGION. TEMPERATURES FOR MUCH OF THE WEST SHOULD
REBOUND TO NEAR OR SLIGHTLY ABOVE AVERAGE BY TUESDAY, EXCEPT FOR IN
THE SOUTHWEST WHERE TEMPERATURES WILL REMAIN COOLER THAN AVERAGE.
IN THE CENTRAL U.S., TEMPERATURES SHOULD REMAIN NEAR TO SLIGHTLY
ABOVE AVERAGE WITH AREAS OF BELOW AVERAGE TEMPERATURES UNDER CLOUD
COVER AND PRECIPITATION. IN THE EAST, COLDER AIR WILL MOVE INTO THE
REGION BEHIND THE DEPARTING COASTAL LOW, WHICH WILL RESULT IN BELOW
NORMAL TEMPERATURES THIS WEEKEND. MORNING LOWS ARE FORECAST TO BE
NEAR FREEZING FROM THE NORTHEAST AND GREAT LAKES INTO THE MID-
MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, WHICH COULD AFFECT
SENSITIVE VEGETATION. A WARMING TREND SHOULD TAKE ROOT IN THE EAST
AND MIDWEST EARLY NEXT WEEK.
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 FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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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