303
FXUS02 KWBC 041903
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 PM 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 UNCHARACTERISTICALLY PROGRESSIVE OMEGA FLOW PATTERN WILL BE IN
PLACE OVER THE LOWER 48 THROUGH MIDDLE OF NEXT WEEK. THE LEADING
TROUGH WILL BE PULLING OFFSHORE THE NORTHEAST WITH A NARROW AREA OF
WEAK RIDGING AND A BROAD TROUGH/UPPER LOW EJECTING FROM THE WEST
INTO THE PLAINS. 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 ENVIRONMENT AND PATTERN WILL LIKELY BE
CONDUCIVE FOR SCATTERED TO WIDESPREAD HEAVY RAIN TO DEVELOP ACROSS
THE LOWER MISSISSIPPI VALLEY AND GULF STATES RESULTING IN EXCESSIVE
RAINFALL OVER A MULTI-DAY PERIOD.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST RUNS OF GLOBAL AND ENSEMBLE GUIDANCE HAVE VERY GOOD
CLUSTERING THROUGH MUCH OF THE EXTENDED PERIOD THAT RESULTS IN
ABOVE AVERAGE CONFIDENCE, ESPECIALLY WITH THE PATTERN EVOLUTION
ACROSS THE PLAINS/MISSISSIPPI VALLEY. 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 STARTING WITH HOW/WHERE THE UPPER LOW EJECTS TOWARD
THE UPPER MIDWEST. THESE DIFFERENCES WILL AFFECT THE TIMING AND
PLACEMENT OF THE FRONTS AND THE ASSOCIATED CLOUD COVER AND
PRECIPITATION.
IN A SIMILAR APPROACH TO THE PREVIOUS FORECAST, THE WPC SUITE OF
PRODUCTS UTILIZED A MULTI MODEL APPROACH BY USING THE 06Z GFS AND
THE 00Z ECMWF/UKMET/CMC THROUGH MONDAY. FOR TUESDAY AND BEYOND THE
UKMET WAS DROPPED WHILE THE INCLUSION AND WEIGHTING OF THE
CANADIAN AND EC ENSEMBLE MEANS WHERE INCREASED. THE EC AND CMC
SOLUTIONS, PARTICULARLY FOR QPF FOR THE SOUTHERN TIER STATES, ARE A
BIT WETTER AND REFLECT THE CLIMATOLOGY THAT THIS PATTERN TYPICALLY
BRINGS.
..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. THIS WILL USHER IN SNOW/HEAVY SNOW FOR PORTIONS OF THE
NORTHERN ROCKIES INTO SUNDAY BEFORE IMPROVING FOR THE START OF THE
WEEK AS THE SYSTEM ADVANCES EASTWARD. A LARGE SWATH OF SHOWERS AND
THUNDERSTORMS WILL ACCOMPANY THIS FRONT AS IT MOVES THROUGH THE
CENTRAL U.S. SOME OF THESE STORMS THAT DEVELOP OVER THE PLAINS,
MISSISSIPPI VALLEY AND MIDWEST ARE EXPECTED TO BE SEVERE. 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.
MUCH OF THE WEST WILL HAVE BELOW AVERAGE TEMPERATURES THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEKS THANKS FOR THE BROAD TROUGH AND
UPPER LOWS TRACKING THROUGH. 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.
CAMPBELL/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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