644
FXUS02 KWBC 291854
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
254 PM EDT FRI MAR 29 2024
VALID 12Z MON APR 01 2024 - 12Z FRI APR 05 2024
...A LOW PRESSURE/FRONTAL SYSTEM WILL SPREAD POTENTIALLY HEAVY
RAIN AND MOUNTAIN/NORTHERN TIER SNOW ACROSS THE CENTRAL TO EASTERN
U.S. NEXT WEEK AS AN ACTIVE NEW STORM DIGS INTO A COOLING WEST...
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE LARGE SCALE
FOR A VERY AMPLIFIED PATTERN DURING THE MEDIUM RANGE PERIOD. AN
ELONGATED TROUGH INTO THE CENTRAL U.S. EARLY WEEK MAY SHEAR WITH
SOME ENERGY HANGING BACK OVER NORTHERN MEXICO AND THE REST OF THE
ENERGY COMBINING WITH A NORTHERN STREAM SHORTWAVE INTO THE GREAT
LAKES TO PRODUCE A FAIRLY DEEP UPPER LOW THAT TRACKS ACROSS THE
OHIO VALLEY AND NORTHEAST NEXT WEDNESDAY-THURSDAY. THE GUIDANCE ALL
AGREES ON THIS SET-UP AND THE GENERAL TRACK BUT THERE REMAINS
NOTEABLE UNCERTAINTY ON THE SPEED OF THE UPPER LOW. THE
DETERMINISTIC AND ENSEMBLE MEAN SOLUTIONS SHOW A FAIRLY PROGRESSIVE
SYSTEM, BUT SOME OF THE EC-BASED ML/AI MODELS SUGGEST A
SLOWER/DEEPER LOW THROUGH THE OHIO VALLEY/NORTHEAST, AND THE
OVERALL TREND HAS BEEN TOWARDS A LITTLE BIT SLOWER/MORE SNOWY
SOLUTION FOR THE NORTHEAST.
MEANWHILE, THE NEXT AMPLIFIED SHORTWAVE SHOULD DROP INTO THE
NORTHWEST AROUND MID-WEEK AND LOTS OF UNCERTAINTY ON ITS EVOLUTION
AS WELL. THE GFS REMAINS AND OUTLIER WITH A DEEPER AND FARTHER
SOUND CUT-OFF UPPER LOW OVER THE SOUTHWEST LATE PERIOD, WHILE
ENSEMBLE MEANS/ECMWF SUGGEST AN AMPLIFIED SHORTWAVE OVER THE
NORTHWEST/GREAT BASIN. NEW 12Z CMC CAME IN WITH A FARTHER OFFSHORE
SOLUTION AS WELL, WHICH DOES HAVE SUPPORT FROM SOME OF THE LATEST
AI/ML MODELS AS WELL.
THE WPC FORECAST TODAY USED A BLEND OF THE LATEST DETERMINISTIC
SOLUTIONS DAYS 3-5 (MON-WED), INCREASING INCREMENTALLY THE ENSEMBLE
MEANS (WITH THE ECMWF) LATER IN THE PERIOD. OVERALL, THIS
MAINTAINED REASONABLE CONTINUITY WITH THE PREVIOUS FORECAST WHICH
GIVEN THE UNCERTAINTIES BOTH IN THE NORTHEAST AND THE WEST, IS THE
PREFERRED APPROACH FOR NOW.
..PATTERN OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
CLOSED UPPER TROUGHING WITH SEVERAL EMBEDDED LOWS WILL WORK INTO
THE FOUR CORNERS STATES AND NORTHWEST MEXICO INTO EARLY NEXT WEEK.
THIS FEATURE AND ITS SURFACE LOW PRESSURE SYSTEM WILL DIRECT
LINGERING MOISTURE INTO THE SOUTHWEST AND ROCKIES INTO MONDAY AND
PRODUCE TERRAIN ENHANCED RAIN AND HIGHER ELEVATION SNOW. SOME GUSTY
WIND POTENTIAL ON THE BACKSIDE OF THE SYSTEM ACROSS THE SOUTHERN
HIGH PLAINS AS WELL.
ASPECTS OF THESE UPPER/SURFACE FEATURES WILL EJECT DOWNSTREAM TO
INTERACT WITH INCREASINGLY DIGGING NORTHERN STREAM TROUGHING INTO
THE NORTH-CENTRAL U.S.. THIS SHOULD ACT TO CONSOLIDATE A MAIN
SURFACE LOW THAT SHOULD DEEPEN AND MOVE FROM THE CENTRAL PLAINS TO
THE NORTHEAST DURING THE WORKWEEK. EXPANSIVE PRECIPITATION COVERAGE
IS LIKELY WITH THIS LARGE SYSTEM, WITH SNOW AND FREEZING RAIN
POSSIBLE ON ITS NORTH SIDE, AND A HEAVY RAIN AND STRONG TO SEVERE
THUNDERSTORM FOCUS WITHIN AN UNSTABLE WARM SECTOR AND INTO THE LOW
AS MOISTURE POOLS ALONG THE SURFACE LOW'S FRONTS.
WELL BEHIND THIS SYSTEM, A STRONGLY AMPLIFYING UPPER TROUGH AND
LEADING AND WAVY COLD FRONT DIGGING INTO THE WEST SHOULD ACT TO
COOL TEMPERATURES AND SPREAD ENHANCED PRECIPITATION TO INCLUDE
INTERIOR AND TERRAIN/MOUNTAIN SNOWS SOUTHEASTWARD ACROSS THE WEST
INTO NEXT WEDNESDAY-FRIDAY IN INCREASINGLY UNSETTLED FLOW. DEPICTED
AREAS OF PRECIPITATION ARE CURRENTLY ON THE MODEST TO MODERATE SIDE
GIVEN TRACK/MOISTURE, BUT AMPLE UPPER SUPPORT AND FAVORED TERRAIN
LIFT MAY LEAD TO LOCALLY HEAVIER FOCUS AND ACTIVITY TO MONITOR. THE
WPC WINTER WEATHER OUTLOOK SHOWS THE GREATEST SNOW PROBABILITIES
OVER NORTHWEST TO NORTHERN INTERMOUNTAIN/ROCKIES TERRAIN/MOUNTAINS.
MEANWHILE, THE OHIO VALLEY WILL BE ONE AREA OF FOCUS FOR
POTENTIALLY HEAVY RAINFALL. SOME RAIN IS LIKELY THERE ON SUNDAY,
BUT AMOUNTS ARE FORECAST TO INCREASE BY MONDAY. A MARGINAL RISK
REMAINS IN PLACE FROM THE MIDDLE MISSISSIPPI VALLEY INTO THE OHIO
VALLEY ON MONDAY FOR THE WPC DAY 4 EXCESSIVE RAINFALL OUTLOOK
(ERO). MOISTURE AND INSTABILITY ARE ANOMALOUSLY HIGH FOR THIS TIME
OF YEAR, AND SHOWERS COULD TRAIN ALONG THE WEST TO EAST ORIENTED
WARM FRONT NEARBY. BY TUESDAY THE COLD FRONT AND LOW SHOULD
CONTINUE TO PUSH EAST AND THE HEAVIEST RAINFALL AT THAT POINT MAY
FOCUS OUT FROM THE TENNESSEE VALLEY AND INTO THE APPALACHIANS AND
PARTS OF THE MID-ATLANTIC WHERE A MARGINAL RISK ERO IS IN PLACE,
WITH LOWERED FLASH FLOOD GUIDANCE (FFG) VALUES ON THE NORTHERN END
AND GREATER INSTABILITY OVER SOUTHERN PORTIONS. ACCORDINGLY, THE
STORM PREDICTION CENTER IS MONITORING SEVERE POTENTIAL IN THE WARM
SECTOR FROM THE PLAINS TO JUST WEST OF THE APPALACHIANS FOR EARLY
NEXT WEEK TO MONITOR.
ON THE NORTHERN SIDE OF THE STORM SYSTEM, SNOW AND FREEZING RAIN
ARE POTENTIAL THREATS FROM THE UPPER MIDWEST AND GREAT LAKES
REGION MONDAY AND INTO PARTS OF THE NORTHEAST BY TUESDAY-WEDNESDAY
AND LINGERING INTO THURSDAY WITH CONTINUED WRAP- AROUND FLOW INTO
THE MAIN/WINDY LOW. THERE IS STILL CONSIDERABLE UNCERTAINTY IN THE
PLACEMENT AND AMOUNTS OF SNOW AND ICE, BUT THERE IS INCREASING
POTENTIAL FOR A SIGNIFICANT LATE SEASON STORM, SO CONTINUE TO
MONITOR FORECASTS. THE INTERIOR NORTHEAST MAY SEE THE HEAVIEST SNOW
AMOUNTS OVERALL BECAUSE OF THE DURATION OF THE POTENTIAL SNOW
EVENT THERE COMPARED TO THE NORTH- CENTRAL U.S./MIDWEST/GREAT
LAKES.
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
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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