570
FXUS02 KWBC 161859
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 PM EDT SAT MAR 16 2024
VALID 12Z TUE MAR 19 2024 - 12Z SAT MAR 23 2024
..GENERAL OVERVIEW
AN AMPLIFIED UPPER LEVEL PATTERN IS EXPECTED TO BE IN PLACE ACROSS
THE CONTINENTAL U.S. FOR THE BEGINNING OF NEXT WEEK, FEATURING A
DEEP UPPER TROUGH ACROSS THE EASTERN U.S., AND REX TYPE BLOCKING
OVER THE WESTERN U.S. WITH A CLOSED UPPER HIGH OVER THE PACIFIC
NORTHWEST AND A LOITERING UPPER LOW OVER THE DESERT SOUTHWEST. THE
TROUGH OVER THE EAST SLOWLY LIFTS OUT SOME BY MIDWEEK WITH MORE
BROAD CYCLONIC FLOW ALOFT. THE SOUTHWEST UPPER LOW EVOLVES INTO AN
OPEN WAVE AND THEN EJECTS EASTWARD ACROSS THE SOUTHERN PLAINS GOING
INTO THURSDAY, AND REACHING THE SOUTHEAST U.S. BY NEXT SATURDAY,
WITH A POTENTIAL COASTAL LOW DEVELOPMENT. UPPER RIDGE BREAKDOWN
OVER THE NORTHWEST WILL ALLOW FOR PACIFIC TROUGHING TO MOVE IN WITH
MORE WIDESPREAD RAIN AND MOUNTAIN SNOW BY FRIDAY AND INTO SATURDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL AND ENSEMBLE SOLUTIONS POINT TO SIMILAR WEATHER SCENARIOS
FOR TUESDAY AND WEDNESDAY, WITH A COMPOSITE OF BEST CLUSTERED
GUIDANCE FROM THE 06 UTC GFS AND 00 UTC ECMWF/CANADIAN OFFERING A
REASONABLE FORECAST BASIS AND DETAIL, MAINLY CONSISTENT WITH THE
NATIONAL BLEND OF MODELS AND WPC CONTINUITY. GROWING FORECAST
SPREAD CONTINGENT MAINLY UPON VARIANCES WITHIN NORTHERN STREAM FLOW
THROUGH CANADA, INTERACTION WITH EAST PACIFIC SYSTEMS AND THE
TIMING OF EJECTION OF SOUTHWEST U.S. UPPER TROUGH ENERGIES LATE
WEEK INTO NEXT WEEKEND PROMPTED PREFERENCE TO A COMPOSITE OF WELL
CLUSTERED GUIDANCE OF THE 06 UTC GEFS MEAN AND 00 UTC ECMWF/CANADIAN
ENSEMBLES MEANS THAT SEEM TO BEST HIGHTLIGHT SYSTEMS CONSISTENT
WITH PREDICTABILITY. THE 12 UTC CYCLE SUITE CONTINUES TO SUFFER
FROM MODEL-MODEL AND RUN-RUN ISSUES AT THESE TIME LONGER FRAMES.
..WEATHER/HAZARDS HIGHLIGHTS
A RELATIVELY BENIGN WEATHER PATTERN WILL BE IN PLACE OVER THE
LOWER 48 STATES TUESDAY INTO WEDNESDAY. HOWEVER, THERE WILL BE
MODEST ORGANIZED PRECIPITATION POTENTIAL FOR THE NORTHWEST, THE
SOUTHWEST/SOUTHERN PLAINS AND THE GREAT LAKES/NORTHEAST, MAINLY
GIVEN UPPER SUPPORT. IN THIS PATTERN, EXPECT SOME ACCUMULATING
SNOWS FOR FAVORED TERRAIN OF BOTH THE NORTHWEST AND SOUTHERN
ROCKIES, WHILE SUFFICIENT COLD FLOW WITH SECONDARY FRONTAL PASSAGE
MAY ALSO FAVOR PORTIONS OF THE NORTH-CENTRAL APPALACHIANS AND TO
THE LEE OF LAKE ERIE AND LAKE ONTARIO.
FOR IMPACTFUL TEMPERATURES, FROST/FREEZE CONCERNS ARE LIKELY
TUESDAY MORNING OVER PORTIONS OF THE SOUTH GIVEN THE SETTLING OF
POST-FRONTAL CANADIAN HIGH PRESSURE AND RADIATIONAL COOLING FOR
AREAS WHERE SPRING GREEN-UP HAS STARTED AS TEMPERATURES DIP 10-15
DEGRESS BELOW NORMAL THAT EQUATE TO MINIMUM TEMPERATURES RANGING
FROM WELL INTO THE 30S TO BELOW FREEZING.
LOOKING AHEAD TO THE END OF NEXT WEEK, SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO SIGNIFICANTLY INCREASE IN COVERAGE ACROSS THE
SOUTH/SOUTHEAST AS GULF MOISTURE ADVECTS INLAND AHEAD OF A
DEVELOPING SURFACE LOW. WHILE LATEST MODEL TRENDS SHOW THE
GREATEST RAINFALL JUST OFFSHORE OVER THE NORTHERN GULF, THERE IS A
SIGNAL FOR SOME HEAVY AMOUNTS INLAND FROM TEXAS THROUGH THE GULF
COAST INTO FLORIDA. THERE IS AN INCREASING MODEL SIGNAL FOR A
POTENTIAL COASTAL LOW TO DEVELOP OFFSHORE THE SOUTHEAST HEADING
INTO NEXT SATURDAY AS THE GULF LOW CROSSES FLORIDA, AND IF THIS
COMES TO PASS, HEAVY RAIN AND GUSTY WINDS COULD DEVELOP FOR AT
LEAST THE COASTAL CAROLINAS, WITH GUIDANCE STILL QUITE VARIED ON
THE INLAND EXTENT AND NORTHWARD COASTAL LOW INFLUENCE NEXT WEEKEND.
MEANWHILE WELL UPSTREAM, UPPER RIDGE BREAKDOWN DOWN OVER THE
NORTHWESTERN U.S. SHOULD EVENTUALLY ALLOW PACIFIC UPPER TROUGHING
TO WORK INLAND TO SUPPORT A RETURN TO A PATTERN WITH MORE
WIDESPREAD RAINS AND INLAND/MOUNTAIN SNOWS INTO FRIDAY AND
SATURDAY, BUT GUIDANCE REMAINS VARIED WITH EVENTUAL FLOW EVOLUTION.
HAMRICK/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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