200
FXUS02 KWBC 151845
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT FRI MAR 15 2024
VALID 12Z MON MAR 18 2024 - 12Z FRI MAR 22 2024
..GENERAL OVERVIEW
IT REMAINS THE CASE THAT 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
GREAT LAKES/OHIO VALLEY REGION AND THE EAST, AND A REX BLOCK 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 MIDWEST/EAST SLOWLY LIFTS OUT SOME BY MIDWEEK, AND
THE SOUTHWEST UPPER LOW EVENTUALLY EVOLVES INTO AN OPEN WAVE AND
THEN EJECTS EASTWARD ACROSS THE SOUTHERN PLAINS/THE SOUTH GOING
INTO THURSDAY/FRIDAY. A MORE ZONAL FLOW PATTERN ALOFT IS LIKELY BY
MID- LATER NEXT WEEK, ALTHOUGH A DEVELOPING LOW PRESSURE SYSTEM
OVER THE SOUTH-CENTRAL U.S. WILL INCREASE THE PROSPECTS FOR SHOWERS
AND STORMS FOR THE SOUTHERN PLAINS/GULF COAST/THE SOUTH, WITH
POTENTIAL FOR WIDESPREAD ENHANCED RAINS/CONVECTION TO THEN WORK
DOWNSTREAM OVER THE SOUTHEAST AND TO START WORKING UP THE EAST
COAST IN ABOUT A WEEK TO BE DETERMINED.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE FROM THE 00/06 UTC CYCLE SEEMS REASONABLY WELL
CLUSTERED INTO MONDAY/EARLY TUESDAY AND A COMPOSITE SEEMS TO OFFER
A GOOD FORECAST BASIS ALONG WITH THE NATIONAL BLEND OF MODELS (NBM)
AND WPC CONTINUNITY. FORECAST SPREAD INCREASES MORE READILY FOR
THE REST OF NEXT WEEK, ESPECIALLY WITH THE HANDLING OF FEATURES
WORKING OVER THE EAST PACIFIC AND INTO THE WESTERN U.S. ALONG WITH
THE HANDLING OF THE LEAD SOUTHERN STREAM CLOSED LOW SLATED TO
STALL OVER THE SOUTHWEST AND SUBSEQUENT DOWNSTREAM PROGRESSION OF
THE WEATHER FOCUSING FEATURE. THE WPC MEDIUM RANGE PRODUCT SUITE
FOR THIS PERIOD WAS MAINLY DERIVED FROM A COMPOSITE OF GEFS/ECMWF
ENSEMBLE MEANS AND BEST MATCHING GUIDANCE FROM THE 06 UTC GFS/00
UTC ECMWF AND THE NBM. THIS SOLUTION MAINTAINS GOOD WPC CONTINUITY
AND IS IN LINE WITH A COMPOSITE OF THE LATEST 12 UTC CYCLE GUIDANCE.
..WEATHER/HAZARDS HIGHLIGHTS
AFTER MULTIPLE DAYS OF HEAVY RAINFALL IN THE SHORT RANGE FORECAST
PERIOD, THERE WILL LIKELY BE A WELCOMED ABATEMENT IN BOTH RAINFALL
COVERAGE AND INTENSITY GOING INTO EARLY NEXT WEEK. THE FRONT
CROSSING CENTRAL FLORIDA ON MONDAY WILL PROBABLY PRODUCE SOME
MODERATE TO LOCALLY HEAVY DOWNPOURS IN PLACES, BUT NOT ENOUGH TO
WARRANT ANY MARGINAL RISK AREAS AT THIS TIME. THE SAME HOLDS TRUE
FOR THE RIO GRANDE REGION OF SOUTHWESTERN TEXAS WITH SOUTHERLY FLOW
AHEAD OF THE EJECTING SOUTHWEST U.S. UPPER LOW WITH MAINLY LIGHT
TO MODERATE RAIN EXPECTED. AN EVEN QUIETER PATTERN IS LIKELY ON
TUESDAY FOR THE DAY 5 PERIOD WITH NO RISK AREAS NECESSARY.
TO THE NORTH, A SECONDARY COLD FRONT CROSSING THE GREAT
LAKES/NORTHEAST SHOULD BRING SOME GENERALLY LIGHT PRECIPITATION
ACROSS THE REGION. SUFFICIENT COLD AIR AND LOW LEVEL MOISTURE MAY
COMBINE TO PRODUCE SOME ACCUMULATING SNOWS FOR PORTIONS OF THE
CENTRAL APPALACHIANS AND DOWNSTREAM OF LAKE ERIE AND LAKE ONTARIO.
LOOKING AHEAD INTO MID-LATE NEXT WEEK, SHOWERS AND THUNDERSTORMS
WILL LIKELY INCREASE ACROSS THE SOUTH AS GULF MOISTURE ADVECTS
NORTHWARD AHEAD OF A DEVELOPING SURFACE LOW, WITH THE GREATEST
RAINFALL NEAR THE COAST AND OFFSHORE INTO THURSDAY, ESPECIALLY
ACROSS THE CENTRAL GULF COAST. THERE IS A GROWING GUIDANCE SIGNAL
THEN SUGGESTING POTENTIAL FOR WIDESPREAD ENHANCED RAINS/CONVECTION
TO THEN WORK DOWNSTREAM OVER THE SOUTHEAST AND TO START WORKING UP
THE EAST COAST IN ABOUT A WEEK.
MEANWHILE, THE EXPECTED UPPER FLOW TRANSITION INTO LATER NEXT WEEK
MAY ALSO LEAD INTO A MORE FAVORABLE PATTERN FOR ENERGY TO WORK
INCREASINGLY INTO THE NORTHWEST AND FARTHER INLAND TO THE NORTHERN
INTERMOUNTAIN WEST/ROCKIES. THIS WOULD INTRODUCE RENEWED SNOW
POTENTIAL ACROSS THE BROAD REGION AS ENHANCED LOCALLY BY TERRAIN.
TEMPERATURES FROM THE MIDWEST TO THE EAST COAST ARE FORECAST TO BE
5 TO 15 DEGREES BELOW AVERAGE ON MONDAY AND TUESDAY AS A CANADIAN
SURFACE HIGH WILL BE IN PLACE. THERE WILL LIKELY BE SOME FROST/FREEZE
CONCERNS FOR ANY AREAS WHERE SPRING GREEN-UP HAS STARTED AS
TEMPERATURES DIP WELL INTO THE 30S TO NEAR FREEZING, ESPECIALLY
TUESDAY MORNING. TEMPERATURES ACROSS THE SOUTHWEST WILL TREND
WARMER WITH TIME AS THE UPPER LOW WEAKENS, AND ABOVE NORMAL
TEMPERATURES EXPANDING OVER THE NORTHWEST EARLY IN THE WEEK WILL
MOVE INTO THE NORTHERN/CENTRAL PLAINS AND UPPER MIDWEST BY NEXT
WEDNESDAY, AND COLDER WEATHER ARRIVES TO MONTANA AND NORTH DAKOTA
BY THE END OF THE WEEK.
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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