351
FXUS02 KWBC 011817
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
117 PM EST FRI MAR 01 2024
VALID 12Z MON MAR 04 2024 - 12Z FRI MAR 08 2024
..WET PATTERN FOR PARTS OF THE WEST COAST AND THE SOUTH
..OVERVIEW
LATEST GUIDANCE FOR NEXT WEEK GENERALLY AGREES UPON LARGE SCALE
MEAN TROUGHING OVER THE WESTERN HALF OF THE LOWER 48 AND UPPER
RIDGING OFF THE EAST COAST. THIS PATTERN WILL FAVOR COOL
CONDITIONS OVER THE WEST WITH PERIODS OF ENHANCED PRECIPITATION
OVER SOME AREAS, WHILE ABOVE NORMAL TEMPERATURES PREVAIL FARTHER
EAST WITH THE LOWER MISSISSIPPI VALLEY INTO THE SOUTHEAST SEEING
THE BEST POTENTIAL FOR HEAVY RAINFALL. RAIN MAY EXTEND FARTHER
NORTH ACROSS THE EASTERN HALF OF THE COUNTRY AS WELL.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLES CONTINUE TO SHOW AGREEMENT FOR THE VERY LARGE
SCALE PATTERN, BUT STILL WITH SOME SIGNIFICANT EMBEDDED
DIFFERENCES THAT HAVE SENSIBLE WEATHER IMPACTS ACROSS SOME AREAS.
THERE ARE NOTABLY A LOT OF SHORTWAVE/TIMING DIFFERENCES ACROSS THE
NORTHERN TIER, THOUGH STILL WITH A GENERAL THEME OF ENOUGH
DYNAMICS EXISTING TO SUPPORT SOME DEGREE OF SURFACE FRONTAL
EVOLUTION. AT THE SAME TIME, A COUPLE OF PACIFIC SHORTWAVES SHOULD
AMPLIFY/MOVE INTO THE WEST AFTER MIDWEEK, WITH ANOTHER SURFACE
SYSTEM THAT MAY REACH THE PLAINS LATE NEXT WEEK. THE 06Z/12Z GFS
SEEMS TO BE THE BIGGEST OUTLIER FOR BOTH REGIONS, BUT ESPECIALLY
ACROSS THE WEST LATE WEEK. THE GFS IS MUCH QUICKER TO BRING A
SOUTHERN STREAM COMPACT UPPER LOW OFF THE CALIFORNIA COAST INLAND,
AND THE NEW 12Z RUN IS ESPECIALLY FAST/WEAKER WITH THIS. THE ECMWF
AND CMC SUPPORT A SLOWER PROGRESSION AND POSSIBLE EMBEDDED CLOSED
LOW OVER THE SOUTHWEST NEXT FRIDAY. ENSEMBLE MEANS ARE QUITE
MUTED/FLATTER BUT DO HAVE GENERAL POSITIONING CLOSER TO THE ECMWF
AND CMC. ALSO SOME DIFFERENCES LATE WEEK WITH A SHORTWAVE THROUGH
THE SOUTHEAST, WHICH DOES HAVE IMPLICATION FOR HEAVY RAINFALL
DISTRIBUTION AND TIMING FROM THE GULF COAST TO THE SOUTHEAST/EAST
COAST. THE WPC FORECAST WAS ABLE TO USE A DETERMINISTIC MODEL
BLEND FOR DAYS 3-4, BUT AFTER THAT INCORPORATED THE ENSEMBLE MEANS
IN PLACE OF THE GFS AND INCREASED ENSEMBLE MEAN CONTRIBUTION
AMIDST INCREASING FLOW DIFFERENCES NEXT THURSDAY-FRIDAY. THIS
APPROACH MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST
AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
DURING THE FIRST HALF OF THE WEEK EXPECT A FRONT LINGERING
OVER/NEAR THE GULF COAST TO PROVIDE A FOCUS FOR RAIN AND
THUNDERSTORMS THAT MAY EXTEND ALONG AND NORTH OF THE GULF COAST,
WITH A FRONT DROPPING SOUTHEASTWARD FROM THE CENTRAL U.S. ALSO
POSSIBLY ENHANCING GULF INFLOW SOMEWHAT TOWARD MIDWEEK. THE DAY 4
EXCESSIVE RAINFALL OUTLOOK VALID MONDAY REFLECTS A MARGINAL RISK
AREA CENTERED OVER THE LOWER MISSISSIPPI VALLEY WHILE THE DAY 5
MARGINAL RISK AREA REFLECTS THE CONSENSUS EASTWARD PROGRESSION OF
HEAVIEST RAINFALL POTENTIAL TOWARD THE SOUTHEAST (WHILE STILL
POSSIBLY LINGERING OVER THE CENTRAL GULF COAST REGION). EXPECT
SOME RAINFALL TO EXTEND FARTHER NORTH ALONG THE ADVANCING CENTRAL
U.S. FRONT AS WELL. FROM MIDWEEK ONWARD THE MID-ATLANTIC AND
NORTHEAST MAY BECOME THE MOST FAVORED REGION FOR MEANINGFUL
RAINFALL AS THE WAVY FRONT PROGRESSES EASTWARD. MEANWHILE, UPPER
LEVEL AND SURFACE SYSTEMS WILL PROMOTE EPISODES OF RAIN AND HIGHER
ELEVATION SNOW OVER THE WEST WITH GUIDANCE DIFFERENCES KEEPING
CONFIDENCE LOWER THAN DESIRED FOR THE DETAILS. THE NON-GFS
MAJORITY CLUSTER WOULD HAVE AN EARLY WEEK SYSTEM FOCUSING A NARROW
AXIS OF ENHANCED MOISTURE AIMED AT THE WEST COAST NEAR THE
CALIFORNIA/OREGON BORDER. THE ECMWF/ECENS MEAN STILL DEPICT FAIRLY
MODEST MOISTURE ANOMALIES WITH THIS EVENT WHOSE HEAVY RAINFALL MAY
BE FAIRLY LOCALIZED, SO HAVE OPTED NOT TO DEPICT ANY RISK AREA IN
THE DAY 4 ERO FOR NOW. A MID-LATE WEEK SYSTEM MAY BRING ADDITIONAL
RAIN/SNOW TO THE WEST. HOW QUICKLY THIS SYSTEM PROGRESSES THROUGH
THE WEST WILL DETERMINE WHETHER A REBOUND IN RAINFALL COULD OCCUR
ALONG/NORTH OF THE GULF COAST LATE IN THE WEEK.
UNDER THE INFLUENCE OF MEAN TROUGHING ALOFT, MOST AREAS FROM THE
WEST COAST INTO THE ROCKIES WILL SEE HIGHS 5-15F BELOW NORMAL
WHILE MORNING LOWS WILL TEND TO BE NEAR OR SLIGHTLY BELOW NORMAL.
IN CONTRAST, EXPECT WELL ABOVE NORMAL TEMPERATURES TO PREVAIL OVER
THE EASTERN HALF OR SO OF THE COUNTRY. PLUS 20-30F ANOMALIES WILL
BE POSSIBLE FROM THE CENTRAL-SOUTHERN PLAINS INTO THE NORTHEAST
EARLY-MID WEEK WITH LOCATIONS FROM THE MIDWEST INTO NORTHEAST
SEEING THE BEST POTENTIAL FOR SOME DAILY RECORDS.
SANTORELLI/RAUSCH
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY
MESSAGES ARE AT:
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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