228
FXUS02 KWBC 020700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 AM EST THU FEB 02 2023
VALID 12Z SUN FEB 05 2023 - 12Z THU FEB 09 2023
..OVERVIEW
THE MEDIUM RANGE PERIOD BEGINS SUNDAY WITH A WAVY AND FAIRLY
PROGRESSIVE UPPER-LEVEL PATTERN ACROSS THE LOWER 48. AN UPPER
TROUGH WILL SHIFT ACROSS THE CENTRAL AND EASTERN U.S. EARLY IN THE
WEEK BUT WITH FAIRLY DRY CONDITIONS, WHILE THE BIGGER WEATHER
MAKER LOOKS TO BE A TROUGH ENTERING THE WEST COAST SUNDAY
SPREADING SOME PRECIPITATION TO THE WEST. AS THAT TROUGH TRACKS
INTO THE CENTRAL U.S. IN SOME FASHION BY TUESDAY-WEDNESDAY, IT
SHOULD LEAD TO A WETTER PATTERN THERE. MUCH OF THE CENTRAL AND
EASTERN U.S. LOOKS TO SEE ABOVE AVERAGE TEMPERATURES THROUGH NEXT
WEEK, WITH NEAR NORMAL CONDITIONS IN THE WEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE EARLY PART OF THE MEDIUM RANGE PERIOD REMAINS IN REASONABLY
GOOD AGREEMENT AS ONE TROUGH TRACKS INTO THE EAST BY MONDAY,
ANOTHER STRONGER TROUGH DIGS INTO THE WEST, WITH RIDGING IN
BETWEEN. THE WPC FORECAST USED A BLEND OF THE 12/18Z DETERMINISTIC
GUIDANCE FOR DAYS 3-4 GIVEN NO NOTABLE OUTLIERS.
NOTABLY GREATER DIFFERENCES ARISE BY LATE MONDAY WITH THE WESTERN
TROUGH'S EVOLUTION. GFS RUNS HAVE BEEN PERSISTENT IN SHOWING
STREAM SEPARATION LEADING TO AN UPPER LOW CLOSING OFF IN THE
SOUTHWEST/NORTHERN MEXICO TUESDAY-WEDNESDAY AND SLOWING DOWN, WITH
SOME EJECTION EAST BY THURSDAY. THE 18Z RUN WAS EVEN FARTHER WEST
WITH THE UPPER LOW THAN THE 12Z RUN, AND THE NEWER 00Z RUN IS
CLOSE TO THE POSITION OF THE 12Z. ECMWF RUNS ON THE OTHER HAND
CONTINUE TO INDICATE A TROUGH WITH A BIT OF SEPARATION, BUT WITH
RELATIVELY MORE PHASING AND A STEADIER TREK EASTWARD. THE 12Z CMC
SEEMED SORT OF LIKE A COMPROMISE BETWEEN THE TWO--BUT THE NEWER
00Z RUN SHOWS MORE STREAM SEPARATION. UNFORTUNATELY ALL THE 12Z
ENSEMBLE SUITES APPEARED UNDERDISPERSIVE, WITH ENSEMBLE MEMBERS
GENERALLY CLUSTERING WITH THEIR OWN PARENT MODEL. THIS WAS
PARTICULARLY TRUE FOR THE GEFS, AS THE EC AND CMC ENSEMBLE MEMBERS
DID HAVE RELATIVELY MORE CROSSOVER WITH EACH OTHER IN CLUSTER
GROUPS. WHILE IT SEEMS REASONABLE TO HAVE SOME STREAM SEPARATION,
THE WPC FORECAST DID NOT FAVOR A SOLUTION AS SLOW AS THE GFS RUNS,
NOR AS FAST AS THE ECMWF WITH THE TRACK OF ITS TROUGH EAST.
ADDITIONAL ENERGY COMING IN NORTHWEST OF THE FEATURE CREATES
ADDITIONAL UNCERTAINTY WITH THE EVOLUTION AS WELL. THE FORECAST
BLEND QUICKLY TRANSITIONED TO FAVORING THE ENSEMBLE
MEANS--PARTICULARLY THE EC MEAN AND THE NAEFS MEAN AS A GOOD
COMPROMISE OF THE CMC/GEFS ENSEMBLES.
..WEATHER/HAZARD HIGHLIGHTS
A COUPLE OF ROUNDS OF LIGHT PRECIPITATION ARE FORECAST ACROSS THE
MIDWEST/GREAT LAKES INTO THE NORTHEAST NEXT WEEK, AND AMOUNTS
COULD BE ENHANCED DOWNWIND OF THE GREAT LAKES. SHOWERS ARE
POSSIBLE ALONG THE EASTERN SEABOARD WITH SOME MOISTURE RETURN BY
SUNDAY FROM FLORIDA INTO THE EASTERN CAROLINAS AND EASTERN PARTS
OF NEW ENGLAND, BUT ANY HEAVIER AMOUNTS LOOK TO REMAIN OFFSHORE.
IN THE WEST, GENERALLY MODERATE PRECIPITATION IS EXPECTED ON
SUNDAY IN THE FORM OF LOWER ELEVATION RAIN AND HIGHER ELEVATION
SNOW, WITH TYPICAL TERRAIN ENHANCEMENT ACROSS THE COASTAL RANGES
AND THE SIERRA NEVADA. SNOW IS ALSO FORECAST TO SPREAD INTO THE
INTERMOUNTAIN WEST AND ROCKIES EARLY NEXT WEEK, AND THEN
PRECIPITATION COULD OVERSPREAD THE CENTRAL U.S. BY MONDAY-TUESDAY
ALONG AND AHEAD OF A LOW PRESSURE/FRONTAL SYSTEM. THE DETAILS OF
THIS PRECIPITATION INCLUDING PLACEMENT AND PRECIPITATION TYPE
REMAIN UNCERTAIN GIVEN THE MODEL DIFFERENCES. THE CURRENT FORECAST
SHOWS ENHANCED RAINFALL AMOUNTS CENTERED ACROSS THE LOWER
MISSISSIPPI VALLEY AND SURROUNDING AREAS BY TUESDAY-WEDNESDAY,
WITH SOME POTENTIAL FOR WINTRY WEATHER ACROSS PORTIONS OF THE
PLAINS TO MIDWEST, BUT THIS IS SUBJECT TO CHANGE WITH FUTURE
FORECASTS. MEANWHILE, ADDITIONAL ROUNDS OF ENERGY COMING INTO THE
WEST WILL KEEP PRECIPITATION CHANCES LIKELY IN THE PACIFIC
NORTHWEST AND THE NORTHERN ROCKIES THROUGH MIDWEEK.
ANOTHER COLD MORNING IS EXPECTED SUNDAY ACROSS NORTHERN NEW
ENGLAND, BUT WITH TEMPERATURES BELOW ZERO MORE LIMITED IN SCOPE
THAN IN THE SHORT RANGE PERIOD, AND HIGHS SHOULD WARM UP CLOSE TO
NORMAL THERE DURING THE DAY. ACROSS THE CENTRAL U.S., THE AREAL
COVERAGE OF ABOVE AVERAGE TEMPERATURES BY 10-20F (15-25F ABOVE
AVERAGE FOR HIGHS) WILL CONTINUE TO GROW THROUGH EARLY NEXT WEEK,
WITH SOME SHIFT INTO THE EASTERN HALF OF THE U.S. BY
TUESDAY-THURSDAY. UNDERNEATH THE UPPER TROUGHING IN THE WEST,
HIGHS ARE FORECAST TO BE AROUND 5-10F BELOW NORMAL, THOUGH WITH
LOWS ABOUT AVERAGE.
TATE
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, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
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