009
FXUS02 KWBC 272036
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
335 PM EST FRI JAN 27 2023
VALID 12Z MON JAN 30 2023 - 12Z FRI FEB 03 2023
...DANGEROUSLY COLD TEMPERATURES AND WIND CHILLS ARE FORECAST
ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST THROUGH EARLY NEXT
WEEK...
..OVERVIEW
A MEAN TROUGH ALOFT FROM A HUDSON BAY CLOSED LOW THROUGH THE
SOUTHWESTERN U.S. EARLY IN THE WEEK SHOULD SHIFT SOMEWHAT TO THE
EAST BY THE LATTER PART OF THE WEEK AS THE HUDSON BAY LOW TRACKS
EASTWARD AND A SOUTHWESTERN U.S. SHORTWAVE/POSSIBLE EMBEDDED UPPER
LOW EJECTS OUT OF THE REGION. THE INITIAL PATTERN WILL LEAD TO
COLDER THAN AVERAGE TEMPERATURES THAT COULD BE MOST HAZARDOUS FOR
THE NORTH-CENTRAL U.S. DURING THE FIRST HALF OF THE WEEK.
MEANWHILE A RIDGE/UPPER HIGH OVER CUBA DURING MUCH OF NEXT WEEK
SHOULD KEEP THE SOUTHEAST WARMER THAN NORMAL. BETWEEN THESE
UPPER-LEVEL FEATURES AND TEMPERATURE REGIMES, EXPECT ACTIVE
WEATHER AS SHORTWAVE ENERGY AND THE COMBINATION OF A COUPLE WAVY
FRONTS ALONG WITH PERIODS OF GULF INFLOW SUPPORT A COUPLE OF
SIGNIFICANT PRECIPITATION EVENTS EAST OF THE ROCKIES WITH RAINFALL
TO THE SOUTH/SOUTHEAST AND WINTRY WEATHER IN THE COLDER AIR. SOME
LOCALLY ENHANCED RAIN AND HIGHER ELEVATION SNOW ARE POSSIBLE IN
THE SOUTHWEST EARLY IN THE WEEK WITH THE UPPER FEATURE CROSSING
THE REGION, WHILE THE WEST COAST MAY SEE INCREASING PRECIPITATION
CHANCES BY LATER NEXT WEEK WITH THE APPROACH OF AN EASTERN PACIFIC
UPPER TROUGH.
..GUIDANCE/PREDICTABILITY ASSESSMENT
REGARDING THE UPPER TROUGH DROPPING THROUGH THE SOUTHWESTERN U.S.
DURING THE FIRST HALF OF THE WEEK, LATEST MODELS AND ENSEMBLES
SEEM TO BE CONVERGING SOME COMPARED TO RECENT RUNS. OPERATIONAL
MODELS STILL GENERALLY SHOW A CLOSED LOW TRACKING DOWN THE
SOUTHERN CALIFORNIA COAST EARLY IN THE WEEK WITH THE OVERALL
SHORTWAVE PIVOTING EASTWARD THEREAFTER, THOUGH WITH A HINT OF
SLIGHTLY LESS FLOW SEPARATION THAN SOME SOLUTIONS HAD BEEN
SHOWING. AT THE SAME TIME THE ENSEMBLE MEANS DO NOT QUITE SHOW A
CLOSED LOW YET BUT HAVE BEEN TRENDING CLOSER TO THE OPERATIONAL
MODEL SCENARIO FOR EARLY NEXT WEEK. IN THE NEW 12Z CYCLE, THE CMC
STRAYS FROM THE MAJORITY AS IT DEPICTS A SLOWER/SOUTHWARD UPPER
LOW BY WEDNESDAY-THURSDAY. TIMING DIFFERENCES PERSIST FOR THE
EJECTION OF THIS FEATURE AS IT OPENS UP, WITH LATEST GFS RUNS
FASTER THAN ECMWF/CMC RUNS PER HISTORICAL TENDENCIES. POTENTIAL
FOR UPSTREAM SHORTWAVE ENERGY TO AFFECT THE EVOLUTION OF THIS
FEATURE BY MID-LATE WEEK ALSO COMPLICATES THE FORECAST. AN
OPERATIONAL MODEL COMPOSITE TRENDING TO A COMPROMISE BETWEEN
MODEL/ENSEMBLE IDEAS LATER IN THE PERIOD PROVIDES A REASONABLE
STARTING POINT AND DECENT CONTINUITY FOR DEPICTING THIS SYSTEM.
UPSTREAM THERE IS STILL A LOT OF MODEL AND ENSEMBLE
SPREAD/VARIABILITY FOR HOW APPROACHING PACIFIC TROUGH ENERGY MAY
ERODE THE RIDGE WHICH CONSENSUS SAYS WILL MOVE INTO THE WEST AFTER
MIDWEEK. OPTIONS RANGE FROM A PROGRESSIVE SHORTWAVE PER THE 00Z
CMC MEAN AND OPERATIONAL 12Z/26 ECMWF, TO A TROUGH OF VARYING
AMPLITUDE NEARING THE WEST COAST IN LATEST GFS/GEFS MEAN/CMC RUNS,
TO THE 00Z ECMWF KEEPING A STRONG RIDGE ALONG/OFFSHORE THE WEST
COAST (WITH THE ECMWF MEAN BETWEEN THE GFS CLUSTER AND 00Z ECMWF.
AT THE VERY LEAST THE 00Z ECMWF LOOKS EXTREME IN HOW IT PULLS OFF
ITS PACIFIC UPPER LOW, AND TELECONNECTIONS RELATIVE TO THE CORE OF
NEGATIVE HEIGHT ANOMALIES BETWEEN THE CANADIAN MARITIMES AND
GREENLAND OFFER SUPPORT FOR SOME SHORTWAVE ENERGY TO REACH THE
WEST COAST (PERHAPS A COMBINATION OF A DAY 7 SHORTWAVE AND ANOTHER
2-3 DAYS LATER). THUS HAVING AT LEAST WEAK SHORTWAVE ENERGY REACH
THE WEST COAST SEEMS REASONABLE AS A STARTING POINT WHILE WAITING
FOR ADDED CLUSTERING BEFORE SHIFTING TOWARD A MORE AMPLIFIED
TROUGH. THE NEW 12Z ECMWF HAS MADE PROGRESS IN ADJUSTING AWAY FROM
THE 00Z RUN.
FARTHER EAST THERE ARE STILL IMPORTANT DIFFERENCES IN THE HANDLING
OF NORTHERN PLAINS THROUGH NORTHEAST SHORTWAVE ENERGY, AFFECTING
THE POSITION OF SURFACE FRONT(S) AND HIGH PRESSURE TO THE NORTH.
AS HAS BEEN THE CASE FOR A NUMBER OF RUNS, THE GFS IS AN AMPLIFIED
AND FAST EXTREME WITH THIS SHORTWAVE, LEADING TO STRONGER HIGH
PRESSURE AND FARTHER SOUTH FRONTAL POSITION NEAR THE EAST COAST BY
DAY 5 WEDNESDAY. HOWEVER THERE HAS BEEN A MULTI-DAY TREND TOWARD A
MORE SUPPRESSED MIDWEEK PATTERN IN THE EAST SO THE GFS CANNOT BE
FULLY DISCOUNTED--AND IN FACT THE NEW 12Z ECMWF HAS ADJUSTED
CLOSER TO THE GFS SCENARIO. THE 00Z CMC WAS A PRONOUNCED EXCEPTION
TO THE OVERALL TREND WITH A WAVE TRACKING JUST SOUTH OF NEW
ENGLAND BUT THE NEW 12Z RUN DID ADJUST SOUTHWARD. CORRESPONDING TO
THE MASS FIELD TREND, PRECIPITATION FOR THE NORTHEAST HAS BEEN
TRENDING LIGHTER AND THE UPDATED FORECAST TRIED TO COMPROMISE
BETWEEN THE FAIRLY DRY OPERATIONAL MODEL TRENDS (AGAIN MINUS THE
00Z CMC) AND THE SEEMINGLY LAGGING ENSEMBLES THAT STILL HAD BROAD
COVERAGE.
BASED ON THE ABOVE CONSIDERATIONS, THE UPDATED FORECAST STARTED
WITH A 00Z/06Z OPERATIONAL MODEL BLEND EARLY IN THE PERIOD
FOLLOWED BY GRADUAL INCORPORATION OF THE 06Z GEFS/00Z ECMWF MEANS
WHILE PHASING OUT THE 00Z CMC AND REDUCING 06Z INPUT BY WEDNESDAY.
DUE TO WEST COAST FORECAST ISSUES, AFTER MIDWEEK THE BLEND
TRANSITIONED TO A SPLIT OF THE 00Z AND 12Z/26 RUNS FOR ECMWF INPUT
WHILE EVENTUALLY TILTING THE PROPORTION OF THE MEANS A LITTLE MORE
TO THE GEFS.
..WEATHER/HAZARD HIGHLIGHTS
VERY COLD CONDITIONS OVER THE NORTH-CENTRAL U.S. DURING THE
WEEKEND (NOW IN THE SHORT RANGE TIME FRAME) WILL CONTINUE INTO THE
NEXT WORK WEEK AS WELL, IN THE WAKE OF A STRONG COLD FRONT
PRODUCING A SURGE OF ARCTIC AIR. HIGHS IN THE SINGLE DIGITS AND
EVEN BELOW ZERO ARE POSSIBLE IN THE DAKOTAS INTO MINNESOTA WHILE
BITTERLY COLD LOWS COMBINED WITH WIND WILL PRODUCE DANGEROUS WIND
CHILLS. MUCH BELOW NORMAL TEMPERATURES SHOULD EXTEND ACROSS MUCH
OF THE CENTRAL U.S. THROUGH MIDWEEK ESPECIALLY, AS WELL AS ACROSS
MUCH OF THE INTERIOR WEST WITH TEMPERATURES 15-25F BELOW NORMAL
THROUGH MONDAY-TUESDAY WITH GRADUAL MODERATION THEREAFTER. A FEW
ISOLATED RECORD COLD HIGHS MAY BE POSSIBLE EARLY IN THE WEEK.
MEANWHILE THE FAR SOUTHEAST AND FLORIDA PENINSULA SHOULD SEE THE
MOST CONSISTENT ABOVE AVERAGE TEMPERATURES WITH HIGHS 10-15F ABOVE
AVERAGE AND PLUS 10-20F ANOMALIES FOR LOWS. A FEW RECORD HIGHS ARE
POSSIBLE MONDAY-WEDNESDAY. WHILE THE WESTERN/CENTRAL U.S.
MODERATES LATER IN THE WEEK, THE EAST WILL TREND SOMEWHAT COLDER
WITH NEW ENGLAND POSSIBLY SEEING HIGHS 10-20F BELOW NORMAL BY NEXT
FRIDAY.
THE POSSIBLE UPPER LOW EMBEDDED WITHIN THE CALIFORNIA/SOUTHWEST
UPPER TROUGH COULD PRODUCE SOME ENHANCED PRECIPITATION ACROSS
SOUTHERN CALIFORNIA CONTINUING INTO MONDAY AND ACROSS THE
SOUTHWEST MONDAY-TUESDAY. THEN THIS FEATURE AND THE OVERALL TROUGH
AND OTHER SHORTWAVES WILL PROVIDE SUPPORT FOR FRONTAL BOUNDARIES
WITH WAVES OF LOW PRESSURE THROUGH THE SOUTH-CENTRAL TO
SOUTHEASTERN U.S., WHICH COMBINED WITH GULF MOISTURE STREAMING IN
COULD LEAD TO MULTIPLE ROUNDS OF PRECIPITATION. ON THE SOUTHERN
SIDE LOCALLY HEAVY RAIN AND LOCALIZED FLOODING ARE POSSIBLE,
ESPECIALLY AT TIMES WHEN THERE IS SUFFICIENT INSTABILITY FOR
HIGHER RAIN RATES. WITH COLDER THAN NORMAL AIR IN PLACE ON THE
NORTHERN SIDE, WINTER WEATHER COULD ALSO BE A THREAT. A LEADING
NORTHERN STREAM WAVE MAY PRODUCE SOME SNOW OVER THE NORTHEAST ON
MONDAY. THEN THERE IS POTENTIAL FOR SNOW ACROSS PARTS OF THE
SOUTHERN HALF OF THE PLAINS AND MISSISSIPPI VALLEY INTO THE
OHIO/TENNESSEE VALLEYS AND THE MID-ATLANTIC AT TIMES, BUT WITH
FAIRLY LOW CONFIDENCE IN SPECIFICS SO FAR. THIS IS ALSO A PATTERN
THAT COULD SUPPORT FREEZING RAIN WITH ICE ACCUMULATIONS WITH THE
COLD AIR IN PLACE AT THE SURFACE AND POTENTIAL FOR WARM MOIST AIR
TO FLOW OVERTOP IT. THE PLACEMENT OF HEAVIEST RAIN, FREEZING RAIN,
AND SNOW ALL REMAIN IN QUESTION GIVEN SMALL-SCALE DETAILS LIKE
SURFACE FRONTAL POSITIONS AND LATE WEEK SHORTWAVE SPECIFICS REMAIN
UNCERTAIN. RECENT TRENDS HAVE BEEN FOR DRIER CONDITIONS OVER THE
NORTHEAST AFTER MONDAY, WHILE PERIODS OF LAKE EFFECT ARE POSSIBLE
TO THE LEE OF THE NORTHERN/EASTERN GREAT LAKES. THE WEST COAST MAY
START TO SEE SOME PRECIPITATION BY THE LATTER HALF OF THE WEEK BUT
WITH UNCERTAINTY OVER THE SOUTHWARD EXTENT AND AMOUNTS. CURRENTLY
THE BEST POTENTIAL FOR AT LEAST SOME RAIN/MOUNTAIN SNOW IS OVER
THE PACIFIC NORTHWEST WITH MOISTURE POSSIBLY EXTENDING AS FAR
SOUTH AS NORTHERN CALIFORNIA.
RAUSCH/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
HAZARDS:
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI
VALLEY, THE LOWER MISSISSIPPI
VALLEY, THE OHIO VALLEY, AND THE TENNESSEE VALLEY, TUE, JAN 31.
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHERN APPALACHIANS, THE
LOWER MISSISSIPPI VALLEY, THE
SOUTHERN PLAINS, AND THE TENNESSEE VALLEY, WED, FEB 1.
- HEAVY SNOW ACROSS PORTIONS OF THE CENTRAL ROCKIES, THE CENTRAL
GREAT BASIN, AND THE SOUTHWEST,
MON, JAN 30.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER
MISSISSIPPI VALLEY.
- FLOODING LIKELY ACROSS PORTIONS OF THE SOUTHEAST.
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE PLAINS,
THE CENTRAL GREAT BASIN, THE
NORTHERN/CENTRAL ROCKIES, MIDDLE MISSISSIPPI VALLEY, CALIFORNIA,
THE NORTHERN GREAT BASIN, AND THE
PACIFIC NORTHWEST, MON-WED, JAN 30-FEB 1.
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE
NORTHERN/CENTRAL PLAINS, THE UPPER/MIDDLE
MISSISSIPPI VALLEY, THE GREAT LAKES, AND THE OHIO VALLEY, MON-THU,
JAN 30-FEB 2.
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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