919
FXUS02 KWBC 280700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 AM EST SAT JAN 28 2023
VALID 12Z TUE JAN 31 2023 - 12Z SAT FEB 04 2023
...NOTABLE PRECIPITATION LIKELY NEXT WEEK INCLUDING HEAVY RAIN IN
THE SOUTH-CENTRAL TO SOUTHEASTERN U.S. WITH FREEZING RAIN/SNOW ON
THE NORTHERN SIDE...
...DANGEROUSLY COLD TEMPERATURES AND WIND CHILLS ARE FORECAST
ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST AT TIMES THROUGH NEXT
WEEK...
..OVERVIEW
PERIODS OF TROUGHING ARE LIKELY THROUGH MUCH OF THE NORTHERN U.S.
NEXT WEEK EXTENDING FROM A PERSISTENT HUDSON BAY CLOSED LOW,
LEADING TO COLDER THAN AVERAGE TEMPERATURES FOR MUCH OF THE
NORTHERN TIER. THE COLD TEMPERATURES AND WIND CHILLS COULD BE MOST
HAZARDOUS FOR THE NORTH-CENTRAL U.S. DURING THE FIRST HALF OF THE
WEEK, WITH SIGNIFICANT COLD EXTENDING INTO THE NORTHEAST FOR THE
LATTER HALF OF NEXT 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 A SOUTHERN STREAM UPPER
TROUGH/LOW EJECTS FROM THE SOUTHWEST TUESDAY (WITH SOME RAIN AND
HIGHER ELEVATION SNOW THERE) AND TRACKS ACROSS THE
CENTRAL/SOUTHERN TIER OF THE CONUS. THIS COMBINED WITH A COUPLE
WAVY FRONTS ALONG WITH PERIODS OF GULF INFLOW WILL SUPPORT A
COUPLE OF SIGNIFICANT PRECIPITATION EVENTS WITH POSSIBLY HEAVY
RAIN TO THE SOUTH/SOUTHEAST AND WINTRY WEATHER IN THE COLDER AIR.
LATER IN THE WEEK, THE WEST COAST MAY SEE INCREASING PRECIPITATION
CHANCES WITH THE APPROACH OF AN EASTERN PACIFIC UPPER TROUGH.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE MAIN FEATURE OF NOTE AT THE BEGINNING OF THE MEDIUM RANGE
PERIOD TUESDAY WILL BE THE UPPER TROUGH WITH LIKELY AN EMBEDDED
CLOSED LOW TRACKING ACROSS THE SOUTHWEST AND EASTWARD THROUGH THE
PERIOD, SHOWING SOME DIFFERENCES IN TIMING AND PHASING WITH THE
NORTHERN STREAM TROUGH. THOUGH MODEL GUIDANCE IS IN BETTER
ALIGNMENT WITH TIMING THAN A DAY OR SO AGO WITH THIS FEATURE,
12/18Z MODEL RUNS STILL SHOWED A FASTER TRACK AND OPENING UP OF
THE TROUGH/LOW TO PHASE IN THE GFS COMPARED TO THE ECMWF AND CMC
RUNS, WHICH IS CONSISTENT WITH HISTORICAL TENDENCIES OF THE
MODELS. THE NEWER 00Z GFS DID SLOW A BIT WITH THE TRACK AND
PHASING AND LOOKS QUITE A BIT LIKE THE 00Z ECMWF NOW WITH THE
CENTROID OF THE UPPER LOW THROUGH DAY 5/THURSDAY, SO HOPEFULLY
MODELS WILL STAY CONSISTENT WITH THIS AGREEABLE POSITION.
DIFFERENCES WITH THIS FEATURE AND OTHER SHORTWAVES INCLUDING THOSE
IN THE NORTHERN STREAM CAUSE DIFFERENCES IN THE FRONTAL POSITIONS
ACROSS THE EASTERN TWO-THIRDS OF THE U.S., WHICH WOULD BE
IMPACTFUL WEATHER-WISE ESPECIALLY IN THE SOUTHERN-CENTRAL TIER
WHERE PRECIPITATION TYPES COULD DEPEND ON FRONTAL PLACEMENT.
UPSTREAM, WHILE OVERALL MODELS AGREE ON AN UPPER RIDGE OVER THE
WESTERN U.S. AROUND THURSDAY, THEY CONTINUE TO DIFFER WITH THE
AXIS OF ENERGY MOVING EAST THROUGH THE PACIFIC AND APPROACHING THE
WEST FOR THE LATTER PART OF THE WEEK TO PUSH THAT RIDGE EASTWARD.
THE PAST FEW ECMWF RUNS HAVE APPEARED TO BE OUTLIERS WITH BEING
SLOWER TO BRING IN THE PACIFIC TROUGH, THE NEWER 00Z RUN LOOKS
MORE IN LINE WITH THE CONSENSUS OF OTHER MODELS.
GIVEN THESE CONSIDERATIONS, THE WPC FORECAST FAVORED A MULTI-MODEL
DETERMINISTIC BLEND OF THE 12/18Z GUIDANCE EARLY IN THE PERIOD BUT
GRADUALLY TRANSITIONED TO ABOUT HALF MODELS/HALF GEFS AND EC
ENSEMBLE MEANS BY THE LATTER PART OF THE WEEK. THIS MAINTAINED
REASONABLY GOOD CONTINUITY WITH THE PREVIOUS FORECAST OTHER THAN
TYPICAL ADJUSTMENTS FOR NEWER GUIDANCE. THE MAIN CHANGES TO THE
NBM FOR QPF WERE TO BROADEN COVERAGE OF LIGHT AMOUNTS,
PARTICULARLY FOR LAKE EFFECT IMPACTED AREAS.
..WEATHER/HAZARD HIGHLIGHTS
THE UPPER TROUGH/LOW ATOP THE SOUTHWEST ON TUESDAY COULD PRODUCE
SOME RAIN AND HIGHER ELEVATION SNOW THERE LINGERING FROM THE SHORT
RANGE PERIOD. 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 IS EXPECTED, WHICH COULD CAUSE LOCALIZED FLOODING
ESPECIALLY AT TIMES WHEN THERE IS SUFFICIENT INSTABILITY FOR
HIGHER RAIN RATES. AT THIS TIME A SLIGHT RISK IS IN PLACE IN WPC'S
EXPERIMENTAL EXCESSIVE RAINFALL OUTLOOK FOR DAY 5/WEDNESDAY GIVEN
GOOD UPPER-LEVEL SUPPORT, NAMELY EXCELLENT DIFLUENCE/DIVERGENCE IN
THE RIGHT ENTRANCE REGION OF THE JET, AND SOMEWHAT WET ANTECEDENT
CONDITIONS. THEN ON THE NORTHERN SIDE OF THE PRECIPITATION
CHANCES, 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 LOW CONFIDENCE
CONTINUES IN THE SPECIFICS. 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 AS SMALL-SCALE DETAILS LIKE SURFACE
FRONTAL POSITIONS AND LATE WEEK SHORTWAVE SPECIFICS REMAIN
UNCERTAIN. ELSEWHERE, PERIODS OF LAKE EFFECT SNOW ARE POSSIBLE TO
THE LEE OF THE NORTHERN/EASTERN GREAT LAKES. SOME LIGHT
PRECIPITATION IS POSSIBLE IN THE NORTHWEST ON TUESDAY, BUT MORE
LIMITED TO WESTERN WASHINGTON BY WEDNESDAY. THE WEST COAST COULD
SEE INCREASING PRECIPITATION CHANCES 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.
VERY COLD CONDITIONS OVER THE NORTH-CENTRAL U.S. DURING THE SHORT
RANGE PERIOD WILL CONTINUE INTO NEXT WEEK, IN THE WAKE OF A STRONG
COLD FRONT PRODUCING A SURGE OF ARCTIC AIR. HIGHS IN THE SINGLE
DIGITS AND EVEN AT OR 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 TUESDAY WITH GRADUAL MODERATION
THEREAFTER. 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 TUESDAY-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.
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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