610
FXUS02 KWBC 162045
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
344 PM EST MON JAN 16 2023
VALID 12Z THU JAN 19 2023 - 12Z MON JAN 23 2023
...LATE WEEK SYSTEM LIKELY TO BRING MEANINGFUL SNOW TO NORTHERN
PARTS OF THE EAST, ESPECIALLY THURSDAY-THURSDAY NIGHT...
..OVERVIEW
MOST MODELS AND ENSEMBLES CONTINUE TO SHOW A LARGE SCALE MEAN
PATTERN THAT FEATURES A BUILDING EASTERN PACIFIC RIDGE AND
DOWNSTREAM POSITIVELY TILTED TROUGH. IN GENERAL THIS REGIME
SHOULD FAVOR EPISODES OF MOISTURE SPREADING THROUGH THE NORTHWEST
AND EAST/SOUTHEAST INTO THE ROCKIES (AND COOL TEMPERATURES OVER
MOST OF THE WEST) AS SHORTWAVES DROP INTO THE MEAN TROUGH, AS WELL
AS ABOVE AVERAGE RAINFALL CHANCES/TOTALS ACROSS THE SOUTHEAST.
INDIVIDUAL MODEL/ENSEMBLE SOLUTIONS VARY CONSIDERABLY FOR SOME
DETAILS WITHIN THIS PATTERN, SO CONFIDENCE IS MUCH LOWER FOR THE
SPECIFICS OF COVERAGE AND AMOUNTS OF PRECIPITATION WITHIN THE
FAVORED AREAS AS WELL AS FOR MOISTURE THAT COULD EXTEND INTO OTHER
AREAS AT TIMES. JUST AHEAD OF THE CHANGING MEAN PATTERN, A SYSTEM
WILL TRACK EAST-NORTHEAST FROM THE MIDWEST THURSDAY INTO FRIDAY
AND BRING SNOW TO NORTHERN AREAS ALONG WITH SOME RAIN FARTHER
SOUTH.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE SPREAD FOR THE LEADING NORTHEAST SYSTEM HAS BEEN FAIRLY
STABLE TO SLIGHTLY IMPROVING IN LATEST RUNS. RECENT GFS RUNS
(INCLUDING THE NEW 12Z RUN) HAVE HAD THE TENDENCY TO OPEN THE
UPPER LOW A BIT EARLIER THAN THE MODEL MAJORITY, LEADING TO A
CORRESPONDING EARLIER SHIFT OF EMPHASIS TO A LEADING LOW TRACKING
OFF THE EAST COAST FROM THE INITIAL PARENT LOW BY EARLY FRIDAY. A
GENERAL MODEL BLEND SHOULD TAKE CARE OF THESE RELATIVELY MINOR
DETAILS AT THIS TIME FRAME.
THE REMAINDER OF THE FORECAST PRIMARILY INVOLVES INITIAL SHORTWAVE
ENERGY DROPPING INTO THE WEST TO FORM A CLOSED LOW LIKELY TO TRACK
OVER THE FOUR CORNERS/SOUTHERN ROCKIES REGION AROUND
FRIDAY-SATURDAY, IF/HOW THIS FEATURE MAY INTERACT WITH NORTHERN
STREAM FLOW, AND THEN SIGNIFICANT DIFFERENCES IN THE CHARACTER OF
THE EASTERN PACIFIC RIDGE/SURROUNDING ENERGY THAT SHOULD DROP INTO
THE MEAN TROUGH--WITH INFLUENCE ON THE FIRST FEATURE. IN A BROAD
SENSE THE GUIDANCE CLUSTERS DECENTLY WITH THE LEADING WESTERN
FEATURE INTO SATURDAY, THOUGH WITH SOME RELATIVELY MINOR TIMING
DIFFERENCES. WITH TIME, RECENT CMC RUNS HAVE STRAYED SOMEWHAT TO
THE SLOW SIDE WHILE BUILDING MORE DOWNSTREAM RIDGING THAN OTHER
GUIDANCE. AFTER SATURDAY, THERE ARE SOME MORE SIGNIFICANT
DIFFERENCES WITH REGARDS TO INTERACTION WITH NORTHERN STREAM
ENERGY. RECENT GFS RUNS HAVE BEEN CONSISTENT WITH A STRONGER
SOUTHERN STREAM UPPER LOW WHILE THE ECMWF SUGGESTS EARLIER
INTERACTION/ELONGATION OF THE TROUGH. THE NEW 12Z GFS (AVAILABLE
AFTER FORECAST GENERATION TIME) DID TREND TOWARDS THE ECMWF THOUGH
BUT THIS TREND WILL NEED TO CONTINUE TO BE MONITORED. THIS WILL
HAVE IMPLICATIONS FOR EVENTUAL SURFACE EVOLUTION IN THE EASTERN
U.S. EARLY NEXT WEEK. THERE ARE STILL A LOT OF NOTABLE DIFFERENCES
WITH THE SECOND BIT OF ENERGY DROPPING INTO THE PACIFIC NORTHWEST
AS WELL WHICH COULD INFLUENCE EVOLUTION OF THE FIRST SYSTEM
EXITING THE ROCKIES AS WELL. RECENT RUNS HAVE TRENDED TOWARDS MORE
AMPLIFIED TROUGHING OVER THE WEST LATE PERIOD.
THE UPDATED FORECAST FOR TODAY STARTED WITH AN OPERATIONAL MODEL
COMPOSITE DAYS 3-5, EXCLUDING THE UKMET WHICH WAS EVEN SLOWER THAN
THE CMC WITH THE FIRST SOUTHWEST CLOSED UPPER LOW THURS-SAT. AFTER
THAT, INCREASED CONTRIBUTIONS FROM THE ENSEMBLE MEANS IN AN
ATTEMPT TO MIX OUT SOME OF THE HARDER TO RESOLVE DETAIL
DIFFERENCES LATE PERIOD. STILL WAS ABLE TO MAINTAIN 60 PERCENT 06Z
GFS/00Z ECMWF WITH 40 PERCENT ENSEMBLE MEANS. THIS APPROACH
MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST AS WELL.
..WEATHER/HAZARD HIGHLIGHTS
THE SYSTEM TRACKING FROM THE MIDWEST THROUGH THE NORTHEAST
THURSDAY INTO FRIDAY SHOULD BRING SOME MODEST SNOW TO AREAS FROM
THE CENTRAL/NORTHERN GREAT LAKES THROUGH NEW ENGLAND. EXPECT
RAINFALL TO THE SOUTH, WITH SOME LOCALLY MODERATE TO HEAVY POCKETS
OF RAINFALL POSSIBLE BUT LIKELY NOT REACHING THE POINT OF BEING
EXCESSIVE. WITH THE PATTERN CHANGE DEVELOPING FARTHER WEST, THE
NEXT AREA OF RAIN/MOUNTAIN SNOW CROSSING THE WEST LATE THIS WEEK
SHOULD BE ON THE MODERATE SIDE AND PROGRESS THROUGH THE INTERIOR
WEST/ROCKIES. AS THE SUPPORTING DYNAMICS EXTEND BEYOND THE
ROCKIES, EXPECT THE SOUTH TO SEE A REBOUND IN RAINFALL BY SATURDAY
AS A FRONT LINGERING OVER THE GULF LIFTS BACK NORTHWARD AHEAD OF
POSSIBLE DEVELOPING LOW PRESSURE. THIS POTENTIAL SYSTEM AND ITS
MOISTURE MAY SPREAD FARTHER NORTH OVER THE EASTERN U.S. THROUGH
THE WEEKEND AND THE START OF NEXT WEEK, WITH SOME WINTRY WEATHER
POSSIBLE OVER NORTHERN AREAS. CONFIDENCE REMAINS LOW FOR THE
DETAILS OF SURFACE EVOLUTION AND PRECIPITATION COVERAGE/AMOUNTS
OVER THE EAST IN THIS TIME FRAME. EXPECT ANOTHER FRONT TO SPREAD
SOME RAIN/MOUNTAIN SNOW INTO THE NORTHWEST AND THEN FARTHER
EAST/SOUTHEAST SATURDAY-MONDAY, BUT AGAIN WITH DECREASING
CONFIDENCE IN SPECIFICS.
THE PATTERN FROM LATE THIS WEEK INTO EARLY NEXT WEEK WILL FAVOR
PERSISTENTLY COOL DAYTIME HIGHS OVER MUCH OF THE WEST, ASIDE FROM
FAR NORTHERN AREAS AND THE PACIFIC NORTHWEST COAST, AND INTO PARTS
OF THE HIGH PLAINS. MOST LOCATIONS SHOULD SEE HIGHS OF 5-15F
BELOW NORMAL WITH SOME DAY-TO-DAY VARIABILITY WITH THE PROGRESSION
OF INDIVIDUAL FEATURES. ON THE OTHER HAND, THE EASTERN U.S. AND
NORTHERN TIER SHOULD BE ABOVE NORMAL ON MOST DAYS WITH SOMEWHAT
HIGHER ANOMALIES FOR MORNING LOWS RELATIVE TO DAYTIME HIGHS.
THURSDAY INTO EARLY FRIDAY WILL BE PARTICULARLY WARM OVER THE EAST
WITH SOME ANOMALIES EXCEEDING PLUS 20F AHEAD OF THE
MIDWEST/NORTHEAST SYSTEM. MOST OF ANY DAILY RECORDS SHOULD BE FOR
WARM LOWS, AT LEAST IF SUCH READINGS CAN HOLD ON THROUGH THE END
OF THE CALENDAR DAY.
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
HAZARDS:
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE LOWER
MISSISSIPPI VALLEY, THE SOUTHERN
APPALACHIANS, AND THE TENNESSEE VALLEY, SAT-SUN, JAN 21-JAN 22.
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE MID-ATLANTIC,
THE SOUTHERN APPALACHIANS, AND THE
TENNESSEE VALLEY, SUN, JAN 22.
- HEAVY SNOW ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND THE
NORTHERN GREAT BASIN, SAT, JAN 21.
- HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES AND THE
NORTHERN GREAT BASIN, SAT-SUN, JAN
21-JAN 22.
- HEAVY SNOW ACROSS PORTIONS OF THE NORTHEAST, THE GREAT LAKES,
AND THE UPPER MISSISSIPPI VALLEY,
THU, JAN 19.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE PACIFIC
NORTHWEST.
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PANHANDLE AND
MAINLAND ALASKA, THU-FRI, JAN
19-JAN 20.
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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