113
FXUS02 KWBC 092018
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
317 PM EST MON JAN 09 2023
VALID 12Z THU JAN 12 2023 - 12Z MON JAN 16 2023
...UNSETTLED AND ACTIVE PATTERN CONTINUES FOR WESTERN U.S. WITH
FOCUS ON CALIFORNIA ATMOSPHERIC RIVERS...
..OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
THE WEATHER PATTERN OVER THE CONUS LATER THIS WEEK THROUGH EARLY
NEXT WEEK WILL BE INCREASINGLY AMPLIFIED BUT PROGRESSIVE. AT THE
START OF THE PERIOD (THURSDAY), A STRONG RIDGE OF HIGH PRESSURE
WILL CONTINUE TO BUILD THROUGH THE INTERMOUNTAIN WEST WHILE
DOWNSTREAM OVER THE PLAINS, DIGGING SHORTWAVE ENERGY HELPS INDUCE
DEEPENING SURFACE LOW PRESSURE OVER THE MIDWEST. THE EASTERN U.S.
STORM SYSTEM WILL BRING WIDESPREAD PRECIPITATION AND SOME WEATHER
HAZARDS INCLUDING POTENTIAL FOR HEAVY RAINFALL AND SEVERE
THUNDERSTORMS TO PARTS OF THE SOUTHEAST. BACK TO THE WESTERN U.S.,
THE NEXT ATMOSPHERIC RIVER EVENT WILL BRUSH NORTHWEST CALIFORNIA
AND FOCUS MORE ON OREGON AND WASHINGTON. BY THIS WEEKEND INTO
EARLY NEXT WEEK, THE RIDGE OF HIGH PRESSURE MOVES EAST WHILE
ANOTHER ACTIVE AND POTENTIALLY STRONG ATMOSPHERIC RIVER AIMS AT
CALIFORNIA, BRINGING ANOTHER ROUND OF POTENTIALLY HEAVY
PRECIPITATION.
THROUGH THIS WEEKEND, THE LATEST MODEL GUIDANCE SHOWED FAIRLY
STRONG AND HIGH CONSISTENCY AND AGREEMENT WITH THE MAIN SYNOPTIC
FEATURES. THE MAIN QUESTION MARKS REMAIN ON ANY OFFSHORE LOW
PRESSURE DEVELOPMENT THIS WEEKEND OFF NEW ENGLAND. AS THE MAIN
SURFACE LOW LIFTS THROUGH THE GREAT LAKES AND OCCLUDES, MODELS
SUGGEST POTENTIAL SECONDARY LOW DEVELOPMENT ALONG THE COLD FRONT
ACROSS THE MID-ATLANTIC/NORTHEAST BEFORE THAT LOW BRUSHES NEW
ENGLAND. THIS MORE PHASED SCENARIO COULD SPELL ADDITIONAL
PRECIPITATION BACK ACROSS THE NORTHEAST AND POSSIBLY WINTER
PRECIPITATION FURTHER INLAND THIS WEEKEND. TODAY'S 12Z MODEL CYCLE
SUGGESTS A TREND TOWARD THIS IDEA. THIS SCENARIO BEARS WATCHING
FOR NAY POSSIBLE WINTER IMPACTS. OUTSIDE OF THIS SYSTEM AND
ELSEWHERE ACROSS THE CONUS, THE RELATIVELY GOOD AGREEMENT LED TO A
GENERAL MODEL BLEND OF THE LATEST GUIDANCE INCLUDING THE 00Z/06Z
ECMWF/GFS/UKMET/CMC AS WELL AS INCLUSION OF THE 00Z ECENS AND 06Z
GEFS MEANS ESPECIALLY BY DAY 6 AND DAY 7 GIVEN THE INCREASING
MODEL SPREAD. THIS LINES UP WELL WITH CONTINUITY AND THE LATEST
MODEL TRENDS.
..WEATHER/HAZARD HIGHLIGHTS
UNSETTLED AND ACTIVE WEATHER IS EXPECTED TO CONTINUE ACROSS
PORTIONS OF THE WEST AS A SERIES OF ATMOSPHERIC RIVERS MOVE
ONSHORE. THE HIGHLY AMPLIFIED PATTERN MENTIONED ABOVE WILL HELP
FOCUS THE BEST MOISTURE TRANSPORT AND RAINFALL ALONG THE IMMEDIATE
NORTHWEST CALIFORNIA COAST THURSDAY INTO FRIDAY, AND FURTHER UP
THE PACIFIC NORTHWEST COAST AFFECTING COASTAL REGIONS OF OREGON
AND WASHINGTON STATE. HOWEVER, BY THIS WEEKEND, ANOTHER STRONG
WEATHER SYSTEM APPROACHES CENTRAL CALIFORNIA AND WILL BRING
ANOTHER ROUND OF WIDESPREAD PRECIPITATION. THIS SYSTEM WILL IMPACT
A LARGER AREA OF CALIFORNIA WITH EVEN MORE HEAVY RAINFALL THREATS.
WORSENING FLOODING OR DELAYED IMPROVEMENT OF ONGOING IMPROVEMENT
IS POSSIBLE AGAIN ACROSS COASTAL CENTRAL TO SOUTHERN CALIFORNIA
WHILE THE HIGHER ELEVATIONS OF THE SERRA SEE HEAVY SNOWFALL. AS
THE ENERGY MOVES INLAND ON SUNDAY, RAIN AND HIGHER ELEVATION SNOWS
ARE POSSIBLE IN THE SOUTHWEST, AND EVENTUALLY RETURN FLOW OUT OF
THE GULF OF MEXICO MAY INCREASE PRECIPITATION CHANCES INTO THE
PLAINS/LOWER MISSISSIPPI VALLEY AS WELL.
MEANWHILE, BACK TO THE MIDWEST/EAST, A DEVELOPING AND DEEPENING
AREA OF LOW PRESSURE WILL SWEEP ACROSS THE REGION THURSDAY INTO
FRIDAY, BRINGING WIDESPREAD UNSETTLED WEATHER. A WARMER AIR MASS
IN PLACE WILL KEEP THE THREAT OF HEAVY SNOW OR ICE FAIRLY LIMITED,
EXCEPT FOR A POSSIBLE CHANGEOVER TO WINTRY PRECIPITATION ON THE
NORTHWEST SIDE OF THE LOW TRACK ACROSS THE GREAT LAKES REGION. ON
THE WARM SIDE OF THE SYSTEM, SOME LOCALLY HEAVY RAINFALL WILL BE
POSSIBLE THURSDAY INTO FRIDAY ACROSS PARTS OF THE SOUTHEAST
INCLUDING THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS. A SEVERE
THUNDERSTORM RISK IS ALSO POSSIBLE, AS ADVERTISED BY THE STORM
PREDICTION CENTER'S DAY 4 SEVERE WEATHER OUTLOOK, THURSDAY INTO
THURSDAY NIGHT ACROSS PORTIONS OF ALABAMA AND GEORGIA. AS THE
STORM SYSTEM MOVES TO THE EAST COAST, A SECONDARY AREA OF LOW
PRESSURE MAY DEVELOP JUST OFFSHORE NEW ENGLAND AND BRING
ADDITIONAL PRECIPITATION THREATS BUT THERE'S STILL SOME
UNCERTAINTY IN STORM TRACK AND POTENTIAL DEVELOPMENT THERE.
WITH THE MORE AMPLIFIED AND STORMY PATTERN ACROSS THE CONUS LATER
THIS WEEK AND THIS WEEKEND, MORE ANOMALOUS TEMPERATURE
FLUCTUATIONS ARE EXPECTED ACROSS THE CENTRAL TO EASTERN CONUS.
GENERALLY WARMER THAN NORMAL TEMPERATURES ARE EXPECTED EAST OF THE
ROCKIES THROUGH THE PERIOD, PARTICULARLY BY LATER THIS WEEKEND
INTO EARLY NEXT WEEK WHERE PARTS OF THE PLAINS COULD SEE HIGH
TEMPERATURES 15 TO 20 DEGREES F ABOVE NORMAL. EVEN MORE IMPRESSIVE
WILL BE THE VERY WARM NIGHTTIME LOWS, WITH READINGS 20 TO 25
DEGREES F ABOVE NORMAL FROM TEXAS THROUGH MINNESOTA SUNDAY AND
MONDAY.
SANTORELLI/TAYLOR
HAZARDS:
- HEAVY PRECIPITATION ACROSS PORTIONS OF NEW ENGLAND, THU-FRI, JAN
12-JAN 13.
- HEAVY RAIN ACROSS PORTIONS OF CALIFORNIA AND THE PACIFIC
NORTHWEST, THU-MON, JAN 12-JAN 16.
- HEAVY RAIN ACROSS PORTIONS OF THE PACIFIC NORTHWEST, THU-FRI,
JAN 12-JAN 13.
- HEAVY RAIN ACROSS PORTIONS OF CALIFORNIA, SAT, JAN 14.
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE SOUTHERN
APPALACHIANS, THE OHIO VALLEY, AND THE TENNESSEE VALLEY, THU, JAN
12.
- HEAVY SNOW ACROSS PORTIONS OF CALIFORNIA, SAT-MON, JAN 14-JAN 16.
- SEVERE WEATHER ACROSS PORTIONS OF THE SOUTHEAST, THE SOUTHERN
APPALACHIANS, AND THE TENNESSEE VALLEY, THU, JAN 12.
- FLOODING LIKELY ACROSS PORTIONS OF CALIFORNIA.
- HIGH WINDS ACROSS PORTIONS OF CALIFORNIA AND THE PACIFIC
NORTHWEST, THU, JAN 12.
- HIGH WINDS ACROSS PORTIONS OF THE SOUTHERN ROCKIES AND THE
SOUTHERN PLAINS, MON, JAN 16.
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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