853
FXUS02 KWBC 141811
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
110 PM EST SAT JAN 14 2023
VALID 12Z TUE JAN 17 2023 - 12Z SAT JAN 21 2023
...ACTIVE PATTERN CONTINUES FOR THE WEST AND OTHER PARTS OF THE
LOWER 48 BUT WITH CENTRAL/SOUTHERN CALIFORNIA TRENDING DRIER
MID-LATE WEEK...
..OVERVIEW
THE MODELS AND ENSEMBLES CONTINUE TO SHOW AN INITIAL PATTERN
FEATURING A SEQUENCE OF PACIFIC SYSTEMS TRACKING INTO THE WEST AND
THEN NORTHEASTWARD BEYOND THE ROCKIES FOLLOWED BY A TRANSITION
TOWARD A BUILDING EASTERN PACIFIC UPPER RIDGE THAT WOULD LEAD TO
MEAN UPPER TROUGHING OVER THE INTERIOR LOWER 48, ALBEIT WITH SOME
UNCERTAINTY OVER THE CHARACTER OF THE TROUGH. THIS EVOLUTION WILL
LIKELY BEGIN A PERIOD OF DRIER WEATHER TO CENTRAL-SOUTHERN
CALIFORNIA AFTER MONDAY AND THEN THE REST OF THE STATE AFTER
ANOTHER SYSTEM BRINGS SOME RAIN/MOUNTAIN SNOW TO THE PACIFIC
NORTHWEST/NORTHERN CALIFORNIA AROUND MIDWEEK. THE CLIMATE
PREDICTION CENTER'S 8-14 DAY OUTLOOK CONTINUES TO SUGGEST THAT THE
DRIER PATTERN FOR CALIFORNIA WILL EXTEND BEYOND THE MEDIUM RANGE
PERIOD. THE DOMINANT SYSTEM OF INTEREST NEXT WEEK WILL CROSS THE
WEST WITH RAIN AND MOUNTAIN SNOW DURING THE FIRST HALF OF NEXT
WEEK AND SHOULD SPREAD A BROAD AREA OF SIGNIFICANT WEATHER ACROSS
PORTIONS OF THE CENTRAL-EASTERN U.S. WEDNESDAY-FRIDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE SUITE OF 00Z AND 06Z GUIDANCE APPEAR TO CAPTURE THE OVERALL
SYNOPTIC PATTERN OVER THE LOWER 48 REASONABLY WELL DURING THE
MEDIUM RANGE PERIOD. SOME FINER DETAILS STILL NEED TO BE RESOLVED
WITH RESPECT TO THE EVOLUTION OF THE SECOND UPPER TROUGH. A
GENERAL MODEL BLEND CONSISTING OF THE 00Z EC/CMC/UKMET AND 06Z GFS
WERE USED THROUGH DAY 5. THE 00Z UK WAS AN OUTLIER IN ITS HANDLING
OF THE FIRST WESTERN TROUGH AXIS SO IT CARRIED LESS WEIGHT IN THE
BLEND THROUGH DAY 5. ENSEMBLES, WITH WEIGHTING TOWARD THE 00Z ECE,
WERE INTRODUCED ON DAY 5 AND INCREASED IN PROMINENCE THROUGH DAY
7. THE 06Z GFS APPEARS TO STRENGTHEN, COMPARED TO THE PAST SEVERAL
RUNS, THE UPPER TROUGH EMERGING FROM THE WEST ON DAY 4 WHILE THE
00Z EC APPEARS TO WEAKEN IT. THE 00Z GFS WAS INCLUDED ON DAY 4 DUE
TO ITS AGREEMENT WITH THIS TROUGH FEATURE WITH THE REST OF THE
DETERMINISTIC GUIDANCE. THERE'S REASONABLE MODEL AGREEMENT WITH
THE TROUGH ORIENTATION OF NEXT WEEK'S DAY 6 DYNAMIC STORM WITH
TRENDS SHIFTING TOWARD A DEEPER/MORE POTENT UPPER TROUGH SOLUTION
THAN WHAT WAS PREVIOUSLY FORECAST. THE 06Z GEFS AND 00Z ECE MEANS
WERE IN REASONABLE AGREEMENT REGARDING THIS SYSTEM WHICH IS WHY
THEY CARRIED MORE WEIGHT IN OUR BLEND.
..WEATHER/HAZARD HIGHLIGHTS
THE SYSTEM MOVING THROUGH THE WEST ON TUESDAY SHOULD BRING RAIN
AND HIGHER ELEVATION SNOW ACROSS THE FOUR CORNERS STATES. THEN
EXPECT THIS SYSTEM TO BRING A VARIETY OF WEATHER TO THE CENTRAL
AND EASTERN U.S. MID-LATE WEEK. THIS INCLUDES THE POTENTIAL FOR
HEAVY RAINFALL OVER AND NEAR THE LOWER HALF OF THE MISSISSIPPI
VALLEY, TENNESSEE VALLEY, AND LOWER OHIO VALLEY. THE UPPER
DYNAMICS/LOW LEVEL GULF INFLOW AND GUIDANCE SIGNALS APPEAR
SUFFICIENTLY FAVORABLE TO DEPICT A SLIGHT RISK AREA ON THE DAY 5
EXPERIMENTAL EXCESSIVE RAINFALL OUTLOOK VALID 12Z WEDNESDAY-12Z
THURSDAY. SOME LOCALLY MODERATE TO HEAVY RAINFALL MAY EXTEND
FARTHER THROUGH THE EAST THEREAFTER BUT WITH LOWER CONFIDENCE IN
DETAILS. MEANINGFUL WINTRY WEATHER WILL BE POSSIBLE IN THE COLD
SECTOR, CURRENTLY MOST LIKELY ALONG AN AXIS FROM THE CENTRAL
PLAINS THROUGH THE GREAT LAKES AND NORTHEAST. DETAILS WILL DEPEND
ON THE STORM'S EXACT TRACK AND STRENGTH WHICH ARE YET TO BE
RESOLVED, SO SOME ADJUSTMENTS TO THE FORECAST WILL BE POSSIBLE.
WITH THE EVOLVING PATTERN CHANGE LATER IN THE PERIOD, THE NEXT
SYSTEM TO REACH THE WEST COAST WILL BRING ITS BRIEF PERIOD OF
LOCALLY MODERATE TO HEAVY RAINFALL/MOUNTAIN SNOW TO THE PACIFIC
NORTHWEST AND NORTHERN CALIFORNIA AROUND MIDWEEK WITH LIGHTER
TOTALS THEN EXTENDING INTO THE ROCKIES. THE SOUTH MAY SEE A
REBOUND IN RAINFALL BY NEXT SATURDAY AS A FRONT LINGERING OVER THE
GULF LIFTS BACK NORTHWARD AHEAD OF AN APPROACHING COLD FRONT.
THE FORECAST PATTERN SHOULD MAINTAIN HIGHS 5-15F BELOW NORMAL OVER
THE SOUTHERN TWO-THIRDS OR SO OF THE WEST THROUGH THE PERIOD, WITH
READINGS CLOSE TO OR SLIGHTLY ABOVE NORMAL OVER THE FAR NORTH.
VERY WARM TEMPERATURES OVER THE EASTERN HALF OF THE COUNTRY SHOULD
ERODE FROM WEST TO EAST MID-LATE WEEK WITH SYSTEM/FRONTAL PASSAGE.
AHEAD OF THIS SYSTEM, EXPECT A BROAD AREA OF LOWS 15-25F ABOVE
NORMAL AND HIGHS 10-20F ABOVE NORMAL. MOST DAILY RECORDS SHOULD
BE FOR WARM LOWS, WHILE THE BEST CHANCE FOR RECORD HIGHS STILL
APPEARS TO BE OVER SOUTHEASTERN TEXAS AND LOWER MISSISSIPPI VALLEY
ON TUESDAY.
KEBEDE/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
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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