985
FXUS02 KWBC 071856
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 PM EDT FRI OCT 07 2022
VALID 12Z MON OCT 10 2022 - 12Z FRI OCT 14 2022
..PATTERN OVERVIEW
A MID-UPPER RIDGE IS CURRENTLY FORECAST TO KEEP A STRONG HOLD OVER
THE EASTERN PACIFIC TO GULF OF ALASKA THROUGH NEXT WEEK, WHILE ITS
EXACT PLACEMENT AND AXIS MAY MEANDER A BIT FROM DAY TO DAY. WITH
THAT FEATURE IN PLACE, POTENT ENERGY IS FORECAST TO SPILL
SOUTHEASTWARD TO ITS EAST, CREATING AND AMPLIFYING A TROUGH
DOWNSTREAM IN THE NORTH-CENTRAL U.S. INITIALLY AND THEN TRACKING
INTO THE EAST. THE TROUGH WILL PUSH ANOTHER FAIRLY STRONG COLD
FRONT EASTWARD WITH COOLER TEMPERATURES BEHIND IT AND RAIN CHANCES
BECOMING WIDESPREAD AHEAD OF IT ACROSS THE CENTRAL U.S.
TUESDAY-WEDNESDAY AND INTO THE EAST THURSDAY-FRIDAY.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
MOST MODEL GUIDANCE HAS BEEN MORE CONSISTENT FOR THE PAST FEW
CYCLES REGARDING THE PACIFIC RIDGE/HIGH DIRECTING ENERGY CURRENTLY
DEVELOPING OVER THE BERING SEA TO THE RIDGE'S EAST, WITH MOST IF
NOT ALL OF THIS ENERGY REMAINING IN THE NORTHERN STREAM AND
FORMING A STRONG UPPER LOW IN CENTRAL CANADA WITH ITS TROUGHING
INFLUENCE EXTENDING INTO THE CENTRAL U.S. BY MIDWEEK AND SHIFTING
EASTWARD LATE WEEK. THE CMC RUNS REMAIN A HOLDOUT IN MAINTAINING
WHAT SOME OTHER MODELS WERE ALSO SHOWING A DAY OR TWO AGO, NAMELY,
SOME ENERGY SPLITTING OFF FROM THE NORTHERN STREAM TROUGH TO HELP
FORM A CUTOFF LOW OVER THE WEST FOR THE LATTER HALF OF THE WEEK. A
HANDFUL OF ENSEMBLE MEMBERS FROM THE CMC/EC/GEFS SUITES DISPLAY
SOME INDICATION OF THIS, BUT THE MAJORITY LEAN TOWARD THE BETTER
GFS/ECMWF/UKMET CONSENSUS. THIS LATTER GUIDANCE DOES SHOW SOME
TROUGHING PERHAPS SEPARATING INTO A WEAK CLOSED LOW
WEDNESDAY-FRIDAY, BUT THIS ARISES FROM A DIFFERENT SHORTWAVE THAT
DIVES SOUTH ACROSS THE WEST COAST STATES DURING THE SHORT RANGE
PERIOD. WITH TELECONNECTIONS WITH THE POSITIVE HEIGHT ANOMALY OVER
THE GULF OF ALASKA AND THE NEGATIVE HEIGHT ANOMALY NORTH OF HAWAII
ALSO LEANING TOWARD A NON-CMC TYPE SOLUTION, THE WPC MODEL BLEND
WAS INITIALLY COMPOSED OF THE 00Z AND 06Z GFS RUNS AND THE 00Z
ECMWF AND UKMET. WITHIN THE TENTATIVE AGREEMENT FOR THE TROUGHING,
THERE REMAINS CONSIDERABLE VARIABILITY IN PLACEMENT OF THE
CENTROID OF THE UPPER LOW FOR MIDWEEK AND BEYOND, WITH MODELS FROM
THE 00Z/06Z AND NEWER 12Z CYCLES SHOWING A VARIETY FROM
NORTH-CENTRAL CANADA INTO THE NORTH-CENTRAL CONUS. THE 12Z GFS AND
ECMWF DETERMINISTIC MODELS ARE GENERALLY ON THE SOUTHERN SIDE.
THIS AFFECTS THE EXACT FRONTAL POSITION/TIMING AND DEVELOPMENT OF
LOW PRESSURE WAVES ALONG THE FRONT. THE LATTER PART OF THE WPC
MODEL BLEND INCREASED THE PROPORTIONS OF THE GEFS AND EC ENSEMBLE
MEANS TO JUST OVER HALF BY THE END OF THE PERIOD TO REDUCE
INDIVIDUAL MODEL DIFFERENCES. THOUGH THERE HAS BEEN SOME
FORECAST/MODEL CONVERGENCE, FORECAST CONFIDENCE STILL REMAINS A
BIT BELOW AVERAGE AT THIS TIME GIVEN THE MODEL VARIABILITY.
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
THE AMPLIFYING UPPER TROUGH AND A STRONG COLD FRONT REACHING THE
NORTHERN PLAINS AND UPPER MIDWEST WILL LIKELY PRODUCE SHOWERS AND
SOME THUNDERSTORMS FROM THE CENTRAL PLAINS TO THE GREAT LAKES,
WITH LIGHT TO MODERATE TOTALS POSSIBLE THROUGH TUESDAY. RAIN IS
FORECAST TO BECOME MORE WIDESPREAD IN COVERAGE AS THE FRONT
PROGRESSES ACROSS THE MISSISSIPPI VALLEY AND OHIO/TENNESSEE
VALLEYS MIDWEEK AND TOWARD THE EAST IN THE LATTER PART OF THE WEEK
AS THE FRONT TAPS INTO DEEPER MOISTURE. CURRENTLY, THE HEAVIEST
RAINFALL TOTALS ARE EXPECTED FOR THE INTERIOR NORTHEAST AS THE
FRONT MAY SLOW THERE AS IT PIVOTS. ELSEWHERE, THE CONVECTION
ACROSS THE SOUTHERN ROCKIES AND ARIZONA IS FINALLY EXPECTED TO
SUBSIDE GOING INTO THE MIDDLE OF THE WEEK AS THE UPPER LOW/TROUGH
WEAKENS. SOME HIGH ELEVATION SNOW SHOWERS ARE ALSO POSSIBLE FOR
THE HIGHEST TERRAIN OF THE CENTRAL AND NORTHERN ROCKIES ON TUESDAY
AND WEDNESDAY. SHOWERS REMAIN POSSIBLE OVER FLORIDA IN THE
VICINITY OF A FRONT AS WELL.
ABOVE NORMAL TEMPERATURES ARE NOW FORECAST TO PERSIST THROUGH MUCH
OF NEXT WEEK ACROSS THE NORTHWESTERN U.S. WITH THE UPPER RIDGE
JUST OFF THE COAST. IN THE EAST, TEMPERATURES SHOULD BE MODERATING
EARLY IN THE WEEK AFTER A RELATIVELY CHILLY WEEKEND FOR MOST
LOCATIONS. TEMPERATURES AHEAD OF THE MAIN COLD FRONT WILL BE WARM
ACROSS MOST OF THE PLAINS AND MIDWEST STATES AHEAD OF THE FRONT
PASSING THROUGH TUESDAY-WEDNESDAY. BEHIND THE FRONT, HIGHS ARE
LIKELY TO BE ABOUT 5-15 DEGREES BELOW AVERAGE TO CLOSE OUT THE
WORKWEEK FOR THE OHIO VALLEY AND GREAT LAKES, WITH POTENTIAL FOR
FROST AT NIGHT.
TATE/HAMRICK
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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