741
FXUS02 KWBC 100700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST SUN NOV 10 2024
VALID 12Z WED NOV 13 2024 - 12Z SUN NOV 17 2024
... ANOTHER ATMOSPHERIC RIVER TO BRING HEAVY RAIN AND MOUNTAIN
SNOW THREATS TO PARTS OF THE NORTHWEST MID NEXT WEEK...
..OVERVIEW
A FAIRLY PROGRESSIVE PATTERN IS FORECAST THROUGH LATE NEXT WEEK
AND INTO NEXT WEEKEND. A PROGRESSIVE BUT SOMEWHAT AMPLIFIED TROUGH
WILL PROGRESS FROM THE CENTRAL TO EASTERN U.S. BRINGING MAINLY
LIGHT TO MODERATE MUCH-NEEDED PRECIPITATION FOR THE MIDWEST TO MID-
ATLANTIC/NORTHEAST, WITH SOME ENHANCED RAINFALL SOUTH NEAR THE
GULF COAST COMBINED WITH TROPICAL MOISTURE OUT OF THE GULF. UPPER
RIDGING ON EITHER SIDE OF THIS TROUGH WILL PROMOTE PERIODS OF
WARMER TEMPERATURES ACROSS THE EASTERN HALF OF THE NATION THROUGH
THE PERIOD. MEANWHILE OUT WEST, AN ATMOSPHERIC RIVER WILL IMPACT
PARTS OF THE NORTHWEST AROUND MIDWEEK BRINGING HEAVY RAIN AND SNOW
THREATS, WITH ADDITIONAL ROUNDS OF PRECIPITATION LATER IN THE WEEK
WITH TROUGH RELOADING ALONG THE COAST. SOME MODEL INDICATIONS THE
OVERALL PATTERN OVER THE CONUS MAY TURN MORE AMPLIFIED NEXT WEEKEND
WITH TROUGHING OVER THE WEST/SOUTHWEST AND STRONGER RIDGING OVER
THE EAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE REMAINS REASONABLY AGREEABLE ON THE LARGE SCALE
PROGRESSIVE PATTERN, AND EXACT TIMING AND AMPLITUDE OF THE TROUGHS
AND RIDGES ARE THE MOST UNCERTAIN ASPECTS OF THE FORECAST. AN
INITIAL SHORTWAVE EXITING THE NORTHEAST ON WEDNESDAY SHOWS SOME
UNCERTAINTY WITH ENERGY THAT LINGERS OFF THE COAST AND INTERACTS
WITH THE NEXT TROUGH BEHIND IT. THE CENTRAL U.S. TROUGH HAS TRENDED
SLOWER AND A LITTLE BIT MORE AMPLIFIED AND THE WPC FORECAST
TRENDED THAT DIRECTION TOO. THE 18Z GFS WAS THE FASTEST OF THE
GUIDANCE WITH THIS TROUGH, BUT THE BETTER CONSENSUS (ALONG WITH THE
AI/ML MODELS) WERE SLOWER. THE NEW 00Z GFS (AVAILABLE AFTER THE
WPC FORECAST WAS GENERATED) DID TREND SLOWER/SHARPER THAN ITS
PREVIOUS RUN LENDING CONFIDENCE TO THE CHANGE IN WPC CONTINUITY.
LOTS OF UNCERTAINTY OUT WEST, ESPECIALLY BY NEXT WEEKEND, WITH THE
DEEP TROUGHING. ECMWF HAS BEEN MORE AMPLIFIED/DEEPER, SENDING
ENERGY FARTHER SOUTH THAN THE GFS AND CMC, BUT THE LATEST 00Z RUNS
OF BOTH THE GFS AND CMC HAVE TRENDED TOWARDS THE ECMWF, SIGNALING A
POSSIBLY MORE AMPLIFIED PATTERN BY LATE NEXT WEEKEND AND BEYOND
THE MEDIUM RANGE PERIOD.
THE WPC FORECAST FOR DAYS 3 AND 4, LEANED MORE HEAVILY ON THE
ECMWF, CMC, AND UKMET (SLOWER TROUGH INTO THE EAST). BY THE MIDDLE
TO LATTER HALF OF THE PERIOD THOUGH, FAVORED THE ENSEMBLE MEANS
WHICH WERE A GOOD MIDDLE GROUND SOLUTION FOR THE TROUGHING IN THE
WEST.
..WEATHER/HAZARDS HIGHLIGHTS
THE MAIN CONCERN FOR WEATHER HAZARDS WILL BE WITH A MODEST
ATMOSPHERIC RIVER SET TO BEGIN IMPACTING THE PACIFIC NORTHWEST ON
TUESDAY (JUST BEFORE THE MEDIUM RANGE PERIOD BEGINS) AND MAY LAST A
FEW DAYS. HEAVY RAIN AND MOUNTAIN SNOW POTENTIAL WILL LAST THROUGH
WEDNESDAY WITH AMPLE MOISTURE ANOMALIES AND SOME INSTABILITY ALONG
THE COAST CONTINUING THE NEED FOR A MARGINAL RISK FOR PARTS OF
WESTERN WASHINGTON/OREGON AND INTO NORTHWEST CALIFORNIA ON THE DAY
4/WEDNESDAY ERO. SNOW MAY BE HEAVY IN THE MOUNTAINS, PARTICULARLY
THE CASCADES AS THE WEEK PROGRESSES, AND SOME MODEST SNOW AMOUNTS
INTO THE NORTHERN ROCKIES AS WELL. AFTER WEDNESDAY, PRECIPITATION
SHOULD TREND LIGHTER AS THE MOISTURE MOVES INLAND, BUT SOME
LINGERING PRECIPITATION ALONG THE COAST MAY BE POSSIBLE AS WEAKER
ENERGY RELOADS INTO THE LARGER SCALE TROUGH.
THE SLOWER AND SLIGHTLY MORE AMPLIFIED TROUGH ACROSS THE CENTRAL
U.S. ON WEDNESDAY SHOULD ALLOW FOR BETTER TAPPING OF GULF OF MEXICO
TROPICAL MOISTURE AND INTERACTION WITH A COASTAL FRONT AND THE
APPROACHING SHORTWAVE. MODELS HAVE TICKED UPWARDS IN TERMS OF QPF
ACROSS PARTS OF THE CENTRAL GULF COAST FROM LOUISIANA INTO
MISSISSIPPI AND WESTERN ALABAMA. AS SUCH, A MARGINAL RISK WAS ADDED
FOR THIS REGION TO THE DAY 4/WEDNESDAY OUTLOOK. FARTHER NORTH,
MOISTURE ALONG THE FRONT SHOULD BRING MODEST PRECIPITATION TO THE
EASTERN HALF OF THE COUNTRY THROUGH ABOUT THURSDAY, BUT CONTINUED
MODEL DISAGREEMENTS IN THE TROUGH POSITION/EVOLUTION DO CAUSE SOME
SPREAD FOR THE PRECIPITATION AMOUNTS/INTENSITY ON INDIVIDUAL DAYS.
MOST OF THIS PRECIPITATION LOOKS TO FALL AS RAIN GIVEN THE WARMER
THAN NORMAL TEMPERATURES, UNTIL SOME ICE AND SNOW ARE POSSIBLE IN
HIGHER ELEVATIONS OF THE INTERIOR NORTHEAST MID- TO LATER WEEK.
WINDS MAY BE GUSTY BEHIND THE ASSOCIATED LOW PRESSURE AND FRONTAL
SYSTEM IN THE NORTHERN ROCKIES TO NORTHERN PLAINS TUESDAY-
WEDNESDAY.
WHILE SYSTEM PROGRESSION WILL PROVIDE SOME DAY-TO-DAY VARIABILITY,
MOST OF THE LOWER 48 TO THE EAST OF THE ROCKIES SHOULD SEE ABOVE
NORMAL TEMPERATURES MUCH OF THE WEEK. MEANWHILE LINGERING SNOW
COVER IN THE CENTRAL/SOUTHERN ROCKIES WILL PROMOTE COOLER THAN
NORMAL HIGHS THERE THROUGH ABOUT THURSDAY WHILE THE WEST OTHERWISE
SHOULD TREND COLDER WITH MORE AMPLIFIED TROUGHING MOVING INTO THE
REGION LATE WEEK AND INTO NEXT WEEKEND.
SANTORELLI
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 FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page