094
FXUS02 KWBC 132009
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
309 PM EST MON NOV 13 2023
VALID 12Z THU NOV 16 2023 - 12Z MON NOV 20 2023
...PATTERN OVERVIEW AND GUIDANCE EVALUATION/PREDICTABILITY
ASSESSMENT...
IT REMAINS THE CASE THAT THE UPPER PATTERN ACROSS THE LOWER 48
WILL FEATURE A SLOWLY-MOVING UPPER LOW OFF THE COAST OF CALIFORNIA
THAT GRADUALLY WORKS INLAND NEXT WEEKEND, OUTPACED BY NORTHERN
STREAM UPPER RIDGING MOVING INTO SOUTHWESTERN CANADA. THE 00/06Z
GUIDANCE CYCLE CONTINUED TO SHOW SOME SPREAD IN TIMING OF THE
UPPER LOW MOVING EAST AND OPENING INTO A TROUGH, WITH THE CMC ON
THE FAST SIDE, GFS RUNS ON THE SLOWER SIDE, AND THE ECMWF A
SEEMINGLY GOOD MIDDLE GROUND. THE NEWER 12Z MODEL RUNS ARE
CLUSTERING SLOWER IN GENERAL. THIS TROUGH REACHES THE CENTRAL U.S.
EARLY NEXT WEEK, COOLING TEMPERATURES AFTER A MILD LATE
WEEK-WEEKEND PERIOD. A MODEL/ENSEMBLE BLEND SEEMED TO WORK AS AN
AGREEABLE POSITION FOR THAT TROUGH AXIS/DEPTH.
A NORTHERN TIER TROUGH AND A COLD FRONT WILL MOVE QUICKLY EASTWARD
DURING THE LATTER PART OF THE WEEK, WHILE SOUTHERN STREAM ENERGY
ACROSS THE SOUTHEAST CARRIES A SURFACE LOW ACROSS FLORIDA FOR SOME
ENHANCED PRECIPITATION. THESE FEATURES LOOK MERGE/INTERACT AROUND
SATURDAY FOR INCREASED PRECIPITATION IN THE NORTHEAST. MODELS ARE
REASONABLY AGREEABLE WITH THESE FEATURES AND THEIR EVOLUTION UNTIL
EARLY NEXT WEEK WHEN MODELS HAVE VARYING DEGREES OF DIGGING ENERGY
ON THE WEST SIDE OF THE TROUGH NEAR THE GREAT LAKES. GFS RUNS
INDICATE MORE DIGGING VORTICITY THAN THE THE ECMWF/CMC AND THE
ENSEMBLE MEANS, WHICH ALSO DISPLACES A SURFACE HIGH FARTHER WEST
IN THE GFS COMPARED TO OTHER GUIDANCE. A SOLUTION MORE ALONG THE
LINES OF THE ECMWF AND ENSEMBLE MEANS LOOKED BEST.
OVERALL, FAVORED A MULTI-MODEL DETERMINISTIC BLEND OF THE 00/06Z
ECMWF/GFS/CMC/UKMET FOR THE EARLY PART OF THE FORECAST PERIOD,
GRADUALLY INCREASING TO A MAJORITY OF ENSEMBLE MEANS FOR THE LATE
PERIOD AS SPREAD INCREASED WHILE MAINTAINING SOME ECMWF PROPORTION
ESPECIALLY. THIS GENERALLY SHOWED GOOD CONTINUITY WITH THE
PREVIOUS FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
BY THE START OF THE PERIOD THURSDAY, THE HEAVIEST RAIN SHOULD BE
PULLING AWAY FROM THE FLORIDA PENINSULA INTO THE WESTERN ATLANTIC.
BUT LINGERING RAIN FROM EASTERLY FLOW AND A SLOW RELAXATION OF
WELL ABOVE NORMAL PRECIPITABLE WATER COULD CREATE SOME LINGERING
FLOODING CONCERNS ACROSS THE EASTERN COAST OF FLORIDA, SO
MAINTAINED A MARGINAL RISK OVER ATLANTIC COASTAL AREAS JUST IN
CASE. URBAN AREAS WOULD BE MOST SUSCEPTIBLE TO EXCESSIVE RAINFALL.
FARTHER NORTH, LIGHT PRECIPITATION MOVING ACROSS THE UPPER GREAT
LAKES/OHIO VALLEY THURSDAY WITH A COLD FRONT COULD TREND HEAVIER
LATE WEEK ACROSS THE APPALACHIANS EASTWARD AS ATLANTIC MOISTURE
GETS PULLED IN. POTENTIAL PRECIPITATION AMOUNTS AND TYPES CONTINUE
TO VARY IN THE MODEL GUIDANCE ESPECIALLY OVER THE NORTHEAST,
DEPENDENT ON THE LOCATION OF A COASTAL LOW AND THE FRONT BEHIND IT.
FOR THE WEST/SOUTHWEST, THE SLOW APPROACH OF THE CLOSED SOUTHERN
STREAM UPPER LOW WILL ONLY GRADUALLY BRING IN BOUTS OF LIGHT TO
MODERATE/TERRAIN ENHANCED RAIN AND MOUNTAIN SNOW THAT EXPAND
EASTWARD IN TIME. THE DELAY IN THE HEIGHT FALLS LIKELY LESSENS THE
STRONGER MOISTURE FLUX INTO THE AREA AS THE SYSTEM FILLS BEFORE
MOVING ASHORE, BUT MOST AREAS OF CALIFORNIA INTO THE SOUTHWEST
WILL SEE AT LEAST MEASURABLE RAINFALL (ESPECIALLY COASTAL AREAS)
OUTSIDE SOME OF THE SHADOWED DESERTS. GIVEN THE CONSISTENT SLOWER
AND DRIER TREND IN THE GUIDANCE, NO EXCESSIVE RAINFALL RISK AREAS
ARE IN PLACE. AS THE AMPLIFIED UPPER SYSTEM FINALLY CROSSES THE
DIVIDE, RETURN FLOW OUT OF THE GULF OF MEXICO WILL HELP INCREASE
MOISTURE OVER THE PLAINS THEN MISSISSIPPI VALLEY, WITH RAIN
EXPANDING IN COVERAGE LATE WEEKEND INTO EARLY NEXT WEEK. AT THE
SAME TIME, ANOTHER PACIFIC SYSTEM, BUT IN THE NORTHERN STREAM,
WILL PROGRESS INLAND FROM THE NORTHWEST TO THE NORTH-CENTRAL
ROCKIES FOR THE WEEKEND ALONG WITH A QUICK SWATH OF RAIN AND
MOUNTAIN SNOW BEFORE EJECTING INTO THE NORTH-CENTRAL STATES TO
LIFT LIMITED MOISTURE INTO THE REGION.
ABOVE AVERAGE TEMPERATURES SHOULD BE WIDESPREAD ACROSS MUCH OF THE
CONUS ON THURSDAY, WITH THE HIGHEST ANOMALIES OF 15-25F ABOVE
NORMAL STRETCHING FROM THE CENTRAL/NORTHERN PLAINS TO THE UPPER
MIDWEST. THOUGH TEMPERATURES LOOK TO MODERATE SLIGHTLY THERE ON
FRIDAY, ABOVE NORMAL TEMPERATURES SHOULD BE PERSISTENT INTO THE
WEEKEND BUT START TO COOL ON MONDAY UNDER THE INCOMING TROUGH.
TEMPERATURES WILL BE WARMER THAN AVERAGE IN THE EAST
THURSDAY-FRIDAY BUT MODERATE CLOSE TO NORMAL ON SATURDAY, WHILE
TEMPERATURES IN THE WEST SHOULD GENERALLY BE NEAR NORMAL.
TATE/SCHICHTEL
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: THERE ARE NO HAZARDS DURING THIS FORECAST PERIOD.
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY
MESSAGES 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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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