013
FXUS02 KWBC 121858
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 PM EST SUN NOV 12 2023
VALID 12Z WED NOV 15 2023 - 12Z SUN NOV 19 2023
...HEAVY RAINFALL POTENTIAL FOR PARTS OF THE NORTHERN/NORTHEASTERN
GULF COAST WEDNESDAY...
...PATTERN OVERVIEW AND GUIDANCE EVALUATION/PREDICTABILITY
ASSESSMENT...
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. IN THE EAST, A TROUGH IN THE SOUTHEAST
WILL MOVE EASTWARD WITH ITS SURFACE REFLECTION CARRYING A LOW
PRESSURE CENTER ACROSS FLORIDA. THIS SYSTEM MAY MERGE/INTERACT
WITH A FRONTAL BOUNDARY MOVING THROUGH THE GREAT LAKES TO FORM A
DEEPER AREA OF LOW PRESSURE NEAR OR JUST OFFSHORE THE
MID-ATLANTIC/NORTHEAST NEXT WEEKEND. MUCH OF THE REST OF THE
MIDDLE OF THE COUNTRY WILL BE DRY WITH MILD TEMPERATURES FOR
MID-NOVEMBER.
THE GUIDANCE HAS LARGELY TRENDED SLOWER WITH THE APPROACH OF THE
LUMBERING UPPER LOW OFF CA, WITH THE DETERMINISTIC MODELS LEADING
THE WAY OF THE ENSEMBLE MEANS. WITH A STEADY TREND SLOWER IN THE
MULTI-DAY ENSEMBLE TRENDS, WENT FULLY TOWARD THE SLOWER SOLUTIONS
VIA A BLEND OF THE 00/06Z GFS AND 00Z ECMWF/UKMET FOR MUCH OF THE
FORECAST. BY NEXT WEEKEND, THE AGREEMENT WAS ACTUALLY BETTER AS
THE UPPER LOW OPENS UP INTO A TROUGH PROGRESSING ACROSS THE GREAT
BASIN/FOUR CORNERS/SOUTHERN ROCKIES. IN THE EAST, MULTI-MODEL
BLEND SUFFICED WITH THE HANDLING OF THE GULF LOW, BUT SPREAD
INCREASED RATHER SMARTLY BY LATER IN THE PERIOD AS THE TWO SYSTEMS
INTERACTED ALONG/OFF THE EAST COAST. FOR NOW, ENSEMBLES KEEP SUCH
INTERACTION ALONG/EAST OF 70W WHICH WOULD LIMIT IMPACTS TO PARTS
OF NEW ENGLAND.
..WEATHER/HAZARDS HIGHLIGHTS
THE SLOWER AND DRIER TREND IN THE GUIDANCE OVER CALIFORNIA ALLOWED
FOR THE REMOVAL OF THE MARGINAL RISK OUTLINES FOR DAYS 4-5. OVER
THE NORTHERN GULF OF MEXICO, FOCUSED THE DAY 4 (WED) HEAVY RAIN
THREAT AROUND THE FL PANHANDLE WHERE FAVORABLE CONVERGENCE MAY
SUPPORT HEAVIER RAIN RATES TO THE NORTH OF THE LOW. THOUGH
RAINFALL IS LIKELY OVER MUCH OF THE SUNSHINE STATE, THE EVOLUTION
OF THE SYSTEM MAY TRANSLATE THE BULK OF THE HEAVIER RAIN EAST OF
THE PENINSULA BY THURSDAY. THEREFORE, REMOVED THE MARGINAL RISK
AREA FROM EASTERN FL THOUGH THERE IS POTENTIAL TO BRING AN AREA
BACK IN DEPENDING ON HOW THINGS EVOLVE.
FOR THE WEST/SOUTHWEST, THE SLOW APPROACH OF THE UPPER LOW WILL
ONLY GRADUALLY BRING IN BOUTS OF LIGHT TO PERHAPS MODERATE 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 WILL
SEE AT LEAST MEASURABLE RAINFALL (ESPECIALLY COASTAL AREAS)
OUTSIDE SOME OF THE SHADOWED DESERTS. AS THE UPPER SYSTEM FINALLY
CROSSES THE DIVIDE, SOME RETURN FLOW OUT OF THE WESTERN GULF WILL
HELP INCREASE MOISTURE OVER THE PLAINS WITH RAIN EXPANDING IN
COVERAGE LATE NEXT WEEKEND. AT THE SAME TIME, ANOTHER PACIFIC
SYSTEM, BUT IN THE NORTHERN STREAM, WILL MOVE INTO THE PAC NW WITH
SOME RAIN AND MOUNTAIN SNOW. OVER THE SOUTHEAST AND EAST COAST,
THE APPROACHING COLD FRONT FROM THE NORTH AND GULF LOW WILL SPREAD
RAIN ALONG THE I-95 CORRIDOR LATER THIS WEEK INTO THE START OF THE
WEEKEND, BUT THE EXTENT/AMOUNTS ARE STILL FAIRLY UNCERTAIN AND
DEPENDENT ON THE TRACK OF THE SYSTEM AND HOW FAR OFFSHORE IT MAY
BE.
TEMPERATURES WILL LARGELY BE NEAR TO ABOVE NORMAL FOR MOST OF THE
CONUS, ESPECIALLY OVER THE UPPER MIDWEST WHERE RIDGING WILL
INCREASE BY NEXT WEEKEND AMID DRY CONDITIONS. NEAR TO SLIGHTLY
BELOW TEMPERATURES ARE EXPECTED FOR THE SOUTHEAST AND PARTS OF THE
SOUTHWEST DUE TO CLOUDIER AND WETTER THAN NORMAL CONDITIONS.
FRACASSO
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, 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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