521
FXUS02 KWBC 080653
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
152 AM EST THU FEB 08 2024
VALID 12Z SUN FEB 11 2024 - 12Z THU FEB 15 2024
..OVERVIEW
SPLIT FLOW ACROSS THE NATION INTO EARLY NEXT WEEK FEATURES A
NORTHERN STREAM WEAK SHORTWAVE THROUGH THE GREAT LAKES AND MORE
NOTABLE, AN AMPLIFIED UPPER SHORTWAVE OVER THE SOUTHWEST. THE
LATTER WILL SHIFT STEADILY THROUGH THE MID-SOUTH MONDAY AND
TUESDAY ASSOCIATED WITH A DEEPENING LOW PRESSURE SYSTEM AT THE
SURFACE BRINGING HEAVY RAINFALL POTENTIAL TO PARTS OF THE
SOUTHEAST/MID-ATLANTIC AND SNOW ACROSS THE NORTHEAST. AS THIS
SYSTEM EXITS THE NORTHEAST LATE TUESDAY, THE FLOW BEHIND IT SHOULD
BECOME MORE ZONAL WITH A WEAK SHORTWAVE THROUGH THE NORTHERN TIER
WEDNESDAY-THURSDAY AND A COUPLE OF WEAK SHORTWAVES INTO THE WEST
COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE
OVERALL PATTERN SHIFTING FROM AMPLIFIED IN THE EARLY PERIOD TO
MORE ZONAL/WEAKER SYSTEMS LATE PERIOD, BUT THERE REMAIN PLENTY OF
VARIABILITY IN THE DETAILS. THE MAIN SYSTEM OF INTEREST IN THE
PERIOD CONCERNS THE POTENTIAL DEVELOPMENT AND TRACK OF A SOUTHERN
TO EASTERN U.S., THEN WESTERN ATLANTIC, COASTAL STORM EARLY NEXT
WEEK WITH ASSOCIATED INLAND AND MARITIME IMPACTS. MODELS HAVE
SHOWN MUCH BETTER AGREEMENT IN THIS SYSTEM COMPARED TO A FEW DAYS
AGO, BUT THERE ARE STILL SOME NOTABLE TIMING ISSUES. THE 12Z (FEB
7) ECMWF RUN WAS FASTER WITH THE LOW THROUGH THE SOUTHEAST AND OFF
THE MID-ATLANTIC COAST MONDAY-TUESDAY COMPARED TO THE
DETERMINISTIC GFS, UKMET, AND CMC, BUT THE 00Z RUN TONIGHT CAME IN
A LITTLE SLOWER. STILL SOME CONSIDERABLE RUN TO RUN VARIABILITY
WITH THE LOW, SO ADDITIONAL ADJUSTMENTS ARE LIKELY IN THE COMING
DAYS. A NEARLY EQUAL BLEND OF THE FOUR DETERMINISTIC SOLUTIONS
SEEMED TO GIVE A GOOD MIDDLE GROUND STARTING POINT FOR DAYS 3-5
WITH THIS SYSTEM AND MAINTAINED FAIRLY GOOD WPC CONTINUITY.
OTHERWISE, AS THE FLOW TURNS MORE ZONAL AND STABLE, USED A BLEND
OF THE ENSEMBLE MEANS WITH THE MORE AGREEABLE GFS AND ECMWF FOR
THE LATER PERIODS. THIS HELPED TO MITIGATE ANY OF THE SMALLER
SCALE DETAIL UNCERTAINTIES.
..OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
INCREASED MOISTURE RETURN AHEAD OF THE MAIN SYSTEM OVER THE
SOUTHWEST WILL CONTINUE FROM THE VERY END OF THE SHORT RANGE
PERIOD INTO THE START OF THE MEDIUM RANGE PERIOD/SUNDAY TO FUEL
HEAVY RAINFALL POTENTIAL FROM THE LOWER MISSISSIPPI VALLEY INTO
THE SOUTHEAST. REPEAT/TRAINING OF ACTIVITY ALONG A FRONTAL
BOUNDARY, COMBINED WITH ANOMALOUS MOISTURE AND SOME INSTABILITY,
MAY TRIGGER A FLASH FLOOD RISK, AND A MARGINAL RISK CONTINUES TO
BE HIGHLIGHTED ON THE DAY 4/SUNDAY EXCESSIVE RAINFALL OUTLOOK
ACROSS THE SOUTHEAST. AS THE MAIN LOW PRESSURE STARTS TO DEEPEN
ACROSS THE SOUTH-CENTRAL PLAINS, HEAVY RAINFALL MAY BE FAVORED IN
THIS REGION/JUST TO THE NORTH OF THE LOW GIVEN UPPER LEVEL
DYNAMICS. LATEST RUNS OF MODELS HAVE INDICATED SOME SECONDARY QPF
MAXES ACROSS PARTS OF CENTRAL-EASTERN OKLAHOMA, SO A SMALL
MARGINAL RISK WAS ADDED TO SUNDAY'S OUTLOOK FOR THIS POTENTIAL.
SOME ACCUMULATING SNOWFALL IS ALSO POSSIBLE ACROSS THE FAR
NORTHERN PORTION OF THE PRECIPITATION SHIELD ACROSS THE CENTRAL
PLAINS/MIDDLE MISSISSIPPI VALLEY AS WELL. AS THE DEEPENING SYSTEM
SHIFTS EAST, HEAVY RAINFALL SHOULD LIFT NORTHWARD INTO PARTS OF
THE MID-ATLANTIC AND NORTHEAST ON MONDAY, BUT LOOKS TO BE
PROGRESSIVE ENOUGH TO PRECLUDE ANY KIND OF RISK AREA ON THE DAY
5/MONDAY ERO AT THIS POINT. ALSO INCREASING POTENTIAL FOR
WRAP-BACK ACCUMULATING SNOWS ACROSS THE APPALACHIANS/INTERIOR
NORTHEAST AROUND MONDAY-TUESDAY BEFORE THE WHOLE SYSTEM EXITS
OFFSHORE. BEHIND THIS SYSTEM, CONDITIONS ACROSS MUCH OF THE CONUS
SHOULD DRY OUT MID NEXT WEEK BESIDES PERIODIC INTRUSIONS FROM THE
PACIFIC TO BRING SOME MODEST PRECIPITATION TO PARTS OF THE
NORTHWEST.
AHEAD OF THE EASTERN U.S. SYSTEM, TEMPERATURES SUNDAY INTO MONDAY
COULD BE 5-15 DEGREES ABOVE AVERAGE, WITH MORNING LOWS EVEN MORE
ANOMALOUSLY WARM GIVEN CLOUDS AND HUMIDITY. THE EAST SHOULD
MODERATE BACK CLOSER TO NORMAL TUESDAY AND BEYOND. IN CONTRAST,
THE SOUTHWEST/CALIFORNIA SHOULD BE COOL WITH UPPER SYSTEM PASSAGE,
ESPECIALLY DAYTIME HIGHS THAT MAY BE 10-15F BELOW NORMAL ON SUNDAY
BEFORE MODERATING. SOME RIDGING IN THE UPPER PATTERN MAY ALSO
SUPPORT ABOVE NORMAL TEMPERATURES ACROSS PARTS OF THE NORTHERN
TIER THROUGH ABOUT WEDNESDAY.
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, 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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