980
FXUS02 KWBC 081922
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
322 PM EDT MON APR 8 2024
VALID 12Z THU APR 11 2024 - 12Z MON APR 15 2024
***AREAS OF HEAVY RAIN LIKELY TO REACH THE EAST COAST BY THURSDAY
WITH STRONG STORMS POSSIBLE OVER THE SOUTHEAST***
..GENERAL OVERVIEW
A SOUTHWEST/SOUTHERN PLAINS STORM SYSTEM WILL BE TREKKING ACROSS
THE CENTRAL U.S. MIDWEEK BEFORE ADVANCING THROUGH THE OHIO VALLEY,
GREAT LAKES AND EAST LATER IN THE WEEK. THE OHIO VALLEY SURFACE
LOW PRESSURE SHOULD LIFT INTO EASTERN CANADA AS UPPER ENERGY
CONSOLIDATES INTO A GREAT LAKES/EASTERN CANADA UPPER LOW WHILE THE
TRAILING TROUGH CONTINUES THROUGH THE EAST COAST/NORTHEAST. BROAD
AREAS OF RAINFALL WITH EMBEDDED HEAVIER DOWNPOURS, WILL ACCOMPANY
THIS SYSTEM. DRIER AIR WILL FILTER IN THE WAKE OF THIS SYSTEM BY
THE WEEKEND. A TRAILING UPPER RIDGE PROGRESSING FROM THE WEST INTO
THE PLAINS/MISSISSIPPI VALLEY WILL SUPPORT SIMILAR MOVEMENT OF AN
AREA OF WELL ABOVE NORMAL TEMPERATURES. BEHIND THIS RIDGE, GUIDANCE
CONTINUES TO SHOW PRONOUNCED TRENDING FOR WHAT A GROWING CONSENSUS
SHOWS WILL BE AN UPPER LOW THAT SHOULD DROP SOUTH FROM JUST SOUTH
OF ALASKA TO OFFSHORE CALIFORNIA AND THEN TRACK INTO THE WEST,
SPREADING PRECIPITATION AHEAD OF ITS PATH.
..GUIDANCE/PREDICTABILITY ASSESSMENT
SEVERAL RUNS OF THE GUIDANCE DEPICT A LOW PRESSURE SYSTEM ADVANCING
NORTHEAST ACROSS THE OHIO VALLEY, GREAT LAKES, NEW ENGLAND AND THE
CANADIAN MARITIMES. THERE ARE SOME TIMING DIFFERENCES THAT HAVE YET
TO BE RESOLVED THAT AFFECT THE PLACEMENT OF QPF AND AMOUNTS. THE
MODEL THAT CONTINUES TO BE THE MOST CONSISTENT FROM RUN TO RUN IS
THE ECMWF WITH AN INTERMEDIATE SURFACE LOW POSITION OVER WESTERN
KENTUCKY/TENNESSEE AS OF EARLY THURSDAY, WHILE PERSISTENTLY FASTER
GFS RUNS HAVE STARTED TO NUDGE SLOWER TOWARD THE ECMWF IN RECENT
RUNS. THE CMC HAS WAFFLED BETWEEN SLOW INITIALLY TO BEING ON THE
FASTER SIDE OF THE CLUSTER. LIKE THE PREVIOUS FORECAST, LEANING
TOWARD A HEAVIER WEIGHTING OF THE ECMWF FOR THE WEEKEND AND
BEYOND.
GUIDANCE IS TRENDING TOWARD SLOWER AND DEEPER TROUGHING, AND NOW A
PRONOUNCED SIGNAL FOR AN UPPER LOW TO DROP SOUTHWARD TO A POSITION
OFFSHORE CALIFORNIA AND THEN PROGRESS INLAND REACHING THE
SOUTHWEST/FOUR CORNER REGION BY MONDAY. THE PACIFIC NORTHWEST MAY
HAVE SOME UPPER TROUGH ENTER THE REGION NEAR THE START OF THE WEEK
WHICH WOULD SUPPORT AN INCREASE IN CLOUD COVER AND POSSIBILITY OF
LIGHT PRECIPITATION MOVING ONSHORE
..WEATHER/HAZARDS HIGHLIGHTS
A LOW PRESSURE SYSTEM WILL LIKELY LIFT NORTHEASTWARD FROM THE OHIO
VALLEY THURSDAY ONWARD AND THE ASSOCIATED TRAILING COLD FRONT WILL
USHER IN A BROAD AREA OF ENHANCED PRECIPITATION ALONG THE EASTERN
SEABOARD AND GREAT LAKES REGION. THERE IS A BROAD MARGINAL RISK FOR
EXCESSIVE RAINFALL SPANNING FROM CENTRAL FLORIDA NORTH TO MICHIGAN
AND THEN EAST TO THE ATLANTIC OCEAN. A SLIGHT RISK AREA THAT WAS
ALREADY IN AFFECT FOR PARTS OF THE NORTHERN MID-ATLANTIC INTO
CENTRAL/SOUTH-CENTRAL APPALACHIANS WAS EXPANDED WITH THIS FORECAST
PACKAGE TO SPAN FROM NORTHEAST GEORGIA TO SOUTHEAST NEW YORK. THIS
REGION SHOWS THE BEST GUIDANCE OVERLAP AND CONTINUITY FOR
RELATIVELY HIGHER RAINFALL TOTALS AS WELL AS HIGHER ANTECEDENT SOIL
MOISTURE AND CURRENT STREAM FLOWS. GENERAL MODEL CONSENSUS HAS 1
TO 3+ INCHES ALONG THE APPALACHIANS OR VICINITY.
THE SYSTEM WILL CONTINUE TO ADVANCE NORTH/NORTHEAST SO BY FRIDAY
ANOMALOUS MOISTURE OVER THE NORTHEAST ALONG/AHEAD OF THE COLD
FRONT SWEEPING THROUGH THE REGION. A MARGINAL RISK IS ALREADY IN
EFFECT FOR PORTIONS OF NORTHERN NEW ENGLAND AND CONTINUES TO
REFLECT THE LEVEL OF THREAT FOR REGION ON DAY 5 GIVEN SENSITIVITY
OF SNOW COVER LIKELY TO MELTING OVER THE COMING DAYS. COLDER AIR
WILL FILTER IN WITH THE PASSAGE OF THE FRONT WHICH MAY RESULT IT
AREAS OF MIXED PRECIPITATION TYPE OR CHANGE OVER TO ALL SNOW BY
FRIDAY NIGHT AND PERSISTING INTO SATURDAY. STRONG GUSTY WINDS WILL
ACCOMPANY THIS SYSTEM. THE STORM PREDICTION CENTER IS MONITORING
THE POTENTIAL FOR SEVERE WEATHER WITH THE CONVECTION FORECAST TO
TRACK ACROSS THE SOUTHEAST ON THURSDAY. CHECK THEIR LATEST OUTLOOKS
FOR MORE INFORMATION.
FOR THE WEST, THE OVERALL PATTERN SUGGESTS A CLOSED UPPER LOW TO
DROP TO A POSITION OFFSHORE CALIFORNIA AND THEN TRACK INLAND, HAS
LED TO A LIGHTER TREND FOR WHAT RAIN/MOUNTAIN SNOW MAY REACH THE
NORTHWEST/NORTHERN ROCKIES LATE THIS WEEK BUT A BRIEF INCREASE OF
PRECIPITATION FOCUS FOR CALIFORNIA BY THE WEEKEND, WITH SOME
MOISTURE POSSIBLY COMING INTO THE SOUTHWEST THEREAFTER. THE PACIFIC
NORTHWEST MAY SEE SOME LIGHT PRECIPITATION THIS WEEKEND OR NEAR THE
START OF THE COMING WEEK WITH THE UPPER TROUGHING. THE LATEST
GUIDANCE MAINTAINS CONSENSUS FOR A FASTER PROGRESSION ACROSS THE
NORTHERN TIER, POTENTIALLY BRINGING A FRONTAL SYSTEM AND SOME
RAINFALL TO THE GREAT LAKES/OHIO VALLEY/NORTHERN MID-ATLANTIC BY
SUNDAY OR MONDAY.
ABOVE SEASONAL NORMAL TEMPERATURES WILL SPREAD INTO THE PLAINS FROM
THE WEST INTO THE WEEKEND DURING WHICH THE DAILY VALUES WILL BE 10-20F
ABOVE NORMAL OVER THE WEST THROUGH FRIDAY, INCREASING TO 15-25F
ABOVE NORMAL OVER THE NORTHERN-CENTRAL PLAINS AND VICINITY DURING
THE WEEKEND. SOME OF THIS WARMTH WITH LESSER ANOMALIES WILL LIKELY
SPREAD INTO THE EAST BY SUNDAY-MONDAY. MEANWHILE, ONGOING CHANGES
FOR THE EAST PACIFIC SYSTEM MOVING INTO THE WEST HAVE LED TO BELOW
NORMAL HIGHS BECOMING MORE CONFINED TO CALIFORNIA AND THE SOUTHWEST
DURING THE WEEKEND WHILE SOME DEGREE OF UPPER TROUGHING REACHING
THE NORTHWEST MAY BRING SLIGHTLY BELOW NORMAL READINGS TO THAT
REGION BY SUNDAY OR MONDAY. THE COLD FRONT PUSHING THROUGH THE EAST
LATE THIS WEEK WILL BRING UNSEASONABLY WARM OVERNIGHT LOWS IN THE
WARM SECTOR FOLLOWED BY A BRIEF COOLER PERIOD (ESPECIALLY OVER THE
APPALACHIANS ON FRIDAY).
CAMPBELL/RAUSCH
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