886
FXUS02 KWBC 090705
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
204 AM EST SAT MAR 09 2024
VALID 12Z TUE MAR 12 2024 - 12Z SAT MAR 16 2024
..HEAVY RAINFALL POTENTIAL RETURNS TO THE SOUTH LATE NEXT WEEK
..OVERVIEW
THE MEDIUM RANGE PERIOD STARTS TUESDAY WITH ONE SHORTWAVE MOVING
THROUGH THE CENTRAL U.S. AS THE NEXT ONE ENTERS THE WEST COAST.
AFTER THIS, THE PATTERN LOOKS TO TREND MUCH MORE AMPLIFIED WITH
UPPER RIDGING BUILDING OVER THE EAST COAST ALLOWING FOR THE SECOND
SYSTEM OVER THE WEST TO DIG SOUTHWARD INTO THE SOUTHWEST. GUIDANCE
SHOWS GENERAL AGREEMENT ON A DEEP CLOSED LOW DEVELOPING OVER THE
SOUTHWEST/FOUR CORNERS REGION ON THURSDAY, AND LINGERING OR ONLY
VERY SLOWLY MOVING EASTWARD INTO THE WEEKEND. THIS SHOULD PROMOTE
A PERIOD OF HEAVY RAINFALL POTENTIAL ACROSS PARTS OF THE SOUTHERN
U.S. LATE THIS WEEK. ELSEWHERE, NORTHERN STREAM ENERGY WILL SLIDE
ACROSS THE UPPER MIDWEST/GREAT LAKES LATE WEEK, AS A STRONG RIDGE
SHIFTS OVER THE WEST COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE VERY LARGE
SCALE PATTERN EVOLUTION DURING THE PERIOD, BUT SOME SIGNIFICANT
DETAILS STILL IN THE DETAILS AND TIMING OF INDIVIDUAL SYSTEMS.
RIGHT OUT OF THE GATE, YESTERDAYS 12Z AND 18Z GFS RUNS WERE FASTER
THAN CONSENSUS WITH THE SHORTWAVE THROUGH THE CENTRAL U.S., BUT
TONIGHT'S 00Z RUN (AVAILABLE AFTER FORECAST GENERATION TIME)
TRENDED SLOWER. THE GFS WAS ALSO MUCH STRONGER WITH INITIAL ENERGY
INTO THE WEST COAST MID WEEK WHICH MOVES ACROSS THE NORTH-CENTRAL
U.S., WITH FAIRLY DECENT SURFACE LOW PRESSURE TRACKING THROUGH THE
MIDWEST LATER THIS WEEK. THE REST OF THE GUIDANCE IS MORE SUBDUED
WITH THIS ENERGY SHOWING ONLY A WAVE OF LOW PRESSURE ALONG THE
ASSOCIATED FRONTAL BOUNDARY. ENERGY ON THE BACKSIDE OF THE MEAN
TROUGH SHOULD THEN DIG SOUTHWARD EVENTUALLY WITH A CLOSED LOW OVER
THE SOUTHWEST/FOUR CORNERS REGION WHILE AT THE SAME TIME NORTHERN
STREAM ENERGY SHIFTS ACROSS THE NORTHERN PLAINS/UPPER GREAT LAKES.
THERE ARE STILL SOME VERY NOTABLE DIFFERENCES IN THE
DETAILS/PLACEMENT OF THIS SYSTEM AND ALSO HOW MUCH PHASING THERE
IS (OR IS NOT) WITH THE NORTHERN STREAM ENERGY. ALSO UNCERTAINTY
ON HOW QUICKLY THE UPPER LOW EJECTS EASTWARD NEXT WEEKEND.
THE WPC BLEND FOR TONIGHT USED A GENERAL MODEL BLEND FOR DAYS 3
AND 4 (USING THE 12Z GFS OVER THE 18Z GFS AS IT LOOKED MORE
REASONABLE THAN THE 18Z/00Z RUNS WITH SHORTWAVE ENERGY THROUGH THE
MIDWEST). FOR DAYS 5-7, INCORPORATED MORE AND MORE OF THE ENSEMBLE
MEANS TO ACCOUNT FOR THE LATE PERIOD UNCERTAINTIES. MAINTAINED
GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
WESTERN U.S. REMAINS UNSETTLED EARLY WEEK AS A COUPLE OF
SHORTWAVES BRING ROUNDS OF RAIN AND HIGHER ELEVATION SNOW
INITIALLY SHIFTING MORE INLAND INTO THE CENTRAL ROCKIES WITH TIME.
RAINFALL SHOULD ALSO BEGIN TO INCREASE IN COVERAGE AND INTENSITY
OVER THE PLAINS AND MISSISSIPPI VALLEY BY WEDNESDAY AS TROUGHING
AMPLIFIES OVER THE WEST. CURRENTLY, NO AREAS ARE DEPICTED ON THE
DAYS 4 AND 5 EXCESSIVE RAINFALL OUTLOOKS. THEN, MOISTURE STREAMING
AHEAD OF THE CLOSED LOW DEVELOPING OVER THE SOUTHWEST SHOULD
INCREASE THE THREAT FOR HEAVY RAIN AND POTENTIALLY FLASH FLOODING
ACROSS THE LOWER MISSISSIPPI VALLEY/GULF COAST/SOUTHEAST NEXT
THURSDAY AND FRIDAY. AREAS ACROSS THE SOUTH MAY BE MORE
SUSCEPTIBLE TO FLOODING WITH THIS SYSTEM CONSIDERING RECENT HEAVY
RAINS. SOME THREAT FOR LOCALLY HEAVY RAIN/MOUNTAIN SNOWS WILL
EXIST ACROSS THE SOUTHWEST AS WELL IN ASSOCIATION WITH THIS
SYSTEM.
MEAN RIDGING ALOFT OVER THE EAST-CENTRAL AND EASTERN U.S. WILL
SUPPORT AN EXPANDING AREA OF ABOVE NORMAL TEMPERATURES TO THE EAST
OF THE ROCKIES. THE CORE OF WARMEST ANOMALIES SHOULD COVER PARTS
OF THE NORTHERN PLAINS AND UPPER MIDWEST TUESDAY THROUGH
WEDNESDAY, WITH HIGHS POTENTIALLY REACHING 20-30 DEGREES ABOVE
NORMAL. ABOVE NORMAL TEMPERATURES WILL GRADUALLY EXPAND INTO THE
SOUTH AND EAST MID TO LATE NEXT WEEK WEEK. OVER THE WEST, THE
WET/SNOWY PATTERN OVER NORTHERN-CENTRAL WEST COAST AND EVENTUALLY
INTO THE ROCKIES WILL MAINTAIN MODERATELY BELOW AVERAGE HIGHS AND
NEAR/ABOVE AVERAGE LOWS THROUGH EARLY NEXT WEEK. UPPER TROUGHING
THAT AMPLIFIES INLAND BY WEDNESDAY-THURSDAY SHOULD SPREAD A
BROADER AREA OF COOL DAYTIME HIGHS ACROSS THE WEST WITH
TEMPERATURES BEGINNING TO REBOUND AGAIN ALONG THE IMMEDIATE COAST
NEXT FRIDAY-SATURDAY AS STRONG RIDGING BUILDS IN ALOFT.
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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