593
FXUS02 KWBC 261917
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
317 PM EDT TUE MAR 26 2024
VALID 12Z FRI MAR 29 2024 - 12Z TUE APR 02 2024
...ROUNDS OF HEAVY RAIN AND HIGH ELEVATION SNOW LIKELY ACROSS
CALIFORNIA, THE GREAT BASIN, AND THE CENTRAL/SOUTHERN ROCKIES...
..OVERVIEW
SNOW AND RAIN MAY CONTINUE FRIDAY IN MAINE AS A LOW PRESSURE
SYSTEM IS SLOW TO EXIT. MEANWHILE, AN UPPER LOW IS FORECAST TO
SLOWLY MOVE DOWN THE CALIFORNIA COAST LATE FRIDAY THROUGH SUNDAY
BEFORE SLOWLY TRACKING OVER THE SOUTHWEST INTO THE MIDDLE OF NEXT
WEEK. THIS FEATURE AND ITS SURFACE LOW WILL DIRECT MOISTURE INTO
CALIFORNIA AND PRODUCE HEAVY RAIN AND HIGHER ELEVATION SNOW FOR
CALIFORNIA, MUCH OF THE SOUTHWEST/GREAT BASIN AND CENTRAL/SOUTHERN
ROCKIES. FARTHER DOWNSTREAM, INCREASING MOISTURE SHOULD COMBINE
WITH NORTHERN STREAM TROUGHING TO PRODUCE LOW PRESSURE THAT TRACKS
EAST FROM THE CENTRAL PLAINS SUNDAY THROUGH THE NORTHEAST TUESDAY.
EXPANSIVE PRECIPITATION COVERAGE IS LIKELY WITH THIS SYSTEM WITH
SNOW AND FREEZING RAIN POSSIBLE ON THE NORTH SIDE OF THE SYSTEM.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z/06Z DETERMINISTIC GUIDANCE WERE IN GOOD AGREEMENT WITH THE
LOW/TROUGH IN THE SOUTHWEST AND BROAD RIDGE OVER SOUTHEAST/NORTHERN
TIER SHORTWAVE ACTIVITY THROUGH SUNDAY. IN PARTICULAR, THE 00Z
ECMWF/06Z GFS ARE SIMILAR WITH THE CA LOW AND ITS REINFORCING
TROUGH ON SUNDAY THAT ALLOWS SOME EASTWARD MOVEMENT TO BEGIN WHILE
THE 00Z CMC/UKMET WERE MORE CLOSED. HOWEVER, THE 12Z RUNS ARE IN
BETTER AGREEMENT WITH A LESS CLOSED SYSTEM BY SUNDAY.
THE WPC FORECAST WAS BASED ON A MULTI-MODEL BLEND FAVORING THE
00Z/06Z EC/GFS UNTIL DAY 5 WHEN SOME ENSEMBLE MEANS BEGAN TO BE
INCLUDED.
..WEATHER/HAZARDS HIGHLIGHTS
SURFACE LOW PRESSURE IN THE WESTERN ATLANTIC TRACKING TOWARD THE
CANADIAN MARITIMES WILL CAUSE RAIN/SNOW TO LINGER ACROSS MAINE
THROUGH FRIDAY.
FOR THE WESTERN U.S., AN ACTIVE AND UNSETTLED PERIOD IS EXPECTED
AS A PERSISTENT JET ON THE SOUTHEAST SIDE OF AN UPPER LOW DIRECTS
MOISTURE INTO CALIFORNIA EASTWARD. A MODEST ATMOSPHERIC RIVER
SHOULD START TO TAKE AIM AT CALIFORNIA LATE FRIDAY WITH HEAVY RAIN
AHEAD OF THE ASSOCIATED COLD FRONT. THE TIMING OF THIS FRONT IS A
BIT SOONER THAN PREVIOUS, SO A DAY 4 SLIGHT RISK HAS BEEN RAISED
FOR PORTIONS OF SANTA BARBARA AND VENTURA COUNTIES. OTHERWISE THE
DY 4 MARGINAL RISK LOOKS TO BE IN GOOD SHAPE FROM COASTAL
CALIFORNIA TOWARD THE FOOTHILLS OF THE SIERRA NEVADA. THE HIGHER
ELEVATIONS OF THE SIERRA NEVADA CAN EXPECT HEAVY SNOW. BY
SATURDAY, ANOMALOUS MOISTURE LIKELY REACHING ABOVE THE 95TH
PERCENTILE CONTINUES TO BE DIRECTED AT SOUTHERN CALIFORNIA.
NOTABLE UPSLOPE FLOW INTO THE TRANSVERSE RANGES MEANS HEAVY
RAINFALL COULD OCCUR, SO A SLIGHT RISK IS CONTINUED FOR UPSLOPE
PORTIONS OF THE TRANSVERSE RANGE BELOW THE SNOWY HIGHER ELEVATIONS.
THE MARGINAL RISK IS EXPANDED FARTHER EAST THROUGH SOUTHERN NEVADA
AS TIMING OF AS MOISTURE SPREADING EAST HAS ALSO BECOME EARLIER.
AMPLE MOISTURE REMAINS IN PLACE INTO SUNDAY- MONDAY ACROSS MUCH OF
CALIFORNIA INTO THE DESERT SOUTHWEST AND GREAT BASIN AND INTO THE
ROCKIES. MODERATE TO HEAVY SNOW IS LIKELY IN THE HIGHER ELEVATIONS
OF THE INTERMOUNTAIN WEST.
FARTHER EAST, SHORTWAVES GENERALLY RIDING ALONG THE NORTHERN SIDE
OF A CENTRAL U.S. RIDGE COULD COMBINE WITH MOISTURE TO PRODUCE SOME
LIGHT TO MODERATE PRECIPITATION FRIDAY INTO THE WEEKEND ACROSS THE
NORTH-CENTRAL U.S. AND GREAT LAKES REGION INTO OHIO VALLEY AND
NORTHERN MID-ATLANTIC. HEAVIER PRECIP IS LIKELY TO DEVELOP WITH A
LOW PRESSURE SYSTEM TRACKING EAST FROM THE CENTRAL PLAIN THROUGH
THE NORTHEAST SUNDAY-TUESDAY. CHANCES FOR WINTRY PRECIPITATION ARE
INCREASING ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST BY THE
WEEKEND, AND STRETCHING INTO THE GREAT LAKES REGION AND HIGHER
ELEVATIONS OF THE NORTHEAST BY MONDAY.
CHILLY TEMPERATURES LINGER ACROSS THE NORTH-CENTRAL U.S. THROUGH
MONDAY, BUT FARTHER SOUTH FROM THE CENTRAL TO SOUTHERN
PLAINS/MISSISSIPPI VALLEY, NOTABLE WARMTH IS EXPECTED LATE WEEK
INTO THE WEEKEND AS UPPER RIDGING BUILDS. TEMPERATURES OF 10-20
DEGREES ABOVE AVERAGE WILL BECOME WIDESPREAD, WITH HIGHS IN THE 70S
AND 80S REACHING KANSAS AND MISSOURI WHILE HIGHS CLIMB INTO THE
90S IF NOT 100F IN SOUTHERN TEXAS. THE ABOVE NORMAL TEMPERATURES
ARE LIKELY TO EXPAND EAST INTO THE OHIO/TENNESSEE VALLEYS, MID-
ATLANTIC, AND SOUTHEAST BY EARLY NEXT WEEK. A COLD FRONT IS
FORECAST TO FINALLY DROP TEMPERATURES IN THE SOUTH-CENTRAL U.S. BY
TUESDAY, FOCUSING THIS WARMTH IN THE SOUTHEAST. MEANWHILE IN THE
WEST, NEAR TO ABOVE NORMAL LOWS BUT NEAR TO BELOW NORMAL HIGHS ARE
FORECAST, CONSISTENT WITH THE CLOUDS AND PRECIPITATION THERE. ONE
EXCEPTION MAY BE OVER THE PACIFIC NORTHWEST WHERE ENOUGH UPPER
RIDGING SHOULD BUILD IN TO PUSH HIGHS A ABOVE NORMAL SATURDAY
THROUGH EARLY NEXT WEEK.
JACKSON
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
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