143
FXUS02 KWBC 260701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
201 AM EST MON FEB 26 2024
VALID 12Z THU FEB 29 2024 - 12Z MON MAR 04 2024
..HEAVY PRECIPITATION PATTERN EMERGING AGAIN FOR THE WEST
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL AND ENSEMBLE FORECAST SPREAD CONTINUES TO DECREASE THROUGH
MEDIUM RANGE TIME SCALES IN AMPLIFYING UPPER FLOW, BOLSTERING
FORECAST CONFIDENCE. FAVOR A BLEND OF COMPATIBLE GUIDANCE OF THE
GFS/ECMWF/CANADIAN/UKMET FOR THURSDAY INTO SATURDAY, ALBEIT WITH A
BIT MORE WEIGHTING APPLIED TO THE ECMWF/UKMET THAT HAVE PERFORMED
BETTER RECENTLY. PREDICTABILITY SEEMS TO REMAIN AT ABOVE NORMAL
LEVELS LATER WEEKEND INTO EARLY NEXT WEEK AND A COMPOSITE OF THE
GEFS/ECMWF ENSEMBLE MEANS AND BEST COMPATIBLE GFS/ECMWF SEEMS TO
PROVIDE A GOOD FORECAST BASIS ALONG WITH THE NATIONAL BLEND OF
MODELS THROUGH THESE LONGER TIME FRAMES. WPC PRODUCT CONTINUITY IS
WELL MAINTAINED WITH THIS PLAN.
..OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
A LEADING/MAIN SOUTHERN STREAM UPPER TROUGH WITH ORIGINS OVER THE
EAST PACIFIC WILL EJECT EASTWARD FROM NORTHERN MEXICO AND TRAVERSE
THE SOUTH/SOUTHEAST THURSDAY AND FRIDAY AS A SURFACE LOW/FRONTAL
SYSTEM TAKES POSITION OVER THE GULF OF MEXICO. MOISTURE RETURN
FROM THE SOUTHERN GULF AND EASTERLY FETCH FROM THE ATLANTIC ARE
EXPECTED TO FUEL AN AREA WITH RAIN/CONVECTIVE CHANCES. LOCALLY
HEAVY DOWNPOURS MAY FOCUS OVER THE CENTRAL GULF COAST. THIS AREA
WILL MONITORED FOR ANY RUNOFF ISSUES, BUT NO ERO THREAT AREA HAS
BEEN ISSUED AT THIS TIME GIVEN RELATIVELY HIGH FLASH FLOOD
GUIDANCE VALUES. RAIN/SHOWERS WILL LINGER OVER THE SOUTHEAST THIS
WEEKEND WITH MORE, BUT WEAKER IMPULSES IN A SIMILAR PATTERN.
UPSTREAM, THERE CONTINUES TO BE A VERY STRONG GUIDANCE SIGNAL THAT
AN AMPLIFIED UPPER TROUGH DIGGING INTO THE EASTERN PACIFIC LATER
THIS WEEK WILL SHIFT OVER THE WEST THIS WEEKEND. THIS WILL
INCREASINGLY SUPPORT CHANCES FOR A MODERATE TO HEAVIER RAIN FOCUS
INTO THE PACIFIC NORTHWEST MID-LATER WEEK THAT ALONG WITH AN
ASSOCIATED/MODERATE LONG FETCH MOISTURE PLUME WILL SHIFT STEADILY
DOWN THE COAST THROUGH SOUTHERN CALIFORNIA LATER WEEK INTO THE
WEEKEND TO MONITOR. THE WPC DAY 4/THURSDAY AND DAY 5/FRIDAY
EXCESSIVE RAINFALL OUTLOOKS (EROS) OFFER MARGINAL RISK AREAS FOR
COASTAL OREGON THROUGH NORTHERN CALIFORNIA. THERE IS ALSO A
SIGNIFICANT THREAT FOR HIGH WINDS AND HEAVY SNOW TO SPREAD INLAND
ACROSS THE WEST, ESPECIALLY FOR FAVORED TERRAIN/MOUNTAINS AS
HIGHLIGHTED IN THE WPC WINTER WEATHER OUTLOOK. HOWEVER, VALLEY
SNOWFALLS WILL DEVELOP MORE OVER TIME AS SNOW LEVELS DECREASE WITH
UPPER SYSTEM AND WAVY FRONTAL TRANSLATION. THIS TRANSLATION SHOULD
ALSO FAVOR DEVELOPMENT OF AN EMERGING PRECIPITATION SHIELD OVER
THE COOLING ROCKIES/PLAINS BY SUNDAY/NEXT MONDAY THAT MAY INCLUDE
SNOWS ON THE NORTHWEST PERIPHERY OF ACTIVITY.
UPPER TROUGH AMPLIFCIATION AND INLAND MARCH BY THE WEEKEND WILL
COOL TEMPERATURES OVER MUCH OF THE WEST, LEADING TO MAXIMUM VALUES
OF AS MUCH AS 10-15 DEGREES BELOW NORMAL. DOWNSTREAM, EXPECT MUCH
ABOVE NORMAL PRE-FRONTAL WARMTH LATER WEEK OVER THE NORTH-CENTRAL
U.S. THAT WILL SPREAD TO MUCH OF THE CENTRAL AND EASTERN U.S. THIS
WEEKEND/EARLY NEXT WEEK DOWNSTREAM OF THE MAIN UPPER TROUGH/LEAD
FRONTAL SYSTEM WORKING OVER THE WEST. SPRING MAXIMUM TEMPERATURES
RANGING UPWARDS TO 20-30 DEGREES ABOVE NORMAL WILL SPREAD FROM THE
MIDWEST TOWARD THE NORTHEAST TO OFFER POTENTIAL FOR SOME RECORD
VALUES.
SCHICHTEL
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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