427
FXUS02 KWBC 270647
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
147 AM EST THU FEB 27 2025
VALID 12Z SUN MAR 02 2025 - 12Z THU MAR 06 2025
..COAST TO COAST U.S. SOUTHERN TIER SYSTEM TO MONITOR
..OVERVIEW
THE MEDIUM RANGE PERIOD WILL FEATURE A RATHER PROGRESSIVE UPPER
FLOW PATTERN ACROSS THE LOWER 48 STATES AS A COUPLE OF SYSTEMS
TRAVERSE COAST TO COAST. AMPLIFIED NORTHERN STREAM TROUGHING OVER
THE EAST WILL BE ESTABLISHED THIS WEEKEND, BUT WILL SHIFT EASTWARD
EARLY NEXT WEEK AND BE REPLACED BY UPPER RIDGING. MEANWHILE, A LEAD
SOUTHERN STREAM CUTOFF LOW OVER THE SOUTHERN HIGH PLAINS ON SUNDAY
WILL LIFT NORTH AND EAST AND GET ABSORBED INTO THE LARGER SCALE
FLOW INTO EARLY NEXT WEEK OVER THE SOUTH- CENTRAL U.S.. BEHIND
THIS, A DEEP TROUGH/CLOSED LOW WILL MOVE INCREASINGLY INTO THE WEST
SUNDAY/MONDAY. WEATHER/HAZARD FOCUS WITH THIS EMERGING AND
AMPLIFIED SOUTHERN STREAM SYSTEM WILL TRACK FROM THE SOUTHWEST
THROUGH THE SOUTH-CENTRAL THEN INTO THE EAST BY THE MIDDLE OF NEXT
WEEK. THE GUIDANCE SIGNAL HAS GROWN FOR AN ASSOCIATED AND
INCREASINGLY WIDESPREAD SWATH OF WINDY AND WET/UNSETTLED WEATHER TO
MONITOR IN THESE AREAS. A THIRD AMPLIFIED TROUGH APPROACHES THE
WEST COAST NEXT THURSDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLES THIS CYCLE ARE SHOWING BETTER CLUSTERING FOR
BOTH THE INITIAL CUT OFF LOW OVER THE SOUTHERN HIGH PLAINS, AND THE
NEXT TROUGH INTO THE WEST ON SUNDAY-MONDAY. THERE ARE SOME
LINGERING DIFFERENCES IN THE EXACT POSITIONING OF THE LOW AND
TIMING, WHICH COULD HAVE SENSIBLE WEATHER IMPACTS, PARTICULARLY IN
PLACEMENT OF RAINFALL OVER THE SOUTHERN PLAINS. THESE DETAILS
THOUGH MAY TAKE UNTIL THE SHORT RANGE TO FULLY IRON OUT. THE UKMET
WAS NOTABLY SOUTH OF CONSENSUS WITH THE TROUGH ACROSS THE WEST INTO
MONDAY, SO IT WAS NOT USED IN THE FORECAST BLEND TONIGHT. THERE IS
BETTER CONSISTENCY AND CLUSTERING BETWEEN THE GFS, ECMWF, AND CMC
AS THE SHORTWAVE LIFTS INTO THE UPPER MIDWEST/GREAT LAKES MID NEXT
WEEK. A THIRD DEEP TROUGH APPROACHES THE WEST COAST NEXT WEDNESDAY
INTO THURSDAY, BUT DOES SLOW A LOT OF RUN TO RUN AND MODEL TO MODEL
VARIABILITY.
THE WPC FORECAST BLEND FOR TONIGHT CONSISTED OF THE GFS, ECMWF,
AND CMC FOR THE FIRST HALF OF THE PERIOD. GRADUALLY TRANSITIONED TO
60 PERCENT OF THE ENSEMBLE MEANS BY THE END OF THE PERIOD,
PRIMARILY TO ADDRESS THE LATE PERIOD UNCERTAINTY OVER THE WEST
COAST. USED THE EC AND CMC TO COMPLIMENT THE ENSEMBLE MEANS AS
WELL.
..WEATHER/HAZARDS HIGHLIGHTS
THE SOUTHERN STREAM UPPER LOW MOVING INTO THE SOUTHERN PLAINS ON
SUNDAY MAY LEAD TO INCREASING MOISTURE FOR THIS REGION. THIS ALSO
HAS A HIGH WIND THREAT ACROSS THAT BROAD AREA. THERE ALSO APPEARS
TO BE A BETTER SIGNAL FOR THE PRECIPITATION TO SPREAD FARTHER
EAST/NORTHEAST ACROSS THE SOUTHERN PLAINS AND EASTWARD EARLY NEXT
WEEK. THE NORTHERN STREAM TROUGH MOVING THROUGH THE EASTERN PACIFIC
AND INTO THE WEST NEXT WEEKEND WILL ALSO BRING PRECIPITATION
CHANCES BACK FOR THE WEST COAST, AND SPREADING ACROSS THE GREAT
BASIN/ROCKIES. AS THIS TROUGH MOVES INTO THE CENTRAL U.S. AROUND
TUESDAY-WEDNESDAY NEXT WEEK, IT SHOULD TAP MOISTURE FROM THE GULF
TO FUEL MORE WIDESPREAD RAINS ACROSS THE EASTERN HALF OF THE U.S..
SPC ALSO HIGHLIGHTS A THREAT FOR SEVERE WEATHER OVER THE SOUTH-
CENTRAL STATES GIVEN SUPPORT. THERE IS ALSO THE POTENTIAL FOR
MODERATE TO AT LEAST LOCALLY HEAVY RAINFALL AND WITH AMBIENT MOIST
SOIL CONDITIONS IN SOME AREAS. GUSTY WINDS COULD ACCOMPANY THIS
SYSTEM, DEPENDING ON HOW DEEP THE PARENT SURFACE LOW GETS. ANOTHER
ROUND OF MODERATE RAIN AND ELEVATION SNOW MOVES INTO CALIFORNIA
NEXT WEDNESDAY AHEAD OF THE THIRD SYSTEM.
MUCH ABOVE NORMAL TEMPERATURES OVER THE ROCKIES AND PLAINS STATES
ON SUNDAY WILL GRADUALLY PROGRESS EASTWARD WITH TIME AND MODERATE.
THE GREATEST ANOMALIES, 15 TO 20 DEGREES ABOVE NORMAL, WILL BE
ACROSS THE NORTHERN PLAINS THROUGH MONDAY. TEMPERATURES ACROSS MUCH
OF THE EAST WILL BE CONSIDERABLY COLDER THAN NORMAL ON SUNDAY, BUT
SHOULD MODERATE BACK TO NORMAL MONDAY-TUESDAY, AND WARMER THAN
NORMAL WEDNESDAY. BY NEXT THURSDAY, MUCH OF THE COUNTRY MAY BE NEAR
OR WITHIN A FEW DEGREES OF NORMAL.
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 (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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