015
FXUS02 KWBC 190701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT FRI MAY 19 2023
VALID 12Z MON MAY 22 2023 - 12Z FRI MAY 26 2023
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLES OFFER A REASONABLY SIMILAR MID-LARGER SCALE
PATTERN EVOLUTION ALOFT INTO NEXT WEEK TO INCLUDE SPLIT STREAM
UPPER TROUGHS DUG OVER BOTH THE WEST COAST AND THE EASTERN U.S.
THAT SANDWICH WARMING UPPER RIDGING SET TO WORK OVER THE CENTRAL
U.S. THAT MAY WITH MUCH UNCERTAINTY SPREAD OVER THE MIDWEST LATER
NEXT WEEK. HOWEVER, THERE ARE WIDESPREAD EMBEDDED SMALLER SCALE
IMPULSE DIFFERENCES AND INTERACTIONS. A FAVORED COMPOSITE MODEL
BLEND SHOULD ACT TO MITIGATE THESE DIFFERENCES CONSISTENT WITH
INDIVIDUAL PREDICTABILITY THROUGH EARLY NEXT WEEK, BUT GROWING
FORECAST SPREAD AND UNCERTAINTY PORTENDS INCREASING USAGE OF THE
MUCH MORE COMPATIBLE GEFS/ECMWF ENSEMBLE MEANS FOR MID-LATER NEXT
WEEK. OVERALL THROUGH THIS FORECAST PERIOD, GUIDANCE DIFFERENCES
SEEM MOST NOTICABLE WITH SURFACE SYSTEM REFLECTION AND LOCAL WARM
SEASON CONVECTION/WEATHER FOCUS, BUT IN PARTICULAR WITH THE
POTENTIAL FOR MODEST TO MODERATE SOUTHEAST U.S. COASTAL LOW
GENESIS AND ASSOCIATED COASTAL TO OFFSHORE RAINFALL. AN OVERALL
GUIDANCE TREND OVER THE PAST FEW CYCLES SEEMS TO GRADUALLY FAVOR
AMPLITUDE AND SHIFT OVER THE WEST ALONG WITH MORE PRONOUNCED
STREAM SEPARATION WITH A RESULTANT SOUTHEAST U.S. UPPER TROUGH
POSITION THAT MAY OFFER MORE OPPORTUNITY FOR COASTAL FRONTAL LOWS
AS ENERGIES ROTATE INTO/AROUND THE SLOW MOVING FEATURE. THIS
OVERALL SOLUTION MAINTAINS BROADLY GOOD WPC PRODUCT CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
A SLOW MOVING/SEPARATED SOUTHEAST U.S. UPPER TROUGH POSITION AND
ASSOCIATED SURFACE FEATURE PROXIMITY SHOULD FOCUS MODER TO LOCALLY
HEAVIER RAINFALL/CONVECTION OVER PORTIONS OF THE SOUTHEAST, BUT
ESPEICALLY WITH WAVE/FRONTAL DEVELOPMENT FROM FLORIDA TO UP THE
SOUTHEAST COAST AND POTENTIALLY THE EASTERN MID-ATLANTIC INTO
MID-LATER WEEK WITH UNCERTAIN COASTAL WAVE DEVELOPMENTS TO
MONITOR. OTHERWISE, THE AFOREMENTIONED UPPER RIDGE POSITION SHOULD
SUPPORT SUMMERTIME TEMPERATURES WITH VALUES UPWARDS TO 15-20
DEGREES ABOVE NORMAL THROUGH EARLY NEXT WEEK SHOULD SHIFT SLOWLY
EAST WITH TIME ACROSS THE NORTHERN PLAINS AND EVENTUALLY THE
MIDWEST LATER NEXT WEEK AS TEMPERED LOCALLY BY SCATTERED AND
POTENTIALLY STRONG THUNDERSTORM ACTIVITY BOTH WITH EJECTION OF
IMPULSES FROM THE WEST AND INTERACTION WITH NORTHERN STREAM
SYSTEM/FRONTAL APPROACHES FROM SOUTHERN CANADA. LOCALLY HEAVY
THUNDERSTORM ACTIVITY MAY FOCUS HEAVY LOCAL DOWNPOURS DOWN OVER
THE SOUTHERN PLAINS AS WELL WITH MOISTURE/INSTABILITY POOLING WITH
SOUTHERN STREAM IMPUSLES. ABOVE TO MUCH ABOVE NORMAL OVERNIGHT
TEMPERATURES AND A PATTERN FAVORING SCATTERED TO WIDESPREAD
SHOWERS AND THUNDERSTORMS ARE ALSO EXPECTED TO LINGER ALL NEXT
WEEK OVER MUCH OF INTERIOR WEST THROUGH THE ROCKIES IN MOISTENED
FLOW CHANNELED BETWEEN WEST COAST UPPER TROUGHING AND THE
DOWNSTREAM CENTRAL U.S. UPPER RIDGE.
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, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
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