852
FXUS02 KWBC 300642
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 AM EDT FRI AUG 30 2024
VALID 12Z MON SEP 02 2024 - 12Z FRI SEP 06 2024
..OVERVIEW
A FAIRLY PROGRESSIVE NORTHERN STREAM UPPER LEVEL PATTERN WILL BE IN
PLACE NEXT WEEK DURING THE MEDIUM RANGE PERIOD. UPPER RIDGING
ACROSS THE SOUTHERN U.S. WILL EXPAND AND BUILD INTO THE WEST AS
SYSTEMS RIDE THE TOP OF THE RIDGE FROM WEST TO EAST, REINFORCING
TROUGHING OVER THE GREAT LAKES AND NORTHEAST. THIS PATTERN SHOULD
PUSH A COUPLE OF WEAKER FRONTAL BOUNDARIES INTO THE CENTRAL AND
SOUTHEASTERN U.S., WITH PERIODS OF STORMY WEATHER EXPECTED TO
ACCOMPANY. MEANWHILE, A PERSISTENT SURFACE TROUGH AND EMBEDDED
WAVES NEAR THE WESTERN GULF COAST SHOULD PROVIDE FOCUS FOR HEAVY
RAINFALL ACROSS PARTS OF TEXAS.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS SHOW FAIRLY GOOD AGREEMENT ON THE OVERALL LARGE SCALE
PATTERN THROUGH MUCH OF NEXT WEEK, WITH THE TYPICAL DIFFERENCES IN
THE DETAILS OF INDIVIDUAL SYSTEMS. MODELS AGREE A COMPACT UPPER LOW
WILL MOVE INTO THE PACIFIC NORTHWEST EARLY WEEK, BUT CONTINUE TO
SHOW VARIABILITY IN HOW THIS INTERACTS WITH ADDITIONAL NORTHERN
STREAM ENERGY PAST THE ROCKIES AND EVENTUAL EFFECTS ON DOWNSTREAM
TROUGHING OVER THE GREAT LAKES TO THE NORTHEAST. THERE IS ALSO
STILL A FAIR AMOUNT OF UNCERTAINTY IN SHORTWAVE ENERGY NEAR THE
TEXAS GULF COAST AS IT MOVES INLAND, WITH SIGNIFICANT IMPACTS TO
HEAVY RAINFALL POTENTIAL ACROSS THAT REGION.
THE WPC FORECAST FOR TONIGHT WAS ABLE TO USE A GENERAL MODEL
COMPROMISE FOR THE FIRST HALF OF THE PERIOD, BUT TRENDED TOWARDS
MAJORITY OF THE ENSEMBLE MEANS BY DAY 7. CONTINUED SOME
INCORPORATION OF THE ECMWF AND GFS LATE PERIOD FOR ADDED SYSTEM
DEFINITION.
..WEATHER/HAZARDS HIGHLIGHTS
THE MAIN HEAVY RAINFALL FOCUS DURING THE PERIOD WILL BE ACROSS THE
SOUTH, PARTICULARLY TEXAS, AS SHORTWAVE ENERGY MOVES INLAND FROM
THE WESTERN GULF. PRECIPITATION COVERAGE AND TOTALS REMAIN HIGHLY
UNCERTAIN, BUT THE OVERALL DYNAMICS AND ANOMALOUS MOISTURE SUPPORT
A HEAVY TO EXCESSIVE RAINFALL THREAT. THIS IS COVERED BY FAIRLY
BROAD MARGINAL RISKS ON THE DAYS 4 AND 5 EROS (COVERING MONDAY TO
TUESDAY NIGHT), WITH A POSSIBLE FOCUS ACROSS THE COAST AND FARTHER
INLAND ACROSS PARTS OF CENTRAL AND WEST TEXAS. INTO THE SOUTHEAST,
MOISTURE ALONG A SAGGING FRONTAL BOUNDARY SHOULD SUPPORT SHOWERS
AND STORMS WITH A MARGINAL RISK OF FLASH FLOODING ON MONDAY.
PRECIPITATION AND LOCALLY HEAVY DOWNPOURS LOOK TO LINGER THE REST
OF THE WEEK ACROSS MUCH OF THE SOUTH, BUT TOTALS AND LOCATIONS ARE
VERY UNCERTAIN. TO THE NORTH, SOME GENERALLY LIGHT PRECIPITATION
SHOULD ACCOMPANY THE SHORTWAVE THROUGH THE WEST INTO THE NORTHERN
PLAINS.
MODESTLY ABOVE NORMAL TEMPERATURES ACROSS THE NORTHWEST ON MONDAY
SHOULD SHIFT EAST AND MODERATE INTO MID WEEK. BY MID TO LATE WEEK,
INCREASING HEAT IS EXPECTED ACROSS MUCH OF THE WEST, WITH MODERATE
TO MAJOR HEATRISK THREATS ACROSS THE SOUTHWEST AND CENTRAL VALLEYS
OF CALIFORNIA. FROM THE SOUTHERN PLAINS TO THE MIDWEST AND THE
EAST, TEMPERATURES SHOULD BE NEAR OR BELOW NORMAL FOR THIS TIME OF
THE YEAR WITHIN A RATHER PLEASANT AIR MASS THROUGH MUCH OF NEXT
WEEK.
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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