929
FXUS02 KWBC 121903
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 PM EDT FRI JUL 12 2024
VALID 12Z MON JUL 15 2024 - 12Z FRI JUL 19 2024
...HAZARDOUS TO DANGEROUS HEAT FOR PARTS OF THE CENTRAL TO EASTERN
U.S. EARLY NEXT WEEK. HIGH HEAT BUILDS OVER THE WEST NEXT WEEK...
..OVERVIEW
UPPER LEVEL RIDGING WILL BE IN PLACE NEXT WEEK ACROSS THE SOUTHERN
HALF OF THE COUNTRY TO BRING ABOVE NORMAL TO HAZARDOUS
TEMPERATURES TO MUCH OF THE NATION. UPPER TROUGH DEVELOPMENT OFF
THE WEST COAST LATE NEXT WEEK MAY ACT TO BUILD UPPER RIDGING OVER
THE WEST. THIS WOULD ALLOW ENERGIES DIGGING TO THE LEE TO
INCREASINGLY WORK INTO DOWNSTREAM RIDGING OVER THE SOUTH.
MEANWHILE, A SERIES OF POTENT UPPER LEVEL SHORTWAVES WILL SWING
ACROSS THE UPPER MIDWEST, GREAT LAKES, AND NORTHEAST, AND A COUPLE
OF TEMPERATURE MODERATING FRONTAL BOUNDARIES WILL SINK SOUTH ACROSS
THE NORTH-CENTRAL U.S. AND THE NORTHEAST, WITH POTENTIAL TO SINK
DOWN INTO THE SOUTH/SOUTHEAST LATER PERIOD. PRECIPITATION CHANCES
WILL INCREASE ALONG THESE FRONTAL BOUNDARIES, AND DAILY
PRECIPITATION CHANCES WILL ALSO EXIST IN THE FOUR CORNERS REGION AS
MONSOONAL MOISTURE FOCUSES OVER THE AREA.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST MODELS AND ENSEMBLES CONTINUE TO SHOW OVERALL GOOD
AGREEMENT ON THE LARGE SCALE PATTERN THROUGH MUCH OF THE PERIOD,
WITH TYPICAL SMALLER SCALE DETAILS NEEDING MORE TIME TO BE FULLY
RESOLVED. MAIN SYSTEM DIFFERENCES ARISE BY LATE PERIOD WITH
AMPLITUDE AND TIMING OF THE TROUGH SINKING SOUTHWARD THROUGH THE
EAST, WITH THE LAST FEW RUNS OF THE GFS OFFERING A MORE SOUTHWARD
PUSH INTO THE SOUTH-CENTRAL STATES (AS A RESULT OF SLIGHTLY
STRONGER RIDGING OVER THE WESTERN ATLANTIC/SOUTHEAST).
WPC PROGS FOR TODAY USED A BLEND OF THE LATEST DETERMINISTIC
MODELS (WITH A SLIGHT WEIGHTING TOWARDS THE ECMWF) FOR THE FIRST
HALF OF THE PERIOD, TRENDING MORE TOWARDS THE ENSEMBLE MEANS LATER
NEXT WEEK. THIS MAINTAINED GOOD CONTINUITY WITH PREVIOUS WPC
FORECASTS AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
MONSOONAL MOISTURE WILL FOCUS OVER PORTIONS OF THE FOUR CORNERS
REGION, WHICH WILL ALLOW FOR DAILY ROUNDS OF PRECIPITATION THAT
COULD RESULT IN FLASH FLOODING, ESPECIALLY NEAR STEEP TERRAIN AND
BURN SCARS. A MARGINAL RISK OF EXCESSIVE RAINFALL REMAINS PLANNED
FOR DAY 4 (MONDAY) AND DAY 5 (TUESDAY) FOR MUCH OF THE FOUR CORNERS
REGION AND PORTIONS OF THE SOUTH-CENTRAL ROCKIES IN A REGION WITH
PROTRACTED FAVORABLE UPPER DIFFLUENCE, WITH SOME FOCUS ALSO
SPILLING INTO THE CENTRAL HIGH PLAINS AND SOUTHWEST TEXAS.
ACROSS THE GREAT LAKES AND NORTHEAST, UPPER LEVEL SHORTWAVES AND
WELL DEFINED AND WAVY SURFACE FRONTS WILL PROVIDE SUPPORT FOR
MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS. WITH AMPLE MOISTURE
AND INSTABILITY IN PLACE ACROSS THESE REGIONS, LOCALLY HEAVY
RAINFALL WILL BE POSSIBLE AND MAY LEAD TO ISOLATED INSTANCES OF
FLASH FLOODING. A WPC MARGINAL RISK OF EXCESSIVE RAINFALL OUTLOOK
(ERO) REMAINS IN PLACE FOR THE GREAT LAKES AND NORTHEAST ON DAY 4
(MONDAY), ESPECIALLY GIVEN THE HEIGHTENED SENSITIVITY IN THE
NORTHEAST FOLLOWING HEAVY RAINS THIS WEEK. THE STORM PREDICTION
CENTER ALSO HIGHLIGHTS MIDWEST PARTS OF THIS REGION FOR SOME SEVERE
WEATHER. A DAY 5 (TUESDAY) MARGINAL RISK ERO HAS ALSO BEEN
INTRODUCED DOWN ACROSS THIS REGION AND INTO THE OHIO AND MID-
MISSISSIPPI VALLEYS/CENTRAL PLAINS AS THE MAIN FRONTAL ZONE SHIFTS
SOUTHEASTWARD.
ELSEWHERE, PRECIPITATION CHANCES WILL PROGRESS FURTHER SOUTHWARD
ACROSS MUCH OF THE REST OF THE CENTRAL AND EASTERN U.S. MID-NEXT
WEEK AS A COLD FRONT MOVES SOUTH, AND DAILY PRECIPITATION CHANCES
WILL PERSIST IN FLORIDA WITH SUMMERTIME CONVECTION. LOCALLY HEAVY
RAIN WILL BE POSSIBLE IN THESE AREAS WITH ANY HEAVIER THUNDERSTORM
ACTIVITY. THE WEST COAST AND MUCH OF THE PACIFIC NORTHWEST WILL
REMAIN MAINLY DRY THROUGH NEXT WEEK. HEAVY RAINFALL MAY RETURN TO
PARTS OF THE MID-ATLANTIC MID TO LATER NEXT WEEK AS THE FRONTAL
BOUNDARY IS SLOWER TO MOVE THROUGH THAT REGION.
MUCH OF THE NATION WILL EXPERIENCE ABOVE AVERAGE TEMPERATURES NEXT
WEEK AND A THREAT FOR WIDESPREAD RECORD VALUES WHILE BECOMING
DANGEROUSLY HOT FOR MANY FROM ESPECIALLY THE CENTRAL TO EASTERN
U.S.. HAZARDOUS HEAT SHOULD SLOWLY SUPPRESS SOUTH AND EASTWARD WITH
TIME AS AMPLIFIED TROUGHING DIPS INTO THE GREAT LAKES AND
NORTHEAST/MID- ATLANTIC. TEMPERATURES IN THE 110S ARE LIKELY TO
CONTINUE ACROSS THE DESERT SOUTHWEST, AND HIGHS NEAR OR ABOVE 100
WILL BE COMMON IN THE CENTRAL/SOUTHERN PLAINS. TEMPERATURES ACROSS
THE NORTHWEST MAY BE MARGINALLY ABOVE NORMAL THROUGH EARLY NEXT
WEEK, BUT AS UPPER RIDGING BUILDS BACK IN, ANOMALIES TICK UPWARD
AGAIN IN A PATTERN WITH INCREASING HOT CONDITIONS OVER THE WEST.
SANTORELLI/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 (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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