913
FXUS02 KWBC 031917
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
317 PM EDT WED JUL 3 2024
VALID 12Z SAT JUL 06 2024 - 12Z WED JUL 10 2024
***MAJOR HEATWAVE EXPECTED FOR THE LOWER ELEVATIONS OF CALIFORNIA
AND THE DESERT SOUTHWEST INTO NEXT WEEK, AND BERYL EVENTUALLY
HEADED FOR THE WESTERN GULF COAST***
..OVERVIEW
AN INTENSE AND PROLONGED HEATWAVE IS FORECAST TO IMPACT MUCH OF
CALIFORNIA AND EXTENDING INTO THE LOWER ELEVATIONS OF THE DESERT
SOUTHWEST THROUGH THE MIDDLE OF NEXT WEEK. MEANWHILE, THE TRACK AND
INTENSITY OF TROPICAL CYCLONE BERYL WILL BEAR WATCHING AS IT COULD
BE MOVING CLOSE TO OR OVER SOUTHERN TEXAS BY EARLY NEXT WEEK. A
LOW PRESSURE SYSTEM IS FORECAST TO CROSS THE NORTHERN GREAT LAKES
WITH A TRAILING FRONT ACROSS THE EASTERN U.S., WITH SHOWERS AND
STORMS FIRING SOUTH OF THE BOUNDARY ACROSS PORTIONS OF THE
SOUTHERN PLAINS AND EXTENDING EAST TO THE OHIO VALLEY AND THE MID-
ATLANTIC REGION. HOT AND HUMID CONDITIONS WILL ALSO CONTINUE FOR
MUCH OF THE SOUTHERN STATES AND EXTENDING TO THE EAST COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO FAVOR MEAN TROUGHING TO DIP INTO THE
MID-SECTION OF THE COUNTRY WHILE AN ANOMALOUSLY STRONG UPPER RIDGE
WITH HEIGHTS POSSIBLY REACHING 600DM REMAINS ANCHORED OVER THE
WEST COAST. THE GUIDANCE SUGGESTS THIS RIDGE SHOULD DRIFT SLIGHTLY EAST
OVER THE SOUTHERN INTERMOUNTAIN WEST BY NEXT TUESDAY/WEDNESDAY.
THE MODEL CONSENSUS HAS CONTINUED TO TREND MORE AMPLIFIED IN THIS
OVERALL PATTERN WITH THE RIDGE EXTENDING MORE TO THE NORTH INTO
WESTERN CANADA. MEANWHILE, PERIODIC SHORTWAVE ENERGY DIPPING TOWARD
THE BASE OF THE MEAN TROUGH WILL HAVE IMPLICATIONS ON HOW FAR
NORTH TROPICAL CYCLONE BERYL WILL TRACK TOWARD THE WESTERN GULF
COAST REGION. THE ECMWF, WHICH HAS BEEN THE LEFT-MOST TRACK
GUIDANCE FOR BERYL, HAS CONTINUED TO SHIFT BERYL'S TRACK MORE
NORTHWESTWARD TOWARD SOUTHERN TEXAS TO BETTER AGREE WITH THE GFS.
SUBTLE MUTUAL INTERACTION BETWEEN THE MEAN TROUGH AND THE
CIRCULATION OF BERYL TOGETHER WITH THE UNCERTAIN DISTANCE BETWEEN
THE TWO SYSTEMS CONTINUE TO INTRODUCE A HIGHER DEGREE OF FORECAST
UNCERTAINTY OVER THE VICINITY OF THE WESTERN GULF COAST REGION FOR
EARLY NEXT WEEK. A TROPICAL WAVE BEHIND BERYL COULD INTRODUCE
ADDITIONAL FORECAST UNCERTAINTY IN THIS REGION BY THE MIDDLE OF
NEXT WEEK AS SOME MODELS SUGGEST THIS WAVE WILL DEVELOP OVER THE
WESTERN GULF OF MEXICO BEHIND BERYL.
LATEST MODEL GUIDANCE ALSO TRENDS TOWARD A FASTER EASTWARD
PROGRESSION OF UPPER TROUGHING ACROSS THE GREAT LAKES TOWARD NEW
ENGLAND FROM EARLY TO MIDWEEK NEXT WEEK.
THE WPC MEDIUM-RANGE FORECASTS WERE BASED ON 40% FROM THE 00Z
ECMWF/EC MEAN, 40% FROM THE 06Z GFS/GEFS, AND 20% FROM THE 00Z
CMC/CMC MEAN, WITH A HIGHER PERCENTAGE FROM THE ENSEMBLE MEANS FOR
DAYS 6 AND 7.
..WEATHER/HAZARDS HIGHLIGHTS
ON SATURDAY, THERE IS ENOUGH OF A MODEL SIGNAL TO MAINTAIN THE
MARGINAL RISK AREA FOR PORTIONS OF THE MID-ATLANTIC, WHERE SOME
STRONG THUNDERSTORMS WITH HEAVY RAIN RATES COULD DEVELOP QUICKLY IN
THE VICINITY OF THE COLD FRONT WITH ITS FORWARD MOTION SLOWING
DOWN. THIS IS ALSO EXTENDED TO THE NORTH TO INCLUDE PARTS OF NEW
ENGLAND WHERE SOME HEAVY DOWNPOURS WILL ALSO BE POSSIBLE.
MEANWHILE, SOME OF THE OUTER RAIN BANDS OF BERYL, FORECAST TO RE-
INTENSIFY TO A HURRICANE, COULD BE APPROACHING SOUTHERN TEXAS BY
LATE SATURDAY AND INTO EARLY SUNDAY, WHEN THE HEAVIEST RAINFALL
WILL MOST LIKELY BE JUST OFF THE COAST.
GOING INTO THE DAY 5 PERIOD SUNDAY, THE OFFICIAL NHC TRACK OF BERYL
HAS IT GETTING CLOSE TO BROWNSVILLE, TEXAS, ALTHOUGH THERE IS STILL
CONSIDERABLE UNCERTAINTY IN WHERE IT COULD ULTIMATELY GO. GIVEN THE
FORECAST TRACK, RAIN AND EMBEDDED THUNDERSTORMS WOULD BE INCREASING
IN COVERAGE ACROSS DEEP SOUTH TEXAS THROUGH THE DAY SUNDAY, WITH
THE POTENTIAL FOR 3-6 INCH TOTALS BY 12Z MONDAY SOUTH OF CORPUS
CHRISTI. THEREFORE, A SLIGHT RISK AREA IS MAINTAINED FOR THE DAY 5
ERO FOR THIS AREA, AND A BROADER MARGINAL RISK AREA EXTENDING
FARTHER NORTHWARD ALONG THE TEXAS COAST TO ACCOUNT FOR PERIODS OF
HEAVY RAINFALL WITH THE OUTER RAIN BANDS. FARTHER TO THE NORTH
ACROSS THE CENTRAL PLAINS, A MARGINAL RISK AREA IS ALSO MAINTAINED
WHERE SOME MCS ACTIVITY MAY DEVELOP NORTHEAST OF A SURFACE LOW AND
UPPER TROUGH.
A MAJOR HEATWAVE WILL BE ONGOING FOR THE INLAND LOWER ELEVATIONS
OF CALIFORNIA WITH WIDESPREAD 105-115 DEGREE READINGS LIKELY.
READINGS COULD REACH 120 DEGREES AT THE HOTTEST LOCATIONS IN THE
DESERT SOUTHWEST. DAILY TEMPERATURES RECORDS MAY BE TIED OR BROKEN
IN MANY CASES. THE HEAT IS FORECAST TO EXPAND ACROSS INLAND
PORTIONS OF WASHINGTON, OREGON, AND MUCH OF THE INTERMOUNTAIN WEST
FOR THE FIRST HALF OF NEXT WEEK, WITH 100+ DEGREE HIGHS LIKELY FOR
THE LOWER VALLEY LOCATIONS. ELSEWHERE, WIDESPREAD 90S FOR HIGHS CAN
BE EXPECTED FOR MUCH OF THE SOUTHERN U.S. AND EXTENDING EASTWARD TO
THE EAST COAST, ALONG WITH HIGH HUMIDITY MAKING IT FEEL 5-10
DEGREES HOTTER IN MANY CASES.
KONG/HAMRICK
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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