670
FXUS02 KWBC 020628
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 AM EDT FRI AUG 2 2024
VALID 12Z MON AUG 05 2024 - 12Z FRI AUG 09 2024
...HAZARDOUS HEAT PERSISTS ACROSS THE SOUTHWEST AS HEAT
INTENSIFIES OVER THE SOUTH-CENTRAL U.S. NEXT WEEK...
...WATCHING TROPICAL THREATS FROM FLORIDA TO THE SOUTHEAST U.S.
COAST NEXT WEEK...
..OVERVIEW
UPPER RIDGING OVER THE WESTERN U.S. THIS WEEKEND WILL BE UP AGAINST
UPPER TROUGHING DIGGING DOWN CENTRAL CANADA TOWARD THE NORTHERN
PLAINS, CAUSING THE RIDGE TO GET SUPPRESSED WITH TIME AND EXTEND
EAST TOWARD THE SOUTH-CENTRAL U.S. NEXT WEEK. THIS PATTERN WILL BE
FAVORABLE IN MAINTAINING THE HEAT ACROSS THE SOUTHWEST WHILE
SPREADING THE HEATWAVE ACROSS THE SOUTH. NORTHERN STREAM FLOW AND
ENERGY DIGGING TO THE LEE OF THE UPPER RIDGE WILL REINFORCE
TROUGHING OVER THE UPPER MIDWEST TO THE EAST THAT LASTS THROUGH THE
MIDDLE OF NEXT WEEK. THE NATIONAL HURRICANE CENTER IS ALSO
MONITORING THE POTENTIAL FOR TROPICAL DEVELOPMENT THAT COULD AFFECT
THE EASTERN GULF COAST AND THEN THE SOUTHEAST U.S. COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THERE IS GENERALLY GOOD AGREEMENT WITH THE LARGE SCALE PATTERN AND
HOW IT EVOLVES OVER THE NEXT WEEK. HOWEVER, NOTICEABLE
UNCERTAINTY IN THE TIMING AND AMPLITUDE OF ENERGIES THROUGH THE
NORTHERN TIER TO CARVE OUT A MIDWEST/EASTERN U.S. MEAN UPPER
TROUGH, ESPECIALLY LATER IN THE PERIOD PERSIST IN THE LAST FEW
RUN MODEL CYCLES. ALSO QUESTION ON THE EXTENT AND STRENGTH OF THE
UPPER RIDGE FROM THE SOUTHWEST INTO THE CENTRAL PLAINS/SOUTHEAST.
MODELS AND ENSEMBLES CONTINUE TO FAVOR POSSIBLE TROPICAL
DEVELOPMENT NEAR/SOUTH OF FLORIDA OVER THE WEEKEND BUT WITH A WIDE
VARIETY OF SOLUTIONS TO THE TRACK OF THE TROPICAL SYSTEM. CONSENSUS
FAVORS TROPICAL CYCLONE DEVELOPMENT TO TRACK EAST-NORTHEAST
NEAR/OFF THE COAST OF THE SOUTHEAST U.S., WHICH REFLECTS THE
NATIONAL HURRICANE CENTER THROUGH DAY 7. ALTHOUGH THE 12Z GFS
DECIDEDLY TURNS THE CYCLONE TOWARD THE EAST- NORTHEAST, THERE IS
STILL QUITE A NUMBER OF THE 12Z GEFS MEMBERS MAINTAINING A WEST-
NORTHWEST TRACK ACROSS THE NORTHEASTERN GULF OF MEXICO. THIS
SYSTEM WILL NEED TO BE WATCHED FOR POSSIBLE HEAVY RAINFALL IMPACTS
TO PARTS OF THE GULF COAST/FLORIDA AND THE SOUTHEAST.
THE WPC MEDIUM RANGE FORECAST SUITE MAINTAINED CONTINUITY BY
UTILIZING A MULTI-MODEL BLEND OF THE OPERATIONAL MODELS AND THEIR
ENSEMBLE MEANS. THE CMC AND WESTWARD- MOVING GFS SOLUTIONS FOR THE
TROPICAL SYSTEM WERE REDUCED/OMITTED WHILE LEANING MORE TOWARDS
THE ENSEMBLE MEANS DAYS 6 AND 7 TO ACCOUNT FOR NORTHERN STREAM
UNCERTAINTIES.
..WEATHER/HAZARDS HIGHLIGHTS
THE NATIONAL HURRICANE CENTER IS MONITORING A TROPICAL DISTURBANCE
THAT IS EXPECTED TO INCREASE THE THREAT FOR HEAVY RAINFALL FOR PARTS
OF FLORIDA AND THE SOUTHEAST IN THE COMING DAYS. THE DAY 4 EXCESSIVE
RAINFALL OUTLOOK COVERING MONDAY MAINTAINS A SLIGHT RISK ACROSS
THIS REGION, WITH A BROADER MARGINAL COVERING MUCH OF THE STATE TO
ACCOUNT FOR THE LINGERING UNCERTAINTY. THE AREA OF HEAVY RAINFALL
IS EXPECTED TO SHIFT UP THE COAST BY TUESDAY, THEREFORE A D5
MARGINAL RISK WAS RAISED FOR PORTIONS OF THE CAROLINA COASTLINE. IT
IS LIKELY THESE AREAS WILL NEED TO BE MODIFIED AS WE GET CLOSER IN
TIME, BUT FOR NOW, THIS SEEMED THE MOST PLAUSIBLE SOLUTION
COVERING THE BETTER MODEL TRACK CONSENSUS. HEAVY RAINFALL ACROSS
FLORIDA MAY LINGER INTO NEXT WEEK WITH FURTHER MODIFICATIONS
DEPENDENT ON TRACK OF THIS SYSTEM.
MODELS SHOW A POTENTIAL MESOSCALE SYSTEM RIDING THE TOP OF THE
RIDGE INTO THE UPPER MIDWEST EARLY NEXT WEEK. A MARGINAL RISK ON
THE DAY 4 ERO STRETCHES FROM THE NORTHERN HIGH PLAINS TO THE LOWER
GREAT LAKES REGION WITH A SMALL SLIGHT RISK ACROSS PARTS OF
SOUTHEAST MINNESOTA AND SOUTHERN WISCONSIN GIVEN AMPLE MOISTURE,
INSTABILITY, AND SOME SOIL SENSITIVITY. SOME RAIN WILL CONTINUE
EAST INTO THE OHIO VALLEY AND NORTHEAST MIDDLE OF NEXT WEEK; A
MARGINAL RISK AREA WAS RAISED FOR DAY 5 FOR THE LOWER GREAT LAKES
TO THE NORTHEAST.
MONSOONAL MOISTURE ON THE WESTERN SIDE OF THE RIDGE SHOULD KEEP A
WET AND UNSETTLED PATTERN IN PLACE FROM THE FOUR CORNERS REGION
NORTHWARD INTO THE ROCKIES/HIGH PLAINS THROUGH MUCH OF THE EXTENDED
PERIOD. MARGINAL RISKS FOR EXCESSIVE RAIN ARE IN EFFECT FOR
PARTS OF THE SOUTHWEST/FOUR CORNERS THROUGH TUESDAY MORNING.
MUCH OF THE WEST COAST SHOULD BE MODESTLY ABOVE NORMAL MUCH OF THE
PERIOD, BUT THE GREATEST THREAT FOR HAZARDOUS HEAT WILL BE ACROSS
PARTS OF SOUTHERN CALIFORNIA AND THE DESERT SOUTHWEST THIS WEEKEND
INTO EARLY NEXT WEEK, WITH DAYTIME HIGHS EXCEEDING 110F LIKELY. FOR
THE CENTRAL U.S. THE ABOVE NORMAL TEMPERATURES ARE EXPECTED TO
SHIFT TOWARD THE SOUTH-CENTRAL AND SOUTHEAST REGIONS. THIS WILL
LIKELY RESULT IN DEVELOPING A MODERATE TO MAJOR HEATRISK ACROSS
THE SOUTH/SOUTHEAST, WITH SOME LOCALIZED EXTREME ACROSS PARTS OF
THE CENTRAL GULF COAST STATES. NORTHERN TIER SHOULD REMAIN NEAR TO
BELOW NORMAL THROUGH THE PERIOD AS WEAK SHORTWAVE ENERGIES MOVE
THROUGH.
CAMPBELL/KONG
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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