965
FXUS21 KWNC 051928
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 05 2024
SYNOPSIS: PERSISTENT, BROAD MID-LEVEL HIGH PRESSURE IS PREDICTED TO EXTEND FROM
THE GREAT LAKES AND MIDWEST TO THE SOUTHWESTERN CONTIGUOUS U.S. (CONUS),
CONTRIBUTING TO INCREASED CHANCES FOR EXCESSIVE HEAT OVER PORTIONS OF THE
EAST-CENTRAL AND SOUTHWESTERN STATES EARLY IN THE FORECAST PERIOD. HEAVY
PRECIPITATION IS FAVORED FOR PORTIONS OF THE GULF COAST AND FLORIDA EARLY IN
WEEK-2, WITH POSSIBLE FLOODING ACROSS MUCH OF THIS SAME AREA. THERE IS
SIGNIFICANT UNCERTAINTY AS TO THE DEVELOPMENT AND FUTURE TRACKS OF POTENTIAL
TROPICAL SYSTEMS DURING THIS FORECAST PERIOD. DESPITE THE UNCERTAINTY, IT WOULD
BE PRUDENT FOR INTERESTS ALONG THE GULF COAST TO KEEP UPDATED WITH THE LATEST
TROPICAL WEATHER CONDITIONS AS WE MOVE PAST THE CLIMATOLOGICAL PEAK OF THE
ATLANTIC HURRICANE SEASON.
HAZARDS
SLIGHT RISK OF EXCESSIVE HEAT FOR THE EASTERN DAKOTAS, UPPER AND MIDDLE
MISSISSIPPI VALLEY AND OHIO VALLEY, FRI-SUN, SEP 13-15.
SLIGHT RISK OF EXCESSIVE HEAT FOR THE DESERT SOUTHWEST, FRI, SEP 13.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE GULF COAST AND FLORIDA,
FRI-SAT, SEP 13-14.
SLIGHT RISK OF HIGH WINDS OVER THE NORTHERN AND CENTRAL PLAINS, FRI, SEP 13.
FLOODING POSSIBLE ALONG MUCH OF THE GULF COAST AND NORTHERN AND CENTRAL
FLORIDA.
RISK FOR RAPID ONSET DROUGHT FOR PORTIONS OF THE OHIO, TENNESSEE, AND MIDDLE
MISSISSIPPI VALLEYS.
DETAILED SUMMARY
FOR SUNDAY SEPTEMBER 08 - THURSDAY SEPTEMBER 12:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY SEPTEMBER 13 - THURSDAY SEPTEMBER 19: AN ANOMALOUS MID-LEVEL RIDGE
IS PREDICTED TO EXTEND FROM HUDSON BAY, CANADA, ACROSS THE GREAT LAKES,
MIDWEST, AND INTO THE SOUTHWEST. MULTIPLE MODELS INDICATE MAXIMUM 500-HPA
HEIGHTS ACROSS THE UNITED STATES RANGING FROM 60-90 METERS ABOVE NORMAL OVER
THE GREAT LAKES AND UPPER MISSISSIPPI VALLEY, WITH HIGHER HEIGHTS NORTH OF THE
CANADIAN BORDER. ANOTHER ANOMALOUS RIDGE IS FORECAST SOUTH OF THE ALEUTIANS,
WITH MAXIMUM HEIGHTS GREATER THAN 120 METERS ABOVE NORMAL. WEAK MID-LEVEL
TROUGHS ARE PREDICTED FOR WESTERN AND CENTRAL ALASKA, WEST COAST OF THE CONUS,
AND THE SOUTHEAST.
A SLIGHT RISK (20-40% CHANCE) OF EXCESSIVE HEAT IS DEPICTED FROM EASTERN
PORTIONS OF THE NORTHERN PLAINS SOUTHEASTWARD ACROSS THE UPPER AND MIDDLE
MISSISSIPPI VALLEY, AND INTO THE OHIO VALLEY, SEP 13-15. THIS IS ASSOCIATED
WITH THE PROXIMITY OF A MODERATELY STRONG ANOMALOUS RIDGE AND POSITIVE HEIGHT
DEPARTURES IN THAT REGION. WITHIN THIS SLIGHT RISK AREA, THE ECENS AND GEFS
MODELS PREDICT 2-METER TEMPERATURES WILL RANGE FROM 10-15 DEGREES F ABOVE
NORMAL, WITH DAYTIME HIGH TEMPERATURES PEAKING NEAR 90 DEGREES F. THESE HIGH
TEMPERATURES COMBINED WITH LOW DEW POINTS AND GUSTY WINDS OF ABOUT 15-20 MPH
MAY INCREASE THE RISK OF WILDFIRES ACROSS THE REGION. ANOTHER SLIGHT RISK AREA
FAVORING EXCESSIVE HEAT IS POSTED ACROSS THE DESERT SOUTHWEST, SEP 13, ALSO
BASED ON MID-LEVEL RIDGING AND POSITIVE HEIGHT DEPARTURES. TWO-METER
TEMPERATURE ANOMALIES ARE PREDICTED BY THE ENSEMBLE MEANS TO RANGE FROM 5-10
DEGREES ABOVE NORMAL, WITH A FEW LOCATIONS HAVING SLIGHTLY LARGER ANOMALIES.
MAXIMUM DAYTIME HIGH TEMPERATURES MAY REACH 105-110 DEGREES F. THEREAFTER, A
SIGNIFICANT MID-LEVEL TROUGH IS PREDICTED TO MOVE INTO THE INTERMOUNTAIN WEST,
WITH ENHANCED WINDS AND POSSIBLE INCREASE IN WILDFIRE RISK.
A SLIGHT RISK OF HEAVY PRECIPITATION HAS BEEN POSTED ALONG MOST OF THE GULF
COAST AND FLORIDA, SEP 13-14, ASSOCIATED WITH A DECAYING MEAN FRONTAL ZONE
FORECASTED TO BE DRAPED ACROSS THIS REGION. PRECIPITATION GUIDANCE FROM THE
PROBABILISTIC EXTREMES TOOLS (PETS) AND FROM THE UNCALIBRATED ECENS PREDICT
THREE-DAY PRECIPITATION AMOUNTS WITHIN THIS VALID PERIOD TO EXCEED THE 85TH
PERCENTILE OF THE HISTORICAL DISTRIBUTION, AND REACH AT LEAST 1 INCH, WITH THE
BULK OF THE PRECIPITATION FORECASTED OFF THE COAST. MOST MODEL GUIDANCE TODAY
INDICATES A RAPID TAPERING OFF OF PRECIPITATION ALONG THE GULF COAST,
ESPECIALLY LATER IN THE PERIOD. A POSSIBLE FLOOD RISK AREA IS HIGHLIGHTED BASED
ON THE NATIONAL WATER CENTER’S (NWC) EXPERIMENTAL FLOOD HAZARD OUTLOOK FOR DAYS
1-7 (WEEK-1), WHICH DEPICTS POSSIBLE FLOODING ALONG/NEAR MOST OF THE GULF
COASTAL AREA, AND NORTHERN FLORIDA. THIS FLOOD RISK IS EXPECTED TO EXTEND INTO
THE EARLY PORTION OF THE WEEK-2 TIME FRAME. OVER THE MAIN DEVELOPMENT REGION
(MDR) OF THE TROPICAL ATLANTIC BASIN, FIVE TROPICAL WAVES ARE CURRENTLY (2PM
EDT TODAY) BEING MONITORED BY THE NATIONAL HURRICANE CENTER (NHC) FOR POSSIBLE
DEVELOPMENT. AT THIS TIME, THERE IS LITTLE CONFIDENCE REGARDING THE FUTURE
TRACK OR INTENSITY OF ANY OF THESE SYSTEMS. THIS IS A VERY UNCERTAIN TIME FOR
THE GULF COAST AREA, INCLUDING FLORIDA, FOR CONFIDENCE IS LOW IN THE
DEVELOPMENT OF ANY ONE TROPICAL SYSTEM. THIS SITUATION WILL CONTINUE TO BE
MONITORED AS WE APPROACH THE CLIMATOLOGICAL PEAK OF THE ATLANTIC HURRICANE
SEASON. IN ADDITION, SEA SURFACE TEMPERATURES ACROSS THE GULF OF MEXICO ARE
MORE THAN ADEQUATE IN INTENSIFYING ANY SYSTEM THAT MAY FORM DURING THIS PERIOD.
DETERMINISTIC MODEL RUNS HAVE INDICATED THE POSSIBILITY OF A TROPICAL CYCLONE
OVER THE EASTERN PACIFIC MOVING PAST THE MOUTH OF THE GULF OF CALIFORNIA DURING
WEEK-2. THESE EVENTS ARE SOMETIMES ACCOMPANIED BY GULF SURGES OF MOISTURE INTO
THE AMERICAN SOUTHWEST, AND THE LIKELIHOOD OF THIS OCCURRING WILL BE MONITORED
WITH FUTURE MODEL RUNS.
THE SLIGHT RISK FOR HIGH WINDS AREA THAT HAS BEEN FORECASTED FOR THE PAST FEW
DAYS IS EXPECTED TO WIND DOWN AS THE AREA SHIFTS A BIT SOUTHWARD OVER THE
NORTHERN AND CENTRAL PLAINS, SEP 13. WIND SPEEDS OF ABOUT 20 MPH ARE FAVORED IN
THIS REGION.
THE POTENTIAL FOR RAPID ONSET DROUGHT (ROD) CONTINUES OVER PARTS OF THE OHIO
AND MIDDLE MISSISSIPPI VALLEYS, AND HAS BEEN EXPANDED TODAY TO INCLUDE MORE OF
KENTUCKY AND PARTS OF THE TENNESSEE VALLEY. SOIL MOISTURE VALUES IN THIS REGION
ARE WITHIN THE LOWEST QUARTILE (AND IN SOME CASES, DECILE) OF THE HISTORICAL
DISTRIBUTION. PRECIPITATION DEFICITS WITHIN THE LAST 90 DAYS HAVE MOUNTED FROM
ONE TO AS MUCH AS SIX INCHES.
IN ALASKA, THE SOUTHERN COAST IS FAVORED TO GET ABOVE NORMAL PRECIPITATION
DURING THE WEEK-2 PERIOD, WITH UP TO 2 INCHES PREDICTED BY THE ENSEMBLE MEANS.
HOWEVER, THIS FALLS SOMEWHAT SHORT OF THE HAZARDOUS PRECIPITATION CRITERION FOR
THIS AREA (NEAR 3 INCHES), AND THEREFORE NO HAZARD IS POSTED.
FORECASTER: ANTHONY ARTUSA
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