753
FXUS21 KWNC 101901
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 10 2024
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS FORECAST TO AMPLIFY ACROSS THE CENTRAL AND
EASTERN CONUS TOWARD THE END OF WEEK-1 INTO WEEK-2 RESULTING IN THE FIRST MAJOR
HEAT EVENT OF THE SEASON ACROSS PORTIONS OF THE OHIO VALLEY INTO THE NORTHEAST.
BY THE MIDDLE OF THE PERIOD, THIS FEATURE IS FORECAST TO BROADEN FURTHER,
INCREASING EXCESSIVE HEAT CHANCES ACROSS PARTS OF THE INTERIOR WEST. ENHANCED
SOUTHERLY FLOW AND AN INFLUX OF TROPICAL MOISTURE FAVOR ELEVATED CHANCES OF
HEAVY PRECIPITATION NEAR THE GULF OF MEXICO COAST, ALTHOUGH THERE IS
UNCERTAINTY REGARDING TIMING AND ORIENTATION OF THE HEAVIEST PRECIPITATION.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE MIDWEST, NORTHEAST, AND
MID-ATLANTIC, TUE-THU, JUN 18-20.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL AND EASTERN CONUS
(NOT INCLUDING THE SOUTHERN MOST STATES), TUE-MON, JUN 18-24.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE INTERIOR WEST, THU-MON,
JUN 20-24.
SLIGHT RISK OF HEAVY PRECIPITATION NEAR THE GULF OF MEXICO COAST, TUE-SAT, JUN
18-22.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHERN PLAINS AND
UPPER MISSISSIPPI VALLEY, JUN 18-20.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE ROCKIES AND HIGH PLAINS,
TUE-THU, JUN 18-20.
DETAILED SUMMARY
FOR THURSDAY JUNE 13 - MONDAY JUNE 17:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY JUNE 18 - MONDAY JUNE 24: AT THE END OF WEEK-1, ANOMALOUS RIDGING
IS FORECAST TO AMPLIFY ACROSS THE CENTRAL AND EASTERN CONUS. THIS FAVORS
INCREASED POTENTIAL FOR EXCESSIVE HEAT CONDITIONS BEGINNING ACROSS THE OHIO
VALLEY ON DAY-7, AND FURTHER EXPANDING INTO PARTS OF THE MID-ATLANTIC AND
NORTHEAST AT THE BEGINNING OF WEEK-2. THE ECMWF AND GEFS PROBABILISTIC EXTREMES
TOOLS (PETS) DEPICT AT LEAST A 40 PERCENT CHANCE MAXIMUM TEMPERATURES EXCEED
THE 85TH CLIMATOLOGICAL PERCENTILE OVER THESE AREAS, WITH SOME AREAS REACHING
90 DEG F (95 DEG F ACROSS THE MID-ATLANTIC), AND THE NATIONAL BLEND OF MODELS
(NBM) INDICATING RECORD HIGH DAILY TEMPERATURES. HEAT INDEX VALUES NEAR OR
EXCEEDING 100 (105) DEG F ARE POSSIBLE ACROSS THE OHIO VALLEY AND NORTHEAST
(MID-ATLANTIC). GIVEN THESE SIGNALS, MODERATE RISKS FOR EXCESSIVE HEAT ARE
POSTED ACROSS THE OHIO VALLEY, AND PARTS OF THE MID-ATLANTIC AND NORTHEAST EAST
OF THE APPALACHIANS, JUN 18-20. A BROADER SLIGHT RISK IS POSTED FROM THE MIDDLE
MISSISSIPPI VALLEY THROUGH THE NORTHEAST FOR ALL OF WEEK-2 GIVEN THE FORECAST
PERSISTENCE OF THE POSITIVE MID-LEVEL HEIGHT ANOMALIES, ALTHOUGH PROBABILITIES
IN THE PETS ARE NOT AS HIGH COMPARED TO EARLIER IN THE PERIOD. DRY SOILS ARE
OBSERVED ACROSS PARTS OF THE OHIO VALLEY AND MID-ATLANTIC AND THESE AREAS MAY
NEED TO BE MONITORED FOR DROUGHT DEVELOPMENT GIVEN THE INCREASING TEMPERATURES
AND DECREASING PRECIPITATION CHANCES. THE RIDGING IS FORECAST TO FURTHER EXPAND
WESTWARD LATER IN WEEK-2 AS UPSTREAM TROUGHING WEAKENS BY THE MIDDLE OF THE
PERIOD. THE GEFS AND ECMWF PETS DEPICT AT LEAST A 20 PERCENT CHANCE OF MAXIMUM
TEMPERATURES EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE ACROSS PARTS OF THE
INTERIOR WEST, WITH COVERAGE CONTINUING TO INCREASE THROUGHOUT THE SECOND HALF
OF WEEK-2. THEREFORE A SLIGHT RISK OF EXCESSIVE HEAT IS HIGHLIGHTED ACROSS
PARTS OF THE GREAT BASIN, ROCKIES, AND SOUTHWEST JUN 20-24.
INCREASED SOUTHERLY FLOW IS PREDICTED ACROSS THE GULF COAST WITH THE GEFS AND
ECMWF ENSEMBLES INDICATING A POTENTIAL INFLUX OF TROPICAL MOISTURE DURING
WEEK-2. INITIALLY, THE STRONGEST MOISTURE SURGE IS PREDICTED ACROSS EASTERN
TEXAS AND THE LOWER MISSISSIPPI VALLEY LATE IN WEEK-1 INTO THE EARLY PORTION OF
WEEK-2. BOTH THE GEFS AND ECMWF PETS DEPICT AT LEAST A 20 PERCENT CHANCE 3-DAY
PRECIPITATION TOTALS EXCEED THE 85TH PERCENTILE AND 1-INCH ACROSS THESE AREAS,
WITH THE ECMWF PET EXPANDING THESE PROBABILITIES FURTHER NORTHWARD. THE GEFS
DEPICTS A PERSISTENT FLOW OF MOISTURE ACROSS FLORIDA THROUGHOUT WEEK-2, WITH
SOME INDICATION OF THIS SCENARIO IN THE ECMWF ENSEMBLE LATER IN THE PERIOD. DUE
TO THE CONSIDERABLE UNCERTAINTY IN THE TIMING AND PLACEMENT OF THE HEAVIEST
PRECIPITATION, ONLY A SLIGHT RISK FOR HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS
THE GULF OF MEXICO COAST, JUN 18-22. HOWEVER, INCREASING MODEL AGREEMENT MAY
NECESSITATE A MODERATE RISK IN FUTURE UPDATES GIVEN THE POTENTIAL FOR
SIGNIFICANT RAINFALL TOTALS (UPWARDS OF SEVERAL INCHES) WHERE THE HEAVIEST
MOISTURE AXIS SETS UP. DUE TO THE INCREASING PRECIPITATION CHANCES, THE RAPID
ONSET DROUGHT RISK OVER SOUTHERN TEXAS HAS BEEN DISCONTINUED.
ANOTHER SLIGHT RISK FOR HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY ALONG THE PERIPHERY OF THE RIDGE AXIS, JUN
18-20. TROUGHING UPSTREAM OVER THE WEST EARLY IN THE PERIOD SUPPORTS INCREASED
THUNDERSTORM ACTIVITY ALONG A FRONTAL BOUNDARY SET-UP OVER THE REGION. ANY
STORMS COULD RESULT IN LOCALIZED HEAVY RAINFALL AND FLASH FLOODING. THIS
TROUGHING ALSO SUPPORTS A SLIGHT RISK OF EPISODIC HIGH WINDS ACROSS PORTIONS OF
THE INTERIOR WEST AND HIGH PLAINS, JUNE 18-20. THE GEFS AND ECMWF PETS INDICATE
AT LEAST A 20 PERCENT CHANCE OF WIND SPEEDS EXCEEDING THE 85TH PERCENTILE AND
20 MPH OVER THE HIGHLIGHTED AREA. ANTICIPATED HOT, DRY, AND WINDY CONDITIONS
MAY INCREASE WILDFIRE RISK ACROSS THESE AREAS. AS THE TROUGH LIFTS OUT AND THE
RIDGE BROADENS, THE WIND RISK IS FORECAST TO SUBSIDE.
FORECASTER: THOMAS COLLOW
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