929
FXUS21 KWNC 241922
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 24 2024
SYNOPSIS: MID-LEVEL HIGH PRESSURE ACROSS THE EASTERN CONTIGUOUS U.S. (CONUS) IS
FORECAST FOR MUCH OF THE WEEK-2 PERIOD, CONTINUING INCREASED CHANCES FOR
EXCESSIVE HEAT DURING WEEK-1 INTO WEEK-2 INCLUDING THE FOURTH OF JULY. THIS
MID-LEVEL HIGH IS ANTICIPATED TO SUPPRESS PRECIPITATION AND BRING ABOVE-NORMAL
TEMPERATURES, INCREASING CHANCES FOR RAPID ONSET DROUGHT ACROSS MANY PARTS OF
THE SOUTH-CENTRAL AND EASTERN CONUS. WEAK MID-LEVEL LOW PRESSURE FORECAST
ACROSS THE NORTH-CENTRAL CONUS IS EXPECTED TO HELP LIMIT THE NORTHWARD EXTENT
OF ANY HAZARDOUS HEAT BUT WILL ENHANCE CHANCES FOR HEAVY PRECIPITATION FOR THE
UPPER MISSISSIPPI VALLEY AND GREAT LAKES REGION THROUGHOUT THE PERIOD.
MEANWHILE, A STRONG SURGE OF MOISTURE IS FORECAST TO BUILD INTO THE SOUTHWEST,
LEADING TO CHANCES OF LOCALLY HEAVY RAINFALL AND FLOODING.
HAZARDS
MODERATE RISK FOR EXCESSIVE HEAT FOR PORTIONS OF THE MIDDLE MISSISSIPPI, OHIO
AND TENNESSEE VALLEYS, CENTRAL AND SOUTHERN PLAINS, TUE-WED, JUL 2-3.
MODERATE RISK FOR EXCESSIVE HEAT FOR PORTIONS OF THE MID-ATLANTIC, WED-THU, JUL
3-4.
SLIGHT RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE EASTERN AND CENTRAL U.S.,
TUE-MON, JUL 2-8.
SLIGHT RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE CALIFORNIA CENTRAL VALLEY,
TUE-WED, JUL 2-3.
MODERATE RISK OF HEAVY PRECIPITATION FOR PARTS OF THE SOUTHWEST AND SOUTHERN
ROCKIES, TUE-THU, JUL 2-4.
SLIGHT RISK OF PERIODS OF HEAVY PRECIPITATION FOR PARTS OF THE SOUTHWEST AND
SOUTHERN ROCKIES, TUE-MON, JUL 2-8.
SLIGHT RISK OF PERIODS OF HEAVY PRECIPITATION FOR PORTIONS OF THE NORTHERN
PLAINS, UPPER MISSISSIPPI VALLEY, AND GREAT LAKES, TUE-MON, JUL 2-8.
POSSIBLE FLOODING FOR PORTIONS OF THE NORTHERN PLAINS, UPPER MISSISSIPPI VALLEY.
POSSIBLE FLOODING FOR PORTIONS OF SOUTHERN ARIZONA AND NEW MEXICO.
RAPID ONSET DROUGHT RISK EXTENDING FROM NEW JERSEY AND PENNSYLVANIA SOUTHWARD
THROUGH WESTERN ALABAMA AND NORTHERN FLORIDA.
RAPID ONSET DROUGHT RISK ACROSS THE EASTERN CORN BELT.
RAPID ONSET DROUGHT RISK ACROSS PORTIONS OF EASTERN OKLAHOMA, NORTHEASTERN
TEXAS, AND THE SURROUNDING AREAS.
DETAILED SUMMARY
FOR THURSDAY JUNE 27 - MONDAY JULY 01:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY JULY 02 - MONDAY JULY 08: EXCESSIVE HEAT IS POSSIBLE ACROSS THE
EASTERN CONUS THROUGHOUT MUCH OF THE WEEK-2 PERIOD. THE 0Z GEFS, ECENS, AND
CMCE ENSEMBLE MEANS INDICATE A BROAD AREA OF RIDGING ACROSS MUCH OF THE CENTRAL
AND EASTERN CONUS EARLY IN WEEK-2, BEFORE WEAKENING AND RETROGRADING WESTWARD
BY THE END OF THE PERIOD. THERE IS A POSSIBILITY THAT MODEL INDICATION OF RIDGE
WEAKENING MAY JUST BE THE RESULT OF NORMAL MODEL SPREAD INCREASING DURING THE
PERIOD. THE ECENS AND GEFS PROBABILISTIC EXTREMES TOOLS (PETS) DEPICT SOME
PARTS OF THE CENTRAL AND SOUTHERN PLAINS, MIDDLE MISSISSIPPI, OHIO AND
TENNESSEE VALLEYS AND MID-ATLANTIC HAVING AT LEAST A 40 PERCENT CHANCE OF
MAXIMUM TEMPERATURES EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE EARLY IN THE
WEEK-2 PERIOD. TEMPERATURES IN THE UNCALIBRATED GUIDANCE ARE NEAR OR ABOVE 95
DEG F ACROSS THE OHIO AND MIDDLE MISSISSIPPI VALLEYS, AND 100+ DEG F ACROSS THE
CENTRAL AND SOUTHERN PLAINS ON DAYS 8 AND 9. MEANWHILE IN THE MID-ATLANTIC,
UNCALIBRATED TEMPERATURES ARE COOLER ON DAY 8 BEFORE WARMING INTO THE
UPPER-90’S FOR JUL 3-4. DEWPOINTS ARE FORECAST TO BE RELATIVELY LOWER ON DAY-8
(JUL 2) IN THE WAKE OF A PASSING COLD FRONT, WITH INCREASING MOISTURE
THEREAFTER FAVORING HEAT INDICES NEAR OR ABOVE 100 DEG F ACROSS THE OHIO VALLEY
AND 105 DEG F ACROSS THE MID-ATLANTIC, WITH THE CALIBRATED GEFS/ECENS
SKILL-WEIGHTED HEAT TOOL DEPICTING AT LEAST A 40 PERCENT CHANCE OF HEAT INDICES
EXCEEDING THE 90TH CLIMATOLOGICAL PERCENTILE ACROSS THESE REGIONS. GIVEN THESE
SIGNALS, MODERATE RISKS FOR EXCESSIVE HEAT ARE POSTED ACROSS PORTIONS OF THE
CENTRAL AND SOUTHERN PLAINS, AND THE MIDDLE MISSISSIPPI, OHIO, TENNESSEE
VALLEYS FOR JUL 2-3. WHILE A MODERATE RISK IS POSTED FOR THE MID-ATLANTIC JUL
3-4. A SLIGHT RISK (20-40% CHANCE) FOR EXCESSIVE HEAT IS POSTED ACROSS PORTIONS
OF THE EASTERN AND CENTRAL CONUS FOR ALL OF WEEK-2 BENEATH STRONG MID-LEVEL
HIGH PRESSURE.
EARLY IN THE PERIOD, AN AREA OF MID-LEVEL HIGH PRESSURE ALONG THE CALIFORNIA
COAST MAY PROMOTE EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL VALLEY OF
CALIFORNIA. THE GEFS AND ECENS PETS SUPPORT A 30 TO 40% CHANCE OF TEMPERATURES
EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE AND 100 DEG F ACROSS THE VALLEY.
THEREFORE, A SLIGHT RISK OF EXCESSIVE HEAT IS POSTED FOR THE CENTRAL VALLEY FOR
JUL 2-3. PREDICTED INCREASING ATMOSPHERIC MOISTURE MAY HELP LIMIT TEMPERATURES
ACROSS PARTS OF THE SOUTHWEST AND FOUR CORNERS.
THE 0Z GEFS AND ECMWF ENSEMBLES DEPICT MULTIPLE SHORTWAVE 500-HPA TROUGHS
PROGRESSING EAST FROM THE WESTERN TO THE NORTH-CENTRAL CONUS OVERTOP THE
EXPANDING MID-LEVEL RIDGE. THIS LONGWAVE PATTERN ALONG WITH UNCALIBRATED
24-HOUR PRECIPITATION AMOUNTS FROM THE GEFS AND ECENS SUPPORT A SLIGHT RISK OF
PERIODS OF HEAVY PRECIPITATION ACROSS THE NORTHERN PLAINS, UPPER MISSISSIPPI
VALLEY, AND GREAT LAKES REGION THROUGHOUT WEEK-2. ADDITIONALLY, THUNDERSTORMS
COULD TRIGGER FLASH FLOODING. POSSIBLE HEAVY PRECIPITATION MAY CONTINUE THE
ENHANCED RISK FOR FLOODING ACROSS THE UPPER-MISSISSIPPI VALLEY ESPECIALLY
ACROSS AREAS ALREADY EXPERIENCING FLOODING, ESPECIALLY ACROSS SOUTHERN
MINNESOTA. .
SEVERAL STRONG SURGES OF MOISTURE FORECAST ACROSS THE SOUTHWEST MAY SUPPORT
INCREASED CHANCES FOR HEAVY PRECIPITATION AND FLOODING ACROSS PARTS OF ARIZONA
AND NEW MEXICO. DEWPOINTS IN THE 60’S ARE FORECAST ACROSS MUCH OF THE REGION
THROUGH MUCH OF THE WEEK-2 PERIOD. BOTH THE ECENS AND GEFS PETS DEPICT AT LEAST
A 20% CHANCE OF 3-DAY RAINFALL TOTALS EXCEEDING A HALF-INCH AND THE 85TH
PERCENTILE ACROSS PARTS OF THE SOUTHWEST AND SOUTHERN ROCKIES. MEANWHILE, THESE
TOOLS INDICATE GREATER THAN 40% CHANCES OF 3-DAY PRECIPITATION EXCEEDING THE
85TH PERCENTILE ACROSS SOUTHERN PORTIONS OF ARIZONA. THIS IS ALSO SUPPORTED BY
THE UNCALIBRATED TOOLS WHICH DEPICT EXPANDING COVERAGE OF A HALF-INCH TO ONE
INCH OF PRECIPITATION ACROSS PARTS OF THE REGION. THEREFORE, A MODERATE RISK OF
HEAVY PRECIPITATION IS POSTED FOR PARTS OF SOUTHERN ARIZONA, FOR JUL 2-4. A
BROADER AREA OF SLIGHT RISK OF PERIODIC HEAVY PRECIPITATION IS HIGHLIGHTED FOR
MUCH OF ARIZONA AND NEW MEXICO DURING THE ENTIRE WEEK-2 PERIOD. POSSIBLE FLOOD
RISK IS FORECAST FOR SOUTHERN PARTS OF ARIZONA AND NEW MEXICO WHERE THE
STRONGER PRECIPITATION SIGNALS ARE DEPICTED. PRECIPITATION IS EXPECTED TO BE
ISOLATED AND NOT ALL LOCATIONS WILL EXPERIENCE HEAVY RAINFALL. HOWEVER, FLASH
FLOODING IS POSSIBLE BOTH WHERE PRECIPITATION OCCURS AND IN DOWNSTREAM VALLEYS,
PARTICULARLY IN AND AROUND BURN SCARS WHERE DEBRIS FLOWS CAN BE TRIGGERED BY
HEAVY RAINFALL.
PERSISTENT WARMER AND DRIER THAN NORMAL CONDITIONS OVER AT LEAST THE PAST MONTH
HAVE LED TO A RISK FOR RAPID ONSET DROUGHT FOR PARTS OF THE OHIO VALLEY,
MID-ATLANTIC, SOUTHEAST, AND CENTRAL AND SOUTHERN PLAINS. THE RECENT HEAT WAVES
ACROSS THE EASTERN U.S. HAVE EXACERBATED THE ONGOING DRYNESS ACROSS MANY OF
THESE AREAS. MUCH OF THE AREAS HIGHLIGHTED FOR RISK OF RAPID ONSET DROUGHT HAVE
SEEN LARGE PRECIPITATION DEFICITS OVER THE PAST TWO WEEKS TO A MONTH AND HAVE
SEEN LARGE REDUCTIONS IN AVAILABLE SOIL MOISTURE. THERE IS ADDITIONAL RISK FOR
HIGH EVAPOTRANSPIRATION RATES WITH ABOVE-NORMAL TEMPERATURES FORECAST ACROSS
MUCH OF THE EASTERN CONUS. ALTHOUGH PERIODIC, LOCALIZED HEAVY PRECIPITATION
CANNOT BE RULED OUT DUE TO FRONTAL AND/OR DAYTIME THUNDERSTORM ACTIVITY. HOT
AND DRY WEATHER IS LIKELY TO CONTINUE INTO EARLY JULY, WITH A MODERATE RISK
(40-60% CHANCE) OF EXCESSIVE HEAT FOR PORTIONS OF THE EASTERN CONUS LEADING UP
TO AND INCLUDING THE 4TH OF JULY HOLIDAY. DRY SOILS, STRESSED VEGETATION, AND
REDUCED WATER AVAILABILITY DUE TO LOW PONDS AND STREAMS MAY LEAD TO INCREASED
IMPACTS TO AGRICULTURE AND LIVESTOCK, WITH SEVERAL LOCATIONS ALREADY
EXPERIENCING IMPACTS.
FORECASTER: RYAN BOLT
CLICK HERE TO GO TO PREVIOUS BULLETINS.
The Nexlab HPC Page Main Text Page