154
FXUS21 KWNC 141952
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 14 2023
SYNOPSIS: MULTIPLE DYNAMICAL MODEL ENSEMBLE MEANS FAVOR MID-LEVEL HIGH PRESSURE
ACROSS THE WESTERN CONTIGUOUS U.S. (CONUS) AND MUCH OF THE SOUTHERN CONUS
DURING WEEK-2. ACROSS THE EASTERN LOWER 48 STATES, AN APPROACHING AREA OF
MID-LEVEL LOW PRESSURE WILL DISPLACE THE MID-LEVEL HIGH FARTHER TO THE SOUTH
ALONG WITH ANY ACCOMPANYING REGION OF EXCESSIVE HEAT, CONFINING IT PRIMARILY TO
THE GULF COAST AND FLORIDA. DURING THE WEEK-2 FORECAST PERIOD, THERE ARE
INCREASED CHANCES OF EXCESSIVE HEAT OVER THE NORTHERN HIGH PLAINS. FROM EASTERN
TEXAS TO CENTRAL LOUISIANA, ABNORMALLY DRY CONDITIONS COMBINED WITH EXCESSIVE
HEAT INCREASES THE RISK OF RAPID ONSET DROUGHT (ROD).
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT IN THE VICINITY OF THE TEXAS COAST AND
SOUTHWESTERN LOUISIANA, SAT, JUL 22.
MODERATE RISK OF EXCESSIVE HEAT FROM THE CENTRAL VALLEY OF CALIFORNIA AND THE
DESERT SOUTHWEST EASTWARD ACROSS THE REMAINDER OF ARIZONA AND MUCH OF NEW
MEXICO, SAT-FRI, JUL 22-28.
SLIGHT RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE CENTRAL AND EASTERN GULF
COAST REGION (INCLUDING FLORIDA), SAT-MON, JUL 22-24.
SLIGHT RISK OF EXCESSIVE HEAT FOR THE INTERIOR WESTERN CONUS, ROCKIES, NORTHERN
HIGH PLAINS, TEXAS, AND MUCH OF LOUISIANA, SAT-FRI, JUL 22-28.
DETAILED SUMMARY
FOR MONDAY JULY 17 - FRIDAY JULY 21:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY JULY 22 - FRIDAY JULY 28: THE GFS AND ECMWF ENSEMBLE MEANS PREDICT
MEAN MID-LEVEL TROUGHS OVER THE GULF OF ALASKA AND THE EASTERN CONUS DURING
WEEK-2, AND A SUBTROPICAL RIDGE ACROSS THE SOUTHERN CONUS. THE WESTERN PORTION
OF THE SUBTROPICAL RIDGE OVER THE SOUTHWESTERN CONUS IS FORECAST TO AMPLIFY
ACROSS THE WEST, CONFINED ON EITHER SIDE BY MID-LEVEL TROUGHS. THE
AMPLIFICATION OF THIS RIDGE, AND THE PREDICTED DIGGING OF THE MID-LEVEL TROUGH
ACROSS THE EASTERN CONUS INDICATES A GENERAL WESTWARD SHIFT IN WHERE THE AREAS
OF EXCESSIVE HEAT ARE MOST LIKELY TO BE.
TODAY'S HAZARDOUS TEMPERATURE MAP DEPICTS A SLIGHT (20%) CHANCE OF EXCESSIVE
HEAT FOR PORTIONS OF THE CENTRAL AND EASTERN GULF COAST REGION (INCLUDING
FLORIDA), JUL 22-24. THIS IS BASED ON FORECASTS OF DAYTIME HIGH TEMPERATURES IN
THE 90'S, HEAT INDEX VALUES AROUND 105 DEG F, AND OVERNIGHT MINIMUM
TEMPERATURES IN THE UPPER 70'S TO LOW 80'S. A SLIGHT CHANCE OF EXCESSIVE HEAT
IS ALSO POSTED FOR INTERIOR PORTIONS OF THE WESTERN CONUS, THE ROCKIES, THE
NORTHERN HIGH PLAINS, TEXAS, AND MUCH OF LOUISIANA THROUGHOUT THE DURATION OF
THE WEEK-2 PERIOD (JUL 22-28). THIS WIDESPREAD AREA OF PREDICTED EXCESSIVE HEAT
IS RELATED TO THE PROXIMITY OF A MID-LEVEL RIDGE AND POSITIVE 500-HPA HEIGHT
ANOMALIES, AND IS SUPPORTED BY VARIOUS CALIBRATED AND UNCALIBRATED WEEK-2
EXCESSIVE HEAT FORECAST TOOLS, BASED ON GEFS AND ECMWF ENSEMBLE MEAN DRY-BULB
TEMPERATURES AND HEAT INDEX VALUES. THE 6Z GEFS PREDICTED 2-METER AIR
TEMPERATURES RANGE FROM THE 90'S IN THE NORTHERN HIGH PLAINS, NORTHERN
INTERMOUNTAIN REGION AND LOUISIANA, TO 100-110 DEGREES IN TEXAS (ESPECIALLY
EARLY IN WEEK-2) AND THE CENTRAL VALLEY OF CALIFORNIA, TO 110+ DEGREES IN THE
DESERT SOUTHWEST. MONSOONAL CLOUDINESS AND PRECIPITATION IN PARTS OF THE
SOUTHWEST ARE EXPECTED TO KEEP TEMPERATURES ABOUT 5-8 DEGREES COOLER THAN THEY
ARE NOW, THOUGH THIS DOESN'T WARRANT REMOVING THE EXCESSIVE HEAT RISK FOR THE
REGION.
MODERATE CHANCES (40%) OF EXCESSIVE HEAT ARE INDICATED FOR THE VICINITY OF THE
TEXAS COAST AND SOUTHWESTERN LOUISIANA ON JUL 22, BEFORE THE HEAT HAZARD TIMES
OFF. THE MODERATE RISK AREA INDICATED OVER THE REMAINDER OF TEXAS YESTERDAY IS
NOT AS WELL SUPPORTED TODAY, SO IT WAS REMOVED. WITH THE EXPECTED WESTWARD
SHIFT OF THE BRUNT OF THE EXCESSIVE HEAT DURING WEEK-2, A MORE DURABLE MODERATE
RISK AREA IS NOW INDICATED OVER CALIFORNIA'S CENTRAL VALLEY, THE DESERT
SOUTHWEST, AND CONTINUING EASTWARD THROUGH MUCH OF NEW MEXICO.
THE ELEVATED RISK OF RAPID ONSET DROUGHT DEVELOPMENT IS CONTINUED FOR PARTS OF
EAST TEXAS AND LOUISIANA, DUE TO RECENT (IN SOME CASES RECORD) HEAT IN RECENT
WEEKS AND EXPECTED EXCESSIVE HEAT FORECAST TO PERSIST INTO THE WEEK-2 PERIOD.
AS SUCH, A RISK OF RAPID ONSET DROUGHT (ROD) IS MAINTAINED FROM MUCH OF EASTERN
TEXAS TO CENTRAL LOUISIANA.
NO HAZARDS ARE POSTED FOR ALASKA DURING WEEK-2. ABOVE NORMAL TEMPERATURES ARE
FAVORED FOR MOST OF THE MAINLAND, WHILE BELOW NORMAL TEMPERATURES ARE INDICATED
FOR SOUTHEAST ALASKA. FOR MUCH OF CENTRAL AND EASTERN PORTIONS OF ALASKA ABOVE
NORMAL PRECIPITATION IS FAVORED, WITH NEAR NORMAL PRECIPITATION FAVORED
ELSEWHERE.
FORECASTER: ANTHONY ARTUSA
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