653
FXUS21 KWNC 041832
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 04 2023
SYNOPSIS: MID-LEVEL HIGH PRESSURE PERSISTS OVER THE SOUTHERN CONTIGUOUS U.S.
(CONUS) DURING WEEK-2, LEADING TO THE POTENTIAL FOR EXCESSIVE HEAT FOR THE
DESERT SOUTHWEST AND SOUTHERN PLAINS. MID-LEVEL LOW PRESSURE OVER THE GREAT
LAKES COMBINED WITH ABUNDANT TROPICAL MOISTURE INCREASES THE RISK FOR HEAVY
PRECIPITATION FOR PORTIONS OF THE NORTHEASTERN CONUS. SNOWMELT SEASON CONTINUES
FOR PORTIONS OF THE WEST AFTER EXCEPTIONAL WINTER ACCUMULATIONS, LEADING TO THE
CONTINUED POTENTIAL FOR FLOODING, WHILE ABNORMALLY DRY CONDITIONS OVER PORTIONS
OF TEXAS AND LOUISIANA RESULT IN THE POTENTIAL FOR RAPID ONSET DROUGHT (ROD).
HAZARDS
MODERATE RISK FOR EXCESSIVE HEAT FOR PORTIONS OF THE DESERT SOUTHWEST, SOUTHERN
ROCKIES, AND SOUTHERN PLAINS, WED-MON, JUL 12-17.
SLIGHT RISK FOR EXCESSIVE HEAT FOR MUCH OF THE SOUTHERN CONUS, WED-TUE, JUL
12-18.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE OHIO AND MIDDLE
MISSISSIPPI VALLEYS, WED-SUN, JUL 12-16.
SLIGHT RISK FOR HIGH WINDS FOR PORTIONS OF THE SOUTHERN AND CENTRAL PLAINS,
WED-TUE, JUL 12-18.
POSSIBLE FLOODING FOR PORTIONS OF CALIFORNIA AND NEVADA.
RAPID ONSET DROUGHT RISK ACROSS PORTIONS OF EASTERN TEXAS AND CENTRAL LOUISIANA.
DETAILED SUMMARY
FOR FRIDAY JULY 07 - TUESDAY JULY 11:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JULY 12 - TUESDAY JULY 18: ENSEMBLE MODEL SOLUTIONS FROM THE
GEFS, ECMWF, AND CMCE ALL DEPICT POSITIVE 500-HPA HEIGHT ANOMALIES CENTERED
OVER THE DESERT SOUTHWEST IN EXCESS OF 595 DM PERSISTING THROUGHOUT THE
FORECAST PERIOD. THIS FAVORS INCREASING TEMPERATURES ACROSS THE SOUTHERN CONUS,
LEADING TO THE INCREASED POTENTIAL FOR EXCESSIVE HEAT. THE PROBABILISTIC
EXTREMES TOOL (PET) OF ALL THREE ENSEMBLES AFOREMENTIONED INDICATE AT LEAST A
40% PROBABILITY OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE AND AT
LEAST 100 DEG F FOR MUCH OF THE SOUTHERN PLAINS AND THE DESERT SOUTHWEST FOR
JUL 12-17, THEREFORE A MODERATE RISK FOR EXCESSIVE HEAT IS POSTED FOR MUCH OF
THE DESERT SOUTHWEST, SOUTHERN ROCKIES AND THE SOUTHERN PLAINS FOR THIS TIME
PERIOD. ADDITIONALLY, THE PETS INDICATE AT LEAST A 20% PROBABILITY OF EXCEEDING
THE 85TH PERCENTILE FOR MUCH OF THE SOUTHERN CONUS FOR THE WHOLE WEEK-2 PERIOD,
THUS A SLIGHT RISK FOR EXCESSIVE HEAT IS POSTED FOR THE REGION.
AT THE BEGINNING OF WEEK-2 MULTIPLE MODEL SOLUTIONS CONTINUE TO DEPICT
TROUGHING OVER THE GREAT LAKES, LEADING TO ENHANCED PRECIPITATION FOR THE
NORTHEASTERN CONUS. THE CMCE AND ECMWF PETS BOTH INDICATE AT LEAST A 20%
PROBABILITY OF 3-DAY PRECIPITATION ACCUMULATIONS EXCEEDING THE 85TH PERCENTILE
AND AT LEAST AN INCH FOR PORTIONS OF THE OHIO AND MIDDLE MISSISSIPPI VALLEYS,
JUL 12-16, SUPPORTING A SLIGHT RISK FOR HEAVY PRECIPITATION FOR THE REGION.
WITH BROAD TROUGHING ANTICIPATED OVER THE GREAT LAKES AS WELL AS A SIGNIFICANT
CONTINENTAL-SCALE NORTH-SOUTH TEMPERATURE GRADIENT OVER THE CENTRAL CONUS
DURING WEEK-2, PERIODS OF HIGH WINDS ARE FAVORED FOR PORTIONS OF THE SOUTHERN
AND CENTRAL PLAINS. PETS INDICATE AT LEAST A 20% PROBABILITY OF WIND SPEEDS
EXCEEDING THE 85TH PERCENTILE THROUGHOUT THE FORECAST PERIOD, THUS A SLIGHT
RISK FOR HIGH WINDS IS POSTED FOR PORTIONS OF THE SOUTHERN AND CENTRAL PLAINS
FOR JUL 12-18.
DROUGHT CONCERNS ARE FORECAST TO INCREASE ACROSS PARTS OF EAST TEXAS AND
CENTRAL LOUISIANA AS THE HEAT OF SUMMER BUILDS AND A PERSISTENCE OF
BELOW-NORMAL PRECIPITATION IS FORECAST FOR THE REGION. WHILE SOME PRECIPITATION
IS PREDICTED FOR CENTRAL LOUISIANA IN THE COMING WEEK, ACCUMULATIONS ARE NOT
EXPECTED TO MAKE A SIGNIFICANT DIFFERENCE FROM A SOIL MOISTURE PERSPECTIVE SO
NO CHANGES ARE MADE TO THE ROD OUTLOOK.
SNOWMELT SEASON CONTINUES ACROSS THE WESTERN CONUS AFTER ACCUMULATING A VERY
LARGE AND IN SOME CASES RECORD-BREAKING SNOWPACK, INDUCING RIVER FLOODING
ESPECIALLY ACROSS HIGHER ELEVATIONS FOR SOME AREAS IN THE WEST. AS SNOWMELT
CONTINUES IN PARTS OF THE SIERRA NEVADA, FLOODING MAY CONTINUE TO OCCUR ALONG
SOME RIVERS, AND IN AREAS ADJACENT TO THE HIGHER ELEVATIONS.
FORECASTER: DANNY BARANDIARAN
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