521
FXUS21 KWNC 031809
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 03 2024
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS FORECAST TO AMPLIFY ACROSS THE WESTERN
CONTIGUOUS U.S. (CONUS) FAVORING INCREASING CHANCES OF EXCESSIVE HEAT
CONDITIONS, PARTICULARLY OVER CALIFORNIA’S CENTRAL VALLEY AND THE DESERT
SOUTHWEST WHERE THE HOTTEST TEMPERATURES ARE FORECAST. HURRICANE BERYL,
CURRENTLY NEAR KINGSTON JAMAICA MAY BRING LINGERING ENHANCED PRECIPITATION TO
PARTS OF TEXAS AND THE LOWER MISSISSIPPI VALLEY AT THE ONSET OF WEEK-2, WITH
THE GREATEST IMPACTS EXPECTED FOR THE END OF WEEK-1. HOWEVER, A SECONDARY
TROPICAL DISTURBANCE MAY DEVELOP IN THE CARIBBEAN AND TRACK TO THE GULF COAST
AT THE BEGINNING OF WEEK-2, WHICH MAY BRING HEAVY RAINFALL TO PORTIONS OF TEXAS
AND LOUISIANA ALTHOUGH UNCERTAINTY REMAINS HIGH. SOUTHERLY MOIST FLOW INTO THE
SOUTHWEST CONTINUES INCREASED CHANCES FOR LOCALIZED HEAVY PRECIPITATION IN THE
REGION. PERIODS OF POTENTIALLY HIGH WINDS ACROSS THE CASCADES, SOUTHWESTERN
OREGON, AND CENTRAL AND NORTHERN CALIFORNIA MAY INCREASE THE RISK FOR WILDFIRES
IN THE AREA.
HAZARDS
HIGH RISK OF EXCESSIVE HEAT FOR THE GREAT BASIN, CALIFORNIA, SOUTHWEST, AND
NORTHERN ROCKIES, THU, JUL 11.
MODERATE RISK OF EXCESSIVE HEAT FOR THE WESTERN THIRD OF THE CONUS AND NORTHERN
AND CENTRAL PLAINS, THU-SAT, JUL 11-13.
SLIGHT RISK OF EXCESSIVE HEAT FOR THE WESTERN THIRD OF THE CONUS AND NORTHERN
AND CENTRAL PLAINS, THU-SUN, JUL 11-14.
SLIGHT RISK OF PERIODIC HEAVY PRECIPITATION FOR PORTIONS OF ARIZONA AND WESTERN
NEW MEXICO, SAT-TUE, JUL 14-17.
SLIGHT RISK FOR PERIODS OF HEAVY PRECIPITATION FOR PORTIONS OF SOUTHEASTERN
TEXAS AND THE LOWER MISSISSIPPI VALLEY, THU-FRI, JUL 11-12.
SLIGHT RISK FOR HIGH WINDS ALONG THE LOUISIANA AND EASTERN TEXAS COAST,
THU-FRI, 11-12.
SLIGHT RISK OF EPISODIC HIGH WINDS ACROSS THE CASCADES, SOUTHWESTERN OREGON,
AND CENTRAL AND NORTHERN CALIFORNIA, THU-SUN, JUL 11-14.
RAPID ONSET DROUGHT RISK FOR PARTS OF GREAT PLAINS, MISSISSIPPI VALLEY,
TENNESSEE AND OHIO VALLEYS, APPALACHIANS, SOUTHEAST AND MID-ATLANTIC.
DETAILED SUMMARY
FOR SATURDAY JULY 06 - WEDNESDAY JULY 10:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY JULY 11 - WEDNESDAY JULY 17: AN AMPLIFIED MID-LEVEL RIDGE IS
FORECAST TO BE CENTERED OVER THE INTERIOR WEST BY THE BEGINNING OF WEEK-2,
EXPANDING EASTWARD AND GRADUALLY WEAKENING OVER TIME. MULTIPLE MODEL ENSEMBLE
MEANS INDICATE GREATER POSITIVE 500 HPA HEIGHT DEPARTURES OVER THE NORTHERN
ROCKIES AND NORTHERN PLAINS AT THE START OF THE PERIOD, COMPARED TO YESTERDAY,
TRANSLATING TO INCREASED CHANCES FOR EXCESSIVE HEAT ACROSS THESE AREAS. THUS
THE RISKS OF EXCESSIVE HEAT ARE EXPANDED NORTHWARD, WHERE THE PROBABILISTIC
EXTREMES TOOLS (PETS) INDICATE AT LEAST A 60% CHANCE OF MAXIMUM TEMPERATURES
EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE. THE HOTTEST TEMPERATURES ARE
ANTICIPATED FOR THE CALIFORNIA CENTRAL VALLEY AND DESERT SOUTHWEST, WHERE
UNCALIBRATED ENSEMBLE MEANS FORECAST TEMPERATURES REACHING 115 DEG F, WITH
AREAS AS FAR NORTH AS THE NORTHERN GREAT BASIN EXCEEDING TRIPLE DIGITS. A HIGH
RISK (AT LEAST A 60% CHANCE) OF EXCESSIVE HEAT IS DESIGNATED FOR THE GREAT
BASIN, CALIFORNIA, SOUTHWEST, AND NORTHERN ROCKIES, JUL 11, WITH MODERATE RISK
(40-60% CHANCE) CONTINUING THROUGH JUL 13 ACROSS A BROADER AREA OF THE WESTERN
THIRD OF THE CONUS INCLUDING PORTIONS OF THE NORTHERN AND CENTRAL PLAINS. A
BROADER AREA OF SLIGHT RISK IS HIGHLIGHTED FOR JUL 11-14 FOR MUCH OF THE WEST
AND PORTIONS OF THE NORTHERN AND CENTRAL PLAINS.
POSSIBLE SURFACE LOW FORMATION WITH ADJACENT SURFACE HIGH PRESSURE OVER THE
NORTHERN PACIFIC MAY SUPPORT TIGHT PRESSURE GRADIENTS ACROSS THE NORTHWEST AND
CALIFORNIA, THUS A SLIGHT RISK OF EPISODIC HIGH WINDS IS MAINTAINED FOR THE
CASCADES AND NORTHERN AND CENTRAL CALIFORNIA, JUL 11-14. THE GEFS (ECENS) PET
SHOWS AT LEAST A 20% (30%) CHANCE OF WIND SPEEDS OVER SOUTHWESTERN OREGON AND
NORTHERN AND CENTRAL CALIFORNIA EXCEEDING THE 85TH PERCENTILE. HOT, DRY, AND
WINDY CONDITIONS MAY LEAD TO ENHANCED RISK OF WILDFIRES ACROSS WEST COAST
STATES, ESPECIALLY LOCATIONS ALREADY UNDER RED FLAG WARNINGS.
THE INITIAL POSITION OF THE RIDGE AXIS NEAR THE DESERT SOUTHWEST, FAVORS A
DIMINISHING MONSOON SIGNAL EARLY IN WEEK-2. HOWEVER, THE RIDGE IS FORECAST TO
WEAKEN AND SHIFT MORE TO THE EAST LATER IN THE PERIOD TOWARD THE FOUR CORNERS,
WHICH IS MORE FAVORABLE FOR SOUTHERLY MOISTURE FLOW INTO PARTS OF THE
SOUTHWEST. THE PETS INDICATE A GROWING SIGNAL FOR HEAVY PRECIPITATION LATER IN
WEEK-2, WITH PROBABILITIES ABOVE 20 PERCENT FOR 3-DAY PRECIPITATION TOTALS
EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE AND 0.5 INCHES DURING THE LATTER
HALF OF THE PERIOD. THEREFORE, A SLIGHT RISK OF PERIODIC HEAVY PRECIPITATION IS
POSTED ACROSS PORTIONS OF ARIZONA AND WESTERN NEW MEXICO, JUL 14-17. LOCALIZED
FLOODING IS POSSIBLE ACROSS THIS AREA, ALTHOUGH THERE IS TOO MUCH UNCERTAINTY
AT THIS TIME TO DESIGNATE A FLOOD RISK.
AS OF 11AM EDT WEDNESDAY, HURRICANE BERYL IS NEAR JAMAICA. PER THE NATIONAL
HURRICANE CENTER (NHC), THERE IS STILL UNCERTAINTY OF WHETHER IT TRACKS TOWARDS
MEXICO OR TEXAS. REGARDLESS, THERE COULD BE LINGERING HEAVY PRECIPITATION AT
THE ONSET OF WEEK-2 DUE TO THE REMNANTS OF BERYL, ALTHOUGH THE MAJORITY OF
IMPACTS ARE ANTICIPATED FOR THE END OF WEEK-1. THERE IS, HOWEVER, A SECONDARY
DISTURBANCE BEING MONITORED BY THE NHC NEAR THE WINDWARD ISLANDS THAT COULD
APPROACH THE GULF COAST BY THE BEGINNING OF WEEK-2 THAT COULD BRING HEAVY
PRECIPITATION TO THE AREA. THERE IS HIGH UNCERTAINTY REGARDING THE EVOLUTION
AND IMPACTS OF THIS FEATURE, RESULTING IN A SLIGHT RISK OF HEAVY PRECIPITATION
FOR PORTIONS OF SOUTHEASTERN TEXAS AND THE LOWER MISSISSIPPI VALLEY, JUL 11-12.
ANTECEDENT AND POTENTIAL HEAVY RAINFALL COULD LEAD TO INCREASED CHANCES FOR
FLOODING IN PARTS OF THESE AREAS, ALTHOUGH THERE IS TOO MUCH UNCERTAINTY TO
DESIGNATE A RELATED FLOOD RISK AT THIS TIME.
MID-LEVEL TROUGHING PREDICTED OVER THE GREAT LAKES AND OHIO VALLEY MAY SUPPORT
A LINGERING STATIONARY FRONT OVER THE EASTERN SEABOARD FROM THE END OF WEEK-1
INTO WEEK-2. THE ECENS PET CONTINUES TO BE MORE FAVORABLE OF HEAVY RAINFALL
ACROSS PARTS OF THE EAST COAST, INDICATING PARTS OF THIS REGION HAVING AT LEAST
A 20% CHANCE OF 3-DAY RAINFALL EXCEEDING THE 85TH PERCENTILE AND ONE INCH JUL
11-13, WITH THE GEFS MAINTAINING HEAVY PRECIPITATION OFFSHORE AND MORE
LOCALIZED. DUE TO HIGH UNCERTAINTY, A RELATED HEAVY PRECIPITATION HAZARD IS NOT
DESIGNATED FOR THIS REGION.
THE 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
(EASTERN CORN BELT), MID-ATLANTIC, SOUTHEAST, SOUTHERN PLAINS, AND SOUTHERN
CENTRAL PLAINS. THE RECENT HEAT WAVES ACROSS THE EASTERN U.S. HAVE EXACERBATED
THE ONGOING DRYNESS ACROSS THESE AREAS, AND HAVE LED TO MODERATE DROUGHT (D1)
FOR MANY AREAS IN THE EAST. 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. PERIODIC, LOCALIZED
HEAVY PRECIPITATION CANNOT BE RULED OUT DUE TO FRONTAL AND/OR DAYTIME
THUNDERSTORM ACTIVITY, BUT THIS IS UNLIKELY TO RESULT IN ANY MEANINGFUL CHANGE
IN THE POTENTIAL FOR CONTINUED DEVELOPMENT OF DROUGHT CONDITIONS. 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: MELISSA OU
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