831
FXUS21 KWNC 161811
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 16 2024
SYNOPSIS: MID-LEVEL HIGH PRESSURE CONTINUES TO BE PREDICTED TO BE CENTERED OVER
THE FOUR CORNERS REGION DURING WEEK-2, BRINGING INCREASED CHANCES OF EXCESSIVE
HEAT TO PORTIONS OF THE SOUTHERN PLAINS, NEW MEXICO, LOWER MISSISSIPPI VALLEY,
AND SONORAN DESERT. MULTIPLE MODELS INDICATE GREATER POSITIVE MID-LEVEL HEIGHT
DEPARTURES OVER THE NORTH-CENTRAL CONTIGUOUS U.S. (CONUS) RESULTING IN A SLIGHT
RISK OF EXCESSIVE HEAT FOR THE NORTHERN AND CENTRAL PLAINS AT THE BEGINNING OF
THE PERIOD. THERE IS POTENTIAL FOR A SURFACE LOW IN THE GULF OF ALASKA TO
BRING ENHANCED PRECIPITATION TO PARTS OF SOUTHEASTERN MAINLAND ALASKA DURING
THE LATTER PART OF THE PERIOD. OVER THE EASTERN AND CENTRAL PACIFIC THERE IS AN
INCREASED POTENTIAL FOR TROPICAL CYCLONE FORMATION WHICH COULD LEAD TO ENHANCED
PRECIPITATION AND LARGE SWELLS FOR PARTS OF THE HAWAIIAN ISLANDS.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE SOUTHERN PLAINS, NEW
MEXICO, AND SOUTHEASTERN ARIZONA, SAT-SUN, AUG 24-25.
SLIGHT RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE SOUTHERN PLAINS, NEW MEXICO,
LOWER MISSISSIPPI VALLEY, AND SONORAN DESERT, SAT-FRI, AUG 24-30.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PARTS OF THE NORTHERN AND CENTRAL PLAINS,
SAT-MON, AUG 24-26.
RAPID ONSET DROUGHT RISK FOR PORTIONS OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY.
DETAILED SUMMARY
FOR MONDAY AUGUST 19 - FRIDAY AUGUST 23:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY AUGUST 24 - FRIDAY AUGUST 30: TODAY’S 0Z ECENS ENSEMBLE MEAN SHOWS
SLIGHTLY GREATER POSITIVE HEIGHT DEPARTURES OVER THE FOUR CORNERS COMPARED TO
YESTERDAY, ALTHOUGH THE GEFS INDICATES SLIGHTLY WEAKER DEPARTURES. DESPITE SOME
DIFFERENCES REGARDING HIGHER PROBABILITIES FOR EXCESSIVE HEAT IN THE ECENS
TEMPERATURE AND HEAT TOOLS COMPARED TO THE GEFS, THE SLIGHT RISK AREA (20-40%
CHANCE) FOR THIS HAZARD REMAINS SIMILAR TO YESTERDAY, FOR PORTIONS OF THE
SOUTHERN PLAINS, NEW MEXICO, LOWER MISSISSIPPI VALLEY, AND SONORAN DESERT
THROUGHOUT WEEK-2. THE GEFS ENSEMBLE MEAN INDICATES THE CENTER OF THE MID-LEVEL
HIGH PRESSURE SHIFTED FURTHER WEST COMPARED TO YESTERDAY, FOCUSED MORE OVER THE
FOUR CORNERS AND LESS OVER TEXAS. THIS TRANSLATES TO A DECREASE IN SPATIAL
COVERAGE FOR THE MODERATE RISK OF EXCESSIVE HEAT OVER TEXAS BUT INCLUSION OF
SOUTHEASTERN ARIZONA, WHERE THE PROBABILISTIC EXTREMES TOOLS (PETS) SHOW 40-60%
CHANCES OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE CLIMATOLOGICALLY,
WITH HEAT INDEX VALUES ANTICIPATED TO NEAR OR EXCEED TRIPLE DIGITS (DEG F).
THERE IS NOTICEABLY DECREASED SPATIAL COVERAGE IN THE NATIONAL BLEND OF MODELS
(NBM) INDICATING POTENTIALLY NEAR RECORD BREAKING TEMPERATURES ACROSS TEXAS AND
NEW MEXICO AUG 24, POTENTIALLY HINTING AT GRADUALLY DECREASING HEAT SIGNALS.
MULTIPLE MODEL ENSEMBLE MEANS SHOW MORE ANOMALOUS 500 HPA HEIGHT DEPARTURES
ACROSS THE CENTRAL AND NORTHERN PLAINS, TRANSLATING TO THE PETS INDICATING
GREATER PROBABILITIES FOR REACHING HAZARDOUS CRITERIA. THEREFORE, A SLIGHT RISK
OF EXCESSIVE HEAT IS HIGHLIGHTED FOR PARTS OF THE NORTHERN AND CENTRAL PLAINS,
AUG 24-26, WHERE PETS INDICATE MAXIMUM TEMPERATURES EXCEEDING THE 85TH
PERCENTILE AND 95 DEG F (100 DEG F ACROSS THE CENTRAL PLAINS).
A STATIONARY FRONT COULD LINGER ACROSS PARTS OF THE EAST COAST FROM THE END OF
WEEK-1 INTO WEEK-2 WHICH COULD SUPPORT ENHANCED PRECIPITATION ACROSS THE
COASTAL CAROLINAS AND FLORIDA. THERE IS NO DESIGNATED RISK FOR HEAVY
PRECIPITATION AT THE TIME FOR THIS AREA DUE TO MODEL UNCERTAINTY REGARDING
ACCUMULATING TOTALS, AND WITH THE HEAVIEST PRECIPITATION SIGNALS BEING MORE
OFFSHORE.
AS OF 11AM PDT, THE NATIONAL HURRICANE CENTER (NHC) INDICATES AN AREA OF LOW
PRESSURE OFFSHORE OF SOUTHWESTERN MEXICO WITH A 80% CHANCE OF FORMING INTO A
TROPICAL CYCLONE IN THE NEXT 7 DAYS. ADDITIONALLY, THE CLIMATE PREDICTION
CENTER (CPC) GLOBAL TROPICS HAZARDS OUTLOOK INDICATES AT LEAST A 20% CHANCE OF
TROPICAL CYCLONE (TC) FORMATION SOUTHWEST OF MEXICO THAT IS VALID THROUGH THE
MIDDLE OF WEEK-2. ANY POSSIBLE TCS COULD INCREASE THE POTENTIAL FOR ENHANCED
MONSOONAL MOISTURE INTO THE SOUTHWEST, WHICH COULD RESULT IN LOCALIZED HEAVY
PRECIPITATION ACROSS THE FOUR CORNERS.THERE IS TOO MUCH MODEL UNCERTAINTY TO
POST AN ASSOCIATED HAZARD AT THIS TIME.
AS OF 2AM HST, THE CENTRAL PACIFIC HURRICANE CENTER IS MONITORING TWO
DISTURBANCES IN THE CENTRAL PACIFIC, WITH ONE SOUTHEAST OF HAWAII FORECAST WITH
A 50% CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE DURING THE NEXT WEEK, AND
THE OTHER LOCATED FURTHER WEST WITH 40% CHANCES OF FORMATION FOR THE SAME
PERIOD. SHOULD EITHER OF THESE FORM, IT MAY LEAD TO ENHANCED PRECIPITATION,
WINDY CONDITIONS, AND LARGE SWELLS FOR PARTS OF THE HAWAIIAN ISLANDS DURING
WEEK-2. GUSTY CONDITIONS COULD ALSO LEAD TO INCREASED RISK OF WILDFIRES, GIVEN
THE CURRENT DRY CONDITIONS.
BELOW-NORMAL RAINFALL ANTICIPATED OVER MUCH OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY DURING WEEK-2, COMBINED WITH INCREASED LIKELIHOOD OF
EXCESSIVE HEAT AND BELOW-NORMAL 30-DAY ACCUMULATED PRECIPITATION, RESULTS IN AN
ELEVATED RISK OF RAPID ONSET DROUGHT (ROD) ACROSS PORTIONS OF THE SOUTHERN
PLAINS AND LOWER MISSISSIPPI VALLEY SUPPORTED BY DECLINING SOIL MOISTURE VALUES
AND DRY CONDITIONS FAVORED OVER THE NEXT TWO WEEKS. WITH RECENT AND ANTICIPATED
HOT AND DRY CONDITIONS INCREASING ACROSS PARTS OF TEXAS, THE ROD RISK AREA HAS
BEEN SLIGHTLY EXPANDED SOUTHWARD.
MID-LEVEL TROUGHING OVER ALASKA MAY SUPPORT A SERIES OF SURFACE LOWS FORMING IN
THE GULF OF ALASKA. THE GREATEST CHANCES FOR ENHANCED PRECIPITATION WOULD BE
FOR SOUTHEASTERN ALASKA DURING THE MIDDLE OF THE PERIOD. THE PETS INDICATE AT
LEAST A 20% CHANCE OF 3-DAY PRECIPITATION EXCEEDING THE 85TH PERCENTILE AND 2
INCHES. AT THIS TIME NO RELATED HAZARDS ARE HIGHLIGHTED.
FORECASTER: MELISSA OU
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