452
FXUS21 KWNC 151909
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 15 2024
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS 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. 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 AND NEW
MEXICO, FRI-MON, AUG 23-26.
SLIGHT RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE SOUTHERN PLAINS, NEW MEXICO,
LOWER MISSISSIPPI VALLEY, AND SONORAN DESERT, FRI-THU, AUG 23-29.
RAPID ONSET DROUGHT RISK FOR PORTIONS OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY.
DETAILED SUMMARY
FOR SUNDAY AUGUST 18 - THURSDAY AUGUST 22:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY AUGUST 23 - THURSDAY AUGUST 29: THERE CONTINUES TO BE MULTI-MODEL
DEPICTIONS OF AMPLIFIED MID-LEVEL HIGH PRESSURE CENTERED OVER THE FOUR CORNERS
DURING WEEK-2. THE MODERATE RISK OF EXCESSIVE HEAT IS CONTINUED FOR PORTIONS OF
THE SOUTHERN PLAINS AND NEW MEXICO, AUG 23-26, WHERE THE PROBABILISTIC EXTREMES
TOOLS (PETS) SHOW 40-60% CHANCES OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH
PERCENTILE CLIMATOLOGICALLY, WITH HEAT INDEX VALUES ANTICIPATED TO EXCEED
TRIPLE DIGITS (DEG F). GREATER THAN 60% CHANCES ARE INDICATED IN THE PETS ON
DAY 8 (AUG 23) OVER NEW MEXICO AND TEXAS. THE MODERATE RISK AREA HAS BEEN
SLIGHTLY EXPANDED INTO CENTRAL NEW MEXICO GIVEN INCREASING CHANCES FOR REACHING
HAZARDOUS HEAT CRITERIA IN MULTIPLE TOOLS. THE NATIONAL BLEND OF MODELS (NBM)
INDICATES THE POTENTIAL FOR NEAR RECORD BREAKING TEMPERATURES ACROSS TEXAS AND
NEW MEXICO DURING THE HIGHLIGHTED MODERATE RISK PERIOD, ESPECIALLY AUG 23-24.
SOME LOCATIONS ACROSS SOUTHERN TEXAS MAY REACH 105 DEG F. A BROADER SLIGHT RISK
AREA IS HIGHLIGHTED ACROSS THE SOUTHERN PLAINS, NEW MEXICO, LOWER MISSISSIPPI
VALLEY, AND SONORAN DESERT THROUGHOUT WEEK-2, WHERE TOOLS HAVE A 20-40% CHANCE
OF EXCEEDING THE 85TH PERCENTILE. THE GEFS AND ECENS PETS SHOW AT LEAST A 20%
CHANCE OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE AND 95 DEG F
ACROSS THE NORTHERN HIGH PLAINS AT THE BEGINNING OF WEEK-2, ESPECIALLY FOR AUG
24-25. DUE TO THE EXPECTATION OF POSSIBLE HEAT BEING FAIRLY SHORT-LIVED AND
CONTINUED HIGH MODEL UNCERTAINTY AN ASSOCIATED HEAT HAZARD IS NOT DESIGNATED AT
THIS TIME FOR THIS REGION.
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
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 SHIFTED MORE OFFSHORE IN THE LATEST
GUIDANCE.
AS OF 11AM PDT, THE NATIONAL HURRICANE CENTER (NHC) INDICATES AN AREA OF LOW
PRESSURE OFFSHORE OF SOUTHWESTERN MEXICO WITH A 60% CHANCE OF FORMING INTO A
TROPICAL CYCLONE IN THE NEXT 7 DAYS. SHOULD THIS OCCUR, THERE IS INCREASED
POTENTIAL FOR ENHANCED MONSOONAL MOISTURE INTO THE SOUTHWEST, WHICH COULD
RESULT IN LOCALIZED HEAVY PRECIPITATION ACROSS THE FOUR CORNERS, WITH THE GEFS
ENSEMBLE MEAN FAVORING THE HIGHEST CHANCES IN THE WESTERN PORTION OF THIS
REGION.THERE IS TOO MUCH MODEL UNCERTAINTY TO POST AN ASSOCIATED HAZARD AT THIS
TIME.
THE CENTRAL PACIFIC HURRICANE CENTER IS FORECASTING A 60% CHANCE OF TROPICAL
CYCLONE FORMATION IN THE CENTRAL PACIFIC AS OF 2AM HST. SHOULD A CYCLONE 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 IS PREDICTED TO SHIFT EASTWARD AND AMPLIFY OVER INTERIOR
ALASKA BY THE MIDDLE OF WEEK-2, WHICH COULD 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 BUT
WILL BE MONITORED FOR POSSIBLE IMPACTS IN THE UPCOMING DAYS.
FORECASTER: MELISSA OU
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