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FXUS21 KWNC 131948
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 13 2023
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS PREDICTED TO PERSIST FROM WEEK-1
THROUGHOUT WEEK-2 ACROSS THE SOUTH-CENTRAL CONTIGUOUS U.S. (CONUS), SUPPORTING
CONTINUED INCREASED CHANCES FOR EXCESSIVE HEAT ACROSS PARTS OF THE REGION
THROUGHOUT MUCH OF THE PERIOD. THERE IS A POTENTIAL FOR SOME AREAS TO
EXPERIENCE NEAR RECORD TEMPERATURES IN THE TRIPLE DIGITS, ESPECIALLY AT THE
BEGINNING OF WEEK-2, ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY.
FURTHER NORTH, MID-LEVEL HIGH PRESSURE IS GENERALLY FORECAST ACROSS THE UPPER
MIDWEST AND NORTHEAST, FAVORING ABOVE NORMAL TEMPERATURES ACROSS PARTS OF THESE
REGIONS. SNOWMELT SEASON CONTINUES FOR PORTIONS OF THE WEST AFTER EXCEPTIONAL
WINTER ACCUMULATIONS, LEADING TO THE CONTINUED POTENTIAL FOR FLOODING.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT ACROSS PARTS OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY, WED-SAT, JUN 21-24.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PARTS OF THE SOUTH-CENTRAL CONUS, LOWER
MISSISSIPPI VALLEY, AND MISSOURI, WED-TUE, JUN 21-27.
POSSIBLE FLOODING FOR PORTIONS OF CALIFORNIA, NEVADA, UTAH, WYOMING, AND IDAHO.
POSSIBLE FLOODING ALONG PORTIONS OF THE JAMES RIVER IN SOUTH DAKOTA.
RAPID ONSET DROUGHT RISK ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY.
DETAILED SUMMARY
FOR FRIDAY JUNE 16 - TUESDAY JUNE 20:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JUNE 21 - TUESDAY JUNE 27: THE PRIMARY HAZARDS CONCERN IS THE
CONTINUED INCREASED RISK FOR EXCESSIVE HEAT ACROSS THE SOUTH-CENTRAL CONUS AND
LOWER MISSISSIPPI VALLEY DURING WEEK-2. THE 0Z GEFS, ECMWF, AND CANADIAN
ENSEMBLE MEANS INDICATE STRONGER POSITIVE HEIGHT DEPARTURES OVER THIS REGION
COMPARED TO YESTERDAY, TRANSLATING TO INCREASED SIGNALS FOR EXCESSIVE HEAT IN
THE TOOLS. TODAY THE GEFS PROBABILISTIC EXTREMES TOOL (PET) INDICATES AT LEAST
A 40% CHANCE OF TEMPERATURES EXCEEDING THE 85TH PERCENTILE, CLIMATOLOGICALLY,
FROM DAYS 8 TO 11 (JUN 21-24) FOR TEXAS, WHEREAS YESTERDAY IT ONLY INDICATED
THIS SIGNAL FOR DAY 8. THE ECMWF PET SHOWS HIGHER PROBABILITIES THAN THE GEFS
ON DAY 8 (AT LEAST A 60% CHANCE OF TEMPERATURES EXCEEDING THE 85TH PERCENTILE)
OVER CENTRAL AND SOUTHERN TEXAS, BUT DROPS TO 30% CHANCES BY DAY 11. GIVEN GOOD
ALIGNMENT IN THE TEMPERATURE AND HEAT TOOLS, THE MODERATE RISK OF EXCESSIVE
HEAT IS CONTINUED FOR THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, SLIGHTLY
EXPANDED TO WESTERN TEXAS, JUN 21-24. A BROADER SLIGHT RISK AREA IS HIGHLIGHTED
ACROSS PARTS OF THE SOUTH-CENTRAL CONUS, LOWER MISSISSIPPI VALLEY, AND
MISSOURI, THROUGHOUT WEEK-2, WHERE MULTIPLE TOOLS SHOW AT LEAST A 20% CHANCE OF
HEAT INDEX VALUES EXCEEDING THE 90TH PERCENTILE. THE NATIONAL BLEND OF MODELS
(NBM) CONTINUES TO INDICATE THE POTENTIAL FOR NEAR RECORD BREAKING TEMPERATURES
IN THE TRIPLE DIGITS (GREATER THAN 110 DEG F ACROSS SOUTHERN TEXAS AND 105 DEG
F ELSEWHERE ACROSS THE MODERATE RISK AREA).
MID-LEVEL RIDGING IS ALSO FORECAST TO BUILD ACROSS THE UPPER MIDWEST,
INCREASING THE LIKELIHOOD FOR ABOVE NORMAL TEMPERATURES DURING WEEK-2. THE GEFS
AND ECMWF PET SHOW AT LEAST A 30% CHANCE OF TEMPERATURES EXCEEDING THE 85TH
PERCENTILE ACROSS THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES FROM THE
BEGINNING TO MIDDLE OF WEEK-2, WITH CHANCES GRADUALLY DECREASING OVER TIME.
TEMPERATURES IN THESE AREAS ARE ANTICIPATED TO REMAIN BELOW 90 DEG F,
PRECLUDING A HAZARD FROM BEING POSTED FOR THIS REGION.
GIVEN THE EXCESSIVE HEAT FORECAST ALONG WITH ANTECEDENT DRY CONDITIONS, RAPID
ONSET DROUGHT (ROD) RISK REMAINS ELEVATED ACROSS PORTIONS OF THE LOWER
MISSISSIPPI VALLEY WHERE SOIL MOISTURE VALUES HAVE DROPPED BELOW THE 30TH
CLIMATOLOGICAL PERCENTILE IN SOME AREAS. ADDITIONALLY, ANTICIPATED HOT AND DRY
CONDITIONS MAY ELEVATE WILDFIRE RISK ACROSS PARTS OF TEXAS AND LOUISIANA,
ESPECIALLY WHERE THE NATIONAL INTERAGENCY FIRE CENTER (NIFC) INDICATES MODERATE
TO HIGH RISK OF SIGNIFICANT FIRE POTENTIAL BY THE END OF WEEK-1.
RECENT DETERMINISTIC AND ENSEMBLE MODEL GUIDANCE CONTINUES TO SHOW SOME
POTENTIAL OF A SURFACE LOW FORMING NEAR OR ALONG THE COAST OF THE CAROLINAS
FROM THE BEGINNING TO MIDDLE OF WEEK-2, WHICH COULD BRING ENHANCED
PRECIPITATION TO PARTS OF THE MID-ATLANTIC AND SOUTHEAST. THE ECMWF, AND
CANADIAN PET SHOW AT LEAST A 20% CHANCE OF 3-DAY RAINFALL EXCEEDING THE 85TH
PERCENTILE AND ONE INCH ACROSS THESE AREAS. HOWEVER, THE GEFS NO LONGER REACHES
THESE THRESHOLDS UNLIKE YESTERDAY. THERE CONTINUES TO BE TOO MUCH UNCERTAINTY
AT THIS TIME REGARDING THE DETAILS OF THIS FEATURE TO DESIGNATE A RELATED HEAVY
PRECIPITATION HAZARD AT THIS TIME.
SNOWMELT SEASON CONTINUES ACROSS PORTIONS OF 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, GREAT BASIN, AND NORTHERN
ROCKIES, FLOODING MAY CONTINUE TO OCCUR ALONG SOME RIVERS AND CREEKS, AND IN
AREAS ADJACENT TO THE HIGHER ELEVATIONS. THERE HAS BEEN A REDUCTION IN COVERAGE
OF POSSIBLE FLOODING ACROSS THE WEST BASED ON DECREASING SNOWPACK. POSSIBLE
FLOODING ALSO REMAINS ACROSS NORTHERN PARTS OF THE JAMES RIVER IN SOUTH DAKOTA
AS RIVER LEVELS ARE RECEDING SLOWER DUE TO SATURATED GROUND CONDITIONS AND
RELATIVELY FLAT TOPOGRAPHY.
WEAK POSITIVE MID-LEVEL HEIGHT DEPARTURES CONTINUE TO BE FAVORED ACROSS MOST OF
ALASKA (EXCLUDING WESTERN ALEUTIANS), SUPPORTING NEAR TO ABOVE NORMAL
TEMPERATURES ACROSS MUCH OF THE CENTRAL AND EASTERN MAINLAND AND SOUTHEAST
ALASKA, WITH BELOW NORMAL TEMPERATURES FORECAST ACROSS THE WESTERN MAINLAND. A
RELATIVELY INACTIVE STORM PATTERN IS ANTICIPATED FOR ALASKA PRECLUDING ANY
HAZARDS DESIGNATED FOR THE STATE.
FORECASTER: MELISSA OU
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