587
FXUS21 KWNC 152026
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 15 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.
PREDICTED BROAD LOW PRESSURE JUST OFF THE SOUTHEAST COAST ELEVATES THE CHANCES
FOR HEAVY RAIN ACROSS PORTIONS OF THIS AREA. ANTICIPATED THUNDERSTORM CLUSTERS
ASSOCIATED WITH THE NORTHERN PORTION OF THE MID-LEVEL HIGH OVER THE
SOUTH-CENTRAL CONUS INCREASE THE ODDS FOR HEAVY PRECIPITATION OVER THE NORTHERN
AND CENTRAL PLAINS. SNOWMELT SEASON CONTINUES FOR PORTIONS OF THE WEST AFTER
EXCEPTIONAL WINTER ACCUMULATIONS, LEADING TO THE CONTINUED POTENTIAL FOR
FLOODING. SOME AREAS ARE ANTICIPATED TO HAVE SOME IMPROVEMENT IN FLOOD
CONDITIONS DUE TO DECREASING SNOWPACK.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT ACROSS PARTS OF SOUTHERN AND WESTERN TEXAS,
FRI-SAT, JUN 23-24.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PARTS OF THE SOUTH-CENTRAL CONUS, LOWER
MISSISSIPPI
VALLEY, AND MISSOURI, FRI-THU, JUN 23-29.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHEAST COAST,
INCLUDING PORTIONS OF FLORIDA, FRI-MON, JUN 23-26.
SLIGHT RISK OF HEAVY PRECIPITATION OVER THE NORTHERN AND CENTRAL PLAINS,
FRI-MON, JUN 23-26.
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.
RAPID ONSET DROUGHT RISK ACROSS NORTHERN AND CENTRAL WISCONSIN.
DETAILED SUMMARY
FOR SUNDAY JUNE 18 - THURSDAY JUNE 22:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY JUNE 23 - THURSDAY JUNE 29: 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 GFS, ECMWF, AND CANADIAN ENSEMBLE
MEANS ARE IN GOOD AGREEMENT INDICATING WEAKENING OF THIS RIDGE SEVERAL DAYS
INTO THE FORECAST PERIOD, WITH THE ECMWF AND GFS ENSEMBLE MEAN SOLUTIONS
FAVORING A WESTWARD EXPANSION AND/OR SHIFT OF THE RIDGE INTO THE DESERT
SOUTHWEST. A WESTWARD SHIFT IN THE RIDGE POSITION MAY PROVIDE SOME RELIEF FROM
THE EXCESSIVE HEAT FOR EASTERN TEXAS AND LOUISIANA BY MID WEEK-2. THE MODERATE
RISK IS CONFINED TO SOUTHERN AND WESTERN PORTIONS OF TEXAS, JUN 23-24, WHERE
CALIBRATED HEAT INDEX TOOLS INDICATE AT LEAST A 40% CHANCE OF EXCEEDING THE
90TH PERCENTILE CLIMATOLOGICALLY. A BROADER SLIGHT RISK AREA IS HIGHLIGHTED
ACROSS PARTS OF THE SOUTH-CENTRAL CONUS, LOWER MISSISSIPPI VALLEY, AND
MISSOURI, THROUGHOUT WEEK-2, WHERE THESE 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
(105-110 DEG F) FOR LOCALES SUCH AS LAREDO AND DEL RIO IN SOUTHERN TEXAS AND
UPPER 90S DEG F FOR LOUISIANA (JUN 23-24).
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. EASTERN PARTS
OF YESTERDAY’S ROD AREA (ACROSS SOUTHERN MISSISSIPPI) WERE REMOVED FROM THE MAP
TODAY, WHERE OVER 2 INCHES OF RAIN HAVE FALLEN IN THE PAST WEEK. ANOTHER ROD
RISK AREA WAS INTRODUCED TODAY TO NORTHERN AND CENTRAL WISCONSIN, WHERE
ABNORMAL DRYNESS HAS RECENTLY EXPANDED, MINOR AMOUNTS OF RAINFALL ARE EXPECTED
THROUGHOUT THE NEXT 2 WEEKS, AND TEMPERATURES EXCEEDING 90 DEG F ARE LIKELY.
VARIOUS ENSEMBLE MEAN AND DETERMINISTIC MODEL SOLUTIONS CONTINUE TO INDICATE
THE DIGGING OF A TROUGH ACROSS THE EAST-CENTRAL CONUS AND EASTERN GULF OF
MEXICO DURING WEEK-2, AND THE PRESENCE OF THE WESTERN PERIPHERY OF THE BERMUDA
HIGH OFF THE SOUTHEAST COAST. IN BETWEEN THESE TWO FEATURES, THERE IS A SLIGHT
RISK OF HEAVY PRECIPITATION (>20% CHANCE OF EXCEEDING THE 85TH CLIMATOLOGICAL
PERCENTILE AND RAINFALL AMOUNTS IN EXCESS OF 1 INCH OVER A 3-DAY PERIOD) ALONG
PORTIONS OF THE SOUTHEAST COAST, INCLUDING CENTRAL PORTIONS OF THE FLORIDA
PENINSULA, JUN 23-26.
MID-LEVEL SHORTWAVE TROUGHS MOVING OVER THE TOP OF THE SOUTH-CENTRAL CONUS
RIDGE ARE EXPECTED TO CONTRIBUTE TOWARD INCREASED MCS (MESOSCALE CONVECTIVE
SYSTEM) ACTIVITY. THE MOST LIKELY REGION INCLUDES THE NORTHERN AND CENTRAL
GREAT PLAINS, WHERE THERE IS A SLIGHT CHANCE (20% OR GREATER) OF 3-DAY
PRECIPITATION AMOUNTS EXCEEDING THE 85TH PERCENTILE AND 1 INCH.
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. IMPROVEMENTS IN FLOOD CONDITIONS ARE
ANTICIPATED BY WEEK-2 ACROSS PARTS OF THE WEST BASED ON DECREASING SNOWPACK.
POSSIBLE FLOODING ALSO REMAINS ACROSS LOCALIZED NORTHERN PARTS OF THE JAMES
RIVER IN SOUTH DAKOTA. MULTIPLE GAUGES ARE ANTICIPATED TO HAVE IMPROVEMENT IN
FLOOD LEVELS BY AND DURING WEEK-2.
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 NORTHEASTERN HALF OF THE MAINLAND AND SOUTHEAST
ALASKA, WITH BELOW NORMAL TEMPERATURES FORECAST ELSEWHERE. A RELATIVELY
INACTIVE STORM PATTERN IS ANTICIPATED FOR ALASKA PRECLUDING ANY HAZARDS
DESIGNATED FOR THE STATE.
FORECASTER: ANTHONY ARTUSA
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