724
FXUS21 KWNC 111851
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 11 2024
SYNOPSIS: A HEAT WAVE IS FORECAST TO BE ONGOING ACROSS PORTIONS OF THE MIDWEST,
MID-ATLANTIC, AND NORTHEAST AT THE OUTSET OF WEEK-2 ASSOCIATED WITH AMPLIFIED
MID-LEVEL HIGH PRESSURE OVER THE EASTERN U.S. BY THE MIDDLE OF THE PERIOD, THIS
FEATURE IS FORECAST TO BROADEN FURTHER, INCREASING EXCESSIVE HEAT CHANCES
ACROSS PARTS OF THE INTERIOR WEST AND THE CALIFORNIA CENTRAL VALLEY. ENHANCED
SOUTHERLY FLOW AND AN INFLUX OF TROPICAL MOISTURE FAVOR ELEVATED CHANCES OF
HEAVY PRECIPITATION AND POTENTIAL FLOODING NEAR THE GULF OF MEXICO COAST,
ALTHOUGH THERE IS UNCERTAINTY REGARDING TIMING AND ORIENTATION OF THE HEAVIEST
PRECIPITATION.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE MIDWEST, WED-SUN, JUN
19-23.
MODERATE RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE NORTHEAST AND
MID-ATLANTIC, WED-FRI, JUN 19-21.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL AND EASTERN CONUS,
WED-TUE, JUN 19-25.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE INTERIOR WEST, THU-TUE,
JUN 20-25.
MODERATE RISK OF HEAVY PRECIPITATION ALONG THE WESTERN AND CENTRAL GULF OF
MEXICO COAST, WED-SAT, JUN 19-22.
SLIGHT RISK OF HEAVY PRECIPITATION NEAR THE GULF OF MEXICO COAST, WED-TUE, JUN
19-25.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHERN PLAINS AND
UPPER MISSISSIPPI VALLEY, WED-SUN, JUN 19-23.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE ROCKIES AND HIGH PLAINS,
WED-THU, JUN 19-20.
FLOODING POSSIBLE ACROSS PORTIONS OF THE GULF OF MEXICO COAST.
DETAILED SUMMARY
FOR FRIDAY JUNE 14 - TUESDAY JUNE 18:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JUNE 19 - TUESDAY JUNE 25: ANOMALOUS RIDGING IS FORECAST OVER THE
CENTRAL AND EASTERN CONTIGUOUS U.S. (CONUS) DURING WEEK-2. THIS FAVORS
INCREASED POTENTIAL FOR EXCESSIVE HEAT ACROSS THE MIDWEST, MID-ATLANTIC, AND
NORTHEAST. THE ECMWF IS MORE ROBUST WITH THE HEAT COMPARED TO THE GEFS, AND
THIS IS EVIDENT IN BOTH THE PROBABILISTIC EXTREMES TOOL (PET), WHICH DEPICTS
GREATER THAN A 60 PERCENT CHANCE MAXIMUM TEMPERATURES EXCEED THE 85TH
CLIMATOLOGICAL PERCENTILE, AND THE UNCALIBRATED ENSEMBLE WHICH DEPICT SOME
AREAS OF THE OHIO VALLEY AND MID-ATLANTIC WITH TEMPERATURES IN THE MID- TO
POSSIBLY UPPER 90S DEG F. THE GEFS IS GENERALLY A FEW DEGREES COOLER THAN THE
ECMWF AND THE PROBABILITIES FOR REACHING THE 85TH CLIMATOLOGICAL PERCENTILE IN
THE GEFS PET ARE LOWER THAN IN THE ECMWF PET. THE NATIONAL BLEND OF MODELS
(NBM) ALSO INDICATES RECORD HIGH DAILY TEMPERATURES, AS WELL AS RECORD HIGH
MINIMUM TEMPERATURES. HEAT INDEX VALUES NEAR OR EXCEEDING 100 (105) DEG F ARE
POSSIBLE ACROSS THE MIDWEST AND NORTHEAST (MID-ATLANTIC).
GIVEN THESE SIGNALS, A MODERATE RISK FOR EXCESSIVE HEAT IS POSTED ACROSS THE
PARTS OF THE MID-ATLANTIC AND NORTHEAST EAST OF THE APPALACHIANS, JUN 19-21.
ANOTHER MODERATE RISK FOR EXCESSIVE HEAT IS HIGHLIGHTED ACROSS THE MIDDLE
MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS THROUGH JUN 23 AS THE STRONGEST
RIDGING IS FORECAST TO RETROGRADE WESTWARD BY THE MIDDLE OF WEEK-2, PROVIDING
SOME RELIEF FROM THE HOTTEST TEMPERATURES IN THE EAST, BUT PERSISTING OR
PERHAPS INCREASING THE HEAT ACROSS THE MIDWEST. A BROADER SLIGHT RISK IS POSTED
FROM THE MIDDLE MISSISSIPPI VALLEY THROUGH THE NORTHEAST FOR ALL OF WEEK-2
GIVEN THE FORECAST PERSISTENCE OF THE POSITIVE MID-LEVEL HEIGHT ANOMALIES AND
THE POTENTIAL FOR A LONG DURATION OF ABOVE-NORMAL TEMPERATURES THROUGHOUT THE
SECOND HALF OF JUNE. DRY SOILS ARE OBSERVED ACROSS PARTS OF THE OHIO VALLEY AND
MID-ATLANTIC AND THESE AREAS MAY NEED TO BE MONITORED FOR DROUGHT DEVELOPMENT
GIVEN THE INCREASING TEMPERATURES AND DECREASING PRECIPITATION CHANCES. THE
WESTWARD SHIFT IN RIDGING FAVORS A SUBSEQUENT INCREASE IN EXCESSIVE HEAT
CHANCES ACROSS THE WEST BEGINNING ON DAY-9 (JUN 20), WITH THE GEFS AND ECMWF
PETS DEPICTING AT LEAST A 20 PERCENT CHANCE OF MAXIMUM TEMPERATURES EXCEEDING
THE 85TH CLIMATOLOGICAL PERCENTILE ACROSS PARTS OF THE INTERIOR WEST. THEREFORE
A SLIGHT RISK OF EXCESSIVE HEAT IS HIGHLIGHTED ACROSS PARTS OF THE GREAT BASIN,
ROCKIES, SOUTHWEST, AND CALIFORNIA CENTRAL VALLEY, JUN 20-25.
INCREASED SOUTHERLY FLOW IS PREDICTED ACROSS THE GULF COAST WITH THE GEFS AND
ECMWF ENSEMBLES INDICATING A POTENTIAL INFLUX OF TROPICAL MOISTURE DURING
WEEK-2. THE GEFS HAS TRENDED MORE WESTWARD, DEPICTING THE GREATEST MOISTURE
SURGE INTO THE CENTRAL GULF COAST AS OPPOSED TO FLORIDA, WHICH IS FORECAST TO
HAVE HEAVY RAINFALL DURING WEEK-1. THE ECMWF ENSEMBLE IS EVEN FURTHER TO THE
WEST, ACROSS EASTERN TEXAS AND LOUISIANA. THE LATEST GLOBAL TROPICS HAZARDS
OUTLOOK DEPICTS A 40-60 PERCENT CHANCE OF TC DEVELOPMENT IN THE BAY OF CAMPECHE
DURING WEEK-2, AND THE POTENTIAL DEVELOPMENT OF THIS SYSTEM ALONG WITH THE
TRACK WILL DETERMINE THE LOCATIONS OF GREATEST HEAVY RAINFALL RISK. FOR NOW, A
MODERATE RISK OF HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS THE WESTERN AND
CENTRAL GULF COASTS, JUN 19-22. WHILE NOT ALL LOCATIONS ARE LIKELY TO BE
IMPACTED, THE INCREASING SIGNAL FOR A SIGNIFICANT RAINFALL EVENT IN SOME AREAS
WARRANTS THE ADDITION OF THE MODERATE RISK, AND THIS REGION MAY BE FURTHER
REFINED SHOULD MODELS COME INTO BETTER AGREEMENT. A BROADER SLIGHT RISK IS
POSTED ALONG THE ENTIRE GULF COAST, INCLUDING FLORIDA AND PARTS OF THE LOWER
MISSISSIPPI VALLEY AND SOUTHEAST, FOR ALL OF WEEK-2. A FLOODING POSSIBLE HAZARD
IS ALSO HIGHLIGHTED ACROSS PARTS OF EASTERN TEXAS AND SOUTHERN LOUISANNA GIVEN
ALREADY HIGH GAUGE LEVELS. ONGOING HEAVY RAINFALL ACROSS SOUTH FLORIDA IN
WEEK-1 MAY ENHANCE FLOODING CONCERNS ACROSS THE REGION INTO WEEK-2, ALTHOUGH
THERE IS MORE UNCERTAINTY GIVEN THE WESTWARD SHIFT IN THE HEAVIEST
PRECIPITATION.
ANOTHER SLIGHT RISK FOR HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY ALONG THE PERIPHERY OF THE RIDGE AXIS, JUN
19-23. TROUGHING UPSTREAM OVER THE WEST EARLY IN THE PERIOD SUPPORTS INCREASED
THUNDERSTORM ACTIVITY ALONG A FRONTAL BOUNDARY SET-UP OVER THE REGION. ANY
STORMS COULD RESULT IN LOCALIZED HEAVY RAINFALL AND FLASH FLOODING. THIS
TROUGHING ALSO SUPPORTS A SLIGHT RISK OF EPISODIC HIGH WINDS ACROSS PORTIONS OF
THE INTERIOR WEST AND HIGH PLAINS, JUNE 19-20. THE ECMWF PET INDICATES AT LEAST
A 20 PERCENT CHANCE OF WIND SPEEDS EXCEEDING THE 85TH PERCENTILE AND 20 MPH
OVER THE HIGHLIGHTED AREA. ANTICIPATED HOT, DRY, AND WINDY CONDITIONS MAY
INCREASE WILDFIRE RISK ACROSS THESE AREAS. AS THE TROUGH LIFTS OUT AND THE
RIDGE BROADENS, THE WIND RISK IS FORECAST TO SUBSIDE.
FORECASTER: THOMAS COLLOW
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