255
FXUS21 KWNC 211755
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 21 2026
SYNOPSIS: MID-LEVEL HIGH PRESSURE OVER THE SOUTHEASTERN CONUS BRINGS AN
INCREASED RISK OF EXTREME HEAT FROM THE FLORIDA PENINSULA NORTHWARD INTO THE
SOUTHERN AND MIDDLE ATLANTIC REGIONS THROUGHOUT WEEK-2. MID-LEVEL HIGH PRESSURE
ALSO BUILDS WESTWARD AND NORTHWESTWARD ACROSS THE GULF COAST STATES AND
SOUTHERN AND CENTRAL PLAINS, INCREASING THE RISK OF EXTREME HEAT ACROSS THOSE
AREAS. MEANWHILE, EARLY IN THE PERIOD, A SURFACE LOW OVER SOUTH-CENTRAL CANADA
AND UPSTREAM MID-LEVEL LOW PRESSURE, COMBINED WITH ENHANCED MOISTURE TRANSPORT
FROM THE SOUTH SUPPORT AN INCREASED RISK OF HEAVY PRECIPITATION ACROSS PARTS OF
THE MIDDLE AND UPPER MISSISSIPPI VALLEY AND ADJACENT AREAS.
HAZARDS
MODERATE RISK OF EXTREME HEAT FOR THE MID-ATLANTIC REGION, MON-THU, JUN 29-JUL
2.
SLIGHT RISK OF EXTREME HEAT FOR THE CENTRAL HIGH PLAINS, SOUTHERN PLAINS, GULF
COAST STATES, SOUTHEAST, AND MID-ATLANTIC, MON-SUN, JUN 29-JUL 5.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE UPPER AND MIDDLE MISSISSIPPI VALLEY,
WESTERN GREAT LAKES REGION, AND LOWER OHIO VALLEY, MON-WED, JUN 29-JUL 1.
DETAILED SUMMARY
FOR WEDNESDAY JUNE 24 - SUNDAY JUNE 28:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR MONDAY JUNE 29 - SUNDAY JULY 05: MID-LEVEL HEIGHT ANOMALY FORECASTS FROM
THE GLOBAL ENSEMBLE FORECAST SYSTEM (GEFS), EUROPEAN ENSEMBLE (ECENS), AND
CANADIAN ENSEMBLE (CMCE) FAVOR A RIDGE OVER THE EAST-CENTRAL MID-LATITUDE
PACIFIC, A TROUGH CENTERED NEAR THE WEST COAST, AND A ZONALLY ELONGATED RIDGE
OVER THE REMAINDER OF THE CONUS (GEFS AND CMCE). REGARDING THIS LAST FEATURE,
THE ECENS PREDICTS A MORE AMPLIFIED RIDGE CENTERED OVER THE CENTRAL STATES AND
A WEAK TROUGH OFF THE EASTERN SEABOARD. THE RIDGING FORECAST OVER THE SOUTHWEST
IS CONDUCIVE TO THE ONSET OF THE SUMMER MONSOON, WITH THE PROBABILISTIC
EXTREMES TOOL (PET) PRECIPITATION GUIDANCE FROM BOTH THE GEFS AND ECENS
FORECASTING ANYWHERE UP TO A HALF-INCH OF RAIN. WELL TO THE NORTH, WEAK
TROUGHS ARE PREDICTED NEAR THE WEST COAST OF ALASKA AND OVER SOUTHEAST ALASKA.
AT THE BEGINNING OF WEEK-2, A RESPECTABLE TROUGH PREDICTED OVER THE NORTHERN
ROCKIES AND NORTHERN PLAINS IS FORECAST TO RAPIDLY WEAKEN. THE MID-LEVEL RIDGE
OVER THE EAST IS EXPECTED TO SHIFT WESTWARD WITH ITS AXIS REACHING THE GREAT
PLAINS. POSITIVE HEIGHT ANOMALIES OF 60-120 METERS ARE FORECAST FROM THE
NORTHERN ROCKIES TO THE UPPER GREAT LAKES REGION, AND AS FAR SOUTH AS THE
CENTRAL PLAINS. IN ADDITION, A 594-DM HEIGHT CONTOUR IS DEPICTED OVER THE FOUR
CORNERS REGION (CMCE IS SHIFTED SLIGHTLY EAST COMPARED TO THE OTHER ENSEMBLE
MEANS), WHICH IS CONSISTENT WITH THE CLIMATOLOGICAL ONSET OF THE SOUTHWEST
SUMMER MONSOON.
AS MID-LEVEL RIDGING BUILDS NORTHWARD AND NORTHWESTWARD FROM THE GENERAL
VICINITY OF FLORIDA, TEMPERATURES ARE EXPECTED TO RISE QUICKLY ALONG THE
EASTERN SEABOARD, GULF COAST, SOUTHERN PLAINS, AND CENTRAL HIGH PLAINS. FOR
THESE AREAS, A SLIGHT RISK OF EXTREME HEAT IS POSTED FOR THE DURATION OF
WEEK-2. A MODERATE RISK OF EXTREME HEAT IS DESIGNATED FOR THE MID-ATLANTIC
REGION, JUN 29-JUL 2. THIS INCLUDES MAJOR CITIES LIKE PHILADELPHIA, BALTIMORE,
WASHINGTON, D.C., RICHMOND, RALEIGH, AND CHARLOTTE. ALONG THE EASTERN SEABOARD,
ACTUAL (I.E. DRY BULB) TEMPERATURES IN WASHINGTON, D.C. AND PHILADELPHIA ARE
FORECAST TO REACH 95 DEG F, WITH HEAT INDEX VALUES CLIMBING TO NEAR 105 DEG F.
THIS IS SUPPORTED BY THE GEFS, ECENS, AND CMCE PETS , UNCALIBRATED TEMPERATURE
GUIDANCE, AND A SKILL-WEIGHTED, BIAS-CORRECTED EXTREME HEAT TOOL WHICH USES THE
GEFS AND ECENS. THE PETS ALSO INDICATE A 20 PERCENT CHANCE OF TEMPERATURES
REACHING 95 DEG F IN THE WASHINGTON, D.C. AREA, ESPECIALLY DURING THE EARLY AND
MIDDLE STAGES OF WEEK-2. THE 06Z DETERMINISTIC GFS MODEL RUN DEPICTS EXTENDED
PERIODS OF SOUTHWESTERLY SURFACE FLOW DURING THIS PERIOD AND DEW POINTS RANGING
FROM THE UPPER 60'S TO NEAR 70 DEG F FOR THE MID-ATLANTIC REGION. FOR THE GULF
COAST AREA, DEW POINT TEMPERATURES MAY BE A BIT HIGHER (70-75 DEG F), THOUGH
ACTUAL AIR TEMPERATURES SHOULD BE COMPARABLE TO THOSE IN THE MID-ATLANTIC. OVER
THE SOUTHERN PLAINS AND CENTRAL HIGH PLAINS, AIR TEMPERATURES ARE FORECAST TO
TOP OUT NEAR 100 DEG F, WITH MAXIMUM HEAT INDEX VALUES OF 105 DEG F. THE
EXCEPTION APPLIES TO THE RED RIVER VALLEY OF THE SOUTH STRADDLING TEXAS AND
OKLAHOMA, WHERE HEAT INDEX VALUES MAY REACH 110 DEG F. THE SAME TEMPERATURE
TOOLS CONSIDERED FOR THE EASTERN SEABOARD WERE USED FOR THE PLAINS. THE
DESIGNATED EXTREME HEAT REGION OVER THE PLAINS DOES NOT INCLUDE AREAS WITH
ABOVE-NORMAL SOIL MOISTURE (SUCH AS SOUTHERN TEXAS) OR AREAS WHERE SIGNIFICANT
PRECIPITATION (RANGING FROM 1-7 INCHES), IS PREDICTED TO FALL IN THE PRIOR
WEEK-1 TIME FRAME (I.E. EASTERN OKLAHOMA AND EASTERN KANSAS).
THE PREDICTED PRESENCE OF AN UPSTREAM MID-LEVEL TROUGH OVER THE NORTHERN
ROCKIES AND NORTHERN PLAINS AND A SURFACE LOW OVER SOUTH-CENTRAL CANADA WITH
TRAILING FRONT FAVORS A SLIGHT RISK OF HEAVY PRECIPITATION FOR THE UPPER AND
MIDDLE MISSISSIPPI VALLEY, WESTERN GREAT LAKES REGION, AND LOWER OHIO VALLEY,
JUN 29-JUL 1. THIS REGION IS ALSO CONSISTENT WITH WHERE THE PETS FAVOR 1-INCH
OR MORE OF PRECIPITATION. IN PERCENTILE SPACE, THE ECENS PET ALSO INDICATES AT
LEAST A 20 PERCENT CHANCE OF EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE,
WHILE THE GEFS PET IS NOT AS CONFIDENT. THE UNCALIBRATED PRECIPITATION TOOLS
BASED ON THE GEFS AND ECENS MODELS FAVOR A 20-40 PERCENT CHANCE OF AMOUNTS
EXCEEDING 1-INCH. ANOTHER CONSIDERATION IS THE ENHANCED LIKELIHOOD OF MCS
ACTIVITY IN THIS GENERAL AREA, ESPECIALLY DURING THE SECOND HALF OF THE PERIOD
WHEN THE MID-LEVEL RIDGE IS FORECAST TO HAVE SHIFTED TO THE GREAT PLAINS. WITH
THE SOUTHERN PORTION OF THE WESTERLIES THEN FAVORED OVER THE NORTH-CENTRAL
STATES AT THIS TIME OF YEAR, THERE IS AN ELEVATED CHANCE OF THUNDERSTORM
CLUSTERS GENERALLY FORMING NEAR THE RIDGE CREST AND MOVING SOUTHEASTWARD
(DOWNSTREAM) THROUGH THIS REGION. SCATTERED AREAS OF FLOODING ARE POSSIBLE
WHERE THERE ARE LOCALIZED HEAVIER RAINFALL TOTALS, BUT CHANCES ARE NOT HIGH
ENOUGH TO JUSTIFY A SPECIFIC AREA AT RISK OF BROADSCALE FLOODING. ELSEWHERE, AN
INCH OF PRECIPITATION IS INDICATED BY THE PET GUIDANCE ACROSS THE FLORIDA
PENINSULA, THOUGH IT IS PREDICTED TO FALL OVER A 7-DAY PERIOD, NOT A 3-DAY
PERIOD AS IS REQUIRED FOR HAZARDOUS DESIGNATION.
NO HAZARDS ARE POSTED OVER ALASKA, BUT THERE IS THE POTENTIAL FOR INCREASED
THUNDERSTORM ACTIVITY AND ASSOCIATED LIGHTNING THAT COULD TRIGGER WILDFIRES.
FORECASTER: ANTHONY ARTUSA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page