281
FXUS21 KWNC 261826
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 26 2025
SYNOPSIS: SURFACE LOW PRESSURE MAY FORM IN THE WESTERN ATLANTIC AND MOVE ALONG
PARTS OF THE EASTERN SEABOARD EARLY IN THE PERIOD, POSSIBLY BRINGING HEAVY
PRECIPITATION AND HIGH WINDS NEAR THE COAST, ALTHOUGH THE EVOLUTION OF ANY
SYSTEM THAT DOES DEVELOP IS HIGHLY UNCERTAIN. FARTHER SOUTH, A FEW WAVES OF LOW
PRESSURE MAY FORM ALONG A WAVERING FRONTAL SYSTEM FROM CENTRAL TEXAS THROUGH
THE CENTRAL GULF COAST AND THE SOUTHEAST, KEEPING A RISK OF SCATTERED HEAVY
RAINS THERE ALL WEEK. IN THE SOUTHWEST, POTENTIAL TROPICAL CYCLONE DEVELOPMENT
WEST OF MEXICO COULD ENHANCE TROPICAL MOISTURE PUSHING INTO THE SOUTHWEST,
INCREASING THE POTENTIAL FOR EPISODES OF LOCALLY HEAVY PRECIPITATION.
HAZARDS
SLIGHT RISK OF HIGH WINDS ALONG PARTS OF THE EAST COAST, WED, SEP 3.
SLIGHT RISK OF HEAVY PRECIPITATION ALONG PARTS OF THE EAST COAST, WED, SEP 3.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHEAST, GULF COAST,
AND LOWER MISSISSIPPI VALLEY, WED-TUE, SEP 3-9.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHWEST, WED-TUE, SEP
3-9.
SLIGHT RISK OF HEAVY PRECIPITATION IN WESTERN PARTS OF THE MIDDLE MISSISSIPPI
VALLEY, THE ADJACENT GREAT PLAINS, AND THE SOUTH-CENTRAL CONUS, WED-FRI, SEP
3-5.
DETAILED SUMMARY
FOR FRIDAY AUGUST 29 - TUESDAY SEPTEMBER 02:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY SEPTEMBER 03 - TUESDAY SEPTEMBER 09: AT THE OUTSET OF WEEK-2, THE
DETERMINISTIC MODELS AND ENSEMBLE MEANS ALL HINT AT SOME SORT OF ANOMALOUSLY
LOW SURFACE PRESSURE EAST OF THE ATLANTIC COAST WITH HIGHER-THAN-USUAL SURFACE
PRESSURE OVER THE NORTHEASTERN CONUS. THE ENSEMBLE MEANS SHOW A VERY WEAK
SET-UP, INDICATIVE OF MEMBER-TO-MEMBER DIFFERENCES IN THE HANDLING OF THIS
SYSTEM, BUT THE DETERMINISTIC ECMWF AND GFS MODELS INDICATE THAT THIS SYSTEM
COULD BE A LITTLE STRONGER THAN THE ENSEMBLE MEANS IMPLY. THE MODELS WITH THE
STRONGEST SOLUTIONS YESTERDAY, SUCH AS THE 6Z GFS, HAVE COME INTO BETTER
ALIGNMENT WITH THE OTHER PREVAILING DETERMINISTIC FORECASTS IN KEEPING ANY
STORM THAT FORMS A BIT WEAKER AND FARTHER EAST. HOWEVER, DESPITE THE BROAD
CONSENSUS FAVORING A WEAKER SYSTEM OFF THE COAST, THE UNCERTAINTY LEAVES ENOUGH
POTENTIAL FOR THE STORM TO BE A LITTLE STRONGER THAN THE CONSENSUS AND CLOSER
TO THE COAST. TO WIT, SLIGHT RISKS FOR HEAVY PRECIPITATION AND HIGH WINDS ARE
MAINTAINED NEAR THE MID-ATLANTIC AND NORTHEAST COASTS FOR THE FIRST DAY OF
WEEK-2 BEFORE THE POTENTIAL STORM SYSTEM MOVES FAIRLY QUICKLY OUT TO SEA.
THE HIGH PRESSURE OVER THE NORTHEASTERN CONUS IS HEADING TOWARD ATLANTIC CANADA
AT THE OUTSET OF WEEK-2. MEANWHILE, A SECOND HIGH PRESSURE SYSTEM IS EXPECTED
TO PUSH INTO THE CENTRAL AND EASTERN CONUS THROUGH THE MIDDLE OF WEEK-2. THE
COLD FRONT ON THE LEADING EDGE OF THIS SECOND HIGH PRESSURE SYSTEM COULD SERVE
AS A FOCUS FOR HEAVY PRECIPITATION. DURING THE FIRST FEW DAYS OF THE WEEK, THE
PROBABILISTIC EXTREMES TOOLS (PETS) FROM THE ECENS AND GEFS SHOW A 20 TO 30
PERCENT CHANCE FOR TOTALS EXCEEDING AN INCH AND IN THE TOP 15TH PERCENTILE OF
THE CLIMATOLOGICAL ENVELOPE IN PARTS OF THE CENTRAL AND SOUTH-CENTRAL CONUS,
PROMPTING A SLIGHT RISK OF HEAVY PRECIPITATION THERE FOR THE FIRST FEW DAYS OF
WEEK-2. AS THIS FRONT TRAVELS FARTHER EAST, SOME DETERMINISTIC MODELS FORECAST
A LOW PRESSURE CENTER TO DEVELOP IN THE MIDDLE OHIO VALLEY AND TRAVEL
NORTHEASTWARD. THIS WOULD ENHANCE PRECIPITATION TOTALS IN THIS REGION TOWARD
MIDWEEK RELATIVE TO AMOUNTS FARTHER SOUTHWEST IN THE LOWER OHIO VALLEY AND
ADJACENT AREAS. HOWEVER, THE PETS ARE ENTIRELY UNIMPRESSIVE HERE, AND MOST
DETERMINISTIC MODELS ARE NOT BRINGING IN ENOUGH RAINFALL TO JUSTIFY ANY HEAVY
PRECIPITATION HAZARD IN THE NORTHEAST, ALTHOUGH THE SITUATION WILL NEED TO BE
MONITORED.
A WAVERING QUASI-STATIONARY FRONT IS FORECAST TO BE DRAPED FROM THE SOUTH
ATLANTIC REGION WESTWARD ALONG OR NEAR THE CENTRAL GULF COAST AND INTO EASTERN
PART OF THE LOWER MISSISSIPPI VALLEY AND EASTERN TEXAS. MOST MODELS FAVOR THIS
FRONT BECOMING A FOCUS FOR PERIODIC HEAVY PRECIPITATION, BUT THEY DIVERGE ON
THE DETAILS. THE TIMING, LOCATION, AND QUANTITY OF PRECIPITATION ARE ALL IN
QUESTION, MAGNIFIED BY MODEL INCONSISTENCIES REGARDING POTENTIAL SURFACE LOW
PRESSURE DEVELOPMENT. THE PROBABILISTIC EXTREMES TOOLS (PETS) DERIVED FROM THE
ENSEMBLES ALL SHOW RELATIVELY WEAK SIGNALS FOR HEAVY RAINFALL POTENTIAL,
GENERALLY FOCUSED OVER THE CENTRAL AND WESTERN GULF COAST. TODAY, DETERMINISTIC
MODELS SHOW SPOTTY HEAVY RAINFALL DEVELOPING IN THE SOUTH ATLANTIC REGION LATER
IN THE PERIOD, AND KEEP MUCH OF FLORIDA IN UNSETTLED EASTERLY FLOW ALL WEEK.
ALL THINGS CONSIDERED, A SLIGHT RISK FOR HEAVY PRECIPITATION IS POSTED FOR THE
ENTIRETY OF WEEK-2 IN THESE AREAS. IT SHOULD BE NOTED THAT ANY HEAVY
PRECIPITATION THAT DOES FALL WOULD PROBABLY BE EPISODIC AND NOT CONTINUE
THROUGH ALL OF WEEK-2, AND SHOULD ONLY IMPACT PARTS OF THE REGION ON ANY GIVEN
DAY.
AS OF 11AM PDT ON AUGUST 25, THE NATIONAL HURRICANE CENTER IS TRACKING TROPICAL
STORM JULIETTE SEVERAL HUNDRED MILES OFFSHORE OF SOUTHWESTERN MEXICO. JULIETTE
IS EXPECTED TO TRACK NORTHWESTWARD THROUGH LATE AUGUST BEFORE WEAKENING, BUT
SOME MEMBERS OF THE ECENS AND GEFS, IN ADDITION TO THE DETERMINISTIC GFS, SHOW
THE POSSIBILITY OF ONE OR TWO ADDITIONAL TROPICAL CYCLONES FORMING IN THE EAST
PACIFIC DURING THE ENSUING SEVEN TO TEN DAYS. AT LEAST ONE OF THESE SYSTEMS MAY
TRACK CLOSE TO THE BAJA PENINSULA. THIS TRACK WOULD INCREASE THE POTENTIAL FOR
SURGES OF ENHANCED LOW TO MID-LEVEL TROPICAL MOISTURE NORTHWARD INTO THE DESERT
SOUTHWEST. THE CHANCES FOR HEAVY PRECIPITATION ARE NOT ROBUST ACCORDING TO THE
PETS, ALTHOUGH TODAY’S ECENS PET FOR THE FIRST 3 DAYS OF WEEK-2 SHOWS 20 TO 30
PERCENT CHANCES FOR PRECIPITATION AMONG THE TOP 15TH PERCENTILE OF THE
CLIMATOLOGICAL ENVELOPE AND EXCEEDING 0.5 INCH, WHICH WAS NOT THE CASE
YESTERDAY. IN ADDITION, THE DETERMINISTIC MODELS ALL SHOW PERIODS OF ENHANCED
CONVECTION AND SPOTTY HEAVY RAINFALL AT DIFFERENT TIMES THROUGHOUT THE WEEK.
OVERALL, THERE IS ENOUGH SUPPORT FROM THE GUIDANCE TO JUSTIFY A SLIGHT RISK OF
HEAVY PRECIPITATION FOR MOST OF ARIZONA AND SOME ADJACENT LOCATIONS. GIVEN THE
RANGE OF MODEL SOLUTIONS REGARDING THE TIMING OF TROPICAL MOISTURE INFLUX, AND
NO CONSENSUS ON THE TRACK OR TIMING OF ANY TROPICAL CYCLONES THAT FORM WEST OF
MEXICO, THE RISK IS MAINTAINED FOR ALL OF WEEK-2.
ALTHOUGH ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS THE PACIFIC NORTHWEST AND
NORTHERN INTERMOUNTAIN WEST, HAZARDOUS HEAT BECOMES MUCH LESS LIKELY BY EARLY
SEPTEMBER. THE MOST ANOMALOUS WARMTH IS EXPECTED ACROSS THE INTERIOR AREAS OF
WASHINGTON ALONG WITH SOUTHWESTERN IDAHO. THE ECENS-BASED PET SHOWS A GREATER
THAN 50 PERCENT CHANCE FOR HIGH TEMPERATURES IN THE TOP 15 PERCENT HISTORIC
OCCURRENCES ON SEP 3, BUT THE SAME TOOL SHOWS ONLY A SMALL AREA WHERE THERE IS
AT LEAST A 30% CHANCE OF TEMPERATURES EXCEEDING 95 DEG F OR HIGHER. THE GEFS
PET SHOWS A SIMILAR PATTERN EARLY WEEK-2, BUT THE SIGNAL IS EVEN WEAKER. WITH
LITTLE INDICATION THAT ACTUAL TEMPERATURES WILL EXCEED HAZARDS THRESHOLDS, NO
AREAS ARE DESIGNATED WITH A RISK OF EXTREME HEAT.
ENHANCED SOUTHWESTERLY FLOW IS FORECAST BY MOST MODELS DURING MUCH OF WEEK-2 IN
ALASKA, WITH SURFACE AND MID-LEVEL PRESSURES FORECAST TO BE ANOMALOUSLY HIGH IN
THE NORTH PACIFIC, AND UNUSUALLY LOW OVER NORTHERN ALASKA AND THE ADJACENT
ARCTIC OCEAN. THIS IS LIKELY TO TRIGGER ONE OR MORE SURFACE LOW PRESSURE
SYSTEMS OVER OR NEAR THE STATE THAT COULD BRING HEAVY PRECIPITATION AND HIGH
WINDS TO SOME AREAS. AT THIS TIME, PRECIPITATION AMOUNTS AND WIND SPEEDS SEEM
UNLIKELY TO REACH HAZARDS THRESHOLDS, BUT THE PATTERN DOES IMPLY AT LEAST SOME
POTENTIAL FOR UNSETTLED WEATHER IN PARTS OF THE STATE THROUGH ABOUT MIDWEEK. NO
PRECIPITATION OR WIND HAZARDS ARE POSTED BECAUSE THERE IS NOT ENOUGH AGREEMENT
ON THE TIMING AND LOCATION OF ANY STORMY WEATHER THAT DEVELOPS. MODELS AND THE
PETS ALSO IMPLY THAT PRECIPITATION TOTALS AND WINDS WOULD ONLY MARGINALLY REACH
HAZARDS THRESHOLDS AT BEST, IF STORMY WEATHER DOES DEVELOP. BUT THE SITUATION
WILL CONTINUE TO BE MONITORED.
FORECASTER: RICH TINKER
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