673
FXUS21 KWNC 111838
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MARCH 11 2026
SYNOPSIS: VERY STRONG MID-LEVEL HIGH PRESSURE IS EXPECTED TO DEVELOP OVER THE
INTERIOR WEST TO PROMOTE UNSEASONABLY WARM TEMPERATURES FOR MUCH OF THE WESTERN
U.S. NEXT WEEK. SPRING EXTREME HEAT CONDITIONS ARE POSSIBLE OVER PARTS OF
DESERT SOUTHWEST AS WELL AS INTO PARTS OF SOUTHERN CALIFORNIA WHERE THERE IS
ALSO AN INCREASED RISK OF SANTA ANA WINDS THROUGH THE MIDDLE OF THE PERIOD.
THIS ANOMALOUSLY WARM PATTERN IS LIKELY TO ACCELERATE SPRING SNOWMELT WHERE
SEASONAL SNOWPACK OVER THE HIGHER ELEVATIONS HAS BEEN WELL BELOW NORMAL.
ACROSS THE PACIFIC NORTHWEST, THERE ARE INCREASED CHANCES FOR EPISODES OF WIND
SPEEDS UNDERNEATH AN ENHANCED ONSHORE FLOW REGIME TO THE NORTH OVER
SOUTHWESTERN CANADA. PERSISTENT MID-LEVEL HIGH PRESSURE TO THE WEST OF THE
BERING STRAIT REMAINS FAVORED TO USHER IN BELOW NORMAL AND POTENTIALLY
IMPACTFUL TEMPERATURES, WITH THIS THREAT GRADUALLY EASING FOR MUCH OF ALASKA
LATER IN WEEK-2.
HAZARDS
MODERATE RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE GREAT
BASIN, ROCKIES, CALIFORNIA, AND DESERT SOUTHWEST, THU-FRI, MAR 19-20.
SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE WESTERN CONUS,
THU-MON, MAR 19-23.
SLIGHT RISK OF EXTREME HEAT FOR PORTIONS OF SOUTHERN CALIFORNIA AND THE DESERT
SOUTHWEST, THU-FRI, MAR 19-20.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF SOUTHERN CALIFORNIA, THU-SUN, MAR
19-22.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE PACIFIC NORTHWEST, NORTHERN
INTERMOUNTAIN, AND NORTHERN ROCKIES, THU-SAT, MAR 19-21.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES OVER MUCH OF SOUTHERN AND WESTERN
MAINLAND ALASKA AND PARTS OF THE SOUTHEAST, THU-WED, MAR 19-25.
SLIGHT RISK OF HIGH WINDS OVER THE SOUTHERN COAST OF ALASKA AND SOUTHEAST
ALASKA, THU-WED, MAR 19-25.
DETAILED SUMMARY
FOR SATURDAY MARCH 14 - WEDNESDAY MARCH 18:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY MARCH 19 - WEDNESDAY MARCH 25: TOWARDS THE MIDDLE OF NEXT WEEK,
BOTH THE LATEST 0Z GEFS AND ECMWF ENSEMBLES FEATURE A HIGHLY AMPLIFIED RIDGE
CENTERED OVER THE INTERIOR WEST, WITH A WEAKENING 500-HPA TROUGH DOWNSTREAM
OVER THE EASTERN U.S. SINCE YESTERDAY, THE GEFS HAS BECOME MORE AMPLIFIED WITH
THE WESTERN RIDGE, AND THE ECMWF REMAINING STRONGER, CONTINUING TO FAVOR >591
DAM HEIGHTS PEAKING OVER THE SOUTHWESTERN U.S TRANSLATING TO 3 STANDARD
DEVIATIONS ABOVE CLIMATOLOGY EXTENDING INTO THE FOUR CORNERS REGION EARLY IN
THE PERIOD. THERE CONTINUES TO BE GOOD MODEL AGREEMENT IN THE EVOLUTION OF THIS
MID-LEVEL FEATURE GRADUALLY SLIDING EASTWARD INTO THE CENTRAL HIGH PLAINS. A
LARGER COVERAGE OF POSITIVE HEIGHT DEPARTURES IS FAVORED TO OVERSPREAD THE
MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS TO SUPPORT AN EASTWARD EXPANSION OF
ABOVE-NORMAL TEMPERATURES LATER IN WEEK-2. HOWEVER, AS THIS MID-LEVEL FEATURE
DEAMPLIFIES, ONE NOVEL DEVELOPMENT FEATURED IN THE LATEST ENSEMBLE GUIDANCE IS
MORE OF A FLATTENING OF THE 500-HPA RIDGE, WITH DECREASING HEIGHTS ENCROACHING
FROM SOUTHERN CANADA. SUCH A TRANSITION WOULD FAVOR COOLER TEMPERATURES THE
NORTHERN TIER OF THE CONUS, AS WELL AS THE POTENTIAL FOR THE RETURN OF ENHANCED
ONSHORE FLOW OVER THE PACIFIC NORTHWEST IN CONJUNCTION WITH A MEAN 500-HPA
TROUGH DIGGING SOUTHWARD FROM THE GULF OF ALASKA.
UNDERNEATH THE AMPLIFIED RIDGE CENTER OVER THE INTERIOR WEST, THERE IS AN
UPTICK IN WARM SIGNALS IN PERCENTILE SPACE IN BOTH THE GEFS AND ECMWF
PROBABILISTIC EXTREME TOOLS (PETS) COMPARED TO YESTERDAY. THE GEFS REMAINS
COMPARATIVELY WEAKER THAN THE ECMWF, BUT THESE TOOLS INDICATE AT LEAST 40-50%
CHANCES FOR MAXIMUM DAYTIME TEMPERATURES EXCEEDING THE 98TH PERCENTILE FOCUSED
OVER EASTERN FOUR CORNERS REGION. ADDITIONALLY, THE NATIONAL BLEND OF MODELS
(NBM) CONTINUES TO SHOW A HIGHER NUMBER OF LOCATIONS NEARING RECORD BREAKING
DAYTIME TEMPERATURES ACROSS THE NORTHERN INTERMOUNTAIN, ROCKIES, GREAT BASIN,
CALIFORNIA AND THE DESERT SOUTHWEST EARLY IN WEEK-2. IN CONSIDERATION OF THESE
FACTORS, AS WELL AS BETTER SUPPORT IN THE CANADIAN ENSEMBLE FAVORING STRONGER
MEAN RIDGING OVER THE WEST SINCE YESTERDAY, A MODERATE RISK OF MUCH
ABOVE-NORMAL TEMPERATURES IS ISSUED FOR MAR 19-20 BEFORE THE RIDGING ALOFT
BEGINS TO DEAMPLIFY. A BROADER SLIGHT RISK AREA REMAINS POSTED FOR MUCH OF THE
WESTERN CONUS, VALID THROUGH MAR 23, WHERE PETS MAINTAIN AT LEAST A 20% CHANCE
FOR MAXIMUM TEMPERATURES EXCEEDING THE 95TH CLIMATOLOGICAL PERCENTILE. ACROSS
THE SONORAN DESERT, THE NBM FORECASTS HAVE ALSO TRENDED SLIGHTLY HIGHER IN THE
DAYTIME TEMPERATURES, NOW NEARING 105 DEG F, WHICH IS ALSO SUPPORTED IN THE
UNCALIBRATED ECMWF ENSEMBLE WITH 10-30% CHANCES FOR EXCEEDING THIS THRESHOLD
FOR SPRINGTIME HEAT. THE NWS HEAT RISK TOOL ALSO DEPICTS INCREASING ORANGE
(MODERATE) LEVEL VALUES DEVELOPING ACROSS THIS REGION AND ACROSS SOUTHERN
CALIFORNIA LATE IN WEEK-1, WHERE THE POTENTIAL FOR HIGHER MAXIMUM TEMPERATURES
HEADING INTO WEEK-2 COULD LEAD TO HEAT DRIVEN ILLNESSES FOR VULNERABLE
POPULATIONS AS WELL AS OTHER HEAT RELATED IMPACTS. THEREFORE, A SLIGHT RISK OF
EXTREME HEAT IS INTRODUCED IN THE UPDATED OUTLOOK FOR PORTIONS OF SOUTHERN
CALIFORNIA AND SOUTHWESTERN ARIZONA, VALID FOR MAR 19-20. WHILE ACTUAL
TEMPERATURES FORECAST FOR OTHER AREAS OF THE WEST (70 TO 80 DEG F) ARE NOT IN
THEMSELVES HAZARDOUS, THE UNSEASONABLE WARMTH LOOKS TO CONTRIBUTE TO AN EARLY
ONSET OF SPRING SNOWMELT WHERE HIGH ELEVATION SNOWPACK HAS ALREADY BEEN WELL
BELOW NORMAL ACROSS THE WEST. SNOWMELT IS EXPECTED TO SIGNIFICANTLY INCREASE
THIS WEEK AND LEAD TO INCREASED FLOWS. COMBINED WITH ELEVATED CHANCES FOR
BELOW-NORMAL PRECIPITATION, ANY PERSISTENCE OF THIS LEVEL OF WARMTH OVER THE
INTERIOR WEST LATER IN MARCH MAY HAVE LONGER-TERM IMPLICATIONS IN TERMS OF
DECLINING SOIL MOISTURE AND DROUGHT DEVELOPMENT.
ACCOMPANYING THE WARMTH THROUGHOUT THE WEST, STRONG MID-LEVEL RIDGING CENTERED
OVER THE GREAT BASIN ALSO SUPPORTS AN INCREASED RISK OF OFFSHORE FLOW AND SANTA
ANA WINDS FOR PORTIONS OF SOUTHERN CALIFORNIA. ENSEMBLES CONTINUE TO GROW
STRONGER WITH THE DEVELOPMENT OF SURFACE HIGH PRESSURE OVER THE FOUR CORNERS
AND GREAT BASIN, WITH BETTER INDICATIONS FOR THE DEVELOPMENT OF THERMALLY
INDUCED LOW PRESSURE IN THE SONORAN DESERT TO SUPPORT THIS FLOW SETUP.
THEREFORE, A SLIGHT RISK OF HIGH WINDS REMAINS POSTED FOR SOUTHERN CALIFORNIA,
AND IS EXTENDED THROUGH MAR 22 BEFORE THE SURFACE HIGH PRESSURE OVER THE WEST
BEGINS TO RELAX.
DUE TO A MORE EXPANSIVE COVERAGE OF POSITIVE MID-LEVEL HEIGHT DEPARTURES
EXTENDING INTO SOUTHWESTERN CANADA EARLY IN WEEK-2, ANY ENHANCED ONSHORE IS
EXPECTED TO BE DISPLACED TO THE NORTH WITH DRIER CONDITIONS PREVAILING ACROSS
MUCH OF THE NORTHWESTERN CONUS IN PROXIMITY TO THE RIDGE FURTHER SOUTH.
ALTHOUGH PARTS OF NORTHWESTERN WASHINGTON MAY RECEIVE ABOVE-NORMAL
PRECIPITATION DURING THE PERIOD, BOTH RAW AND CALIBRATED PRECIPITATION TOOLS
HAVE BECOME LESS SUPPORTIVE OF THE HEAVY PRECIPITATION POTENTIAL (<20% CHANCES
FOR AMOUNTS EXCEEDING 2 INCHES) SINCE YESTERDAY, AND A CORRESPONDING SLIGHT
RISK AREA IS REMOVED OVER WESTERN WASHINGTON IN THE UPDATED OUTLOOK. HOWEVER,
BASED ON THE PETS MAINTAINING AT LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING
THE 85TH PERCENTILE, A SLIGHT RISK OF HIGH WINDS IS POSTED (MAR 19-22) OVER
PORTIONS OF WASHINGTON, OREGON, IDAHO, AND MONTANA AS THESE AREAS MAY
EXPERIENCE EPISODES OF ELEVATED WIND SPEEDS ASSOCIATED WITH THE ENHANCED
ONSHORE FLOW REGIME TO THE NORTH. TIED TO THE EASTWARD PROGRESSION OF THE
STRONG MID-LEVEL RIDGING TO ALLOW FOR THE TROUGHING UPSTREAM TO DIG FURTHER
SOUTH OVER THE NORTHEASTERN PACIFIC, INCREASED PRECIPITATION IS FAVORED OVER
PARTS OF WESTERN OREGON AND NORTHERN CALIFORNIA BY MID WEEK-2, HOWEVER AMOUNTS
REMAIN UNSUPPORTIVE OF ANY CORRESPONDING HAZARDS AT THIS TIME.
WITH THE DOWNSTREAM TROUGHING FAVORED TO DEAMPLIFY, AND SURFACE HIGH PRESSURE
SHIFTING FARTHER EASTWARD INTO THE ATLANTIC TO INDUCE MORE RETURN FLOW FROM THE
GULF, A MODERATION OF TEMPERATURES IS EXPECTED TO BE UNDERWAY OVER THE EASTERN
U.S. HEADING INTO WEEK-2. THIS IS REFLECTED IN THE RAW TEMPERATURE TOOLS
SHOWING THE STRONGEST NEGATIVE TEMPERATURE ANOMALIES TIMING OFF INTO WEEK-1 AS
WELL AS THE PETS WHERE THERE IS REDUCED CHANCES FOR MINIMUM TEMPERATURES
FALLING BELOW FREEZING OVER THE SOUTHEAST. AS A RESULT, THE SLIGHT RISK OF
MUCH BELOW NORMAL TEMPERATURES IS REMOVED IN THE UPDATED OUTLOOK, BUT IT IS
WORTH NOTING THAT ANY RESIDUAL COLD LOOKS TO BE MORE LOCALLY CONFINED TO THE
CAROLINAS, WHERE ANY LINGERING FROST OR FREEZES MAY IMPACT EMERGING SPRING
VEGETATION TOWARDS THE MIDDLE OF NEXT WEEK.
OVER ALASKA, ANOMALOUS 500-HPA RIDGING WEST OF THE BERING STRAIT WITH
DOWNSTREAM TROUGHING OVER THE MAINLAND AND GULF OF ALASKA IS FAVORED TO BRING
WELL BELOW-NORMAL TEMPERATURES FOR THE STATE. ENSEMBLES CONTINUE TO SHOW A
GRADUAL BREAKDOWN OF THE MID-LEVEL TROUGHING OVER THE STATE, HOWEVER PETS
INDICATE ELEVATED CHANCES FOR MINIMUM TEMPERATURES FALLING BELOW THE 15TH
PERCENTILE THROUGHOUT THE ENTIRETY OF WEEK-2 ASSOCIATED WITH THE PREVAILING
NORTHERLY FLOW. THEREFORE, A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES IS
MAINTAINED FOR MUCH OF ALASKA, AND NOW VALID THROUGH MAR 25. THE MID-LEVEL
TROUGHING FAVORED OVER THE NORTHEASTERN PACIFIC ALSO SUPPORTS THE CONTINUATION
OF A SLIGHT RISK OF HIGH WINDS, ALSO VALID THROUGH MAR 23. WITHIN THE
HIGHLIGHTED WIND RISK AREA, FREEZING SEA SPRAY REMAINS A CONCERN DUE TO THE
COLDER TEMPERATURES FAVORED DURING THE PERIOD.
FOLLOWING A KONA LOW EVENT ONGOING OVER THE CENTRAL PACIFIC THAT LOOKS TO BRING
HEAVY RAINS, HIGH WINDS AND FLOODING FOR HAWAII THIS WEEK, ENSEMBLES FAVOR THE
POTENTIAL FOR A RELOADING MID-LEVEL TROUGH TO THE WEST OF THE STATE NEXT WEEK,
WHICH MAY INDUCE ADDITIONAL KONA LOW DEVELOPMENT. PETS CONTINUE TO HIGHLIGHT AT
LEAST 20% CHANCES FOR 3-DAY PRECIPITATION AMOUNTS EXCEEDING THE 85TH PERCENTILE
AND 1 INCH OVER MUCH OF THE ISLAND CHAIN DURING WEEK-2. GIVEN LITTLE TO NO
RELIEF FROM THE PERSISTENTLY WET PATTERN, ANY ADDITIONAL RAINFALL IS
ANTICIPATED TO FURTHER SATURATE GROUNDS.
FORECASTER: NICK NOVELLA
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