070
FXUS21 KWNC 121923
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MARCH 12 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
CONTIGUOUS U.S. (CONUS) NEXT WEEK. SPRING EXTREME HEAT CONDITIONS ARE POSSIBLE
OVER PARTS OF THE 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 ELEVATED WIND SPEEDS UNDERNEATH AN ENHANCED ONSHORE FLOW REGIME TO THE NORTH
OVER SOUTHWESTERN CANADA. PERSISTENT MID-LEVEL HIGH PRESSURE OVER THE WESTERN
BERING SEA/EASTERN SIBERIA REMAINS FAVORED TO USHER IN BELOW-NORMAL AND
POTENTIALLY IMPACTFUL TEMPERATURES, WITH THIS HAZARD GRADUALLY EASING FOR MUCH
OF ALASKA LATER IN WEEK-2.
HAZARDS
MODERATE RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE GREAT
BASIN, CALIFORNIA, DESERT SOUTHWEST, ROCKIES, AND SOUTHERN HIGH PLAINS,
FRI-SAT, MAR 20-21.
SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FROM MUCH OF THE WESTERN CONUS
INTO THE CENTRAL AND SOUTHERN PLAINS, FRI-MON, MAR 20-23.
SLIGHT RISK OF EXTREME HEAT FOR PORTIONS OF SOUTHERN CALIFORNIA AND THE DESERT
SOUTHWEST, FRI-SAT, MAR 20-21.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF SOUTHERN CALIFORNIA, FRI-MON, MAR
20-23.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE PACIFIC NORTHWEST, NORTHERN
INTERMOUNTAIN, AND NORTHERN ROCKIES, FRI-SUN, MAR 20-22.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES OVER MUCH OF SOUTHERN AND WESTERN
ALASKA, FRI-WED, MAR 20-25.
SLIGHT RISK OF HIGH WINDS OVER THE SOUTHERN COAST OF ALASKA AND SOUTHEAST
ALASKA, FRI-WED, MAR 20-25.
DETAILED SUMMARY
FOR SUNDAY MARCH 15 - THURSDAY MARCH 19:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY MARCH 20 - THURSDAY MARCH 26: THE LATEST 0Z GEFS, ECENS, AND CMCE
MODELS FEATURE A HIGHLY AMPLIFIED RIDGE CENTERED OVER THE INTERIOR WEST, WITH A
WEAKENING 500-HPA TROUGH DOWNSTREAM OVER THE EASTERN CONUS. ACCORDING TO THESE
ENSEMBLES, THE PEAK HEIGHTS ARE PREDICTED ON DAY 7 (MAR 19), WITH A VERY
GRADUAL DECLINE IN HEIGHTS THEREAFTER. THE ECENS REMAINS SLIGHTLY STRONGER,
INDICATING 593 DM HEIGHTS ON MAR 19, DROPPING TO 591 DM AT THE START OF WEEK-2.
THE PEAK HEIGHTS TRANSLATE 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 AND SOUTHERN HIGH PLAINS. SUBSEQUENTLY, HEIGHTS ARE
FORECAST TO RISE ACROSS THE CENTRAL AND SOUTHEASTERN CONUS IN WEEK-2,
ACCOMPANIED BY INCREASING COVERAGE OF ABOVE-NORMAL TEMPERATURES. HOWEVER,
HEIGHTS ARE FORECAST TO FALL ACROSS THE PACIFIC NORTHWEST IN CONJUNCTION WITH A
MEAN 500-HPA TROUGH DIGGING SOUTHWARD FROM THE GULF OF ALASKA. THIS MAY RESULT
IN A RETURN TO INCREASED ONSHORE FLOW OVER THE PACIFIC NORTHWEST.
UNDERNEATH THE AMPLIFIED RIDGE CENTER OVER THE INTERIOR WEST, THE WARM SIGNALS
IN PERCENTILE SPACE IN BOTH THE GEFS AND ECMWF PROBABILISTIC EXTREME TOOLS
(PETS) REMAIN QUITE STRONG AT THE VERY START OF WEEK-2. THE GEFS REMAINS
COMPARATIVELY WEAKER THAN THE ECMWF, BUT THESE TOOLS INDICATE AT LEAST 60-80%
CHANCES FOR MAXIMUM DAYTIME TEMPERATURES EXCEEDING THE 98TH PERCENTILE FOCUSED
OVER THE EASTERN FOUR CORNERS REGION. ADDITIONALLY, THE NATIONAL BLEND OF
MODELS (NBM) CONTINUES TO SHOW A HIGH NUMBER OF LOCATIONS (51) NEARING RECORD
BREAKING DAYTIME TEMPERATURES ACROSS THE NORTHERN INTERMOUNTAIN REGION,
ROCKIES, GREAT BASIN, CALIFORNIA AND THE DESERT SOUTHWEST EARLY IN WEEK-2. IN
CONSIDERATION OF THESE FACTORS, A MODERATE RISK OF MUCH ABOVE-NORMAL
TEMPERATURES IS ISSUED FOR MAR 20-21 BEFORE THE RIDGING ALOFT BEGINS TO
DEAMPLIFY. A BROADER SLIGHT RISK AREA REMAINS POSTED FOR MUCH OF THE WESTERN
CONUS CONTINUING INTO THE CENTRAL AND SOUTHERN PLAINS, VALID THROUGH MAR 23,
WHERE PETS MAINTAIN AT LEAST A 20% CHANCE FOR MAXIMUM TEMPERATURES EXCEEDING
THE 90TH CLIMATOLOGICAL PERCENTILE. ACROSS THE SONORAN DESERT, THE NBM
FORECASTS HAVE ALSO TRENDED SLIGHTLY HIGHER IN THE DAYTIME TEMPERATURES, NOW
SLIGHTLY EXCEEDING 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,
WHICH COULD LEAD TO HEAT DRIVEN ILLNESSES FOR VULNERABLE POPULATIONS AS WELL AS
OTHER HEAT RELATED IMPACTS. THEREFORE, A SLIGHT RISK OF EXTREME HEAT CONTINUES
IN THE UPDATED OUTLOOK FOR PORTIONS OF SOUTHERN CALIFORNIA AND SOUTHWESTERN
ARIZONA, VALID FOR MAR 20-21. 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 FAVOR 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
23 BEFORE THE SURFACE HIGH PRESSURE OVER THE WEST BEGINS TO RELAX.
DUE TO MORE EXPANSIVE COVERAGE OF POSITIVE MID-LEVEL HEIGHT DEPARTURES
EXTENDING INTO SOUTHWESTERN CANADA EARLY IN WEEK-2, ANY ENHANCED ONSHORE FLOW
IS EXPECTED TO BE DISPLACED TO THE NORTH WITH DRIER CONDITIONS PREVAILING
ACROSS MUCH OF THE NORTHWESTERN CONUS IN PROXIMITY TO THE RIDGE FARTHER SOUTH.
THE PETS CONTINUE TO PREDICT SUBHAZARDOUS PRECIPITATION AMOUNTS OVER THE
PACIFIC NORTHWEST (<20% CHANCE OF 2 INCHES OR GREATER); IN FACT, PREDICTED
AMOUNTS ARE CLOSER TO 1-INCH. 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 20-22) 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 FARTHER 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
LOWER 48 STATES 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 ARE REDUCED CHANCES FOR MINIMUM
TEMPERATURES FALLING BELOW FREEZING OVER THE SOUTHEAST. 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 OVER THE WESTERN BERING SEA/EASTERN
SIBERIA WITH DOWNSTREAM TROUGHING OVER THE MAINLAND AND GULF OF ALASKA IS
FAVORED TO BRING WELL BELOW-NORMAL TEMPERATURES TO THE STATE. ENSEMBLES
CONTINUE TO SHOW A GRADUAL BREAKDOWN OF THE MID-LEVEL TROUGHING OVER THE STATE
LATER IN WEEK-2, 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 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 25. 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 TO 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. THE ECENS PET CONTINUES TO
HIGHLIGHT AT LEAST 20% CHANCES FOR 3-DAY PRECIPITATION AMOUNTS EXCEEDING THE
85TH PERCENTILE AND 1.5 INCHES OVER MUCH OF THE ISLAND CHAIN DURING WEEK-2,
WHEREAS THE GEFS IS CLOSER TO 0.75-INCH. GIVEN LITTLE TO NO RELIEF FROM THE
PERSISTENTLY WET PATTERN, ANY ADDITIONAL RAINFALL IS ANTICIPATED TO FURTHER
SATURATE GROUNDS.
FORECASTER: ANTHONY ARTUSA
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