916
FXUS21 KWNC 211922
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MARCH 21 2024
SYNOPSIS: AS WEEK-2 STARTS, SURFACE LOW PRESSURE IS FAVORED TO TRACK
NORTHEASTWARD FROM NEAR THE SOUTHEAST COAST, SUSTAINING AN INCREASED RISK OF
HEAVY PRECIPITATION AND EPISODES OF HIGH WINDS FOR MUCH OF THE EASTERN
SEABOARD. DYNAMICAL MODELS CONTINUE TO SHOW MID-LEVEL LOW PRESSURE ENCROACHING
THE WEST COAST, ELEVATING THE RISK OF HEAVY RAIN AND SNOW, AND HIGH WINDS FOR
PARTS OF CALIFORNIA AND THE PACIFIC NORTHWEST. AS THIS MID-LEVEL LOW PRESSURE
SHIFTS INLAND, ADDITIONAL SURFACE LOW FORMATION IS FAVORED IN THE LEE OF THE
ROCKIES, BRINGING A RENEWED RISK FOR HEAVY PRECIPITATION ACROSS THE
SOUTHEASTERN CONTIGUOUS U.S. (CONUS), HEAVY SNOW FROM THE ROCKIES TO THE
WESTERN GREAT LAKES, AND PERIODS OF HIGH WINDS ACROSS A BROAD AREA FROM THE
ROCKIES AND GREAT PLAINS TO THE EAST COAST LATER IN WEEK-2.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION OVER MUCH OF THE EASTERN SEABOARD, FRI, MAR
29.
SLIGHT RISK OF PERIODS OF HIGH WINDS FOR MUCH OF THE ROCKIES, GREAT PLAINS, AND
EASTERN CONUS, FRI-WED, MAR 29-APR 3.
SLIGHT RISK OF HEAVY PRECIPITATION OVER MUCH OF CALIFORNIA AND ADJACENT OREGON,
FRI-SAT, MAR 29-30.
SLIGHT RISK OF HEAVY SNOW OVER THE HIGHER ELEVATIONS OF THE SIERRA NEVADA AND
SOUTHERN CASCADES, FRI-SAT, MAR 29-30.
SLIGHT RISK OF HIGH WINDS ALONG MUCH OF THE WEST COAST, FRI-SAT, MAR 29-30.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE MISSISSIPPI, TENNESSEE, AND
OHIO VALLEYS, AND THE SOUTHEAST, MON-WED, APR 1-3.
SLIGHT RISK OF HEAVY SNOW OVER PORTIONS OF THE ROCKIES, NORTHERN AND CENTRAL
PLAINS, UPPER MISSISSIPPI VALLEY, AND GREAT LAKES, FRI-TUE, MAR 29-APR 2.
DETAILED SUMMARY
FOR SUNDAY MARCH 24 - THURSDAY MARCH 28:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY MARCH 29 - THURSDAY APRIL 04: MULTIPLE DYNAMICAL MODELS CONTINUE TO
ADVERTISE PREDOMINATELY BELOW NORMAL 500-HPA HEIGHTS OVERSPREADING MUCH OF THE
CONUS, WHILE KEEPING MUCH OF THE ANOMALOUS MID-LEVEL RIDGING CONFINED TO THE
HIGHER LATITUDES OF NORTH AMERICA IN THE MEAN WEEK-2 HEIGHT FIELDS. THE HEIGHT
PATTERN OVER THE CONUS IS ANTICIPATED TO REMAIN PROGRESSIVE, CONSISTING OF A
SERIES OF SHORTWAVE DISTURBANCES PROPAGATING EASTWARD, MAINTAINING AN INCREASED
RISK OF PERIODS OF POTENTIALLY IMPACTFUL WEATHER THROUGHOUT THE PERIOD.
MULTIPLE MODEL TOOLS CONTINUE TO SUGGEST THAT WEEK-2 WILL FEATURE A VERY
PROGRESSIVE PATTERN ACROSS THE CONUS, WITH MID-LEVEL TROUGHS AND ASSOCIATED
SURFACE STORM SYSTEMS TRAVERSING WEST-TO-EAST ACROSS THE CONUS. THE EUROPEAN
ENSEMBLE MEAN REMAINS MORE AMPLIFIED AND SLIGHTLY SLOWER THAN THE GEFS. THE
CANADIAN ENSEMBLE MEAN BETTER RESEMBLES THE GEFS IN THE EASTERN CONUS EARLY IN
THE PERIOD, BUT LEANS TOWARD THE MORE AMPLIFIED EUROPEAN ENSEMBLE MEAN WITH THE
NEXT UPSTREAM SYSTEM THAT BEGINS WEEK-2 JUST OFF THE WEST COAST.
WEEK-2 STARTS WITH A STRONG STORM SYSTEM OVER OR NEAR THE SOUTHEAST COAST,
TRACKING QUICKLY NORTHEASTWARD OR EAST-NORTHEASTWARD INTO THE WESTERN ATLANTIC.
THERE IS MULTI-MODEL DEPICTION OF A FAIRLY STRONG STORM SYSTEM NEAR THE
SOUTHEAST COAST THAT INTENSIFIES AS IT MOVES AWAY. THE 12Z OPERATIONAL GFS THEN
PUSHES THIS SYSTEM QUICKLY OUT TO SEA WHILE THE EUROPEAN AND CANADIAN
OPERATIONAL MODELS KEEP THE SYSTEM STRONGER AND CLOSER TO THE COAST, WITH THE
CANADIAN BRINGING STORMY CONDITIONS FARTHER NORTH ALONG THE EAST COAST THAN THE
EUROPEAN. THIS REPRESENTS AN EASTWARD SHIFT FROM YESTERDAY IN ALL THREE MODELS.
THE PROBABILISTIC EXTREMES TOOLS ARE ALL UNIMPRESSIVE, SHOWING VERY SLIGHTLY
ELEVATED ODDS FOR HAZARDOUS CONDITIONS. ALTHOUGH THE GUIDANCE IS INCONSISTENT,
SLIGHT RISKS OF HEAVY PRECIPITATION AND HIGH WINDS ARE MAINTAINED IN THE
MID-ATLANTIC AND NORTHEAST, BUT THE RISKS ARE CONFINED CLOSER TO THE COAST THAN
YESTERDAY, CONSISTENT WITH THE DETERMINISTIC MODELS.
FARTHER WEST, MODELS HAVE BEEN CONSISTENT WITH ANOTHER 500-HPA TROUGH UPSTREAM
APPROACHING THE WEST COAST EARLY IN WEEK-2. THE ENHANCED ONSHORE FLOW IS
EXPECTED TO CONTINUE AN INCREASED RISK OF HEAVY PRECIPITATION (PRIMARILY SNOW
IN THE HIGHER ELEVATIONS) AND HIGH WINDS BEFORE THE MID-LEVEL SYSTEM MOVES
INLAND. CORRESPONDING SLIGHT RISK AREAS FOR HEAVY PRECIPITATION, HIGH ELEVATION
HEAVY SNOW, AND HIGH WINDS REMAIN POSTED OVER PARTS OF CALIFORNIA AND THE
PACIFIC NORTHWEST VALID THROUGH MAR 30. SOME DYNAMICAL MODELS AND A FEW MEMBERS
OF THE ENSEMBLES IMPLY A MODERATE RISK FOR HEAVY SNOW, WITH LIQUID-EQUIVALENT
PRECIPITATION TOTALLING 1 TO 2 INCHES DURING A 2-DAY PERIOD. HOWEVER, SOME OF
THIS INFLATION IN PERCENTILE SPACE IS DUE TO A DRYING CLIMATOLOGY DURING LATE
MARCH, AND WITH SOME MODEL OUTPUT FORECASTING LESS PRECIPITATION, ONLY SLIGHT
RISKS FOR HEAVY PRECIPITATION AND HEAVY SNOW ARE POSTED.
A DISSIPATING MID-LEVEL TROUGH IN THE CENTRAL CONUS WILL BE MOVING EASTWARD,
SUPPORTING AN ASSOCIATED SURFACE LOW PRESSURE SYSTEM TRACKING FROM THE UPPER
MIDWEST THROUGH THE GREAT LAKES AND INTO EASTERN CANADA EARLY WEEK-2.
MEANWHILE, THE MID-LEVEL TROUGH NEAR THE WEST COAST IS FORECAST TO MOVE EAST
ACROSS THE INTERIOR WEST AND INTO THE CENTRAL CONUS. THIS PATTERN FAVORS LEE
CYCLOGENESIS EAST OF THE ROCKIES TOWARDS THE MIDDLE OF WEEK-2, AND A SECOND
SYSTEM TAKING A PATH SIMILAR TO THE FIRST ONE, THROUGH THE GREAT PLAINS AND
INTO THE GREAT LAKES, LATER WEEK-2. THE PRIMARY DIFFERENCE, DEMONSTRATED BY
MOST OF THE MODELS AND TOOLS, IS THAT THE LATER SYSTEM SHOULD BE CONSIDERABLY
STRONGER THAN THE ONE MOVING AWAY EARLY IN THE WEEK. WHILE THE DETAILS OF THE
STORM TRACKS ARE QUITE UNCERTAIN AT THIS LEAD, ACCUMULATING SNOWFALL IS FAVORED
ON THE BACKSIDE OF BOTH LOW PRESSURE SYSTEMS, WHERE ANOMALOUSLY COLD AIR IS
EXPECTED TO BE ESTABLISHED. THUS A SLIGHT RISK FOR HEAVY SNOW IS POSTED FOR A
BROAD AREA FROM THE CENTRAL AND NORTHERN ROCKIES EASTWARD ACROSS MUCH OF THE
PLAINS AND INTO THE UPPER MIDWEST AND WESTERN GREAT LAKES REGION MUCH OF
WEEK-2, WITH THE SECOND SYSTEM CLEARING THE REGION LATE IN THE WEEK, ENDING THE
SNOW HAZARD. THE EUROPEAN ENSEMBLES INDICATE THAT ODDS FOR GREATER THAN 6
INCHES OF SNOW EXCEED 50 PERCENT IN PART OF THE NORTH-CENTRAL PLAINS.
GIVEN THE INITIAL STORM ALONG THE EAST COAST, A SECOND STORM MOVING FROM THE
PLAINS THROUGH THE GREAT LAKES EARLY WEEK-2, AND ANOTHER STRONGER STORM TAKING
A SIMILAR TRACK LATER IN THE WEEK, A SLIGHT RISK OF EPISODIC HIGH WINDS IS
POSTED ACROSS A LARGE PART OF THE CONUS FROM THE SOUTHERN ROCKIES EASTWARD
THROUGH MUCH OF THE CENTRAL AND EASTERN CONUS. THE EXTENSIVE HIGH WIND RISK IS
POSTED FOR PERIODS OF ENHANCED WINDS DURING A BROAD PERIOD (MOST OF WEEK-2)
ASSOCIATED WITH A SERIES OF STORM SYSTEMS MOVING PROGRESSIVELY THROUGH THE
REGION, AND DOES NOT REFLECT A RISK THAT UNIVERSALLY COVERS THE ENTIRE REGION
FOR THE ENTIRE PERIOD.
MULTIPLE DYNAMICAL MODELS CONTINUE TO INDICATE SOUTHERLY WINDS ASSOCIATED WITH
THE SURFACE LOW PRESSURE MOVING THROUGH THE CENTRAL CONUS LATER WEEK-2
ADVECTING WARM, MOIST AIR FROM THE GULF OF MEXICO INTO THE SOUTHEAST AND
ADJACENT SECTIONS OF THE MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, UNDER
CYCLONICALLY CURVED FLOW ALOFT. THIS SET-UP FAVORS ENHANCED TO HEAVY
PRECIPITATION, THUS A SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED IN THIS AREA
LATER IN WEEK-2 WHILE THE MID-LEVEL TROUGH AND SURFACE STORM SYSTEM TRACK TO
THE NORTH AND WEST OF THE REGION.
STRONG 500-HPA RIDGING IS EXPECTED ACROSS MOST OF ALASKA EARLY WEEK-2, BUT
MID-LEVEL HEIGHTS SHOULD DROP AS AN ANOMALOUS MID-LEVEL ANOMALOUS TROUGH
DEVELOPS NEAR THE ALEUTIANS, APPROACHING THE SOUTHWESTERN MAINLAND LATER IN THE
PERIOD. THE ASSOCIATED SURFACE LOW PRESSURE SYSTEM SLIGHTLY DOWNSTREAM FROM THE
MID-LEVEL TROUGH FAVORS ANOMALOUSLY STRONG FLOW FROM THE NORTH PACIFIC INTO
SOUTHERN ALASKA, RESULTING IN PERIODS OF ENHANCED PRECIPITATION WINDS.
CONDITIONS, HOWEVER, ARE EXPECTED TO REMAIN BELOW HAZARDS THRESHOLDS, THUS NO
HAZARDS ARE POSTED FOR ALASKA.
FORECASTER: RICH TINKER
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