593
FXUS21 KWNC 081914
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST JANUARY 08 2024
SYNOPSIS: STRONG MID-LEVEL LOW PRESSURE SHIFTING EASTWARD WITH TIME IS EXPECTED
TO PROMOTE THE ADVECTION OF ARCTIC AIR, WHERE THERE IS AN ELEVATED RISK OF MUCH
BELOW NORMAL WINTERTIME MINIMUM TEMPERATURES FOR MANY PARTS OF THE CENTRAL AND
EASTERN CONUS DURING THE PERIOD. EARLY IN WEEK-2, ADDITIONAL LOW PRESSURE
DEVELOPMENT OVER THE EASTERN U.S. MAY LEAD TO HEAVY SNOWFALL ACCUMULATIONS FROM
THE OHIO VALLEY TO THE NORTHEAST. DESPITE DISPARITIES IN THE MODEL GUIDANCE
UPSTREAM OVER THE WEST, ENHANCED ONSHORE FLOW MAY LEAD TO HEAVY PRECIPITATION
AND HIGH ELEVATION SNOWFALL OVER THE WEST COAST AND INTERIOR WEST.
HAZARDS
HIGH RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF GREAT PLAINS,
MISSISSIPPI, TENNESSEE AND OHIO VALLEYS, TUE-WED, JAN 16-17.
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FROM GREAT PLAINS EASTWARD TO
THE SOUTHEAST AND MID-ATLANTIC, TUE-THU, JAN 16-18.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR MUCH OF THE CENTRAL AND
EASTERN CONUS, TUE-MON, JAN 16-22
SLIGHT RISK OF HIGH WINDS OVER MUCH OF EASTERN CONUS, TUE-THU, JAN 16-18.
SLIGHT RISK OF HEAVY SNOW OVER PARTS OF THE MISSISSIPPI, TENNESSEE AND OHIO
VALLEYS, MID-ATLANTIC, GREAT LAKES, APPALACHIANS, AND NORTHEAST, TUE-WED, JAN
16-17.
SLIGHT RISK OF HIGH WINDS OVER THE WEST COAST AND PARTS OF THE INTERIOR WEST,
TUE-MON, JAN 16-22.
SLIGHT RISK OF HEAVY PRECIPITATION OVER NORTHERN CALIFORNIA AND THE PACIFIC
NORTHWEST, TUE-MON, JAN 16-22.
SLIGHT RISK OF HIGH ELEVATION HEAVY SNOW OVER THE SIERRA NEVADAS, KLAMATH
MOUNTAINS, AND THE CASCADES OF THE WEST COAST, TUE-MON, JAN 16-22.
SLIGHT RISK OF HEAVY SNOW OVER THE HIGHER ELEVATIONS OF THE GREAT BASIN,
NORTHERN INTERMOUNTAIN, CENTRAL AND NORTHERN ROCKIES, TUE-MON, JAN 16-22.
POSSIBLE FLOODING FOR MOST OF THE EAST COAST STATES FROM NORTHERN FLORIDA TO
CENTRAL NEW ENGLAND.
DETAILED SUMMARY
FOR THURSDAY JANUARY 11 - MONDAY JANUARY 15:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY JANUARY 16 - MONDAY JANUARY 22: OVER THE PAST FEW DAYS, A TREND
OBSERVED AMONG THE DYNAMICAL MODELS IS A FAVORED EXPANSION OF MEAN POSITIVE
500-HPA HEIGHT DEPARTURES OVER THE SOUTHWESTERN CONUS BY NEXT WEEKEND.
ACCOMPANIED BY STRONGLY AMPLIFIED MID-LEVEL RIDGING FEATURED OVER THE HIGHER
LATITUDES OF NORTH AMERICA, WITH A MAXIMUM HEIGHT CENTER OVER GREENLAND
CONSISTENT WITH A NEGATIVE NORTH ATLANTIC OSCILLATION PATTERN (-NAO), THE
RESULTANT DOWNSTREAM TROUGHING OVER THE CENTRAL AND EASTERN CONUS IS EXPECTED
TO PROMOTE THE ADVECTION OF ARCTIC AIR WITH VERY CHILLY WINTERTIME TEMPERATURES
FAVORED FOR MANY AREAS EAST OF THE ROCKIES DURING THE PERIOD. BASED ON THE
WEATHER PREDICTION CENTERS (WPC) DAY 7 SURFACE FORECASTS, MUCH OF THE
ANOMALOUSLY COLD AIR LOOKS TO BE ESTABLISHED OVER THE GREAT PLAINS, WITH
SURFACE HIGH PRESSURE EXPANDING EASTWARD INTO THE MISSISSIPPI, TENNESSEE, AND
OHIO VALLEYS BY THE START OF WEEK-2. ON DAY 8 (JAN 16), THERE IS GOOD
AGREEMENT BETWEEN THE GEFS AND ECMWF PROBABILISTIC EXTREMES TOOLS (PETS)
DEPICTING A LARGE COVERAGE WITH AT LEAST A 40% (20%) FOR MINIMUM TEMPERATURES
FALLING BELOW 15TH (5TH) PERCENTILES IN THE WAKE OF A FRONTAL BOUNDARY. GIVEN
SUPPORT FROM THE RAW TEMPERATURE TOOLS AS WELL AS THE NATIONAL BLEND OF MODELS
(NBM) INDICATING A FEW STATIONS APPROACHING NEAR RECORD MINIMUM TEMPERATURES
EARLY NEXT WEEK, A BROAD MODERATE RISK AREA OF MUCH BELOW NORMAL TEMPERATURES
IS POSTED FROM THE GREAT PLAINS TO THE SOUTHEAST AND MID-ATLANTIC FOR JAN
16-18. A HIGH RISK OF MUCH BELOW NORMAL TEMPERATURES IS ALSO POSTED AND
CENTERED OVER THE CORN BELT WHERE PETS SHOW AT LEAST A 60% CHANCE OF MINIMUM
TEMPERATURES FALLING BELOW THE 15TH PERCENTILE AND BELOW ZERO DEGREES F DURING
THE FIRST FEW DAYS OF THE PERIOD (JAN 16-17). AS THE SURFACE HIGH SHIFTS
EASTWARD WITH TIME, THERE IS ALSO THE POTENTIAL FOR STRENGTHENING SURFACE
PRESSURE GRADIENTS WITH SURFACE LOW PRESSURE FORECAST OVER THE CANADIAN
MARITIMES. THEREFORE, A SLIGHT RISK OF HIGH WINDS IS POSTED (JAN 16-18) AT THE
BASE OF THE AMPLIFIED TROUGH ALOFT WHICH IS ALSO SUPPORTED BY THE ECMWF PET.
THE COMBINATION OF ELEVATED WIND SPEEDS WITH BELOW NORMAL WINTERTIME
TEMPERATURES ARE LIKELY TO LEAD TO VERY LOW AND POSSIBLY DANGEROUS WIND CHILLS
EARLY IN THE PERIOD. THE GEFS BASED BIAS CORRECTED WIND CHILL TOOL SHOWS
INCREASED CHANCES FOR VALUES FALLING BELOW -20 DEG F FOR MANY PARTS OF THE
MIDWEST (-40 DEG F ACROSS THE DAKOTAS AND MINNESOTA).
BEYOND DAY 10 (JAN 18), PETS AND RAW TEMPERATURE TOOLS FAVOR SOME MODERATION OF
TEMPERATURES, BUT POINT TO A SECONDARY ROUND OF COLD AIR ADVECTION LIKELY
ASSOCIATED WITH ANOTHER SHORTWAVE DISTURBANCE TO REINFORCE THE ANOMALOUSLY COLD
AIR TOWARDS THE MIDDLE OF WEEK-2. THIS IS REFLECTED IN THE PETS WHICH DEPICT
SOME REEMERGENCE OF THE COLD SIGNALS, THOUGH CHANCES OF REACHING HAZARD
CRITERIA ARE GENERALLY LOWER COMPARED TO EARLIER IN WEEK-2. TO ADDRESS
UNCERTAINTY AT THIS LEAD, A BROAD SLIGHT RISK AREA OF MUCH BELOW NORMAL
TEMPERATURES IS ISSUED FOR THE ENTIRETY OF WEEK-2 AND THE RENEWED POTENTIAL FOR
HAZARDOUS COLD WILL CONTINUE TO BE MONITORED IN SUBSEQUENT OUTLOOKS.
PRIOR TO THE ARRIVAL OF THE ARCTIC AIR MASS FAVORED OVER THE EASTERN CONUS,
GOOD CONTINUITY EXISTS IN THE GFS AND ECMWF DETERMINISTIC SOLUTIONS WHICH
FEATURE A FAST-MOVING SHORTWAVE DISTURBANCE AND ANOTHER DEEPENING LOW PRESSURE
SYSTEM POSSIBLY IMPACTING THE EASTERN U.S EARLY IN THE PERIOD. WHILE THE
HEAVIEST PRECIPITATION AMOUNTS ARE FAVORED OFFSHORE BASED ON RAW AND CALIBRATED
PET GUIDANCE TO PRECLUDE A CORRESPONDING HEAVY PRECIPITATION RISK, RESIDUAL
MOISTURE ON THE BACKSIDE OF THE DEPARTING LOW IS LIKELY TO PRODUCE ACCUMULATING
AND POSSIBLY HEAVY SNOWFALL OVER PARTS OF THE EASTERN U.S. BOTH THE GEFS BASED
SNOW WATER EQUIVALENT (SWE) PET AND THE RAW ECMWF SUPPORT THIS POTENTIAL, AND A
SLIGHT RISK OF HEAVY SNOW IS ISSUED OVER MANY PARTS OF THE NORTHEASTERN CONUS
(JAN 16-17). MIXED PRECIPITATION TYPES ARE POSSIBLE ALONG THE SOUTHERN
PERIPHERY OF THE HIGHLIGHTED SLIGHT RISK AREA. DUE TO THE SHORT RETURN
INTERVAL OF STORM SYSTEMS FORECAST TO BRING ABOVE-NORMAL PRECIPITATION DURING
WEEK-1 AND LINGERING INTO EARLY WEEK-2, A FLOODING POSSIBLE HAZARD REMAINS
ISSUED FOR MOST OF THE ATLANTIC COAST STATES FROM NORTHERN FLORIDA TO CENTRAL
NEW ENGLAND. MANY AREAS IN THE HIGHLIGHTED AREA HAVE REGISTERED PRECIPITATION
SURPLUSES IN EXCESS OF 4-5 INCHES, AS ANY ADDITIONAL PRECIPITATION, AND/OR
RAINFALL ON ANTECEDENT SNOWPACK IS LIKELY TO WORSEN SATURATED GROUND
CONDITIONS. AS THE ANOMALOUSLY COLD AIR OVERSPREADS THE EASTERN CONUS,
INCREASINGLY DRIER CONDITIONS ARE ANTICIPATED FOR MUCH OF THE EASTERN CONUS
WHICH SHOULD SERVE AS A WELCOMED BREAK FROM THE PERSISTENTLY ENHANCED
PRECIPITATION FAVORED THROUGH THE MIDDLE OF JANUARY.
UPSTREAM, DESPITE THE MORE ANOMALOUS RIDGING GENERALLY FAVORED OVER THE WESTERN
CONUS COMPARED TO EARLIER ENSEMBLE MEAN GUIDANCE, BOTH THE GEFS AND ECMWF
FEATURE THE POTENTIAL FOR INTERMITTENT ROUNDS OF SHORTWAVE ENERGY ALLOWING FOR
PERIODS OF ENHANCED ONSHORE FLOW OVER PARTS OF THE WEST COAST. THE ECMWF IS
CONSIDERABLY MORE BULLISH WITH THIS POTENTIAL THAN THE GEFS DUE TO MORE
TROUGHING FEATURED ALOFT, WHICH IS REFLECTED IN BOTH THE INTEGRATED VAPOR
TRANSPORT (IVT) TOOLS AND THE PETS THROUGH THE MIDDLE OF WEEK-2. AS BOTH PETS
GENERALLY SHOW INCREASED CHANCES FOR 3-DAY PRECIPITATION AMOUNTS EXCEEDING THE
85TH PERCENTILE, A SLIGHT RISK OF HEAVY PRECIPITATION AND A CORRESPONDING
SLIGHT RISK OF HIGH ELEVATION HEAVY SNOW ARE ISSUED FROM NORTHERN CALIFORNIA TO
THE PACIFIC NORTHWEST FOR THE ENTIRETY OF WEEK-2. MODEST SIGNALS FOR
ATMOSPHERIC RIVER ACTIVITY ALSO SUPPORT A SLIGHT RISK OF HIGH WINDS FOR THE
WEST COAST AND PARTS OF THE INTERIOR WEST FOR WEEK-2. GIVEN SUPPORT FOR
ENHANCED TROPOSPHERIC MOISTURE SPREADING EASTWARD INTO THE INTERIOR WEST, A
SLIGHT RISK OF HIGH ELEVATION HEAVY SNOW IS POSTED FOR PARTS OF THE GREAT
BASIN, NORTHERN INTERMOUNTAIN, AND THE ROCKIES FOR JAN 16-22.
OVER ALASKA, ANOMALOUS MID-LEVEL RIDGING CENTERED OVER THE ALEUTIANS IS
EXPECTED TO PRODUCE INCREASED ONSHORE FLOW AND TILT TOWARDS ABOVE-NORMAL
PRECIPITATION FOR MANY PARTS OF THE MAINLAND AND SOUTHEAST. NO PRECIPITATION OR
WIND RELATED HAZARDS ARE ISSUED DUE TO THE LACK OF SUPPORT IN THE PET GUIDANCE.
FORECASTER: NICK NOVELLA
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