…Widespread heavy rain threat from the central to eastern Gulf Coast
region, northeastward across all of the east…
…Active Lake effect snows to begin Wednesday and continue through
Thursday downwind of the Lakes…
…Record warm morning lows likely along the east coast Wednesday
morning…
…Arctic air to surge south into the Northern Plains/Upper Mississippi
Valley region late Tuesday into Wednesday…
…Critical to Extreme fire weather danger across portions of Southern
California…
The upper level flow will undergo significant amplification across much of
North America over the next few days, producing active and impactful
weather events across nearly all of the Lower 48. This amplifying pattern
will be comprised of a building upper ridge along the West coast and a
deepening upper trof across the central to eastern U.S. Precipitation
currently falling across portions of the central to eastern Gulf coast and
the Northeast will be followed a more widespread heavy precipitation event
developing Tuesday night into early Wednesday from the central Gulf coast
into the Upper Ohio Valley. This area of precipitation will continue to
expand eastward during the day Wednesday across all of the east, producing
widespread heavy precipitation from the central to eastern Gulf coast,
across the Southeast, Mid-Atlantic, Northeast and New England. With much
of these areas currently in moderate to extreme drought conditions, this
rainfall will be beneficial. Still, given the potential for periods of
heavy rains over a short period, there will be a threat of localized flash
flooding, especially in more urbanized regions.
This heavy rain will be occurring along and ahead of a strong front
pushing east across the eastern U.S. on Wednesday. Ahead of this front,
there is the potential for widespread record high morning low temperatures
on Wednesday across the Southern Mid-Atlantic, Mid-Atlantic and portions
of the Northeast. In the wake of this front, much colder temperatures
will begin to push across the Great Lakes from west to east, beginning on
Wednesday. This will ignite active lake effect snows, initially downwind
of lakes Superior and Michigan on Wednesday and then downwind of lakes
Erie and Ontario Wednesday night into early Thursday. Before these lake
effect snows diminish by early Friday, snowfall totals of 1 to 2 feet are
possible in the favored lake effect snow regions across portions of
northwest and western New York State, far northwest Pennsylvania, far
northeastern Ohio, the Upper Peninsula of Michigan and the western
portions of the Lower Peninsula of Michigan.
The above mentioned lake effect snows will be driven by arctic air that
will be first surging east southeastward late Tuesday into early Wednesday
across the Northern Plains into the Upper Mississippi Valley and then
eastward trough the Great Lakes into the Ohio Valley on Wednesday. While
there are not expected to be any records with this arctic outbreak,
temperatures will be much below average on Wednesday across the Northern
Plains into the Upper Mississippi Valley. These much below average
temperatures will then push farther southeast into the Great Lakes and
Ohio Valley region on Thursday. Across these regions, high temperatures
will be 10 to 25 degrees below average during the height of the cold
temperatures during Wednesday and Thursday.
In contrast to the wet and cold conditions across portions of the north
central to eastern U.S., dry condition and milder temperatures are in
store across the West coast, Great Basin and Rockies region. However, the
dry air, low relative humidities and windy Santa Ana conditions over
Southern California will produce critical to locally extreme fire weather
conditions. These fire weather conditions will be greatest in the higher
terrain areas to the north and east of the Los Angeles to San Diego
region. Winds of 35 to 45 mph in the valleys and gusts of 50 to 65 mph in
the mountains will help fan any fires that do develop quickly and may
reduce visibility with blowing smoke and dust adding to travel concerns in
the region. Across these areas, red flag warnings are currently in
effect, affecting nearly 13 million people.
Oravec
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php