It is looking more and more of a possibility for some frozen
precipitation for the Tuesday morning. A cold trough is beginning to descend
over the middle of the country bringing frigid temperatures once again for a
majority of the nation’s mid-section. With that trough brings a tremendous
amount of energy that will cool off the temperatures dramatically Monday into
Tuesday.
Things will begin as rain Monday afternoon, but as the evening hours
roll along, a large blast of cold air will leave
temperatures hanging right near the freezing mark by the surface. With
sufficient depth in the cold air in the upper levels, it almost does not matter
the temperature directly at the surface. As long as the temperature stays near or below
the freezing mark, the possibility for sleet or freezing rain is highly likely
in the morning hours.
What will continue to be monitored is how the different
ingredients of a frozen precipitation scenario line up. For example, most of
the cold air will be due to a “blocking” high up north which will help pull
cold air into the region while the moisture comes in from the southwest. Another
factor is timing, whether the heaviest of the predicted precipitation is of the
frozen variety (freezing rain, sleet or mix) or it is rain can have a
tremendous impact on road conditions for Tuesday. Finally, and most importantly the vertical profile of temperature for this particular case can have a dramatic impact on what will fall from sky: rain, sleet, freezing rain, snow or a mix.
The forecast now seems to
point for mostly rain with the best chance of mix from 7am-10am, but this again could change.
Rather than give a
definitive forecast, we will just run through a timeline starting with tonight.
Sunday Evening/Night: Mostly clear skies, winds from the SSW
with temperatures staying fairly mild. Low tonight of only 47.
Monday Morning/Midday: Cloudy skies will develop, though the
temperature again will be mild for this time of year. High near 60. Winds will
shift from out of the West to out of the Northwest (front starting to come
through)
Monday Afternoon/Evening: Temperatures will sharply drop as
the cold front will come through our region at around 5pm. By 7pm most areas
around the region will have rain showers and temperatures will be in the low to
mid 40s. Winds will pick up with gust of 25 mph possible.
Monday Night/Tuesday morning: The big question mark of the
forecast, whether or not a changeover to sleet will happen is very hard to tell
at this point as it will come down to a difference of a degree or two in the
end. For now anticipate rain continuing through the overnight hours with
temperatures remaining in the high to mid-30s until 5/6am. At this point the
radiative cooling near the surface may leave conducive conditions for sleet to start
to fall. Roadways and sidewalks may be slick especially before sunrise.
Temperatures will cool until sunrise with temperatures at 7am for Fairfax are to be at or around the freezing mark. Accumulations in the worst case scenario
will be around a ¼ of an inch of frozen precipitation (Note: No Snow for this
system!)
Tuesday Midday: Temperatures will warm slightly by the early
morning hours and a change back to rain will be highly likely by 10am, with 1pm
being the absolute latest time for a switch back to rain. The heaviest of
precipitation is also predicted to be in those early morning-midday hours. This
is something to keep in mind as this system develops. Temperatures will be
stable in the mid-30s throughout the region (subject to change!)
Tuesday afternoon/evening: Rain may continue all day if the
system lingers, which some models have as a distinct possibility. A slim chance
of a change back to sleet or a freeze of the rain already fallen is a factor
looking ahead to Wednesday. Though most likely this will end as a rainstorm as
it had started. Temperatures again will remain in the mid to low 30s throughout
the region.
Right now I will put this as Low Impact. But this very well change within 12 hours. I will put the chance of freezing rain and sleet at 60% for Tuesday morning. Of course the western sections of our region, especially those in higher elevation have a better chance of more sustained frozen precipitation totals.
Another update will come either tonight or tomorrow morning.
So stay tuned and I will be sure to keep you posted!
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