Very interesting discussions today from both MEG and JAN
JAN:
The main thing to focus on will be the potential for a strong
surface high coming out of the Canadian Rockies in the
wake of the
lead system, while at the same time, a
low pressure system,
supported by the right
entrance region of the upper
jet, pushes in
from southeast Texas. As this surface high propagates towards the
Gulf Coast region, it will bring along very cold air. Basically, 2
scenarios can play out with this:
*Pattern is more phased and surface high brings big cold, but
air is too dry to support precip and suppresses the low pressure
system to the south and we have dangerous cold to contend with.
*Pattern is less phased and the
low pressure system over
southeast Texas runs into the cold airmass from the surface high and
we have wintry precip to contend with.
Neither is an ideal scenario and is a little beyond the official
forecast period, so we will have to monitor this closely as much
is still uncertain. Guidance shows this playing out sometime
around early next week, with slight differences in timing of the
features at this time. Additionally, tight pressure gradients from
the surface high will also increase concern for
gradient winds,
combined with cold temperatures, we may also need to
watch wind
chills towards the back end of the forecast period and
beyond
MEG:
A significant shot of polar air will move into the region early
next week as a highly anomalous
trough sets up over much of the
central
CONUS. 500mb anomalies are clocking in at least 2 sigma
below on both the GEFS and the ENS. A 3D animation of the
GFS
Stratospheric Polar
Vortex shows a sizable chunk of polar air
breaking off the main
vortex early next week and parking over
North America through at least the middle of next week. As such,
the Weather Prediction Center has highlighted much of the south
and eastern
CONUS for below
normal temperatures the week of
January 20 to 24. Additionally, the LREF guidance is hinting at
a possibility of wintry weather during that same timeframe. Still
too early to clearly identify any wintry weather potential,
however, confidence in bitterly cold conditions is increasing for
the aforementioned week. Definitely something to
watch.