Scientific Forecaster Discussion
fxus61 kpbz 210629
Area forecast discussion
National Weather Service Pittsburgh PA
129 am EST Thu Nov 21 2019
dry weather and a warming trend will continue today. Some light
precipitation, mostly in the form of rain, will accompany a cold
front tonight and Friday. Another system over the weekend will
provide further rain and snow shower chances.
Near term /through today/...
changes to the midnight update included only a refresh of
temperatures. Satellite imagery shows the slow decay of the
persistent stratocu deck is almost complete. Clearing skies and
light wind over most of the area have allowed temperatures to fall
several degrees below hourly forecasts, while those areas where lower
clouds are still hanging on (mainly around indiana) remain quite a
bit warmer than guidance. Have adjusted temperatures accordingly.
with high pressure settling into the region tonight and mid-level
ridging building, expect the trend to partly cloudy conditions to
continue into tonight. As wind will be light overnight, some patchy
mist may form again towards morning, especially in areas that can
stay mostly clear. Seasonable temperatures mostly around freezing are
Dry weather continues through much of today as the mid-level ridge
axis crosses the region and sfc high shifts to our east. A dampening
shortwave trough is expected to cross the upper Midwest into the
Great Lakes region by this afternoon. At the surface, a weak low will
cross the Great Lakes, pushing a warm front through the forecast area
this afternoon. Warm air advection with southwesterly flow will allow
temperatures to rise into the 50s for much of the County Warning Area -- slightly
above normal for this time of year. Warm air advection will also bring increasing
cloud cover in advance of the cold front.
Short term /tonight through 6 PM Friday/...
the cold front will cross late tonight through early Friday morning.
With the weakening shortwave sliding north of our cwa, and the upper
jet positioned such that the best upper level divergence lies to our
south, it appears that support for lift splits around our region.
Will continue with mainly likely pops for the expected light quantitative precipitation forecast
event. Precipitation will remain liquid into Friday afternoon, before
temperatures aloft become cold enough to allow for snowflakes later
in the day. No accumulation is expected.
Tonight will feature mild temperatures ahead of the front.
Temperatures will initially drop on Friday behind the front, before
steadying out during the afternoon hours.
Long term /Friday night through Wednesday/...
Friday night will feature mainly dry weather under transient ridging.
A stronger shortwave arrives in the middle Mississippi Valley by
Saturday morning and lifts toward our region by the evening hours.
This will bring another round of rain and snow showers to the region
through Saturday night. The weak associated surface low will continue
to dissipate as it crosses Saturday night, with a new coastal system
forming thereafter. Quantitative precipitation forecast amounts will remain minor, with values
generally around a quarter-inch of liquid or less. Any snow
accumulation would be very minor and mostly limited to nighttime
After isolated showers depart Sunday morning, high pressure will
then provide mainly dry weather through Tuesday. Temperatures will
begin to trend a little above normal with generally flat west-southwest flow
aloft. The end of the extended period may feature a strong low
pressure system lifting across the western Great Lakes next
Wednesday, with the possibility of strong wind gusts. This possible
system will need to be watched closely, as it would occur on one of
the busiest travel days of the year.
Aviation /06z Thursday through Monday/...
VFR expected through the day as a ridge transitions over the region.
Low level wind shear will be possible by early evening with a strengthening low level jet as a
warm front approaches...followed by cig restrictions and showers
ahead and along the associated cold front overnight into Friday
low pressure will result in restrictions Saturday afternoon through