Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/09/20
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
909 PM CST Wed Jan 8 2020
Issued at 855 PM CST Wed Jan 8 2020
Gusty winds particularly across and on the western slopes of the
Coteau have led to areas of drifting and blowing snow, and an SPS
out until 04z was issued in response. Winds will decrease tonight
as low pressure shifts eastward. As for freezing drizzle
potential, low level moisture doesn`t appear to be deep enough and
there`s a lack of favorable upslope flow across the Coteau, so
have kept it out of the forecast.
UPDATE Issued at 537 PM CST Wed Jan 8 2020
See updated aviation discussion below.
.SHORT TERM...(This Evening through Thursday Night)
Issued at 317 PM CST Wed Jan 8 2020
Southeasterly winds of 15 to 30 mph with gusts of 40 mph will
continue across the region through this evening. The warm air
advection, along with cloudy skies, will keep lows from dropping
much tonight. Am a bit concerned with low temperatures in the
northeast as the current forecast is a couple degrees warmer than
21Z observations. Temperatures should reach their day time high
around 0Z, with temps becoming steady, or slowly rising thereafter.
Patchy freezing drizzle or flurries could be possible tonight,
mainly of the I29 corridor. HRRR buffer soundings indicates good low
level moisture up to 1 KM, which is not the best for freezing
drizzle. With low forecaster confidence, will not mention freezing
drizzle or flurries tonight.
Surface low pushes across the region tonight, with winds shifting to
the west, then northwest. The northwest winds will bring colder air
into the region, mainly during the mid to late afternoon hours.
Highs on Thursday should reach the 20s and low 30s. Warmer temps are
possible of the limited snow cover area in the southwest CWA. Low
temperatures Thursday night are rather challenging. An Arctic high
pressure northwest of the region will filter cold air into at
least the eastern half of the CWA. A weak storm system will move
into the region from the west with cloudy skies and light snow
possible after 6Z Friday. Lean toward the HREF for lows Thursday
night, which should range in the single digits on either side of
zero. Would not be surprised if locations in northeastern South
Dakota and western MN drop to 10 degrees below zero. Snow
potential in the western CWA is not all that exciting. As of now,
a dusting to an inch could be possible with higher amounts along
and south of I90.
.LONG TERM...(Friday through Wednesday)
Issued at 317 PM CST Wed Jan 8 2020
A somewhat energetic mid-level pattern is expected across the CONUS
during the period. Energy will continue to dig into the western
CONUS, and then eject east into the Plains. None of these systems
look very strong at this time, with only light amounts of snow
expected. The highest chances for measurable snow during the period
would probably favor early next week as a system lifts out across
the Central/Northern Plains. Temperatures are the bigger story. A
push of arctic air will slide into the area for Friday, and stick
around for a couple days. A stronger intrusion of cold air looks
possible for the end of the period, or about the mid to late part of
next week. H85 temps as cold as -25C look possible at that time.
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 537 PM CST Wed Jan 8 2020
Gusty southwesterly winds will continue this evening before
diminishing tonight. Additionally, LLWS is possible this evening
at ABR and ATY. MVFR ceilings have already moved into MBG, and may
build into ABR and ATY by Thursday morning as well.
Area Forecast Discussion
National Weather Service State College PA
1048 PM EST Wed Jan 8 2020
High pressure moving over the area will stop the snow showers
this evening and bring dry and tranquil conditions for Thursday.
A warm up starts on Friday, followed by several bouts of rain
for the weekend as waves of low pressure ride northeast along a
nearly stationary frontal boundary just to our west.
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
Squalls continue to decrease in intensity and have become much
more cellular with the addition of the day time heating. SHSN
over the nrn tier are all lake enhanced now and should go into
the first part of the night. Recent HRRR and RAP guidance keeps
the SHSN over the N going thru 03Z, but rapidly decrease the
srn showers after 22Z. Temps behaving and have even risen
briefly to 40F at CXY and a few smaller/backyard sites around
Expecting the snow showers to diminish quickly as we lose
heating and vorticity advection becomes negative late this
aftn. Most radar returns should be gone by 7 PM.
.SHORT TERM /MIDNIGHT TONIGHT THROUGH THURSDAY NIGHT/...
The upper flow becomes less cyclonic this evening and the long
N-S ridge of high pressure slides in from the west. The wind
will take a while to diminish, though, as the ridge is sharp.
Expect many places to be calm after 3 or 4 AM, but a light SE
wind kicks in very quickly around sunrise, also because the
ridge is sharp and moving along.
Will undercut guidance temps overnight as the clearing and
snowpack should set us up for a drop when/if the wind dies off.
It will be the few hours right before sunrise that we should
have the bast chance to crash.
Thursday should be dry under high pressure. Temps still near
normal for daytime highs. S/SE flow does get stronger thru the
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
High pressure will drift offshore Friday with southwesterly flow
setting up around the high. A plume of moisture will extend from
the Gulf of Mexico to the Great Lakes circulating around the
high off the East Coast and low pressure over the Plains.
Intermittent showers can be expected across the northwest zones
Friday, while the southeast will likely stay dry. A few pockets
in the northern valleys may be cold enough Friday morning when
the rain begins for a brief period of wintry mix, but
temperatures should quickly rise above freezing. Rain will
continue across the northwest Saturday while unseasonably mild
air moves into Pennsylvania. Temperatures will likely be 20 to
30 degrees above normal Saturday and Saturday night. A cold
front will move across Pennsylvania Sunday which will bring
temperatures down some into Monday, but we still look to remain
above normal for this time of year. Next system may bring some
clouds and chance of rain Tuesday or Wednesday.
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
00z update... Any lingering restrictions (lower ceilings and
snow showers) at KBFD and KJST should be short-lived at this
point, with improving conditions likely by 03-05z.
Otherwise, VFR/unrestricted conditions are expected across
central PA through the day Thursday.
Gusty NW winds this evening, will diminish late tonight, then
turn S-SE by Friday afternoon at 5-10 kt.
Thu...A light wintry mix possible late at night at KBFD, with
ceiling restrictions possibly developing elsewhere across
Fri...Restrictions probable in lower ceilings, rain, and fog. A
wintry mix possible early in the day at KBFD.
Sat...Restrictions again expected, with rain and lower ceilings
Sun...Periodic restrictions possible in scattered rain and snow