Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kctp 152335 

Area forecast discussion
National Weather Service State College PA
635 PM EST sun Dec 15 2019

the next weather system will move into southern portions of the
area overnight and slowly spread north on Monday. This system
will bring a mixed bag of winter precipitation with it until
temperatures warm up above freezing later on Monday. Please use
caution when travailing across southern Pennsylvania late
tonight and Monday. An upper level trough will swing through
the northeast US during the middle of the week, then high
pressure will likely build in to end the week. Cold temperatures
will begin to moderate by late in the work week.


Near term /through Monday/...
les showers are decreasing early tonight over the northwest
mountains. Still a few moderate bursts fell late this afternoon
creating locally slippery conditions and blowing snow along and
north of Route 6. The lake effect will wind down by mid evening
with very brief clearing ahead of the next weather system.
Snow is expected to streak across the southern tier late tonight
through Monday morning with a slippery start to the day expected
across my southern tier counties. Briefings and social media
posts have been updated to reflect this. Elsewehere, look for
increasing clouds late.


Short term /Monday night through Tuesday/...
messy start to the southern zones with approaching low pressure
system. After initially starting as snow, as has been the case
most of the last month, mild air will quickly work its way in
just aloft to change the phase of the precipitation to sleet and
ultimately freezing rain and then rain. With the heating of the
day and milder air working in, temperatures will rise above
freezing and the wintry precipitation threat will end in the
afternoon, leaving the bulk of the precipitation with this
system as plain rain. Will cover this with a Winter Weather
Advisory for our southern zones. Further north, the storm
system will bring light snow or flurries with it, but it will be
working against fairly dry low layers and rates will be light
throughout much of the event. Low level warming will also turn
any snow into a light wintry mix with lower qpf totals as you
move north.


Long term /Tuesday night through Sunday/...
northern snow/southern rain should taper off Tuesday evening,
as surface wave exits the mid Atlantic coast. The 00z naefs and
ecens both support a period of below average temperatures during
mid week, as an anomalous upper trough swings through the
northeast conus. The flow off of the grt lks briefly appears
favorable for lake effect snow showers across northwest PA
Wednesday, then the arrival of surface high should result in a
period of fair weather through the balance of the work week.

Model spread and forecast uncertainty ramp up toward next
weekend. Much of the guidance has a digging trough approaching
from the Midwest, so anticipate moderating temperatures ahead of
this feature and a possible need to introduce a chance of
rain/snow showers by Saturday.


Aviation /00z Monday through Friday/...
snow showers across the NW continue to produce IFR conds at bfd
and mfvr at kst and kaoo with slow improvement into the evening
expected. VFR should continue elsewhere. Westerly winds will
continue to be brisk, and strongest over the western half.
Sustained speeds around 15 mph will be common, with gusts to
25-35 mph over the western higher terrain, closer to 25 mph
gusts over the east. Winds subside this evening as just about
everywhere remains VFR (the northwest mountains may hold on to MVFR

Next next system slides in from the SW late tonight into
Monday, spreading widespread restrictions back into the region,
with MVFR-IFR ceilings and vsbys in snow. As warmer air changes
precip through a wintry mix and then to plain rain over the
southern half later Monday into Mon night, vsbys will improve
but widespread ceiling restrictions will remain.


Mon...PM low cigs/wintry mix possible.

Tue...low cigs NW, improving conditions elsewhere.

Wed...restrictions likely north/west with snow showers.

Thu and restrictions expected.


Ctp watches/warnings/advisories...
Winter Weather Advisory from 2 am to 4 PM EST Monday for



National Weather Service Glossary of Abbreviations