Scientific Forecaster Discussion
Area forecast discussion
National Weather Service northern Indiana
1227 am EST Friday Nov 28 2014
issued at 530 PM EST Thursday Nov 27 2014
Lake effect snow showers will continue to impact southwestern
lower Michigan and northwestern Indiana tonight. Expect slick
roads and reduced visibilities associated with the heaviest snow
bands...especially along I-94 between Benton Harbor and New
Buffalo and along I 80-90 west of I-69. Otherwise...expect cloudy
skies and lows in the teens.
issued at 728 PM EST Thursday Nov 27 2014
Lake effect snow band has been persistent across
Berrien/Cass/Elkhart counties since around 21z with 2-4" of new snow
reported in that time in that area. Snow band still expected to
weaken this evening as ridge builds in and winds back/inversion
lowers... so only around another inch expected in this area.
Updated the west-southwest to extend area into Elkhart and time to 10pm.
Short term...(this evening through friday)
issued at 346 PM EST Thursday Nov 27 2014
A single band of heavy snow that had been working its way south
along the East Shore of Lake Michigan was moving inland over
Southern Lower Michigan...and had generally weakened where the band
had moved over land. This band had produced up to 8 inches of snow
between Ludington and Muskegon. Other snow bands were developing
over the lake northwest of Berrien County were Delta T values had
risen to around 20c. There was good dendritic growth in the the
cloud layer producing large flakes that had fallen earlier today. Am
planning to keep the lake effect Snow Advisory in effect through
early this evening for Berrien...Cass and St Joseph counties in
lower Michigan. Inversion heights will fall rapidly this evening as
winds back to the west causing lake effect snow showers to diminish.
Although lake effect snow will be diminishing...12km NAM supports a
chance for snow over northern areas Friday during the day as
isentropic lift increases per 290k surface and mixing ratios rise to
near 3 g/kg. Therefore...kept a chance for snow over north and
northeast areas Friday.
Long term...(friday night through thursday)
issued at 346 PM EST Thursday Nov 27 2014
Relatively benign synoptic weather pattern still expected through
the long term. Warm air advection underway Friday night. Best forcing
for any precipitation looks to move north of the area but did maintain a very
low chance pop far northeast. Impressive warm air advection on tap
for Saturday with 850mb temperatures rising into the teens.
However...surface warming will still be tempered as model soundings
show a very strong inversion and indications of low cloud deck
remaining across the area. Still should feel much warmer with
readings well into the 40s and run at lower 50s most plausible in
the southwest where warmer thermal ridge and potential for mixing
and clearing are best. A warm Saturday night expected with lows
staying in the 40s. 850mb temperatures cool on Sunday ahead of main surface
cold front but very warm start to the day should help maximum temperatures
reach the 50s before falling late Sunday into Sunday night. Precipitation
chances remain low but light showers or quantitative precipitation forecast still indicated by
models so again allowed low chance probability of precipitation to ride.
Uncertainty continues for next week...especially middle to late week
with significant model differences. Cold front should sag south of
area on Monday with cooler temperatures...a chance for light precipitation near
front...and a very low chance for light lake effect showers behind
front Monday. Gem and European model (ecmwf) show a reinforced shot of cold air
coming in middle week while GFS develops a strong low in the plains and
surges a warm front north. Preference at this time lies closer to
European model (ecmwf) and Gem so trended forecast variables in this direction.
GFS solution would indicate a chance for moderate rainfall while
European model (ecmwf)/Gem would be cold with snow showers.
Aviation...(for the 06z tafs through 06z Friday night)
issued at 1226 am EST Friday Nov 28 2014
VFR conds expected through the period. Lake effect continues to diminish rapidly
in response to backing ll follow ahead of subtle disturbance embedded
within potent ND jet streak and subsidence entrainment of dry air
aloft. In fact based on 00z upstream radiosonde observations from kdvn and kilx top down
saturation underneath robust middle level echo will struggle to produce
even a potential flurry this afternoon and will only carry a broken middle cloud
deck for the majority of black Friday.
Lm...Small Craft Advisory until 4 am EST early this morning for
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