Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Springfield MO
635 PM CST Sat Feb 28 2015

..Winter Weather Advisory upgraded to a Winter Storm Warning for
portions of the Ozarks...

Update...
issued at 619 PM CST Sat Feb 28 2015

Calls around and social media reports indicate that 4-5" of snow
has now fallen along and north of the I-44 corridor and along and
east of the U.S. 65 corridor. The snow has started accumulating
much more efficiently with the setting sun. With the back edge of
the most organized precipitation just now getting to the Kansas/MO
line, we still think another 1-3" of snow will fall...especially
along and north of the Ozark Plateau and east of U.S. 65. With
that being said, we have upgraded to a Winter Storm Warning from
Polk and Greene counties...northeast into the Lake of The Ozarks
and Salem region.

While snow will become lighter from west to east later this
evening, we are expecting the potential for a light wintry mix
overnight and into Sunday morning. Radar and satellite trends as
well as observations indicate freezing drizzle, very light
freezing rain, and even some light sleet pushing in from eastern
Oklahoma and Kansas. Minor ice accumulations will therefore be
left in the forecast as we head into later tonight and Sunday
morning.

&&

Short term...(this evening through Sunday night)
issued at 307 PM CST Sat Feb 28 2015

A large area of snow has blanketed all of the Missouri Ozarks and
extreme southeastern Kansas as of mid afternoon. Visibilities were
pretty much below one mile over all areas...with occasional
observations indicating quarter mile visibilities with heavy snow.
Snowfall accumulations up through 3 PM have been in the 1-3"
range. We suspect that some locations across extreme southeastern
Kansas and west-central Missouri may be in that 3-4" range.

As we head into late this afternoon and this evening, short term
models are beginning to change their tune a bit. Both the rap
and the hrrr have somewhat backed off on a secondary band of snow
developing along the I-44 corridor this evening. Even the 18z NAM
has trended this way. Instead, models gradually take the large
area of moderate to occasionally heavy snow to the east and
northeast with the back edge of the heavier snow moving east
across the Ozarks this evening. This would tend to make sense as
low level isentropic upglide and a weak upper level jet coupling
structure shift towards the mid Mississippi Valley. We will still
have to watch for some banding of snow as models do indicate some
slugs of increased 700 mb frontogenesis...especially along and
north of the I-44 corridor.

As we head into later tonight, the main area of snow will have
shifted east of the area. Pockets of light snow and flurries
will be left in its wake. While snow intensity will be on the
downward trend this evening (again from west to east), it will
tend to accumulate more efficiently given that the sun will have
set. Models are also indicating perhaps some loss of cloud ice
later tonight. Additionally, models still bring a warm nose into
southern Missouri by late tonight. Thus, we are continuing a
mention of either light freezing rain or freezing drizzle.

This trend will then continue into Sunday morning with pockets of
light snow and drizzle/freezing drizzle. We have slowed the
progress of the surface freezing line to the north by a few
hours...which does keep the door Open A bit longer for minor ice
accumulation. One thing we will have to watch very closely is what
will be a good setup for a banded snow event from late tonight
into Sunday morning up towards I-70. Models continue to indicate
strong 700 mb frontogenesis and available negative epv becoming
juxtaposed with a favorable upper level jet streak. If this
materializes, it could put down a narrow swath of additional
heavier snowfall. While this could glance our central Missouri
counties, confidence is higher that it will remain just north of
the area. Once we get into Sunday afternoon and especially Sunday
night, the primary precipitation will be shifting east and
southeast of the region.

As for storm total ice and snow amounts, we have not changed much.
Any ice accumulations are still expected to remain at or below
five-hundredths of an inch. 1-3" of snow is expected across
south-central Missouri. Accumulations near and north of the I-44
corridor will be in the 3-6" range. We still think a few isolated
reports of around 7" will be possible. Given that any 6-7" amounts
are expected to be isolated (if they occur at all), the current
Winter Weather Advisory will be left intact.

Long term...(monday through saturday)
issued at 307 PM CST Sat Feb 28 2015

By Monday morning, precipitation should push south of the region,
at least temporarily, as high pressure noses south from the
Dakotas. Highs on Monday look to reach the upper 30s in most
locations.

Precipitation will then return to the area Monday night into
Tuesday, though at this point it appears that temperatures
should be above freezing by the time rain begins to fall Monday
night. Rain will continue through much of the day Tuesday, as low
pressure at the surface deepens and lifts north across Kansas and
northern Missouri. Breezy southwest winds during the day Tuesday
will help temperatures warm into the low to mid 50s. Will continue
to include a mention of thunder in the forecast for Tuesday, with
guidance suggesting a couple hundred j/kg of cape making its way
into the County Warning Area.

A strong cold front will then sweep across the area Tuesday
afternoon and evening, with colder air quickly advecting into
the area Tuesday night. We will need to carefully watch the
potential for Post frontal snow Tuesday night and Wednesday, as
lift from a secondary trough axis may be enough to result in areas
of snow on Wednesday. As it stands right now, the highest snow
potential for Wednesday looks to be south of I-44, though this
will be highly dependent on the eventual location of the front.

The upper level flow will then flatten out a bit, with
southwesterly flow developing at the surface for the end of the
week into next weekend. This is suggestive of warmer temperatures
for the end of the week, with highs perhaps (finally) approaching
climatological averages by this time next weekend.

&&

Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 1149 am CST Sat Feb 28 2015

IFR and LIFR conditions will continue this afternoon and evening
across the region as moderate to at times heavy snow affect the
terminals. Prevailing conditions will likely be just above Airport
minimums at sgf and jln, but dips to or below mins are likely
if/when bands of the heaviest snow move overhead.

Snow intensity should decrease somewhat later tonight, though cigs
will remain low. A south to north transition to a wintry mix of
snow, rain and freezing rain is expected at some point late
tonight, with an eventual changeover to just rain around mid day
tomorrow as temperatures rise above freezing. While this
transition has been indicated in the tafs, confidence in exact
timing is very low.



&&

Sgf watches/warnings/advisories...
MO...Winter Weather Advisory until noon CST Sunday for moz055-056-066-
067-077-078-088-089-093>098-101>106.

Winter Storm Warning until noon CST Sunday for moz057-058-
068>071-079>083-090>092.

Kansas...Winter Weather Advisory until noon CST Sunday for ksz073-097-101.

&&

$$

Update...schaumann/Cramer
short term...schaumann
long term...boxell
aviation...boxell

National Weather Service Glossary of Abbreviations