000
FXUS63 KSGF 022057
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
257 PM CST Mon Mar 2 2015

.SHORT TERM...(This Evening through Tuesday)
Issued at 256 PM CST MON MAR 2 2015

A quiet weather day is underway across the region this Monday
afternoon, with temperatures rising into the mid to upper 30s under
mostly cloudy skies.  Light southeasterly winds will become
southerly and increase through the evening and overnight hours
tonight, as high pressure pulls east and a surface low rapidly
deepens in the lee of the Rockies.

This southerly flow will begin to advect a (relatively) more mild
airmass into the region overnight, characterized by low to mid 30s
dewpoints.  As this airmass moves over the existing snow, fog and
drizzle should be a good bet from this evening through the overnight
hours.  Right now, it looks like winds should be strong enough to
keep things mainly drizzle vs. fog, though some reduced visibility
is certainly possible along the higher terrain of the Plateau.
Temperatures this evening should fall a couple of degrees, before
leveling off and then rising during the pre-dawn hours.  While a few
spots across the eastern Ozarks may briefly dip below freezing
tonight, it appears that temperatures should rise above 32 before
precipitation begins.  Thus, will not include mention of any
freezing drizzle at this time.

Drizzle should generally give way to scattered rain showers during
the day Tuesday, as temperatures warm into the low 50s ahead of an
approaching front.  The trend over the last few days has been
slightly cooler with less available instability, with this morning`s
12Z guidance all but zeroing out CAPE.  As such, will go ahead and
remove thunder mention from the forecast for Tuesday.  While an
isolated rumble or two isn`t entirely out of the question, chances
just appear to be too low to justify mention.

.LONG TERM...(Tuesday Night through Monday)
Issued at 256 PM CST MON MAR 2 2015

The cold front should then sweep across the area from northwest to
southeast Tuesday during the late afternoon and evening hours, with
much colder air building in behind the front.  Precipitation will
initially be shunted southeast with the front, but then should build
back to the north in a post-frontal fashion as very strong upper
level jet streak backbuilds from the Great Lakes into the Ozarks and
southern Plains.  Combined with what should be several well
developed areas of low and mid level frontogenesis associated with
the front, this looks to be a good setup for deep tropospheric
ascent across the region, with the potential for several bands of
moderate to even heavy snow given the f-gen.  Right now, the biggest
challenge remains pin-pointing where these bands setup; it does
appear that areas south of I-44 will be most favored for the higher
snow accumulations, with lesser amounts north.  There will be a sharp
gradient to the northern edge of the snowfall, so locations along
the I-44 corridor, including Joplin, Springfield, and Rolla, should
be prepared for the possibility of significant changes to the
forecast based on just a 20-30 mile shift in the system.

Along with determining the areas of heaviest precipitation, two
other factors will likely have an impact on the snowfall forecast.
The first will be the possibility of mixed precipitation as the very
cold low level frontal airmass undercuts warmer temperatures aloft
Tuesday night and early Wednesday, resulting in a temporary warm
nose.  This may be enough to result in a few hours of a mix of snow,
freezing rain, and sleet, before things change over entirely to
snow.  The other issue will be the early March sun angle given what
will be mainly daytime accumulation on Wednesday.  This will
probably cut down amounts compared to what would otherwise
accumulate if it were after dark.

So, with all that said, will be going with a broad 3-5" area of snow
south of I-44, with lesser 1-3" amounts along and north of the
Interstate.  Given the expected banding, locally higher and lower
amounts are likely.  Since confidence is pretty low that any
locations will reach the 6" mark, will hold off on a Winter Storm
Watch for now.  Will highlight the expected winter event with a
Special Weather Statement.

After a cold night Wednesday night and a rather chilly day on
Thursday, guidance continues to suggest a somewhat significant
pattern change heading into the weekend and next week.  The overall
CONUS pattern looks to translate east, meaning that the cold eastern
trough that has been affecting the region for the last month or two
will give way to a warmer and drier western US ridge.  This should
allow temperatures to rise into the 50s by the beginning of next
week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1136 AM CST MON MAR 2 2015

We will continue the trend for lowering ceilings and visibilities
during the overnight and morning hours as moisture increases ahead
of several upper level disturbances embedded within southwest flow
aloft. Will delay the onset of precipitation by four to six hours
based on current conditions and model guidance trends. However,
with temperatures above freezing over snowpack across the area,
especially at SGF, have trended visibilities below current
guidance.


&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$

SHORT TERM...Boxell
LONG TERM...Boxell
AVIATION...Terry