National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KLSX 101127
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
627 AM CDT Mon Mar 10 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 302 AM CDT Mon Mar 10 2014

Look for another warm spring day with highs ranging from the mid 60s
to the lower 70s thanks to persistent southwest to west winds,
minimal cloud cover, and good diurnal mixing.

Kanofsky

.LONG TERM:  (Tonight through Sunday)
Issued at 302 AM CDT Mon Mar 10 2014

(Tonight-Wednesday)

Today`s tranquil dry weather and above normal temperatures will
persist tonight and into Tuesday. Some cooler air is forecast to
backdoor into northern sections of the CWA during the afternoon
which will hold max temps in the 60s over this part of the CWA.
However, the unseasonably mild air will dominate the remainder of
the FA, and 70s should be common along and south of the I-70 corridor.

However, this winter just doesn`t want to let go, and it
it appears another round of wintry conditions are on the way for
parts of the CWA on Tuesday night. Anyway you slice it, after 3
very mild days the upcoming change on Tuesday night is going to be
dramatic, with strong northerly winds, sharply falling temps, and
rain changing to snow across much of the CWA.

The cooler air that works into northern parts of the CWA on Tuesday
will intensify the baroclinicity over the area, which in turn will
allow for rapid intensification of a surface low on Tuesday night as
a strong (and well-advertised) upper trof approaches the region. In
spite of the relatively mild temps of Tuesday afternoon, all of the
short range guidance indicates rapid lower tropospheric cooling
taking place Tuesday night as the storm intensifies/winds up, with
freezing levels dropping rapidly enough that the precipitation will
be changing over to snow.  This type of situation...where ams cools
to critical levels in situ...is one of the more difficult snow
forecast situations, and in this case it is made even more
problematic due to 3 days of well above normal highs which will
generate some fairly warm ground temps.

While much of the qpf will fall with low level temps warm enough
for rain, 00z guidance continues to support earlier thinking that
greatest sustained precip with low level temps cold enough for all
snow will be over the northern third of the CWA, and rough
estimates of snowfall still suggest accumulations in the 1 to 2
inch range. It remains to be seen if snowfall intensity will be
great enough to overcome the melting due to the warm ground, but
these numbers still look like a good starting point.

Some minor accumulations are not out of the question as far
south as the I-70 corridor, but due to late changeover surmise
that any accumulations in this area will be spotty, and primarily on
grassy areas.

It still appears that precip will wind down fairly rapidly Wednesday
morning, with windy and cold weather continuing throughout the
day.

(Thursday-Sunday)

Temperatures should rebound fairly quickly during the latter half of
the work week.  With a fairly strong southwest low level
flow/persistent warm air advection, and a good deal of afternoon
sunshine, expect highs to return to the upper 50s and lower 60s by
Friday.

Colder air drops into the area next weekend as broad trof develops
over Great Lakes and New England.  This will be followed by
shortwave dropping into the central CONUS from the Pacific NW,
with a chance of precipitation with this feature in the Saturday
night/Sunday time frame.

Truett

&&

.AVIATION:  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 615 AM CDT Mon Mar 10 2014

VFR through the period. LLWS to diminish after 15z once diurnal
mixing begins. Southwest to west winds decrease tonight and become
light/variable at KUIN invof a weak cold front.

Specifics for KSTL: VFR through the period. LLWS to diminish after
15z once diurnal mixing begins. Southwest to west winds decrease
tonight and turn southerly by tomorrow morning ahead of a weak
cold front.

Kanofsky

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX