Area Forecast Discussion
Issued by NWS Springfield, MO
FXUS63 KSGF 032101
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
301 PM CST Tue Mar 3 2015
.SHORT TERM...(This Evening through Thursday Night)
Issued at 300 PM CST TUE MAR 3 2015
Despite widespread cloud cover and a foggy start to the day,
temperatures have managed to warm into the upper 40s and low 50s in
most locations this afternoon. The relative warmth will be fleeting,
however, as a strong cold front is taking aim on the region. As of
2 PM, the front stretched from central Kansas to northern Missouri.
The initial wind shift should arrive in the northern reaches of the
CWA later this afternoon, and the remainder of the CWA by mid
evening. Expect gusty north winds behind the front.
Colder air will lag the wind shift by a few hours, though
temperatures will start to drop noticeably by mid to late evening.
Precipitation should begin to develop--in the form of rain--as a
upper level jet strengthens across the area, and lift increases in
response. As the cold low level airmass begins to move into the
region and surface temps drop below freezing, precipitation should
transition from rain to freezing rain for a short time. Then, as
the low level cold becomes deeper with time, expect freezing rain to
transition to a mix of freezing rain and sleet, and then sleet and
snow. Eventually, as the column cools entirely below freezing,
precipitation will change entirely over to snow. This transition to
all snow looks to take place by daybreak for central Missouri, and
most of the remainder of the CWA by mid morning Wednesday. Sleet
may linger into the mid day or early afternoon hours over far south
central Missouri. In addition, a few bands of heavy precipitation
can be expected Wednesday over southern Missouri, where there
appears to be a good signal for deep tropospheric ascent, as a
persistent area of f-gen develops in the low levels, and the
associated ageostrophic circulation combines with the lift from the
right entrance region to the upper jet. There`s some question as to
whether this will occur over northern Arkansas or southern Missouri
(or both), but the potential is certainly there for periods of
rather intense precipitation rates.
Timing of these transitions will be the biggest challenge over the
next 12 to 24 hours. For most locations, I think freezing rain will
transition fairly quickly to the wintry mix, but the mix may linger
for a bit, with the potential for somewhat significant sleet
accumulations (half inch or greater) over south central Missouri.
It`s important to keep in mind that a degree or two difference in
temperature at the surface as well as aloft will make all the
difference in precipitation type, and resulting accumulations. In
addition, we still expect that accumulation will be hampered
somewhat by the effects of UV making it through the clouds given a
relatively high sun angle, though it`s not clear just how much this
will impact things. No question that the number of moving parts in
this forecast makes it a bit of a low predictability setup.
So, with all said, it appears that a glaze to 0.05-0.07 inches of
freezing rain will be possible during the transition period, with
the bulk of this occurring along and south of I-44. For the
combination of sleet and snow, amounts look to range from 3-6 inches
over south central Missouri, to 2-4 across the I-44 corridor, a
dusting to 1 inch across the U.S. 54 corridor. Given the
aforementioned mesoscale banding potential, locally higher and lower
amounts are likely. With the expected mix, have upgraded the Winter
Storm Watch to a Warning, and added a few counties along the
northwestern edge. North and west of the Warning, an Advisory will
be in effect. The only counties that will be left out of headlines
for now will be the northwestern-most tier (Bourbon, KS to Morgan),
as snow amounts look to be quite light there.
Precipitation should end late Wednesday night, with high pressure
moving into the area by Thursday morning. With that high and fresh
snow, it should be a fairly chilly start to the day Thursday.
.LONG TERM...(Friday through Tuesday)
Issued at 300 PM CST TUE MAR 3 2015
A welcome pattern change is expected beginning Friday and persisting
into next week. The flow aloft deamplifies considerably, though not
becoming completely zonal in nature, with a flat ridge building into
the area early next week. As a result, a warming trend is expected.
Southwest winds will edge temperatures back to near average by
Saturday, with above average temperatures on tap for Sunday into
early next week. A front or two will traverse the region during this
time frame, however moisture is lacking and the brunt of any airmass
changes will be focused to our east.
.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1123 AM CST TUE MAR 3 2015
IFR conditions will be the rule this afternoon, with gusty
southwest winds expected ahead of an approaching front. Exact
timing of the front will be a challenge, but mid evening looks to
be the rule for now.
As that front passes, expect a period of gusty north winds. In
addition, areas of rain will develop across the region, with a
transition to freezing rain and then a mix of sleet, snow, and
freezing rain as temperatures cool. A change to all snow is then
expected tomorrow; that change should occur during the mid morning
hours for SGF and JLN, and late morning or early afternoon for
BBG. Again, exact timing is a challenge. Once the change to all
snow takes place, expected widespread IFR or LIFR vis.
MO...WINTER STORM WATCH from Wednesday morning through late Wednesday
night FOR MOZ082-083-092-096>098-104>106.