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Office: LSX

FXUS63 KLSX 171202

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
702 AM CDT Sat Mar 17 2018

.SHORT TERM...  (Through Late Tonight)
Issued at 319 AM CDT Sat Mar 17 2018

A surface low was located across central MO at 07z per MSAS MSLP
analysis, and the low pressure system's primary upper PV anomaly was
located near the MO/IA border. A secondary PV anomaly was located
slightly farther to the west and north over NEB based on RAP 1.5 PVU
fields and water vapor imagery. The entire system will continue
moving eastward today while simultaneously weakening as an upper
ridge builds across the central CONUS.

As the upper vort centers move across the region during the day,
they may support sprinkles or light rain showers across the northern
half of the CWA, especially over northeastern MO and west central
IL. Meanwhile, the trailing cold front which was moving through the
area early this morning will briefly stall to the south of the area
until a surface high pressure center builds from the northern plains
into the Great Lakes tonight and pushes the boundary farther

The combination of a slightly cooler post-frontal air mass,
northwesterly winds and low-level CAA, and persistent cloudiness
across at least the northern half of the area today will yield high
temperatures which should be within a few degrees of yesterday's
highs for most locations. The extreme southern and southeastern
edges of the CWA may get a bit warmer than currently forecast
because they will have a warm start to the morning ahead of the
frontal passage and could remain mostly clear for long enough to see
a quick warm-up ahead of the front. Overnight lows ranging from the
low 30s in NE MO to the upper 30s in SE MO look reasonable given
that surface winds will retain a northerly component through at
least 09z.


.LONG TERM...  (Sunday through Friday)
Issued at 319 AM CDT Sat Mar 17 2018

Surface ridge to move off to the east during the day on Sunday. So
will see winds become easterly. In the meantime, next system to
begin lifting out of the Central Plains so clouds and low level
moisture will be on the increase. As for high temps, they will be in
the 50s Sunday.

00z model runs continue to have differences in strength, timing and
placement with this system. NAM is the furthest north while ECMWF is
farthest south and fastest. For now will go with NBM. Will see
activity develop and spread northward Sunday night. Some weak
instability with this system, so added thunder mention for portions
of southern MO during this time. Better chances of showers and
storms as main system moves through region on Monday. Rain to taper
off by daybreak on Tuesday as system exits. Also, with some colder
air filtering in on back side of system, will see rain become mixed
with snow before ending.

Cooler and drier weather expected Tuesday with highs only in the
40s. Weak surface ridge to build in by midweek with temperatures
moderating. Could see some scattered showers/flurries Tuesday
through Thursday due to active northwest flow aloft, but moisture
will be limited and hard to pin down timing of these shortwaves, so
kept forecast dry for now.

Beyond that, next best chance for rain will be Thursday night
through Friday.



.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 628 AM CDT Sat Mar 17 2018

SPECIFICS FOR KCOU, KUIN: An area of IFR to MVFR clouds is
wrapping around an upper disturbance. Based on upstream
observations, short periods of IFR cig/vis are possible at KUIN
during the first 0-4 hours of the valid TAF period. A few
sprinkles or light rain showers will be possible during the first
0-6 hours. Conditions are expected to remain at or below MVFR for
at least the first 0-12 hours of the TAF period.

SPECIFICS FOR KSTL, KSUS, KCPS: A very brief period of VFR
conditions can be expected at the St. Louis area terminals between
1130-1230z, but satellite imagery shows that this improvement will
be very brief indeed. A solid deck of MVFR clouds is wrapping
around an upper disturbance and will reach the St. Louis metro
area shortly after 12z. MVFR ceilings are then expected to persist
for most of the valid TAF period. IFR conditions are possible
after 18/06z, but confidence was too low to include IFR during the
last 6 hours of the TAF period.






Office: SGF FXUS63 KSGF 171011 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 511 AM CDT Sat Mar 17 2018 ...12z Aviation Forecast Update... .SHORT TERM...(Today and tonight) Issued at 124 AM CDT Sat Mar 17 2018 Quiet weather is expected today with seasonable temperatures. The only area that may see a little more gloomy skies will be across central Missouri into the far northeastern Ozarks Region. Clouds on the back side of the exiting low pressure system will move through that area. The cloud cover may keep the temperatures in the 40s. The rest of the area will see sunshine with highs in the upper 50s to lower 60s. High pressure moves on by the region tonight with light winds and clear skies. Temperatures will fall into the middle 30s which is about average for this time of year. .LONG TERM...(Sunday through Friday) Issued at 124 AM CDT Sat Mar 17 2018 Our next storm system quickly moves out into the Central Plains Region Sunday into Monday. Moisture will surge northward late Sunday and showers will develop from southwest to northeast across the region. Sunday will not be a complete wash out but expect rain likely by Sunday evening along a retreating warm frontal boundary. There could be a few elevated storms along the warm front and could be just enough instability for some small hail. There is a marginal risk for a strong storm or two Sunday evening into Sunday night across portions of southeast Kansas into southwest Missouri. It will become breezy again Sunday night into Monday with a strong low pressure system over Kansas. Rain and isolated storms will be likely through Monday as the system slowly moves eastward. The center of the system moves over the area Monday evening and Monday night with showers. Most of the showers will end Monday night but there could be a few leftover into Tuesday morning on the back side of the exiting shortwave trough. Tuesday will be cooler and below average lasting into Wednesday. We will be dry for Wednesday and Thursday ahead of our next storm system which will be more rainfall by the end of the week. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 439 AM CDT Sat Mar 17 2018 VFR conditions will continue over the next 24 hours for most of the area. There may be a deck of MVFR ceilings across central Missouri today but will not affect the TAF sites. Winds will start out westerly and gradually shift northwesterly today and then notherly this evening between 5 and 10 knots. There are no aviation concerns for the next 24 hours with this update. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...Griffin LONG TERM...Griffin AVIATION...Griffin
Office: EAX FXUS63 KEAX 171110 AFDEAX AREA FORECAST DISCUSSION National Weather Service Kansas City/Pleasant Hill MO 610 AM CDT Sat Mar 17 2018 .Discussion... Issued at 250 AM CDT SAT MAR 17 2018 Satellite imagery and surface observations show the nearly vertically stacked storm system tracking over the area early this morning. Low clouds are spilling into the region on the backside of the low across eastern KS and western MO. There may be some lingering light precipitation across northern to northeastern MO this morning, but other than that, it looks dry and cool today with highs climbing into the 40s north and the 50s in our southwest. Temperatures will moderate into the 50s and low 60s on Sunday ahead of the next storm system that should impact the area beginning Sunday night and persisting through the day Monday. There are some significant differences in the models for this system, despite them being in agreement with taking the surface low to our south. The NAM is a clear outlier here. It has a little bowling ball of a PV anomaly move over the area and is much deeper with the upper low. This strong forcing seems to feed back into the intense band of snow it produces across northern MO. Forecast soundings in this band show very steep lapse rates develop with some instability noted. In essence, there is dynamic cooling of the column due to the strong upward vertical motions. This results in a narrow swath of a foot+ of snow. At this point, this seems very unlikely given the cutoff or closing off of the upper low. The GFS, Canadian, and the ECMWF all seem much more reasonable and don't produce the dynamic cooling that results in a narrow swath of heavy snow. Rather, they present a much more reasonable widespread rain event where the area could see half an inch to three quarters of an inch of much needed rain. So have basically discounted the NAM at this point for this time frame. Through the rest of the forecast, there should be a general warming trend as temperatures warm from the 40s on Tuesday to the 50s and 60s by Thursday and Friday. There may also be several chances for precipitation. These look less widespread than the Monday system and models are in less agreement with the timing and areas of precipitation. Most of these chances seem to come from the GFS which moves several small systems through the area through Friday. Given the lack of agreement on these smaller systems, would not be surprised to see subsequent forecasts lower/remove these pops. && .Aviation...(For the 12Z TAFS through 12Z Sunday Morning) Issued at 611 AM CDT SAT MAR 17 2018 Low MVFR ceilings are expected to persist through the morning hours before lifting to MVFR by the afternoon. Ceilings should become VFR by late in the afternoon. Winds will be from the northwest this morning but will gradually weaken and become variable as high pressure tracks to the north and to the east. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...CDB Aviation...CDB