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Office: LSX

FXUS63 KLSX 171138
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
538 AM CST Sun Dec 17 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 330 AM CST Sun Dec 17 2017

Large area of light rain continues to slowly move northeast early
this morning across Missouri.  This area is being forced by low
level moisture convergence underneath mid level ascent ahead of a
upper level low.  This area of rain will continue to move northeast
this morning, but models are showing that the band of rain will lose
its areal coverage as it passes through. This will be because the
upper low is opening up so the mid level ascent will weaken at the
same time the low level jet will also be weakening.  Will only keep
a brief window of likely PoPs moving northeast across the area this
morning with mainly dry conditions this afternoon and this evening
as shortwave ridging moves over the area.  Model guidance shows low
level moisture will stay over the area through tonight, with the
potential for patchy fog and some drizzle overnight.

With clouds and the chance of rain, highs will not be as warm today
as they were yesterday, though they will be above mid December
normals.  Went with highs close to both the MOS and SREF mean temps.
Lows tonight will be closer to normal highs.

Britt

.LONG TERM...  (Monday through Saturday)
Issued at 330 AM CST Sun Dec 17 2017

The models are still showing considerable evolution in the upper air
pattern over NOAM over the next 7+ days, and with the 00Z model
cycle the GFS and ECMWF have come into better agreement in the
overall TRENDS. The upcoming week begins featuring a defined split
flow regime with a fast broadly cyclonic flow across the northern
tier and closed low in the southwestern U.S.. By next weekend there
has been an increasing trend of a highly amplified pattern across
NOAM with a vortex in the vicinity of Hudson Bay and southward
extending broad deep trof through the Nation's midsection. In
terms of sensible weather this evolution would largely support
above average temperatures for much of the upcoming week, with
below average temperatures closing out next weekend.

As stated above, the week ahead will feature above normal temps
through Thursday. The big potential caveat to the intensity of the
mild temps on Monday will be clouds. Stratus will likely blanket the
area at daybreak, and maybe some patchy fog/drizzle. Southwest-
westerly lower tropospheric flow will prevail and increase some
through the day, resulting in pronounced WAA and also helping with
the clearing process. The GFS suggests west-east clearing in the
afternoon whereas the NAM is a bit slower from late afternoon through
evening. If the faster solution is correct then highs could be a
good 3-5 degrees warmer than currently forecast. Tuesday will feature
a cold front moving across the area. The front will be located in
the vicinity of the IA/MO border at 12Z, moving to near I-70 by
midday, and clearing the CWA by early evening. Good low level WAA
will continue ahead of the front, and at least immediately behind
the front the air is not all that cold. Thus another day of mild
December temps, around 15-20 degrees above average.

Surface high pressure will continue to settle southward into the
area on Tuesday night, then gradually retreat to the east on
Wednesday. This air mass will be cooler than the preceding days, but
still above average. There has been some model disagreement on the
potential for some light rain late Tuesday night into early
Wednesday associated with southern stream upper low/trof moving from
the southern Plains into and through the lower MS Valley. The
NAM/GFS continue to show a weaker system and keep any precipitation
south of the area, more along the track across AR into the TN
Valley. The ECWMF while showing some southward shift, continues to
have a bit stronger solution and generates some light precipitation
across southern MO including the far southern CWA, primarily late
Tuesday night.  Heading into the later part of the week, both the
GFS and ECMWF are now slower with the late week cold fropa associated
with the deepening and eventually progressive positively tilted
western upper trof as it phases with the northern stream. Both
models keep the front west of the CWA through mid evening on
Thursday, and then vary slightly on the orientation and speed of
the front into and through the CWA late Thursday night into Friday
morning. The slower solutions and later arrival of deeper cold
air now suggest that there may be little to no wintry post-frontal
precipitation.

The increasing trend of the ECMWF and GFS towards a highly amplified
pattern over NOAM and dominance of a deep broad upper trof by the
end of the week into early next week suggest: 1) we could be in
store for some very cold air, well below normal and 2) any snow will
be light and associated with disturbances rotating within the
cyclonic upper flow of the trof. This is very far off in the
forecast and it will be something to monitor in the days ahead.

Glass

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 524 AM CST Sun Dec 17 2017

Light rain will move through the terminals this morning. Ceilings
and visibilities will be low VFR or MVFR initially. Then MVFR
ceilings are expected to move into the area the rest of the
period. Some light drizzle and fog may develop between 06-15Z
which may also reduce visibilities into the MVFR range. Winds will
generally stay light out of the southwest through the period.

SPECIFICS FOR KSTL:

Light rain will move into the terminals by 15Z and end by early
afternoon. Ceilings with the rain will fall into the low VFR
range this morning, but then become MVFR the rest of the period
starting this afternoon. Some light drizzle and fog may develop
between 06-15Z which may also reduce visibilities into the MVFR
range. Winds will generally stay light out of the southwest
through the period.

Britt

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     48  43  57  43 /  70  20  20   5
Quincy          46  40  52  38 /  70  20  20   0
Columbia        48  41  55  42 /  70  20  20   5
Jefferson City  49  41  56  42 /  80  20  20   5
Salem           46  41  54  42 /  70  20  20   5
Farmington      44  40  56  43 /  80  20  20   5

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



Office: SGF FXUS63 KSGF 171130 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 530 AM CST Sun Dec 17 2017 .SHORT TERM...(Today and tonight) Issued at 134 AM CST Sun Dec 17 2017 A broad area of light rain was moving into the Ozarks and is expected to continue through this morning. The rain will end from southwest to northeast as we head into the afternoons hours, leaving behind cloudy skies for the remainder of the day. Most locations should see from 0.10" to 0.25" of rain with a lucky few seeing a bit more. The cloud cover will work to keep temperatures from climbing out of the 40s for most locations today but will also help to keep temperatures in the 40s overnight. .LONG TERM...(Monday through Saturday) Issued at 134 AM CST Sun Dec 17 2017 Southwesterly flow aloft will continue to start the week with mild temperatures Monday and Tuesday. An upper level low, now over Baja California, will makes its way east into the Texas panhandle and then across northern Texas into Tuesday. A surface low will develop and aid in brining some more Gulf moisture northward. Though the surface low will track east, it is forecast to stay south of the Ozarks with only the potential for some light precipitation making its way only as far north as the Missouri and Arkansas line. Some locations along the state line may see some very light measurable precipitation. An location north will likely only see a few sprinkles. The mild weather will continue through Thursday as semi zonal flow occurs behind the system late Tuesday night. A cold front will then begin to approach the region Thursday evening into early Friday morning. This system will bring another shot at some very light precipitation but more importantly will bring a colder and much more winter like air mass to the Ozarks. Behind the front on Friday, day time temperatures will struggle to make it to 40 degrees for all but the eastern Ozarks as the front moves slowly east. By the weekend afternoon highs will be in the 30s for nearly all locations with some areas across south central Missouri that may approach near the 40 degree mark. Models have been hinting at precipitation for Sunday, Christmas Eve Day, but there are significant issues with the coverage, timing and track of what appears to be a weak system. Will continue to watch the trend for now. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 525 AM CST Sun Dec 17 2017 Low clouds and rain across the region was helping to bring MVFR to IFR visibilities and ceilings the the areas terminals this morning. While the rain is expected to taper off by early afternoon, low, IFR cloud covering will linger through the remainder of the day and through the overnight hours. Expect flight conditions to remain IFR with a slow improvement to MVFR after sunrise on Monday. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...Hatch LONG TERM...Hatch AVIATION...Hatch
Office: EAX FXUS63 KEAX 171138 AFDEAX AREA FORECAST DISCUSSION National Weather Service Kansas City/Pleasant Hill MO 538 AM CST Sun Dec 17 2017 .Discussion... Issued at 335 AM CST SUN DEC 17 2017 The rain forecast for this morning is currently seen on radar sweeping it's way northeast along with the parent shortwave trough that is responsible for it. Currently, satellite and radar trends indicate that the system is moving rather quickly, and wont have much residency time in Kansas and Missouri today. Add to that the prevailing dry airmass that the trough has spread the rain across, and expectations for rainfall totals of a few hundredths to a couple tenth of an inch still look reasonable, with the highest amounts likely across in central to eastern Missouri. Otherwise, with generally light southerly winds persisting through the day, expect temperatures to remain a bit above normal despite the clouds cover and rain, with highs in the upper 40s to around 50. Looking beyond today, the prevailing pattern will continue to be dominated by a split flow through mid-work week as a western CONUS trough digs in across northern Mexico and turns into a cut off circulation, only to eject across the southern Plains later this week. Precipitation from the transit of the trough across the southern Plains wont reach as far north as our section of Kansas or Missouri. Temperatures will continue to run above normal as the prevailing westerlies from the split flow remain to our north, keeping the truly cold winter air trapped up north for a few more day, though that will change by the end of the work week. Of interest later in the work week will be a large scale adjustment in the pattern as the split flow across the western CONUS, that has been dominating for the past couple of weeks, will finally evolve into a large trough, resulting in a highly amplified pattern in place across the Nation by next weekend. This may result in a bit of light rain to snow across the northern portion of Kansas and Missouri Thursday as the developing trough ejects a leading shortwave across the northern Plains, which will result the focus for precipitation residing to our north. But, regardless of what precipitation falls, temperatures for Friday and through the holiday weekend will be chilly, with highs in the 30s and lows well down into the 20s, and maybe teens. && .Aviation...(For the 12Z TAFS through 12Z Monday Morning) Issued at 537 AM CST SUN DEC 17 2017 VFR CIGs have moved in across the region early this morning along with some light rain showers.IFR CIGs are expected to make a brief appearance later this morning as the system moves northeast. IFR CIGs should lift this afternoon into the MVFR range, but confidence on when and how high CIGs lift is a bit low. Otherwise, expect light winds to prevail form the south to southwest. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...Cutter Aviation...Cutter