Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 250930

430 AM CDT Wed Mar 25 2015

Issued at 315 AM CDT WED MAR 25 2015

Currently - This Morning:

Low stratus/fog has been overtaking much of the forecast area with
the lowest ceilings and worst visby conditions across portions of
northern MO, coincident with where yesterday`s rains fell.
Conditions should continue to deteriorate over the next few hours
before mixing sets in after sunrise this morning. Temperatures
are expected to remain just above freezing through the morning
across the north so freezing fog shouldn`t be an issue. Otherwise,
look for a benign start to the day before activity reignites later
this afternoon.

Midday Today - Overnight:

Showers and thunderstorms will once again develop this afternoon
out ahead of another low pressure system grazing past southern MO
later tonight and an upper trough swinging through from the NW. There
will be two different areas of precip setting up with slightly
different forcing as a result. Across northern MO and adjoining
state boundaries, confluence aloft and lower-level frontogenesis
will provide the forcing that showers and isolated (elevated)
thunderstorms need, along with PWATs increasing throughout the
day. In the south (central MO), development is associated with the
low passing through as moisture and instability get advected in
with it. The better instability should remain south of this
forecast area this evening through tonight but if any of that can
get pulled into the southern counties, could see some storms
becoming strong as the better dynamics lays out across this
forecast area. Severe threat looks to be lower for this evening as
compared to last evening, especially if storms take a while to
fire up, losing the diurnal heating factor as the evening
progresses. However, cannot entirely rule out a misbehaving storm
or two with hail, followed by winds, being the primary threats
once more. Have leaned on hi-res models for this forecast update,
given how well many of them performed last night.

Temperatures will struggle to get out of the 50s north of the I-70
corridor today with lower 50s expected near the NE/IA/MO borders.
Highs could reach into the upper 60s in the far southern counties,
where the aforementioned strong storm threat exists.

Thursday - Friday Night:

Much quieter conditions settle back into the region at this point
with just some light precip traversing through overnight Thursday
into early Friday and then again possibly overnight Friday. This
is on the backside of the previously mentioned upper trough that
will have swung through, with a vort max rotating through, as well
as being situated on the left exit region of a meridional upper
jet as the driving forces. High temps on Thursday will only reach
the 40s and 50s, and as the chillier air settles in by Thursday
night, lows will drop into the 20s and lower 30s. As such, along
with a vertical thermal profile supportive of ice growth within
the cloud layers, could see light rain (ice pellets?) either
mixing in with light snow or the light snow as the dominate precip
type as the temps drop throughout the night. However, no
accumulations are expected, especially given how warm the ground
surfaces have been as of late.

Friday`s highs will be even cooler than Thursday, ranging from the
lower 40s to near 50 from NE MO to the KS/MO border, respectively.
Friday night lows will again drop off into the 20s and 30s,
although currently looks to be slightly warmer than Thursday night
as the colder airmass begins to pull away from the region. Another
opportunity for rain and/or light wintry mix could greet the
forecast area again Friday night as little changes to the overall
pattern occur. While some of the models sort of agree on precip
occurring that night, the key word is "some" as there are
disagreements on whether or not this secondary "round," so to
speak, will play out. Should have a better idea as this time
period gets closer, allowing for a higher confidence forecast.
Regardless, any precip should be light once again, with no
accumulations expected if wintry precip does fall.

Saturday - Tuesday Night:

As alluded to just above, the 00Z GFS and ECMWF diverge on
solutions for the weekend through early next week. They both
indicate a frontal boundary passage later in the weekend on
Sunday, but disagree spatially and temporally on the parent low
trekking across the Canadian-U.S. border and through the upper
Great Lakes. Have left slight chance PoPs in for the eastern third
of the forecast area on Sunday but stay tuned to future updates
as the details get worked out. By early next week, the surface
pattern diverges even more extensively, likely being translated
down from subtle but obvious differences in the depiction of the
upper-level pattern. Therefore, low confidence forecast with
respect to precip that far out at this juncture.

Where higher confidence forecasting exists is in the temperatures
through this time frame. Warm-up begins on Saturday with highs
looking to reach well into the 60s area-wide. Sixties to lower 70s
appear to continue through next week with relatively seasonal
lows in the 30s and 40s, with potentially some 50s as lows by the
end of this forecast period.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1205 AM CDT WED MAR 25 2015

IFR/MVFR CIGs widespread across the area will likely hold on for the
remainder of the night, and into the early hours. Most sites are
between OVC006 and OVC010, so there could be some rising and lowering
of CIG`s throughout the night. Guidance suggests off and on fog at
the terminals, especially KSTJ and KMCI, so introduced an early
morning TEMPO for MVFR VIS. Light rain then moves northward tomorrow
evening, which would possibly bring some visibility restrictions. For
now the concern for thunderstorms is small at the terminals, but will
be watching for convective storms after 00z.




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