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

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FXUS63 KEAX 212013
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
313 PM CDT Thu Mar 21 2024

.KEY MESSAGES...

- A cold front will move through the region tomorrow, with best
  chances (30 to 50 percent) of showers in far northern and
  northeast Missouri.

- Freezing temperatures are highly probable (greater than 90
  percent chance) Friday night across the entire region.

- Periods of showers and storms are expected Sunday and Monday.
  Severe weather is not expected. Breezy to windy conditions
  are expected, however.

- Much cooler weather is expected early next week, with more
  freezing temperatures across the region Monday and Tuesday
  nights.

&&

.DISCUSSION...
Issued at 218 PM CDT Thu Mar 21 2024

The 12z upper-air objective analysis indicates general split
flow in much of the U.S. today, with a low-amplitude southern-
stream trough ejecting from the southern Rockies and a long
fetch of northwesterly flow from the Upper Midwest to the Mid-
Atlantic. As expected, temperatures this afternoon varied by a
decent amount from the northeast to the southwest CWA (upper 40s
to lower 60s), with a stiff easterly breeze keeping a decent
chill in the air. However, increasingly southerly/southeasterly
low-level flow in advance of the aforementioned trough has led
to substantial warm/moist advection across southern portions of
the region this afternoon (i.e., surface dew points increasing
by around 20 degrees in the last 12 hours). This should mitigate
substantial cooling overnight, with southerly flow preventing
full decoupling and keeping minimum temperatures well above
freezing.

A weak but gradually amplifying/digging trough in the northern
stream will progress rapidly southeastward tonight, reaching the
Upper Midwest by morning. An attendant cold front will move
quickly southeastward through northern and central Missouri on
Friday. Though moisture return will be persistent in advance of
the front, the antecedent very dry environment will prove
formidable to develop widespread precipitation along the front
farther south displaced from the stronger large-scale ascent in
the northern Plains and Upper Midwest. Thus, chances for showers
and isolated storms remain muted in our region (generally 30 to
50 percent in far northern Missouri; less than 30 percent south
of U.S. Highway 36). Thermodynamic and kinematic profiles are
not favorable for any severe weather. Timing of the highest
precipitation chances is generally between sunrise and early
afternoon, with the front through the CWA entirely by 21z.

Perhaps the more substantive impacts with the front will be the
breezy north/northwest winds and the sharply colder
temperatures. By afternoon, wind speeds of 15 to 25 mph with
gusts up to 35 mph will be common across the region. Rising
temperatures will slow to a crawl after frontal passage and may
actually fall gradually during the afternoon. As winds diminish
quickly Friday night and skies clear in the wake of the system,
temperatures will crash to well below freezing by Saturday
morning. We will assess the need for freeze products Friday
night and Saturday morning in later forecast updates, but we
strongly recommend protecting vulnerable vegetation tomorrow
night.

Brief ridging will progress into and through the central U.S.
this weekend in advance of a deep trough entering the
Intermountain West. This will result in a substantial surface
cyclone developing in the lee of the Rockies by Sunday morning.
Temperatures will remain cool on Saturday but should trend
warmer Saturday night and Sunday as considerable warm/moist
advection in advance of the large-scale trough commences. This
will lead to widespread precipitation in the central U.S.
Sunday and Monday. Fortunately, temperatures will be warm enough
in our region for precipitation to be all liquid, with at least
marginal instability available for thunderstorms on Sunday and
Sunday night. Severe-weather chances look rather muted given
poor timing of the strongest lift and generally weak
instability. However, shear profiles look fairly decent in
advance of the cyclone, so if trends in the forecast lead to
more instability and more vigorous convection -- severe-weather
chances would increase. At this point, though, the precipitation
impacts of this system in our area look benign, with much-
needed rainfall the main result.

One thing worth watching with the developing system is winds on
Sunday and Monday. With ensemble means showing southerly 850-mb
winds of 45-60 kt in advance of the central-U.S. low, it will
not be difficult to mix down these winds to the surface.
Advisory-level winds could be realized on Sunday and/or Monday,
especially in far western/southwestern portions of the CWA on
Sunday (probabilities greater than 40 percent exceeding
advisory criteria).

Another round of stout cold advection in the wake of the
synoptic cold front will occur by Monday afternoon/evening, with
a period of below-seasonal temperatures through midweek.
Multiple nights of freezing temperatures are expected in this
pattern. As has been the case early this year, recovery from
cold weather should be reasonably fast, with ensembles showing
temperatures above average again by week`s end.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1221 PM CDT Thu Mar 21 2024

East winds will continue around 10 kt this afternoon with
occasional gusts to 20 kt, with SCT/BKN CIGs around 5-6 kft this
afternoon before dissipating this evening. Winds will diminish
overnight as they veer gradually to the south and then will veer
quickly Friday morning as a cold front moves through the
region, becoming northwesterly and gusty by midday. Cloud cover
will increase late tonight with bases lowering quickly as the
front moves through on Friday. MVFR CIGs appear likely (>70
percent chance) for a few hours late in the morning into the
afternoon.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

DISCUSSION...CMS
AVIATION...CMS


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