Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KLSX 222346

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
646 PM CDT Sat Oct 22 2016

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 343 PM CDT Sat Oct 22 2016

High pressure at the SFC and aloft will combine to produce quiet wx
thru the end of the wknd. SFC ridge will remain centered over the
Lower MS Rvr Vly and SE US thru Sun which will keep sthrly flow
going. A short wave is fcst to top the ridge tonight and then pass
to the N/NE of the region tomorrow. An 30-40KT E-W LLJ is expected
to dvlp tonight across MO and into sthrn IL. There is decent WAA and
850 moisture convergence overnight in assoc with this feature but a
very dry atmosphere limits expected cloud cover let alone
mentionable PoPs. The short wave will drag a cold front thru the
area Sun aftn. Due to the bone dry atmosphere...FROPA is expected to
be dry.

Temps tonight should not be as cool as last night since the SFC
ridge axis will have shifted to the SE and winds will remain around
5 kts overnight. High temps tomorrow will also have a chance to
moderate about 5 degrees from today`s high temps due to the
sustained sthrly flow that is expected to become SW/WSW thru the day
and full sunshine. Temps are expected to be some 5-10 degrees above
average thru the remainder of the wknd.


.LONG TERM...  (Sunday Night through Next Saturday)
Issued at 343 PM CDT Sat Oct 22 2016

The effective cold front should be up across northern Missouri
stretching into northwest Illinois.  The front will push south
overnight and should be through the CWFA down to near the
Missouri/Arkansas-Kentucky/Tennessee border by sunrise on Monday.  A
ridge of high pressure stuck over the Gulf Coast will block any
decent moisture return ahead of the front, so the FROPA still looks
dry.  The low level thermal gradient behind the front looks like it
will set up from Columbia northeast across the Mississippi River
with warmest readings out in central and southwest Missouri.  For
most of our CWFA , this should be another little shot of Fall
with temperatures falling back to near or a few degrees below
normal. Much of central and southern Missouri will probably remain
a few degrees warmer though.

The surface ridge behind the front will build across the eastern 1/3
of the CONUS and south-southeast flow will prevail through Tuesday
night ahead of the next shortwave.  With the aforementioned thermal
gradient still in place, expect warmest temperatures to continue to
be across central Missouri on Tuesday with highs 3-5 degrees above
normal.  The next shortwave in line dips into the Great Plains
Tuesday afternoon/evening time frame.  This wave is stronger than
the one coming through Sunday night and between the stronger
synoptic forcing and a bit more moisture return ahead of the front,
we should see some precipitation.  Forecast instability shows as
much as 350-900 J/kg of MUCAPE ahead of the front so thunderstorms
still look like a good forecast Wednesday into Wednesday evening.
Looks like there may be some trailing precip behind the front, but
PoPs do drop off quickly after FROPA after 06Z Thursday.

Remainder of the medium range looks quiet with temperatures near or
a few degrees above normal.  Guidance has another cold front moving
into the area next Saturday or Sunday, but there`s little agreement
between medium range models for timing so am sticking with a dry and
relatively warm forecast on for next Saturday.



.AVIATION...  (For the 00z TAFs through 00z Sunday Evening)
Issued at 645 PM CDT Sat Oct 22 2016

VFR conditions are expected through the period. Surface high
pressure continues to slide off to the southeast this evening as
an area of low pressure moves across the Northern Plains. This
regime will help induce a low-level jet tonight into early Sunday
morning, bringing a period of LLWS to all sites overnight.
Otherwise, Sunday will feature southwesterly winds with gusts to
around 15-20 knots, turning more to the WNW by the end of the
period as a dry cold front moves through all sites.

VFR conditions are expected through the period. Winds will
increase out of the WSW just off the surface tonight, which will
lead to a period of marginal LLWS late tonight into early Sunday
morning. Surface winds will increase out of the WSW by Sunday
afternoon, which could cause some crosswind impacts on the three
larger runways. Otherwise, a dry cold front will push through
Sunday evening, turning winds more out of the WNW.



Saint Louis     55  79  50  67 /   0   0   0   0
Quincy          51  74  46  64 /   0   0   0   0
Columbia        51  75  47  67 /   0   0   0   0
Jefferson City  51  76  45  69 /   0   0   0   0
Salem           48  74  47  66 /   0   0   0   0
Farmington      50  75  48  68 /   0   0   0   0




WFO LSX is the U.S. government's official web portal to all federal, state and local government web resources and services.