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Office: LSX

FXUS63 KLSX 170825
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
325 AM CDT Wed Aug 17 2022

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 322 AM CDT Wed Aug 17 2022

Early morning fog will be an issue for some areas today, mainly
in/around river valleys. The GOES-16 Nighttime microphysics RGB
shows the fog well, with the most concentrated and densest fog
along the Missouri River and its tributaries in parts of central
and east-central Missouri. Any fog should quickly evaporate this
morning due to the strong mid August sunshine. Other than
few/scattered diurnal cumulus later today, plenty of sunshine
should be expected across the area as high temperatures reach into
the low to mid 80s.

A mostly clear night is on tap tonight, along with light/variable
winds as a weak surface ridge remains anchored over the mid-
Mississippi Valley. These conditions are favorable for radiational
cooling, so leaned toward the 25th percentile of available model
guidance for forecast low temperatures. This resulted in readings
bottoming out in the upper 50s to low 60s across the area, or
about 5-7 degrees below normal for the date. Some more fog
development is also expected, generally confined to river valleys.

Persistence is the key word for Thursday as there is very little
change in the atmosphere. Highs should be a couple of degrees warmer
compared to this afternoon however as the air mass modifies.


Gosselin


.LONG TERM...  (Thursday Night through Tuesday)
Issued at 322 AM CDT Wed Aug 17 2022

A pattern change begins to occur Thursday night as the stubborn
surface ridge of high pressure slides into the Ohio Valley and a
more active northwest flow regime begins aloft. A midlevel shortwave
trough is expected to move across northern sections of the area
Thursday night. However, this feature should only bring an increase
in mid/high level cloud cover as moisture return is lacking and the
timing of its passage (at night) occurs when there is little/no
instability. Due to the aforementioned clouds, low temperatures are
likely to be about 2-4 degrees warmer compared to tonight's values
but still slightly below normal for this time of year.

WPC cluster analyses of the 500-hPa height pattern show very little
differences Friday through Sunday with the evolution of the next
shortwave trough. Ensemble members generally agree that this feature
will close off over the Upper Midwest on Friday. As it gets more
cutoff from the mean flow north of the US-Canadian border, its
progress eastward is likely to slow. Differences with the closed low
increase by early next week as some guidance (including a majority
of EPS members) stall it over the lower Ohio Valley while other
ensemble guidance continues a slow, but steady eastward movement
toward the northeast. In terms of sensible weather impacts, this
closed low should bring at least scattered showers and thunderstorms
to the bi-state area beginning late Friday. Precipitation chances
likely will be heavily influenced by diurnal instability, so expect
the best chances in the late afternoon hours, with activity likely
diminishing by the late evening. Precipitation chances by early
next week likely should decrease at least somewhat, though they
may linger in southern and eastern sections of the area if the
ECMWF/EPS solution where the closed low stalls in the lower Ohio
Valley verifies. Chances of showers and thunderstorms and
associated cloud cover will also help drive temperatures. During
the day, highs should stay slightly below normal and mainly in the
low to mid 80s through the period. Nighttime lows are expected to
be closer to climatological normals, or in the low to mid 60s.


Gosselin


&&

.AVIATION...  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1000 PM CDT Tue Aug 16 2022

Skies continue to gradually clear and local terminals late Tuesday
evening, with widespread VFR conditions observed at this writing.
Overnight through early tomorrow morning, some patchy fog may
develop in limited areas, and in particular across river valleys
and other low lying areas. A few terminals may see intermittent
visibility reductions late tonight and early Wednesday morning as
a result. Confidence is low regarding which areas will see direct
impacts, but terminals like SUS, JEF, COU, and CPS are among the
more likely places to see at least some fog development.

Otherwise, VFR conditions are expected the remainder of the 06Z
TAF cycle. A scattered to broken cumulus field is expected to
develop during the afternoon tomorrow, but ceilings will likely
remain above VFR levels.

BRC

&&

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

$$

WFO LSX



Office: SGF FXUS63 KSGF 170756 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 256 AM CDT Wed Aug 17 2022 Key Messages: 1. Lingering showers to fade this morning over southern Missouri. 2. Cooler temperatures overspread the area the next several days. 3. Additional rain chances this weekend into next week. .SHORT TERM...(Today through Friday) A surface low pressure center over Oklahoma in conjunction with an approaching upper level shortwave disturbance forced convection across southern Missouri overnight. This activity is expected to eventually fade south of the region throughout the morning hours, bringing dry and cool conditions to all areas by late morning and through the afternoon hours. Temperatures today may struggle to warm out of the 70s in many areas. Locations along and north of the Highway 54 corridor may warm into the low 80s with more sunshine up north. Weak northwest flow aloft will keep temperatures on the cool side through the rest of the work week and into the weekend. Conditions are also likely to remain dry through at least Friday, with highs reaching the 80s both Thursday and Friday afternoons. Overnight lows will drop into the 60s. .LONG TERM...(Saturday through Tuesday) The summertime high that is typical of August remains non-existent this upcoming weekend and into early next week. Several operational and ensembles models suggest that a closed off upper low will drop out of Canada within an overall northwest flow regime. This system will help draw moisture back into the Ozarks, setting the stage for another round of widespread rainfall Saturday into Sunday. The NBM has some pretty hefty rainfall totals advertised across southern Missouri during the Saturday and Sunday time frame. We will need to monitor potential amounts with later forecasts to see if there is some consistency. There remains a lot of uncertainty with the forecast for Monday into Tuesday. Several models suggest that showers and thunderstorms will be numerous while other solutions dry us out. The NBM continues precip chances both Monday and Tuesday. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1203 AM CDT Wed Aug 17 2022 Ceilings and vis have been bouncing around between IFR up to VFR as precip moves through. Lower conditions have been occuring within the storms then increasing back to VFR behind storms. Highest chances for IFR and showers and storms are at JLN and BBG tonight. Amendments are likely overnight as conditions change quickly. Winds will remain out of the east to northeast with ceilings increasing to MVFR by late Wednesday morning. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...Cramer LONG TERM...Cramer AVIATION...Burchfield
Office: EAX FXUS63 KEAX 170853 AFDEAX AREA FORECAST DISCUSSION National Weather Service Kansas City/Pleasant Hill MO 353 AM CDT Wed Aug 17 2022 .Discussion... Issued at 352 AM CDT WED AUG 17 2022 Key Points: * Pleasant summer day today and tomorrow. * Slow moving disturbance building into Iowa will create a chance of storms late Friday into the weekend. Detailed discussion... Fairly slowly evolving large scale pattern across the US with an upper level trough across the upper NE and large scale ridge across the west. This is leading to northwest flow aloft across the central US. Visibility at observation sites across central Missouri have been fluttering around in the pre-dawn hours. Expect mid and high clouds to prevent widespread fog from developing this morning. Any fog that develops is expected to be fairly localized and should quickly burn off after sunrise. Looking at a pleasant late summer day today with fair weather cumulus developing throughout the day. Temperatures are expected to remain below normal with easterly winds prevailing and 850 HPA temperatures ~12-13 C. Similar conditions expected on Thursday as intensifying short wave moves from central Canada into the Upper Midwest. This wave is expected to move into Iowa on Friday, with the associated cold front building south on Friday. Ahead of the front, surface based CAPE values are expected to rise to 1000-1500 J/kg, and mid level wind shear is expected to increase. 0-6 km bulk shear is in the 30- 40 knots, strong enough that a few storms Friday afternoon into Friday evening may be strong. SPC has outlined portions of NW Missouri in a marginal outlook for severe weather. Upper level low across Iowa is a slow mover and is only expected to move into the western Great Lakes by Sunday. With the low in the neighborhood, could see some diurnally driven showers and thunderstorms through the weekend with greatest chances across northern Missouri closer to the upper level low. As the disturbance works eastward, the chance of precipitation is expected to decrease late weekend into early next week with near- slightly below seasonal temperatures. && .Aviation...(For the 06Z TAFS through 06Z Wednesday Night) Issued at 1110 PM CDT TUE AUG 16 2022 Light visibility restrictions already being observed across the area, so with mid level clouds in place it's slightly uncertain just how low the visibility will get overnight. With recent rains and cool air moving in confidence is medium that there will be at least some brief reduced visibility through the sunrise hours. Thereafter VFR will prevail through the day. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...BT Aviation...Leighton