Area Forecast Discussion
Issued by NWS Tulsa, OK

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FXUS64 KTSA 171740
AFDTSA

Area Forecast Discussion
National Weather Service Tulsa OK
1140 AM CST Sun Dec 17 2017

.DISCUSSION...

The discussion for the 18Z TAF forecast is included below.

&&

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
A cool and saturated boundary layer, left behind from a storm
system that brought rain last night, will result in poor
conditions for aircraft ops thru much of the forecast. Most sites
are IFR currently, but some improvement to MVFR is expected later
today. Most areas, however, should descend back into the IFR or
blo category again tonight. The latest data from the NAM and RAP
suggest that low stratus will hang on thru the day and into
tonight, before eroding Monday morning, as the boundary layer
warms and dries out from westerly flow. The GFS had this process
occurring faster, as soon as this evening, but this solution was
discounted. Low clouds that hang on thru the day typically don`t
just vanish as we go into the night. IF there are areas where this
does actually occur, however, sub-IFR dense fog would likely be
the result. So one way or another, expect poor conditions for
aviation thru tonight. All sites should return to VFR by mid-
morning Monday as the Sun heats the boundary layer and burns the
low clouds/fog off.

Lacy

&&

.PREV DISCUSSION... /Issued 955 AM CST Sun Dec 17 2017/

DISCUSSION...

The upper wave that brought last night`s welcome rains has already
lifted up into IA/IL this morning. While the rains have ended, a
cool and saturated boundary layer remains, beneath a stout
inversion. Some weak lift is evident in short term hi-res model
guidance in this saturated boundary layer, which explains the
pockets of drizzle on area radars. Expect this to continue thru
around midday or so. Cigs will gradually rise this afternoon as
well. Eventually, the low level flow will veer to more of a
westerly direction, warming and drying the bulk of this low level
moist layer, but it is highly uncertain how quickly this will
occur. Will thus elect to keep skies cloudy thru the day and have
adjusted hi temps slightly downward. Updated text products sent.

Lacy

PREV DISCUSSION... /Issued 447 AM CST Sun Dec 17 2017/

.UPDATE...

AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.

Low ceilings and IFR to MVFR conditions are expected to prevail
through the period at all the terminals, although cloud bases will
likely lift some during the afternoon before lowering again in
the evening. Although it is not currently forecast, the chance is
not zero that the low clouds could erode late afternoon and into
the evening from the southwest as moisture aloft diminishes, and
if this occurs, fog would likely develop.

PREV DISCUSSION... /Issued 345 AM CST Sun Dec 17 2017/

DISCUSSION...
Rain is on its way out, and should be totally gone within the next
couple hours, so will keep a dry forecast for today. Clouds will
remain stubborn though, which will hold high temperatures to the
50s.

Mild to warm weather will be the rule from Monday through
Thursday, with temperatures running 10 to 20 degrees above normal
for the most part each day. An upper level storm system will track
near the Red River Tuesday night bringing widespread rain to the
southern part of the forecast area, with rain chances tappering
off to the north.

The much anticipated strong cold front will drop south across the
area late Thursday or Thursday night, with much colder air
following in its wake. The true arctic air will arrive Christmas
Eve or Christmas Day, and may be accompanied by some light wintry
precipitation. At this time, significant wintry precipitation
appears quite unlikely for the time period around Christmas.

Stayed close to the warmer GFS/ECMWF MOS temperatures the next
couple days.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   53  37  63  48 /  10  10   0  10
FSM   55  39  65  49 /  10  10   0  10
MLC   55  37  64  51 /  10   0  10  10
BVO   52  33  62  43 /  10  10   0  10
FYV   52  37  61  46 /  10  10   0  10
BYV   52  38  61  48 /  10  10   0  10
MKO   54  38  63  49 /  10  10   0  10
MIO   52  38  60  47 /  10  10   0  10
F10   54  37  64  49 /  10  10   0  10
HHW   56  39  64  52 /  10   0  10  10

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&

$$

AVIATION.....30



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