083 
FXUS64 KFWD 090012
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
612 PM CST Thu Feb 8 2018


.AVIATION...
VFR through this evening with scattered to broken high clouds. Low
level moisture will increase overnight with the development of a 
30 knot low level jet. MVFR ceilings (between 2000 and 3000 ft) 
will return to Waco overnight and reach the Metroplex TAF sites 
just after sunrise Friday. Ceilings will lift through the morning
and become VFR between 4000 ft and 5000 ft Friday afternoon and 
evening. MVFR ceilings will return to all TAF sites late Friday 
evening.

A light east to southeast wind this evening will turn to the 
south overnight remain southerly on Friday. Wind speeds will 
increase after sunrise Friday between 10 and 15 knots along with 
some higher gusts, especially in the afternoon.

79

&&


.SHORT TERM... /Issued 259 PM CST Thu Feb 8 2018/
/Tonight/

Surface high pressure has shifted east of the forecast area, and 
weak return flow has begun across the northern half of the 
region this afternoon. The southern half will follow suit this
evening as the ridge axis shuffles farther east towards the Mid
Atlantic states. Low level flow will be on the increase tonight, 
and the resulting moisture return will lead to increasing low 
clouds across the eastern half of the region Friday morning. 
Higher dewpoints and southerly winds will keep temperatures above
last night's readings, with lows ranging from the mid 30s along 
the Red River to the mid and upper 40s across the southern 
counties.

30

&&

.LONG TERM... /Issued 259 PM CST Thu Feb 8 2018/
/Friday through Wednesday/

A strong arctic cold front will be moving south across the 
Central Plains Friday in response to a mid level vort max moving 
east out of the Central Rockies. In advance of the cold front, 
falling pressure along the immediate lee of the NM/CO Front Range 
will allow for gusty south surface winds 15-20 mph and increasing 
moisture moving up from the Gulf of Mexico as 50s dew point 
temperatures return to the area. Some morning low clouds will 
encompass the southeast half of the region with a few afternoon 
showers across this same area. Most of the richest moisture will 
remain east of U.S. 281 from Jacksboro-Hamilton, so areas along 
and west of this area will see warm, breezy, and dry conditions 
that could result in an elevated fire danger Friday afternoon. 


Friday night will see the arrival of a southern stream vort max 
which will continue to enhance the low level warm advection ahead 
of the approaching arctic cold front. Column moisture will 
continue to deepen especially across areas east of I-35 overnight.
The lift will help to moisten and eliminate the elevated 
inversion aloft with some skinny CAPE increasing across Central 
Texas. Chances of showers and possibly a few isolated, non- severe
thunderstorms are expected across mainly the eastern half of the 
CWA. That said, precipitable water values do not appear to be very
high, so rainfall amounts will average on the light side and 
below an inch in the east, with lesser amounts as you progress 
west toward the I-35 corridor. 

Meanwhile, the leading edge of the shallow arctic air will 
approach our northwest counties around daybreak Saturday morning. 
The higher resolution models such as the NAM, WRF, SPC HREF, 
Euro, and Canadian(GEM) appear to handle this very shallow airmass
the best versus the GFS due to resolution. The GFS is still 
struggling with such airmasses that begin in the sub-boundary 
layer. Similar to the overnight forecast, we have blended a Euro, 
GEM, NAM with the arctic cold front. Regardless, the far northwest
counties could see lows drop quickly into the 30s during the pre-
dawn hours, with the remainder of the pre-frontal CWA remaining 
in the mid 40s to mid 50s. Some patches of light drizzle and even 
light fog can't be ruled out in the warmer and moist airmass ahead
of the cold front late Friday night. 

This weekend becomes somewhat complicated, at least with 
precipitation timing and potential, while there's no doubt about 
the chilly airmass coming down. Ahead of the cold front, many 
areas will see highs occur in the mid-late morning, possibly early
afternoon before temperatures rapidly tank the remainder of the 
day. Patchy drizzle and possibly some light fog will continue 
during the morning hours in advance of the arctic cold front. 
Meanwhile, the aforementioned southern stream vort max will be 
tracking east over Central and Southeast Texas through the day 

with lingering chances of showers and a few isolated 
thunderstorms, especially south of I-20/30 through much of the 
day. The cold front is expected to have easily cleared our area by
Saturday night, as we have a brief lull in activity Saturday 
evening. 

However, a much stronger vort max will be trailing and moving 
southeast across the Four Corners region and Central/Southern High
Plains during the overnight hours. Increasing pressure advection 
(ie...lift) will be punching into the Hill Country and Permian 
Basin areas on the 300K-310K surfaces with some weak instability 
aloft. Though 25-30 knot flow appears parallel with little in the 
way of isentropic upglide, the pressure advection itself will 
likely result in some overrunning, light precipitation across 
mostly Central Texas. That said, weaker overrunning is possible 
further north and west. Low chances of a light freezing drizzle 
or very light rain may occur across areas northwest of a Cooper, 
to Coriscana, to Gatesville and Lampasas line. 

The positive-tilted strong vort max looks to exist east across 
KS/OK during the day Sunday, so bulk of the better forcing will 
remain north of the better moisture and within the deeper and 
drier arctic air to our north. As such, we "may" see a mix of 
light freezing drizzle, freezing rain, or drizzle along a corridor
from Sulphur Springs to Hillsboro, to Lampasas/Killeen briefly 
Sunday morning before temperatures warm to above freezing. Further
south a cold rain is expected. Low chances for a a light cold 
rain will linger over Central Texas Sunday afternoon with highs
struggling to reach the lower-mid 40s. Confidence is high on the 
shallow arctic air and very cold temperatures, but low on the 
evolution of moisture, lift, and any overrunning for light 
precipitation before the deeper and dry arctic air arrives on 
Sunday. Any light precipitation should end across our eastern 
counties sometime Sunday evening and while temperatures remain 
above freezing. By Monday morning, all the forcing from this 
system will have moved off to the northeast with a very chilly 
start to the day. Highs Monday will struggle to get into the 
lower to mid 50s. 

The shallow arctic cold air looks to shift to the east by Tuesday
and moving into the mid week period, as an organizing mid level 
trough across the Northern Rockies and Great Basin helps induce 
lee cyclogenesis and the return of southerly flow across the 
Plains and our area. Both temperatures and modified Gulf moisture
return with highs warming back into the 60s with overnight lows 
generally in the 40s and 50s. The resultant low level warm 
advection will likely result in some low rain chances across 
mainly the eastern half of the region once again, while the 
western areas are left out once again. 

05/

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    40  69  50  50  29 /   0   0  20  20  20 
Waco                43  70  54  55  33 /   0   0  20  20  30 
Paris               38  61  50  50  29 /   0   0  40  40  30 
Denton              37  69  44  44  26 /   0   0  10  20  10 
McKinney            38  66  50  50  28 /   0   0  20  20  20 
Dallas              41  70  52  52  30 /   0   0  20  20  20 
Terrell             39  66  52  53  29 /   0   0  30  30  20 
Corsicana           44  67  54  55  32 /   0   0  30  30  30 
Temple              44  69  53  55  33 /   0   0  20  20  30 
Mineral Wells       35  74  41  41  24 /   0   0   5  10  10 

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

79/92