Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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FXUS64 KFWD 212344 AAA

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
644 PM CDT Wed Mar 21 2018

/00Z TAFs/

VFR conditions will continue the next 24-30 hours. Occasional
altocumulus FL150-170 and cirrostratus FL250-300 can be expected
to stream southeast within northwest flow aloft over the area tonight
into Thursday.

A surface ridge over the Ozarks/Ark-La-Tex will continue to move
east away from the area with increasing southeast winds 10 knots
or less tonight, becoming southerly and gusty at 15-20 knots by
midday Thursday and beyond. No precipitation is expected.



.SHORT TERM... /Issued 344 PM CDT Wed Mar 21 2018/
/Tonight and Thursday/

Tonight will be quieter and warmer, and Thursday will be a breezy
and warm day across the region. The surface high is still moving
east of the region, but southeast winds have returned across
almost all of North and Central Texas. Wind speeds tonight will
continue at 5-15 mph, but will increase on Thursday. The skies
tonight are expected to remain mostly clear with some passing high
clouds, but we may see a small amount of low level stratus in our
southwestern counties near daybreak. Overnight lows will be
significantly warmer in the mid 40s to lower 50s.

Upper level ridging will strengthen across the region on
Thursday, and daytime temperatures are expected to climb into the
70s. Some locations will likely reach 80 degrees. Surface winds
will increase in response to a developing surface low to our
northwest, and wind speeds of 15-20 mph with gusts up to 25 mph
can be expected. These strengthening winds will start the
moisture return process that will continue into the weekend.
Passing high clouds will continue, but we will likely also see
fair-weather cumulus clouds develop during the afternoon hours.



.LONG TERM... /Issued 344 PM CDT Wed Mar 21 2018/
/Thursday Evening through Tuesday/

The predominant weather highlight in the extended will be the
chance for an prolonged period of showers and thunderstorms,
particularly during the latter half of the weekend and into next
week. Warm to even hot conditions will be possible this weekend
with more seasonable temperatures next week.

Thursday Evening into Friday morning will be mild and breezy as
southerly flow increases further. The added moisture (and thus
cloud cover) from the south winds in combination with the breezy
conditions should allow overnight lows to only fall into the 50s
and 60s areawide.

Friday will be a warm day, particularly across the Big Country where
high temperatures will climb into the upper 80s. Elsewhere, cloud
cover may hang tough resulting in limited insolation. It`ll still
remain warm under partly to mostly cloudy skies, however, and
high temperatures near and east of I-35 will climb into the 70s
and low 80s.

On Saturday, a potent upper low will slide eastward into the Ohio
River Valley and should be replaced by shortwave H5 ridging
aloft. While the H5 ridge should ensure that most of the area
remains mostly rain-free through the day on Saturday, a cold front
associated with the eastward moving upper low will slide
southward towards the Highway 380 corridor in North TX. Winds
will veer a bit with the approach of the cold front and this may
keep some of the richer Gulf of Mexico moisture south and east of
the area. With the veered flow ahead of the front, it`s likely
that temperatures will soar into the mid to upper 80s. Locations
across the eastern part of the Big Country may even climb above
90 degrees as favorable downslope winds should overspread the
region. The post-frontal air may quickly modify as a slight
westerly component to the winds will induce some compressional
warming and so even far northwest zones should still warm into the
80s. With the best isallobaric couplet shifting into the Missouri
River Valley, the front should slow and eventually stall
somewhere between the Highway 380 and I-20 corridor.

On Saturday afternoon a dryline will sharpen across the Big
Country, but at this time, the latest model guidance keeps this
feature to the west of our counties. While the cap does weaken
some, the lack of robust lift precludes any mention of widespread
rain/storms prior to 00 UTC Sunday. If this dryline mixes a bit
farther to the east, it`s possible that there may be a chance for
convective development along the dryline/frontal boundary
interface near and west of Highway 281. An eastward positioning
of the dryline into our counties isn`t supported by much of the
guidance, except the 12 UTC deterministic GFS and for now I feel
safe keeping much of Saturday rain/storm free. We will need to
monitor the position of the dryline, however, as the regime would
be supportive of strong to severe thunderstorms, should they

As the next upper trough moves towards the west coast, broad
southwest flow aloft should help to induce lee-side cyclogenesis.
In response, the front that moved through the northern portions
of the area should lift back towards the Red River as a warm
front. Isentropic ascent will commence atop the frontal surface
and with the cap still in a weakened state from the afternoon
hours, this could yield some isolated to possibly scattered
convective activity. The best rain/storm chances Saturday evening
into Sunday morning will be near and north of I-20. If deep moist
convection can establish itself, it`s possible that strong to
severe storms could occur given the plentiful deep layer wind
shear (50-60 knots) and MUCAPE values of around 1500 J/kg.

Sunday may offer slightly better prospects for rain/storms as the
dryline should be closer to our Big Country and Red River
counties. I`m still a little hesitant to go "hog wild" with
widespread PoPs as there isn`t a big sign of strong synoptic lift.
With the southwest flow aloft, however, there`s likely to be a
few shortwave troughs that ripple through the swift flow. Deep
layer wind shear and plentiful instability will support another
round of strong to severe thunderstorms. The main hazards at this
time appear to large hail and damaging winds, should storms
develop. There may be a brief reprieve from the rain chances
overnight Sunday into early Monday as the dryline retreats under
generally quiescent conditions and the boundary layer stabilizes

A stronger warm air advection regime should establish itself
during the day on Monday as the broad west coast trough continues
to slowly progress eastward. Increasing mid and upper level flow
should allow for an increase in moisture through the troposphere.
Forecast instability values aren`t as impressive on Monday
compared to the weekend and this could be due to increase cloud
cover and slightly flatter lapse rates. Deep layer shear, however
will increase and we may have to contend with another conditional
severe weather threat on Monday. As far as rain chances, there
continues to be decent consensus among both deterministic and
ensemble guidance. What we will need to monitor is the timing of
the upper level trough. If this features slows down, it could
delay the arrival of the strongest flow and thus best rain
chances. With a very moist regime (characterized by PWAT values in
the 1.25"-1.50" range) expected during the start of next week, we
may start seeing some periods of moderate to heavy rain. This
could result in some possible flood issues, especially if the axis
of heaviest rain is able to shift into portions of East TX. Right
now, it looks like the better threat for widespread rain will be
across parts of western North TX and into the Big Country.

The middle of next week looks to be unsettled though some model
discrepancies exist closer to Wednesday. The 12 UTC deterministic
ECMWF and a majority of its ensembles appear to be a bit more
progressive than that of the GFS. For now, I`ll keep PoPs fairly
broad-brushed to account for this uncertainty.



Dallas-Ft. Worth    52  79  59  80  65 /   0   0   0   5   5
Waco                48  79  59  82  64 /   0   0   5   5   5
Paris               45  73  55  75  62 /   0   0   0   5  10
Denton              49  77  59  80  63 /   0   0   0   5   5
McKinney            48  75  58  77  64 /   0   0   0   5   5
Dallas              52  78  59  80  66 /   0   0   0   5   5
Terrell             49  77  57  78  64 /   0   0   0   5  10
Corsicana           51  76  58  79  64 /   0   0   0   5  10
Temple              49  79  58  81  64 /   0   0   5   5  10
Mineral Wells       49  79  60  84  63 /   0   0   5   0   5




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