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

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FXUS64 KFWD 222031
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
331 PM CDT Mon May 22 2017

.SYNOPSIS...
Intermittent rain from this morning continues to dwindle as the
corridor of best ascent shifts eastward. There will be a couple of
opportunities for showers and storms over the next 24-48 hours
with a few strong to severe storms possible. Thereafter, there
will be a cold front that should end rain chances for a majority
of North and Central TX. The middle to end of the work week
appears precipitation-free with hot conditions. Low rain chances
return just in time for the Memorial Day Weekend.

&&

.SHORT TERM (Tonight through Tuesday)...
Light rain and drizzle continues to diminish across Central and
East TX as isentropic ascent along the 305K theta surface shuts
off and actually transitions to more in the way of downglide. The
decaying complex across Oklahoma associated with the initial upper
trough embedded in the zonal flow has all but evaporated leaving
just a few lingering mid-level clouds. Farther upstream, new
convection across the Caballo Mountains across New Mexico and
northwest Oklahoma has already started to develop. This activity
is along a second shortwave trough forecast to slide southeastward
towards North and Central TX over the next 12-18 hours.

For the remainder of the afternoon---Generally quiet weather
conditions are expected with perhaps some lingering light rain
showers out across eastern zones. A thunderstorm or two may
develop across far northwestern zones this afternoon, but overall
prospects look low through about 00 UTC given no discernible
forcing for ascent. If a storm does develop and become strong, the
main threats would be gusty outflow winds and perhaps some near-
severe hail. Otherwise, a majority of North and Central TX should
remain dry with partly to mostly cloudy skies.

For tonight---the chances for rain increase from west to east as
a convective complex gradually grows upscale per hi-resolution
mesoscale models. This seems somewhat plausible as an amplifying
shortwave trough is advertised by the coarser resolution guidance
to slide east and southeastward through the Big Country. Forecast
soundings suggests that lapse rates will quickly steepen with
magnitudes of up to 8 C/km in the hail growth region. While the
storm mode will generally be in the form of a cluster or small
line segments, strong winds appear to be a secondary concern given
the elevated nature of the convection as the low levels appear to
be quite stable. We will have to monitor the heavy rainfall
potential as already swollen small basins may become aggravated by
any additional rainfall. Fortunately, the overall progression of
the complex of storms should be swift enough to largely mitigate
this threat.

As mentioned in the morning update, I`ve confined the highest
rain chances to areas northwest of a Lampasas to DFW to Bonham
line through 03 UTC. Thereafter, I have expanded PoPs for rain
across all of North and Central TX, with the most likely areas for
storms being near and west of a Gainesville to Corsicana to
Hearne line. Farther east of this line, there`s a great deal of
uncertainty as to whether or not the complex maintains itself.
Given the weak low level wind field, I`ll taper PoPs quite
dramatically out across the eastern fringes of North and Central
TX. In fact, there remains a chance that some parts of East TX may
see little to no precipitation.

For Tuesday---Rain chances will continue on Tuesday morning with
perhaps a lull during the late morning to early afternoon hours.
Thereafter, a cold front should slide southward ahead of a very
amplified upper trough. Given the breadth of this upper trough,
it`s likely that strong cold advection will drive this front
through all of North and Central TX. The airmass east of the front
is characterized by 1000-1500 J/kg of CAPE with deep layer shear
around 20 to 35 knots which could support some organized storm
structures. At this time, the main hazards would likely be hail
and wind. Heavy rain may also result in some minor flooding,
especially if areas experience both a morning and evening round of
storms. Rain chances will quickly end from northwest to southeast
as a front clears the area. Breezy north winds in the wake of the
front are expected. Low level wind profiles from the GFS aren`t
too overly impressive, so sustained winds of 15 to 20 MPH with
perhaps some gusts to near 30 MPH seem most likely. Cooler
conditions will be ushered in with slightly drier conditions as
the front barrels southward towards the TX Gulf Coast.

The drier air in place on Tuesday night into Wednesday morning
should make for some unseasonably cooler conditions. In fact, some
areas may flirt with record low temperatures as the thermometer
will dip down into the upper 40s for some locales. The one
potential fly-in-the-ointment will be that 925mb winds may still
remain elevated. For now, we will monitor and make adjustments as
necessary.

&&

.LONG TERM (Wednesday through Saturday)...
For Wednesday---Generally dry conditions are expected in the wake
of Tuesday`s cold front. Most areas should see a fair amount of
sun, but some cold advection aloft will help to steep mid and low
level lapse rates. In response to the steepening lapse rates,
stratocumulus is expected to build from the northeast zones down
towards the DFW Metroplex. This will likely temper some heating,
especially across cloud covered regions. I won`t tank temperatures
too far as northwest winds should help to promote some downslope
warming. Temperatures beneath the straocu deck may only climb into
the 70s, while more cloud-free areas experience temperatures in
the low to mid 80s. With the H5 ridge building aloft, little to no
precipitation is expected, with perhaps some sprinkles out across
far northeastern zones.

Wednesday night should see temperatures moderate as low level
flow responds to troughing to the north. Overnight low
temperatures will only fall into the upper 50s with 60s across
southern and western zones where low level moisture will begin to
lift northward. An increase in the surface wind field will also
help to keep the boundary layer well mixed.

For Thursday and Friday---Thursday and Friday will perhaps be the
hottest of the year thus far. Hard to imagine after some areas
may flirt with near record low temperatures on Wednesday morning.
While low level moisture will continue to lift northward, surface
to 850mb winds veer towards the south-southwest and west,
respectively. This should promote very favorable conditions for
strong adiabatic compression with 850mb temps pushing 25-27 C in
some cases. The subsequent mixing should allow temperatures to
soar into the mid to even upper 90s out across western zones with
perhaps even some triple digit heat possible! Elsewhere,
temperatures should climb into the low to mid 90s. The threat for
rain will remain very low during this time as high pressure aloft
should suppress any attempts at convection.

For the Memorial Day Weekend---The hot weather appears to come to
an end just in time for the Memorial Day Weekend. Unfortunately,
at this time, that may come at the cost of some potential showers
and thunderstorms. Fortunately, at this time, however, it appears
that capping should largely mitigate a complete washout for those
with outdoor festivities. Should storms develop, however, they
will have the potential to pack a punch as good amounts of
instability and wind shear will likely be present. Given the
expected capping as well as the location of the upper forcing
(though the dryline may be in play), I`ll only advertise 20-30%
coverage of storms as there remains too much uncertainty with
regards to the speed and position of the upper trough to the
west. We will continue to make refinements to this portion of the
forecast given the high likelihood of the plethora of Holiday
Weekend outdoor events.


24-Bain

&&

.AVIATION...
/18Z TAFs/

A very challenging day as the old surface front remains well
south of the area. In addition, moist soils from overnight rains
are combining with late May heating and a shallow frontal
inversion to result in cigs at various levels. This is making the
cig forecast very challenging with potential for IFR at Waco and
MVFR at DFW sites possible through mid-late afternoon. Timing the
next northern branch trough and embedded shortwave disturbances
also presents a challenging 9-30 hour cig forecast.

Currently, we continue to watch the previous southern stream
shortwave that resulted in widespread rains from I-20 and points
south exit the area. A respite in convective activity will
continue through mid-late evening, as we remain more under an area
of subsidence from the first departing southern stream shortwave.
The next disturbance can be seen on satellite moving southeast
across the OK/TX Panhandles and northern OK. The first shortwave
will give us increasing convective chances across the airports
during the morning hours on Tuesday. Another reprieve is likely,
until a cold front and second shortwave arrive Tuesday afternoon
with yet another round of convection

For DFW airports...
We`ll continue to advertise spotty MVFR cigs this afternoon, then
see VFR through late evening, before MVFR cigs return. Will
introduce VCSH for the late evening hours with the approach of
the first shortwave, with VCTS in the 08Z-13Z period. Afterward,
there is a high degree of uncertainty, but will slowly bring DFW
airports back to VFR beyond the 24 hour period. For now, left
VCTS out of the 24-30 hour forecast and will let future issuances
address that time period with better confidence.

For Waco...
Similar trends to DFW area airports except IFR cigs early this
afternoon and perhaps a slight delay on convective timing
overnight and into Tuesday. In addition, they may not break out to
VFR at all Tuesday if the cold front gets in there relatively
early in the day as expected.

Look for light ENE-ESE winds less than 10 kts, going variable
ahead of the cold front later tonight. All sites will likely see
FROPA either side of 12Z Tuesday with winds NW 5-10 kts,
increasing to 10-15 kts Tuesday afternoon.

05/


&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    76  63  75  56  82 /  10  40  40  10   5
Waco                73  61  76  54  83 /  20  50  40  20   5
Paris               76  59  71  52  75 /  10  40  40  10   5
Denton              76  60  73  50  79 /  10  50  40   5   5
McKinney            75  59  74  53  79 /  10  40  40  10   5
Dallas              76  63  75  57  81 /  10  40  40  10   5
Terrell             73  61  76  54  79 /  10  40  40  10   5
Corsicana           72  63  76  55  82 /  30  50  40  20   5
Temple              73  62  76  54  83 /  20  50  40  20   5
Mineral Wells       75  59  73  50  82 /  20  50  40  10   5

&&

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

$$

05/24



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