National Weather Service Raw Text Product

Displaying AFOS PIL: AFDFWD Received: 2018-08-10 20:05 UTC

FXUS64 KFWD 102005

Area Forecast Discussion
National Weather Service Fort Worth TX
305 PM CDT Fri Aug 10 2018

/Rest of Today and Tonight/

The large area of showers and thunderstorms which brought some
locally heavy rainfall to the region--some locales across parts of
Ellis and Navarro counties picked up in excess of half a foot
today--has greatly diminished in coverage over the last few hours.
Anticipate that this general trend will continue over the next
several hours as cloud cover continues to thin out. The high
temperature as of this writing at DFW airport is a frigid 75
degrees thanks to the pervasive rain and cloud cover. The record
low maximum temperature for the date is 80 degrees set all the way
back in 1915. Given the quickly thinning cloud cover, it seems
likely that temperatures will probably jump several degrees pretty
quickly (Denton went from 79 to 83 in a matter of minutes), so it
may be difficult to hold our high temperature under 80. 

The atmosphere across most of the region has been solidly
overturned by this earlier batch of showers and storms. With a
distinct lack of large-scale forcing for ascent, it seeps unlikely
that much additional storm activity will occur this afternoon
except potentially across our immediate Red River counties and
parts of Central Texas where the sun has returned and shallow
cumulus is bubbling. DCAPE across our far northern row of
counties is sitting around 800-1000 J/kg, so any additional
isolated activity here will pose a strong and gusty wind threat
into the early-evening hours. Think the fog threat appears pretty
low tonight given the anticipated resurgence in cloud cover, but
we'll keep an eye on observation trends this evening. 

Another modestly robust low-level jet is forecast to get cranking
once again later this evening and overnight. The resulting moist
isentropic upglide and warm advection will have little difficulty
squeezing additional rainfall out of the very moist atmospheric
column characterized by PWATs pushing past 2 inches. Forecasting
where the main area of associated ascent sets up isn't certain,
but it appears the best multi-model signal is along and west of
I-45 and along and south of I-20 overnight. As a result, we've 
raised PoPs in this area into the likely category after midnight. 
With the anomalous PWATs, deep warm cloud layers, and tall skinny 
CAPE profiles, we're once again concerned about a localized heavy 
to very heavy rain event across parts of the area overnight. The 
HREF probability matched mean products, which maintain ensemble 
QPF amplitudes by migrating the highest QPF values to the greatest 
probability locations, paint a bullseye south of I-20 and west of
I-35 overnight and into Saturday morning, which conceptually
matches up with the greatest lift from the LLJ. Given /1/ the
anticipated localized nature of the highest QPF totals, /2/
slight displacement from today's axis of heaviest rainfall, and 
/3/ decently high 1- and 3- hour flash flood guidance, we'll hold 
off on a small flash flood watch for this area. That said, there 
is certainly a localized flash flooding threat overnight, 
especially if heavier activity develops into portions of the I-45
corridor where very heavy rain fell today. 



/Saturday through next Friday/

Summary: Unsettled weather is expected to continue through early
next week, with warmer and drier weather expected by the end of 
the work week.

Similar to Friday morning, showers and thunderstorms will likely 
be ongoing Saturday morning along and south of the I-20 corridor
aided by a strong low-level jet. Heavy rain is possible across
Central Texas, and localized flooding issues are possible across 
areas that received ample rain today. The activity should move 
in a general northeast direction as the mean wind looks to be 
southwesterly, although some southward development into the low-
level jet will possible across Central Texas. High-res guidance 
is hinting at another round of activity Saturday afternoon, and 
have continued with broad brushed PoPs to account for the 
uncertainty in the location of this development.

In the synoptic scale, a shortwave will slide southwestward and 
become an upper level low on Saturday. Guidance seems to be in 
agreement that the upper level low will remain nearly stationary 
over the Texas Panhandle through the weekend, providing upper 
level support for storms. Model soundings show lapse rates of 
around 5.5-6.5 C/km... and weak shear values, generally below 
10-12 knots across the region, indicative of slow moving activity.
Given precipitable water values of 1.7"-2.0" across North and 
Central Texas, the overall environment is supportive of showers 
and thunderstorms. 

On Sunday, the highest rain chances will be across our 
southwestern to northeastern zones as there is indication of a
broad area of high pressure over the Gulf coast. This area is
expected to reach our southeastern zones with drier air on 
Monday, all while the stationary low slowly begins its move back 
into the main synoptic flow. The latest guidance shows some 
disagreement on the location of the low. The GFS continues to show
the low translated further north with the main flow, while a 
shortwave will push south into Oklahoma. The ECMWF is now showing
a slower movement of the upper level trough once the low is 
embedded back into the main flow. Because of the uncertainty, have
continued to maintain low PoPs along and north of I-20 through 

Temperatures will remain below normal through early next week, but
will gradually warm back to near normal temperatures by next 



.AVIATION... /Issued 1250 PM CDT Fri Aug 10 2018/
/18z TAFs/

An area of light to moderate rainfall, with some embedded heavier
convective elements and lightning, persists early this afternoon
across the I-20 corridor. The initiating ascent continues to
dwindle as low-level winds have veered and weakened, and
anticipate a gradual downtrend in coverage of rain and storms over
the next few hours across the D10 TRACON. Additional isolated to
scattered thunderstorms may develop through the afternoon near the
Red River in the vicinity of an associated outflow boundary, and
this activity may cause new disruptions to northbound departures
and arrivals through the Bowie and Bonham cornerposts. The
potential for thunder at the Metroplex TAF sites appears to be low
this afternoon within a heavily worked-over atmosphere. Similarly,
things looks pretty stabilized at Waco, and will refrain from
advertising additional convective chances through the daylight

Overnight, a similar scenario to this morning may once again play
out as another 30-35 kt low-level jet gets cranking and begins to
overtop the leftover outflow boundary from today's activity across
Central Texas. The associated ascent should squeeze out additional
showers and storms in the very moist airmass. The exact location
of better rain chances remains a bit uncertain, but showers and
storms seem like a good bet at Waco late this evening, with a
potential complex slowly spreading northward towards the Metroplex
late tonight and into Saturday morning. Rather than carry
prolonged VCTS at the TAF sites, will transition things over to
VCSH Saturday morning as convection scavenges available
instability. That said, the threat for thunder may linger
well into the afternoon hours as an additional wave of ascent



Dallas-Ft. Worth    74  87  75  86  76 /  60  50  60  60  70 
Waco                74  89  75  89  75 /  70  70  60  50  60 
Paris               72  87  72  85  74 /  20  50  40  60  50 
Denton              74  87  74  86  74 /  40  50  50  60  70 
McKinney            73  87  73  86  74 /  40  50  50  60  70 
Dallas              74  88  75  87  76 /  60  50  60  60  70 
Terrell             74  87  72  87  75 /  50  60  50  60  60 
Corsicana           74  89  74  89  75 /  50  70  60  50  40 
Temple              74  88  75  90  76 /  60  70  60  50  50 
Mineral Wells       73  87  73  84  71 /  60  50  60  60  70