Tornado and Hail in Texas, March 9, 2019

Area Forecast Discussion
National Weather Service Fort Worth TX
1137 PM CST Fri Mar 8 2019

.AVIATION...
/06Z TAFs/

Concerns and challenges: Timing of convection. Isolated storms
already going up around KABI/KBKD/KGZN. Most of this activity is
moving NNE 30-40 knots. Have kept general timing between 09z-14z
across DFW Metro airports, but delayed start of things at Waco
where a capping inversion may delay things to between 11z-14z.
Some strong-severe storms with large hail expected. Depending how
well the cap holds, it's possible some localized very gusty winds
in excess of 40 knots will be possible as this system moves
through.

Otherwise, a 35-45 knot LLJ over NC TX has allowed MVFR cigs to
spread northward across Waco and eastern Metro airports already,
and will spread across western Metro airports within the next
hour. Cigs may briefly rise to above FL020 with stronger
convection and toward 12z, with the gradual veering of low level
flow and increasing upward ascent.

Otherwise, timing the prefrontal trough/dryline in between 13z-15z
still looks reasonable with surface winds shifting W/WSW 15-20
knots with gusts 25 knots+ looking likely. VFR conditions return
with strong westerly winds 15-25 knots, diminishing to between
10-15 knots early-mid afternoon.

05/

&&

.SHORT TERM... /Issued 315 PM CST Fri Mar 8 2019/
/Tonight through Saturday/

Early afternoon moisture channel imagery depicts a
deepening/sharpening upper trough draped from the Great Basin,
southward into Baja California. This feature will continue to
translate eastward this evening and overnight, and will be
responsible for driving a round of potentially strong to severe
convection through our forecast area. In the meantime, surface
analysis places a quasistationary front from near Gainesville to
Decatur to Breckenridge, but this feature will continue to wash
out and push north of the Red River this evening. Temperatures
ahead of the front have soared well into the 70s, about 10 degrees
above climatological normals for this time of year--pretty
remarkable considering we were dealing with single-digit wind
chills on Monday morning.

The rest of the afternoon and mid-evening hours should remain
pretty tranquil as we await the arrival of stronger forcing for
ascent associated with the aformentioned upper trough. In
addition, our special 18z sounding in support of VORTEX-SE sampled
extremely warm and dry conditions at 850 mb with temperatures
pushing +21 C. This represents the base of a notable EML plume
characterized by mid-level lapse rates nearing 8 C/km. With scant
low-level moisture and a lack of large scale forcing, this feature
will quite effectively cap us off to any convection at least
through mid-evening. The current thinking is that shower and
thunderstorm chances will remain low across our forecast area
through about 11 PM to midnight.

More notable mid-level heights falls, heralding the approach of
stronger forcing for ascent, will overspread the region late this
evening and overnight. As this occurs, lifting/moistening of the
capping inversion will commence, eventually opening the door to
the development of deep moist convection around or shortly after
midnight. Latest CAM guidance is in fairly good agreement in an
initial round of what appears to be elevated convection developing
across the Concho Valley and tracking northeastward towards
locales roughly along and west of I-35 in association with
increasing low-level warm advection. A lingering pocket of fairly
dry air is present in point forecast soundings in the 700 to 850
mb layer, and this adds a layer of complexity/uncertainty to the
forecast as it's unclear how/if this may deleteriously impact
updraft vigor. If initial updrafts can overcome and moisten this
layer, they would have access to the very steep lapse rate plume
aloft and sufficient deep layer shear to support rotating
updrafts. This initially activity would pose a threat for large
hail to perhaps golfball-size or slightly larger.

The latest guidance is indicating a potential for rapid upscale
growth into a broken linear complex as this activity presses
towards the I-35 corridor late tonight (after about 2-3 AM) as
increasing ascent encourages additional thunderstorm development.
Low-level lapse rates don't look all that impressive, indicating a
propensity for any updrafts to ingest parcels rooted mainly above
the surface. However, effective inflow bases may lower towards
the surface if a mature squall line materializes, delivering a
strong to locally damaging wind threat into the Metroplex and
points east of I-35 late tonight. The tornado potential still
appears low given limited low-level instability and rather veered
low-level flow, but conditions may become marginally more
favorable for locales both north of I-20 and east of I-35/35E.

As this initial activity moves off to our east around daybreak on
Saturday, additional convection may fire along the incoming
Pacific front, perhaps right along the I-35 corridor around 5-7
AM. The steepest lapse rates will be shifting off to the east
during this timeframe, and the potential for parcels to ingest
recently convectively-processed air may temper the severe threat
with this second wave somewhat. That said, large scale forcing
will be intense, so would anticipate a continued severe threat
(quarter-sized hail and some localized damaging wind gusts).

Activity will finally clear our CWA completely just before noon
on Saturday leaving behind breezy west winds and rapidly clearing
skies. The strong downsloping component to the low-level flow
should allow temperatures to soar back into the 70s and even lower
80s even though we'll be located behind a cold front.

Carlaw

&&

.LONG TERM... /Issued 315 PM CST Fri Mar 8 2019/
/Saturday Night through Friday/

Dry and subsident air will continue to filter into the region
Saturday night as an upper trough moves quickly northeast and a
weak cold front moves in from the north. The cold front will
stall across the forecast areas Sunday morning as another upper
level low pressure system deepens off the West Coast. Although
large scale lift will steadily increase through the day and upper
level moisture will increase, the chances for any precipitation
will be low and likely confined to locations near the stalled
front. Since it will be difficult to pinpoint exactly where the
cold front will be Sunday, we will keep PoPs in the 20 to 30
percent range.

Large scale lift and warm air advection will both increase across
the region Sunday night through Monday as the upper low
intensifies and drops south near the Baja Peninsula. Deep moisture
and increasing mid level destabilization will result in numerous
showers and isolated thunderstorms with the best rain/storm
chances across the west.

The upper low is progged to begin to open up and lift across the
Desert Southwest Monday night/Tuesday with the best lift and
instability shifting eastward into North and Central Texas.
Therefore, thunderstorms will become more numerous through Tuesday
with a some potential for strong/severe storms. However, the
larger threat will likely be from locally heavy rainfall as
precipitable water values increase to around 1.5 inches and the
potential for training storms increases. We will continue to
assess the severe weather potential in the coming days, but with
abundant moisture and strong dynamics in place some severe
weather is a pretty good bet.

The upper low should finally translate east across the state
Tuesday night and Wednesday, resulting in another round of showers
and thunderstorms followed by a quick end to the precipitation
from west to east Wednesday afternoon with the arrival of a
Pacific cold front. It will become windy and much drier behind the
front, however, we do not anticipate any significant wild fire
concerns since all areas are expected to get appreciable rainfall
prior to FROPA.

The second half of next week should be dry and a bit cooler with
the passage of a stronger cold front late Thursday into Friday.

79

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    63  76  48  59  49 /  90  40   0  20  50
Waco                65  79  50  65  52 /  90  50   0  20  40
Paris               64  76  46  56  47 / 100  70   0  20  40
Denton              62  76  45  56  47 /  80  40   0  20  50
McKinney            63  75  46  57  47 /  90  50   0  20  40
Dallas              64  77  50  59  50 /  90  50   0  20  50
Terrell             64  76  47  59  50 / 100  60   0  20  50
Corsicana           65  77  50  62  51 / 100  70   0  20  40
Temple              64  81  51  67  54 /  70  50   0  30  40
Mineral Wells       59  77  45  58  47 /  70  20   0  30  50

&&

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

05/08

Hazardous Weather Outlook
National Weather Service Fort Worth TX
324 PM CST Fri Mar 8 2019

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-091145-
Montague-Cooke-Grayson-Fannin-Lamar-Young-Jack-Wise-Denton-Collin-
Hunt-Delta-Hopkins-Stephens-Palo Pinto-Parker-Tarrant-Dallas-
Rockwall-Kaufman-Van Zandt-Rains-Eastland-Erath-Hood-Somervell-
Johnson-Ellis-Henderson-Comanche-Mills-Hamilton-Bosque-Hill-Navarro-
Freestone-Anderson-Lampasas-Coryell-Bell-McLennan-Falls-Limestone-
Leon-Milam-Robertson-
324 PM CST Fri Mar 8 2019

This Hazardous Weather Outlook is for North and Central Texas.

.DAY ONE...Tonight.
Thunderstorm chances will increase around midnight tonight and
continue into Saturday morning. Some storms could become strong or
severe, particularly near and east of Interstate 35. Large hail will
be the main threat with stronger storms overnight, but localized
damaging wind gusts will also be possible.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.
Thunderstorms will continue through the mid-morning hours on Saturday
before moving east of the area by midday. Strong to severe storms may
continue through the morning hours east of Interstate 35 with
predominantly a hail and strong and gusty wind threat.

Thunderstorm chances will return on Monday and continue through the
first half of the week. Some strong or severe storms may be possible
throughout this time period, and flooding concerns may also arise
after multiple days of rainfall.

.SPOTTER INFORMATION STATEMENT...
Spotter activation may be requested after midnight tonight.

Carlaw

Special Weather Statement
National Weather Service Fort Worth TX
249 AM CST SAT MAR 9 2019

TXZ115-090930-
Stephens TX-
249 AM CST SAT MAR 9 2019

...SIGNIFICANT WEATHER ADVISORY FOR STEPHENS COUNTY UNTIL 330 AM
CST...

At 249 AM CST, Doppler radar was tracking a strong thunderstorm over
Ibex, or 11 miles southeast of Albany, moving northeast at 60 mph.

Nickel size hail will be possible with this storm.

Locations impacted include...
Breckenridge, Necessity, Crystal Falls and Us-
180 Near The Shackelford-Stephens County Line.

LAT...LON 3280 9910 3296 9889 3295 9858 3264 9858
      3254 9910
TIME...MOT...LOC 0849Z 240DEG 60KT 3265 9912

30

Special Weather Statement
National Weather Service Fort Worth TX
305 AM CST SAT MAR 9 2019

TXZ129-090945-
Eastland TX-
305 AM CST SAT MAR 9 2019

...SIGNIFICANT WEATHER ADVISORY FOR EASTLAND COUNTY UNTIL 345 AM
CST...

At 304 AM CST, Doppler radar was tracking a strong thunderstorm near
Atwell, or 11 miles southwest of Cisco, moving east at 65 mph.

Nickel size hail will be possible with this storm.

Locations impacted include...
Eastland, Cisco, Ranger, Gorman, Rising Star and Carbon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so closely monitor for additional
information or possible warnings from the National Weather Service.

&&

LAT...LON 3251 9911 3251 9847 3230 9848 3208 9893
      3208 9912
TIME...MOT...LOC 0904Z 249DEG 58KT 3231 9915

30