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Area forecast discussion
National Weather Service Fort Worth Texas
328 PM CDT Wed Apr 26 2017

Discussion...
the strong cold front continues to make southeastward progress and
has nearly cleared the forecast area as of 3pm with the exception
of our far southeastern zones. A few showers and storms remain
immediately along the front but these also will be exiting the
area shortly. Strong pressure rises behind the front have resulted
in gusty northwest winds which are causing much cooler air to be
advected into the region. A Wind Advisory will remain in effect
area-wide through 7pm before wind speeds begin decreasing. Where
Post-frontal stratus has lingered, temperatures have held in the
50s throughout most of the day. A gradual clearing trend will
follow this evening and tonight. These clearing skies and light
winds will result in favorable radiational cooling conditions,
and temperatures are expected to fall into the 40s for most
locations by Thursday morning. Given todays rainfall and
lingering moisture, some patchy fog or at least some ground fog
will be possible, mainly along and east of I-35 and have included
a mention in the forecast. No dense fog is expected and any fog
that does develop should be short-lived. A warmer Thursday will
follow with winds quickly returning to the south.

Now that today's cold front and thunderstorms are out of the way,
the focus shifts to the Friday-Saturday time frame when our next
round of strong to severe storms is expected. There will be a
couple identifiable rounds with this system, the first being a
highly conditional severe storm threat late Friday afternoon and
evening which will depend on the available lift. The second round
will be on Saturday when strong to severe storms are likely in
the forecast area along another cold front.

Moisture will increase on Thursday as a warm advection regime
sets up across the Southern Plains. Temperatures will rebound
quickly, climbing back into the 70s and 80s area-wide with some
90s possible in our western zones. Moisture will be on the
increase during the day Thursday, setting the stage for
thunderstorm chances to end the week. By Friday afternoon, a
powerful upper trough will be digging southward into New Mexico.
In addition, plentiful Gulf moisture will be in place in the warm
sector of a deepening surface low located in the Texas Panhandle.
This warm sector will be bound by a quasi-stationary front near
the Red River and a sharp dryline positioned from SW Oklahoma
southward into Texas. While the capping inversion is forecast to
be fairly weak during this time across north TX, the main question
will be if strong enough lift will be able to generate storms
during this time, either along the dryline with aid from the
approaching trough, or near the quasi-stationary front which
should begin lifting northward through Oklahoma as a warm front.
If storms are able to develop within this quality warm sector
airmass, they will have the potential to quickly become severe
with cape values exceeding 4000 j/kg and deep layer shear of 40-50
kts. Supercells would be supported by these conditions with all
modes of severe weather possible. However, this potential remains
highly conditional on the strength of the cap and available lift,
and confidence remains low in the convective potential during this
time.

There is higher confidence regarding thunderstorm chances
beginning late Friday night and Saturday as a strong cold front
arrives from the north. The approaching upper trough will aid in
the development of widespread thunderstorms in the vicinity of
the southeastward-moving cold front. Severe thunderstorms are
possible across nearly our entire forecast area throughout
Saturday, although the entire day probably won't be a washout.
All modes of severe weather will be possible on Saturday as well,
although large hail appears to be the primary severe weather
hazard. How quickly convection grows upscale will determine the
extent of the tornado or wind threats, but forecast hodographs are
not the most favorable for tornado potential at this time. Flash
flooding will also be of concern, especially across our
northeastern zones where the highest rainfall amounts are
currently forecast. Some spots could see 2-4 inches of rain by
the time convection ends late Saturday night with some locally
higher totals possible. Rain amounts should be quite a bit less to
the west and southwest. Unless the system digs farther south and
slows down from the current forecast, am not expecting a terribly
widespread flood threat at this point. Given latest guidance,
rain is expected to be coming to an end from west to east by
Sunday morning at the latest as the cold front clears the area.

A couple of quieter days will follow on Monday and Tuesday with
highs bouncing back to near or above seasonal normals. Guidance
is in fairly good agreement regarding our next shot at storms
during the midweek time frame. Another deep trough is expected to
deepen to our west which should drive another cold front through
the area sometime on Wednesday.

-Stalley

&&

Aviation...



/issued 1140 PM CDT Tue Apr 25 2017/
breezy south winds will persist overnight with occasional gusts
to around 25 kts or so, and MVFR cigs will prevail at all sites. A
nocturnal bore feature can be seen entering the region on radar
imagery, and recent surface observations from krph indicate that a
northwest wind shift accompanies this feature. Should this
move across the metroplex sites, any wind shift would be brief,
with a quick return to breezy southerly winds.

The main change from the 00z tafs was to introduce a mention of
thunderstorms in the vicinity at all metroplex sites as it seems likely sufficient lifting
will occur to erode the lingering capping inversion as the main
cold front arrives. Waco looks to remain far enough removed from
the better forcing to preclude an explicit mention of thunder, but
have inserted a brief window of vcsh to account for southwestward
precip development. An abrupt northwest wind shift will accompany
the front, which should arrive between 13-14z at western sites,
and 14-15z across the eastern metroplex sites and Waco.
Convective chances will quickly come to an end by 15-16z as cooler
and drier air filters in. Cloud bases will then begin to rise,
eventually to VFR Wednesday afternoon.

Winds will then slacken as high pressure builds in overhead, and
airports will likely be able to return to south flow late
Wednesday evening. As winds go nearly calm, there is some
potential for a shallow layer of fog to materialize, but this
potential is too low to include in the tafs at this time.

Carlaw



&&

Preliminary point temps/pops...
Dallas-ft. Worth 49 81 67 88 71 / 0 0 0 20 50
Waco 47 82 68 89 73 / 0 0 0 10 20
Paris 42 76 59 83 67 / 10 0 5 30 60
Denton 43 80 65 86 68 / 0 0 5 20 50
McKinney 44 78 63 85 69 / 0 0 0 20 50
Dallas 50 82 68 88 71 / 0 0 0 20 40
Terrell 47 80 64 86 70 / 0 0 0 20 40
Corsicana 47 81 66 88 72 / 0 0 0 10 20
Temple 48 83 69 89 73 / 0 0 0 10 10
Mineral Wells 43 85 64 89 66 / 0 0 0 20 40

&&

Forward watches/warnings/advisories...
Wind Advisory until 7 PM CDT this evening for txz091>095-100>107-
115>123-129>135-141>148-156>162-174-175.

&&

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