Forecast Discussion for Dallas/Ft. Worth, Texas

000
FXUS64 KFWD 301047
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
547 AM CDT Mon Mar 30 2020


.SHORT TERM... /NEW/
Update:

Minimal changes were made to the previous forecast other than to
account for ongoing trends so far this morning. The potential for
strong or severe storms today still appears rather low at this
time. The main focus through the rest of the day will be tracking
the northward progress of the warm front which will determine
whether any noteworthy surface-based instability can creep into
our Central Texas zones during the afternoon. This would be the
main area of concern for severe weather, with only a risk for
elevated storms across the remainder of the CWA. A low-end flood
risk is still expected across parts of East Texas where rain
totals will likely range from 1-2 inches.

-Stalley

Previous Discussion:
/Through Monday Night/

The main focus through the short-term is the low-end potential for
a few strong/severe storms later today, along with an isolated
flood threat.

Isentropic ascent continues to increase ahead of a sharpening
upper trough approaching from the west. This shortwave will
intensify and transition to a neutral tilt as it enters the
Plains later today, but in the meantime, broad ascent and top-down
saturation will result in widely scattered showers and isolated
storms through the rest of the morning. No severe weather is
expected through midday.

This afternoon, a warm front accompanied by rich Gulf moisture
will nose into parts of Central Texas, while a surface low
associated with the aformentioned shortwave develops to our
northwest. A dryline boundary will sharpen along the moisture
gradient to our west, oriented north-south from the new surface
low. A narrow buoyant sector will materialize immediately along
the dryline, most of which will consist of elevated instability
given the rather cool boundary layer. Nearly all surface-based
instability will be confined south of the warm frontal boundary,
and the vast majority of the CWA will remain positioned on the
north side of the warm front throughout the day. As stronger
ascent impinges on the area this afternoon, widespread elevated
convection will develop, with access to shallow pockets of steep
lapse rates in the mid levels. This will mean a threat for hail
with any robust updrafts, especially given the strong effective
bulk shear in place. By late afternoon or evening, the focus will
shift to our southern and eastern zones where some surface-based
instability should reside near the intersection of the warm front
and eastward-moving dryline. This area should have the greatest
risk for a strong or severe storm, but the overall threat will be
limited due to lackluster instability within the lowest 3 km.
Also during this time period, some training of convection is
possible across eastern portions of the forecast area where
rainfall totals exceeding 1 inch seem likely. This may result in
isolated occurrences of minor flooding and perhaps an instance or
two of flash flooding. All convection is expected to shift east of
the CWA by mid to late evening.

As the surface low continues its eastward trek, its attendant
cold front will move into North Texas during the evening and
overnight hours. In vicinity of this boundary, areas of fog and
drizzle are possible as weak overrunning occurs, while moist
advection into an already-saturated boundary layer continues.
Gradual clearing should occur as dry air begins advecting into
the area prior to daybreak Tuesday, but low clouds and patchy
drizzle could persist mainly east of I-35 during the early morning
hours.

-Stalley

&&

.LONG TERM... /Issued 252 AM CDT Mon Mar 30 2020/
/Tuesday and Beyond/

A nice start to the forecast period is in store as the Monday
system shoves off to the east and shortwave ridging develops
overhead. Conditions will be a tad breezy on Tuesday due to good
pressure rises behind the cold front. North winds of 15 to 20 MPH
look likely for most of the day with highs ranging from the mid
60s along the Red River to lower and mid 70s across Central Texas.
Winds will drop off in the evening as the surface ridge moves
in, then become light southeasterly by daybreak Wednesday as the
ridge axis slides east into Louisiana. Light winds and mostly
clear skies will allow overnight temperatures to drop into the
upper 40s and lower 50s. Similar temperatures to Tuesday can be
expected on Wednesday, but winds will increase out of the
southeast as lee-side troughing strengthens ahead of a pair of
upstream shortwaves.

The first of these appears fairly weak and will pass rather
quickly overhead within the southern stream of a split flow
regime on Thursday. Questionable moisture return ahead of the
system will keep POPs in the slight chance to chance categories.
That said, it does appear that a dryline may serve as a focus for
afternoon thunderstorm development as it nudges into the western
zones, so POPs have been bumped up above blended guidance for
areas along and west of Highway 281. Any storm which pops up near
the dryline will have access to favorable amounts of instability,
and would be capable of producing hail and gusty winds. Scattered
showers and isolated sub-severe thunderstorms will be the story
across the rest of the region through the evening hours, with
precip ending overnight as the disturbance exits to the east.

The second system is a larger-scale trough embedded in the
northern stream which will propagate eastward across the Central
Plains on Friday, pushing a cold front south through the region.
The front will already be on our doorstep by daybreak Friday,
exiting to the southeast by sunset. Isolated thunderstorms will
accompany the front in the morning before increasing (both in
coverage and intensity) in the afternoon due to a sharp increase
in diurnal instability. Another potential for strong to isolated
severe convection will exist, this time mainly east of I-35 and
south of I-20 in the afternoon. Storms will likely evolve into a
loosely organized squall line while exiting to the south and east
of the region Friday night.

A break in the weather looks like a good possibility for Saturday
and Saturday night as the northern trough heads for Ontario and
ridging develops aloft. This will be short-lived, however, as
isentropic ascent increases once again ahead of a deepening upper
low along the West Coast. Clouds will increase during the day
Sunday with rain showers becoming possible by Sunday afternoon.
There is much discrepancy in mid-range guidance regarding the
progression of the upper level system, so it is uncertain how long
the rain chances will continue into next week. Will keep at least
slight chance POPs going into next Monday and plan on adjusting
the numbers as models come into better agreement.

30

&&

.AVIATION... /NEW/
/12z TAFs/

One round of ascent allowed showers and isolated storms to move
through a few of the TAF sites overnight, but this activity has
since shifted northward with a lull in precip expected at the
terminals over the next few hours. However, more widespread
showers and storms will begin to develop later this morning and
into this afternoon, with several hours of TS impacts expected at
most airports. Winds will remain ESE throughout this time, while
cigs progressively lower to MVFR by late morning and IFR during
the afternoon. Most convective activity is expected to shift east
of the TAF sites by 00-01z. Thereafter, IFR/LIFR conditions will
exist with areas of mist/drizzle/fog occurring prior to a cold
frontal passage overnight. As this front moves through during the
pre-dawn hours Tuesday, cigs will lift and begin scattering as dry
air advects into the region, with VFR resuming later Tuesday
morning.

-Stalley

&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    63  54  70  51  71 / 100  40   0   0   0
Waco                65  56  72  50  72 /  90  20   0   0   0
Paris               60  51  66  46  67 / 100 100   0   0   0
Denton              61  53  69  49  70 / 100  40   0   0   0
McKinney            60  52  68  49  69 / 100  70   0   0   0
Dallas              63  53  70  51  70 / 100  50   0   0   0
Terrell             63  53  70  49  70 / 100  90   0   0   0
Corsicana           65  57  70  50  69 / 100  70   0   0   0
Temple              67  54  74  50  72 /  80  10   0   0   0
Mineral Wells       64  53  70  48  71 / 100  10   0   0   0

&&

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

$$

26/30

NWS FWD Office Area Forecast Discussion