Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/11/17
Area Forecast Discussion
National Weather Service Brownsville TX
632 PM CDT Wed May 10 2017
.DISCUSSION...Updated for latest aviation discussion below.
.AVIATION...Breezy conditions expected to continue through this
evening before diminishing slightly overnight. MVFR cloud deck
will move in late this evening and continue through the overnight
hours with ceilings lowering around midnight. Some model guidance
indicates IFR ceilings developing by early morning, but confidence
is low in that scenario and have opted to maintain MVFR
conditions. Ceilings expected to improve by midmorning. Southeast
winds remain breezy Thursday and increase by midmorning with
gusts in the 25 to 27 knot range possible once again.
.PREV DISCUSSION... /issued 236 PM CDT Wed May 10 2017/
SHORT TERM (Tonight through Thursday Night): Look for convection
to develop to the west tonight over Mexico, with the CWA in a
general thunderstorm outlook area. The HRRR kicks things off late
this afternoon to early this evening, with convection heading
toward Webb County. A few cells could develop farther south, and
therefore be able to move across the Upper Valley through the
night, according to the HRRR, but the GFS is less emphatic,
showing a slightly weaker signal around 03Z. The NAM also picks up
on the signal and keeps it going past midnight. Kept 20 percent
pops in overnight for the Upper Valley. Any storms that developed
would track generally northeast, with lightning and and strong
winds the main threat.
Thursday will be another day with a mix of clouds and sun. Cloudy
skies tonight will slowly mix out on Thursday as southeast winds
crank to breezy again, with Gulf high pressure still strong enough
to drive the wind. Lower pressure will be located more to the north
than northwest, but the gradient will still support breezy winds as
a front edges closer. 850 mb winds do tend to veer slightly toward
southwest, so added a couple of degrees to high temps for the day,
to account for the downsloping. A few coastal and streamer showers
will be possible Thursday night into Friday morning, and guidance is
picking up on light fog Friday morning as winds decrease to light
while dew points remain enhanced.
LONG TERM (Friday through Wednesday):
The weak late-season cold front will be dragging into the region
during the day Friday, being pushed by the H% trough moving across
the ArkLaTex. While it does look more likely that the front will
stall in our area, the airmass difference on either side of the
boundary will be minimal, meaning the only noted difference will
be winds shifting more to the northeast Friday into Saturday.
Models still show a strong cap from drier air aloft, so forcing on
the front will not be enough to spark shower activity on Friday.
Surface high pressure drops into northeast Texas on Saturday,
continuing the light northeast winds through the day. The surface
high moves into the northern Gulf Sunday, swapping winds back to
the southeast. The area remains under a broad H5 ridge through the
first half of the upcoming week, so nil rain chances and
continued upward trend of temperatures through the 90s each
Now through Thursday night: Interaction between Gulf high pressure
and lower pressure inland will maintain stronger winds and
elevated seas through Thursday, with improvement late Thursday
into Friday. Small craft advisory conditions prevail on the Laguna
Madre today, while conditions on the Gulf appear borderline.
Southeast winds and the associated seas are within the margin of
error for an advisory, if not clearly above. At any rate, a SCA is
posted through 7 pm this evening for all marine areas. Should be
able to expire the Laguna advisory at 7 pm, and although
conditions should improve on the Gulf tonight, will let oncoming
crew make the final decision on timing.
Friday through Sunday: Conditions over the weekend will be much
improved as a weak front stalls in the vicinity of the lower Texas
coastal waters. The gradient will remain weak, producing light
northeast winds Friday into Saturday, generally less than 10
knots. Seas will respond, falling to 3 feet on Friday and 2 feet
or less later Saturday into Sunday. Winds Sunday will gradually
turn back to the southeast as the surface high moves into the
northeast Gulf, but will remain around 10 knots through Sunday
GM...Small Craft Advisory for winds until 7 PM CDT this evening for
Small Craft Advisory until 7 PM CDT this evening for GMZ150-155-
This product is also available on the web at:
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1200 AM EDT Thu May 11 2017
Area of rainfall anchored north of low pressure tracking across
Indiana will expand across the southeast Michigan airspace early
this morning. Limited potential does exist for some embedded
elevated thunder as well across the Detroit corridor. Accompanying
reduction of ceiling height will largely remain at VFR levels, but
there will be a window for brief/marginal MVFR conditions during the
morning period from PTK southward. Thicker canopy of cloud cover
carrying cigs at the 4-7 kft level lasting well into Thursday before
greater drying commences. Modest northeast wind through the period.
For DTW...There exists a very low probability for the inbound area
of rainfall to contain a brief period of elevated thunder early this
morning. Will continue to monitor trends before inclusion.
Otherwise, increasing potential for cigs to fall below 5000 ft as
this moisture rolls through this morning.
//DTW THRESHOLD PROBABILITIES...
* Medium for ceiling 5000 ft or less late tonight and Thursday.
* Low for thunderstorm occurrence early this morning.
Issued at 347 PM EDT Wed May 10 2017
Shortwave ridging aloft is currently working across the central
Great Lakes region this afternoon. The ridge is amplifying, inducing
greater production of high clouds over the region. Farther upstream
deep convection has initiated over northern Illinois and southern
Iowa - providing more high-level moisture for the balance of the
daytime hours. Otherwise, light southeasterly flow will aid in
maintaining a dry near surface layer.
The ridge amplification is contributing to an increase in the anti-
cyclonically curved upper-tropospheric jet. Moreover, a jetlet over
Kansas is projected to merge into the entrance region of the upper
jet. These two mechanism will spur on better forcing within the
right entrance region / flank of the jet - augmented by the
curvature. The early stages of this forcing is contributing to the
current convective response. This activity is also rooted in a
ribbon of frontogenesis on the 300K surface in the 850-800mb layer.
As the changing kinematics continue to increase the dynamic
response, the lower-tropospheric frontal zone will gain much greater
definition across southern Lower Michigan overnight. As this occurs,
the low-level circulation center is expected to intensify, as well.
Moist isentropic ascent with modest active frontogenesis will present
enough forcing to support an expanding region of rain across most of
Southeast Michigan overnight tonight into early Thursday.
Expectations are for a widespread convective response south of the
state, which will limit the moisture transport up the frontal slope.
The RAP and GFS solutions offer some support for elevated
instability as far north at the M-59 corridor. The very modest
destabilization above the frontal slope should serve to at least
invigorate embedded showers in the rain shield.
Much of the deep forcing will wash east of the region by mid-morning
Thursday. The remnant low-level frontal zone will serve as a focus
for moisture collection - which will maintain clouds across the area
through much of the day (the exception being the Saginaw Valley
where late day clear is more likely). The clouds will limit the
temperature climb, with highs in the upper 50s (possibly eclipsing
60 across the Saginaw Valley).
Uneventful weather is expect Friday as weak northeast flow and
lingering lower clouds continue to keep surface temperatures
An upper low swinging southeastward through Ontario over the
weekend will bring a chance of showers to SE Michigan Saturday
afternoon through Sunday. Temperatures will be seasonably mild
through the weekend with highs in the mid to upper 60s. As the upper
low moves into the Northeast ridging will build into the Great Lakes
early next week. The 12Z ECMWF indicates a more amplified ridge
bringing drier, milder conditions to Lower Michigan early next week.
The GFS and CMC solutions favor a flatter ridge with disturbances
riding along the ridge axis through Lower Michigan early next week.
For the time being will keep shower chance in the forecast as warmer
air noses into the region with highs reaching the low 70s by Tuesday.
A stalled front across the Ohio Valley will provide the main focus
for showers tonight into Thursday as a low pressure system tracks
along it. A second weakening system will be tracking through the
Central Great Lakes during the same time helping to spread showers
northward into southern Lake Huron. Overall winds will remain
easterly and less than 15 knots through Thursday night before
backing more northerly for the weekend. A weak trough of low
pressure will linger over the region through the weekend though
marine conditions will remain fairly quiet through that stretch.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
You can obtain your latest National Weather Service forecasts online
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1009 PM CDT Wed May 10 2017
An isolated severe supercell thunderstorm that crossed the border
just southeast of Del Rio and has tracked east down Highway 90
produced at least quarter size hail (and likely significant hail
sizes in excess of 2 inches based on radar). This storm has held
together into Uvalde County, but a few runs of the HRRR that have
best handled this cell show that it will weaken and dissipate
somewhere between Uvalde and Hondo. Aircraft soundings within the
last hour from SAT show a fairly stout cap remains in place at 800
mb and CG lightning continues to trend downwards, so this forecast
seems reasonable. Thus, we have updated POPs to reflect this cell
tracking along the Highway 90 corridor, maintaining 20 POPs in San
Antonio in the unlikely occurrence that this cell is able to hold
together into Bexar County.
Another supercell located 30-40 miles to the southwest of Del Rio is
likely producing severe hail at the current moment. Although SPC
Mesoanalysis shows that some convective inhibition is developing in
this area into the Rio Grande Plains, the 00Z sounding at DRT was
rather unstable with 2400 J/kg of CAPE and minimal CIN. Model
soundings indicate that the atmosphere should stabilize between
10pm-1am in the Rio Grande Plains, but this storm should be able to
cross the border and maintain itself before it gradually dissipates
near the Highway 90 corridor in our western counties (potentially
over the same areas that already had one round of hail today). Water
vapor imagery also shows a shortwave moving into the region, which
combined with 35 knots of sfc-3 km shear and 60+ knots of sfc-6 km
shear evident on the 00Z DRT sounding, should be more than enough to
maintain the supercell for a few hours before it weakens. SPC
Mesoanalysis also shows SRH values of 200-300 m^2/s^2 over these
areas, so a tornado cannot be completely ruled out with this storm.
Once that cell weakens, the main show into the overnight hours for
the Edwards Plateau and perhaps the far western Hill Country will be
the convection that is currently developing along a retreating
dryline to our west between Fort Stockton and Ozona. These cells will
continue to develop over the next few hours and potentially merge
into a complex moving east-southeast. Model trends are generally
showing that this convection will weaken prior to entering our CWA,
but with the shortwave forcing aloft felt it would be prudent to keep
30-50 POPs showing that this convection. Although this convection
should not make it into the Interstate 35 corridor and the Coastal
Plains, isolated showers may develop just before sunrise, so we have
maintained 20 POPs there. Thunderstorm chances tomorrow afternoon
will depend on where any remnant outflow boundaries set up along with
the position of the weak front expected to move through the region,
but we are still expecting isolated to scattered showers and
thunderstorms (with a marginal risk of severe thunderstorms). More
updates on the severe potential for tomorrow will be given in the
Midnight shift`s forecast package.
.PREV DISCUSSION... /ISSUED 638 PM CDT Wed May 10 2017/
00Z Aviation Update Below.
VFR conditions prevail early this evening across South Central Texas.
Of immediate concern are TSRAs crossing out of Mexico near DRT.
These TSRAs have the potential to impact DRT now through 02Z with
gusty winds. Can not rule out some small hail, although not indicated
in the TAF. Kept mention of VCTS in the DRT TAF through 04Z in case
upstream convection re-develops along the higher terrain of Mexico.
Additional, a broken line of storms may try to develop after 06Z
between SJT and DRT, however these storms are expected to stay north
of DRT and also weaken early Thursday morning before reaching
portions of the Hill Country and Central Texas.
MVFR ceilings will develop SAT-AUS and through the Hill Country
02Z-06Z. Some indications that IFR ceilings may develop at SAT an
portions of the Hill Country closer to 12Z. Isolated to scattered
SHRAs may also develop through this region early Thursday morning and
expand northeast and east through the day. A few TSTMs can not be
ruled out. VFR conditions developing after 18Z.
SE winds currently 10-15 kts at many areas, with gusts 20-25 kts out
toward DRT. Winds will decrease overnight to around 5-10 kts and may
turn N to NE at DRT around 09Z-12Z.
PREV DISCUSSION... /ISSUED 309 PM CDT Wed May 10 2017/
SHORT TERM (Tonight through Thursday Night)...
Isolated convection is already being observed along the dry line
located from San Angelo through central Val Verde county but still
west of Del Rio. This area is characterized by surface dewpoints
around 70 degrees, low level flow out of the southeast convergent to
the dry line, an uncapped environment and SBCAPE values over 4000
J/KG. Satellite trends are showing updrafts are having difficulty
staying upright with very strong winds, near 100 kts, aloft. A speed
maximum at 500 mb is currently aiding in the lifting in the mid
levels however. Thus, updrafts will be battling with a lack of
consistent upper level forcing and should stay quite isolated along
the dry line through the afternoon. However, very large hail will be
the biggest concern with all the instability available in this area.
Damaging straight line winds are also possible as DCAPE values over
1000 J/KG were analyzed in RAP proximity soundings.
Later this evening, a combination of better upper level forcing
coincident with the dry line and an intensifying LLJ will allow
convection to develop around the 02-04Z time frame according to hi-
res models. Rapid growth due to the aforementioned unstable
environment will further the threat for large hail and damaging
winds along the dry line while these cells organize into clusters
and begin to shift eastward. As this occurs, TTU-WRF and HRRR
solutions agree on producing a stout cold pool and producing outflow,
eventually weakening the surface based storms as they approach the
periphery of the Edwards Plateau near Junction and Kerrville.
By tomorrow morning, elevated showers and isolated storms will
likely still be lingering across the Hill Country along outflow from
the overnight activity and may act as the focus for afternoon
development again. Meanwhile, the dryline is progged to push farther
east as the main upper low weakens and broadens over the Red River
Valley. As the low continues to push off to the east, it should take
PoP chances with it by tomorrow night.
LONG TERM (Friday through Wednesday)...
Dry conditions will linger through the weekend as H5 ridging sets up
over the state. Afternoon RH values will fall into the 20-30 percent
range and may result in elevated fire weather conditions, especially
Friday as the surface pressure gradient yields 10-20 kts winds across
the Plateau. Next opportunity for PoPs appears to be late Sunday as
another dry line sets up over West Texas and afternoon dry line
convection becomes a possibility. Another H5 low from the Pacific
northwest will eject energy over the region through the majority of
the week thus low PoPs have been included just about each afternoon
for western areas near the dry line.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 71 84 65 85 61 / 20 30 20 0 0
Austin Bergstrom Intl Airport 70 84 65 84 59 / 20 30 30 0 0
New Braunfels Muni Airport 70 84 65 86 59 / 20 30 20 0 0
Burnet Muni Airport 68 82 60 81 56 / 40 30 20 0 0
Del Rio Intl Airport 69 90 64 89 62 / 60 10 0 0 0
Georgetown Muni Airport 70 83 62 83 58 / 30 30 30 0 0
Hondo Muni Airport 70 85 64 89 58 / 30 30 10 0 0
San Marcos Muni Airport 71 84 65 85 59 / 20 30 20 0 0
La Grange - Fayette Regional 71 85 68 85 60 / 20 30 30 - 0
San Antonio Intl Airport 70 84 67 87 61 / 20 30 10 0 0
Stinson Muni Airport 71 85 67 87 62 / 20 30 10 0 0
Public Service/Data Collection...33
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
857 PM CDT Wed May 10 2017
We continue to watch a large upper trough over New Mexico, with a
surface dryline now slowly retreating west toward the better height
falls over the Texas Panhandle. A lead shortwave disturbance was
lifting east with an upper jet maximum from the Big Country toward
southwestern Oklahoma. Several storm or storm clusters were noted
on regional radar. A large cluster was occurring across west
central Oklahoma, with another cluster between San Angelo and
Abilene, to more isolated thunderstorms along the Upper Rio Grande
Valley near Del Rio.
Per the latest 00Z FWD sounding, there was a weak capping inversion
anchored near 700mb. As an earlier storm over Stephens County
progressed east, it died pretty quickly. With the larger upper
low expected only to shift east slowly and a strengthening capping
inversion expected over the eastern two-thirds of North Central
Texas, have confined storm chances northwest of a Comanche-
Mineral Wells-Gainesville line through midnight. A severe threat
for large hail, damaging winds, and possibly an isolated tornado
cannot be ruled out west of a Cisco to Nocona line.
Left best storm chances west of I-35/35W after midnight as 18Z
runs of high-resolution models are struggling with the complexity
of this large upper level system. We are still awaiting 00Z runs
of these models. For now, do expect isolated to scattered
thunderstorm chances across areas especially along and west of
U.S. 281 overnight, where large-scale ascent associated with mid
level height falls will be maximized and able to overcome the
weak, elevated capping inversion aloft. Strong to severe storms
will be possible from the pre-dawn hours through sunrise across
this area. Otherwise, made minor tweaks to hourly moisture, wind,
and sky cover.
/ISSUED 716 PM CDT Wed May 10 2017/
The convective activity that affected the TAF sites this afternoon
has now moved into East Texas. A lone thunderstorm cluster in
western North Texas has been struggling to maintain its intensity
as it enters the FWD CWA. The 00Z RAOB from FWD showed that the
cap had lifted and weakened but remained around 700mb. The
unstable atmosphere across the Big Country was largely uncapped
at peak heating, but short-range guidance suggests that the
inhibition in the vicinity of the ongoing activity is steadily
increasing already. And with the loss of daytime heating, this
stabilizing process should only intensify. As a result, this
cluster should steadily weaken this evening.
Southeasterly 850mb flow above the Rio Grande will force the
dryline to retreat into the Pecos Valley this evening as a
shortwave swings overhead. Consensus among mesoscale guidance is
for this portion of the surface boundary to light up later this
evening. The mean flow would quickly separate the cells from the
dryline, spreading them northeast across the Concho Valley and
into North Texas during the predawn hours. Although the initial
updrafts may be rooted in the boundary layer, the activity will
transition to elevated showers by the time it reaches the I-35
corridor around daybreak Thursday morning. This convection, which
should pose minimal impacts, will pass north and northeast of our
TAF sites by late morning.
As an upper low ejects through the Panhandle and into Oklahoma on
Thursday, the mid-level flow will veer, forcing the dryline into
North and Central Texas. The surface flow will veer in kind, and
although the I-35 corridor will likely still be on the humid side
of the boundary when convective initiation occurs Thursday
afternoon, the resulting thunderstorms may be to the east of all
TAF sites. There could be considerable disruptions to east
departures and arrivals through Bowie and Cedar Creek, but the
potential for impacts at our terminals still appears too low to
include in the TAFs at this time.
A cold front will arrive Thursday evening, potentially as late as
midnight as the current public forecast shows. Have introduced
this wind shift into the extended portion of the DFW TAF and will
fine-tune the timing with subsequent issuances.
.PREV DISCUSSION... /ISSUED 342 PM CDT Wed May 10 2017/
Mid-afternoon moisture channel imagery depicts the presence of a
jet maxima impinging upon our western-most counties, and
associated isentropic upglide along the 305-315 K theta surfaces
appears to be responsible for the earlier convection across our
forecast area. The strongest of this activity has migrated
north across the Red River, leaving us with lingering high-based
showers and occasional thunderstorms. As the aformentioned jet
streak continues to press eastward, associated ascent may be
sufficient to spark off additional isolated thunderstorms through
the remainder of the afternoon and early evening. Recent ACARS
soundings reveal that stout capping observed on this morning`s
KFWD sounding generally remains in place, as southwesterly mid-
level flow has continued to advect +15 to +16 C air across North
and Central Texas. As a result, any additional convection
associated with the aforementioned isentropic ascent/WAA this
afternoon may struggle to fully realize its thermodynamic
potential as updrafts encounter multiple stable layers from 850 mb
and upwards. That said, the more rambunctious updrafts will be
capable of producing nickle to perhaps marginally severe hail.
The main area of concern regarding a more impactful severe weather
threat continues to be across our western counties, in the
immediate vicinity of the dryline. Currently, this feature
stretches from near a San Angelo to Sweetwater line, before
curling northwestward into a surface low just southeast of Floydada
in the Texas Panhandle. One updraft has initiated near the surface
low/dryline/outflow intersection, and visible satellite imagery
reveals a recent uptick in agitated cumulus farther south along
the dryline just west of Abilene. The presence of some stable wave
clouds, however, indicates that inhibition has not fully eroded.
The combination of dewpoints in the lower to middle 60s and air
temperatures in the upper 80s is resulting in rapidly eroding
convective inhibition in this region, however, and this is
confirmed by RAP point forecast soundings. As a result, convective
initiation may not be far away now along this boundary, and this
idea is supported by recent runs of the HRRR/HRRRX. Should storms
manage to mature and move off the dryline, they would mature into
a kinematic/thermodynamic environment conducive for supercells.
The main threat with any isolated storms that initiate on this
boundary would be large hail (golf ball sized) given steep mid-
level lapse rates and plentiful amounts of CAPE in the hail growth
zone, and deep layer shear values in excess of 50 kts, with a
secondary threat of damaging wind gusts. The tornado threat
appears LOW, but one cannot be ruled out, mainly closer to the
surface low across our far northwestern counties this evening. To
reiterate, any coverage looks to remain isolated at worst as
storms move northeast. The main area of concern continues to be
along and west of US-281 and towards Bowie.
Any storms that develop on the dryline should begin to wane later
this evening as nocturnal inhibition grows. However, there
continues to be a strong signal from coarse and high-res guidance
alike that additional--likely elevated--convection will develop
along the retreating dryline across the Concho Valley late this
evening. It appears the forcing mechanism for this activity would
be from a shortwave presently pivoting out of Mexico and into the
Trans-Pecos region of southwestern Texas. This activity is
expected to press north and eastward, and may move into our
western counties during the 2-5AM time frame. Given the presence
of continued steep mid-level lapse rates and 40-50 kts of
effective bulk shear, large hail would be the primary threat, even
as storms gradually begin to weaken. The main area of concern is
west of a Bowie to Mineral Wells to Stephenville to Lampasas line.
This activity should continue to press northeastward, perhaps even
into the DFW metroplex towards daybreak on Thursday, but
anticipate that any lingering activity by that time will have
weakened below severe limits. Depending on how long this activity
lingers, it may impact our ability to destabilize Thursday
afternoon ahead of the incoming dryline/cold front.
The current thinking at this time is that this activity will
dissipate by the mid-morning hours on Thursday as it outruns the
axis of higher elevated instability. Most of the day then may
actually be pretty quiet as we wait for buoyancy to build up and
for temperatures to warm sufficiently to breach the cap. As we
wait, the dryline will surge eastward and its ultimate location as
CINH finally erodes during the mid to late afternoon will dictate
where the greatest severe threat will exist. Our best estimate is
that it will be draped from near a Gainesville to Weatherford to
Lampasas line by mid afternoon. Locations south and east of the
dryline`s location will be under the gun for severe storms as
parcels finally manage to breach their LFCs, sometime around 3-5
PM, and this includes the Metroplex. We must note that if the
dryline surges farther east than anticipated, the severe threat
will subsequently shift farther east as well.
Thunderstorms should grow rapidly and into an environment once
again supportive of supercells capable of producing large hail and
damaging wind gusts. The tornado potential still appears LOW since
low-level winds look to veer fairly sharply ahead of the dryline,
and 0-1km shear values remain under 15 kts or so. As the evening
wears on, storm clusters may congeal into a linear complex as this
activity moves to the east. As upscale growth into a QLCS occurs,
the primary severe threat may begin to shift towards damaging
straight line winds (but large hail will remain a threat). While
still LOW, the tornado threat may increase slightly during the
evening as activity tracks into our eastern and southern zones and
0-1km flow increases. Thus, we cannot rule out a tornado or two
during this time as storms trundle out of our forecast area.
Most, if not all, of the severe threat should be out of our region
shortly after midnight Thursday night, but the surface cold front
will take several more hours to fully sweep through the region.
This will scour us out, leaving us with a very pleasant Friday and
upcoming weekend. Moisture will rapidly re-enter the picture early
next week, resulting in the return of low thunderstorm chances
Monday through Wednesday.
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 69 85 64 79 59 / 20 30 20 10 0
Waco 68 83 64 81 57 / 20 30 30 10 0
Paris 65 79 62 76 56 / 20 70 70 10 0
Denton 67 86 62 78 54 / 30 30 20 10 0
McKinney 67 84 63 77 56 / 20 50 30 10 0
Dallas 69 85 64 80 60 / 20 30 30 10 0
Terrell 67 82 63 78 57 / 20 50 50 10 0
Corsicana 68 81 64 80 58 / 20 40 40 10 0
Temple 68 83 63 82 57 / 30 30 30 10 0
Mineral Wells 65 88 61 79 54 / 40 20 10 10 0
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1041 PM EDT Wed May 10 2017
Issued at 1041 PM EDT WED MAY 10 2017
The evening update to the forecast package resulted in lowering
of overnight temperatures. Surface observations, including
Kentucky Mesonet stations showed temperatures approaching
advertised lows in several spots, most notably and to no surprise
our valleys areas. Was tempted to increase PoPs across the north
towards dawn with current movement of upstream convective system.
But higher resolution models, and in particular the HRRR has been
back and forth with southern most extent of activity. Left
inherited PoPs in place for now but will reevaluate before end of
shift. Should more widespread activity actually make it into our
area, timing would put the bulk of convection across our
northeastern counties between about 4 and 8 a.m.
UPDATE Issued at 653 PM EDT WED MAY 10 2017
Updated grids to bring them in line with hourly trends. Complex of
storms appears to affect portions of the area late tonight or
during the pre-dawn hours Thursday. The bulk of convection
associated with this system currently moving through the Midwest
looks to shift just to our north and east but may provide a
glancing blow to several of our northeastern counties. Current
forecast has this handled well.
.SHORT TERM...(This evening through Thursday night)
Issued at 349 PM EDT WED MAY 10 2017
Current conditions across the area feature a boundary still across
northern Kentucky but also showing no real movement. In fact
development has been nil with any showers far to the north over
OH. Have lessened pops over the north and dropped the mention of
strong storms tonight as development will be slight chance at
best. Also dropped the sectioned HWO for this. It appears any
possible development into eastern Kentucky will rely on a
developing MCS moving into IL. This should eventually drop
southeast into northern KY tonight and also skew the boundary with
further development south into southeast KY by dawn.
This feature should set the stage by moistening the boundary
layer in the morning while still allowing enough time through the
morning for destabilization. Another wave will move east over the
ridge positioned over the southeast and into Kentucky by Thursday
afternoon. This feature will have some strong mid level winds with
decent shear setting up in the afternoon and Thursday evening.
Thus have mentioned a wind threat as well as a heavy rain threat
in the HWO. This is in addition to through the day on Friday as
the cold front finally pushes east. While The main severe threat
will be on Thursday afternoon through Thursday night the multiple
rounds of storms and PWATs in the 1.20 to 1.40 range through
Friday afternoon will pose the threat for flooding. Have mentioned
this in the HWO and passed this information onto the evening
shift for possible Flood Watch consideration.
.LONG TERM...(Friday through Wednesday)
Issued at 300 PM EDT WED MAY 10 2017
A shortwave trough will eject out across the region on Friday with
Showers and a few thunderstorms overspreading the area by midday
and through the afternoon and evening hours. This is shaping up
to be the wettest day of the week for most of the area. Best
instability will be tied up across the southern half of Kentucky,
with very little instability to the north. SBCAPE will approach
2000J/KG. Shear is weaker, but sufficient for a few strong storms
late in the morning or early afternoon. Main threat would be a few
strong wind gusts. Precipitation will come to an end overnight
Friday night with a cooler and less humid airmass settling in for
the upcoming weekend. Mid level ridging will then slide east
across the area over the weekend, setting up a very pleasant
weekend. As the ridge axis slides east of the region early next
week, return flow will allow for rebounding temperatures back into
the 80s. However, the weather should remain dry through Tuesday.
Its possible by Wednesday that enough moisture may recover to
allow for an isolated shower or storm, but this far out confidence
is low on this idea and will maintain a dry forecast.
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 653 PM EDT WED MAY 10 2017
Frontal boundary lays west-northwest to east-southeast across the
area this evening, stretching roughly from around CVG to HTS.
Only convection showing up are some isolated cells closer to the
boundary, well outside of our forecast area. HRRR model solution
has been hinting at the potential of a complex of storms sliding
southeast overnight, providing a glancing type blow to the
northeastern third of our forecast area. This would affect mainly
SYM and SJS, and possibly JKL if things played out accordingly.
Will keep an eye on things through the evening to narrow down
timing. At present it seems most likely convection might move into
these areas towards dawn with the bulk of convection further off
to our north and east, generally along and north of the frontal
zone. Winds will be southerly and generally light through the
overnight, but then pick up to between 10 and 15 kts Thursday with
a few gusts to around 20 kts.
Area Forecast Discussion
National Weather Service San Angelo TX
621 PM CDT Wed May 10 2017
A dryline is located west of all terminals and in now retreating
slowly to the west early this evening, with all terminals now
VFR. VFR conditions should prevail at all terminals for the
remainder of the evening. A pacific front will push the dryline
back to the east after midnight with a chance of showers and
thunderstorms into the early morning hours. For the terminals,
the best chance for thunderstorms and VCTS should begin around
midnight for the western terminals lasting for a few hours, and
beginning a few hours later for the KJCT and KBBD.
.PREV DISCUSSION... /issued 323 PM CDT Wed May 10 2017/
(Tonight and Thursday)
Dryline has slowly moved into the western portions of the area this
afternoon, running roughly from a Hamlin to San Angelo to Ozona line
at 3 PM (20Z). Dryline shouldn`t move much farther east this
afternoon, and then should begin to retreat back west this evening.
Convection has developed along the triple point across the Southern
Plains east of Lubbock, where strong instability and good shear has
led to the issuance of a Tornado Watch that includes the Northern
Big Country of Haskell and Throckmorton. Brunt of the convection
will likely remain near the triple point and outflow boundary across
the Red River, but better convergence along the dryline and a speed
max moving into the area should lead to a few storms down the
dryline this afternoon and evening, perhaps as far south as Haskell
Farther south...additional convection has developed across Val Verde
County, with satellite showing decent cu developing up the dryline
to near San Angelo and Abilene. This area is largely being bypassed
by the speed max to the north at the moment, and is mainly dependent
on the dryline itself to initiate convection. Isolated to scattered
storms possible along the dryline this afternoon and evening, but
does not appear to be terribly widespread. All this changes later
this evening, when the approaching cold front overtakes the dryline.
Low level jet cranks up as well and the latest HRRR and TTU WRF both
show a large area of convection developing across the western
portions of the Concho valley and Edwards Plateau late this evening.
Right rear quad of the jet becomes a factor, and with good elevated
instability, convection should become more widespread. Have increased
PoPs a little for tonight mainly west of an Abilene to San Angelo to
Ozona line. Convective coverage should be maximized during the
overnight hours, and start to wane a little into the first half of
the day on Thursday as the storms move into the Northwest Hill
(Thursday Night through Saturday Night)
A quiet weather pattern is expected late this week into the first
part of the weekend as weak surface high pressure along with a low
level dry airmass is centered over much of Texas. Highs will be in
the upper 70s to lower 80s Friday and 80s on Saturday. Lows will be
in the 50s.
(Sunday through Wednesday)
A more active and unsettled weather pattern is in store across the
Southern Plains early to middle of next week. Looking at a more
typical May pattern with an upper level trough across the western
US, sending disturbances northeast in the southwest flow aloft. At
the surface a dryline will be located just to our west, and will
probably move east into our area during the afternoon hours. As a
result going with slight chance to chance Pops through much of this
period. The combination of moderate instability and good effective
deep layer shear will probably result in at least a few storms
becoming severe, especially Wednesday. However, talking about
details(like mesoscale) is still to far out, but West Central Texas
is now in the peak of severe weather season.
.PRELIMINARY POINT TEMPS/POPS...
Abilene 60 88 56 79 / 40 10 5 0
San Angelo 61 89 58 81 / 50 10 5 0
Junction 64 87 57 82 / 50 30 10 0
Brownwood 62 87 58 79 / 50 20 10 0
Sweetwater 58 87 55 77 / 30 5 5 0
Ozona 59 87 57 81 / 50 10 5 0