Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/10/17
Area Forecast Discussion
National Weather Service Hastings NE
659 PM CDT Wed Aug 9 2017
.UPDATE...
Issued at 609 PM CDT Wed Aug 9 2017
Updated the forecast this evening to increase chance of rain near
broken line of showers/thunderstorms and closely timing to the
latest movement of the line. The line is experiencing general
decay as the sun gets closer to setting. Increased sky cover near
the proximity of the storms as well.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 202 PM CDT Wed Aug 9 2017
A cold front is currently located just to the northwest of the
CWA. This front is expected to be the focus of thunderstorm
development over the following few hours. The HRRR has been very
consistent developing a line of storms and moving it southeastward
across the area through the early evening. I expect that this
line will gradually weaken later in the evening as instability
wanes a bit. Speaking of instability, RAP soundings show
1500-2000J of sfc-based CAPE. Coupled with around 25 kts of 0-6km
bulk shear, storms will be supportive of marginally severe hail
and up to 60 mph wind gusts...especially if storms develop into a
well-defined line.
Thunderstorms should clear out of the area by around midnight at
the latest. After that, we are looking at a decent potential for
fog development into Thursday morning. There is some question on
how well we will clear out, but the HRRR and SREF are both hinting
at lower visibilities, so I`ve continued the forecast of patchy
fog across the area.
Later Thursday afternoon, another cluster of thunderstorms is
expected to develop over the High Plains, mainly affecting the
southwestern half of the CWA into the evening and overnight. A
strengthening upper level jet will lead to higher bulk shear
values than today...on the order of 40 to 50 kts. With a corridor
of 2000J of MUCAPE present according to the NAM, strong to severe
storms are a threat once again.
.LONG TERM...(Thursday night through Wednesday)
Issued at 202 PM CDT Wed Aug 9 2017
Thunderstorm chances will gradually diminish Thursday night into
Friday morning, before returning from the west Friday night as a
compact wave moves through the area.
The model blend has PoPs lingering across the entire area through
the day on Saturday as additional thunderstorms will likely develop
on remnant boundaries. That said, I think that there will be
significant dry time after the overnight convection moves out of the
area, but it is hard to pinpoint timing enough to have any 6-hour
dry periods.
Off and on rain and thunderstorm chances continue Sunday and Monday
as the main trough and enhanced upper level jet continue to impact
the area. These features will gradually move east of the area Monday
night into Tuesday. While we don`t have a completely dry forecast
for these time periods, I think that it will mark a transition to a
somewhat drier pattern through the middle of next week.
Thanks to northwesterly flow aloft, temperatures will continue to
be below normal. In fact, high temperatures are expected to stay
out of the 90s for the entirety of the forecast period. Look for
this to change as we move into increasingly zonal flow by the
latter half of next week.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 658 PM CDT Wed Aug 9 2017
Main issue will include departing showers/storms at the very
beginning of the forecast, perhaps a bit lower ceilings, but still
VFR. Then lowering vis later tonight.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
UPDATE...Heinlein
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Goodland KS
751 PM MDT Wed Aug 9 2017
.UPDATE...
Issued at 745 PM MDT Wed Aug 9 2017
Just completed an update. Initial adjustment was to cut back on
sky cover this evening per latest satellite. One of the twp main
changes was for later tonight for the increasing of pops and the
coverage of fog. Models are clustering now, rap and especially the
Hrrr which was not earlier and has been doing well lately, of
bringing in a cluster of thunderstorms into the forecast area
after midnight. So increased the pops in that area, and if trends
continue they may need to be increased more.
Second change was to increase the coverage and westward extent of
the fog. Models are not as aggressive in bringing precipitation
in from the southwest with most of the area being precipitation
free until above mentioned cluster arrives later tonight. Rap and
Hrrr are in great agreement on this, especially for the southeast
third to half of my area, and increased accordingly. Also if they
are right, we may need a dense fog advisory later tonight.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 230 PM MDT Wed Aug 9 2017
A weak cold front extends across the center of the forecast area
from northeast to southwest early this afternoon. Latest short term
models are suggesting that showers and thunderstorms will quickly
develop and possibly become severe along the frontal boundary,
primarily across the eastern 1/2 of the area. Locally heavy rainfall
also possible. This activity should be east of the area before
sunset, however will have to then watch our Colorado counties for
thunderstorms that move in after 7 pm mdt or so from the front
range. These should end by midnight.
For the overnight hours models are in pretty good agreement bringing
another rather healthy weather disturbance across the area from the
northwest. Precipitable water increases into the 1.2-1.5 inch range
with some upper jet divergence along with it. NAM/GFS qpf looks in
reasonable agreement timing wise but the hrrr (which has done rather
well with timing and placement/intensity the past several days) is a
little faster bringing it through and not showing near the coverage.
Will keep precip chances in the slight chance to low chance range
for now.
Any precipitation around sunrise should exit the area by mid to late
morning and we could be in a lull for several hours until the next
one or two weather systems move in from the northwest bringing
increasing chances for strong to severe thunderstorms in the
afternoon. Currently expecting high temperatures in the upper 70s to
mid 80s. We may have temperatures falling in the afternoon
depending on timing/arrival of the clouds and precipitation.
.LONG TERM...(Thursday night through Wednesday)
Issued at 230 PM MDT Wed Aug 9 2017
The forecast will continue to be active, with chances for rainfall
mainly during the night as upper level short wave troughs in the
northwest flow move over the forecast area.
Thursday evening chances for rainfall will increase as the upper
level short wave trough deepens over the Tri-State Area. Currently
looks like most of the forecast area will have a good chance for
receiving rainfall. However, the southwest quadrant of the
forecast area may have a flash flood threat due to the slow
movement of the upper level short wave trough overhead and the
very high rainfall amounts the NAM/GFS/MOS are generating over
that same area. This area has already RECEIVED quite a bit of
rainfall recently, which further increases the risk for flash
flooding. If the data looks similar tomorrow, a watch may be
needed.
Regarding severe weather for Thursday evening, this will greatly
depend on the speed of the front. If the front moves through
faster, it should be through the forecast area by early evening with
the severe weather threat to the south. If the front moves through
later in the afternoon the threat for severe weather may extend into
the evening. With the surface low forecast to be over the TX/OK
panhandles Thursday afternoon/evening, this setup favors a faster
frontal passage. Based on this would side with the earlier frontal
timing which would limit the amount of severe weather that would be
possible in the evening.
During the overnight hours the weather should be dry as subsidence
moves in. Fog does not look as favorable as mentioned in the
previous discussion due to lower probabilities of fog now forecast.
However with recent rainfall, very light wind and a surface high
nearby would create a favorable environment for fog to form. Kept
in a mention of fog where it is most likely to occur.
Friday rainfall chances shouldn`t move into the forecast area until
the late afternoon another upper level short wave trough approaches
from the northwest. The best chance for rainfall will be during the
night as the upper level short wave trough moves through. There is
some disagreement as to when the bulk of the rainfall will be,
either during the evening or overnight. There is a potential for
severe weather in the evening as the short wave trough moves through.
Saturday looks more like a setup for drizzle and elevated
thunderstorms as a backdoor cold front moves through. The
environment will be dry except for the first few thousand feet above
ground. With weak isentropic lift occurring, drizzle may occur. In
addition the weak lift and low elevated CINH may allow thunderstorms
to form. Deep layer shear and elevated CAPE would be supportive of
supercell thunderstorms. During the night another upper level short
wave trough moves through, bringing another round of rainfall with
it.
Sunday through Wednesday chances for rainfall will continue for the
entire forecast area as upper level short wave troughs continue to
move through. The best chance for rainfall will be midweek when a
strong upper level short wave trough moves through.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 521 PM MDT Wed Aug 9 2017
For Kgld, vfr conditions are expected at this time. Complicated
forecast with models showing a number of possibilities for
thunderstorms through the night. Models have been trending toward
bringing in a cluster of storms later tonight toward 12z. So chose
to add vcts at this time and will refine later. Better chance of
thunderstorms looks to happen later in the day and felt confident
enough to add vcts near 21z. Winds will remain light and variable
to light to least easterly.
For Kmck, vfr conditions are expected until 09z. At this time fog
is expected to develop and bring mvfr conditions to the site
through 15z. As with kgld, chose to add vcts in the afternoon
around 20z since chance looks pretty good. Winds will be light and
variable to light east to northeast.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...99
LONG TERM...JTL
AVIATION...BULLER
Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
939 PM CDT Wed Aug 9 2017
.UPDATE...
Scattered thunderstorms stretching from northeast New Mexico into
the west- central Texas Panhandle continues to propagate slowly
southeastward this evening. This activity will be moving into air
characterized by greater convective inhibition and decreasing
instability with southeast extent, but it will also encounter a
southerly LLJ jet that will increase into the 20-30 knot range
later tonight. Given this and recent HRRR runs (and to a lesser
extent the RAP) there appears a decent bet isolated to scattered
convection will make it into the northwestern zones over the next
few hours before diminishing early Thursday morning. Given this,
we have raised PoPs into the high chance category over the
northern parts of Parmer, Castro and northwestern Swisher Counties
for the remainder of tonight. We have maintained a sharp cutoff
of mentionable PoPs across the northern South Plains with the
expected demise of the t-storms late tonight. The remainder of the
forecast is in good shape with only minor adjustments made in the
near-term.
&&
.PREV DISCUSSION... /issued 626 PM CDT Wed Aug 9 2017/
AVIATION...
VFR conditions are expected through the forecast period. The only
fly in the ointment is TS moving out of northeastern New Mexico.
Some hi-res model solutions hold them together approaching KCDS
and KPVW shortly after 06z. The HRRR in particular is showing this
and has performed well the last two nights. Have kept out for now
given the uncertainty but certainly worth watching through the
evening.
PREV DISCUSSION... /issued 333 PM CDT Wed Aug 9 2017/
DISCUSSION...
The remnants of a small MCS/MCV which passed across the South
Plains this morning was still apparent in satellite imagery over
the southeast Rolling Plains, and heading southeast. The airmass
across the area has been stabilized in the wake of this feature,
with the 20 UTC surface analysis showing the theta-e ridge
extending northward in eastern NM before bending northeast into
the northwest TX and OKLA Panhandles. Thunderstorm development
will occur in that area this afternoon and evening, and
especially around the Raton Mesa where a weak cold front
intersects the elevated terrain. A 30 kt srly LLJ will develop
across the southern plains late evening so we expect storms to
consolidate into another small t-storm complex and propagate sewd
toward the CWA. Reflectivity/QPF signals are not as robust as last
night however, and we`ve confined PoPs to roughly the northern
1/3 of the forecast area with expectations that the MCS will
dissipate before making much progress into our area.
The upper-level ridge is still forecast to temporarily build
across west-central TX tomorrow into Friday and should keep the
t-storm activity mainly to our north, although there will be a
chance both Thursday and Friday nights that an MCS rolling across
the panhandles could clip our northern counties.
It still appears that rain chances will be on the rise for the
weekend. Those nocturnal MCS`s will help push/augment the front a
little farther to the south Saturday - which will then provide a
focus for t-storm development Saturday afternoon and evening as a
shortwave moves across the plains. The exact timing and details of
these features are still not set in stone, but by Saturday
evening, model QPF signals increase quite a bit across the area.
Additional shortwave energy moving through the plains Sunday
through Tuesday should keep the upper ridge suppressed to the
southwest, with a northwest flow pattern and deep moisture
supporting continued rain chances through the period. One of the
big questions is where the front will be located during this time.
As we saw last weekend, if the front/outflow gets pushed too far
south, that might curtail our rain chances as some point. Overall,
this pattern appears to support potential for some heavy rain of
several inches, maximized across our northeast, but we will hold
off on any highlights in the HWO for now to see if the forecast
pattern is consistent.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
07/23
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
924 PM EDT Wed Aug 9 2017
.SYNOPSIS...
A front will remain stalled just southeast of the area tonight
then lift north as a warm front Thursday. High pressure will
gradually ridge in from the east this weekend as a trough
lingers to the west. A cold front will move into the region
from the west early next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 920 PM Wednesday...Latest satellite loops and surface
observations show skies have clear over our far western and
northern CWA as drier air with dewpoints in the mid 60s and
precipitable water values under 1.5 inches has been able to inch
into that portion of the CWA. Deeper moisture lingers at the
coast, but all of the light precipitation is now offshore and
have scaled back PoPs, keeping only a slight chance along the
immediate coast through about 08Z. The latest HRRR and RAP
models do indicate a scenario similar to this morning when some
showers will move back north along the coast in the early
morning hours of Thursday and will continue a forecast of likely
PoPs immediate coast into mid-morning as warm front starts to
pivot back toward the north. Given wet ground from recent
rainfall, may see some patchy fog overnight with low- level
stratus. No changes needed to the temperatures with the mid to
upper 60s inland and lower 70s coast.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
As of 245 PM Wed...Front will slowly move back north into the
area as a warm front with possible weak low development along
it. Still looks like best precip chances will be along the
southern coast early, transitioning to more scattered coverage
in the afternoon. 12z guidance seems to be drier than previous
runs, but will keep high chance to likely pops along the coast
early (though this may end up being a bit overdone). Kept
slight chance thunder mention, though instability looks marginal
at best given widespread cloud cover and low level NE/E flow.
Forecast soundings show MU CAPE values increasing up to
1000-1500 J/kg and 0-6km shear 20-30 kt. Primary threat will
still be locally heavy rainfall with PWATs around 2 inches.
Below normal temps will continue given widespread cloud cover
and NE flow early. Highs in the upper 70s to low 80s.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
As of 300 PM Wed...Southerly flow will increase Friday and
continue into the weekend bringing increased moisture into the
area. Scattered showers and thunderstorms will breakout ahead
of a broad upper level trough through Sunday. Another cold
front will approach the region for the beginning of next week,
leading to another period of more widespread showers and
thunderstorms.
Thursday Night through Sunday...After the warm moves north of
the region Thursday night, summer like moisture and humidity
return to Eastern NC. Have at least chance PoPs across most of
the CWA for this period. Think showers and convection will be
diurnally enhanced each afternoon and evening, so have high
chance PoPs for these periods. High temps will be generally in
the mid/upper 80s inland, and the low/mid 80s along the coast as
there will be more clouds than sun. Low temps will be in the low
70s inland and the mid/upper 70s near the coast.
Monday through Wednesday...As a cold front approaches the region
Monday, more widespread showers and thunderstorms are likely to
develop. This will continue on Tuesday and into Wednesday as
the front slowly crosses through the CWA. Have high chance PoPs
through most of this period. As the upper trough moves over the
area, more favorable dynamics will be present to support more
organized thunderstorms. Also, we will continue to watch for the
possible development of a tropical cyclone off the Southeast
coast during this period, which would then travel up the coast,
however it will likely be well offshore. High temps on Monday
will be in the upper 80s to near 90 inland and the mid 80s near
the coast. On Tuesday and Wednesday highs will range from the
mid/upper 80s inland, to the low/mid 80s along the coast. Low
temps will mostly be in the low 70s inland and the mid/upper 70s
near the coast.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
Short Term /through 00Z Friday/...
As of 925 PM Wednesday...Skies have cleared at all but KEWN as
some drier air works into our western and northern CWA. With the
clearing, a wet ground from recent rainfall, and light NE winds,
will now forecast a period of IFR ceilings at all TAF sites
after 07z or 08z to around mid-morning Thursday. Ceilings
should gradually improve late Thu morning. Scattered showers and
isolated thunderstorms are expected Thursday.
Long Term /Thursday Night through Monday/...
As of 250 PM Wed...Mostly VFR conditions are expected in the
long term. There will be periods of sub-VFR conditions with
passing showers and convection, that will be possible each day.
Locations that receive rainfall during the day will be
susceptible to patchy ground fog overnight which will reduce
visibilities.
&&
.MARINE...
Short Term /through Thursday/...
As of 925 PM Wednesday...Trends in the guidance look good as
winds have continued to diminish across the coastal waters and
Sounds this evening, with only Diamond Buoy still gusting into
the upper teens. Seas continue at 2-4 feet, but will slowly
subside to 2-3 feet toward morning. Winds should start to veer
around to more SE/S on Thursday afternoon as stalled front
begins to drift back toward the north.
Long Term /Thursday Night through Monday/...
As of 255 PM Wed...Winds will be out of the S/SE around 10 kts
from Thursday night through Friday night. Then, winds slightly
shift to the SW/SSW 10-15 kts through Sunday morning. Then winds
become southerly around 10 kts. Seas through the period will be
mostly 2-4 ft.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...CQD
NEAR TERM...CTC
SHORT TERM...CQD
LONG TERM...SGK
AVIATION...CTC/CQD/SGK
MARINE...CTC/CQD/SGK
Area Forecast Discussion
National Weather Service Melbourne FL
837 PM EDT Wed Aug 9 2017
.UPDATE...
Tonight...East-west boundary collision produced isolated lightning
storms west of I-4 this evening. The activity was already
diminishing and the HRRR model does not show any additional
development.
A ribbon of subsidence/drying was shown on water vapor imagery
between axis of weakening upper level ridge across the area and
easterly wave approaching the Bahamas. The models show this drier
air aloft keeping POPs out of the forecast overnight, except
easterly low level flow may push a few Atlantic showers into the
Treasure Coast. No significant changes are planned to the previous
forecast.
Thursday...The 18z GFS trended wetter as the model showed
approaching easterly wave spreading higher moisture across southern
sections compared to its previous run. MOS POP values went up to 60-
70% in the south. This solution is closer to the wetter ECMWF,
though the GFS still shows ribbon of drier air holding on in the
north. Current forecast shows a POP range of 20-50% across the area.
This looks good for now so not planning any changes. Will let the
midnight shift have a look at the 00z run to see if the wetter trend
continues.
&&
.AVIATION...Mainly VFR as drier air aloft will overspread the area
overnight. There will be isolated showers over the Atlantic, but the
chance they will affect coastal terminals is too low to mention yet
in the TAFs. Higher moisture is forecast to spread across the
peninsula Thu, especially south of KISM-KMCO-KTIX. Therefore, have
mentioned vicinity showers/storms KMLB-KSUA.
&&
.MARINE...
Tonight-Thursday...High pressure to the north will provide an
easterly wind flow. Approaching inverted trough over the Bahamas is
forecast to remain weak, but could tighten the gradient for a time
to 10-15 knots. Seas will be around 2 feet at the coast and up to 3-
4 feet offshore. The trough will increase the coverage of showers
and storms on Thu, mainly from Cape Canaveral southward.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Forecasts...Lascody
Radar.......Sedlock
Aviation....Smith
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
812 PM CDT Wed Aug 9 2017
.UPDATE...
Area of showers/storms in N OK and S KS is expected to continue to
move SE across portions of the area this evening. Increased PoPs
to account for this activity. A few of the storms in N OK could be
strong to severe.
&&
.PREV DISCUSSION... /issued 634 PM CDT Wed Aug 9 2017/
AVIATION...
0Z TAFs - Several rounds of scattered showers/storms are possible
across portions of the area during this TAF period with the
highest chances in northern Oklahoma. Chances are currently too
low at some sites for mention in TAF. Gusty winds and heavy rain
will be possible with the storms.
PREV DISCUSSION... /issued 347 PM CDT Wed Aug 9 2017/
DISCUSSION...
Thunderstorms persist over northern Oklahoma and will continue
into the early evening. This is the first of what may be at least
two waves of storms. HRRR suggests the possibility of another
round of storms moving into northwest Oklahoma this evening,
although other models aren`t as aggressive with this. Then there
is a higher chance of storms in the morning hours with storms
moving in from Colorado and/or western Kansas. An even higher
chance of storms returns late tomorrow afternoon or tomorrow
evening as a storm complex is expected to develop in southern
Kansas or near the Oklahoma border and moving south/southeast
through the area with the highest precipitation chances northeast.
With the surface boundary lurking north of the area, west-
northwest flow aloft, and various shortwaves moving into the upper
Midwest and central Plains, it looks like we will be in a pattern
of multiple rounds of convection over the next few days with storm
complexes moving into Oklahoma from the north. It is still tricky
to determine specific geography too far in advance, but we do
appear to be in a wet pattern, especially by August standards.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 70 92 72 88 / 30 20 60 50
Hobart OK 71 96 74 94 / 20 20 40 30
Wichita Falls TX 71 97 76 98 / 10 10 20 20
Gage OK 67 92 68 85 / 40 30 70 30
Ponca City OK 69 88 70 85 / 70 30 70 40
Durant OK 70 92 75 93 / 10 10 20 40
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
25/25
Area Forecast Discussion...UPDATED
National Weather Service Shreveport LA
1005 PM CDT Wed Aug 9 2017
.DISCUSSION...
Vast majority of the convection has dissipated across our area
with the loss diurnal heating. The lone exception are a few light
showers moving northeast across portions of Northern Louisiana
south of a line from Many to Columbia. Most of the model guidance
keeps the coverage of precip tonight rather sparse and mainly over
Louisiana south of Interstate 20 and east of Interstate 49.
Therefore, updated the forecast and reduced rain chances areawide
through 12z Thursday morning.
A mention of patchy fog was also inserted into the 09z-15z time
frame Thursday morning across portions of East Texas west of a
line from Atlanta to Jacksonville. Surface dewpoint depressions
are already somewhat low in this area, which is also near the
remnant MCV/surface low. Forecast soundings and the HRRR
visibility progs suggest the potential for some patchy fog for a
few hours around sunrise.
Updated products have been sent.
CN
&&
.PREV DISCUSSION... /issued 643 PM CDT Wed Aug 9 2017/
AVIATION...
Sct aftn convection quickly dissipating prior to sunset. Thus,
should be quiet overnight with just a repeat of patchy areas of
fog and low cloudy either side of daybreak. Warm front will lift
well north into AR, but warm sector airmass across area appears
moist and unstable enough, with pws either side of 2 inches, to
warrant at least vcnty tstms across eastern portions of area, and
more marginal across western portions of area./07/
PREV DISCUSSION... /issued 400 PM CDT Wed Aug 9 2017/
DISCUSSION...
Scattered showers and thunderstorms have developed across the
region in response to an upper level low across Deep East Texas
and a retreating warm front just south of the Interstate 20
corridor. With PWATs over 2.00 inches, some locally heavy rain
will be possible under the stronger showers, especially in our
eastern zones. There could be some isolated hourly totals from
1-2 inches at some locations. Attm, believe rainfall amounts will
be low enough not the warrant a Flash Flood Watch.
The upper low will gradually push eastward from Deep East TX to
across southern LA overnight, while the retreating warm front will
wash out across the region. With the loss of daytime heating
and the exiting upper level low, the convection should decrease in
coverage overnight. However, with the upper low in the vicinity,
the models continue to keep some overnight convection across
portions of North Central Louisiana.
Beginning tomorrow, northwest flow aloft will begin to develop
across the region courtesy of upper level ridging in the Desert
southwest shifting eastward across central TX. This pattern will
hold across the region through next week. Embedded disturbances
within the flow aloft and daytime destabilization will keep
persistent precip chances through early next week. By mid-week
next week, a broad Upper low moving east-southeast across the
Great Lakes region will send down a backdoor cold front across the
region that could provide an additional focus for precip.
Temperatures will remain below normal through the period with
daytime temps in the upper 80s to lower 90s. Only exception may
be when the next fropa arrives next week as temps could lower to
the lower to middle 80s across the northern zones,nearest to the
frontal boundary. /20/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 74 91 76 91 / 30 40 20 50
MLU 74 91 74 91 / 30 50 20 60
DEQ 71 90 73 90 / 10 30 20 60
TXK 72 89 74 89 / 20 30 20 60
ELD 71 88 73 89 / 30 50 20 60
TYR 74 91 76 92 / 20 30 10 40
GGG 74 91 76 91 / 30 30 20 40
LFK 74 91 75 92 / 30 30 20 30
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
09/07
Area Forecast Discussion
National Weather Service Topeka KS
631 PM CDT Wed Aug 9 2017
...AVIATION UPDATE...
.SHORT TERM...(This evening through Thursday)
Issued at 350 PM CDT Wed Aug 9 2017
As of 20z, just as several days in the past, upper level ridging
continues to dominate the central and southern Rockies. Slow
moving cold front remains draped across northwestern NE. Weak
isentropic lift within the 300-310K layer continues to maintain
scattered showers across central and eastern KS. Pwat values
across the area remain in the 1.5 to 2.0 inches, resulting in a
brief heavy rainfall potential. Instability remains rather meager
with mesoanalysis suggesting upwards of 500 J/KG. Therefore, only
expect a few rumbles of thunder through the afternoon and evening
hours. Initial batch of showers and thunderstorms will push
eastward of the area during the evening hours. Thunderstorms have
began to develop along the aforementioned boundary in northwestern
NE in response to an embedded shortwave within the northwest
flow. Current short range models tend to steer the bulk of
thunderstorm activity towards the better instability axis across
central and western KS. That being said, I still expect scattered
showers and isolated thunderstorms to traverse the CWA overnight
as the subtle shortwave passes. Behind any shower activity,
forecast soundings suggest a drying column with clearing skies.
With Td depressions approaching 0 and nearly calm winds, I expect
patchy fog to develop overnight. Especially for areas along and
north of Interstate 70.
As we transition into Thursday, lingering showers will exit the
southeastern counties by mid morning. Additional development is
expected during the afternoon and evening hours. The
aforementioned surface boundary in NE will be positioned along the
KS/NE by 21Z Wednesday afternoon. Another subtle shortwave is
noted by most short and mid range models. I expect thunderstorms
to develop in response to sfc heating, convergence along the front
and additional lift from the wave. Great disparity exists amongst
guidance regarding instability. Forecast soundings from the GFS
near MYZ mix the BL to near H750, resulting in MLcape near 600
J/KG while the NAM mixes to H850 with ~2000 J/KG of MLcape. Have
hedged my bet towards the NAM solution, given agreement with Hi-
Res solutions. Effective shear is forecast to approach 30 to 40
knots. Given these 2 parameters, I expect organized convection to
develop with large hail and damaging winds. Warm cloud depths
approaching 15,000ft and pwats remains in the 1.5 to 2 inch range
could result in heavy rainfall.
.LONG TERM...(Thursday night through Wednesday)
Issued at 350 PM CDT Wed Aug 9 2017
The end of this week into the weekend will be characterized by
continued unsettled weather, with the pattern gradually
transitioning towards a drier setup by early to mid next week.
Temperatures look to remain seasonably cool through the period.
A surface boundary currently extending from eastern South Dakota
to western Kansas will bisect the CWA by the start of the period
Thursday evening. An approaching shortwave/H500 vort max embedded
in a broad central CONUS longwave trough will aid in thunderstorm
development across western Kansas and eastern Colorado Thursday
afternoon. Models have for days been in agreement with the
progression of this thunderstorm complex southeastward along the
(convectively enhanced) baroclinic zone, though the track
placement for this complex has varied. Recent runs of the
NAM/EC/GFS have taken the bulk of the precip south and west of the
CWA, though 305 K isentropic lift aloft and mid-level kinematic
forcing may tap mid-level monsoonal moisture being advected
eastward with the subtropical jet and spread precip northward into
the CWA.
With SBCAPE values ahead of the boundary in NE Kansas around
1000-2000 J/kg with little inhibition per domestic model bufr
soundings and roughly 30 kts of effective mid-level bulk shear,
there a chance for thunderstorm development along the boundary in
the early evening hours ahead of this main MCC. This possibility
is reflected in both the GFS and NAM, which both have a linear
precip band developing along the KS/NE border between 00-03Z,
decaying after 06Z as it encounters subsidence attendant to the
main convective complex to the south and its low-level moisture is
cut off. Have continued with chance POPs for most of the CWA
given the deeper moisture in place and uncertainty in the track of
the complex/initial line of storms. There is some chance of
stronger storms with the convection along the boundary, mostly in
the form of hail/wind given the lack of low-level wind shear.
Heavy rainfall will be a concern given the amble deep moisture and
weak steering flow.
This complex as a whole should shift southward Friday morning
with surface high pressure building south from the Northern
Plains. The aforementioned baroclinic zone will stall out over
central Oklahoma late Friday and then advance northward Saturday
morning. Upslope convection from the High Plains will once again
track ESE along this baroclinic zone Friday night, lifting
northeastward with the boundary and attendant isentropic upglide
ahead of this effective warm front on Saturday morning. The
boundary will oscillate over the area through Saturday and Sunday
before high pressure becomes more established over the Northern
Plains on Monday.
While confidence is high that the region will remain in an active
pattern through at least the weekend, confidence in the timing of
the precip (especially beyond Friday morning) remains low given
the lack of any prominent synoptic boundary and the likelihood of
convection from the previous day influencing the timing and
location of subsequent storms. Confidence in how soon the region
will break from this active weather pattern is also in some doubt
given how the planetary scale models have been delaying the
arrival of the West Coast meridional ridge--not surprising given
this amplified blocking pattern. However, one benefit of this
pattern will be the cooler weather (somewhat unusual for early to
mid August). H850 temps struggle to vary much between +15 and +18
C, which will translate into highs in the low 80s and lows in the
60s through the period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday)
Issued at 631 PM CDT Wed Aug 9 2017
Surface obs and latest visible satellite show a relative area of
stable air across north central KS from the early day clouds and
rain. So am not confident storms across south central NEB will
hold together in order to impact the terminals. The better chance
for precip may come from isentropic upglide this evening and
overnight. There are some mixed signals from the convective
allowing models and it appears the storms across central KS may be
slightly further south than the 22Z HRRR depicts. So confidence
in precip is marginal to include in the forecast for the terminals
at this time. If there were to be some elevated showers, it may
be between 01Z and 05Z so will keep an eye out for this. Models
keep some cloud cover across east central KS through the night
mitigating chances for fog. But if skies were to clear out, there
could be some IFR or even LIFR VSBY through the morning. Will also
monitor trends for fog as the evening progresses.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Baerg
LONG TERM...Skow
AVIATION...Wolters