Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/10/19
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
833 PM CDT Fri Aug 9 2019
.UPDATE...
Issued at 830 PM CDT Fri Aug 9 2019
Will continue to make updates as threat of severe weather and
heavy rain moves off to the east and south this evening. Next
issue is whether any convection will reform tnt within LLJ axis
over the eastern CWA. Have my doubts, but will hold onto flood
headlines for the time being given uncertainty and the fact that
HRRR is adamant about more convection. Temperatures are generally
okay.
&&
.SHORT TERM...(This Evening through Saturday Night)
Issued at 327 PM CDT Fri Aug 9 2019
Severe storms already occurring in central sd this afternoon along
a strong warm front. With good deep layer shear, deep instability,
good low level turning, and moisture, expect severe storms to
continue to trek across the region into the evening hours. A
tornado watch has been issued into this evening. Otherwise, the
models show a surface low pressure area moving across southern sd
with a strong llj impinging on the warm frontal boundary. With
this good lift along with deep moisture expect moderate to heavy
rainfall with these thunderstorms tonight with some flooding
likely to occur. Bufkit soundings also show heavy rainfall
ingredients into tonight. LLJ, high precipitable waters, and warm
cloud depths point to heavy rainfall possibilities mainly across
the east. 1 to 3 inches of rain are expected across much of the
region with locally higher amounts. Thus, issued a flood watch
earlier for the region through much of tonight/early Saturday.
Otherwise, the storms will leave the eastern part of the region
Saturday morning with skies becoming mostly sunny. Highs will range
from the mid 70s east to the mid 80s west by late afternoon. We may
have a return to some storms later Saturday night out west.
.LONG TERM...(Sunday through Friday)
Issued at 327 PM CDT Fri Aug 9 2019
An upper level ridge will begin the long term on Sunday with mostly
dry conditions expected. The in-house pop blend is a bit
overzealous, especially compared to the ECMWF, NAM, and Canadian
model. Precipitation chances will increase substantially Sunday
night into Monday as upper level trough and surface low pressure
system crosses the region. As of now, the best instability and LLJ
is focused south of this CWA, or closer to the Nebraska border. This
system should push east of the region before 18Z Monday with dry
conditions possible through Tuesday.
A lee of the Black Hills surface low pressure system may develop on
Wednesday with WAA and an increasing LLJ Wednesday night bringing
the potential for showers and thunderstorms, mainly in the eastern
CWA. Increasing upper level heights, along with southerly flow in
the lower levels will bring humid conditions into the region by
Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 615 PM CDT Fri Aug 9 2019
Showers and storms will continue to move east across the region
overnight, but the threat of severe weather is waning. Areas of
lower cigs are expected to develop across much of the region
overnight, along with areas of fog. The fog and low clouds will
likely linger through Saturday morning.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Flood Watch through Saturday morning for SDZ020>023.
MN...None.
&&
$$
UPDATE...TDK
SHORT TERM...Mohr
LONG TERM...SD
AVIATION...TDK
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
835 PM EDT Fri Aug 9 2019
.SYNOPSIS...
A weakening cold front will move across the local area late
tonight, then stall near the North Carolina coast over the
weekend.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 130 PM EDT Friday...
Latest analysis shows a weak pre-frontal sfc trough in place
along the coast from the carolinas into southern New England. A
secondary trough was also in place across the piedmont evident
by a slight shift ion winds from DC southwest to Farmville and
Raleigh. Sct CU and some showers and storms were starting to
develop as of 230 pm. Deep layered WNW flow was persisting
above 850 mb and this limiting deep moisture and resulting in
some inhibition, but not enough to keep activity at bay. The
HRRR and ARW remain in good enough agreement that scattered
showers and storms will develop and expand some in coverage
between 3 pm and 4 pm then move southeast in the NW flow.
Question is how widespread will convection be and the trend in
the HRRR since 12z has been to slightly decrease storm coverage
across eastern and southeast VA. Still maintains 30-50 POPs, but
do not intent to go likely at this point. MLCAPE should reach
1500+ j/kg this afternoon mainly near the Bay and across
southeast VA and northeast NC. Scattered storms which are able
to develop should be able to produce gusty winds and frequent
lightning.
The weakening cold front will settle just south of the forecast
overnight, across NC. Evening convection will decrease from
north of south though some lingering showers and storms may
continue near the NC/VA border south even late tonight as the
front potentially slows. In general drier air will arrive after
midnight (w/ dew points falling to the u50s- l60s across the
NW). Lows 60-65F N and NW to around 70F far SE.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
As of 130 PM EDT Friday...
Still shaping up to be a really nice weekend over much of the
area. Some of the model guidance does leave the lingering sfc
trough near the Albemarle and Pamlico Sounds Sat- Sun which may
mean a bit more in the way of clouds along w/ the potential for
ISOLD showers along the Albemarle Sound counties and Outer
Banks. Otherwise, not quite as warm w/dew points down at more
comfortable levels. Mostly sunny N and central areas both
days...partly sunny S and SE. Highs in the m-u80s both days...a
bit cooler at the beaches. Clear- partly cloudy Sat night w/
lows in the l-m60s...except near 70F at the immediate coast in
SE VA/NE NC.
Continued dry but warmer on Monday. Sfc high will settle
offshore, shunting weak boundary back north as a warm front.
Slightly warmer with highs in the upper 80s to around 90.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 130 PM EDT Friday...
The extended forecast period will start out with a warming trend
getting rather hot and dry partially due to the zonal flow
aloft and upper ridge which builds in Monday and persists into
TUE. Humidity increases through next week as an front looks to
approach from the NW late Tue into Tue night. An upper wave
also drops SE late Tue supporting late day and evening scattered
showers and storms. Ahead of the showers and storms highs hit
lower 90s on Monday at then middle 90s on Tuesday which should
be the hottest day next week.
The upper trough hangs up and deepens on Wednesday making for
continued unsettled weather with showers and storms. The front
also hangs up in the southeast. Expect Wed to see more showers
and storms with highs in the upper 80s to lower 90s. A wave
develops along the front just off the coast Thu into Fri with
high pressures to the NW. This could make for a tricky forecast
for the end of the work week, but as of now things look
generally drier and cooler for late week.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 830 PM EDT Friday...
The surface cold front continues to make slow progress
southeastward through NERN MD and NW VA this evening with some
scattered convection continuing in SE VA and NE NC. THis front
will continue to push SEWD overnight pushing into central NC by
Sat morning. Behind the front much drier is pushing southward
with sfc dewpoints in the 50s. THis should allow the clouds to
clear in most areas and vfr conditions to continue at all TAF
sites. Will need to monitor ECG for some possible fog
development late as the low levels did see an increase in
moisture with an evening storm. But mixing might be enough to
keep the fog away. For now have been optimistic with the
forecast and kept vfr conditions in place.
Canadian High pressure will build into the area by Saturday
morning with vfr conditions expected for the entire day. an
isolated shower is still possible for NE NC on Saturday
afternoon depending on how far south the front goes, but for now
have just allow for a developing afternoon cu field with some
mid level moisture along and north of the front.
OUTLOOK...VFR conditions are expected Sat night into early next
week. A cold front is expected Tues into Wed and could produce
some MVFR conditions with showers.
&&
.MARINE...
As of 400 PM EDT Friday...
No headlines in the short term tonight thru Sun. Winds were
variable 10 kt or less acrs the waters late this aftn. Waves
were 1-2 ft and seas were 2-3 ft.
A cold front will approach the waters from the NW this evening,
then drops acrs the waters overnight. With fairly robust NW
flow aloft, there is the potential for a few strong/severe
storms to precede the cold front late this aftn and evening.
These storms will bring the chance for winds in excess of 35 kt
and locally enhanced waves/seas. The front will become nearly
stationary over NC during Sat, then gets pushed farther south
Sat night and Sun, as sfc high pressure builds acrs nrn portions
of the region and offshore. Mainly SSW winds around 10 kt or
less this evening, will become NW then N tonight into Sat
morning. The flow becomes less than 10 kt and variable Sat aftn
into Sat night, before winds turn NNE again by Sun morning.
Onshore winds expected Sun aftn into Sun night, as the high
shifts farther offshore. South and southwest winds will
increase late Mon into Tue in advance of another cold front.
Seas build to 2-3 ft S and 3-4 ft N, with waves 1-2 ft.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.
&&
$$
SYNOPSIS...MAM/JAO
NEAR TERM...MAM/JAO
SHORT TERM...MAM/JAO
LONG TERM...JAO
AVIATION...ESS/JAO
MARINE...TMG/RHR
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1055 PM CDT Fri Aug 9 2019
.UPDATE...
Issued at 948 PM CDT Fri Aug 9 2019
Convection has generally shifted south of the state line in
Nebraska with only a few cells left in south central South Dakota.
Lighter rain continues along and south of Hwy 30/34 east of
the James River to about OTG and Slayton. The convection has
shifted the boundary to the south of the area. CAMs continue to
show convection along and north of I90 later tonight as LLJ
increases. However, CAMs have struggled with convective evolution
all evening - generally being too far north and too slow. So, at
this time, expecting that as LLJ increases in the next hour or
two, new convection will favor south of I-90 into Nebraska. The
only exception would be in there can be a 2-4 hour break until
06-08Z for new convective initiation then the front may be able
to shift back north and favor new development into east central
SD. At this time, favoring a southern solution with PoPs highest
in the Missouri Valley through 06Z. and lowering to 30-60%
along/north of I-90 with the highest PoPs in southwestern MN. Have
also decreased QPF after 06Z given lower confidence in overall
rainfall across the area. As a result we have cancelled the Flood
Watch along and north of I-90 but continued it south of I-90 where
the threat for heavy rain continues for at least the next 2 to 4
hours. The severe threat has decreased markedly with lack of a
significant lifting mechanism. The RAP is likely overdoing MLCAPE
given the front is farther north in the model than observed but
still expect CAPE around 1000 J/kg over much of the area with
1500 J/kg near the stateline so could see an marginal severe hail
if a stronger updraft is able to develop.
&&
.SHORT TERM...(This Evening through Tonight)
Issued at 227 PM CDT Fri Aug 9 2019
A very potent severe weather setup continues to build this afternoon
across central and western South Dakota. Mid-afternoon surface and
satellite analysis showing well defined surface boundary just south
of the Missouri River and Pierre southeast towards Chamberlain and
approaching Charles Mix county. Isolated surface based convection
has already started to develop in the warm sector, along with
enhancement of elevated convection across northern South Dakota.
This afternoon and evening: Very moist boundary layer air has
advected northward south of this frontal boundary, with dew points
in the lower 70s. This has allowed for the development of a a
large MLCAPE reservoir approaching 2500 J/KG into the western
third of the CWA. Isolated surface based convection to our west
and northwest should become more numerous through the afternoon
as large scale accent arrives from shortwave energy over NE
Wyoming later this afternoon. Increasing winds aloft have already
pushed effective shear values into the 40 to 50 knot range this
afternoon, and this will continue to rise as low-level flow
increases this evening.
This setup will favor the development of one or more discrete
supercells across central South Dakota into the early evening,
with eventual cell mergers developing into bowing segments and
clusters as storms turn southeast along the edge of the
instability gradient and dive towards and across the James River
Valley.
As far as risks are concerned, soundings show slightly modest mid-
level lapse rates and are absent of thick hail growth CAPE profiles,
however strong shear should support lofting of hail with potential
for 2.5" hail in supercells. Greatest risks this afternoon and
evening will arrive from damaging winds and tornadic risks. Eventual
advection of dry air in the mid-lvls of the atmosphere will result
in DCAPE values approaching 1500 J/KG in the western half of the
CWA. This will support wind gusts up to 80 mph in HP supercells
along with bowing segments later this evening. More concerning
are the significant tornadic parameters showing up this afternoon
and early evening along the Missouri River Valley and west of the
James River valley. Effective 0-3 SRH values are already
approaching 300 M2/S2 near initial development this afternoon near
Kadoka, with increasing low-level flow pushing those values
towards 500 M2/S2 by early evening towards Chamberlain and Lake
Andes. 0-1km shear/SRH values are also very impressive along the
frontal boundary, sitting around 150-200 M2/S2 and 20 knots
respectively by early evening. LCL heights also fall in the
favorable category, lowering down towards 600-750 M AGL later
this afternoon. Should discrete cells become anchored to the
surface boundary, an extended long track tornado threat could be
possible into the James River Valley. However, even smaller bowing
segments could be strong enough to produce tornadoes given the
environment this evening.
Further east, while instability wanes towards the I-29 corridor,
it`s possible to have residual MCS complex slide eastward late this
evening bringing a strong wind risk. It appears however that the
greatest severe weather risk falls along and west of a line from
Huron to just east of Mitchell towards Yankton.
Heavy rain will also be a large risk this evening and overnight.
Slow propagating supercells and any eventual complex will
certainly have the potential for flash flooding. Additionally, as
the LLJ refocused over MN and far eastern SD after midnight, a
secondary area of heavy rain may develop along the Buffalo Ridge.
Have issued a flood watch to cover both the large scale and flash
flood potential into Saturday morning.
.LONG TERM...(Saturday through Friday)
Issued at 227 PM CDT Fri Aug 9 2019
Saturday-Sunday: Anticipating rain to linger over the eastern CWA
behind this wave well into the morning hours. Residual cloud cover
should limit temperatures and have lowered accordingly. Temperatures
further south may rebound slightly towards 80 in the afternoon as
surface low pressure slides east. A very pleasant day is expected
on Sunday as temperatures climb back towards normal and dry
conditions continue.
Monday-Tuesday: A series of mid-lvl shortwaves arrive late Sunday
night with one or more MCS developing off the western Plains and
sliding eastward. We won`t really scour out much of the moisture in
the atmosphere this weekend, so the antecedent conditions ahead of
these waves will be favorable for heavy rainfall. The locations and
track of the rain are still slightly in doubt however. While the
greatest severe weather risks with these MCS appear to stay south,
we`ll certainly need to monitor. Dry air moves in for Tuesday, along
with slightly cooler temperatures.
Wednesday-Thursday: The middle of the week again favors dry
conditions, with gradual warming by Thursday and Friday of next
week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1052 PM CDT Fri Aug 9 2019
MVFR and potentially IFR stratus will attempt to develop on the
back edge of the MCS. If stratus develops, could see additional
storms develop in uncapped environment. Will be hard to shake the
stratus on Saturday, though moisture will gradually thin through
the day, possibly leading to breaks in the clouds late day.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Flood Watch until 7 AM CDT Saturday for SDZ063>070.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...Schumacher
SHORT TERM...Dux
LONG TERM...Dux
AVIATION...BT
Area Forecast Discussion
National Weather Service Hastings NE
643 PM CDT Fri Aug 9 2019
.SHORT TERM...(This evening through Saturday)
Issued at 425 PM CDT Fri Aug 9 2019
Afternoon upper level pattern consists of a strong dome of high
pressure over the southern Plains, with troughs on either side
over the eastern CONUS and just offshore the West Coast. A
shortwave can be seen over central SD and this will ride SE in the
NW flow tonight. A sfc low associated with this trough is located
over SW SD, with a lee trough extending southward through the
central High Plains. A cold front is noted W of the sfc low over
extreme W SD into WY. Locally, current temperatures are in the
80s with dew points in the 60s, pretty seasonable for this time of
year.
Will continue to see warm and dry conditions through the evening
hours as any focus for tstms remains well away from the area.
However, after midnight, we may get clipped by the far S end of
the SD wave as it crests the top of the ridge and turns SE. The
HRRR has been consistent in showing a band of weak convection very
close to our far N/NW CWA, so have inserted a slgt chc POP for the
06Z to 11Z time frame.
Can`t rule out some patchy fog overnight, but held off on
including attm given stronger S winds compared to past few nights.
On the other hand, could envision some low stratus once again
tonight.
Saturday should be dry for most of the daytime hrs. The
aforementioned cold front will dive S and likely stall somewhere
over the CWA. This could be the spark for a few tstms as early as
late afternoon. CAPE and shear is there for severe convection,
however the larger scale pattern will feature large scale ridging
and weak height rises. So, while the potential for an isolated
strong to severe storm exists as early as late afternoon, it is a
conditional potential.
Expect warm temps ahead of the front across our southern zones.
Have increased highs a couple of degrees into the mid 90s. Tds
around 70 will yield heat indices in the low 100s for several hrs
in the aftn, not far from heat advisory criteria.
.LONG TERM...(Saturday night through Friday)
Issued at 425 PM CDT Fri Aug 9 2019
The main concern will be multiple rounds of convection and
potential for svr tstms and hvy rn.
By Sat eve, the upper ridge axis will shift E far enough to turn
upper flow to the SW. Several models indicate a weak wave ejecting
NE during the eve which should lead to scattered to widespread
convection developing over the High Plains during the late
aftn and eve. This activity should spread E toward the W CWA
during the eve and continue E/ESE overnight, generally along the
aforementioned cold front. The NAM develops 40-45kt LLJ over
central KS by 06Z Sun, with the nose intersecting this boundary.
Aloft, there appears to be decent divergence from the RER of a jet
streak over Dakotas/MN. Thus, ingredients appears to be coming
together for one or two MCSs Sat night into early Sun, with some
severe potential. Heavy rn may be the main threat, though, given
PWATs near 2" and good moisture conv along front/nose of LLJ. Held
off on a Flash Flood Watch for now for a few reasons: 1) likely
still 24+ hrs out before any hvy rain threat, so still plenty of
time to get better handle on the potential. 2) models often
struggle with placement this far out in this type of pattern and
just generally during this time of year. Currently, S zones are
most favorable for this activity. 3) S/SW portions of the CWA are
quite dry over the past 30 days, so most areas can take a good
amount of rain. Overall, I think there will be at least pockets of
heavy rn, but confidence on coverage and placement remains low at
this time.
There`s a pretty decent chance for another round of storms Sun eve
into overnight, some of which could once again be strong to svr
and produce hvy rn. This wave appears stronger than Sat night`s
wave. Biggest thing to watch with this round will be to see if it
tracks over or close to any areas that receive hvy rain Sat
night as that could incr the flash flood threat. At this time,
chcs appear higher across NE zones which is a little further N
than Sat night. This would, obviously, be idea and spread the rain
out over a large portion of the area. Most areas W of a line from
Shelton to Superior could use some rain. Highs Sun range from mid
80s to low 90s, N-S.
Otherwise, expect some additional off and on low chances for pcpn
Mon-Thu as the upper pattern deamplifies and the main flow sets up
just N of the area. This usually results in getting clipped by
several low amplitude perturbations of which carry low
predictability this far out. As such, expect mainly near to
slightly below normal temperatures for much of next week.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 643 PM CDT Fri Aug 9 2019
VFR conditions expected to prevail. Have removed the chance for
fog/low stratus in the TAFs this period. Southerly winds look to
be strong enough to help keep low levels mixing more and preclude
fog development. Something to watch though. South to southwesterly
winds expected tomorrow.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Thies
LONG TERM...Thies
AVIATION...Billings Wright
Area Forecast Discussion
National Weather Service Goodland KS
554 PM MDT Fri Aug 9 2019
.SHORT TERM...(This evening through Saturday)
Issued at 125 PM MDT Fri Aug 9 2019
Cloud cover slowly burned off across much of the region through the
morning hours, with a layer of cumulus/stratocumulus developing then
dissipating into the afternoon. 500 mb RAP analysis and satellite
show and area of high pressure located over Texas with ridging
extending north into the Plains and Rockies. Southerly winds were
observed throughout the region today at 10 to 15 mph. At 1 PM MDT,
temperatures were in the 80s.
The tri-state area looks to be on the northern edge of the upper
ridge tonight as it begins to gradually shift eastward. A shortwave
is anticipated to work its way through the flow from New Mexico to
Colorado and towards Kansas through the evening hours. This
disturbance should cause storms to initiate along the Rockies which
will progress east/northeast into the region. How far these storms
make it into the area before dissipating is in question. At this
time, the better chances for showers and thunderstorms remain along
and west of the Colorado border. Sufficient shear and instability
indicate a few strong to severe thunderstorms cannot be ruled out,
with hail up to quarter size, damaging winds, and locally heavy
rainfall as the main threats. Most thunderstorm activity should end
by midnight. Temperatures fall into the 60s to low 70s as cloud
cover decreases.
Dry conditions are forecast Saturday morning. However, another
shortwave is expected to rotate through the ridge and generate
another round of showers and thunderstorms from the afternoon
through the overnight hours. This precipitation should be more
widespread in comparison to today. Saturday`s high temperatures will
be in the upper 80s to mid 90s.
.LONG TERM...(Saturday night through Friday)
Issued at 206 PM MDT Fri Aug 9 2019
Forecast concern be active and wet pattern with some chances for
severe but increasingly better chances of heavy rain and flash
flooding. Satellite is showing an amplified pattern from the Pacific
into eastern North America. Flow highly amplified and even blocky in
the central Pacific. Ridge over the country is centered over Texas
which is allowing a strong connection to subtropical/monsoonal
moisture.
Saturday night...Weak shortwave trough will move through the area in
weak, mainly southwest flow aloft. In general the models show a
boundary over or just south of the area during the period. However,
they differ on where to put that boundary. Air mass is moist and
unstable with Precipitable water values 1.5 to 2 inches which near
to above record levels.
As has been the case in this very moist and weak flow/forcing
environment, models, especially the high resolution guidance, having
a difficult time in deciding where to put the rainfall. Considering
the above reasoning believe there will be some heavy rainfall but
problematic on where to put it. So raised the chance of
precipitation a little. Since we have been dry for a few days and
due to the disagreement in the model solutions, decided not to put
out a Flash Flood Watch. Upcoming shifts will need to look at this
again.
Sunday/Sunday night...Upper jet remains to the north of the area.
Same general pattern is in place at the beginning of the period,
ridge centered over Texas with troughing over the Pacific northwest.
However this transitions to a nearly zonal flow by the end of the
period. This is due to a couple rather strong shortwave troughs
moving through and shoving the ridge further east and bringing
better chances of rainfall to the area unless the previous nights
convection and associated mesoscale affects mess that up.
Forecast blend pops a good chance of precipitation. That looks
reasonable and left alone. Depending on how the rainfall goes
Saturday night, a Flash Flood Watch may be needed since antecedent
conditions will be more favorable and high PWs still remain.
Monday/Monday night...It looks like the main shortwave that moved
into the area the period before will move through during the daytime
hours. So there could be some linger precipitation during the
morning and maybe some redevelopment in the afternoon. However,
there looks to be no definable shortwave coming during the night.
Through the day the jet remains north of the area but gets closer.
Weak right rear quadrant moves through the area during the night.
Latest forecast blend has the daytime dry with a slight chance to
low chance in there during the night. That looks reasonable given
the reasoning above.
Front is brought through the region and by the end of the period
will be south and west of our area leaving the area in a post
frontal upslope environment. PWs remain near 1.5 inches. So again
locally heavy rainfall will be possible.
Tuesday through Friday...Ridging aloft looks like it try to build
into the area during the beginning of this period but the strongest
portion of the ridge remains well south. During the end of this
period the ridge tends to elongate but still remains well south of
the area. So general setup/pattern will allow shortwave troughs to
move through in the west to southwest flow aloft. This far out those
of course will be hard to time out. Main jet looks well north.
However, weak jet/axis looks to be over/near the area during this
time.
Front mentioned above remains to the south and west but moves east
from the Front Range a little. During the last two days that front
moves across the area as a warm front with a new lee trough settling
over the western portion of the area by the end of the period.
Precipitable water values gradually lower during the period. They
will start out at 1 to 1.5 inches and drop down to 0.75 to 1 inch by
the end.
Latest forecast blend has the wettest conditions Tuesday and Tuesday
night with dry to slight chance pops in the last three periods.
Again this looks reasonable and did not change. Also the
temperatures look reasonable per reasoning above. This means after a
slightly cooler day on Tuesday there will then be a gradual warming
trend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 550 PM MDT Fri Aug 9 2019
VFR conditions are expected through the 00Z TAF period at MCK and
GLD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JBH
LONG TERM...BULLER
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1045 PM EDT Fri Aug 9 2019
.UPDATE...
Issued at 1045 PM EDT FRI AUG 9 2019
The boundary continues to help fire off and sustain convection
this late evening hour. Much of this is rain showers now, but we
have seen the occasional cloud to cloud and cloud to ground
lightning strike detected by ENTLN. Given this will keep the
mention of thunder in the grids and HWO. The trend will be
downward with these storms, as inversion sets up and instability
wanes. Updates have been sent.
UPDATE Issued at 754 PM EDT FRI AUG 9 2019
The latest surface analysis suggests a frontal boundary is draped
from west to east across the heart of eastern Kentucky. This is
leading to showers and storms developing along and near this
feature. While some stronger storms did develop underneath ample
shear and CAPE profiles, there seemed to be some kind of CAP aloft
leading lack of better development upward. The shear was
certainly there as storms that developed across Clark and Powell
sent cirrus blow off toward the Virginia border based on GOES-16
data. The CAMs did well portraying the general convection, but did
lean toward the HRRR for PoPs. Given this there will be an
overall downward trend in the convection this evening and only
concern will be fog production through the night. Adjusted PoPs
accordingly, but otherwise more minor update overall.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 442 PM EDT FRI AUG 9 2019
A cold front continues to sag south across the area and is
currently located across the northern portion of the CWA.
Convection in WV has been more vigorous where the alignment of
instability and shear has been best so far. MLCAPE should still in
the 1000 to 1500 J/kg range over the next few hours with
effective bulk shear in excess of 30kt. Lighting has been recently
detected in a couple of cells near and just south of the I 64
corridor. Forcing should remain limited as we head into the
evening with the cold front sagging south, though given the
instability and shear isolated to scattered convection is
anticipated in the vicinity of the boundary. A strong storm or two
with gusty winds or small hail cannot be ruled out.
The boundary should sag south of the area after midnight with
showers and storms possible through that point. Once the front
sags south of the area and as skies clear and high pressure begins
to build in drier air will arrive more quickly in the north.
However, dewpoints will be slower to fall further south and fog
development appears most likely in valleys south of the Mtn
Parkway. High pressure will settle into the OH Valley on Saturday
and reach the upper OH Valley late in the period. At the same
time, the upper level flow will remain out of the northwest
ushering in drier air with gradual height rises through Saturday
night.
As for temperatures, lows will be a bit colder than this morning
with lower 60s in the north and mid to upper 60s in the south.
High on Saturday should be well into the 80s and the higher Max T
from the NBM and blended guidance was favored as it has been
verifying better than MOS recently. Also much of the area has been
drier lately thus leading to drier soils and allowing for a bit
more heating. The bulk of the region should fall into the lower
60s on Saturday night with a 58 or 59 possible in some of the
normally colder northeast valley locations.
.LONG TERM...(Sunday through Friday)
Issued at 448 PM EDT FRI AUG 9 2019
A strong upper level ridge will slowly begin expanding eastward from
the south-central Conus, with increasing heights expected over
Kentucky. A strong surface high will also be moving across the
Ohio Valley, with abundant sunshine and light winds expected.
Temperatures will top out in the mid and upper 80s, but dew points
should keep RH values at bay, with Heat Indexes very similar to
the temperatures.
Things will begin heating up from here. By Monday, the area of high
pressure will begin shifting just northeast of the state, with upper
level ridging continuing to gain hold. Srly flow in the low levels,
though light, will be enough to increase the moisture flow into the
region, and with upper level ridging still holding strong,
temperatures will rise to the 90 degree range or just above.
Humidity increase will cause a spike in heat indexes, making it feel
like the mid 90s, and even upper 90s in the southern CWA. Also can`t
rule out a bit of afternoon convection, though the GFS, NAM, and
newest ECMWF don`t see as on board with this as the NBM. Even still,
pops will generally be under 20 percent, and fall off in the evening.
Moisture will continue to increase into Monday night as an area of
low pressure moves into the Lower Great Lakes and drags a cold front
southeastward towards the Ohio River. Southerly flow will continue
to increase, with enough moisture and instability entering the
region to induce showers and thunderstorms by Mon night, continuing
to increase through the day Tuesday as the front passes over and we
reach peak afternoon heating/instability. Our highest temperatures
of the forecast are expected this day, along with our highest heat
indexes. Highs will be in the low 90s, but it will feel like its
around 100 degrees. This will be a day to watch as we get closer,
both for heat concerns, as well as for high PWATS and convection.
The front will pass through late Tuesday night, cutting off precip
chances during the first half of the day Wednesday from NW to SE.
However, there won`t be much reprieve from the hot and humid
temperatures. High will still be in the mid and upper 80s, but it
will feel more like the low 90s in many locations. Upper level
heights will be on the rise again for Thursday, with mostly clear
conditions and similar temperatures as Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 730 PM EDT FRI AUG 9 2019
We are looking at VFR to the begin the TAF period, but some
showers and thunderstorms have developed along a cold front this
afternoon. This could lead to quick reductions in CIGs and VIS,
but this should be short lived if a site experiences one. We are
looking at fog development later tonight around 7Z to 8Z or after
for most locations. The dryer air will mitigate fog at SYM, but
airport mins are not out of the question elsewhere. We will see
this fog lift and/or dissipate through the morning at around 14Z.
This will lead to VFR skies for Saturday, with some flat cumulus
not out of the question in the afternoon. The winds will remain
light through the TAF period, with winds coming out of the north
as boundary moves across.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...JP
LONG TERM...JMW
AVIATION...DJ
Area Forecast Discussion
National Weather Service North Platte NE
656 PM CDT Fri Aug 9 2019
.SHORT TERM...(This evening through Saturday night)
Issued at 322 PM CDT Fri Aug 9 2019
The thunderstorm forecast late this afternoon and tonight follows a
blend of the HRRR, HREF, RAP, NAMdng and the model blend which
places isolated to scattered thunderstorm activity from roughly
Deuel county northeast to Valentine. The srn storm activity is
expected to weaken early this evening which the nrn storm activity
may last for several hours as it advances east through nrn Nebraska.
POPs for tonight are capped at 30 percent to account for
uncertainties in coverage. Some models like the HRRR produce very
little storm activity tonight.
A significant and potentially major league heavy rain event could
develop across parts of western Nebraska late Saturday afternoon
through Saturday night. Precipitable water increases to over 1.70
inches with a deep warm layer supporting tropical type rain
processes. The problem with the forecast is locating the low level
focus for best rain chances. The models may be placing the h850mb
front somewhere across KS with swrn Nebraska in an easterly upslope
flow. A frontal location near the NE-KS border would favor swrn
Nebraska for heavy rainfall. The location of the front will become
known later tonight in the wake of the storm activity across the
Dakotas.
POPs for this portion of the forecast capped at 50 percent and the
forecast uses the same model blend as the tonight period. Once
again, some models such as the GFS and ECM produce very little
rainfall across wrn Nebraska Saturday while the NAM12 places heavy
rain centers of 4 to 6 inches over nern Colorado and nwrn Kansas/far
swrn Nebraska. The flood guidance across swrn Nebraska is less than
2 inches in an hour which could easily be eclipsed given the
moisture available.
.LONG TERM...(Sunday through Friday)
Issued at 322 PM CDT Fri Aug 9 2019
The atmosphere transitions from quasi-barotropic to baroclinic
Sunday as a nrn stream disturbance infiltrates the tropical moisture
plume across the cntl Plains. The GEF output places a broad heavy
rain center over wrn and ncntl Nebraska and if this verifies, back-
to-back heavy rain events will occur. Parts of ncntl Nebraska might
be post-frontal with sfc low pressure over swrn KS and nern WY as
high pressure builds in to the upper Midwest. The double-barrel sfc
low pressure across WY and CO/KS will produce moist upslope east and
southeast winds across wrn Nebraska. The NAM and GFS continue
precipitable water above 1.70 inches Sunday night. The GFS and ECM
favor Sunday for the better rain chance while the NAM and SREF favor
Saturday.
A cold front will begin to dry out Wrn and ncntl Nebraska Monday
with northwest winds developing. Lingering moisture will continue
shower and thunderstorm chances Tuesday and beyond but POPs are 30
percent or lower.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 655 PM CDT Fri Aug 9 2019
The main aviation concern will the chance for rain and thunderstorms
across portions of north central Nebraska. At this time, the best
chance for development will remain across the north, impacting only
KVTN. Frequent lightning, erratic winds, small hail, and heavy rain
could all be threats with these thunderstorms. Otherwise, VFR
conditions will remain across the region through Saturday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Kulik
Area Forecast Discussion
National Weather Service Louisville KY
749 PM EDT Fri Aug 9 2019
...Updated Aviation Discussion...
.Forecast Update...
Issued at 646 PM EDT Fri Aug 9 2019
Diurnally-driven convection has consolidated into a narrow band
right along the front (running through Elizabethtown and Richmond
areas), and this activity is slowing dropping southeast. The cu
field has diminished considerably north and south of the boundary,
so have updated PoPs to reflect the latest trends. Due to the weak,
consolidated nature of the convection, think it will die pretty
quickly after sunset.
&&
.Short Term...(This evening through Saturday)
Updated at 333 PM EDT Fri Aug 9 2019
Diurnal cumulus field is in full swing across the region this
afternoon. As expected, temperatures have warmed into the upper 80s
with a few spots in the lower 90s. The cumulus field is a bit more
agitated right along the I-64 corridor. This appears to be where a
weak front is located. The HRRR still suggests that some isolated-
scattered convection may fire along and just south of I-64 over the
next few hours. Overall HRRR coverage is slightly less than in
previous runs. For now, plan on keeping some 20-30% PoPs south of I-
64 for the next several hours.
Surface front is forecast to push southward overnight and we`ll see
a switch in the wind flow to the north and northeast overnight. Some
patchy fog will be possible mainly across southern KY. Lows will be
in the mid-upper 60s with some lower 70s along the KY/TN border
region.
For Saturday, mainly dry weather is expected across the region.
Highs look to warm again into the mid-upper 80s in most locations
with a few spots topping 90 again.
.Long Term...(Saturday night through Friday)
Updated at 250 PM EDT Fri Aug 9 2019
Saturday Night - Tuesday...
Dry weather is expected Sat night through Monday morning as sfc high
pressure largely controls the region. The next chance of rain looks
to arrive on Tuesday as a cold front moves through the region from
NW to SE. While organized severe weather doesn`t look likely at this
time, some strong storms may be possible.
We`ll see a warming trend in temperatures as an upper level ridge
works into the Ohio Valley early next week. Temps in the upper 80s
to lower 90s on Sun will climb into the lower 90s almost area wide
for Mon/Tue. Moisture pooling ahead of front will cause dewpts to
rise through the 70s Mon/Tue. 70s dewpts combined with highs in the
lower 90s will result in heat index values of 100-105 for Mon/Tue
with Tuesday being slightly warmer potentially. Afternoon storms on
Tues will provide relief to some areas.
Wednesday - Friday...
Lingering showers/storms should exit the area Wed morning with the
cold front leaving the rest of the week dry. Slightly cooler temps
and lower humidity levels can be expected Wed-Fri with sfc high
pressure and lower thicknesses in place.
&&
.Aviation...(00Z TAF Issuance)
Updated at 749 PM EDT Fri Aug 9 2019
SCT-BKN cu field is now oriented in a fairly narrow band along a
cold front stretched west to east across central Kentucky this
evening. In addition, we do have some mid-level clouds around 10-12
kft streaming across southern KY. The TAF sites are likely to remain
VFR and dry through the remainder of the evening. Scattered
convection has drifted south of HNB/SDF/BWG. The lingering showers
along the front are likely to diminish after sunset before they have
a chance to impact BWG.
Skies at the northern TAF sites will remain mainly clear overnight
as drier air advects via a north wind. Forecast is tricky for BWG
south of the front. Mid-level clouds may be BKN at times between 00-
12z, but should scatter out enough to allow some fog potential after
08z. In general, patchy dense fog will be possible across southern
KY early Saturday with plenty of low level moisture and nearly calm
winds in place near and south of the boundary.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...EBW
Short Term...MJ
Long Term....AMS
Aviation...EBW
Area Forecast Discussion
National Weather Service Tulsa OK
906 PM CDT Fri Aug 9 2019
.DISCUSSION...
Earlier convection has dissipated, although modest increase
in low-level jet/speed convergence should result scattered
convection across parts of eastern OK/northwest AR mainly
after midnight. Based on recent HRRR output and 00Z NAM,
have increased PoPs a bit across western AR as well as
shifting the QPF axis just a bit farther south.
Leftover morning convection/debris clouds will impact
potential heating on Saturday, so will leave the current
Heat Advisory as is.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 75 94 77 98 / 30 10 0 0
FSM 75 93 77 99 / 40 20 0 0
MLC 76 96 78 98 / 20 10 0 0
BVO 74 92 75 95 / 30 20 0 10
FYV 72 88 74 93 / 40 40 0 10
BYV 71 88 74 95 / 30 40 10 20
MKO 75 94 75 97 / 30 10 0 0
MIO 73 91 74 95 / 30 30 10 10
F10 74 96 76 99 / 20 10 0 0
HHW 77 97 77 98 / 10 10 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Heat Advisory from 1 PM to 8 PM CDT Saturday for OKZ049-053-060-
064>067-070>076.
Heat Advisory from 1 PM to 8 PM CDT Sunday for OKZ049-053-060-
064>067-070>076.
AR...Heat Advisory from 1 PM to 8 PM CDT Saturday for ARZ019-029.
Heat Advisory from 1 PM to 8 PM CDT Sunday for ARZ019-029.
&&
$$
SHORT TERM...18
Area Forecast Discussion
National Weather Service Tucson AZ
823 PM MST Fri Aug 9 2019
.SYNOPSIS...Abundant moisture will remain in place through the
weekend with a weather system moving north across the area Saturday.
This combination will bring occasional thunderstorms to the area with
an elevated risk of flash Flooding anytime from late tonight through
Sunday night. Scattered thunderstorms are again expected Sunday
mainly east of Tucson. Drier and hotter weather is forecast for much
of next week.
&&
.UPDATE...Made an update to the forecast to lower rain chances
for tonight based on the recent trends and the latest model
solutions. The onset of widespread rainfall will be delayed several
hours as suggested by the HRRR and recent National Blend of
Models(NBM) solutions. However, will keep the Flash Flood Watch
going with the caveat that the bulk of the rain and heavy downpours
will commence after 15Z Saturday.
&&
.DISCUSSION...Skies have cleared over the area with thunderstorms
developing to the south much as expected this afternoon. With plenty
of moisture available there is a small threat for locally heavy
rains. This activity should die down this evening.
Then attention turns to the easterly wave that is moving up the back
side of the upper ridge that will bring about some interesting
weather this weekend. Plenty of moisture will be in place with PWs in
excess of 1.5 generally late tonight through Saturday. As that wave
slowly drifts north through tonight through Saturday it will be the
force triggering convection over the area. With the forcing and
moisture, some of the thunderstorms are likely to produce excessive
rains that could lead to flash flooding. This is not a widespread
steady rain event, rather scattered to numerous thunderstorms from
early Saturday morning into Saturday night. Most thunderstorms will
be good rainers and some slow movers our overly frisky ones could
produce strong winds and flooding rains, especially if the same area
gets hit more than once. Considering the forcing, the flood threat
will not be just confined to the daytime periods as scattered
nighttime convection is possible. While we occasionally get local
flash flooding on a monsoon day, the watch is issued when the threat
is elevated "above normal" over a significant area.
Given the inconsistencies in the models, pin pointing areas of
highest threat within the watch areas is challenging, especially with
convection. However, at this time it looks like the enhanced risk
will start near the southern border up to Tucson during the early
morning (pre-dawn) hours, then move north through the day to
encompass much of the forecast area during the daylight hours, then
gradually moving north during the evening into central and northern
AZ. The watch area encompasses the area and times of greatest threat
at this time and that could be adjusted through the event. As a
result of the precipitation and clouds temperatures will remain below
normal.
Sunday will be a transition day with lingering moisture but a drying
SW flow developing. This pattern provides for the potential for
increased shear which if thunderstorms develop, they could make use
of that and be quite strong. At this time storms look to be from
Tucson eastward but a lot will depend on how the next 24-36 hours
pans out. High temperatures look cooler than normal once again.
Then for next week we are in a drying pattern with temperatures
quickly jumping above normal once again. Much the same as has
happened several times in this fickle monsoon season.
&&
.AVIATION...Valid through 10/00Z.
Isolated-scattered SHRA/TSRA is expected across SE AZ into this
evening with the potential for gusty outflow winds and localized MVFR
CIGS/VSBYS possible, particularly along the International Border.
SCT-BKN clouds 10-20K FT AGL will continue a chance of SHRA/- TSRA
possible during the overnight hours as well. More widespread
SHRA/TSRA is possible Friday afternoon into the weekend. Expect gusty
and erratic surface winds near any TSRA with reduced visibilities
possible. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...The daily cycle of mainly afternoon and evening
showers and thunderstorms will continue through the forecast period
with coverage becoming a bit more widespread by Friday evening into
the weekend. Min RH values will rise to the 25-35 percent range by
the Friday evening with continued very good to excellent RH
recoveries through the weekend. Some of the storms that develop over
the weekend may become severe in nature and produce strong outflows
and heavy rain. A drying pattern is expected in the beginning half
of next week with monsoon activity diminishing temporarily. Aside
from gusty erratic winds from thunderstorm outflows, wind trends
stay light and terrain driven.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from 1 AM MST Saturday through late Saturday
night for AZZ502>515.
&&
$$
PUBLIC...Cerniglia
AVIATION....Powell
FIRE WEATHER...Powell
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