Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/12/20
Area Forecast Discussion
National Weather Service La Crosse WI
1053 PM CDT Sat Jul 11 2020
.SHORT TERM...(This evening)
Issued at 250 PM CDT Sat Jul 11 2020
First round of thunderstorms this morning developed with weak
shortwave ripples in the northwest flow aloft around 08Z, 09z, and
10Z...strengthening 12-15Z enough to produce large hail and
damage to crops across parts of Chickasaw and Fillmore Counties.
These storms have continued as they are pushing into Indiana.
Thunderstorms re-developed near Alexandria, MN late this morning
and had advanced toward Mankato by 230pm. This line of storms is
forecast to drop southeast, meanwhile, 700mb warm advection will
increase across northern Iowa with additional thunderstorm
development across northern Iowa. As the stronger shortwave
trough moves across the forecast area especially from 3pm until 8
pm. A 75kt 300mb jet is diving across the Central Plains and the
forecast area is in the left front exit region of the jet through
early evening. Expect storms to tap into deep layer shear of 40 to
50kts and MUCAPE of 3000-4500J/kg across parts of southern
MN/southwest WI into Iowa. The environment will have steep lapse
rates of 6.5 to 7.5 C/km. These factors favor severe storm
development. The SPC HRRR has MLCAPE focused more just to the west
of our county warning forecast area into central Iowa. The
outflow from the thunderstorms this morning will affect the
intensity and coverage of strong to severe storms as local
dewpoints have dropped to 65 by late morning, but is recovering.
The instability gradient has been pushed southwest...thus will be
monitoring this afternoon to see how quickly or outside of the
outflow the instability will return. At 2pm surface dewpoints are
pooled from northwest Iowa toward ALO and CID to MLI. Visible
satellite imagery shows some storms developing along this
boundary. Along and to the west of the outflow boundary,
temperatures are mostly 85 to 90 degrees with cooler 80 to 85
degree air. DVN did a special 19Z sounding. It showed very steep
low level lapse rates and SBCAPE around 2250J/kg.
The most recent radar shows a couple of clusters in southern Iowa
and in northwest Iowa with several reports of large hail 1.5 to
2.5 inches). The SPC HRRR tends to focus the organized convection
over central and eastern Iowa with a few isolated cells into
southeast MN and western Iowa. The SSCRAM/HRRR severe weather
guidance highlights the hail potential along the outflow boundary
especially toward Waterloo IA. The SPC mesographics have 40 to 45kts
of deep layer shear over our Iowa county warning area into central
Iowa. Sfc vorticity is higher near the boundary as well with an
isolated tornado threat. Isolated supercells possible
initially then more of a cluster as the storms push southeastward.
We do have a severe thunderstorm watch out for parts of southeast
Minnesota into eastern Iowa.
The convection moves out this evening with some patchy fog
possible later tonight and Sunday morning with light north winds. Lows
tonight will be comfortable in the 50s and 60s with light north
winds.
.LONG TERM...(Sunday through Saturday)
Issued at 250 PM CDT Sat Jul 11 2020
For Sunday...there is some hint that showers/thunderstorms are
possible. Our convective temperatures are only in the upper 70s
and we still have around 1 inch of precipitable water to work
with. Will want to see if there is a weak shortwave that we can
track that is forecast to drop south from SD into Iowa. We are on
the east side of the ridge and remain uncapped. May need to add
some isolated pops if we can pin down the potential better.
The mid tropospheric trough moving into southwest Canada Sunday
night into Monday will try to break down the ridge with a 40 to 50kt
low level jet increasing across the Plains...then weakening to 35kts
across Minnesota...and strengthening again to 40 to 50kts across MN.
The focus for storms Sunday night will be across North Dakota. There
may be some storms that try to develop over southern MN or western
WI Monday...however confidence is low until later Monday night and
Tuesday until there is a better push along the cold front. Will
need to watch more on the timing, however there is some stronger
deep layer shear forecast Tuesday along with precipitable water
values of 1.5 to 2 inches. The instability looks skinnier...more in
the 1000 to 2000J/kg range. Heavy rain will be a concern.
The front may push south for Wednesday or linger across our far
south. There is not good agreement in the flow for Thursday and
Friday as to more of a trough or flatter ridge. Some chance of rain
with any shortwaves in the flow...thus will need to refine timing as
we get closer.
Not as hot this weekend and into next week with highs in the 70s and
80s. Normal highs are in the lower 80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1051 PM CDT Sat Jul 11 2020
High pressure will build across the region overnight. As it does,
skies will clear. Both ceilings and visibilities will be VFR
through the period. Northwest and north winds will remain
generally less than 6 knots.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Zapotocny
LONG TERM...Zapotocny
AVIATION...Boyne
Area Forecast Discussion
National Weather Service Columbia SC
741 PM EDT Sat Jul 11 2020
.SYNOPSIS...
Drier airmass will remain over the area through the weekend.
With moderate instability and a weak trough across the area,
scattered mainly afternoon and evening showers and thunderstorms
are expected early next week. Temperatures are expected to be
at or above normal.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A dry and capped atmosphere precluding any convective concerns
over our CWA. An isolated brief shower possible early this
evening otherwise fair weather expected through the overnight.
With mostly clear skies and light winds, overnight lows expected
to be in the upper 60s to low 70s.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Sunday...An upper trough will be extending from the Great Lakes
down the eastern Seaboard on Sunday bringing shortwave energy
through the forecast area. Moisture will remain somewhat limited
across the region with precipitable water values around 1.4 to
1.6 inches with the deepest moisture east. The CAMs do not show
much convective coverage through the afternoon, but isolated
showers and thunderstorms will be possible. Kept pops in the
slight chance range or lower through the afternoon with the best
chance Sunday evening as shortwave energy moves through the
area. Another hot day is in store with highs in the mid to upper
90s.
Monday...The upper trough will remain over the region on Monday
before swinging east Monday evening with several shortwaves
passing through the area. A frontal boundary will also be in the
forecast area on Monday. Moisture will deepen on Monday with
precipitable water values rising to near 1.9 inches with the
deepest moisture east during the afternoon. Chance pops during
the afternoon period still appear reasonable with the highest
pops east. Raised pops in the east from previous forecast. Highs
in the middle to upper 90s.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
By Tuesday, the upper trough axis will be off the Southeast coast
with northwesterly flow aloft over the region. The deepest
moisture will be in the eastern portion of the area on Tuesday
with precipitable water values ranging from 1.4 to 1.8 inches.
Convective coverage should remain low Tuesday due to subsidence
over the region and limited moisture. Upper ridge will expand
over the region through the week and flatten some. Moisture will
gradually increase with diurnally driven showers and
thunderstorms expected each day with coverage increasing towards
the end of the week. Highs each day will generally be in the
middle 90s with lows in the lower 70s.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
VFR conditions expected through the TAF period.
Surface front has become stalled along the coast and the upper
trough axis has also shifted to the east which has allowed drier
air to overspread the region. Drier air in the mid level would
favor possible fog development but dewpoints mixed out into the
mid 60s this afternoon with crossover temperatures generally
around 65 degrees. Therefore it may be too dry to support a
persistent fog threat tonight. The one exception may be OGB
where drier air has struggled to reach and the crossover temp is
higher around 69 degrees. Clear skies and generally light to
calm winds with support strong radiational cooling so cannot
totally rule out possible vsby restrictions at OGB but none of
the guidance is forecasting it and HRRR keeps any fog/stratus
further to the east near the coast and the stalled boundary.
Winds will be light and variable after 15z Sunday but a
prevailing southerly direction may develop although speeds are
expected to remain below 7 knots.
.EXTENDED AVIATION OUTLOOK...
Restrictions possible in afternoon and evening convection as
well as late night/early morning fog Monday through Wednesday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Dodge City KS
827 PM CDT Sat Jul 11 2020
.UPDATE...
Issued at 827 PM CDT Sat Jul 11 2020
Reduced pop grids to 30% coverage across the SE zones for the
remainder of this evening, and this still may be too generous.
Numerous thunderstorms, some severe, continue from Beaver county
into NW Oklahoma. Cold front has cleared Kansas with NEly winds
throughout SW KS, and the cold front is currently intercepting the
storms. Despite very high instability and moisture in SW KS, with
no convergence or triggering mechanism, storms are expected to
remain south of the Oklahoma border, perhaps hugging the border at
times. Will likely coordinate with SPC regarding cancelling the
severe thunderstorm watch for Barber/Comanche counties soon.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 339 PM CDT Sat Jul 11 2020
Thunderstorm timing, placement, and severity will be the main
challenge in the very near term of this forecast. We are watching a
"cold" front push south across Kansas, which had already spawned a
couple supercell storms on the other side of the state early this
afternoon. Additional severe storms, including a supercell or two,
are likely to develop along/ahead of this front in the 4 to 6 PM CDT
time frame. The hourly HRRR model has been fairly consistent today
with timing and development of convection, supporting an area
including our southeastern 5 or so counties, focused especially on
the Red Hills region. The deep layer shear is supportive of
supercell structures with 6km AGL winds out of the northwest 35 to
40 knots. The low level winds will not be all that great, but storm-
relative low level winds will certainly be sufficient enough to
maintain supercell structures for at least an hour or two this
evening, before storms grow upscale into a larger cluster
around/after sunset. When this happens, though, most of the activity
should be in Oklahoma as the front continues to push south.
No changes were made to the Heat Advisory, as temperatures warmed
into the lower to mid 90s across much of the advisory area with very
high dewpoints in the lower to even mid 70s degF. This resulted in
heat indices of 105 to 108F. The front will continue to push south
tonight with weak high pressure building south. This front will
provide some relief to the excessive heat/humidity, as Sunday
afternoon temperatures will top out in the 92-95F range with lower
dewpoints of upper 50s to mid 60s. The highest dewpoints tomorrow
afternoon will likely be across the far southwestern Kansas in the
increasing post-frontal upslope that will develop. Thunderstorms
will develop out across eastern Colorado in the typical terrain-
favored areas which will then likely grow upscale as outflows
develop and approach far western Kansas. We will carry some Slight
Chance to Chance POPs out across the far western counties as a
result.
.LONG TERM...(Sunday night through Saturday)
Issued at 339 PM CDT Sat Jul 11 2020
Last week, it was looking like we were about to enter a fairly bad
heat wave across southwest Kansas. This will most likely not develop
near as early as thought. There is increasing consensus among the
various longer term, global model solutions of a stronger, more
amplified polar jet moving across the northern CONUS and southern
Canada, which will bring another decent polar front down into the
Central Plains mid next week. Tuesday could end up being very hot
just ahead of this front, but there are still quite a bit of timing
uncertainties. The uncertainties then become even greater going into
later next week as the GFS and ECMWF are at odds with placement and
strength of the summer subtropical ridge, along with configuration
of the northern polar jet. It still looks like prolonged (multiple
days) excessive heat may develop, but again, much later than
previously thought more than likely (starting around 16-17 July).
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 513 PM CDT Sat Jul 11 2020
VFR will continue through this TAF cycle. A weak cold front had
cleared all airports as of 22z, with modestly gusty NE winds. Any
convection that develops along this boundary will favor the OK/KS
border, southeast of the terminals this evening. As such, kept all
the 00z TAFs dry. VFR/SKC will prevail into Sunday, with the
exception of a likely midlayer cloud deck near LBL around 12z Sun.
Light NE winds are expected overnight, trending SEly and modestly
gusty after 15z Sun.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 68 93 68 98 / 10 10 20 0
GCK 66 94 67 98 / 10 10 20 0
EHA 68 94 68 101 / 10 20 30 10
LBL 68 95 68 101 / 10 10 20 0
HYS 64 92 68 95 / 0 0 0 0
P28 72 93 69 96 / 30 0 20 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Turner
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Turner
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
642 PM CDT Sat Jul 11 2020
.Discussion...
Issued at 1254 PM CDT SAT JUL 11 2020
Severe weather will be the main impact in the next 12 hours with a
favorable setup over eastern KS and western MO. A shortwave trough
and jet streak over Nebraska help enhance a favorable synoptic set
up for our region today as a warm front extends through central
Kansas into a developing cold front over southern Nebraska. This
boundary will become the main initiating boundary this afternoon as
it surges to the SE. CAM solutions have a wide variation of
solutions this afternoon into this evening. Conceptually they all
have similar solutions, but vary in storm mode and initiation
time/place. We are leaning towards the RAP solution as it seems to
have the best dewpoint solution as the HRRR mixes out way too much
in the afternoon. This has a dramatic effect on the MLCAPE and why
that model keeps trying to weaken storms over the KC Metro. We don`t
see this really happening and once the storms initiate over NE
Kansas they should have a favorable atmosphere to work with
upstream.
Storm motion will be off the boundary, but not much quicker than the
boundary motion itself. This combined with effective shear of 50kts
perpendicular to the boundary should lead to discrete cells
initially which may last a few hours before becoming multi-cellular
as the front starts to speed up. RAP sounding hodographs indicate
mostly straight hodograph, but there is some curvature if storms can
become right movers, leading to possible isolated rotating updrafts.
With plenty of shear, steep lapse rates of 8C/km, and MLCAPE 2500-
3000J/kg large hail will be a major threat. Some hail could be
greater than 2" if rotating updrafts can develop. DCAPE will be high
(1500J/kg or greater) indicating steep low level lapse rates and dry
air in the mid levels. This will increase wet microbursts
possibility and add damaging winds (60-70mph) to the storm impacts.
The main threat for the KC Metro will be 4-6PM. Storms may become
multi-cellular as they progress southward from the KC Metro, which
may increase the wind threat if they can develop an organized cold
pool. This will likely be more of an issue for Springfield, but may
occur in our southern counties as the transition begins. Most of
these impacts will stay confined to south of the Missouri River,
with one caveat of a second possible round over north central
Missouri. CAMs are indicating that an MCS may form up over central
Iowa in the evening and slide into our area after sunset, possibly
interacting with the boundary already established across that area.
A surging post-frontal trough at this time will also possibly
enhance the W-E oriented boundary over central Missouri for a late
round of storms 9PM-12AM. There may still be enough MUCAPE and shear
to see some isolated severe storms with elevated hail and strong
wind threats. Uncertainty will play a factor with these storms as we
do not know exactly how the first round will work over the area and
could alter the second round.
Northerly flow with increasing pressure and upper level ridging will
help bring in a cooler airmass Sunday with high temperatures in the
mid to upper 80s. As the high pushes to the east, slightly warmer
air will move into the region for Monday with highs reaching into
the 90s, but dewpoints will return to the 70s bringing the humidity
with it. A cold front will form ahead of a shortwave trough over the
Northern Plains Tuesday morning into the afternoon. With the front
oriented SW-NE over NE/IA a thermal ridge will form over our area.
This will climb our temperatures back into the low to mid 90s with
heat indices above 100 degree returning to the area. As storms form
along this boundary Tuesday evening it sets up a possible MCS
scenario over northern Missouri Wednesday morning. A shortwave
trough from the west will override this boundary Wednesday over
northern Missouri and increase PoP and storm chances that afternoon.
This boundary sort of stalls over the region Thursday through Friday
bringing rain chances off and on throughout that period.
&&
.Aviation...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at |640 PM CDT SAT JUL 11 2020
VFR conditions with light northwesterly winds next 24 hours over
the terminals.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Barham
Aviation...Adolphson
Area Forecast Discussion
National Weather Service Grand Forks ND
1000 PM CDT Sat Jul 11 2020
.UPDATE...
Issued at 958 PM CDT Sat Jul 11 2020
Skies clearing nicely over the area. Once exception is a cloud
area moving southeast from Manitoba toward the Langdon area. One
or two showers remain with this north of the border. May need to
have isold shower Langdon area for a bit longer tonight.
&&
.SHORT TERM...(This afternoon through Sunday night)
Issued at 326 PM CDT Sat Jul 11 2020
We continue to monitor potential for non-supercell funnel/tornadoes
over parts of west central MN this afternoon.
Mid level circulation associated with enhanced vorticity environment
and "cold core" funnel reports (brief touchdown) is still moving out
of Otter Tail County based on latest satellite trends. Until this
circulation completely moves out of our area we will still see
potential for more of funnels with these showers/storms in west
central MN. It had slowed down a little, but it still looks to exit
our CWA within the next 1-2hr period. On the back side of this area
of showers/t-storms where was some clearing and a little better
lapse rate environments and RAP analysis is showing high values of
both non supercell tornado parameter and stretching potential. This
is offset from region of higher mid level vorticity and may be more
of a landspout tornado signal. Surface analysis is showing weak
convergence near the line of showers/storms from Clay to Otter Tail
County lined up with these parameters. Window for either landspout
or "cold core" risk still appears to be through 5 PM, so SPS was
extended to cover as we will continue to be monitoring.
Tonight-Sunday: Quieter weather expected as shortwave ridging
transitions over our CWA, along with surface high pressure. With more
sunshine and a little m ore moderation of air mass aloft due to
southeast flow returning we should have highs in the lower 80s
Sunday. Expecting dry conditions at least through Sunday evening,
though the next approaching system could bring increasing chances
late Sunday night to the Devils Lake basin.
.LONG TERM...(Monday through Saturday)
Issued at 326 PM CDT Sat Jul 11 2020
The main impact in this time frame will be the severe and heavy
rainfall threat on Monday into Monday night. Synoptic scale aspect
will be provided by a long wave trough moving into the Northern
Plains. Warm air and moist air will be advected into the area Monday
providing an unstable environment. This moisture will be enhanced
locally by moist soils and evapotranspiration. This leads to
precipitable water values around 1.5 inches which is in the 97th
percentile in NAEFS. This instability and forcing combined with bulk
shear in excess of 50 knots will support all modes of severe
weather. Model guidance continues to suggest that the highest
rainfall will occur in the northern Red River Valley into north
central Minnesota. This will vary significantly though since the
forecast is convective in nature.
After Monday there are a few more chances for rain and thunderstorms
in the mid to late week. There is a lot of spread between model
guidance for timing and magnitude so confidence is low on the
details of precipitation at this time. Temperatures will be near to
above average over the next week based on NBM temperature
percentiles.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 710 PM CDT Sat Jul 11 2020
VFR thru the pd. Few CU to clear overnight then SCT CU Sunday with
daytime heating. Maybe BKN at times. Light winds overnight turning
more southwest or south near 10 kts in E ND by Sunday aftn. Patchy
ground fog is psbl over parts of northwestern or west central MN
but short range models show limited in coverage and therefore not
put in any TAFs.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...Riddle
SHORT TERM...DJR
LONG TERM...NC
AVIATION...Riddle
Area Forecast Discussion
National Weather Service Goodland KS
537 PM MDT Sat Jul 11 2020
.UPDATE...
Issued at 530 PM MDT Sat Jul 11 2020
Increased clouds in southwest portion of the forecast area towards
12z and added patchy fog. Hi-res models including HRRR show
stratus and patchy visibility reductions streaming northward early
Sunday morning, gradually dissipating by mid morning. Impacts
expected west of a Yuma to Leoti line.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 227 PM MDT Sat Jul 11 2020
Across the Tri State region this afternoon, skies are ranging widely
from partly sunny to sunny. Slow moving frontal boundary has
triggered a few rw/trw south of the Interstate with an eastward
movement. There is also scattered high clouds moving thru portions
of the northern CWA. Temperatures are currently ranging mainly in
the 80s with a few spots around 90F. High pressure building off the
Rockies is giving the region a N/NE flow, gusting at times up to 20-
30 mph.
For the remainder of the afternoon into the evening hours, looking
for any remaining showers to push east of the CWA before sunset,
with surface ridge to our north transitioning east of the CWA.
Going into Sunday, strong upper ridge remains across the southern
portion of the country providing a persistent downslope flow over
the area, allowing for yet another hot day for the CWA. By the
afternoon hrs, a shortwave is expected to traverse the northern edge
of the ridge setting up along the Front Range. Convection is
expected to form ahead of the trough from the late afternoon into
the evening hrs before tapering off. Instability over areas from Hwy
27 and points west will warrant the mention of potential strong to
severe trw potential. SPC has a Marginal Risk out as a result for
the late afternoon/early evening time frame. Besides the wind/hail
threat, PW values are ranging at least an inch during expected
precip time, so locally heavy rainfall/ hydro concerns will have to
be monitored.
On Monday, a strong shortwave works east off the Front Range into
the Plains region with a similar timeframe to Sunday`s precip. Areal
extent is much more than Sunday`s and with better instability.
Marginal/Slight risks are out from SPC, with areas north of Hwy 36
seeing best chance for worse conditions. Again, PW values will be
high, so hydro/flooding concerns will have to be monitored. Possibly
for convection to merge into a line late in the period, allowing for
wind/hail threats to shift to more wind issues for the latter
portion of the timeframe.
For temps, above normal heat again for both Sunday and Monday with
90s for highs expected, warmest Monday. Overnight lows will be in
the 60s. note...any convection that does develop could locally
impacted forecast highs/lows.
.LONG TERM...(Tuesday through Saturday)
Issued at 140 PM MDT Sat Jul 11 2020
For next Tuesday on into the beginning of next weekend, the strong
upper ridge which the models have carried across the southern Plains
over the last few days if forecasted to retrograde as the week
progresses, with some amplification into the western portion of the
country by Friday/Saturday.
Several shortwaves do traverse the northern periphery of the upper
ridge during this time, giving the region the best chance at seeing
precipitation, as each day some portion of the CWA will see the
chance for rw/trw. A cold front traversing the region around the
midweek timeframe will give the area the best chance for decent
areal coverage for precip.
Besides the expected wind/hail threats, PW values during the week
will range between 1.00-1.50" over almost the entire CWA. This will
bring up locally heavy rainfall/hydro concerns area-wide and will
have to be monitored each day next week.
A persistent westerly downslope flow thru the week with a shift to
the NW by the weekend will guarantee most the extended for near to
above normal high temps ranging in the 90s. The expected areal
coverage of clouds/precip expected for Tuesday/Wednesday, along with
the frontal passage will allow for slightly cooler conditions with
80s on tap. The overnight lows will be affected as well with 50s for
Tuesday night, but transition back to what has been happening over
the past several days with lows 60s west to the low 70s east.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 530 PM MDT Sat Jul 11 2020
At KGLD...VFR expected through tonight, then patchy fog and low
clouds possible towards 12z as stratus returns northward.
Confidence medium at this point, and impacts should be limited to
a few hours near 12z Sunday morning. Isolated storms possible very
late in the TAF period as they move out of Colorado, but limited
coverage will preclude a mention in the TAF at this time.
At KMCK...VFR expected through the TAF period. Light surface winds
tonight will increase from the south by 18z Sunday.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...024
SHORT TERM...JN
LONG TERM...JN
AVIATION...024
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
853 PM EDT Sat Jul 11 2020
.SYNOPSIS...
A low pressure system and cold front affect the region on
Sunday. High pressure will then build into the Ohio Valley by
Monday, bringing a return to dry weather.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Line of convection has pushed south of the fa, leaving some
post storm stratiform precipitation to affect the Tri-State for
a few hours.
What will happen the rest of the night gets murky and the
confidence is low. The HRRR which is handling the system the
best right now, drops current pcpn south, but then brings
another weakening shot into the Tri-State between 09-12Z. The
RAP meanwhile keeps this pcpn lingering all night. The 18Z NAM
has a different idea as it drops current pcpn south, but then
brings a cluster of storms out of nrn IL into IN between 09-12Z.
Leaned towards the HRRR solution, but as mentioned confidence is
low.
The Tri-state is rain cooled into the mid to upper 60s and will
probably remain there for the overnight. Other locations will
gradually cool to those values by morning.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
A stronger short wave in the northwest flow aloft will accompany
weak low pressure and a cold front on Sunday to bring an
increasing chance of showers and thunderstorms. Best coverage
should coincide with the mid to late afternoon hours as moderate
instability develops. As a result, could see a few strong
perhaps severe storms. Damaging winds will be the main threat
with perhaps some isolated large hail across the southern half
of the CWFA. Highs will be mainly in the lower 80s.
For Sunday night, the entire weather system will push east/southeast,
allowing pcpn to taper off from northwest to southeast. Drier
air will then filter into the region overnight. Lows will
generally bottom out in the lower 60s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
High pressure will be in place for Monday and move east of the
forecast area for Tuesday. With northerly flow, expect Monday to
be the coolest of the long term with high temperatures ranging
from the upper 70s to the middle 80s. High temperatures on
Tuesday will be near normal in the low to middle 80s with
continued dry conditions.
The heat and humidity will begin to build for Wednesday and the
remainder of the week. Multiple systems will move through
during this time allowing for daily thunderstorm chances.
Heat index values across at least a portion of the area are
expected to reach into the middle to upper 90s beginning on
Wednesday. There will be the potential late week for some heat
index values to reach near 100. Due to uncertainty in exact
thunderstorm timing this far out and the impact on temperatures,
decided to hold off on heat mention in the HWO at this time.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Line of thunderstorms affecting CVG/LUK raced southeast quicker
than thought earlier. Latest run of the HRRR has this covered
the best and dives the storms south of the region in the next
few hours. So pcpn will affect CVG/LUK for the first hour or
two of the period, then expect dry conditions for the rest of
the night. Some convective blowoff will affect the tafs for the
first few hours, before scattering out.
During the day Sunday, a digging H5 s/w will swing across the
tafs. Showers and some thunderstorms will develop between
12-15Z. Best forcing and lift looks like it will set up across
the southern tafs, so coverage will be most widespread there.
Cold front will push into the Western tafs late in the period,
beginning the process of push the convection to the east.
OUTLOOK...Thunderstorms to linger into Sunday evening.
Thunderstorms possible Wednesday night into Thursday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Hickman
NEAR TERM...Sites
SHORT TERM...Hickman
LONG TERM...Novak
AVIATION...Hickman/Hogue/Sites
Area Forecast Discussion
National Weather Service Indianapolis IN
1033 PM EDT Sat Jul 11 2020
.UPDATE...
The AVIATION Section has been updated below.
&&
.SYNOPSIS...
Issued at 148 PM EDT Sat Jul 11 2020
A pair of upper level weather disturbances will push across
Indiana tonight and on Sunday. This will bring chances for
showers and thunderstorms to Central Indiana to close out the
weekend.
High pressure is then expected to build across the area for the
start of the work week...providing dry weather with slightly below
normal temperatures.
A warm front is expected to push across the area on Tuesday. This
will usher hot and humid air back to Central Indiana...along with
chances for daily showers and thunderstorms for the middle and
latter part of the work week.
&&
.NEAR TERM /Tonight/...
Issued at 148 PM EDT Sat Jul 11 2020
Surface analysis early this afternoon shows high pressure in place
across the lower Mississippi river Valley and Low pressure over
upstate NY. This was resulting in a light W-NW flow across
Indiana...with dew point temps mainly in the low to mid 60s. A
convective complex was found over eastern IA and Nrn IL...pushing
SE within the flow aloft.
The air mass ahead of the approaching convection and subtle short
wave will be marginally favorable for convection. Forecast
soundings show CAPE around 1500 J/kg along with convective
temperatures in the upper 80s which should be reached. HRRR shows
scattered convection arriving late this afternoon and into the
early evening within the NW flow aloft. Thus will focus some pops
late this afternoon and early this evening given the impact of
daytime heating. Better forcing looks to arrive overnight in
association with the approaching short wave over the upper
Midwest. Time Height at that time suggest deep moisture and lift
in play. HRRR at that time also suggests more widespread
precipitation overspreading the area. Thus will once again trend
pops higher after midnight and into early Sunday as this feature
pushes across the area. Given the expected clouds and possible
precip...will trend lows at or above the NBM.
&&
.SHORT TERM /Sunday Through Tuesday/...
Issued at 148 PM EDT Sat Jul 11 2020
GFS and NAM show the short wave departing on Early Sunday
morning. However forecast soundings by Sunday afternoon again
show favorable conditions for convection with steep lapse
rates...CAPE over 2500 J/KG and pwats over 1.5...and convective
temps in the lower 80s. Thus will keep some pops in the forecast
on Sunday through the hours of Diurnal heating. However of
note..any afternoon convection should be much more isolated.
Forecast soundings show good subsidence within the column on
Sunday afternoon into Sunday Night....as mid levels show good
drying. Meanwhile at the surface high pressure is expected to
build across Indiana and the Great Lakes...lowly passing across
the area through Tuesday. As the high pressure passes along with
the NW flow in place aloft on the lee side of an upper ridge over
the plains...more subsidence will be expected through Tuesday.
With Northeast winds expected around high...Dry weather will be
expected on Monday through Tuesday with slightly below normal
temperatures.
&&
.LONG TERM /Tuesday Night to Saturday/...
Issued at 234 PM EDT Sat Jul 11 2020
Upper high pressure will expand into our area through the long
term. Recent models continue to trend with the high not moving
into the area quite as much as previous runs, thus have also been
trending towards highs only getting into the low 90s rather than
mid 90s or slightly higher. This will also place the region under
more zonal flow as well as on the periphery of the high... in
these cases, slight upper wave and mesoscale disturbances become
more influential for rain chances. These conditions lead to lower
confidence on specific rain events through the long term as models
fluctuate. Have generally accepted guidance, but did cap PoPs at
chance.
&&
.AVIATION /Discussion for the 12/03Z TAF Update/...
Issued at 1028 PM EDT Sat Jul 11 2020
Update...
Shifted timing of second round of storms to Sun 06Z at KIND.
Previous Discussion...
Showers and thunderstorms will continue to impact KHUF and KBMG
through Sun 01Z. VFR will be the predominant flight category
outside of any storms though, just expect quick deterioration to
MVFR or worse in any showers and thunderstorms. Elsewhere, the
lull in activity has already set in across KLAF and KIND, and KHUF
and KBMG should also quiet down for awhile by late evening.
However, re-development is possible again overnight as the upper
wave passes over central Indiana. As a result, will have to carry
mention of VCTS again overnight and tomorrow morning. Meanwhile,
winds will shift from the southwest to northwest and will be
relatively light outside of any convection.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...Puma
NEAR TERM...Puma
SHORT TERM...Puma
LONG TERM....KH
AVIATION...TDUD
Updated for 00Z Aviation Forecast Discussion below.
PREV DISCUSSION... /issued 630 PM CDT Sat Jul 11 2020/
DISCUSSION...GOES-16 Satellite trends place a Mesoscale
Convective System over Southeast Kansas this evening. Regional
WSR-88D radar trends and Short term models/Convective Allowing
Model Solutions (CAMs) indicate the aforementioned MCS should stay
to the west of the Mid-South with the main focus for showers and
thunderstorms over our area located over Central Iowa and
Illinois/Indiana. This latter convective activity may be the
focus for nocturnal convection overnight across the Mid-South.
Thus, have trimmed back rain chances to mainly the overnight
hours. Rain chances have also been adjusted into tomorrow to
account for these model trends.
Updated grids already sent.
CJC
PREV DISCUSSION... /issued 327 PM CDT Sat Jul 11 2020/
DISCUSSION...
A hot day ongoing across the Mid-South at 3PM. Skies are generally
clear, with a weak CU field mainly over Eastern Arkansas. Air
temperatures are in the low to mid 90s across the area, with heat
index values in the upper 90s to lower 100s. So far, Clarksdale,
Mississippi is the only location to eclipse the 105F mark. A heat
advisory remains in effect through 7PM for a handful of counties
in southeast Arkansas and a couple in northwest Mississippi.
Convective Allowing Models (CAMS) suggest a couple of isolated
showers and thunderstorms are possible before sundown tonight, so
carried a slight chance through this period. An MCS, currently
near Kansas City, will translate downstream into the Mid-South
sometime after midnight tonight. A couple of the models show the
main convective system breaking apart into a couple segments,
which could reduce the overall severe threat. However, if a mature
and organized cold pool can maintain, a more widespread wind
event could occur as the atmosphere will remain loaded overnight.
Will continue with current wording in the HWO of a few strong to
severe thunderstorms are possible tonight and into the overnight
hours.
Slightly cooler temperatures can be expected on Sunday due to
increased clouds and precipitation. It looks as though areas north
of I-40 will remain dry tomorrow afternoon, with lingering showers
and thunderstorms possible south of the corridor. A few storms in
the afternoon could be strong, but overall threat looks rather
marginal at this point. A weak cold front is expected to push
through the Mid-South tomorrow evening. This front will bring
slightly drier air to portions of west Tennessee, where lows
will fall into 60s again.
Monday will be dry and seasonal. Expect highs in the lower 90s
with heat index values in the mid to upper 90s.
The upper level ridge out west will nudge its way into the Lower
Mississippi Valley on Tuesday and build into the Mid-South through
at least Thursday. Models have now trended slightly weaker with
the ridge, which has reduced high temperatures by a couple of
degrees. Albeit, air temperatures will be in the mid 90s with
heat index values around 105F areawide. Wednesday and Thursday
look to be the hottest days of the period, with at least a few
locations meeting or eclipsing the 110F heat index mark. The
ridge appears that it will weaken by next weekend, which will
hopefully end the heatwave and bring us some precipitation.
AC3
&&
.AVIATION...
00Z TAFs
Main concern remains overnight TSRA chances, as the Midsouth
remains downstream of two TSRA source regions late this afternoon.
One of these regions is east KS, the other eastern IA/western IL.
Midlevel model thickness fields suggest the former will pass off
to our west through AR through the overnight. The IL complex will
take a more easterly path toward the TN River, with less favorable
inflow of low level instability. A few high resolution convection-
allowing models depict the two convective segments joining up
toward 11Z, passing through MEM. This scenario is far from
certain, hence only a PROB30 near or shortly following sunrise.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Paducah KY
632 PM CDT Sat Jul 11 2020
.UPDATE...
Issued at 632 PM CDT Sat Jul 11 2020
Updated Aviation discussion for the 00 UTC TAF issuance.
&&
.SHORT TERM...(Tonight through Monday night)
Issued at 258 PM CDT Sat Jul 11 2020
Main concern for tonight continues to be the chance for severe
thunderstorms. All but the extreme SE portion of our FA is under a
Slight/Level 2 Risk of severe thunderstorms tonight. Models trends
indicate the chance for an initial round of thunderstorms this
evening over SW IN and adjacent areas of SE IL. The ECMWF, NAM and
HREF suggest one round in this region by early evening with another
overnight whereas the HRRR keeps this region largely dry thru
tonight, with convection from Petersburg IN northeastward. The GFS
has the initial round in the NE tonight but generates little QPF
elsewhere except SEMO. Given the weighted guidance, will go with
slightly higher POPs (50-60%) over SW IN, SE IL and adjacent W KY
areas, with high chance POPs elsewhere for tonight. Feel with a
fairly significant 500mb shortwave progressing SE across the FA,
POPs in this range are warranted.
The best chance of severe weather per the SREF/HREF guidance will
likely be from around 03Z-09Z (NW part of FA to W KY), despite
lessening instability as mid level lapse rates and winds fields
remain available to some degree. These parameters looks more
favorable over SE MO, SW IL and into the purchase region of W KY
than points further E or NE.
By Sunday morning, the convection should have advanced SE and be
mostly limited to W KY and SW IN where the Day 2 Marginal Risk
covers. Feel the chance of severe weather will be small, albeit non
zero, for Sunday morning, and remaining convection should be mostly
east of the FA by afternoon.
Surface high pressure building S from the western Great Lakes region
will begin to scour out the air mass across the FA by Sunday night
as winds become northwesterly Sunday afternoon and northerly Sunday
night. Surface dewpoints are expected to be very pleasantly low
Monday with afternoon values AOB 65 which is fairly rare for mid
July. The dry, pleasant July weather will continue through Monday
night when lows will fall into the mid 60s for the second night in a
row. Some locales could dip into the lower 60s.
.LONG TERM...(Tuesday through Saturday)
Issued at 258 PM CDT Sat Jul 11 2020
Models continue to trend wetter for next week. A weak mid/upper
level ridge will be over the middle Mississippi and lower Ohio
valleys on Tuesday. Models take the ridge east faster now, which
allows trofs to move across our region Wednesday into early
Thursday, and Thursday night into Friday. This results in on and
off chances of showers and thunderstorms across our entire region
late Tuesday night through Saturday, with the best chances mainly
east of the Mississippi River. Confidence in timing is not great at
this point, thus having chances in every period, but some fine
tuning as models get a better handle on things may result in a dry
period or two.
The wetter trend also tones down the heat issue a little. Models
have taken afternoon highs down a couple of degrees each day, with
readings now in the lower to middle 90s. These values, combined
with expected dew points in the middle 70s, give afternoon heat
indices in the 100 to 107 degree range.
&&
.AVIATION...
Issued at 632 PM CDT Sat Jul 11 2020
Main concern with this TAF package will be the potential for
isolated to scattered thunderstorms overnight into Sunday.
Confidence is not high enough to include TSRA at any terminal,
but have included periods of VCTS. At KEVV/KOWB, additional
isolated to scattered thunderstorms may develop in the late
morning and linger into the early afternoon, so maintained VCTS
through 18z Sunday there. Cigs will remain VFR.
Outside of thunderstorms, expecting southwest winds tonight at 5
kts or less, becoming variable at times. Winds will become WNW
after 15-18z, at 5-10 kts.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...DWS
SHORT TERM...RLS
LONG TERM...RST
AVIATION...DWS
Area Forecast Discussion
National Weather Service Phoenix AZ
449 PM MST Sat Jul 11 2020
.UPDATE...
Updated aviation discussion.
&&
.SYNOPSIS...
Abnormally strong high pressure building over the area into early
next week will result in excessive heat with lower elevation high
temperatures rising into the 115 to 119 degree range. Isolated
showers and thunderstorms will be possible this afternoon and
evening mostly over areas east of Phoenix. Extreme temperatures
should subside early next week, but temperatures likely will
remain above normal.
&&
.DISCUSSION...
Radar this afternoon showed convection firing up along the Mogollon
Rim. KFSX showed several outflows drifting toward/into southern
Gila County. The latest HiRes guidance show additional showers and
thunderstorms developing along these outflows as they push toward
the west and southwest. HREF guidance shows PWAT values generally
remaining between 0.8 to 1.2 inches across south-central Arizona
this afternoon and evening, but the lower levels of the atmosphere
will remain dry. Rainfall amounts with these storms are expected
remain light overall for most areas, though a few isolated higher
amounts aren`t out of the question. HRRR remains the most
aggressive as it tries to develop convection along the outflows as
they push into eastern parts of Maricopa County and potentially
into eastern parts of the metro. Can`t rule out a few isolated
showers/thunderstorms making as far west as eastern parts of the
metro. Main threats with any storms will be gusty outflow winds
and lightning, though localized areas of blowing dust aren`t out
of the question.
The main story will be the excessive heat. Today will be one of the
warmest days of the year as afternoon highs are expected to top out
around 112-116 degrees across the lower deserts today. Temperatures
over the next several days will be the warmest temperatures of the
year and perhaps some of the warmest temperatures in 2-3 years.
Overall, there has been very little change to the temperatures as
model guidance remains in good agreement in regards to the magnitude
of the ridge and the associated heat. Mid-tropospheric heights will
peak today around 597-600 dm today across the state. However, the
hottest day looks to occur tomorrow when 850 mb temperatures hit its
peak. Afternoon highs for Sunday will be in the 115-119 degree range
across the lower deserts.
The anticyclone bringing the current excessive heat will begin
drifting eastward early next week. This will result in a more
pronounced southwesterly flow and somewhat of a cooling trend,
though temperatures will likely remain above normal for the
foreseeable future. EPS and GEFS guidance doesn`t highlight any
specific day to be more favorable for convection next week. For now,
POPs remain low for much of next week.
&&
.AVIATION...Updated at 2350Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Watching outflows boundaries off to the north/east of the metro
area and the potential they will move in during the next 2-3
hours. Overall the storms which spawned the outflows were not
particularly strong, and the current forward speeds of the
outflows is around 10 kt (suggesting gust potential of around 20
kt). Given that the overall trend of storm activity will be
downward and the outflows will be having to move downhill against
the broad southwesterly flow across the Phoenix area, expecting
the outflows to weaken as the move in. Latest TAFs were nudged
down a bit with wind shift speeds, and timing slowed a little bit.
Also removed any shower wording. Once the outflow is in/through,
winds will weaken thereafter and we could be looking at fairly
light/variable winds overnight.
Southeast California/Southwest Arizona including KIPL and KBLH:
Mid level clouds have moved out and broad southerly flow is coming
up out of the Gulf of California and into the lower Colorado River
Valley. Do anticipate some weak downslope winds to develop later
this evening, with a return of southerly winds on Sunday.
&&
.FIRE WEATHER...
Tuesday through Saturday:
Dry conditions and well-above normal temperatures can be expected
Monday with lower deserts seeing highs in the 112-117 degree
range. Some cooling can be expected during the Tues-Fri period.
Daytime minimum humidity values will be around 10-20% for most
places while overnight recoveries will rise into the 30-50% range
for most places, with the highest values over the high terrain.
Wind speeds will be light most days, outside of typical afternoon
breezes up to 20-25 mph, with directions following local terrain
influences. Moisture will fluctuate some, but the atmosphere will
likely remain too stable for much thunderstorm coverage in most
locations. Gila County will stand the best chance of seeing some
isolated activity throughout next week.
&&
.CLIMATE...
Record Daily Maximum Temperatures
Date Phoenix AZ | Yuma AZ | El Centro CA
---- ----------- ------- ------------
7/11 118 in 1958 | 118 in 1958 | 117 in 1975
7/12 115 in 2009 | 119 in 1939 | 118 in 1964
7/13 114 in 2005 | 115 in 1983 | 118 in 1939
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Monday for AZZ530>563.
CA...Excessive Heat Warning until 8 PM PDT Monday for CAZ560>570.
&&
$$
DISCUSSION...Smith/Hodges
AVIATION...Iniguez
FIRE WEATHER...Smith/Hodges/Feldkircher
CLIMATE...MO