Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/12/17
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
537 PM MDT Tue Jul 11 2017
.AVIATION...
00Z TAF CYCLE
Today`s crop of isolated to scattered showers and thunderstorms has
favored the higher terrain of western and northern New Mexico.
Storms will continue to drift off of the higher terrain gradually
filling into adjacent lower elevation areas and valleys through the
evening. Prevailing breezes will be light to moderate through sunset
with sudden, strong, and erratic downbursts possible from any nearby
shower or storm. Any reductions in visibility or ceilings from
downpours will be brief. Most of the storm activity should diminish
before midnight with a fairly similar placement of storms expected
again on Wednesday.
52
&&
.PREV DISCUSSION...300 PM MDT Tue Jul 11 2017...
.SYNOPSIS...
An active weather pattern expected through the next week with daily
rounds of showers and thunderstorms. However, there will be subtle
changes in cell motion and focus areas for wetting rainfall. The
upper high center will drift to the east for the next couple of
days, opening up a more plentiful stream of moisture over western
and northern New Mexico. By the weekend, the high center will drift
back to the Four Corners and Great Basin, allowing drier air to push
back into east eastern and central New Mexico. Next week the upper
high center may return to the Plains states, with showers and storms
becoming more numerous.
&&
.DISCUSSION...
Storm motion has shifted today, from southwest and south on Monday,
to the northwest and north today. As the afternoon/evening
progresses, a few storms may make their way into the Northeast
Highlands and Plains, although they will have to compete with the
drier air noted on satellite imagery working it`s way westward. HRRR
hangs onto some activity over the West Central and Northwest, as
well as the east slopes of the Sangre de Cristo mts after midnight.
Expect showers and storms to fire over the western and northern
higher terrain Wednesday then drift north and east. East central and
south central areas look to be least likely to see convection. For
Thursday, NAM12 suggests a surface boundary stretched over the
northeast will act as a focus for showers and storms which then
propagate south and westward. Thursday`s high temperature guidance
especially over ne NM is several degrees cooler than what was in the
inherited grids, so went ahead and made some adjustments, although
did not go quite as cool as the MET guidance. That said, high
temperatures don`t stray too far from average for the next 7 days.
Friday may become a transition day, with the upper high center
reforming over the Four Corners and Great Basin, with the east
central and southeast drying and convection shifting back to the
northwest third to half of the forecast area. The high stays put
over the weekend, then drifts back over the Plains states, allowing
for showers and storms to become more widespread and numerous.
&&
.FIRE WEATHER...
The main mid to upper level high pressure system will remain east of
NM through Thursday with a secondary high over Arizona. The weakness
across New Mexico will allow some monsoonal moisture to seep
northward. This moisture will be focused across western NM for the
remainder of today, will shift slightly eastward Wednesday, and will
be elongated from west central to northeast NM on Thursday. High
terrain areas will remain favored for storms, but storm motions will
vary day-to-day, and no particular day will they be greater than 10
mph or so. Thus, fairly slow moving, so some areas should pick up
decent wetting rains. These wetting rains will still be fairly
spotty overall though.
By Thursday night and especially Friday, the upper high will build
back over the Four Corners region and perhaps will slide westward
over southern Utah next weekend. Overall, there will not be much
change day-to-day in terms of shower and thunderstorm coverage. It
looks like low level Gulf moisture may seep up from the south or
southeast with the upper high out of the way.
With daily rounds of showers and thunderstorms expected,
temperatures will generally decrease through the next several days
thanks to the precipitation and cloud cover. Humidity values,
however, will generally creep upward. Light winds will persist,
which will result in pockets of poor ventilation.
34
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service La Crosse WI
638 PM CDT Tue Jul 11 2017
.SHORT TERM...(This evening through Thursday night)
Issued at 213 PM CDT Tue Jul 11 2017
Early this afternoon, a warm front extended from northwest Iowa
into east-central Iowa and northern Illinois. This front has been
making some slow northward progress and just how much more it will
make will have a big impact on where the heavy rain falls tonight.
Water vapor satellite shows a weak short wave trough moving across
the Missouri River Valley. A line of showers and isolated storms
has develop ahead of this wave and north of the warm front across
northern Iowa. None of the hi-res meso-scale models are handling
this activity very well as they are all underdone or do not even
indicate this activity. The 11.16Z HRRR is probably the closest to
reality but it shows this dying off rapidly this afternoon which
seems to contradict radar data which suggests it is in a steady
state. If this activity continues through the afternoon, it should
serve to delay the northward movement of the front so that by
tonight it could end up right across the forecast area. The 11.12Z
models all continue another short wave trough coming out of the
Dakotas and across Minnesota into northern Wisconsin tonight. This
wave does look to come close enough to produce weak pv advection
in the 500-300 mb layer. This forcing will be enhanced by the low
level forcing with 5 to 10 ubar/s of up glide expected on the 310K
isentropic surface. The low level moisture transport will increase
this evening and be focused right on the front. This is expected
to be more than sufficient forcing to generate another round of
showers and storms. See the hydro section below for more details
on the heavy rain threat. This convection should form rather
quickly late this evening and then blossom into a complex that
moves east across the area overnight. Some threat for damaging
winds and large hail, especially during the evening hours. Ample
amounts of ML CAPE, up to 3000 J/Kg will be present with 30 to
maybe 40 knots of 0-3 km shear. The large hail threat may become
more limited into the late evening and overnight as the heavy rain
threat becomes more of an issue.
The rain should end early Wednesday morning as the complex moves
off to the east. This could leave most of the area dry for a good
share of the day, but this is an area where the models have
changed their solutions recently. The main upper level trough
hangs back to the northwest of the area as it forms into an upper
level low across southern Manitoba and Ontario. There are now
indications that this will help draw another short wave trough out
of the central Rockies and move it across the region Wednesday
night. This wave looks to ride along the front, which the models
do not push all the far south with the complex of storms tonight.
The 11.12Z GFS and ECMWF are the most similar taking the front
down to the Iowa/Missouri border while the 11.12Z NAM only pushes
it to about Interstate 80. The moisture transport will be focused
on the front again Wednesday night, but it does not look to be as
strong as tonight, and will help form another complex of storms
along and north of the front. With the farther north solution, the
NAM would bring the potential for another round of heavy rains
across the southern parts of the area while the GFS and ECMWF keep
it south of the forecast area. For now, will go with the more
southern solutions but the position of the front will have to be
closely monitored Wednesday.
.LONG TERM...(Friday through Tuesday)
Issued at 213 PM CDT Tue Jul 11 2017
Much of this period looks to be dry as the upper level ridge
builds over the western United States. The Upper Midwest looks to
be on the edge of the westerlies as they top the ridge axis with
some suggestion by the models that a short wave trough could move
across the Great Lakes over the weekend. Based on this, plan to
include some small rain chances across the northeast Saturday
afternoon and night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 638 PM CDT Tue Jul 11 2017
Watching multiple clusters of thunderstorms across the eastern
Dakotas early this evening. These storms are expected to move
across MN in some form later this evening and into portions of the
Upper MS River Valley mainly overnight. The consistency in track
and evolution of these storms from model run to model run has been
rather poor, so will keep with the idea of VCTS at both TAF
airfields starting at 12.05Z and ending at 12.10Z. Will also keep
VFR conditions at this time, but if thunderstorms do in fact
impact KRST or KLSE, will need to amend for likely lower MVFR/
brief IFR conditions. For the rest of Wednesday, look for mainly
dry VFR conditions. Winds away from thunderstorms will be light
from the south-southeast until eventually turning to the southwest
late in the period.
&&
.HYDROLOGY...
Issued at 213 PM CDT Tue Jul 11 2017
Flash flood watch issued early today to address the potential for
heavy rain falling on areas that were primed by the heavy rain
Sunday night. Once the convective complex develops this evening,
it should transition into a heavy rain maker. The low level
moisture transport will remained focused on the front and into the
area for a good share of the night. There does not look to be much
of a decrease in the CAPE downstream of the area, which will help
maintain a good feed of elevated instability into the complex.
Precipitable waters look to be in the 1.75 to 2 inch range with
warm cloud depths of 4 to 4.5 km. This will make the storms
efficient rain producers and any storm will have the potential for
produce locally heavy rains. Focused the flash flood watch over
the areas that received 1 to 3 inches of rain Sunday night and can
take the least amount of additional rains. The runoff from the
heavy rains will likely result in the some rises on area rivers as
well.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Flash Flood Watch from 10 PM CDT this evening through Wednesday
morning for WIZ033-034-041-042-053-055.
Flash Flood Watch from 10 PM CDT this evening through Wednesday
morning for WIZ043-044.
MN...None.
IA...None.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...Rogers
HYDROLOGY...04
Area Forecast Discussion
National Weather Service Bismarck ND
942 PM CDT Tue Jul 11 2017
.UPDATE...
Issued at 939 PM CDT Tue Jul 11 2017
Continuing to monitor two strong to severe storms across eastern
Montana as of 0230 UTC. However, with sunset these storms may not
make it to the North Dakota border, or be significantly weaker if
they do. Otherwise, stratus has begun to enter northern North
Dakota, and will overtake most of the area through the night.
UPDATE Issued at 537 PM CDT Tue Jul 11 2017
Continuing to monitor two areas of potential convective initiation.
The first across far south central North Dakota and into the
James River Valley highlighted by an agitated cumulus/tower
cumulus field, and the second across north central North Dakota
where deeper moisture resides. Through 2230 UTC, each has shown a
few attempts at initiating convection, however, nothing has been
able to sustain itself as of yet. The north central has the best
potential for severe convection ahead of the upper level trough
with surface dewpoints in the 60s, MLCAPE between 1500-2500 j/kg
and effective deep layer shear around 30kts. CAMs through the 20
UTC HRRR have hinted at initiation further west of ongoing
convection across eastern North Dakota, and later in the evening
past 00 UTC. However, this remains rather uncertain given the
lack of sustained convection thus far with this setup.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 134 PM CDT Tue Jul 11 2017
Afternoon and evening thunderstorms are the main concern, followed
by Aviation concerns tonight and Wednesday.
Current surface analysis indicates low pressure located over far
southwest Manitoba with a warm front extending southward through
eastern ND and a cold front pushing through western and into
central ND. A re-enforcing cold front is also extending west
through southern Saskatchewan, with considerable clouds along and
just ahead of this boundary. The latest satellite analysis shows a
few subtle shortwaves, one currently tracking east across north
central ND, another moving through east central MT and a third
over southwest/south central Saskatchewan.
Latest RAP forecast soundings indicate mainly moderate CAPE around
1500 J/KG with bulk shear around 30 kts. The instability lingers
through around 5 PM before rapidly diminishing as we head into the
evening. The problem here is that there is still a small cap
remaining, with an unfavorable wind profile in the lower
atmosphere, until you get farther north into Manitoba. With that
said, there is a small potential for a strong to severe storm this
afternoon into early evening along the Canadian border.
As you get farther south the amount of instability available
decreases. Directional shear is not great but bulk shear remains
at 30 to 40 knots. Downdraft cape is increasing over western North
Dakota. Recently convection has developed in the far northwest ND
and northeast MT. Hail CAPE remains impressive from around
Williston and north, but decreases rapidly as you get south of the
Missouri, so the main threat for any convection in southwest ND
would be gusty winds. And the farther south you go, across
southwest and south central ND, the instability becomes quite
meager, especially as you get south of the I-94 corridor.
In the far southeast CWA we are very unstable through around 3-4
PM with RAP forecast sounding at Oakes indicating over 2500 J/KG
of CAPE and nearly 40 knots of shear. However, weak capping
remains. The majority of CAMS indicate convection firing more to
the east of the southern JRV. Will have to monitor though as if
anything would develop, the potential for rapidly developing
severe convection would exist. After 4 pm the CAPE begins to
diminish quickly, with the passage of the cold front.
Later tonight attention turns to Aviation as widespread MVFR to
IFR ceilings behind the aforementioned cold front, drops south
over North Dakota. Will leave details to the Aviation forecast.
but the increased clouds and cooler temperatures will mean a much
cooler day on Wednesday with is will set the stage for a much
cooler temperature forecast on Wednesday with highs possibly not
getting out of the 60s across the north.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 134 PM CDT Tue Jul 11 2017
Hot and dry weather will be the focus of the long term forecast.
After a cool night Wednesday night, high pressure aloft, sitting
over the CONUS southwest, amplifies and yields another warming
trend Thursday through Monday. High temperatures generally in the
mid to upper 90s but a few readings to around 105 may be possible
Friday and around 100 in the west Sunday and the west and south
Monday.
No big precipitation events advertised but embedded impulses will
trigger the occasional afternoon or nighttime thunderstorm.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 939 PM CDT Tue Jul 11 2017
An isolated thunderstorm is possible across far southwest North
Dakota this evening. MVFR/IFR stratus is expected to build from
north to south tonight into Wednesday morning across western and
central North Dakota.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PA
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...PA
Area Forecast Discussion
National Weather Service Denver/Boulder CO
846 PM MDT Tue Jul 11 2017
.UPDATE...
Issued at 845 PM MDT Tue Jul 11 2017
Only minor updates were made to tonights forecast. Convection in
general has been weak and widely scattered. Latest radar and
lightning trends indicate no lightning and weakening showers,
especially as they leave the higher terrain and encounter the very
dry low- level air across the I-25 corridor. The exception is
across southern Lincoln county where a narrow ribbon of
instability with MLCAPE in the 600-800 J/kg range exists.
Thunderstorms with gusty winds to 40 mph and brief heavy rain will
continue for an hour or so before weakening/moving east. Thus the
main update for tonight was to remove mention of thunder all
areas other than southern Lincoln County.
High res model data continue to indicate showers continuing mainly
over the high country tonight. This would be great for fire
weather conditions. GOES-16 Water Vapor loops show mid and high
level moisture streaming into the state from the southwest.
Upstream convection is not impressive but looks robust enough to
keep the PoPs up in the mountains tonight for a chance of light
rain showers. With very dry air east of the Rockies at the low
levels, even the HRRR is having a hard time keeping the showers
going as they move east across the I-25 corridor with the latest
runs. Existing low PoPs look good through midnight tonight below
6000 feet elevation.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 349 PM MDT Tue Jul 11 2017
Convective coverage has been quite limited thus far. Some of this
appears to be due to a cirrus shield that passed across the Front
Range during max heating, but more likely due to drying as latest
Integrated Precipitable Water from GPS has dropped 0.10 to 0.20
during the last few hours. Hard to say exactly where this drying
came from, but the real data shows odds of much rain are
decreasing. There is one favorable mechanism yet, and that is the
passing upper level speed max to our north. We will get into the
right entrance region of the upper jet later this evening, which
could help convective coverage. We will still focus the higher
PoPs over the higher terrain.
For Wednesday, the plume of mid level moisture will remain over
the area as evidenced in the 700-500 mb specific humidity charts.
There will be weak instability with surface based CAPES of a few
hundred J/kg. LCLs drop a little, but are still relatively high
near 14-15 thousand feet MSL. Gusty outflow winds can again be
expected with storms, and storms should be capable of producing
more rainfall with a bit more precipitable water (PW). Models
have been consistently over predicting PW so will have to watch
the latest real data to see if this ever materializes.
Temperatures should drop a few more degrees with slight cooling
and moistening aloft, finally close to normal levels for this time
of year.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 349 PM MDT Tue Jul 11 2017
Broad circulation around the upper high over KS/OK Wed night will
continue to stream mid and high-level subtropical moisture across
southern and eastern sections of CO through Thursday. Greatest
specific humidity and PW will be over e-central CO Wed night and
over sern CO on Thursday. In addition, areas east of the mtns will
remain exposed to a relatively moist low-level ely flow Wed night
keeping storm chances going over and along the Front Range
mountains/foothills. That includes the Palmer Divide. Model precip
amounts for the overnight period appear to be reasonable,
although models may be under playing the pockets of higher QPF
(0.40-0.75 inch) with those storms slowly tracking eastward across
South Park, the southern foothills and Palmer Divide during the
evening hours. Do not see all that much clearing overnight.
On Thursday...should see the weak disturbance in mid-level flow
exiting eastern portions of the fcst area during the morning,
taking with it the few lingering showers and lower cloud cover.
By afternoon, a shift to a sely bndry layer flow east of the mtns
appears to concentrate low-level moisture over sern sections of
the CWA, such as along the Palmer Divide. This is where storm
chances should be greatest on Thursday, as well as over the
southern foothills and South Park areas with this orographically
favorable sely flow. Temps on Thursday about the same if not a deg
or two lower than those on Wednesday in response to slight
cooling aloft.
Looking ahead, medium range models show a beastly hot upper ridge
building up once again over the Great Basin, with a 600 decameter
500mb high pres centered over Utah on Saturday. Broad clockwise
circulation around this upper high redirects the subtropical/monsoon
moisture plume westward away from Colorado during the weekend,
and possibly on Monday as well. Consequently, t-storm chances
around these parts should drop off considerably, although higher
elevations may still see their daily rounds of isolated to
scattered gusty storms during the afternoon and early evening
hours. Nwly flow aloft on the east side of the upper ridge will
keep temps around here near to slightly above their seasonal
averages.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 845 PM MDT Tue Jul 11 2017
VFR conditions expected through Wednesday. Strong outflow
continues across the TAF sites this evening, generally out of the
southwest direction. These winds should weaken by 05Z and then go
to drainage around 10 kts. Rain showers look to continue across
the higher elevations west of the TAF sites but do not expect any
rain at the TAF sites other than a sprinkle or two through 04Z,
and no chance of thunder. Rain chances are not high enough to
include in the TAFs. Thunderstorm chances with gusts around 30 kts
increase again tomorrow after 21Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Schlatter
SHORT TERM...Barjenbruch
LONG TERM...Baker
AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Des Moines IA
649 PM CDT Tue Jul 11 2017
.UPDATE...
Issued at 632 PM CDT Tue Jul 11 2017
Will be letting heat advisory expire at 8 pm this evening. Warm
and humid overnight. Dewpoint pooling over central Iowa along the
weak warm front is area of concern. Upstream convection now
beginning to develop in eastern South Dakota may take a turn
toward the boundary later this evening. Latest SPC HRRR
attempting to relocate convection overnight. H700 cap rather
strong at +13 to +14C over the west...so will have to weigh that
versus any upstream development. /rev
&&
.SHORT TERM.../Tonight through Wednesday/
Issued at 328 PM CDT Tue Jul 11 2017
Excessive heat has been the weather highlight so far today. Dew
points have run a few degrees higher than guidance this morning,
with many locations along and south of Highway 30 in the mid to
upper 70s and heat indices near or exceeding 105 degrees. Little
relief tonight as the oppressive humidity limits cooling to the mid
to upper 70s.
A weak shortwave passing through today has supported scattered
elevated showers and storms to the north of a slowly advancing warm
front. This activity should dissipate and move out of the CWA in the
next couple hours. Although the atmosphere is highly unstable, warm
temperatures aloft will likely keep a firm cap on convection until
late tonight. Hi-res models continue to advertise a line(s) of
storms diving south out of Minnesota after 5z, likely in the
vicinity of a warm front that will be draped from north central to
east central Iowa. These storms may be severe with large hail and
damaging winds given that they will be working with an environment
characterized by 2000+ J/kg of MUCAPE rooted above 850mb and 25-30
kts of effective shear. Additional storms are possible in parts of
central and southern Iowa overnight into early Wed morning as theta-
e advection ramps up in concert with a strengthening low level jet.
Confidence is low at this time due to warm temperatures aloft, but
storms didn`t have much difficulty firing last night in a similar
environment.
Heat will once again be an issue tomorrow as temperatures push back
into the 90s with high humidity. Another Heat Advisory has been
issued for parts of southwest Iowa where confidence is highest that
heat indicies will approach 105 degrees at times. The advisory may
be expanded further north and east similar to today, however at this
time the spatial extent of cloud cover and the impact on temps
remains in question. Next round of storms will be possible by late
afternoon as a stronger shortwave trough near the Canadian border
forces the aforementioned front back south into northeast
Nebraska/northwest Iowa. Weak cold air advection in the 850-700mb
layer will weaken the cap in the vicinity of the front and support
the development of isolated to scattered strong to severe storms.
.LONG TERM.../Wednesday night through Tuesday/
Issued at 328 PM CDT Tue Jul 11 2017
Front will move south through Iowa on Wednesday night with ongoing
convection at the beginning of the period. The convection will be
fed by strong instability south of the boundary and with strong
westerly flow aloft, sufficient shear for some organization into
strong to severe storms. This activity will sink southeast across
the state during the night as the front settles toward Missouri.
Much of the convection will have ended by Thursday morning as the
front slides south of Iowa and drier air pushes into the state.
This cooler and drier airmass will linger from Thursday into
Friday with Iowa on southern periphery of Canadian high pressure
sliding through Minnesota and Wisconsin.
After this period, attention turns to building ridge across the
intermountain west. Thermally, readings will warm underneath this
ridge and slide east toward the region into the weekend with
gradual warming. However, both GFS and Euro do indicate a boundary
sliding through Iowa on Sunday which will put a hold on the warm
briefly. However, the upper ridge is expected to slide east into
the central United States by the middle of next week with a large
area of much above normal temperatures into the Plains edging into
Iowa. Euro remains somewhat flatter in the amplitude while GFS is
more pronounced in the northern extent of the ridge. Both would
indicate the hot and humid conditions returning with the Euro
holding the southern edge of the westerlies closer to Iowa. This
would suggest a better threat of a convective system dropping into
the state, but still somewhat limited. For now, much of the
forecast will be dry into next week with temperatures remaining
above normal.
&&
.AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/
Issued at 648 PM CDT Tue Jul 11 2017
Main concern overnight will be convective trends and wind shear.
Late evening wind shear expected to develop with low level jet.
Otherwise...continuing to monitor convective potential. Weakness
in cap has allowed severe convection to develop near KIOW/KCID in
eastern Iowa. Weak boundary sitting over central Iowa now...
upstream convection may propagate into instability axis after 05z.
Latest SPC HRRR shows that aft 06z through 12z...convection may
affect KFOD...KDSM...areas southeast aft 12z. Continuing VCTS for
now...Will monitor trends for more specifics in 06z TAF package.
/rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for IAZ057>060-070>075-
081>086-092>097.
Heat Advisory from noon to 7 PM CDT Wednesday for IAZ081>083-
092>094.
&&
$$
UPDATE...REV
SHORT TERM...Martin
LONG TERM...Cogil
AVIATION...REV
Area Forecast Discussion
National Weather Service Quad Cities IA IL
646 PM CDT Tue Jul 11 2017
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 328 PM CDT Tue Jul 11 2017
18Z surface data has a stationary front running from the south shore
of Lake Michigan into northern Iowa and then into southwest
Minnesota. Dew points were in the 70s south of the front with 60s
north of the front.
&&
.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 328 PM CDT Tue Jul 11 2017
There are several concerns over the next 36 hours. These concerns
are heavy rain risk, severe risk, and heat.
Based on the 18z sounding, the atmosphere looks capped through
sunset south of the front. The exception is the far north where some
showers and possibly a few thunderstorms will be seen. The heat
advisory will continue until 8 PM.
Heavy rain concern. The question tonight becomes where and where
does the organized thunderstorm complex develop. The 850 and 700 mb
temperatures increasing across the area tonight which could push the
organized convection further north. However, the cloud band across
Iowa is troubling in that the effective boundary appears to be
further south than what the models suggest.
If the effective boundary is further south, then the organized
thunderstorm complex would be over the area instead of Wisconsin.
Trends with the RAP do show the backward/forward Corfidi vectors
becoming perpendicular and then opposing each other prior to sunrise
across the area. Convergence aloft then shifts to the south over the
area prior to sunrise Wednesday.
Thus the scenario that is being suggested is a heavy rain event for
the area. Given the high PWATs feeding into the area and a potential
for storms to move repeatedly across the same area, flash flooding
would be a concern.
Unfortunately, the overall situation becomes a met watch. Once
individual storms begin developing this evening, the overall risk
area will become known and changes to the forecast can be made.
So, the forecast as of now has little if any rain during the evening
hours except in the highway 20 corridor. After midnight, slight
chance to chance pops across the northern half of the area.
Severe concern. Given the energy potential built up into the
atmosphere, individual storms could be severe tonight before growing
upscale into a heavy rain thunderstorm complex.
Heat concern. Depending upon how the nocturnal convection
develops/evolves tonight will dictate how hot it will get on
Wednesday. IF an organized thunderstorm complex occurs tonight that
develops a strong pool of cool air, then although very humid on
Wednesday, temperatures would likely remain in the 80s. If no
organized thunderstorm complex occurs across the area tonight, then
temperatures will get into the 90s Wednesday with heat index
readings over 100.
.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 328 PM CDT Tue Jul 11 2017
Active period of weather to continue through the beginning of the
long term period. Later in the week, weather should begin to calm
and temperatures should be lower, before a ridge moves into the area
for later in the week and the return to warm weather occurs.
Wednesday night, convection will either likely be ongoing at 00z or
shortly there after as a cold front is moving south through the
area. The coverage of storms will likely be greatest in the 03z -
09z time frame as they slowly drift south. The question of storm
severity is based on two unknowns at this time. 1.) Overnight
convection tonight and into tomorrow and 2.) What that could leave
us. The possibility of overnight convection across our area could
change the position of boundaries for tomorrow. Also MCV
development could further complicate the forecast. Overall shear is
weak until a weak H5 wave will move into the area overnight
Wednesday. Whether or not this wave leads to increased severe
weather is at question due to the timing of the convection. The
best threat for severe weather would be if a MCV were to be across
the area during the day on Wednesday, increasing overall shear for
the evening convection. Currently think, hydro issues may be the
main threat. The slow moving nature of the system, along with
corfidi vectors favoring training of thunderstorms, PWATs that are
in excess of 2 inches, and a H85 jet that is parallel to the storms,
flash flooding could become a larger threat than any severe weather.
Flash flood watches may be needed later, especially once tonights
convection is resolved.
After this, the flow turns more northerly as drier air moves into
the area for this weekend. A wave in this flow will cause more
moist air to return for Saturday before drier air moves in once
again. Temperatures should be cooler than earlier this week, before
the warm dome creeps back in next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
ISSUED AT 640 PM CDT Tue Jul 11 2017
VFR conditions with isolated shra/tsra will continue through
03z/12. After 03z/12 spotty MVFR conditions are possible due to
the high moisture levels in the lower atmosphere. A nocturnal
convective complex will develop but questions remain as to where.
One possible scenario is across Wisconsin that may affect KDBQ.
Another scenario is in central Iowa that moves east that may
affect several TAF sites. If a TSRA affects a TAF site, a period
of IFR conditions is very possible.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory until 8 PM CDT this evening for Des Moines-Henry
IA-Jefferson-Keokuk-Lee-Louisa-Van Buren-Washington.
IL...Heat Advisory until 8 PM CDT this evening for Hancock-Henderson-
McDonough-Mercer-Warren.
MO...Heat Advisory until 8 PM CDT this evening for Clark-Scotland.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...Gibbs
AVIATION...08
Area Forecast Discussion
National Weather Service Green Bay WI
956 PM CDT Tue Jul 11 2017
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Wednesday
Issued at 239 PM CDT Tue Jul 11 2017
A warm afternoon was noted across the region with temperatures
in the 80s away from the bay and lake. Heat index values were
approaching 90 in a few spots.
A weak upper level disturbance moving across the western Great
Lakes this afternoon and early this evening may kick off a few
thunderstorms across east-central Wisconsin. Another disturbance
moving north of the state will also bring a chance of showers and
thunderstorms to portions of far northeast Wisconsin for the
remainder of the afternoon through the mid evening hours. 0-6km
shear values around 30 knots, thus could not rule out an isolated
pulse severe storm.
Attention then turns to the main show later tonight. A complex of
thunderstorms is expected to develop west of the area later this
evening and then dive southeast into the region around midnight
across central Wisconsin and into northeast Wisconsin towards
sunrise. Have trended pop grids in accordance with the latest
HRRR run which has the complex moving across central Wisconsin
between midnight and 4 am and across the Fox Valley and lakeshore
region between 4 am and 8 am. Damaging winds are the primary
concern although some discrete cells could have some hail with
them despite high wet bulb zero heights.
Many question arise after the storms pass later Wednesday morning
and afternoon. The latest bufkit soundings of the NAM would
suggest the area will be capped and storms would form until
Wednesday evening until upper support arrives. Per coordination
with surrounding offices, have a small chance of storms Wednesday
afternoon. If storms do form, they would probably become strong or
severe. Leaned toward the warmer MAV guidance for highs on
Wednesday.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 239 PM CDT Tue Jul 11 2017
Although the main cold front will be south of the area by
Wednesday night, there will be lingering instability across the
region during the evening hours, particularly across the southern
cwa. Although instability steadily declines through the overnight
hours, MUCAPEs are still a respectable 1500 to 3000 J/kg during
the evening hours with bulk shear values of 40 to 50 knots. A
shortwave tracking through the western Great Lakes may be the
necessary trigger for convection during the evening hours. Many of
the meso models like the HRRRX, ARW and NMM fire up convection
during the evening hours across central and east-central Wisconsin
with this feature. If thunderstorms form during this period they
could be strong to severe given the instability and shear. Model
soundings indicate the main threat will primarily be damaging
winds and heavy rainfall as PWATs approach 1.75 inches, with large
hail a possibility but less of a threat given fairly high wet-bulb
heights of 12-13k ft.
Once this low sinks further south POPs will be even lower on
Thursday, however there is a chance for showers across the
northern cwa as a mid-level trough tracks through the northern
Great Lakes region. High pressure will then build in across the
western Great Lakes region providing dry weather for the end of
the work week.
A cold front sinking south Saturday and Saturday night will bring
the next chance for showers and thunderstorms to the region. Early
indications are there will be quite a bit of instability Saturday
afternoon and evening, with MUCAPEs ranging from 2000 J/kg across
the north, with 3000 to 4000 J/kg across the southern cwa. The
main fly in the ointment appears to be a fairly strong cap in
place, however any storms that can form could be strong to severe
given the amount of instability across the region.
Chances for showers and thunderstorms persist into Wednesday
evening with a departing surface low. Only low end chance PoPs
and slight chances remain for the rest of the night into Thursday
as a mid level trough axis passes through Wisconsin. Highest PoPs
are along the Upper Michigan border, closer to the stronger upper
support. Surface high pressure moving into the Great Lakes should
help to keep things mostly dry Friday and Friday night. The 00Z
GFS, ECMWF and Canadian models all had a cold front moving
through northern Wisconsin Saturday or Saturday night, but there
were timing differences so there are low PoPs on Saturday and
Saturday night as a result. The next surface high and central
CONUS ridge will keep things dry the rest of the weekend into the
early part of the new work week. The ridge then starts to break
down and a warm front approaches the area so there is a chance
for showers and storms across part of north central Wisconsin
Monday afternoon.
High pressure builds in for the second half of the weekend,
bringing dry weather to northeast Wisconsin through early next
week as large scale ridging builds in across the western Great
Lakes.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 955 PM CDT Tue Jul 11 2017
VFR conditions are expected for the duration of the late evening
and early morning hours. A thunderstorm complex is expected to
form over Minnesota late tonight and move across the region late
tonight and early Wednesday. The strongest storms should be over
central Wisconsin, with the lowest ceilings and visibilities
across the north. The activity should exit by 15z Wednesday with
mostly VFR flight conditions and scattered showers or
thunderstorms afterwards. &&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....Eckberg
LONG TERM......Kurimski
AVIATION.......RDM
Area Forecast Discussion
National Weather Service Indianapolis IN
1148 PM EDT Tue Jul 11 2017
.UPDATE...
Aviation sections have been updated below.
&&
.SYNOPSIS...
Issued at 246 PM EDT Tue Jul 11 2017
A brief break from thunderstorms can be expected Wednesday, before
rain chances return by Thursday with a cold front. High pressure
will then provide dry conditions Saturday. A couple of fronts could
bring some more rain to parts of the area Sunday and Tuesday. Hot
and humid conditions midweek will give way to closer to average
conditions by the weekend.
&&
.NEAR TERM.../Rest of Tonight/
Issued at 1030 PM EDT Tue Jul 11 2017
Thunderstorms have redeveloped over extreme northern Illinois...
but these should stay well north of our region. Radar indicated
a few light echoes across our far north. Main change with this
update is to drop mention of thunder rest of tonight and to keep
a slight chance of showers far north to about 09Z.
Low temperatures near 70 still seems on track given dewpoints near
70 and some wind and warm advection overnight.
&&
.SHORT TERM.../Wednesday through Friday/
Issued at 246 PM EDT Tue Jul 11 2017
Models are close enough that the model blend initialization
was accepted for most items.
On Wednesday the upper ridge nudges into the area and temperatures
aloft warm. This should inhibit convection for the much of the area.
Cannot rule out an isolated storm, but odds are too low to mention.
Went cooler than most guidance for highs across a good part of the
area with the wet ground. It will still be very warm though with
highs in the upper 80s to around 90.
Wednesday night a cold front will approach the area, so will go with
some chance PoPs across the northwest half or so of the forecast
area. As the front moves into the area Thursday and Thursday night
will go chance PoPs all areas. Will keep some lingering PoPs Friday
as the front exits.
Wouldn`t rule out some strong storms on Thursday with the front.
Confidence is medium in chances and timing of rain during the short
term as how convection develops one period could affect the next
period`s chances.
&&
.LONG TERM /Friday night through Monday/...
Issued at 212 PM EDT Tue Jul 11 2017
Central Indiana is expected to dry out this weekend and early next
week as ensembles expand the Rockies upper ridge to the northeast.
This will help let river and stream crests progress as quickly as
possible. Confidence in mostly dry weather is good.
See not reason to mess with seasonable blend temperatures with highs
mostly in the 80s.
&&
.AVIATION /Discussion for the 120600Z TAF Issuance/...
Issued at 1148 PM EDT Tue Jul 11 2017
Brief period of MVFR possible at KIND and KLAF TAF`s overnight.
Otherwise...VFR.
Areas of fog with patchy stratus have developed at a few sites from
INDY and northward. RAP and NAM models show some low level drying
overnight as southwest flow increases. Even if sites go MVFR...I
have low confidence that it would continue overnight.
High pressure off the southeast coast and low pressure moving
into the upper midwest will keep us under a moderate southwest flow.
Models hint at marginal low level wind shear at KLAF overnight.
Winds will be southwest 5 to 8 knots overnight and southwest up to
12 knots on Wednesday. Could see few CU most areas Wednesday
afternoon and north portions Wednesday night. Otherwise only thin
high clouds expected most areas.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...JH
SHORT TERM...50
LONG TERM...MK
AVIATION...JH
Area Forecast Discussion
National Weather Service Jacksonville FL
833 PM EDT Tue Jul 11 2017
.UPDATE..Convection gradually dissipating across interior ne
FL...while still ongoing interior se GA. Expect GA activity
to gradually diminish thru Midnight as suggested by the HRRR
model...then partly cloudy skies. Current low temp forecast
looks good...with lwr-mid 70s.
&&
.AVIATION...VFR conditions expected next 24 hours...with locally
lower conditions with widely scattered afternoon TSRA...but very
low coverage leads me to keep TS out of the TAFs for Wed
afternoon.
&&
.MARINE...Surface ridge will shift north which will set up an
easterly flow through this week. Winds will be less than 15 knots
with seas mostly in the 2 to 4 foot range.
Rip Currents: Low risk becoming moderate on Wednesday as onshore
winds increase.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 73 93 73 95 / 50 30 10 10
SSI 76 88 78 88 / 10 10 10 10
JAX 73 91 75 91 / 10 10 10 20
SGJ 73 88 77 88 / 10 20 10 30
GNV 72 93 73 92 / 20 30 10 30
OCF 71 92 74 91 / 30 30 10 30
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Wolf/Elsenheimer/Peterson
Area Forecast Discussion
National Weather Service Louisville KY
903 PM EDT Tue Jul 11 2017
.Forecast Update...
Issued at 0850 PM EDT Tue Jul 11 2017
The current forecast looks to be on track. Precipitation moved off
to the northeast. Skies will continue to clear overnight.
&&
.Short Term...(This evening through Wednesday night)
Issued at 230 PM EDT Tue Jul 11 2017
Several rounds of storms have tracked across central Indiana into
portions of western and southwest Ohio today, producing upwards of 4-
6 inches of rain in many places. Further south across southern
Indiana and central Kentucky, mainly dry conditions have prevailed
outside of one storm that clipped portions of Jefferson County, IN.
Convective debris clouds have spilled over the northern half of the
forecast area today, keeping temperatures down in the 80s, while
across south-central Kentucky mostly sunny skies prevailed.
Overall, the near term forecast challenge is whether any storms will
brush parts of southern Indiana through the remainder of the
afternoon. Current complex should stay just north of the area, then
overall threat will decrease as main focus shifts back to the
northwest where convection initiation is expected. Overall, HRRR and
other hi-res models in good agreement in a mainly dry forecast
through this evening. It will remain quite mild and muggy overnight
with mix of high clouds and southerly winds. Plan on lows in the
lower to middle 70s.
For Wednesday, low pressure tracking across the lower Great Lakes
will allow stronger southwesterly flow to setup across Kentucky and
southern Indiana. It should be the warmest day of the week and one
of the warmer days of the summer so far with highs in the upper 80s
to lower 90s. The urban centers may reach 93-94 though recent
rainfall and lush vegetation may limit highs somewhat. Nonetheless,
with dewpoints around 70, maximum afternoon heat indices will top
out in the 95 to 100 range. Very mild conditions are expected
Wednesday night with readings slow to fall and only dipping down
into the lower 70s.
.Long Term...(Thursday through Tuesday)
Issued at 235 PM EDT Tue Jul 11 2017
Low pressure tracking across the Great Lakes Thursday into Friday
will slowly drag a cold front across the area Thursday night into
Friday. Ahead of that front, isolated thunderstorms will be possible
during the daytime associated with maximum heating in a weakly
capped environment. Better chances will come with the frontal
passage Thursday night and Friday. Some of the storms may be on the
strong side during this period with heavy rainfall, gusty winds, and
frequent lightning being the main threats. Highs during the period
will be in the mid-upper 80s with overnight lows in the upper 60s to
lower 70s.
Drier and cooler conditions look to return by Saturday and into
Sunday as the pattern reverts back to a ridge west, trough east type
pattern. With the trough to our east, we`ll remain in a general
northwesterly flow aloft. Daily highs will range from the mid-upper
80s with overnight lows in the middle 60s.
Going into next week, the 11.12z deterministic and ensemble data
shows troughing early on Monday but then upper level ridging
attempting to build across the central Plains and eastward into the
lower Ohio Valley. If this materializes, then more summer heat
and humidity could spread across the area.
&&
.Aviation...(00Z TAF Issuance)
Issued at 626 PM EDT Tue Jul 11 2017
VFR conditions expected through the period. Weak southerly to
southwesterly winds tonight will pick up again tomorrow afternoon as
boundary layer mixing occurs. Some gusts could approach 15kts.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...KDW
Short Term...ZT
Long Term...ZT
Aviation...DM
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
858 PM CDT Tue Jul 11 2017
.UPDATE...
858 PM CDT
Evening Update...
Some adjustments to going forecast this evening primarily to
tighten up gradient in pops with focus mainly across far north and
northeast IL, and also bumped overnight mins, Wednesday maxes and
dew point temps a bit.
Surface analysis depicts warm front/old outflow boundary from
central Iowa into central IL this evening. Wind fields are fairly
light as would be expected this time of year however, with an
overall lack of strong convergence along this boundary leading
only to some isolated convection west of the Quad Cities late this
afternoon. It appears the better focus for convection overnight
will focus along the elevated baroclinic zone further north, where
new convection has developed over the past 1-2 hours over
northeastern IA. Convection allowing models (CAMs) are not doing
real well with this activity overall, though the 23-00Z RAP runs
seem to best capture the location of the northeastern IA storms,
and have generally based overnight convective trends on its
depiction, which develops storms northeast into southern WI and
far northern IL, and eventually east-southeast across the lake.
This would mainly affect northern tier of counties and the
northern Chicago suburbs into the early morning hours, so have
generally tightened up the pop gradient depicted in our hourly
gridded forecast to go drier south/central portions of the cwa,
with a tighter gradient to higher pops along the IL/WI border
area. Steep mid-level lapse rates and 40-45 kt effective bulk
shear would support well-organized updrafts which could present a
hail threat from the strongest cores, though the greater concern
will likely be the potential for locally heavy rainfall given the
west/northwest to east/southeast orientation line of storms and
potential for training within near 2" pwat atmosphere. Should be
some northeastward drift of the elevated warm front overnight so
threat may be more of a southern WI issue.
Surface obs since this afternoon indicate pool of high dew point
air across the region, generally in the low-mid 70`s, though with
upper 70`s just upstream along the surface warm front. With moist
low levels, south winds, and mid-high clouds from convection to
our west/northwest, expect overnight temps will be slow to cool
and have raised a category in most areas to mid-70`s. Wednesday
appears to have the potential to be fairly hot and humid, with
model 925 mb temps +26/27C. This would likely support highs in the
mid-90`s in some spots, though morning convective and outflow
issues decrease confidence a bit. Did warm Wednesday max temps and
dew points a little more solidly into the 93-ish range, which also
yields some heat index readings tagging 105. Would prefer to defer
to mid-shift for any potential heat advisory headline however,
given uncertain somewhat MCS trends at this time.
Ratzer
&&
.SHORT TERM...
243 PM CDT
Through Wednesday...
Main forecast concerns/challenges are with shower and
thunderstorm chances this afternoon through this evening, and
possible lingering thunderstorms Wednesday morning with hot/humid
conditions still expected.
In the near term, upstream shortwave energy continuing to
progress overhead and can be noted with additional thicker cloud
cover and weak returns beginning to show up on latest radar
imagery. At this time, thunder is not being observed and think
this will likely continue over the next 1-2 hours as large scale
ascent is weaker along with weaker surface focus. However, forcing
will increase slightly and latest RAP analysis is depicting
weakening CIN within this instability axis across far northern
Illinois. This could support isolated thunder in this area later
this afternoon but with forcing to remain weak and lapse rates
weak, any development should remain weak as well. Whatever
develops will exit by late afternoon/early evening, with a dry
period then likely.
Turn attention toward additional thunderstorm chances by mid to
late evening mainly across northern Illinois, with the highest
chances along/north of I-88. Guidance is struggling with
convective trends later this evening into the overnight hours.
Have continued the trend from the previous forecast though, with
scattered thunderstorm development possible along lifting surface
boundary later this evening into tonight. Increasing LLJ will help
support development along this boundary by mid/late evening,
primary along and north of I-88. Although a general easterly
movement will be in place, additional development through the
night will shift further to the north. So at this time, don`t
anticipate thunderstorm development all night. Will need to
continue monitoring overall trends this afternoon into the
evening, as a couple of other scenarios could occur. One scenario
is that the additional development late this evening could develop
just to the north, and then stay to the north through the night.
Another scenario would be for thunderstorms to develop along this
boundary later this evening, and then possibly train over portions
of northern Illinois. Once again, more probable solution would be
for scattered thunderstorms to develop over northern this
evening, and then shift north with time. Given the elevated
instability in place, there would be a severe wind and hail threat
with any storm. Heavy rainfall and localized flooding will also
continue to be concerns.
Have likely pops over far northern Illinois this evening, then
lower then to chance pops through the overnight hours. However, do
keep chance pops on Wednesday morning as its possible that
remnant MCS could clip the area. With possible cloud cover and
precip in the morning, high temps could be highly variable. At
this time, have maintained current forecast of highs around 90 as
it wouldn`t take much for conditions to quickly heat up. High
dewpoint axis looks to still be in place and support heat indices
of 100-105.
Rodriguez
&&
.LONG TERM...
209 PM CDT
Wednesday night through Tuesday...
Initial focus is on stormy conditions to begin the period. The
shortwave trough axis across the upper Midwest Wednesday will
shift east toward Lake Superior in the evening, with a belt of
stronger mid level flow and low amplitude shortwaves on the
southern fringe of this stronger wind field. Earlier development
across IA/MN will be driven by convergence on a cold front ahead
of these waves. Steering flow would suggest that this activity
would advect east across northern Illinois in the evening and
overnight hours, possibly in the form of an MCS or complex of
thunderstorms. The main threat period appears to be overnight. The
MUCAPE and increasing shear do support the threat maintaining
itself across the area during this time, with damaging winds and
possibly hail the main severe threats, but depending on previous
days rain, a flooding threat would be a concern given the 2"+
PWATs and very muggy airmass in place. A portion of the cold
front will help to scour out some of the humidity and instability
on Thursday. Where the front sets up on Thursday, additional
storms may again fire along in in the afternoon, but at this point
the focus area would be our southern area or points farther
south.
The occasionally wet pattern and the westerly weak shortwave
train will finally end as upper level low pressure across southern
Canada will shift east across the northern Great Lakes Thursday
night. As this occurs, high pressure at the surface will build
south across the upper midwest. This will help to shunt existing
frontal boundaries south of the area. The last wave is Thursday
night, and therefore there may be some lingering precip well south
before midnight. High pressure over MN/IA early Friday will move
east over the Mississippi Valley.
The upper level pattern will amplify this weekend as the big heat
dome across the west will build while troughing heads to the
eastern United States. A shortwave trough emanating from the
Pacific will dive south in this pattern Saturday night. As this
occurs, surface high pressure will sink south and allow a cold
front to also move south across the lake late Saturday into early
Sunday. Many guidance sources are dry, but the GFS/GFS ensembles
do paint some showers and storms overnight into early Sunday,
before reigniting on the front south of the area Sunday afternoon.
It appears beyond that the upper ridge in the west will finally
make its way in our direction, making for dry conditions, and
depending on the degree the ridge builds may allow to really heat
things up again the temperature department.
KMD
&&
.AVIATION...
For the 00Z TAFs...
Secondary warm front will lift north this evening with some
potential for scattered TSRA development ahead of the boundary.
Confidence in location of any potential development and coverage
is low, so maintained the VCTS in the TAFs until it becomes
clearer when/where/how widespread any development will be. Should
see a break in TSRA chances overnight, though cluster of TSRA
expected to develop well to our northwest this evening with some
threat of that activity moving through tomorrow morning in a
weakening phase. Prior to this convective cluster developing and
organizing it is hard to justify more than a PROB30 at this time.
However, should a weakening cluster of SHRA/TSRA move through
tomorrow morning it could cause several hours of a wind shift to
northeast, which is not conveyed in the TAFs as the more likely
scenario at this point is for increasingly gusty southwest winds.
- Izzi
&&
.MARINE...
209 PM CDT
There are no major periods of concern on Lake Michigan,
but winds will be varying a bit over the next few days. Gusty
northerly winds may build waves a little on the south half Sunday
into early Monday.
A stationary front on the southern tip of the lake
will shift north as a warm front tonight over a portion of Lake
Michigan before meandering back south later Thursday into Friday
as low pressure will spread from Iowa late today to Lake Huron by
early Friday. High pressure will build behind this low bringing a
brief period of northerly winds on Friday. The high will dip south
of the lake Saturday as another weak low will move east to
northern Lake Michigan Saturday, setting up a period of increased
southerly winds. This low will quickly move to the eastern Great
lakes by Sunday, as another high pressure area will shift to the
upper Great Lakes. Northerly winds return Sunday and Monday ahead
of the high that will sink south and spread over the lake late
Monday.
KMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
611 PM CDT Tue Jul 11 2017
.SHORT TERM... (Through Late Wednesday Afternoon)
Issued at 335 PM CDT Tue Jul 11 2017
Primary concern in the short term is the heat index forecast and
heat advisory for tomorrow. Warm southwest flow will continue
across the area tonight. Max temperatures across the area this
afternoon are in the mid to upper 90s...a couple of degrees warmer
than Monday`s highs in most areas. Expect temperatures tonight to
likewise be around this morning`s lows...perhaps a couple of degrees
warmer. It then follows that Wednesday`s highs will be near today`s
highs, if not a couple of degrees warmer in some places. This logic
is supported by 850mb temps in the 21-24C range and MOS guidance
temps in the mid 90s across the area. Guidance is showing dewpoint
temperatures ranging from around 68 to 72. The highest dewpoint
temperatures on Wednesday will likely be across northeast Missouri
into west central Illinois. This looks to produce heat index values
topping out around 105 Wednesday afternoon again. Will therefore
extend the current advisory up there through tomorrow. St. Louis
Metro advisory will also stay in place for heat index values of 100-
104 for 4 days.
In addition to the heat, introduced some slight chance PoPs over the
eastern Ozarks Wednesday afternoon. ESRL HRRR and NSSL WRF show
isolated convection down there during the late afternoon...and the
GFS and NAM are also spitting out some QPF. 15-20 PoPs look
reasonable.
Carney
.LONG TERM... (Wednesday Night through Next Tuesday)
Issued at 335 PM CDT Tue Jul 11 2017
A series of weak low amplitude disturbances will track from the
north central Plains into the lower Great Lakes region from
Wednesday night into early Thursday. This will allow an east-west
cold front to finally begin sagging south into northern MO and
northern IL by early Thursday morning. The NAM and ECWMF are a bit
faster with the frontal progress than the GFS and generally
preferred throughout the forecast period. Attendant with the more
southward position of the front will be a chance of showers and
thunderstorms during the overnight period.
There remains uncertainty with convective trends and impacts on
temperatures for Thursday. In general, thoughts are that any
existing morning convection should weaken by late morning. Then
there will be a big upswing in the afternoon as new convection
develops along the front as it moves southward and interacts with a
very unstable air mass. Multicell clusters and/or lines are expected
to evolve in light of the weak deep layer shear. The thunderstorm
threat will move southward in tandem with the front Thursday night
through Friday. There is still potential that the current heat
advisory for metro St. Louis may need to be extended into Thursday,
and possibly other areas along I-70 may qualify for a duration event
by this time pending the heat indices hit 100+. Given the
aforementioned uncertainty in convective trends and clouds, I have
held off on additional heat headlines for now.
Large scale amplification of the upper flow with a strong ridge in
the west and trof centered through eastern NOAM will keep the region
in northwest flow. Weak high pressure will dominate Saturday with a
reinforcing cold front and high pressure Sunday night into Monday.
Temperatures in this time frame look seasonable with lower dew
points and humidity. However, the western upper ridge/high looks to
build into the central U.S. by the middle of next week and take
residence bringing a return to big time heat.
Glass
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 540 PM CDT Tue Jul 11 2017
Few diurnal cumulus clouds will dissipate early this evening due
to the loss of daytime heating with only some high level clouds
expected later tonight into Wednesday morning. Few-scattered
diurnal cumulus clouds will develop again late Wednesday morning
and afternoon. The convection should remain north of the taf
sites. A south-southwesterly surface wind can be expected tonight,
then southwesterly on Wednesday, gusty at times late Wednesday
morning and afternoon.
SPECIFICS FOR KSTL: Few diurnal cumulus clouds will dissipate
early this evening due to the loss of daytime heating with only
some high level clouds expected later tonight into Wednesday
morning. Few-scattered diurnal cumulus clouds will develop again
late Wednesday morning and afternoon. The convection should remain
well north of the STL area. A south-southwesterly surface wind
can be expected tonight, then southwesterly on Wednesday, gusty at
times late Wednesday morning and afternoon.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory until 9 PM CDT Wednesday for Jefferson MO-Knox MO-
Lewis MO-Marion MO-Saint Charles MO-Saint Louis City MO-
Saint Louis MO-Shelby MO.
IL...Heat Advisory until 9 PM CDT Wednesday for Adams IL-Madison IL-
Monroe IL-Saint Clair IL.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1011 PM EDT Tue Jul 11 2017
.SYNOPSIS...
An offshore high and inland surface trough pattern will persist
through the week. A cold front will approach from the northwest
Saturday and then stall and dissipate Sunday into Tuesday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 1000 PM Tuesday...no changes with update. Latest HRRR
continues to indicate widely scattered shower/tstms for coast
overnight, thus no changes to slight chance POPs there late.
/Previous discussion/
As of 240 PM Tuesday...Ridge aloft just off the coast will lead
to weak zonal flow over region with no features to produce any
lift. Any remaining convection inland with sea breeze shld
dissipate quickly early this evening with generally dry weather
overnight with poss an isold shra/storm skirting the cst late.
Expect PC to mclr skies with muggy lows in the 70s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
As of 240 PM Tuesday...Ridge aloft just off the cst will cont
to lead to mainly dry weather over the region. Will cont isold
pop inland mainly during the aftn assoc with sea breeze but much
like today very few spots will see rain. With good deal of sun
expect highs in the lower 90s inland to 80s beaches.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
As of 240 pm Tue...Guidance remains in fairly good agreement
and continuity during period with zonal flow aloft most of the
week followed by troughing this weekend into early next week.
Thu...Models continue to show ridging/zonal flow for Wednesday
with surface trof temporarily pushed further to the west.
Forecast soundings and time sections show an overall drier
atmosphere and guidance PoPs are very low so have removed PoPs
and am going with a dry and hot day with highs in the lower/mid
90s inland with mid/upper 80s south coast and Outer Banks.
Fri thru Tue...An extended period of unsettled weather is in
store for the weekend into early next week. A persistent upper
level trof sets up across the eastern seaboard. At the surface,
a cold front will drift into the forecast area on Saturday and
becomes stationary into early next week. Numerous disturbances
moving through the upper flow on top of a warm, moist and
unstable airmass will result in chance PoPs each day through the
period. Still another very warm day Friday with highs expected
in the low to mid 90s inland to 85-90 coast and heat indices
around 100-103. A few degrees cooling expected over the weekend
into early next week with greater cloud/precip coverage with
highs upper 80s to around 90 inland to mid to upper 80s coast.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Short Term /thru 00Z Thursday/...
As of 730 PM Tuesday...VFR will dominate most of the period.
No convective activity expected to affect TAF sites through Wed
morning and then only isolated threat in afternoon. Light SW
winds expected to preclude fog threat again tonight but some
concern for repeat of IFR stratus development 09Z-12Z at inland
sites. Forecast soundings and additional aviation guidance do
not indicate widespread threat, thus will continue previous
forecast of only scattered deck at 800 feet that time period.
Scattered CU expected with heating during the day Wed with light
SW winds.
Long Term /Wed Night through Sun/
As of 240 pm Tue...VFR/dry weather forecast for Thursday. There
will periods of sub-VFR conditions in scattered
showers/thunderstorms Friday through Sunday as a cold front
moves into the area this weekend and becomes stationary. There
will also be occasional sub-VFR conditions during the early
morning hours with the threat for stratus and/or fog. Surface
winds southwest Thursday through Saturday and south Sunday.
Speeds will average 10-15 knots Thursday and Friday and 5-10
knots Saturday and around 5 knots Sunday.
&&
.MARINE...
Short Term /Tonight and Wed/...
As of 1000 PM Tuesday...no changes with update.
/Previous discussion/
As of 240 PM Tuesday...Light to moderate SW flow will cont with
high pres offshore and trof to the W. Speeds will be mainly in
the 10 to 20 kt range with winds peaking in the aftn to early
evening. These winds will cont to produce seas of 2 to 4 feet.
Long Term /Wednesday Night through Sunday/...
As of 240 pm Tuesday...Surface pattern will be dominated by an
offshore high and inland trough pattern through Friday with a
cold front moving in from the northwest Saturday and becoming
stationary across eastern NC. Flow will continue from the
southwest through the period at generally 5-15 knots. Seas will
average 2-5 feet.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...RF
NEAR TERM...RF/JBM
SHORT TERM...RF
LONG TERM...HSA
AVIATION...JBM/HSA
MARINE...RF/JBM/HSA
Area Forecast Discussion
National Weather Service Paducah KY
603 PM CDT Tue Jul 11 2017
.UPDATE...
Issued at 603 PM CDT Tue Jul 11 2017
Aviation update.
&&
.SHORT TERM...(Tonight through Thursday night)
Issued at 237 PM CDT Tue Jul 11 2017
The two main forecast concerns will be the heat Wednesday and
Thursday afternoon, and rain chances later on Thursday.
For the short term ingredients to generate heat index values, leaned
a little heavier toward the NAM-WRF family of guidance (12km NAM-
WRF, 4km NAM-WRF (NMM version), NAMnest, as well as the Canadian
guidance). In the very near term, included model weighting from the
HRRR and RAP guidance as well.
The heat index values may be underdone by 1-2 degrees over Southeast
Missouri and Southern Illinois. However, there is not a sufficient
coverage area to warrant a low end heat advisory at this time. Will
continue to highlight heat advisory values in Hazardous Weather
Outlook. Will also highlight in a Special Weather Statement or
Public Information Statement this afternoon, as well as in social
media.
Looking at the NAM-WRF/Canadian soundings, the thermal profile near
the edge of a sharp west to east oriented ridge axis over the WFO
PAH forecast area could be conducive for more robust showers and
thunderstorm activity during peak heating on Wednesday, but the lack
of deep layer moisture, marginal lapse rates at mid-levels, and weak
shear would make it difficult to maintain persistent updrafts for
any organized convection. There will be more cumulus development
from the south, and sporadic cumulus development along any
outflows from an MCS passage to the north of the WFO PAH forecast
area on Wednesday. If the forecast signal remains strong, a
mention of widely scattered showers and a few thunderstorms may be
warranted on Wednesday afternoon in the south.
Generally accepted the regionally blended model initialization for
rain chances on Thursday during peak heating, and any influence from
MCS to the north during the evening hours.
.LONG TERM...(Friday through Tuesday)
Issued at 237 PM CDT Tue Jul 11 2017
Above average confidence in much of the long term period as the
pattern transitions to a slightly cooler and less humid airmass
across the region.
The period will start with upper level ridging centered over the
Rocky Mountain region and shortwave energy diving southeast through
the Great Lakes. For the local area, model guidance continues to
show a weak cold front moving through on Friday, accompanied by some
showers and thunderstorms. The overall flow is weak with little in
the way of wind shear, thus not expecting any real organized
activity. The main concern will be localized heavy rain as
precipitable water is forecast to be around or slightly above 2
inches. Guidance has been trending toward drier conditions for
Friday night and Saturday morning. However, kept in some slight
chance PoPs in the south only in case it gets held up further north
for longer.
For the most part it looks like a nice weekend for mid summer, with
highs in the upper 80s and dewpoints down into the mid to upper 60s.
With upper level ridging center over the Northern Plains on Sunday,
shortwave energy is expected to shuttle down across the Upper
Midwest/Great Lakes region. Guidance disagrees on the strength and
exact placement. The 12z ECMWF is weaker and further northeast
keeping the region dry during this time. The 12z GFS and Canadian
are stronger and further southwest resulting in a weak cold front
moving in, accompanied by a chance of rain sometime in the Sunday
evening into Monday time frame. Will keep slight chance PoPs in for
now, given the uncertainty.
Dry conditions are expected Monday night into Tuesday as the upper
level ridge over the Plains begins to shift eastward. With winds not
expected to take on much of a southerly direction until mid week,
not expecting much in the way of a temperature or humidity increase
until then. Just outside of this forecast period, the upper ridge
may become centered closer to us, resulting in increasing
temperatures by mid to late next week.
&&
.AVIATION...
Issued at 603 PM CDT Tue Jul 11 2017
VFR conditions tonight through Wednesday. Light SSW winds tonight.
SSW winds up to 10 kts Wednesday, some gusts 15-20 kts possible.
Mix of high clouds. CU field expected by Wednesday afternoon.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
SHORT TERM...Smith
LONG TERM...SP
AVIATION....CN
Area Forecast Discussion
National Weather Service Phoenix AZ
825 PM MST Tue Jul 11 2017
.SYNOPSIS...
Near normal temperatures are expected through the week as high
pressure remains positioned over the Great Basin. Thunderstorms will
be possible over the higher terrain and parts of the lower deserts
of south-central and southwest Arizona each day. Areas of blowing
dust and strong winds will likely accompany any thunderstorms that
develop.
&&
.DISCUSSION...
Upper air data continued to show nearly excessive amounts of
atmospheric moisture strewn across central and southern AZ this
evening. Some entrance region jet dynamics/very weak short supported
widespread and tall convection over the Mogollon Rim this afternoon
and evening. Some Tstms topped out at 60 thsd ft msl.
An earlier concern involved a tight theta-e gradient between the
deserts vicinity Phoenix north to the Mogollon Rim, indicating the
possibility of back-building storms toward the lower deserts. This
did not occur as of 8 pm mst. Instead weak to moderately strong
convective outflows were moving south through the greater Phoenix
area at 8 pm mst, with a possibility of a thunderstorm in their
aftermath tonight.
The current slight chance of showers/thunderstorms will continue
tonight on the lower deserts west and south of Phoenix considering
atmospheric moisture levels are near excessive. Last evening a
gravity wave from eastern AZ initiated convection in the Phoenix
east valley, so anything is possible when moisture levels are high.
Current forecasts look ok. No short term updates planned.
.PREVIOUS DISCUSSION...
An extensive area of high and midlevel clouds are over the
eastern half of our CWA this afternoon which has limited surface
warming so far today. As of noon, temperatures are anywhere from
4-8 degrees cooler than they were at this time yesterday although
areas further west, like Blythe and El Centro, are nearly similar
under mostly sunny skies. Despite the cloud cover, convection is
already firing up on the rim this afternoon while further south
near Tucson, convection has been slow to develop as temperatures
are running excessively cooler (-15F) today from last nights rain.
The 12Z sounding from this morning shows that PWs are up to 1.8
inches in Phoenix, up 0.2 inches from 24 hours ago while there was
very little 0-6km shear (~10 kts). According to the SPC
climatology page, developed by one of our very own local
forecasters, PWs were near record climatology levels this morning
which will favor heavy rains over strong downburst winds this
afternoon. However, localized downburst gusts as we saw yesterday
are certainly not out of the question.
The latest HRRR simulation continues to shows an outflow boundary
moving through the Phoenix area between 3-6Z tonight. This
boundary, if it does form, will likely approach out of the
northeast as most of today`s convection is centered along the
rim. The big question is whether or not this outflow will be
strong enough to initiate convection again in the Phoenix area.
Local research has shown that PWs above 1.5 inches do not
necessarily translate to more severe thunderstorms warnings nor
area lightning coverage in our CWA. With that said, forcing is
likely more important when we get this saturated so a strong
outflow boundary will be needed to generate activity in the valley
tonight. Most CAMs do show some sort of boundary moving though
Phoenix, although chances of initiating convection at a particular
point remains between 10-20%.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
Through 08z Wed, weak to moderately strong convective outflow
boundaries 10-20 knots will move south through the greater Phoenix
area. Sct clds based 10-12 thsd agl with bkn cirrus above. A slight
chance of a shower or thunderstorm. From 08z Wed to 19z Wed, east to
northeast wind 5 to 10 knots. Sct clds based 10-12 thsd agl with bkn
cirrus above. Southeast California/Southwest Arizona including KIPL
and KBLH:
Southeast California/Southwest Arizona including KIPL and KBLH:
Through 19z Wed, sct clds at or above 14 thsd agl. South to
southwest wind 5 to 10 knots.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Thursday through Monday:
A gradual increase in available moisture levels to result in an
increase in humidities and monsoon thunderstorm activity through the
period. Thunderstorm coverage to rise from isolated-scattered on
Thursday to scattered-numerous by Sunday/Monday. Locally heavy rains
are possible by Sunday/Monday, especially over the higher terrain
north and east of Phoenix. Temperatures to fall from slightly above
normal levels on Thursday to near, or slightly below normal by
Sunday/Monday. Minimum humidities to rise from the 15-30 percent
range on Thursday into the 25-40 percent range by Sunday/Monday,
with good-excellent overnight recoveries.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook, Twitter, and at weather.gov/phoenix
DISCUSSION...Vasquez/Wilson
AVIATION...Vasquez
FIRE WEATHER...Percha
Area Forecast Discussion
National Weather Service Las Vegas NV
720 PM PDT Tue Jul 11 2017
.SYNOPSIS...Monsoonal moisture will slowly decrease through
midweek, with dry southwest flow reducing thunderstorm chances
across the region. A slight warming trend is possible for the end of
the week before another surge of monsoonal moisture pushes back over
the area, bringing with it a slight cool down and an upswing in
thunderstorm chances late in the weekend into next week.
&&
.MESOSCALE SUMMARY...through 11 PM PDT.
The main focus for lingering showers and thunderstorms the rest of
the evening will be Esmeralda, central Nye and Lincoln counties. Storms
over northeast Clark and northern Mohave counties should end shortly
after sunset. The circulation centered in Lincoln County a little
northeast of Caliente will continue to provide dynamic support for
convection especially on its western edge as a trailing deformation
zone lies across central Nye County. Sufficient instability will
exist for thunderstorms another hour or two over central Nye County,
but then they should largely diminish to showers for the most part.
Outflow boundaries may push into northern Clark County but the
surface analyses and satellite loops indicate it should be too
stable for new thunderstorm initiation. The most recent HRRR also
depicts most convection remaining over south central Nevada.
&&
.SHORT TERM....tonight through Thursday morning.
The circulation over Lincoln county will likely keep at least
isolated showers, if not a few thunderstorms, going through the
early hours Wednesday morning. Elsewhere, a drying trend still
appears on track over the next 36 hours which will lead to less
coverage of showers and thunderstorms Wednesday into Thursday. This
is due to the mid level high becoming centered near Yuma with the
clockwise flow pulling increasingly dry air from the southwest. The
exception will be Lincoln and northern Mohave counties where some
sufficient residual moisture and instability will remain for
isolated storms Wednesday afternoon and early evening. Temperatures
Little change in temperatures can be expected with readings near or
slightly above normal.
.LONG TERM...Thursday through Tuesday.
Slight drying and stabilization of the air mass that commences
during the short term over eastern California and southern Nevada
will carry over into Thursday/Friday. The exception will be
northwest Arizona where models indicate enough moisture and
instability around to support isolated thunderstorms at least over
the eastern half of Mohave County.
Over the weekend, mid level high center which had been suppresses to
our southeast is progged to shift northwest over eastern
Nevada/Utah. Inverted trough clearly seen on water vapor currently
over southern Texas/northeast Mexico progged to slowly drift west
into northwest Mexico providing the dynamics for likely large MCS
development over Sonora. Deeper monsoon moisture is expected by
arrive Sunday but E-W orientation of ridge axis looks to block this
moisture from sweeping that far north into southern Nevada. Its not
until Monday/Tuesday that models shift the 1.5" PW line north into
southern Nevada with H85 dewpoints in excess of 12-18 deg C. Heavy
rain and Flash Flooding threat increases with those type of moisture
profiles.
.AVIATION...For McCarran...Light and variable winds will persist
before a southwest wind pushes in around 21z-22z. Southwest winds
will be around 10-13 kts with gusts up to 20 kts through the
afternoon and early evening. Today`s late morning showers and cloud
cover helped to slightly stabilize the valley, however, thunderstorm
activity can not be ruled out through the rest of the afternoon and
evening. With thunderstorm activity expected south and north of
KLAS, there remains slight chances of gusty outflow winds -- causing
sudden wind shifts -- to reach KLAS through the rest of afternoon
and evening. Storms should begin to wane after 00z. Southwest to
west wind around 12-14 kts will stick around through most of the
night before light and variable conditions set up early tomorrow
morning. Typical diurnal east wind expected to begin around 16z-17z
and end around 21z-22z as a southwest winds pushes into the valley.
Thunderstorm activity will be limited to higher terrain Wednesday.
Few to scattered clouds expected through the evening with clearing
conditions expected overnight.
For the rest of southern Nevada, northwest Arizona and southeast
California...South to southwest winds around 10-20 kts are expected
to develop this afternoon and continue into the evening across the
Mojave Desert and southern Great Basin sites. There will be a lull
in the wind overnight before setting up again tomorrow in the late
morning/early afternoon. Although, early afternoon winds tomorrow
will favor more of a southerly wind component. A few areas of
thunderstorms are expected this afternoon and evening, with the main
focus across northern Clark, northern Mohave, Southern Lincoln
Counties, as well as Inyo and Nye Counties. Thunderstorms may
produce strong wind gust and sudden changes in wind direction. Areas
of thunderstorms should begin to see a decrease in activity later
this evening. Skies will be mostly scattered to broken this evening,
however VFR conditions are expected.
&&
.FIRE WEATHER...Monsoonal moisture will slowly decrease through
midweek, with dry southwest flow reducing humidity values and
diminishing thunderstorm chances across the region. Another surge of
monsoonal moisture pushes back over the area brining an upswing in
thunderstorm chances late in the weekend into next week.
&&
.HYDROLOGY....Not at the magnitude of runoff in late June, but
creeks, streams and rivers in northern Inyo County continue to run
higher than normal and fast from snow melt. Some road closures
continue in the area. Bishop Creek Bypass and Big Pine Creek Bypass
continue to be utilized to minimize flows through Bishop and Big
Pine. Over the past week, streamflows on Independence Creek have
stabilized with peak flows comparable to 1969 and 1983. Isolated
thunderstorms over the mountains may aid snowmelt runoff and keep
some drainages elevated over the coming days as well. Remember,
never drive through flooded roadways or around barricades. Also,
pastureland or farmland adjacent to creeks, streams or rivers could
experience areas of standing water.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
MESOSCALE SUMMARY...Adair
SHORT TERM/FIRE WEATHER...Adair
LONG TERM....Pierce
AVIATION...Boothe
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