Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/10/17
Area Forecast Discussion
National Weather Service Dodge City KS
607 PM CDT Sun Jul 9 2017
...UPDATE TO AVIATION...
.SHORT TERM...(This evening through Monday)
Issued at 206 PM CDT Sun Jul 9 2017
Broad surface high pressure both at the surface and aloft will
drive the sensible weather this weekend. The short term updates this
morning mainly keeping pace with the temperature curve of the HRRR
model, being slightly warmer through the I-70 corridor, not as hot
near EHA/LBL. Temperatures were already into the 90s before 18Z
across the west central Kansas counties. Will continue the HRRR`s
temperature trend heading through the evening hours, however it is
too quick to lower dew points. No convective concerns for at least
the next 48 hours with such warm temperatures aloft and generally
subsident pattern. Models have even warmer temperatures heading into
Monday and the entire area is likely to reach 100 degrees or warmer
Monday afternoon.
.LONG TERM...(Monday night through Sunday)
Issued at 206 PM CDT Sun Jul 9 2017
The hot and dry pattern looks to continue through the entire normal
work week. The GFS shows a surface convergence zone developing
across west central/nw Kansas by late Tuesday, but again, the mid
level temperatures look to warm for any kind of organized
development for the DDC area. Temperatures making it to the
century mark are likely through the middle part of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 607 PM CDT Sun Jul 9 2017
VFR conditions will prevail at all TAF sites through early Monday
afternoon. South winds 10 to 20kt will persist across southwest
and central Kansas through Monday afternoon as a lee side trough
of low pressure remains anchored across eastern Colorado.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 71 100 72 101 / 0 0 0 0
GCK 68 100 70 103 / 0 0 0 10
EHA 70 99 69 99 / 0 0 0 0
LBL 71 101 70 101 / 0 0 0 0
HYS 74 103 72 102 / 0 0 0 0
P28 72 99 73 100 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
855 PM CDT Sun Jul 9 2017
.UPDATE... /ADDED ISOLATED EVENING POPS NW/
A pair of outflow boundaries careening south toward South Central TX
have been generating a few showers and storms in their wakes over
West Central and East Central TX. They are moving into a more stable
air mass but will also bring a boost in low level dew points as seen
at the Brenham AWOS and in HRRR forecasts. Not much rain is expected
with the short-lived post-outflow boundary activity, and will follow
the hrrr/rap suggestion that all the showers should dissipate by
around 04z. Will update the grids to extend chances by another hour
over the east and add a sliver of rain chances for a couple hours
over the Southern Edwards Plateau. The rest of the forecast remains
on track.
&&
.PREV DISCUSSION... /ISSUED 645 PM CDT Sun Jul 9 2017/
AVIATION.../00Z TAF CYCLE/
Mostly dissipating SHRA and TSRA is ongoing just north of KAUS as of
2345Z. However, there is a low-level outflow boundary slowly shifting
south that will likely cause a brief north wind shift at 5 to 10
knots at KAUS from 00-01/02Z as it did for KEDC. The remaining SHRA
will dissipate through the next hour across south-central Texas.
Another line of TSRA exists near San Angelo but that should not make
it to KDRT and dissipate across the Edwards Plateau through the
evening hours.
VFR conditions are expected through the period with predominantly
south winds near 10-14 knots. A few gusts to near 20 knots will be
likely for KDRT Monday afternoon.
PREV DISCUSSION... /ISSUED 307 PM CDT Sun Jul 9 2017/
SHORT TERM (Tonight through Monday Night)...
IR and visible satellite images are revealing storm intensity on the
rise as cloud top temperatures reach the lower -60C to lower -70C.
This activity will continue this afternoon and early evening across
central Texas and part of the Hill Country as an upper level shear
axis moves to the south into the Hill Country and an outflow boundary
from yesterday`s convection sits between the Hill Country and the
escarpment. Any strong storm that does manage to develop has the
potential for small hail, frequent lightning strikes and localized
heavy rains. Rainfall amounts will generally range from few
hundredths to one quarter inch with isolated spots getting one to two
inches (if storms stall over same area through the period).
Once the daytime heating comes to an end, storms are expected to
diminish and come to an end between 8 or 9 pm this evening. The rest
of the night into Monday morning is expected to remain dry.
Overnight lows will range from the lower 70s across the Hill Country
to the mid 70s elsewhere.
For Monday, expect mostly sunny skies over most areas across South
Central Texas with the exception of the far eastern counties. Partly
to mostly cloudy skies are expected across the eastern counties
mainly in the afternoon. There is a slight chance for rain as the sea
breeze moves into the coastal Plains area. Overall daytime
temperatures are expected to reach the mid to upper 90s.
LONG TERM (Tuesday through Sunday)...
A relative dry weather forecast period is anticipated for the first
part of the week as the sub-tropical upper level ridge takes control
over the local weather. The upper level ridge is forecast to weaken
as an upper level inverted trough moves into our area from the east,
resulting in an increase of moisture and rain chances for Thursday
and Friday. Medium-range models guidance at the moment have different
solutions for the upcoming weekend and decided to go with lower end
PoPs until they get a better agreeable signal on the extended part of
the forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 75 97 76 97 76 / 20 20 - 10 -
Austin Bergstrom Intl Airport 74 97 75 96 75 / 20 20 - 10 -
New Braunfels Muni Airport 73 97 73 96 74 / 10 - 10 10 -
Burnet Muni Airport 73 96 73 95 73 / 20 20 - 10 10
Del Rio Intl Airport 74 99 75 99 76 / 0 0 0 0 10
Georgetown Muni Airport 74 96 75 95 75 / 20 20 20 20 10
Hondo Muni Airport 72 99 73 99 74 / 0 0 0 - -
San Marcos Muni Airport 74 97 74 96 75 / 20 10 - 10 -
La Grange - Fayette Regional 75 96 76 95 76 / 20 20 10 20 10
San Antonio Intl Airport 75 98 75 97 76 / - - - 10 -
Stinson Muni Airport 74 99 74 97 75 / - - 0 10 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Allen
Synoptic/Grids...Oaks
Public Service/Data Collection...33
Area Forecast Discussion
National Weather Service Hastings NE
734 PM CDT Sun Jul 9 2017
.UPDATE...
Issued at 729 PM CDT Sun Jul 9 2017
Updated the forecast this evening to increase the chance of
thunderstorms significantly in our northern CWA to around 50
percent near Ord, citing the storms that have held together to
the north and heading south. There seems to be a decent cold pool
helping to propagate these storms south, and along with the
developing low- level jet tonight, this could help maintain storms
longer than previously thought, and there is an outside chance we
could still have some remnants of the storm a bit past midnight.
There could be an isolated severe storm in our north, but support
for this wanes after sunset.
&&
.SHORT TERM...(This evening through Monday)
Issued at 309 PM CDT Sun Jul 9 2017
Firstly, scattered thunderstorms across the northern Sandhills
may approach the area after 0Z. Models have mostly killed off this
activity before it makes it here, but the last few ones of the
HRRR and HRRRX bring it into Valley and Greeley county areas.
Therefore, I included a slight chance in these areas.
Tonight into tomorrow morning, a cold front reinforced by outflow
from the aforementioned storms will move southward across the
area for tomorrow. Tomorrow afternoon, a few models, namely the
NAMnest and some of the NCAR WRF ensemble members, are developing
convection along the I-80 corridor in response to this front. On
the other hand the NAM/GFS/ECMWF don`t output any QPF, and
soundings look pretty capped. If something does develop, it could
be marginally severe thanks to 1500-2000J of CAPE and ~30 kts of
0-6km bulk shear. All that being said, I wouldn`t be surprised if
something isolated develops, but the areal coverage and potential
are just too low to include at this point.
The other point of interest for tomorrow is the heat. Model
guidance has lowered temperatures noticably for tomorrow as the
front looks to push a little farther south than previously
expected. There will probably be a pretty large temperature spread
across our CWA, with highs struggling to reach the low 90s near
Ord, and blasting into the low 100s in Kansas.
.LONG TERM...(Monday night through Sunday)
Issued at 309 PM CDT Sun Jul 9 2017
Precipitation chances return to northern parts of the forecast
area for Monday night as an upper level wave through the area. The
timing of this feature would have develop in western Nebraska
during the late afternoon and track into central and north-central
Nebraska overnight. In the presence of an 850mb low-level jet,
there will be enough instability that a marginal severe threat
exists with this activity as well.
On Tuesday, a tightening pressure gradient will make for breezier
conditions across much of the forecast area. This will help make
the heat feel a bit more bearable. This is a good thing, as highs
are still expected to be in the upper 90s to low 100s.
Tuesday night will bring most of the area a better chance for
rain and thunderstorms as we will have decent low and mid-level
convergence along a stalled front aided by a strong low-level jet.
Thunderstorm chances continue through Wednesday as the
aforementioned front sags southward. This will also keep
temperatures a few degrees cooler on Wednesday.
Thursday through Saturday, the weather pattern looks to remain
pretty stagnant in zonal flow, with daily chances for
thunderstorms and highs in the low to mid 90s. The GFS shows us
moving back into more northwesterly flow Saturday into Sunday,
possibly bringing us a bit cooler air late next weekend into the
following week.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 657 PM CDT Sun Jul 9 2017
Biggest issue will be low-level wind shear when the low-level jet
develops and increases overnight. Thunderstorm activity to the
north should die out before it would arrive, as much of it is
diurnally driven.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
UPDATE...Heinlein
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Wilmington NC
958 PM EDT Sun Jul 9 2017
.SYNOPSIS...
A weak cold front will stall across the area through Monday,
enhancing the risk for thunderstorms and excessive rainfall.
The front will slowly dissipate Tuesday as the Bermuda ridge
builds back across the Carolinas. The Bermuda ridge and Piedmont
trough will produce typical summertime heat and humidity and
afternoon and evening thunderstorms Wednesday through Friday.
Heat index values mid to late week will approach 105 degrees. A
cold front will approach Saturday with cooler temperatures and
better rain chances.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 945 PM Sunday...Over the past two hours the heaviest
rainfall has shifted south to a line from Conway into northern
Williamsburg County. This is quite fortunate since radar storm-
total rainfall amounts were exceeding 5 inches in spots. The
mesonet station in Green Sea, SC (Northern Horry County) has
received 4.18 inches today which is roughly 10-20 percent higher
than either dual-pol or legacy radar products indicated.
A recent chat with the WPC Metwatch forecaster was fruitful and
revealed some additional reasoning about ongoing rainfall this
evening. Most notably, a right-entrance region of a jet streak
located off the Mid-Atlantic coast sits across the eastern
Carolinas. The upper divergence within this "acceleration lane"
aloft is helping support upward vertical motion even as ongoing
convective processes stabilize the boundary layer. Outflow
boundaries have continued to focus new convection and are also
contributing to aberrant cell motion which has had a
considerable backbuilding/upstream component through the
evening.
On this latest update, I have focused the remaining heavy rain
threat across Conway, Brittons Neck, and Lake City southward to
the Santee River for the next 3 hours. New convection developing
back across the Sandhills is moving little, and may feed
eastward toward Florence and Dillon after midnight. The RAP
model is outperforming the HRRR significantly this evening.
Discussion from 800 PM follows...
Another update to the forecast to increase rainfall forecasts
to an additional 3+ inches in the area from Tabor City southward
across Conway and into northern portions of Georgetown and
Williamsburg Counties. I contemplated a short- term Flash Flood
Watch, but this event could be over in the next 2-3 hours and
will be handled by warnings at this point. Boundary collisions
and back-building cell motion continues to dump rain across the
same areas, leading to these excessive rainfall totals. Latest
dual-pol and legacy radar estimates are between 4-5 inches from
the towns of Tabor City, NC to Green Sea, SC.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...The mid level pattern will become poorly
defined across the area through the period, which is quite
typical this time of year. Any lingering fronts or boundaries
will have all but washed out leaving the standard local or
regional features to work with what will still be a very moist
airmass as precipitable water values hover near an inch.
Guidance does show a decent chance of overnight convection late
Monday into early Tuesday with a shortwave moving across from
the west. For the day Tuesday the sea breeze and Piedmont trough
will be the primary triggers. It appears as of now overnight
Tuesday into early Wednesday may see a quiet overnight period,
the first in some time as the weak flow is void of any
shortwaves. No changes to the temperature forecast which should
remain just a notch or two above climatology.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 PM Sunday...First half of the extended offers a return to
heat and humidity as mid-level ridge expands across the Southeast.
The mid-level ridge expands from the east and extends into the
Carolinas, beneath which a surface Bermuda-type high strengthens.
This will bring hot temperatures back into the region, along with
increasing humidity on return flow.
Highs on Wednesday will rise into the low 90s most locations
away from the immediate beaches, with heat index values climbing
over 100. Thu-Fri will be just as warm, and feel even hotter,
with heat index values climbing to near 105 both aftns. Scattered
diurnal showers and tstms will be possible each aftn as well,
but subsidence beneath the ridge and lack of significant mid-
level forcing will keep coverage isolated at best.
As we head into the wknd, the ridge will amplify across the mountain
west driving a longwave trough into the eastern CONUS. This will
suppress the ridge locally into the GOM, and cause increasing shower
and tstm chances as well as bring cooler, more seasonable, temps to
the Carolinas. A cold front will likely sink south into the region
at the leading edge of the trough, and then stall across the area.
This will create much more unsettled weather to the region with good
shower/tstm chances through the wknd.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 00Z...Very heavy thunderstorm activity between Florence,
SC and Wilmington, NC is backbuilding southwestward very slowly
and poses a threat to the two Myrtle Beach airports (MYR and
CRE) through the evening hours. Our latest forecast includes a
tempo group of thunderstorms and MVFR conditions developing
between 01-05Z at MYR and CRE. If a thunderstorm cell develops
directly over one of these airports, expect IFR conditions to
develop with visibility measured at less than 1 mile earlier in
Whiteville, NC.
Less certain is the potential for storms in the vicinity of the
ILM airport this evening. Radar trends indicate the heaviest storms
may remain off to the southwest. For the FLO airport we`re
watching storms advancing northward from the Manning, SC
vicinity that could pose a threat by 03Z. Beyond midnight local
time, convective activity should concentrate south of Florence
and west of the Myrtle Beach airports, potentially expanding
again after 09Z as moisture offshore begins to surge inland.
Extended Outlook...MVFR/IFR conditions are possible from
thunderstorms as a stalled front dissipates across the area
Monday night into Tuesday.
&&
.MARINE...
NEAR TERM /THROUGH MONDAY/...
As of 945 PM Sunday...The coastal waters has thus far escaped
much of the rough weather inland this evening. This may be
changing as an outflow boundary that just pushed off the coast
around Myrtle Beach may spark the development of new storms
along coast from Oak Island down across the Grand Strand in the
next hour. Outside of thunderstorms the synoptic winds remain
from the southwest around 10 knots, with seas 2-3 feet, with
little change anticipated overnight. Discussion from 800 PM
follows...
No significant changes are needed to the forecast. Today`s
seabreeze was rather anemic given the weak temperature contrasts
across the beaches, and winds are generally less than 15 knots.
Wind speeds around 10 knots from the southwest are expected
overnight, with variability near thunderstorms may which become
more common near the beaches of Myrtle Beach and Cape Fear later
this evening. Discussion from 300 PM follows...
A weak cold front will slowly dissolve upstream ahead of
building western Atlantic ridge. Sustained wind speeds into
tonight and though Mon will be 10 to 15 kt. The direction will
be S into early this eve, becoming SSW/SW tonight and Mon. Seas
will remain about 3 ft throughout. Showers and thunderstorms
with heavy rain will become numerous to widespread, especially
late tonight and on Mon.
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Bermuda High pressure will continue to be
the dominant feature across the coastal waters through the
short term period. Expect winds from the south/southwest of
10-15 knots through the period. There may be a slight
enhancement to just above 15 knots overnight Monday into early
Tuesday with the low level jet. Significant seas will be 2-4
feet.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 300 PM Sunday...High pressure centered well offshore will
expand and ridge back into the Carolinas through the end of the
week. This persists SW winds across the waters, with only slow
increase in speeds from around 10 kts Wed/Thu to 10-15 kts Friday as
the gradient pinches ahead of an approaching cold front from the NW.
This front will remain well NW of the waters through the period, but
these stronger winds late will create the highest seas of the week
on Friday. 3-4 ft seas will be common on Friday with a SW wind wave
amplifying in the spectrum, after several days of 2-3 ft thanks to a
low amplitude SE swell and SW wind wave earlier int he week.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...JDW
AVIATION...TRA
MARINE...
Area Forecast Discussion
National Weather Service Lincoln IL
830 PM CDT Sun Jul 9 2017
.UPDATE...
Issued at 825 PM CDT Sun Jul 9 2017
Warm front slowly lifting northeast across the forecast area this
evening coupled with a weak upper level disturbance tracking
across eastern Illinois produced some widely scattered thunderstorms.
Surface Capes late this afternoon were ranging from 2500-3000
J/Kg and right along and to the east of the warm frontal boundary
we have been watching some rather high 0-3km Helicity values along
and to the east of I-57. We received a public report of a funnel
cloud about 2 miles east of Tilton with a small storm that exhibited
low and mid level rotation for several volume scans before it
gradually weakened as it tracked into far western Indiana just
after 7 pm. The scattered cells to our west were dissipating early
this evening and most short term models continue with that idea
thru the evening.
Severe storms have finally developed over parts of central Minnesota
early this evening and it is from that area that we will watch to
see how the storms track into the early morning hours. The last few
runs of the HRRR model continued to show the strong storms tracking
southeast into northeast Iowa and then into northwest Illinois
after Midnight, and finally into at least the northern half of the
forecast area after 2 or 3 am. The last few model runs have
trended slower with the arrival time in our area. Highest POPs
will remain across the north late tonight and into Monday morning,
and then with numerous mesoscale boundaries left over from the
late night convection for storms to refire on again Monday
afternoon during peak heating. No major changes made to the grids
early this evening, as a result, no ZFP update will be needed at
this time.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 244 PM CDT Sun Jul 9 2017
Main concern for this period will be with convective trends.
Convective complex is expected to develop across central
Minnesota and dive southeast this evening with an enhanced threat
of damaging winds. While the apex of this expected bow echo is
projected by most of the high-resolution models to stay to our
north, they do suggest at least part of the line moving into
northern parts of the CWA overnight. The ARW indicates this could
occur as early as 2-3 am, while the HRRR focuses more on the 4-5
am time frame. Any lingering rain from this system should be out
of the area by mid to late morning.
The atmosphere is expected to have plenty of time to destabilize
in the wake of this first cluster of storms, with both the NAM and
GFS projecting surface based CAPE`s to rise to over 4,000 J/kg
during the afternoon across the northwest half of the forecast
area. The incoming cold front and/or the residual outflow boundary
from the earlier storms will provide the focus for another line
of storms to form across the northern third of the state around
mid afternoon, dropping southward. Latest SPC Day2 outlook
introduced a slight risk of severe storms for this scenario.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 244 PM CDT Sun Jul 9 2017
Ongoing concern much of the week will be with the persistent heat,
as the warm air mass that has been prevalent over the west half of
the U.S. spreads eastward. Current indications are that
traditional heat advisory levels (heat index at least 105 degrees)
would not necessarily be met, but an advisory could be warranted
due to the duration of 100+ degree heat indices. Right now, it
appears Thursday provides enough of a question mark due to
convective issues to hold off on any advisories, but will continue
to hit the issue hard in the Hazardous Weather Outlook.
In terms of the convection, a zonal flow will be setting up early
this week, with periodic waves riding along it. As such, it will
be tough to get any extended rain-free periods, although the rain
should not be continuous. Early on, much of the northern and
central CWA will see the main focus for this, as any surface
boundaries would not have much of a reason to move out of the
area. However, by about Thursday, a rebuilding of the western
ridge will get the Great Lakes back into more of a northwest flow,
which will help Thursday`s front push further south toward the
Ohio Valley. As such, PoP trends significantly drop off late in
the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 545 PM CDT Sun Jul 9 2017
VFR conditions are expected through the forecast period. Main
forecast concern will be timing of a complex of storms that will
be forming in central Mn in the few hours and then shifting
southeast later this evening. Latest high resolution forecast
models suggest the timing in our northern TAF sites, including
CMI, would be from 08z-10z. The potential with these storms late
tonight/Monday morning will be strong shifting winds into the
north and northwest along with lower cigs/vsbys in brief heavy
rain. At this point, confidence still not that great with respect
to the storms reaching SPI and DEC by dawn Monday, so will lean on
keeping any mention out at this time. Convection and any
restrictions to vsbys and cigs, should move out of our area by
late morning on Monday with the potential for storms to redevelop
after 20z across the forecast area. Surface winds will be south to
southwest tonight at around 10 kts but if storms affect a TAF
site, winds will be variable in direction, mainly from the north
to northwest, with gusts up to 40kts possible along the surging
outflow boundary, especially at PIA and BMI. Away from storms on
Monday, surface winds will be southwest at 12 to 17 kts in the
afternoon with a few gusts up to 23 kts at times.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Smith
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Smith
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
745 PM EDT Sun Jul 9 2017
.UPDATE...
Issued at 720 PM EDT SUN JUL 9 2017
Did an update to the grids through the rest of the evening. Mainly
adjusted the Sky and added the latest T/Td obs and trends. These
have been sent to the NDFD and web servers.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 440 PM EDT SUN JUL 9 2017
20z sfc analysis shows high pressure in control of the weather
across eastern Kentucky making for plenty of sunshine, comfortable
humidity levels, and pleasant afternoon temperatures in the upper
70s and lower 80s. Fair weather cu is found locally through far
eastern parts of the area with other high clouds impacting the
region as they work southeast through the Ohio Valley from
northern Illinois and Indiana. Meanwhile, winds are light and
variable with dewpoints running in the mid to upper 50s.
The models are in good agreement aloft through the short term
portion of the forecast. They all depict several notable
shortwaves rotating through the deep eastern trough over the
region. A weak one is exiting to the east of Kentucky this
afternoon with a more substantial one passing to the north by 18z
Monday. Another one will follow on its heels approaching the area
by 12z Tuesday. Despite the small scale nature of these features
the models have them similarly represented lending some confidence
to their individual wx details. Given the model agreement will
favor a general blend with significant deference given to the
higher resolution HRRR and NAM12 specifics.
Sensible weather will feature a quiet night with mostly clear
skies through the bulk of it. This will lead to patchy valley fog
forming again late tonight along with another decent ridge to
valley temperature split. Owing to dewpoints falling into the
upper 50s most places this afternoon have allowed the temps to
fall a bit more than CONSShort and MOS. Towards dawn we will have
to watch for potential outflow driven convection impacting our
northern zones per the latest HRRR and NAM12. The threat will
linger through the day as boundaries will likely settle south into
our area generally north of the the Mountain Parkway. Moisture
and warmth will build up during the day, as well, fueling the
storm potential for those northern locations. For Monday night, we
still could see a mild ridge to valley difference as the diurnal
clouds diminish but milder conditions and higher dewpoints will
limit the temperature drop off. There will be another threat of
showers or a storm late at night from the northwest, but likely
not until after dawn - again just affecting our northern counties.
Look for some patchy fog in the valleys through dawn Tuesday, as
well.
Used the CONSShort as the starting point for all the grids with
adjustments tonight and, to a lesser extent, Monday night for
ridge and valley distinctions. Also, tweaked the blended guidance
PoP grids to allow for more of a lingering threat of convection
through the day Monday, mainly in the northeast.
.LONG TERM...(Tuesday through Sunday)
Issued at 400 PM EDT SUN JUL 9 2017
As the period starts, we should be positioned near the southern edge
of the prevailing westerlies aloft, with a surface ridge over the
southeast CONUS. A cold front is expected to be heading south into
the Ohio Valley. With the flow being zonal, the front will lose
momentum as it approaches. Models show some discrepancy as to how
far south it will make it, with the NAM being most progressive, and
the ECMWF the least. In light of the various scenarios, the southern
part of the area was kept dry, with low POPs in our northern
counties Tuesday into Tuesday night.
A low pressure system tracking east over the Great Lakes region on
Wednesday should draw the front back north, leaving us without any
significant features to support precip. Mid-upper levels are
expected to be fairly dry, with the deeper tropical moisture to our
south. That being the case, it`s a dry forecast area wide at this
point for Wednesday and Wednesday night.
Models show a cold front dropping south into our area Thursday and
Friday, trailing from the departing aforementioned storm system. A
synoptic scale upper trough is also expected to amplify over the
eastern CONUS late in the week. Models disagree on how deep the
trough becomes and how effectively we dry out behind this front, as
well as the potential for another cold front on Sunday. However,
there is enough overlap in their solutions to focus the highest POP
on Thursday night at this point. Much lower POPs have been use from
Friday night trough the weekend, pending better agreement in the
models as the time period draws closer.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 745 PM EDT SUN JUL 9 2017
For the bulk of the TAF period VFR conditions will prevail at all
sites. However, some patchy fog may affect SME towards dawn and a
tempo for BR was continued in its TAF. Will also need to watch
for any lower clouds, or even the potential for a shower or storm,
intruding from the north Monday morning at SYM as an cluster of
convection could be passing by through southern Ohio per the
latest NAM12 and now HRRR solution. Will monitor this threat and
address it as needed in future updates. Winds will be light and
variable through the period - outside of any stray storms.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...HAL
AVIATION...GREIF
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
923 PM CDT Sun Jul 9 2017
.UPDATE...
923 PM CDT
Evening Update...
Convection had taken a bit longer to initiate over
western/central MN late this afternoon/early this evening than
earlier CAM guidance had depicted. Not surprisingly, the overall
trend in HRRR runs (and new 00Z NAM) has been to slow the
southeastward evolution of evolving MCS a bit later tonight,
to beyond 2-3 am. Some runs do depict some convective development
ahead of the main line however, with warm advection wing elevated
storms depicted over parts of northeast IL, southeast WI or Lake
MI. Very late night diurnal timing perhaps supports a lower
overall severe threat, and SPC has trimmed the enhanced risk out
of the cwa to the northwest. Still, development of low level jet
should aid in spreading reservoir of 2000-3000 J/kg MUCAPEs
across the region within region of 40-50 kt effective bulk shear,
which should still support a severe potential for hail and
isolated damaging wind from stronger cores and with the eventual
arrival of the linear MCS late tonight/early Mon AM. Overall
messaging remains similar other than the slightly later timing and
slightly lower widespread severe threat.
Otherwise, a couple of isolated storms over southeast cwa had
shown some intensification with mid-level rotation earlier, though
these are weakening now after sunset. Have made updates to hourly
pop/wx grids based on radar trends in our southeast this evening,
and have slowed up pop increase from MN storms a couple of hours.
Otherwise, forecast appears generally on track.
Ratzer
&&
.SHORT TERM...
200 PM CDT
Through Mid-day Monday...
Afternoon satellite pictures reflect the surface analysis of
increasing low level moisture which is advecting in from the
southwest this afternoon. A cumulus field is blossoming along and
ahead of this moisture gradient. Instability has build
significantly in this area, but there has been limited forcing to
this point. There is some weak forcing passing through in the
northwest flow aloft that look to kick off a few largely isolated
to maybe widely scattered showers and or storms south and west of
the Chicago metro area. DCAPE will increase ahead of this wave
such that gusty winds, brief heavy downpours are possible, with
CAPE in the hail layer but somewhat weak shear indicating a lower
hail concern.
Focus will shift to the overnight hours. Temperatures will fall
initially but will slow the decline this evening and increasing
humidity will continue its northeastward progress into northeast
IL and northwest IL. This will maintain instability out ahead of
an upper level disturbance across the Upper Midwest. Earlier
forecast soundings depict an impressive wind field aloft ahead of
this disturbance. The low level wind field being from the
southwest and increasing overnight will also maintain ample
instability ahead of the wave. Short term guidance has been in
relatively good agreement in developing a complex of thunderstorms
across central MN this afternoon. There is also good agreement
this system will likely evolve into a line of storms, with the
main hazard being damaging winds, though some hail and heavy rain
may also occur. The main timing will be after 12-1 am across
north central IL, and spreading to the Chicago area around 2-3 am
or so before continuing to the southeast. The main push of the
line will be through the remainder of the area by 7 am.
SPC outlook has expanded the Enhanced risk (or locally highest
risk) across north central IL. The main upper wave does pass along
our northern tier which would limit the upper support for the MCS
farther southeast, but the Slight risk does extend through most of
the Chicago area, thus expect at least some scattered stronger
winds farther south, as the MCS parameters remain favorable at
least into portions of northern IL for the expansion of the severe
concerns, with most areas expected to get in on at least some
thunder activity during the overnight hours, lingering a bit
longer into the morning rush across northwest Indiana. There
should be a lull in activity in wake of the MCS, but guidance does
shift winds back to SW and indicates atmospheric recoveries will
set the stage for more thunderstorms for some areas later in the
day. More discussion on this portion of the forecast to come, but
a Slight risk has been added for the southern third of the area
at this point (I-80 corridor southward)
KMD
&&
.LONG TERM...
237 PM CDT
Monday Afternoon through Sunday...
An increasingly muggy air mass over the area Monday afternoon
will be undergoing recovery after the aforementioned MCS. Surface
low pressure around 1006 mb is expected to be located in the
IA/IL border area by mid-afternoon, though a fair amount of
uncertainty on the latitude of this feature, which along with
solar insolation will determine how far north air mass recovery
will occur. Southwest surface winds ahead of the low gusting to 25
mph should advect an increasingly buoyant air mass up to and even
north of the outflow boundary(ies) from the morning convection,
with dew points in the lower to mid 70s and temperatures probably
to bounce back into the mid to upper 80s areawide (assuming
onshore morning flow turns back offshore). Even lower 90s, with
head index around 100, could spread into the southern/southwestern
forecast area.
Model guidance shows fair spread on placement and re-initiation
time of convection, but it does generally agree on storm
development in a west-southwest to east-northeast corridor
associated with the outflow/modulated frontal boundary across the
forecast area during the mid-afternoon through early evening. At
least scattered storms focused on this convergence make sense
with convective temperatures in the upper 80s especially if a
subtle mid level short wave moves over the area as advertised by
a majority of guidance. The axis most favored for late day
redevelopment would be along or slightly north of the northern
edge of the current SPC Day 2 Slight Risk.
High values of MLCAPE of 2000-3500 J/kg and modest deep layer
shear of 25-35 kt would support organized storms, with ample
amount of that shear in the 1-3 km layer, supporting some rotating
updrafts aiding in large hail. Even significant (larger than golf
ball size) hail would seem possible with any supercell storms
that can develop during or shortly after peak heating, assuming
the model handle on the environment south of the outflow affected
region is correct. Storm motion should be substantially slower
than the late tonight activity, warranting concerns for heavy
rainfall and localized flash flooding given rich column moisture.
Any storms that do develop should evolve slowly southeast,
possibly with some multi-cell induced cold pools. By Tuesday
morning this should be draped along/near the southern CWA edge.
Guidance spread is large on how quickly this front progresses
north and how active it is on Tuesday and Tuesday night. Spread
chances of storms back north. As an upper trough digs into eastern
Canada during midweek, surface low pressure around 1006 mb will
move east into the Great Lakes on Wednesday, with its warm sector
likely maximized over the area that day, supporting lower to mid
90s. Associated instability ahead of the system cold front will
support a regional risk of scattered strong to severe storms given
the fast-paced mid-level winds.
Global guidance and the GFS ensemble agree that the rich low-
level theta-e air will be shunted south by Thursday, though
possibly not very far so certainly within the envelope of
uncertainty that the southern forecast area could have continued
storm chances late in the week. Slightly less active northwest
flow forecast though may support a less active period from then
into next weekend.
MTF
&&
.AVIATION...
For the 00Z TAFs...
634 pm...Main forecast concern is thunderstorms early Monday
morning and again Monday afternoon.
Thunderstorms are expected to develop over central MN over the
next few hours and quickly spreading southeast late this evening
reaching the terminals during the predawn hours Monday morning.
Confidence on timing is only medium so maintained timing from
previous forecast. Some tweaks to timing are possible with the 03z
tafs. These storms are likely to have a wind shift/outflow with
them...shifting winds to the north/northwest. Behind this line of
thunderstorms...winds will likely be erratic for a few hours...
possibly starting east or southeast then turning back southwest by
mid morning Monday.
A weak area of low pressure will move across the area Monday
afternoon into Monday evening and is likely to trigger additional
thunderstorm development across northeast IL and over southern
Lake Michigan in the mid/late afternoon. Confidence is only medium
on location and timing but opted to change mention to tempo with
this forecast. These thunderstorms are expected to push an
outflow/wind shift to the northeast across the Chicago terminals
during the late afternoon. Confidence is high for a wind shift to
the northeast...but timing will need to be adjusted as trends
emerge later Monday. Once these thunderstorms move east/southeast
of the terminals...the rest of Monday evening is expected to be
dry.
Southwest winds may remain in the 10-15kt range this evening
turning more southerly ahead of the storms. In between storms on
Monday...southwesterly winds may become gusty for a time and then
turn more westerly or northwesterly before the shift to the
northeast noted above.
Behind the first line of storms Monday morning...there could be a
period of mvfr cigs and possibly some light fog. And behind the
second line of storms Monday afternoon into Monday evening...
there could be a better chance for mvfr cigs especially into
Monday night as the surface low departs with moist low levels and
light winds. cms
&&
.MARINE...
251 PM CDT
The concerns with the Lake Michigan forecast are 1.) likely
thunderstorms over the southern part of the lake late tonight
into early Monday morning and 2.) winds shifting north on Monday.
Southerly winds will continue for a bulk of tonight, with storms
expected to develop across Minnesota and track across southern
Wisconsin and northern Illinois. Southern Lake Michigan may only
get a glancing blow with these storms, however they should be
gusty nonetheless, and could have some gusts over 35 kt including
in the Illinois and Indiana nearshore between 3 am and 7 am.
Behind these storms, the winds will briefly shift northwest over
the southern part of the lake, before probably some variability
mid to late morning. As a front drops south across the lake on
Monday winds will turn north for good, likely from north to south.
The frontal boundary will retreat north Tuesday night into
Wednesday ahead of low pressure which will move east across the
central part of the lake midday to later Wednesday.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1039 PM EDT Sun Jul 9 2017
.SYNOPSIS...
An inland surface trough and the Bermuda High will be the main
features for this week. A cold front will approach from the
northwest next weekend.
&&
.NEAR TERM /UNTIL 7 AM MONDAY MORNING/...
As of 1030 pm Sun...Thunderstorms from earlier tonight have
weakened or moved out of our area. The latest HRRR continues to
have a good handle on the overnight and will let our forecast
stand. After a lull the next few hours, an area of showers with
thunder now southwest of Wilmington will gradually spread
northeast and impact especially coastal areas. Precip chances
will drop off especially the farther inland you live. Lows
range from the lower 70s well inland to upper 70s Outer Banks.
&&
.SHORT TERM /7 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
As of 3 pm Sun...In place of the dissipated front, the typical
mid-state surface trof sets up once again with the Bermuda High
offshore. With deeper moisture axis and short wave shear axis
lingering across area, models continue to indicate scattered to
broken coverage of convective activity with greatest coverage
along the coast and keeping POPs mainly in 30-50% range.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
As of 330 PM Sunday...Guidance remains in good agreement and
continuity during period with return to more zonal flow aloft
midweek followed by troughing and cold frontal intrusion
Friday-Sunday. Only significant change to previous forecast was
to drop POPs Wed night with all models indicating no precip.
Monday night through Tuesday night...Mean upper trough over the
eastern CONUS will gradually weaken during period with stalled
surface boundary dissipating across area. With deeper moisture
axis and short wave shear axis persisting across area, models
continue to indicate scattered to broken coverage of convective
activity with greatest coverage along the coast and keeping POPs
mainly in 30-50% range. Temps near normal Monday night, then a
couple degrees warmer Tuesday with building heights.
Wednesday through Thursday...Models continue to show
ridging/zonal flow for Wed-Thu resulting in return of offshore
high/inland trough pattern, leading to warmer temps and less
coverage of convective activity. POPs will reflect typical 20%
coast and 30 to 40% inland during the day and slight chance at
night. Thicknesses peak this period around 1420-1430m supporting
highs in the mid 90s inland and upper 80s to around 90 along
the coast. Heat indices are expected to reach 100-105 each
afternoon.
Friday through Saturday...Shortwave energy digs across the
Great Lakes and across the mid-Atlantic States late in the week
with an attendant cold front approaching the region from the
northwest which will bring increased chance of tstms all zones
for Friday into Saturday. Latest GFS and ECMWF in general
agreement that front will move into area Saturday and then
quickly wash out Sunday. Temps expected to be a couple degrees
cooler with highs around 90 inland to mid to upper 80s coast.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Short Term /thru Mon/...
As of 740 pm Sunday...Generally VFR through the forecast period
outside of convection. Included some brief IFR at KISO over the
next hour with storms to the southwest of the terminal now. As
this area of storms dies down after 03Z, expect mainly VFR
overnight with higher chances for thunderstorms closer to the
coast. There should be enough high cloudiness around tonight to
preclude most fog/stratus but a few patches may occur if clouds
thin again early in the morning, but not enough confidence to
include at this time.
Thunderstorms are again possible all terminals from mid morning
on Monday.
Long Term /Monday night through Friday/...
As of 330 PM Sunday...Pred VFR conditions at the terminals
expected through the long term, but there will bouts of sub VFR
conditions in showers/thunderstorms. There will also be
occasional sub-VFR conditions during the early morning hours
with the threat for stratus and/or fog.
&&
.MARINE...
Short Term /thru Mon/
As of 1030 pm Sun...Latest obs show waves 2 to 3 feet and
southwest winds 10 to 15 kts, with our forecast in good shape.
Mostly light winds and seas through the short term with the
Bermuda High the main feature. Southwest winds will average 5-10
knots on the rivers, and 10-15 knots on the coastal waters with
seas averaging 2-4 feet.
Long Term /Monday night through Friday/...
As of 330 PM Sunday...Surface pattern will return to offshore
high and inland trough pattern through rest of week. Expect
S/SW winds around 10-20 kt and seas generally around 2 to 4 ft
but could build up to 5 ft at times across the outer coastal
waters.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...HSA
NEAR TERM...EH/HSA
SHORT TERM...HSA
LONG TERM...JBM
AVIATION...JBM/EH/HSA
MARINE...JBM/HSA
Area Forecast Discussion
National Weather Service Omaha/Valley NE
623 PM CDT Sun Jul 9 2017
.SHORT TERM...(Tonight through Wednesday)
Issued at 330 PM CDT Sun Jul 9 2017
Forecast concerns will primarily be temperatures/oppressive heat
for parts of the area/if a heat advisory is needed/frontal
location and clouds too...then if/where any storms may develop.
The latest visible satellite imagery shows the bulk of the
cloudiness over the Upper Mississippi Valley in the warm air
advection zone/mid-level omega/area north of the surface warm front.
The 12Z upper air maps showed 20-40m ht falls over the Norther
Plains and this area east of the h7 10deg C isotherm. At h85...low
pressure was over North Dakota with a 45kt h85 jet. Locally our
sounding had a pwat of 1.24 inches and elevated instability above
750mb.
20Z surface metars highlight surface low pressure over north
central South Dakota with a couple of pre-frontal troughs and
progressive drying/lower dewpoints. Locally temperatures were in
the 90s with dewpoints in the 60s to lower 70s...however in
central Nebraska the dewpoints were in the 50s and in the 30s and
40s for the Nebraska Panhandle. temperatures had warmed to 108
degrees at VTN with a northwest wind gusting to 20kts.
The focus for thunderstorms tonight and Monday will be where the
forcing and the moisture/instability will be most prevalent and this
will be over the Upper Mississippi Valley into the Great Lakes and
Ohio River Valley as the upper level jet drives shortwave energy
through the h5 trof. SPC has an enhanced are for severe weather as
storms develop near the surface low and is pulled high cape
(5000j/kg) and northeast of the 8.5+ steep mid level lapse
rates/50kts effective bulk shear vectors.
Locally...ridging will develop over the Western High Plains
aloft, however cooling will take place at h85 and at the
surface...although this will be modified. Although cannot rule out
a few isolated storms as a few showers and thunderstorms from the
Black Hills/northern Nebraska tend to dissipate as they head
toward the local cwa or later tonight with energy dropping south
across Iowa. The CAMs are mainly dry save for the more recent HRRR
lat holds on to precip toward Neligh/Albion/Columbus. The 12Z
NAM12 hints at some isolated activity near SUX Monday morning
along with the Canadian/SREF and the NAM/Canadian/EC/SREF/ARW/NMM
have a signal near the MO/KS border Monday at 00Z. The 18Z hints
at some activity similar to the more recent HRRR through 03Z this
evening. Will match up with GID to include a small pop early this
evening. A stronger signal Monday night with the boundary lifting
north into late Monday into Tuesday.
The temperature forecast for Monday has a large bust potential and
will be difficult as it will depends on how strong the push is
with the storm system/storms to our east and how much cloudiness
develops behind the front. MOS guidance is in the 80s at KOFK and
in the 80s with the MET guidance for OMA and 94 with the MAV
guidance. Dropped highs across the northern parts of the forecast
area, however held highs near the KS/MO border in the 95 to 100
degree range. With moist dewpoints, this pushed them into a heat
advisory where heat index values of 105 t0 110 are expected. The
night shift can further refine this, however in coord with TOP/EAX
will issue a heat advisory for Monday.
The front will be a focus for storms Monday afternoon along with
the passage of a weak weather disturbance, thus for now did
include chance for storms near the KS/MO border. With moisture
pooled in this area and mid level warm advection and shortwave
lift, overnight thunderstorms will be possible and these would
continue Wednesday.
.LONG TERM...(Wednesday night through Sunday)
Issued at 330 PM CDT Sun Jul 9 2017
The extended has the mid tropospheric ridge anchored over the
western U.S. and varying solutions as to the eastward extend of
the ridge. Spotty precipitation is still in the forecast Wednesday
night through Saturday...with cooler highs in the 80s for the
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 622 PM CDT Sun Jul 9 2017
VFR conditions are expected through the TAF cycle, with
unrestricted visibility and mid- to high-level clouds. South winds
will slacken and become southwesterly this evening. Low-level
wind shear is possible tonight at all sites, but particularly at
KOMA/KLNK. Winds will become light and variable/shifting from
Monday morning through the day.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory from noon to 8 PM CDT Monday for NEZ088>093.
IA...None.
&&
$$
SHORT TERM...Zapotocny
LONG TERM...Zapotocny
AVIATION...Mayes