Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/05/16
Area Forecast Discussion
National Weather Service Bismarck ND
1039 PM CDT SUN SEP 4 2016
.UPDATE...
Issued at 1037 PM CDT Sun Sep 4 2016
Cancelled the watch as the threat for severe storms has ended
across the James River Valley. Otherwise no change to the
forecast.
UPDATE
Issued at 946 PM CDT Sun Sep 4 2016
Models have backed off on pops west late and now not till after
12Z so scaled back during the overnight period west. Otherwise,
widespread showers and thunderstorms continue over my southeastern
counties. Still ample shear and instability though do think the
overall severe threat has diminished. Feel better leaving the
watch as is for now with this update given SPC mesoanalysis, but
am confident we can let it go before midnight.
UPDATE
Issued at 742 PM CDT Sun Sep 4 2016
Greatest threat for thunderstorms remains over the far south
central and into the James River Valley this evening around a
stationary frontal boundary. Thus far no severe weather in my
southeast, though instability and shear parameters still elevated
enough for an organized storm or two to develop for the next few
hours, so will maintain the Severe Thunderstorm Watch as is with
this update. Tampered down pops central and west until the
overnight when the next wave lifts towards the Northern Plains.
UPDATE Issued at 500 PM CDT Sun Sep 4 2016
Quick update to issue a Severe Thunderstorm Watch for Logan,
LaMoure, McIntosh, Dickey Counties.
&&
.SHORT TERM...(This evening through Monday)
Issued at 246 PM CDT Sun Sep 4 2016
The main focus for the short term is potential severe thunderstorm
chances this afternoon and evening across the southern James
Valley.
A trough centered just east of Bismarck this afternoon will be the
focus for thunderstorm development. A slight clear patch in the
clouds across south central North Dakota has allowed temperatures
to climb into the 70s. The latest HRRR run indicates convective
initiation around 6 PM across far south central North Dakota. The
bulk of the instability should remain along and just south of the
ND/SD border. However, storm motion could bring stronger storms
across northern South Dakota into Emmons, McIntosh and Dickey
Counties later this evening. Plenty of moisture and shear will be
present along the front to sustain storms once they develop. The
main trough will exit the area tonight, with a slight break in
the shower/thunderstorm activity overnight before another wave
moves into western North Dakota Monday morning. Very high PWAT
values and training storms could create some hydro issues later
tonight with rainfall rates greater than an inch an hour.
Thankfully impacts should be short-lived as a break in the action
is expected overnight.
.LONG TERM...(Monday night through Sunday)
Issued at 246 PM CDT Sun Sep 4 2016
The rest of the week looks cooler and active as a broad cyclonic
flow will remain over the northern plains with several shortwaves
moving through. The most models highlight Wednesday for the best
chance for showers this coming week as a pronounced shortwave
moves through. There is a chance for showers and thunderstorms
through Saturday. Monday will be the coolest with upper 50s
northwest and 60s southeast. Then highs will be in the 60s to
lower 70s for the remainder of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 742 PM CDT Sun Sep 4 2016
Thunderstorms will impact the James River Valley this evening
including KJMS. Elsewhere mainly isolated showers this evening
until after midnight when we will see increasing chances for
showers west then into the central towards 12Z. MVFR cigs with
localized IFR cigs area wide through much of the 00Z period. Also
potential for reduced visibilities in precipiation and/or fog.
&&
.BIS Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...MM
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...NH
Area Forecast Discussion
National Weather Service Grand Forks ND
939 PM CDT SUN SEP 4 2016
.UPDATE...
Issued at 933 PM CDT Sun Sep 4 2016
Primary concern has transitioned from severe threat to areal
flooding concerns as deep moisture convergence over the sfc
boundary, which has barely moved since the 7 PM CDT update,
continues to dump heavy rain from roughly a Warroad MN to Grand
Forks ND to Valley City ND line. Main adjustments to grids are
extending the categorical POPs well into the overnight period and
also increasing QPF amounts along this band of activity. Severe
threat remains well to the south however an evolving MCS over s
central SD is progged by HRRR to lift through our southeastern
zones in the midnight to 6 AM timeframe. Could result in eastward
expansion of severe box depending on wind damage reports/potential
across central and eastern SD. For now, appears threat to Ransom-
Sargent-Richland counties is diminishing.
UPDATE Issued at 601 PM CDT Sun Sep 4 2016
Current METARs indicate a well defined surface boundary extending
from Baudette MN to Hillsboro ND to Forbes ND before extending
through central SD. The eastern and southern side of this
boundary, mainly over the southern RRV and west central MN,
continues to have plenty solar with temps around 80. Meanwhile,
the best deep layer shear remains along and west of the boundary.
Main severe threat will be in southeastern ND as the boundary
moves east into the area that heated out this afternoon. Slow
progression of boundary will generally keep regions east of the
valley out the threat area. A severe thunderstorm watch is now in
effect for Ransom...Sargent and Richland counties through
midnight. Have adjusted wx grids for severe wording and increased
POPs to categorical across the north.
&&
.SHORT TERM...(This evening through Monday)
Issued at 305 PM CDT Sun Sep 4 2016
Forecast challenge in the short term will be T coverage/severe
potential. Earlier today high resolution models struggled with
current convection with RAP and HRRR doing the best of late. HRRR
has improved over the last several hours leading to somewhat
higher confidence on what will happen overnight.
Boundary from northern valley to near JMS and into central SD will
drift slowly east overnight. Clouds/rain have limited instability
especially across the northern two thirds of the forecast area.
Airmass becoming increasingly unstable from the far SW FA into SD.
This appears to be the favored location for convective initiation
later this afternoon or early evening. Convection will likely then
propagate NE along the boundary during the night so it may be
later before northern portions of the region from the valley west
get rain. Severe threat looks to be limited to the S-SW fa.
By morning boundary will be bisecting the FA from NE-SW.
Convection will probably be ongoing in the am most likely over the
ne fa. At prime heating front will be across the far se fa and
will have to monitor for severe potential there. Across the
remainder of the fa will maintain some chance pops but would not be
surprised if most areas stay dry. Column steadily cools during the
day with warmest readings over the far E-SE closer to the
boundary.
.LONG TERM...(Monday night through Sunday)
Issued at 305 PM CDT Sun Sep 4 2016
An upper level wave will be moving through the region on Monday
night. Models have surface low in eastern SD/SW MN Monday at 7 PM.
Most models have an inverted trough/cold front extending NE from the
low to the Arrowhead of MN...although the GFS is further west with
the front. There will likely be some elevated instability in the SE
forecast area, including the Fergus Falls and Wadena areas, Monday
evening. With effective shear of 40-50kts and MUCAPEs of 1500-3000
J/kg, a threat for severe storms will exist. A sharp theta-e
gradient will exist along the cold front...with a strengthening low
level jet by 10 PM. The front gets a nudge eastward later Monday
night as the upper wave passes to the north.
Tuesday looks generally dry with highs in the mid 60s north to mid
70s south and partly sunny skies. Another wave will bring a chance
for showers/thunderstorms on Wednesday/early Thursday. Yet another
wave will affect the area on Friday. All in all the pattern looks
active with highs generally in the mid 60s to mid 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 601 PM CDT Sun Sep 4 2016
Thunderstorms will impact sites along and north of the Highway 2
corridor early in the evening and spread into FAR/BJI areas over
the next several hours. Low MVFR/IFR cigs expected to fill in
behind convection and continue through the night into late
tomorrow morning. Not ideal flying conds over the next 18 hours.
FAR will have a break through mid evening before cells begin
impacting its aerodrome.
&&
.FGF Watches/Warnings/Advisories...
ND...None.
MN...None.
&&
$$
UPDATE...Speicher
SHORT TERM...Voelker
LONG TERM...Knutsvig
AVIATION...Speicher
Area Forecast Discussion
National Weather Service GLASGOW MT
837 PM MDT SUN SEP 4 2016
.SHORT TERM...for northeast Montana...tonight through Tue...
Update...
Due to a dry boundary layer, light rain has been slower to reach
the ground across parts of the forecast area than expected.
Nevertheless, radar echoes are present, especially across western
and central portions of the CWA. Although the steadiest rain so
far has occurred over parts of southern and central Montana, the
expectation is still that this activity will spread further north
and east overnight and on Monday as the boundary layer reaches
saturation and as forcing for ascent increases when an absolute
vorticity maxima reaches the area presently indicated over
southern Idaho on water vapor imagery. Overall expect widespread
wetting rains to still be on track, though perhaps amounts may be
somewhat lower than previous expectations given the delayed start
to the event. Maliawco
Previous Discussion...
A large trough of low pressure aloft is entrenched over the
northern Rockies region which places northeast Montana in a steady
moist SW flow aloft. Unfortunately, the precipitation models have
a difficult time pinning down the variable rain bands that result
from these dynamics. The HRRR and EC and the GEM seem to be the
more accurate models while the GFS and NAM are of next to no help
at all. Tried to blend the best consensus I could find for all
adjustments to the forecast. Because of the variable nature of
these rain showers, would not be surprised if some locations
accumulate over an inch of rain while others only receive a trace
of rain.
Tonight: The first wave of precipitation continues to do what it
has done for most of the day already - concentrate more over our
southern zones, making feeble attempts to extend northward toward
the international border only to peter out to just a trace.
Monday: The closed upper low center becomes an open wave and moves
directly over northeast Montana. The models improve just a bit
with consensus on the precip amount and placement. Best chances
for accumulating rain will be between Monday morning and Monday
afternoon and could easily be a bit more widespread than what we
experienced today.
Monday night the upper level wave weakens and lifts northeastward
over Saskatchewan and ends the rain from SW to NE across many
locations by the overnight hours.
Tuesday as the flow becomes more zonal, only lingering chances for
trace to minimal amounts of rain can be expected over our NE
zones.
Expect temperatures around 20 degree below averages for this time
of year through Tuesday morning as the cold continental air mass
from Canada continues to hold sway. BMickelson
.LONG TERM...Tue night through Sun...
Going forecast has a good handle and 12z models didn`t provide
much need for change. At the end of the period, a disturbance
brushes the area from the north and could knock temps dwon along
with bringing the chance of showers. TFJ
Previous Discussion...
Cool conditions expected from midweek through next weekend with
longwave upper trof over North America. Lowered heights and the
southward shift of the jet will keep temperatures below normal for
the period.
Main chance for rain will be with a shortwave trof pushing
through the northern Rockies midweek. System tracks along the
Canadian border with thunderstorms possible ahead of the low
Tuesday night into Wednesday. A second wave follows on Thursday
but models differ on how far south it dips so uncertainty is
increased regarding rain chances. Ebert
&&
.AVIATION...
A large upper level trough will continue to dominate the weather
pattern for the next 24 hours. This will bring isolated areas of
light rain to the region.
Expect VFR conditions with areas of MVFR in heavier rain.
Wind will continue out of the Northeast under 15 knots.
Proton
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Hastings NE
711 PM CDT SUN SEP 4 2016
.UPDATE...
Issued at 659 PM CDT Sun Sep 4 2016
Diurnally driven strong to severe thunderstorms across northwest
Kansas will slide northeast into our north central Kansas and
south central Nebraska counties this evening. These storms will
likely be more scattered in coverage south of interstate 80 and
there is some question as to how well they will hold together
after sunset, but large hail, damaging winds, and flash flooding
will be possible with these storms. Additional strong to severe
thunderstorms are expected to form on the nose of the
strengthening low level jet between 9pm and midnight with the
greatest coverage of these later developing storms likely north
of I-80 and even more so along and north of hwy 92.
&&
.SHORT TERM...(This evening through Monday)
Issued at 227 PM CDT Sun Sep 4 2016
We have a chance for thunderstorms this evening. There will be a
couple thousand J/kg of most unstable CAPE (upwards to near 4,000
per the NAM) with decent bulk (0-6km) shear around 45 knots to
support updrafts capable of large hail around half dollar size (or
larger) and thunderstorm wind gusts around 60 mph. Initially,
there is a chance for some of the early thunderstorms to develop
into supercells and there will be a small threat for tornadoes
before storm mode goes more into a cluster of storms. The higher
instability is across western portions of the county warning
area...and I believe thunderstorms will impact our area here
initially. A surface trough is currently in place across western
parts of the Central Plains. Thunderstorms are already developing
across eastern Colorado. The HRRR is initializing well and
capturing this in the 19Z run. The HRRR brings these storms into
western parts of our area as early as 6pm.
A flood warning is in effect for portions of north central Kansas
until 730 pm tonight. Please see the latest Flood Warning product
for more information. Chances for additional rainfall look more
favorable for areas north of the flooded area.
.LONG TERM...(Monday night through Sunday)
Issued at 227 PM CDT Sun Sep 4 2016
Throughout the extended there are multiple chances for
thunderstorms. Some of these chances could produce storms capable
of strong to severe weather. The Storm Prediction Center has us
outlooked the next several days in a row. Monday is really the
only day that doesn`t look as favorable for thunderstorms...and
really the only dry period in the forecast until next weekend.
Any additional rainfall in those areas that have already received
a lot of rainfall could potentially be prone to more flooding.
This will need paying attention to over the course of next week,
in particular north central Kansas, which doesn`t need
anymore rainfall.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday evening)
Issued at 659 PM CDT Sun Sep 4 2016
The primary aviation concern will center around both strong low
level wind shear...as well as thunderstorms this evening through
tonight. Some of the thunderstorms in the area could be strong to
severe, but too early to say for sure if these more scattered
thunderstorms will directly impact the terminals or not. The most
likely time for thunderstorms will be between 9pm and 1am. The
low level wind shear will be rather strong through a majority of
the overnight hours.
&&
.GID Watches/Warnings/Advisories...
NE...None.
KS...None.
&&
$$
UPDATE...Wesely
SHORT TERM...Guerrero
LONG TERM...Guerrero
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Goodland KS
954 PM MDT SUN SEP 4 2016
.UPDATE...
Issued at 954 PM MDT Sun Sep 4 2016
Finalized update to cancel severe thunderstorm watch and flash
flood watch early. Storms have dissipated and are no longer
anticipated for the rest of the night.
&&
.SHORT TERM...(This evening through Monday)
Issued at 152 PM MDT Sun Sep 4 2016
Main concerns once again are thunderstorm coverage and heavy
rainfall/flash flooding/flooding concerns. Confidence is lowered
due to poor performance of models with yesterdays event, and some
model disagreement on how the evolution of tonight will pan out.
Air mass remains very moist and unstable. Area soundings this
morning showed precipitable water values near 1.5 inches.
A persistent instability/theta-e axis remains draped across the
center of the area from southwest to northeast. There one surface
boundary near the western end of the area and another draped over
the eastern end. PV/Satellite analysis show a decent shortwave
moving in from the southwest. At the same time all the models show
a right rear quadrant of the upper draped across the area. The
shortwave and jet lift move across the area from west/southwest to
the east through the evening.
Where the models are having trouble is where to put the
development. Some have it in the west and others in the east.
Considering that currently thunderstorms have developed and are
now moving into the western portion of the area, that looks to be
the way to go. Current trends favor the Rap and Hrrr.
So expect scattered thunderstorms producing heavy rainfall to move
across the area once again. Due to instability and shear in place,
severe looks likely as well. All in all a similar setup to the
last few days. So will keep the flash flood watch going with the
northeast portion of the area extremely susceptible to more
rainfall and flooding.
For Monday...with exception of jet lift, setup looks similar
tomorrow. Instability/moisture axis remains in the same place. So
more thunderstorms will be expected along with locally heavy
rainfall and possible severe.
.LONG TERM...(Monday night through Sunday)
Issued at 145 PM MDT Sun Sep 4 2016
Trough extends down out of western Canada all the say into the
southern portions of California Monday night into Tuesday morning
with high pressure over the southern Mississippi Valley. The surface
boundary draped from southwest to northeast across the CWA continues
to remain nearly stationary as we head through the day on Tuesday.
This will provide a focus for scattered thunderstorm activity
through the afternoon and into the evening once more with only
moderate instability and relatively weak upper level support
provided by passing shortwaves. A cold front will push through the
region later on Tuesday with slightly drier air behind it that will
linger into the middle to end of the week. Dry weather prevails
through Saturday with another, stronger cold front traversing the
region on Friday. Due to dry air in place preceding the front, PoPs
will be low across the CWA and should remain east of the region.
Afternoon high temperatures will be in the middle to upper 80s
Tuesday with a few 90 degree locations in the eastern portions of
the CWA. Slightly cooler highs prevail for Wednesday and Thursday
with highs in the middle 80s. Cold frontal passage will cool things
off a bit heading into Friday and Saturday with afternoon high
temperatures reaching the upper 70s to lower 80s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 520 PM MDT Sun Sep 4 2016
For KGLD...Mainly VFR conditions with scattered low/mid clouds.
VCTS 00z-03z...3sm br 10z-13z and VCSH 17z Monday onward. Winds SE
10-20kts becoming SSW by 03z Monday at 15-25kts. LLWS 220@50kts
from 03z-10z.
For KMCK... Mainly VFR conditions with scattered low/mid clouds.
VCTS 00z-03z...3sm br 10z-13z and VCSH 17z Monday onward. Winds
SSE 10-20kts w/ gusts to 25kts after 17z Monday. LLWS 200@50kts
from 03z-10z.
&&
.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...RRH
SHORT TERM...BULLER
LONG TERM...TL
AVIATION...JN
Area Forecast Discussion
National Weather Service Miami FL
911 PM EDT SUN SEP 4 2016
.AVIATION...
VFR conditions to prevail at all TAF sites. Models indicate
increase in moisture and large scale low level convergence over
the area by morning with gradually increasing shower chances.
Thunder also possible in the vicinity of the terminals by midday
Monday as daytime heating decreases stability.
&&
.PREV DISCUSSION... /issued 812 PM EDT SUN SEP 4 2016/
UPDATE...
A loop of water vapor imagery shows a distinct moisture front
dropping from north to south down the central Florida peninsula.
Small scale models continue this trend, but weaken the storm
activity as it moves into our CWA. Chance pops appears warranted
for areas around Lake Okeechobee through early tonight. Deeper
moisture will also filter in from the east late tonight, thus
increasing chance showers and thunderstorms along portions of the
east coast metro and inner coastal waters by early morning. With
an abundance of moisture and instability over the region Monday
afternoon into the evening, likely pops was maintained for nearly
all land areas. Otherwise, all other forecast variable appear on
track.
PREV DISCUSSION... /issued 441 PM EDT SUN SEP 4 2016/
SYNOPSIS...
Showers and thunderstorms will continue across the northern
interior and the Gulf coast regions this evening. Otherwise, dry
conditions should prevail for the east coast metro. Tomorrow, an
increase in moisture will ramp up shower and storm activity
area wide. As high pressure builds over the Atlantic by mid week,
a typical summer weather pattern should return to South Florida.
With a return to east to southeast flow, scattered
afternoon/evening convection will mainly affect the interior and
Gulf Coast.
DISCUSSION...
Water vapor imagery continues to show a band of elevated mid and
upper level moisture stretching to the south and southwest from
post Tropical Storm Hermine down toward the Gulf of Mexico.
However, over South Florida, dry/sinking air was observed. This
subsidence has acted to keep convection at bay this afternoon.
The 12Z KMFL sounding indicated a distinct dry layer around 700 mb
with a capping temperature inversion. By late afternoon, light
east winds in the lower levels will allow for a sea breeze
convergence over the western interior. Both the HRRR and HiRes WRF
generate storm activity over a general area stretching from
Naples to Lake Okeechobee into the evening. This has been
reflected well in the grids. By late tonight, the 12Z GFS
indicates a moisture surge pushing across the Atlantic waters and
towards the East Coast metro. Thus, pops will increase tonight
into tomorrow morning along the Atlantic coast. By Monday, deeper
moisture will advect into the region from both the north and east,
creating the potential for an active day of showers/storms area
wide. With the swath of moisture lingering over South Florida
through late Monday, the chance of showers and storms will
continue into the night. The main threats from the strongest
storms will be brief heavy rain, gusty winds, and frequent cloud
to ground lightning. Heat index on Monday will be peaking between
100-104 degrees, with highest values over southern Collier County.
Tuesday through the weekend, high pressure building over the
Atlantic will bring a return to the more typical summerlike pattern
to South Florida. Highest chances of afternoon storms will be
over the interior and Gulf Coast. During the nights, activity may
shift back towards the Atlantic coast.
Beaches: From Monday afternoon through Wednesday, models project a 3-
4 foot 11-12 second swell, generated by Hermine, to drop southward
down our Atlantic coastal waters. This scenario would create
elevated surf along the Atlantic beaches and an enhanced rip current
risk. Will continue to monitor NWPS output as the swell approaches.
MARINE...
As a high pressure ridge continues to build across the Atlantic
through late week, winds will turn light and easterly. There will
be a chance of showers and thunderstorms throughout the period. A
11-12 second swell, generated, by Hermine, will push south through
the Atlantic coastal waters Monday afternoon through early
Wednesday. Seas could peak around 3-5 feet east of Miami-
Dade/Collier counties and 5-7 feet in the coastal waters east of
Palm County. Conditions will begin to improve by late Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 79 90 77 87 / 20 60 40 50
Fort Lauderdale 80 89 78 88 / 30 60 40 50
Miami 80 90 78 89 / 30 60 40 50
Naples 77 91 75 89 / 40 60 30 60
&&
.MFL Watches/Warnings/Advisories...
FL...None.
AM...None.
GM...None.
&&
$$
SHORT TERM...27/JT
LONG TERM....27/JT
AVIATION...22/KS
Area Forecast Discussion
National Weather Service Blacksburg VA
752 PM EDT Sun Sep 4 2016
.SYNOPSIS...
High pressure will remain across the region tonight into midweek
as Hermine lingers off the mid-Atlantic coast over the next few
days. The area of high pressure will finally give way to a cold
front late in the week, which should bring the next chance for
showers and storms by next weekend.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 745 PM EDT Sunday...
No significant changes needed at this time. Last vestiges of light
rain showers associated with east-west oriented upper trough
rotating through the region on the back side of Hermine
dissipating and/or shifting south out of the RNK CWA. HRRR
indicates little to no activity from this point forward, so have
trended toward zero pops by 12Z Mon. Temperature/dewpoint
readings only needed minor changes.
As of 230 PM EDT Sunday...
An upper level low/short wave will track across eastern Virginia and
eastern North Carolina through this evening and merge with Post
tropical Hermine off the Mid Atlantic Coast Monday. Today`s short
wave is tracking south into very dry air and strong subsidence and
will bring an increase in clouds to the piedmont into this evening.
These clouds may produce a few sprinkles as the short wave passes to
the east. Behind this short wave, more dry air will enter the region
with abundant sunshine set for Monday. Heights increase Monday,
especially across the mountains, to have temperatures warm to or
just above seasonal normals (lower 80 west to mid 80s east).
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 230 pm EDT Sunday...
Ridging both surface and aloft will continue to gradually assert itself
from the southwest through the period between Hermine still off
Delmarva and the next upstream mid level trough. Dry north to northwest
flow combined with strong subsidence should keep overall pleasant
weather in place with temps and dewpoints slowly rising by the middle
of the week. Could also see some bands of clouds swing back across the
northern/eastern counties early on pending the proximity of Hermine but
too dry for any showers at this point. Otherwise mainly clear/sunny
with lows Monday night in the 50s to lower 60s and highs Tuesday
mid/upper 80s west to around 90 east. Should become a bit more humid
Tuesday night with lows mostly upper 50s to mid 60s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 200 PM EDT Sunday...
Strong upper ridging will remain in place midweek between the next
upstream shortwave trough approaching from the northwest and Hermine
that is still expected to be meandering off the mid-Atlantic coast.
This in combination with a dry north/northwest trajectory should keep
Wednesday into Thursday dry/warm before the flow aloft turns more zonal
later Thursday in response to flattening upper heights. Appears may see
just enough low level moisture return by Thursday evening to pop
isolated convection far western ridges, otherwise keeping it dry
both days with highs mid/upper 80s mountains to low 90s east.
Somewhat deeper moisture returns by late in the week as added subtle
height falls in conjunction with the flow turning more west/southwest
should erode ongoing subsidence in place. Although most of the
shortwave troffiness will shear by well to the north, looks like enough
to push a weak surface cold front south toward the area Friday before
it lifts back north by Saturday ahead of a bit stronger front that may
push into the area Sunday. Latest models also suggest that a pre-
frontal axis of deeper moisture will be over at least western sections
Friday/Saturday with perhaps another band of showers/storms along the
second front across the region on Sunday. Since still mostly diurnal
will continue overall chance pops mainly west through the period for
now. Otherwise return of humidity will make things quite muggy again
given highs 80s to lower 90s, except perhaps a bit cooler on Sunday
with the weak boundary around.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 745 PM EDT Sunday...
VFR conditions expected through the TAF valid period. East-west
oriented upper trough rotating around upper low over top of T.S.
Hermine will shift south of the region this evening. Associated
mid-level moisture and spotty showers will shift south as well and
dissipate. Ceilings have been and will continue to be VFR,
trending toward SKC by 06Z and beyond, likely to continue through
the remainder of the TAF valid period.
Visibility will also be VFR through the TAF valid period with the
exception of KLWB. Am concerned with calm winds and slightly
northeast drainage, that fog may develop here after 08Z. Not going
to take it down to 1/4SM FG at this time, but cannot completely
rule out this possibility. For now, will stop at 1SM as confidence
in fog development overall is not as high as usual given overall
dryness of air mass just off the surface.
Winds will continue to be NE east of the Blue Ridge to ESE west of
the Blue Ridge tonight on back side of Hermine with speeds
generally 5kts or less. With upper trough south to east of the
area and Hermine slightly further away Monday, expect a northwest
wind 5-7kts in most areas.
High confidence in cigs throughout the TAF valid period.
High confidence in vsbys throughout the TAF valid period, except
at KLWB, where confidence is medium in the 08Z-13Z time frame.
Medium to high confidence in wind speed/direction throughout the
TAF valid period.
Extended aviation discussion...
Generally VFR conditions expected through much of the extended
period as Hermine lingers off the mid-Atlantic coast for several
days into the mid part of the week. This will put our area in a
subsidence zone for several days. Relatively light winds and a
mainly clear sky should support the development of some patchy
late night/early morning fog in some of the deeper mountain
valleys. As low-level moisture continues to increase throughout
the week, expect late night/early morning fog/low clouds to be on
the increase. A cold front will arrive by the end of the week
bringing the next chance of showers and thunderstorms and any sub
VFR cigs.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH/RAB
NEAR TERM...RAB/RCS
SHORT TERM...JH
LONG TERM...JH
AVIATION...RAB/RCS
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Monday)
Issued at 314 PM CDT SUN SEP 4 2016
Overnight/early day convection has diminished with some lower
cloud building in as low level moisture increases. Water vapor
showing fast southwest flow over the Central Rockies and Northern
Plains with shortwave making quick progress into western Colorado
early this afternoon and scattered convection has developed ahead
of it. Breezy southerly winds helping push temps tin the lower and
middle 80s with dewpoints near 70.
Will likely see at least isolated activity persist in western
portions of the state through the afternoon. HRRR has been consistent
in more of a broken line of storms forming, but even it struggles to
maintain this activity into the CWA. Hard to completely rule out a
stray storm making it this far east but will keep a mention out.
Modest isentropic upglide resumes tonight over a 50kt south-
southwest low level jet with moisture in the low-mid levels not very
near saturation at any particular level. Again could see something
isolated develop mainly after midnight to just after sunrise but
don`t believe a mention is in order. The low level jet and high
dewpoints should keep lows in the lower 70s for the most part.
Stronger southerly winds, modest warm air advection from the
overnight, and less cloud should allow for Labor Day highs around
90.
.LONG TERM...(Monday Night through Sunday)
Issued at 314 PM CDT SUN SEP 4 2016
For the extended period, the general idea from the models is for
southwest flow aloft to transition to more of a of a progressive
pattern with shortwave troughs periodically moving through the
northern and central plains by the end of the work week and the
weekend. But before the transition, increasing moisture is progged
to occur along a surface trough/frontal boundary that sets up
just to the west and north of the forecast area through the middle
of the week. Models suggest that by Wednesday, a subtropical
fetch of moisture will get pulled into the area with PWs
approaching 2 inches. So the period from Wednesday through Friday
looks to be unsettled with some instability and reasonable flow
for storm organization.
For Monday night and Tuesday, the model consensus is for the
surface trough/front to remain to the northwest of the forecast
area with not much in the way of synoptic scale forcing
anticipated. With this in mind have kept a dry forecast until
Tuesday night when the forecast shows some small POPs across far
northern KS as the boundary gets a little closer. Temps are
forecast to be above normal. Persistent southerly flow and
increasing low level moisture should keep lows in the lower and
middle 70s. Highs Tuesday are expected to be around 90.
For Wednesday through Friday night, the forecast has a chance POP
for the reasons mentioned above. Models show an upper level trough
passing to the north of the forecast area Wednesday which doesn`t
really give much of a push to the surface boundary and allows it
to kind of stall out across northern KS and southern NEB. Large
scale forcing appears to remain subtle but there are signs for a
vort max to lift across the area Wednesday and Wednesday evening.
The stronger flow is expected to remain just north of the area so
odds for severe weather appear to be greater over northern KS
Wednesday where models increase deep layer shear. By Thursday the
boundary becomes less defined so a lack of focus for convective
development makes forecasting mesoscale details with confidence a
little tricky. Nevertheless the expected instability could lead
to scattered strong storms. By Friday, Models bring another upper
trough through the plains and a better push to the frontal
boundary. The addition of lift from the cold front with the
anticipated instability may provide the best opportunity for
precip.
The main uncertainty in the forecast is how strong the push to the
front on Friday will be. The ECMWF is quite a bit stronger with
the surface high behind the front and as a result is quicker to
move the boundary through the area and slower to develop return
flow on the back side of the surface ridge. The Canadian seems to
be in the GFS camp in terms of the magnitude of the surface ridge
behind the front. So the forecast is a compromise of the
solutions. Have a dry forecast for Saturday and Saturday night
with all guidance showing the boundary at least through the
forecast area by 12Z. Additionally have kept a slight chance POP
for Sunday from the model consensus thinking the ECMWF may be to
strong with the high pressure and there could be some warm air
advection back into the forecast area. Temps trend cooler for
Saturday and Sunday, but not nearly as cool as the ECMWF would
suggest.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 615 PM CDT SUN SEP 4 2016
VFR conditions are expected throughout the period. LLWS is
expected between after 03Z as the LLJ increase from the SSW near
45 knots. Winds will increase between 14-15Z with sustained 15-20
knots and gusts near 25+ knots.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...65
LONG TERM...Wolters
AVIATION...Baerg
Area Forecast Discussion
National Weather Service Billings MT
302 AM MDT MON SEP 5 2016
.SHORT TERM...valid for Tdy and Tue...
As the Pacific trough continues to move across the area this
morning, some light showers remain. However, the bulk of the
energy with this system has already moved through, and things
will begin to wind down through the morning. Before it does, a
couple of small waves of energy will move across mainly
southeastern Montana. This will keep some higher rain chances from
mainly Rosebud County eastward.
The satellite imagery is showing some drier air working into
behind the showers in Wyoming. Going into the afternoon, the GFS
and the HRRR are showing some clearing working into southern
Montana. Given this, have skies clearing out some. With the
reduced rainfall and cloudiness, have temperatures a little
warmer today.
Flow will remain northwesterly through the remainder of the
short-term. Tuesday will mostly be dry, with near seasonal
temperatures. Overnight into Wednesday, a weak wave will move
through the area bringing a slight chance for some precip to
southeastern Montana. Reimer
.LONG TERM...valid for Wed...Thu...Fri...Sat...Sun...
Models in good agreement for most of the extended period. They
indicate several short waves crossing over the region for the
latter half of the work week. However, moisture appears limited as
the best precipitable water values remain generally north and east
of our CWA. Flow aloft turns zonal Saturday leading to dry and
stable conditions. Extended range proggs then suggest a trough
will drop down into the Rockies at day 7 (Sunday) with some decent
moisture aboard leading to an increasing chance of precipitation.
Therefore, we have increased PoP`s in that time frame. BT
&&
.AVIATION...
Widespread showers and MVFR/IFR and possibly local LIFR Cigs
will continue across the TAF sites this morning. Expect CIGS to
improve to from west to east between 14Z and 19Z. BT
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Tue Wed Thu Fri Sat Sun
-------------------------------------------------------
BIL 063 044/073 051/071 049/073 048/070 048/079 053/075
5/T 21/U 11/B 11/B 11/U 10/U 12/W
LVM 060 037/071 043/069 043/071 040/069 041/077 045/073
5/T 21/U 21/N 11/B 11/U 11/U 12/W
HDN 066 043/075 048/074 046/075 045/072 044/080 048/076
4/T 21/U 11/B 11/B 11/B 10/U 02/W
MLS 063 045/073 052/072 049/074 049/070 048/079 053/077
7/T 20/U 22/W 12/T 21/N 10/U 02/W
4BQ 067 044/071 050/073 048/075 048/069 046/078 051/076
6/T 22/T 32/W 11/B 21/B 10/U 02/W
BHK 062 043/069 049/069 046/072 046/066 044/076 049/075
6/T 21/B 45/T 12/T 22/T 20/U 02/W
SHR 067 042/073 047/073 045/074 044/069 042/078 046/076
5/T 22/T 21/B 11/U 21/B 10/U 02/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Hastings NE
458 AM CDT MON SEP 5 2016
.SHORT TERM...(Today and tonight)
Issued at 422 AM CDT Mon Sep 5 2016
We continue with upper level southwest flow as a synoptic trough
over the Rocky Mountains/Great basin continues push out multiple
impulses from its base. A strong low-level jet axis essentially
bisects our CWA from southwest to northeast. The nose of the jet
could pose a slight chance of some small showers or
thundershowers, but should not amount to much. I considered taking
thunder out for early this morning before 7 am as MUCAPE is very
low and mid-level lapse rates are meager. However, with the modest
shear due to the strong low-level jet, I kept it in, especially
considering that we are still in the warm season. At the surface,
a very slowly moving cold front is just to the northwest of the
CWA and seems to be ever-so-slowly sagging south toward the CWA as
the front is oriented from southwest to northeast. Although areas
like Ord have become calm or near calm as the front approaches, I
kept mention of fog out as dewpoint depressions do not appear to
warrant this, and the fact that the HRRR keeps any fog development
west/northwest of the CWA.
Today should be dry as we experience subsidence behind the latest
impulse that came through. Another more significant vort max is on
the way from the southwest and by this evening, we could be in for
a round of showers/thunderstorms. We may be able to get some
surface based convection going near the front in the early
evening, especially for areas near Ord. We will probably have to
wait until after 7 pm to wait for the capping inversion to break.
With a veering wind profile and slow- moving if not stalled front,
we could not only be looking at some large hail and damaging wind
gusts if some sun breaks out, we could get an isolated tornado in
the early evening, so I mentioned this in the HWO.
As the vort max enters the plains, it will give us a rather
glancing blow. Essentially our northwest/north half of the CWA
stand the best chance at getting precipitation from this wave.
Severe parameters support severe mention, but frankly, severe
weather looks more probable to the north of the CWA as it looks
heading into the late evening and overnight.
For temperatures, I kicked them up a notch, especially for tonight
with the higher dewpoints and warm air advection in the southern
two-thirds of the CWA that should remain south of the stalled
front.
.LONG TERM...(Tuesday through Sunday)
Issued at 422 AM CDT Mon Sep 5 2016
Aloft: SW flow will be ovr the Cntrl Plains Tue with a trof over the
Wrn USA and a subtropical high over the E. The Wrn trof will
deamplify with its wavelength increasing. A broad trof will evolve
over the Nrn 1/2 of the CONUS by Wed with the flow arguably becoming
zonal. The subtropical high will be quashed.
Sidenote: TS Newton is currently off the coast of MX. It is fcst to
circulate poleward on the backside of the high...with its remnants
lifting into AZ Wed. It`s possible a piece of the mid-lvl energy
could make it into KS Thu.
Surface: At dawn Tue the slow-moving cool front will extend from CO
across Neb to Lake Superior. This front will remain quasi-stationary
thru Wed. In the meantime...another cool front will be making its
way thru the NW USA. This front will arrive here Thu night and merge
with it. This will nudge the front a little further SE. Another
front will arrive Thu night and this will force the combined front
far S and E of the region. Strong high pres will quickly slide into
the region Fri night-Sat...and then depart into the Ern USA Sun.
This fcst area will be in the warm sector Sun...with a strong cold
front plunging S into the Nrn USA.
Temps: warmer than normal Tue-Wed as long as clouds don`t hang
around unexpectedly. Then near normal or cooler than normal Thu-Sun.
A few daily details...
Tue: A few tstms afternoon/eve...and possibly into the overnight
hrs. Gut feeling is our PoPs are too high...mainly due to input from
the SREF. Deterministic model consensus puts the best QPF over Nrn
Neb...along and N of the front. Am inclined to believe it because it
has been so difficult to get rain over S-cntrl Neb the last 90 days.
I hope I`m wrong. The warm sector is likely to be capped. So the
primary way tstms build S to I-80 or Hwy 6 will be for a cold pool
to form and drop S into the warm sector.
Convergence/WAA along and N of the front will increase in the
evening as a 40-45 kt low-lvl jet develops.
Temps in the 80s with dwpts 66-70F will result in MLCAPE of at least
2000 J/kg. Initial storms will develop in the environment with 40-45
kts of deep layer shear. Svr tstms will be possible.
Wed: Probably dry...but can`t rule out an isolated tstm or two...
mainly along and E of hwy 281. For what it`s worth...18Z/00Z/06Z
model QPFs and highest SREF probs target areas SW-NE across KS and
then into Ern Neb for best chance of thunder...although it will be
more isolated with southward extent over KS.
Any storms that might develop could be svr with MLCAPE 1500-2000
J/kg and 40 kts of deep layer shear.
SEVERE: used Large Hail Parameter and Craven-Brooks SigSvr to
indicate potential for golf ball size hail in the HWO.
Thu: A couple tstms possible with shortening wavelengths/approaching
trof and the RRQ of a strong 120 kts upr-lvl jet. However...model
QPFs are far from impressive.
Fri: removed thunder from the fcst as EC indicates stability as the
low-lvl moist axis gets shoved S of the fcst area.
Sat-Sun: Dry and wonderfully comfortable...especially Sat with dwpts
upr 40s-lwr 50s.
&&
.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Monday night)
Issued at 1255 AM CDT Mon Sep 5 2016
The main issue will be low-level wind shear overnight into early
Monday morning. The low-level jet is strong enough to include
shear in the forecast, despite the fact that surface wind will be
relatively strong.
&&
.GID Watches/Warnings/Advisories...
NE...None.
KS...None.
&&
$$
SHORT TERM...Heinlein
LONG TERM...Kelley
AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Melbourne FL
330 AM EDT MON SEP 5 2016
...High Risk for Dangerous Rip Currents Developing Today...
.DISCUSSION...
TODAY/TONIGHT...(LABOR DAY) Several locations received generous
rains of 2-4 inches yesterday as advertised in the presence of
high PWAT air from the trailing moisture band and weak sfc trough
stretching over the FL Peninsula extending from Hermine which was
located well to the north. With the assistance of a weak impulse
aloft, local precipitation was able to persist well into the
overnight. There has been a general diminishing of activity from
MLB southward, but maritime convection was being invigorated from
increasing NE flow that will work its way down the coast from JAX
courtesy of high pressure pushing south down the U.S. Seaboard.
The result is a ~15KT NE wind surge today which will be
instrumental in bumping the banded moisture/trough and associated
rain chances to South FL by tonight advecting in deep layer
drying. Rain chances greater south forecast area trending toward
Lake Okeechobee as day progresses. Max Temps U80s to near 90. Min
Temps L/M70s.
The increasing onshore flow along with arriving long period
swells will promote a high risk for rip currents at area beaches,
even as overall sky conditions improve behind the push. A concern
to beach-goers this Labor Day from larger volumes of water piling
ashore and an increased number/intensity of rips especially during
the times of the outgoing tide.
TUE...A much drier airmass will be across the region to start
Tuesday with GFS indicating PW values as low as an inch. However
models indicate a gradual increase in moisture in the slightly
elevated low level northeast flow through the day, which may lead to
some showers developing over the waters and reaching the coast later
in the day/evening. Still rain chances look to be quite low with
MAV/MET guidance keeping any mentionable PoPs south of Orlando, and
even then rain chances are no greater than 20 percent. For now will
maintain a slight chance for showers/storms over the Treasure Coast
and Okeechobee County, but looks like much of the area should remain
dry.
WED-SUN...Onshore flow will persist through the extended as West
Atlantic high pressure builds back in, with ridge axis remaining
north of the area. E/SE flow will continue to gradually increase
moisture and rain chances across the region, with PoPs reaching back
up to 40-50 percent by the weekend. Greatest coverage of afternoon
convection will be over the interior and a lingering chance of
onshore moving showers/isolated storms will persist along the coast
in the overnight and morning hours. Temperatures remain near normal
through the period.
&&
.AVIATION...Recent assortment of variable ceilings and vsbys as
debris -RA and -SHRA gradually diminishes near KMLB/KVRB but NE
wind surge being felt north of Cape Canaveral with onshore moving
SHRA prompting VCSH for KDAB/KSFB. Plenty of residual moisture
available for patchy BR to reduce vsbys and introduce tempo IFR
ceilings for inland sites KLEE/KSFB during periods of
light/variable winds. Wind surge will win out and improve
conditions after 12Z trending from KDAB south and southwest but
not before VCTS temporarily enters the forecast window for a few
hours 16-20Z ahead of clearing line of NE winds G20KT during the
afternoon.
&&
.MARINE...
TODAY/TONIGHT...Cautionary conditions will develop over the
waters today continuing overnight as a NE wind surge of 15KT moves
in behind a weak sfc trough over Central FL being pushed toward
the South Peninsula. Seas will build to 3-5FT nearshore today and
up to 6FT offshore. This will occur in the presence of long period
2-3FT swells of 10-12 seconds. Deteriorating boating conditions
will work southward from Flagler Beach eventually to Jupiter
Inlet, with gusty winds an additional concern near the coast,
intracoastals, and within inlets. GFS model has winds just a
little stronger than HRRR model so Advisory conditions not out of
the question, especially in the Gulf Stream.
TUE-FRI...High pressure will build back in north of the area with a
persistent onshore flow through the week. Wind speeds up to 10-15
knots Tuesday-Wednesday forecast to decrease slightly to 5-10 knots
into late week. Seas up to 6 feet offshore Tuesday, mainly in a long
period swell will gradually decrease, becoming 2-3 feet Thursday and
Friday.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 86 72 87 73 / 30 0 10 10
MCO 88 73 89 73 / 30 10 10 10
MLB 87 75 87 75 / 30 10 10 20
VRB 87 75 88 74 / 30 20 20 20
LEE 89 72 90 73 / 30 0 10 0
SFB 88 72 90 73 / 30 0 10 10
ORL 88 73 89 73 / 30 10 10 10
FPR 88 75 87 73 / 40 20 20 20
&&
.MLB Watches/Warnings/Advisories...
FL...None.
AM...None.
&&
$$
SHORT TERM...DS
LONG TERM....DW
Area Forecast Discussion
National Weather Service Marquette MI
515 AM EDT MON SEP 5 2016
.SHORT TERM...(Today and tonight)
Issued at 514 AM EDT MON SEP 5 2016
WV imagery and RAP analysis indicated a broad area of mid/upper
level sw flow through the plains to the wrn Great Lakes between a
trough over the wrn CONUS and a ridge from the Gulf of Mexico
through the ern Great Lakes. At the surface, increasing southerly
flow prevailed into Upper Michigan between high pres over the ern
Great Lakes and a trough from the ern Dakotas to nw Ontario. A
shortwave trough into wrn MN along with strong inflow of moisture
supported an MCS over much of MN and nw WI into nw IA. The lead area
of 850-700 mb theta-e advection was bringing shra/tsra into wrn Lake
Superior and wrn Upper Michigan.
Today, Radar and satellite trends along with short term high res
models suggest that the MCS will lift to the northeast with the
greatest pcpn amounts/coverage over the wrn cwa this morning. After
the pcpn moves through and weakens, expect a lull in the pcpn
by late this afternoon into this evening with subsidence in the wake
of the shrtwv/MCV. Expect enough sunshine through the thinning
convective debris this afternoon to boost high temps into the lower
80s, except over the ern cwa downwind from ssw flow off of Lake
Michigan where max readings will remain in the mid to upper 70s.
Tonight, expect another shrtwv to emerge from the plains. However,
confidence in the timing/location is low given the impact of the
ongoing large area of convection. Much of the convection may again
focus on wrn and nrn Lake Superior. Nevertheless, with the frontal
boundary just to the west, and MUCAPE values into the 1000-1500 J/Kg
range, likely shra/tsra pops were mentioned over the far west with
chance over the rest of the cwa. With effective shear values into
the 30-40 knot range, some stronger storms and isold svr may be
possible. With PWAT values to around 1.75 inch, the main hazard
will more likely be heavy rain.
.LONG TERM...(Tuesday through Sunday)
Issued at 417 AM EDT MON SEP 5 2016
Much more active weather is on tap for the upcoming week with
the overall upper pattern transitioning from the amplified western
troughing/eastern ridging early this week into a more zonal pattern
across the CONUS by next weekend. Until the pattern shift occurs...SW
upper flow will remain across the Upper Lakes for much of the week
allowing a series of shortwaves to move across the area and trigger
periods of enhanced showers and thunderstorms. The timing of these
shortwaves remains difficult for models to resolve. While it won`t
rain the entire week, current model consensus is keying on the
wettest periods being late Tuesday, Wednesday afternoon into Thursday
morning, and Friday night into early Saturday. Ingredients will be in
place for some locally heavy rain especially through midweek. These
ingredients include a slow- moving surface cold front paralleling the
upper flow as it moves through the Upper Great Lakes region,
shortwaves and assoc sfc waves lifting NE across the area and frontal
boundary in a broad SW upper flow, and PWs increasing to around 2
inches. As a result, much of the U.P. remains highlighted in the NCEP
Hazardous Outlook for a heavy rain threat Wed into Thu. WPC QPF
graphics indicate that most of the U.P. should see rain totals in the
1-3 inch range through the upcoming week with the heaviest rain
potential over the south central fcst area.
Day 2 SPC Convective Outlook has much of the western half interior
and south central portions of Upper Mi in a marginal risk for severe
weather. Of course, much of severe threat will be dependent on cloud
cover, but if we could see some morning sunshine to help with
destabilization along the incoming frontal boundary, marginal risk
seems reasonable as NAM model soundings show mid-level cap eroding
with MLCAPEs rising to near 2000 j/kg range by Tue afternoon and 0-6
Km bulk shear values fm 30-40 kts. Will include a mention of
isolated severe thunderstorms Tue afternoon/early evening in the HWO
over western interior and south central.
The driest days this week look like Thursday and then again Saturday
afternoon through next Sunday.
Despite significant cloud cover, temperatures will run above normal
at least through midweek...especially overnight lows with high
minimum temp records in jeopardy Tuesday and Wednesday. Dewpoints in
the mid to upper 60s into Thursday will make it feel quite humid. A
front moving through by the weekend should then cool temperatures
back to normal with lower humidity.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 121 AM EDT MON SEP 5 2016
As a steady SW flow draws moister air into the Upr Great Lks, some
-shra and perhaps a TS wl impact IWD and CMX, mainly in the 09Z-18Z
time frame. But the near sfc air wl remain dry enuf to allow for VFR
conditions to predominate at all 3 TAF locations. Best chc for lower
MVFR conditions wl be at IWD, where the showers chcs are greatest.
Maintained fcst of LLWS at IWD thru sunrise with the LLJ above a
nocturnal radiation invrn. Expect some gusty winds by Mon aftn at
the more exposed SAW and IWD locations as daytime heating mixes out
these winds. More LLWS is likely tngt at SAW under the sharper pres
gradient ahead of slowly aprchg cold fnt. There could be some
showers/TS at mainly IWD and CMX by late this evng ahead of this
fnt, but confidence is too lo to include in the fcst attm.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 514 AM EDT MON SEP 5 2016
Winds through the middle of next week are expected to remain mainly
at 20 kts or less. The only exceptions would be today with south to
southwest winds up to 25 knots in gusts over eastern Lake Superior
ahead of an approaching low pressure trough and again Thursday as a
low deepens to the northeast of Lake Superior.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Voss
AVIATION...KC
MARINE...JLB
Area Forecast Discussion
National Weather Service Billings MT
920 AM MDT MON SEP 5 2016
.UPDATE...
Water vapor imagery shows upper low lifting to north central MT,
with dry slot surging into southeast MT. Pcpn has tapered off
significantly across our south over the past couple hours, and
this trend will continue thru the remainder of the morning as
ascent lifts north and out of our cwa, though we are still seeing
impacts from low clouds and areas of upslope flow/drizzle. Have
lowered pops thru 18z per current radar trends. PV will remain
over south central MT, and with abundant moisture and low
convective temps would expect rapid development of clouds and some
light showers as skies become scattered to broken. This diurnal
development will diminish quickly this evening. Next issue to
consider is fog potential tonight as sfc high settles in and winds
become generally light. Not expecting much boundary layer drying
today, and low temps tonight should fall thru our afternoon dew
pts, so looks like a reasonable chance of fog across much of our
cwa tonight. Latest HRRR runs are starting to suggest fog as well.
Have added patchy fog 06z- 15z Tuesday. JKL
&&
.SHORT TERM...valid for Tdy and Tue...
As the Pacific trough continues to move across the area this
morning, some light showers remain. However, the bulk of the
energy with this system has already moved through, and things
will begin to wind down through the morning. Before it does, a
couple of small waves of energy will move across mainly
southeastern Montana. This will keep some higher rain chances from
mainly Rosebud County eastward.
The satellite imagery is showing some drier air working into
behind the showers in Wyoming. Going into the afternoon, the GFS
and the HRRR are showing some clearing working into southern
Montana. Given this, have skies clearing out some. With the
reduced rainfall and cloudiness, have temperatures a little
warmer today.
Flow will remain northwesterly through the remainder of the
short-term. Tuesday will mostly be dry, with near seasonal
temperatures. Overnight into Wednesday, a weak wave will move
through the area bringing a slight chance for some precip to
southeastern Montana. Reimer
.LONG TERM...valid for Wed...Thu...Fri...Sat...Sun...
Models in good agreement for most of the extended period. They
indicate several short waves crossing over the region for the
latter half of the work week. However, moisture appears limited as
the best precipitable water values remain generally north and east
of our CWA. Flow aloft turns zonal Saturday leading to dry and
stable conditions. Extended range proggs then suggest a trough
will drop down into the Rockies at day 7 (Sunday) with some decent
moisture aboard leading to an increasing chance of precipitation.
Therefore, we have increased PoP`s in that time frame. BT
&&
.AVIATION...
MVFR/IFR conditions with patchy drizzle and fog will gradually
lift N of the area this afternoon. Expect VFR this afternoon with
isolated to scattered showers and possibly a thunderstorm. MVFR
conditions are possible with the precipitation. Isolated showers
or thunderstorms will continue this evening. Precipitation will
end late this evening, but patchy fog and stratus will form across
much of the area, reducing visibilities and ceilings. Expect areas
of mountain obscuration through this evening. Arthur
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Tue Wed Thu Fri Sat Sun
-------------------------------------------------------
BIL 063 044/073 051/071 049/073 048/070 048/079 053/075
3/T 21/U 11/B 11/B 11/U 10/U 12/W
LVM 060 037/071 043/069 043/071 040/069 041/077 045/073
5/T 31/U 21/N 11/B 11/U 11/U 12/W
HDN 066 043/075 048/074 046/075 045/072 044/080 048/076
3/T 21/U 11/B 11/B 11/B 10/U 02/W
MLS 063 045/073 052/072 049/074 049/070 048/079 053/077
5/W 20/U 22/W 12/T 21/N 10/U 02/W
4BQ 067 044/071 050/073 048/075 048/069 046/078 051/076
2/T 22/T 32/W 11/B 21/B 10/U 02/W
BHK 062 043/069 049/069 046/072 046/066 044/076 049/075
6/T 21/B 45/T 12/T 22/T 20/U 02/W
SHR 067 042/073 047/073 045/074 044/069 042/078 046/076
3/T 22/T 21/B 11/U 21/B 10/U 02/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Hastings NE
627 AM CDT MON SEP 5 2016
.SHORT TERM...(Today and tonight)
Issued at 422 AM CDT Mon Sep 5 2016
We continue with upper level southwest flow as a synoptic trough
over the Rocky Mountains/Great basin continues push out multiple
impulses from its base. A strong low-level jet axis essentially
bisects our CWA from southwest to northeast. The nose of the jet
could pose a slight chance of some small showers or
thundershowers, but should not amount to much. I considered taking
thunder out for early this morning before 7 am as MUCAPE is very
low and mid-level lapse rates are meager. However, with the modest
shear due to the strong low-level jet, I kept it in, especially
considering that we are still in the warm season. At the surface,
a very slowly moving cold front is just to the northwest of the
CWA and seems to be ever-so-slowly sagging south toward the CWA as
the front is oriented from southwest to northeast. Although areas
like Ord have become calm or near calm as the front approaches, I
kept mention of fog out as dewpoint depressions do not appear to
warrant this, and the fact that the HRRR keeps any fog development
west/northwest of the CWA.
Today should be dry as we experience subsidence behind the latest
impulse that came through. Another more significant vort max is on
the way from the southwest and by this evening, we could be in for
a round of showers/thunderstorms. We may be able to get some
surface based convection going near the front in the early
evening, especially for areas near Ord. We will probably have to
wait until after 7 pm to wait for the capping inversion to break.
With a veering wind profile and slow- moving if not stalled front,
we could not only be looking at some large hail and damaging wind
gusts if some sun breaks out, we could get an isolated tornado in
the early evening, so I mentioned this in the HWO.
As the vort max enters the plains, it will give us a rather
glancing blow. Essentially our northwest/north half of the CWA
stand the best chance at getting precipitation from this wave.
Severe parameters support severe mention, but frankly, severe
weather looks more probable to the north of the CWA as it looks
heading into the late evening and overnight.
For temperatures, I kicked them up a notch, especially for tonight
with the higher dewpoints and warm air advection in the southern
two-thirds of the CWA that should remain south of the stalled
front.
.LONG TERM...(Tuesday through Sunday)
Issued at 422 AM CDT Mon Sep 5 2016
Aloft: SW flow will be ovr the Cntrl Plains Tue with a trof over
the Wrn USA and a subtropical high over the E. The Wrn trof will
deamplify with its wavelength increasing. A broad trof will evolve
over the Nrn 1/2 of the CONUS by Wed with the flow arguably
becoming zonal. The subtropical high will be quashed.
Sidenote: TS Newton is currently off the coast of MX. It is fcst
to circulate poleward on the backside of the high...with its
remnants lifting into AZ Wed. It`s possible a piece of the mid-lvl
energy could make it into KS Thu.
Surface: At dawn Tue the slow-moving cool front will extend from
CO across Neb to Lake Superior. This front will remain quasi-
stationary thru Wed. In the meantime...another cool front will be
making its way thru the NW USA. This front will arrive here Thu
night and merge with it. This will nudge the front a little
further SE. Another front will arrive Thu night and this will
force the combined front far S and E of the region. Strong high
pres will quickly slide into the region Fri night-Sat...and then
depart into the Ern USA Sun. This fcst area will be in the warm
sector Sun...with a strong cold front plunging S into the Nrn USA.
Temps: warmer than normal Tue-Wed as long as clouds don`t hang
around unexpectedly. Then near normal or cooler than normal Thu-
Sun.
A few daily details...
Tue: A few tstms afternoon/eve...and possibly into the overnight
hrs. Gut feeling is our PoPs are too high...mainly due to input
from the SREF. Deterministic model consensus puts the best QPF
over Nrn Neb...along and N of the front. Am inclined to believe it
because it has been so difficult to get rain over S-cntrl Neb the
last 90 days. I hope I`m wrong. The warm sector is likely to be
capped. So the primary way tstms build S to I-80 or Hwy 6 will be
for a cold pool to form and drop S into the warm sector.
Convergence/WAA along and N of the front will increase in the
evening as a 40-45 kt low-lvl jet develops.
Temps in the 80s with dwpts 66-70F will result in MLCAPE of at
least 2000 J/kg. Initial storms will develop in the environment
with 40-45 kts of deep layer shear. Svr tstms will be possible.
Wed: Probably dry...but can`t rule out an isolated tstm or two...
mainly along and E of hwy 281. For what it`s worth...18Z/00Z/06Z
model QPFs and highest SREF probs target areas SW-NE across KS and
then into Ern Neb for best chance of thunder...although it will be
more isolated with southward extent over KS.
Any storms that might develop could be svr with MLCAPE 1500-2000
J/kg and 40 kts of deep layer shear.
SEVERE: used Large Hail Parameter and Craven-Brooks SigSvr to
indicate potential for golf ball size hail in the HWO.
Thu: A couple tstms possible with shortening
wavelengths/approaching trof and the RRQ of a strong 120 kts upr-
lvl jet. However...model QPFs are far from impressive.
Fri: removed thunder from the fcst as EC indicates stability as
the low-lvl moist axis gets shoved S of the fcst area.
Sat-Sun: Dry and wonderfully comfortable...especially Sat with
dwpts upr 40s-lwr 50s.
&&
.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Tuesday)
Issued at 627 AM CDT Mon Sep 5 2016
Significant Wx: LLWS now until 14Z and then again tonight.
Today: LLWS end by 14Z. VFR with just a few altocu 10-13K this
morning. Then a few CU develop around 3500 ft this afternoon. S
winds will increase to around 20 kts with G30 kts. Confidence:
High
Tonight: VFR. LLWS redevelops. There is a very low probability of
an IFR tstm and G40KT...but left it out for now due to high
uncertainty. S winds decrease but remain gusty at times.
Confidence: Medium
&&
.GID Watches/Warnings/Advisories...
NE...None.
KS...None.
&&
$$
SHORT TERM...Heinlein
LONG TERM...Kelley
AVIATION...Kelley
Area Forecast Discussion
National Weather Service Lincoln IL
934 AM CDT MON SEP 5 2016
.UPDATE...
Issued at 934 AM CDT Mon Sep 5 2016
Main forecast update was to add some 20% PoP`s across areas east
of I-55 this morning. Radar imagery the last couple hours has been
showing some isolated showers tracking northeast amongst the
scattered cumulus in this region, most numerous south of I-70.
06Z NAM-Nest model was the only one that seems to pick up on
this, and indicates the shower threat should be more across
Indiana by midday. Some light showers are starting to show up as
far west as Carlinville, but cumulus field and latest RAP cu-rule
guidance showing little in the way of cumulus west of I-55, so
am not expecting much further westward development. Temperatures
are on track and only required some minor tweaks.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 323 AM CDT Mon Sep 5 2016
Ridge of high pressure that provided cool/dry weather to central
Illinois over the past couple of days has shifted eastward into the
Appalachians. As a result, winds are beginning to veer to a more
southerly direction. This will help bring warmer and more humid
conditions back into the area today. Given increasing low-level
moisture and surface dewpoints climbing into the upper 60s and lower
70s, diurnal cloud cover will be more robust than in previous days.
In fact, NAM Cu-rule suggests SCT-BKN clouds east of I-55 this
afternoon. Have adjusted sky cover to go with partly sunny
conditions across the eastern half of the KILX CWA accordingly.
Despite additional cloud cover, southerly winds will help boost
high temperatures into the middle to upper 80s. Diurnal clouds
will fade away toward sunset, leading to mostly clear conditions
tonight. Overnight low temperatures will range from the middle
to upper 60s in the Wabash River Valley...to the lower 70s west of
I-55.
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 323 AM CDT Mon Sep 5 2016
Blocking pattern will remain in place across the central/eastern
CONUS through mid-week, as remains of Hurricane Hermine meander off
the Mid-Atlantic coast. Upper ridge will build over the Midwest,
with both the GFS and ECMWF showing 594dm 500mb heights over central
Illinois by Tuesday and Wednesday. With surface high sliding off to
the east and southerly winds developing across the area, a period of
very warm and increasingly humid conditions is expected. Based on
850mb temps progged to climb to around 20C, it appears Tuesday and
Wednesday will be the warmest days of the forecast period, with high
temperatures both days reaching the lower 90s. While a few models
(particularly the GFS) suggest widely scattered convection within
the warmer airmass, main baroclinic zone and strongest forcing will
stay well to the N/NW until Wednesday night. As a result, have gone
with a warm/dry forecast through Wednesday.
After that, upper blocking pattern will break down as remains of
Hermine get shunted northeastward and prevailing Midwest ridge
flattens. 00z Sep 5 models are in relatively good agreement, with
slow-moving cold front over the central/northern Plains pushing into
the area Wednesday night. Given deep-layer moisture characterized
by precipitable water values in excess of 2 inches and increasing
upper support, have opted to go with high chance to likely PoPs
mainly after midnight. The front will stall across central
Illinois during the day Thursday as it becomes parallel to the
upper flow, resulting in continued chance PoPs. All models then
show a wave developing along the boundary, causing the front to
lift back northward Thursday night into Friday. Due to enhanced
synoptic lift with this feature, have introduced likely PoPs
across the W/SW CWA Thursday night, then everywhere north of the
I-70 corridor on Friday.
A stronger short-wave trough will dig southeastward into the region
for the upcoming weekend, eventually pushing the persistent frontal
boundary well to the east and south. Latest models have sped up the
wave, with the ECMWF now showing the front along the I-70 corridor
as early as 12z Sat. GFS remains slightly slower, but still shows
the boundary clearing the area by early afternoon. At this time,
will hold on to chance PoPs east of I-55 through the day Saturday,
followed by a return to cooler/drier weather Saturday night and
Sunday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 644 AM CDT Mon Sep 5 2016
VFR conditions expected across the central IL terminals through
the 12Z TAF period. Scattered cumulus around 5000 ft AGL across
the area this morning expected to clear at least from KSPI-KPIA
westward late in the morning...but will be replaced by diurnal
cumulus development by 17Z across the area through 00Z. Winds SE
5-10 kts in the morning becoming S 10-15 kts with gusts to around
20 kts after 17Z. Winds decreasing to under 10 kts after 00Z.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...Geelhart
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Onton
Area Forecast Discussion
National Weather Service Marquette MI
743 AM EDT MON SEP 5 2016
.SHORT TERM...(Today and tonight)
Issued at 514 AM EDT MON SEP 5 2016
WV imagery and RAP analysis indicated a broad area of mid/upper
level sw flow through the plains to the wrn Great Lakes between a
trough over the wrn CONUS and a ridge from the Gulf of Mexico
through the ern Great Lakes. At the surface, increasing southerly
flow prevailed into Upper Michigan between high pres over the ern
Great Lakes and a trough from the ern Dakotas to nw Ontario. A
shortwave trough into wrn MN along with strong inflow of moisture
supported an MCS over much of MN and nw WI into nw IA. The lead area
of 850-700 mb theta-e advection was bringing shra/tsra into wrn Lake
Superior and wrn Upper Michigan.
Today, Radar and satellite trends along with short term high res
models suggest that the MCS will lift to the northeast with the
greatest pcpn amounts/coverage over the wrn cwa this morning. After
the pcpn moves through and weakens, expect a lull in the pcpn
by late this afternoon into this evening with subsidence in the wake
of the shrtwv/MCV. Expect enough sunshine through the thinning
convective debris this afternoon to boost high temps into the lower
80s, except over the ern cwa downwind from ssw flow off of Lake
Michigan where max readings will remain in the mid to upper 70s.
Tonight, expect another shrtwv to emerge from the plains. However,
confidence in the timing/location is low given the impact of the
ongoing large area of convection. Much of the convection may again
focus on wrn and nrn Lake Superior. Nevertheless, with the frontal
boundary just to the west, and MUCAPE values into the 1000-1500 J/Kg
range, likely shra/tsra pops were mentioned over the far west with
chance over the rest of the cwa. With effective shear values into
the 30-40 knot range, some stronger storms and isold svr may be
possible. With PWAT values to around 1.75 inch, the main hazard
will more likely be heavy rain.
.LONG TERM...(Tuesday through Sunday)
Issued at 417 AM EDT MON SEP 5 2016
Much more active weather is on tap for the upcoming week with
the overall upper pattern transitioning from the amplified western
troughing/eastern ridging early this week into a more zonal pattern
across the CONUS by next weekend. Until the pattern shift occurs...SW
upper flow will remain across the Upper Lakes for much of the week
allowing a series of shortwaves to move across the area and trigger
periods of enhanced showers and thunderstorms. The timing of these
shortwaves remains difficult for models to resolve. While it won`t
rain the entire week, current model consensus is keying on the
wettest periods being late Tuesday, Wednesday afternoon into Thursday
morning, and Friday night into early Saturday. Ingredients will be in
place for some locally heavy rain especially through midweek. These
ingredients include a slow- moving surface cold front paralleling the
upper flow as it moves through the Upper Great Lakes region,
shortwaves and assoc sfc waves lifting NE across the area and frontal
boundary in a broad SW upper flow, and PWs increasing to around 2
inches. As a result, much of the U.P. remains highlighted in the NCEP
Hazardous Outlook for a heavy rain threat Wed into Thu. WPC QPF
graphics indicate that most of the U.P. should see rain totals in the
1-3 inch range through the upcoming week with the heaviest rain
potential over the south central fcst area.
Day 2 SPC Convective Outlook has much of the western half interior
and south central portions of Upper Mi in a marginal risk for severe
weather. Of course, much of severe threat will be dependent on cloud
cover, but if we could see some morning sunshine to help with
destabilization along the incoming frontal boundary, marginal risk
seems reasonable as NAM model soundings show mid-level cap eroding
with MLCAPEs rising to near 2000 j/kg range by Tue afternoon and 0-6
Km bulk shear values fm 30-40 kts. Will include a mention of
isolated severe thunderstorms Tue afternoon/early evening in the HWO
over western interior and south central.
The driest days this week look like Thursday and then again Saturday
afternoon through next Sunday.
Despite significant cloud cover, temperatures will run above normal
at least through midweek...especially overnight lows with high
minimum temp records in jeopardy Tuesday and Wednesday. Dewpoints in
the mid to upper 60s into Thursday will make it feel quite humid. A
front moving through by the weekend should then cool temperatures
back to normal with lower humidity.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 742 AM EDT MON SEP 5 2016
As a steady SW flow draws moister air into the region and a
disturbance lifts through the area shra/tsra will imapct IWD and CMX
this morning. But the near sfc air wl remain dry enough to allow for
mainly VFR conditions. The best chance for MVFR conditions will be
at IWD with the most persistent rain. More LLWS is likely tonight
under the sharper pres gradient ahead of slowly approaching cold
front. There could be some showers/TS at mainly IWD and CMX by late
this evening ahead of this front, but confidence is too low to
include in the fcst attm.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 514 AM EDT MON SEP 5 2016
Winds through the middle of next week are expected to remain mainly
at 20 kts or less. The only exceptions would be today with south to
southwest winds up to 25 knots in gusts over eastern Lake Superior
ahead of an approaching low pressure trough and again Thursday as a
low deepens to the northeast of Lake Superior.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Voss
AVIATION...JLB
MARINE...JLB
Area Forecast Discussion
National Weather Service Billings MT
300 PM MDT MON SEP 5 2016
.SHORT TERM...valid for Tue and Wed...
Water vapor imagery shows upper trof axis still over the northern
Rockies, with stronger shortwave having departed to our northeast
but lingering PV over south central MT. Convective temps are
rather low and we are already seeing scattered showers develop
west of KBIL and tracking east. There is also an area of
thunderstorms in southeast Carter County extending to near Devils
tower that is along region of strong low level frontogenesis. This
stronger activity should push east of our cwa over the next couple
hours as front does likewise. Overall, expect isolated to
scattered showers and a few low-topped t-storms between now and
sunset courtesy of the cyclonic flow aloft and daytime heating,
along with abundant residual boundary layer moisture. Dry
conditions will prevail late tonight.
Main forecast concern in the short term is fog potential late
tonight into Tuesday morning. Looks like a good setup for fog as
sfc ridge settles in producing light winds and clearing skies. Low
temps tonight should fall below current dew pts, by several
degrees in some places, and HRRR has trended consistently towards
fog across parts of the cwa after midnight. SO, with confidence
have added patchy fog from 06-15z. A Billings upslope fog event is
possible.
We will see some theta-e return into southeast MT on Tuesday with
LIs near -2c by late in the day. Could see a shower/t-storm pop by
late afternoon but better chance of this will be thru the night as
next Pacific shortwave moves thru the area. Will keep isolated
pops for our west-central parts Tuesday night but much better
potential for pcpn will be east of sfc trof, i.e. Rosebud County
eastward, with activity extending into Wednesday morning before
energy shifts east.
We will see a gusty W-NW wind with good mixing in post-frontal
regime across the lower elevations on Wednesday. Gusts should
reach 25-35 mph. Drier air will advect into our cwa behind early
Wednesday shortwave, so will keep only isold pops for the high
terrain.
After a chilly night tonight with lows in the upper 30s to mid 40s
(dewpts are too high for a serious risk of a freeze), temps will
turn warmer the next two days with highs back to the upper 60s to
mid 70s across the lower elevations. This will be closer to normal
but still a few degrees on the cool side for early September.
JKL
.LONG TERM...valid for Thu...Fri...Sat...Sun...Mon...
Good agreement in the global models continues through the
extended period. Northwesterly upper level flow will keep
temperatures seasonably cool with a few showers as a weak
disturbance crosses the region Thursday afternoon into Friday.
Not expecting widespread precipitation with this disturbance, but
the better chance will be to the east and northeast of Billings,
and closer to the upper level low passing over northeastern
Montana. Expect a breezy Friday across the forecast area as the
disturbance quickly passes.
Conditions turn drier and warmer over the weekend with
temperatures nearing 80 on Saturday as a ridge of high pressure
moves overhead. By the end of the weekend, models are beginning to
agree on the next cool down. Global models suggest an upper level
low diving south across the forecast area. With good agreement in
this system being a cooler one, would not be surprised to another
chance for high elevation snow, so lowered temps and increased
precip chances for the higher terrain and nearby foothills. Dobbs.
&&
.AVIATION...
MVFR conditions will gradually lift to VFR this afternoon.
Isolated to scattered showers and a few thunderstorms will
decrease this evening. MVFR conditions are possible with the
precipitation. Areas of fog will develop late this evening
producing MVFR/IFR conditions. Areas of stratus are likely as
well, especially E of KBIL. The stratus will produce IFR to LIFR
conditions E of KBIL. VFR will return to much of the area after
15Z Tuesday. Lower conditions may linger longer over KMLS. Expect
areas of mountain obscuration through this evening. Arthur
&&
.PRELIMINARY POINT TEMP/POPS...
Tue Wed Thu Fri Sat Sun Mon
-----------------------------------------------------------
BIL 044/073 052/072 049/073 048/070 048/079 053/074 045/058
20/U 21/N 11/B 11/U 10/U 12/W 33/W
LVM 037/071 043/070 043/070 041/068 042/077 045/073 039/053
21/U 21/N 11/B 21/U 11/U 13/W 33/W
HDN 042/075 048/074 045/075 045/072 043/081 048/076 042/062
21/U 21/B 11/B 11/U 10/U 02/W 22/W
MLS 044/073 052/073 049/074 048/069 047/080 052/076 047/063
20/U 33/T 11/B 23/W 20/U 02/W 22/W
4BQ 044/071 050/073 048/075 048/068 045/079 051/076 045/061
22/T 32/T 11/B 21/N 10/U 01/U 22/W
BHK 043/069 049/070 046/072 046/065 043/076 049/075 044/060
20/B 45/T 12/W 22/W 20/U 01/U 22/W
SHR 041/073 047/073 044/074 044/068 042/079 047/077 042/054
22/T 21/B 11/B 21/B 10/U 12/W 33/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Des Moines IA
344 PM CDT Mon Sep 5 2016
.SHORT TERM.../Tonight/
Issued at 344 PM CDT Mon Sep 5 2016
The primary concern will be convective trends later tonight. Much
of the precipitation has exited the state with the warm sector
surging northward and the best 0-2km moisture convergence now from
SD across southern MN. Heat indices are now into the mid 90s
central and south. The front is currently on the Siouxland
doorstep and impacts for IA weather will depend on whether it will
develop more surface based soon, or wait for more of an elevated
potential later this evening. Conditions are quite favorable for
supercell development just to our west, and the Bunkers motion
would suggest a more easterly motion if that were to occur. This
would eventually push the outflow and convergence farther south
into IA to be realized by the low level jet and associated
convergence. However examination of visible satellite imagery
currently shows little vertical development along the front.
The more likely scenario, and that supported by most models, is
that strong moisture transport along the 305K isent surface will
produce convection from the Siouxland area across southern MN fed
by 35- 45kts of inflow. The RAP mean wind suggests motion parallel
to the front with Corfidi vectors either neutral or weak from the
same direction. This supports a heavy rain potential just across
our border with precipitable water, specific humidity and
integrated water vapor transport all very near climatological
maxes. Have added heavy rain wording to the forecast north, but
held off on a headline for the moment due to this thinking and
high resolution models highlighting MN rather than IA as well.
.LONG TERM.../Tuesday through Monday/
Issued at 344 PM CDT Mon Sep 5 2016
Active weather pattern sets up this week with periodic severe
weather and heavy rain potential Tuesday into Wednesday. Utilized
a blend of the ECMWF/NAM Tuesday into Wednesday, and then a
ECMWF/GFS blend through the remainder of the forecast period.
Tuesday into Wednesday...Models continue to shift convection
further north during the day Tuesday with the frontal boundary
looking to drape across far northern Iowa into southern Minnesota.
The latest ESRL HRRR, NSL WRF, and SPC WRF have all shifted the
convection further north and delayed the timign until late Tuesday
afternoon. There maybe some elevated convection that develops
during the afternoon within the WAA regime and theta-E advection
north of Highway 30. However, a fairly strong cap remains in place
and the stronger forcing looks to transition further north into
Minnesota through the day Tuesday. Shaved off pops across the
southern portions of the forecast area during much of the day
Tuesday. With the drier forecast, leaned toward increasing winds
and temperatures for Tuesday with the good mixing and strong
surface pressure gradient. The stronger winds are likely to occur
over the southern two-thirds of the CWA.
Strong moisture transport continues across the state Tuesday night
into Wednesday. Deep moisture convergence will be along or just
north of the Iowa/Minnesota border by 00z Wednesday and gradually
transitions south-southeast through 12z Wednesday as the front is
slow to move. By around 12z Wednesday, the front looks to remain
oriented from around MCW to ALO southwest to DNS to CRL area into
east-central Nebraska. A strong atmospheric river continues to
pump moisture into this area with warm layer clouds depths
remaining persistent around 4000 meters between 00-12z Wednesday
and even through much of the day Wednesday. Another shortwave
tracks across the state Wednesday providing additional
thunderstorm chances. Certainly a long duration moderate to heavy
rain threat and have introduced mention of heavy rain across
northern Iowa during this time. With the PWATs ranging from
1.5-2.0 inches Tuesday into Wednesday, slow storm motion and
possible training of thunderstorms, the potential exists for flash
flooding Tuesday night into Wednesday. River flooding is also
possible over portions of northern Iowa, but had low confidence to
issue any hydrologic related headline due to the uncertainty of
frontal boundary location as well as the delayed timing of the
convection. May need to consider at least a flash flood watch over
the far northern portions of the CWA for late Tuesday night into
Wednesday. Some of the contigency river forecasts (max QPF vs min
QPF) for the Cedar River Basin reach just over minor flood stage
(if at all) and not until late in the work week into the weekend
for any potential impacts. The only concerned location would be
Cedar Falls (CEDI4) if the max QPF forecast comes true in this
basin.
As far as the severe weather potential, agree with the Slight Risk
shifting further north where the boundary is located on
Tuesday/Tuesday night. 0-6km bulk shear ranges near 35-40 knots over
far northern Iowa Tuesday evening with decent MLCAPE values present.
Initial storm mode looks to be supercells but will likely quickly
transition into heavy rain producers. Cannot rule out the threat for
wind late tomorrow night into Wednesday morning over far northern
Iowa with the amount DCAPE present (500-1000J/kg). MCS maintenance
probability over the north ranges around 40-50% overnight into
Wednesday morning.
Thursday into Friday...Surface high pressure builds into the state
Thursday but is quickly removed a fairly decent surface low pressure
and mid-level shortwave moves northward into the state by Friday
morning. A strong trough and cold front move south late Friday night
into Saturday, with Saturday morning looking to be somewhat windy
behind the front. GFS is slightly more potent than the ECMWF, but
both are in agreement with the timing of the trough Friday night.
&&
.AVIATION.../For the 18Z TAFS through 18Z Tuesday afternoon/
Issued at 106 PM CDT Mon Sep 5 2016
Primary concerns will be convective trends and LLWS into Tue
morning. Thunderstorms along the IA/MN border should continue to
lift north away from TAF sites this afternoon leaving VFR
conditions and brisk southerly winds in place. These brisk winds
will sustain themselves above the boundary layer into the night
producing LLWS ahead of the NE/MN frontal boundary, mainly
affecting north and west sites /KFOD/KMCW/. Convection is also
expected to develop along the front and reach at least the
northwest third of Iowa overnight. Have only included VCSH at
KFOD/KMCW for now until confidence in timing and locations becomes
more clear.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
SHORT TERM...Small
LONG TERM...Podrazik
AVIATION...Small
Area Forecast Discussion
National Weather Service Miami FL
439 PM EDT MON SEP 5 2016
.SYNOPSIS...
Numerous showers and thunderstorms will continue into
early evening over most land areas. During the evening, showers will
slowly diminish with the loss of daytime heating. Through Friday,
as high pressure builds over the Atlantic, deep southeast flow
will favor an enhancement of shower/thunderstorm activity across
the interior and Gulf regions of South Florida. During the nights,
activity will favor the east coast. Expect near normal temperatures
for this time of year.
&&
.DISCUSSION...
Water vapor imagery continues to show a mid to upper level
moisture boundary draped east to west across South Florida.
Analyzing the 12Z morning sounding, there were multiple indicators
of an active day with respect to convection. First, CAPE values
were around 3500 J/KG, a sufficient amount for strong updrafts. No
appreciable temperature inversion (cap) could be seen, which had
favored early initiation. A PW value of 2.14 represented a very
moist atmosphere. This, in combination with weak winds in the low
to mid levels, has led to increase risk of flooding today in low
lying and poorly drained areas. The HRRR and Hi-Res WRF model keep
convection ongoing through at least early evening. Have left
likely pops in the grids over all land areas to account for this.
The water spout potential will remain elevated along the coastal
waters due to light winds in the lower levels. Tonight, after the
loss of diurnal heating, shower and storm activity should diminish
with highest chances remaining along the east coast. On Tuesday,
the 12Z GFS keeps the aforementioned mid and upper level moisture
front over the CWA with the highest PW near the very southern tip
of Florida. Thus, chance to likely pops have been added to this
region Tuesday afternoon. The main impacts from these storms will
again be heavy rain, brief gusty winds, and frequent lightning.
Wednesday through Thursday, high pressure building over the Atlantic
will bring a return to the more typical summerlike pattern to South
Florida with east flow prevailing. Expect highest chances of
afternoon, sea breeze driven showers and storms over the interior
and Gulf Coast. During the nights, activity may shift towards the
east coast. From Friday into the weekend, long range models
advect higher moisture up from the tropics and increase storm
activity.
Beaches: From this evening through Wednesday, models project a 3-4
foot 11-12 second swell, generated by Hermine, to drop southward
down our Atlantic coastal waters. This scenario would create
elevated surf along the Atlantic beaches and an enhanced rip current
risk. These conditions may warrant marine and rip current products
to be issued later this afternoon.
&&
.AVIATION...
Weak boundary sliding south into region helping to
generate SHRA/TSRA over ATLC that are occasionally brushing east
coast. Coverage increases across rest of region after 14Z becoming
sct-nmrs, but confidence in timing is low so will keep VCTS
rather than TEMPO groups. TEMPO MVFR conditions with most
activity, occasional IFR with heavier showers. Prevailing ENE flow
through the day.
&&
.MARINE...
High pressure ridge continues to build across the
Atlantic through late in the week with chance of showers and
thunderstorms throughout the period. A 11-12 second swell,
generated, by Hermine, will push south through the Atlantic
coastal waters late today through early Wednesday building seas
close to exercise caution to advisory along the Atlantic waters
late tonight into Tuesday. Seas could peak around 3-5 feet east of
Miami- Dade/Collier counties and 5-7 feet in the coastal waters
east of Palm County. Conditions will begin to improve by late
Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 77 88 76 88 / 50 40 30 40
Fort Lauderdale 77 89 77 88 / 50 50 40 40
Miami 77 89 77 90 / 40 60 40 40
Naples 75 90 73 89 / 30 50 20 50
&&
.MFL Watches/Warnings/Advisories...
FL...None.
AM...None.
GM...None.
&&
$$
SHORT TERM...27/JT
LONG TERM....27/JT
AVIATION...ALM
Area Forecast Discussion
National Weather Service Omaha/Valley NE
342 PM CDT MON SEP 5 2016
.SHORT TERM...(tonight through Thursday)
Issued at 337 PM CDT MON SEP 5 2016
Latest water vapor imagery in combination with RAP analysis shows
a mid level trough axis extending from southwestern Canada into
the Great Basin with a lead shortwave drifting northeast across
Wyoming and into into the western Dakotas. 12z upper air analysis
showed an 850mb thermal ridge extending from the southwestern
CONUS all the way into southern MN with dewpoints around +16 to 17C
aided by a 50kt southwesterly low level jet. PW`s remain high with
the 12Z observed sounding indicating 1.82". At the surface this
afternoon...a cold front extended northeast from lee side low
pressure over western Colorado across central Nebraska and into
northeast South Dakota. Latest visible satellite shows a
shrinking stratus deck over western and north central Nebraska
behind the frontal boundary with a congested CU field over
northeast Nebraska.
Focus for thunderstorms late this afternoon/evening will be along
the surface front with latest CAMs indicating development as
early as 20-22Z across northeast Nebraska. RAP analysis shows cap
is quickly diminishing in this area with MUCAPE values around
2500-3000 J/KG. This activity should persist for a few hours
before moving off to the northeast with the main activity
forecast to develop across northwestern Kansas and move along the
boundary overnight. CAMS also show potential MCS development
across north Central Nebraska overnight and sliding along the
Nebraska/South Dakota border. Thus, much of the CWA should remain
dry overnight except the north.
The front begins to slowly drift southeast Tuesday with increasing
potential for heavy rain along and behind the boundary.
Possibility for a few supercells does exist across a portion of
the northern CWA Tuesday afternoon where a slight risk has been
outlooked from SPC.
Front finally slides south Wednesday when mid level shortwave
kicks through. Again...the potential for heavy rain exists with
strong to severe thunderstorms. Wednesday night into Thursday
looks dry as the frontal boundary pushes south of the forecast
area.
.LONG TERM...(Thursday night through Monday)
Issued at 237 PM CDT MON SEP 5 2016
By Thursday night, the front begins to lift north as another mid
level shortwave ejects into the Central Plains. A stronger
shortwave trough will move through the Northern Plains Friday
pushing a much stronger cold front through the CWA leaving the
area dry for next weekend.
&&
.AVIATION...(18Z TAFS for KOFK...KLNK and KOMA.)
Issued at 1202 PM CDT MON SEP 5 2016
Generally expect VFR conditions at KOMA and KLNK through the
period. Low level wind shear should occur again tonight as surface
winds decouple but boundary layer winds aloft increase into the 40
to 50 knot range.
For KOFK...did include a PROB30 group for TSRA later this evening.
Depending on how the front progresses and how convective outflow
develops...low clouds could move into KOFK. For now did mention
MVFR ceilings toward 13z but ceilings could drop lower than that
and sooner. Confidence just not high enough though at this time to
go with IFR.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Kern
LONG TERM...Kern
AVIATION...Miller