Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/09/17
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1153 PM EDT Mon May 8 2017
Issued at 1152 PM EDT MON MAY 8 2017
Based on latest radar trends with scattered showers moving into
the CWA, made some tweeks to the pops to better cover the ongoing
coverage. This resulted in some updates to the weather and QPF as
well. Will continue to monitor radar and latest Hi-res models in
case any more updates need to be made over the next few hours
before the morning forecast package. All changes have been saved
and sent to NDFD/web.
UPDATE Issued at 1120 PM EDT MON MAY 8 2017
Did a quick update to fine tune the PoPs and Wx through the next
few hours as a few showers have drifted into the area a bit ahead
of schedule. Also, fine tuned the T and Td grids per the latest
obs and trends. An updated ZFP will be issued shortly along with
the grids sent to the NDFD and web servers.
UPDATE Issued at 845 PM EDT MON MAY 8 2017
00z sfc analysis shows high pressure retreating from the area in
the face of an approaching, and developing, warm front. Mid level
clouds are sliding into the area ahead of this boundary. This
should prevent the development of too large a ridge to valley
difference and one that lasts through the night. However, there is
a short window of time where a few of the eastern valleys could
drop down into the low to mid 40s before rebounding after
midnight as thicker and lower clouds move into the area. Have
reflected this in the grids with this update. Currently, readings
are in the upper 50s to lower 60s most places, though those
eastern valleys are in the mid 50s. Meanwhile, dewpoints vary from
the mid 40s west to the low and mid 30s east - helping to give
those eastern cold spots room to drop through the rest of the
evening. Winds have dropped off, too with most places just light
and variable. Have also adjusted the arrival of the showers late
tonight from southwest to northeast by dawn per the latest HRRR
run. Kept the threat for thunderstorms in the forecast for well
after midnight and into the morning hours of Tuesday. Finally,
touched up the T and Td grids per the latest obs and trends. These
updated grids have been sent to the NDFD and web servers.
.SHORT TERM...(This evening through Tuesday night)
Issued at 314 PM EDT MON MAY 8 2017
At 2 PM surface high pressure was centered over central KY and a
surface low was over southeast South Dakota. A warm front extended
from the low southeast into far western KY. A blocky upper air
pattern remained in place across North America with closed upper
lows centered over southern Quebec and south of California with
upper ridging in the plains.
The warm front will move northeast across KY tonight and Tuesday
before becoming stationary over northeast KY or WV. Showers are
expected to break out ahead of the front tonight and a few
thunderstorms will also be possible. Temperatures tonight are
tricky, as very dry air remains in place ahead of the warm front,
and temperatures would drop quickly in the sheltered valleys
after sunset unless clouds move in quick enough. Clouds and
scattered showers over IL and IN are moving southeast, and current
forecast increases clouds fairly quickly this evening. We did
lower temperatures a few degrees from the standard blend in the
far eastern valleys since this will be last area to cloud up
tonight. However did not go nearly as low as COOP MOS would
indicate for colder spots. Coldest spots are generally in the mid
40s in the forecast for tonight, but COOP MOS points towards mid
to upper 30s.
Showers and a few thunderstorms will continue on Tuesday, mainly
across the northeast part of the forecast area. On Tuesday a
short wave trough will dive southeast into the mean long wave
trough in the eastern U.S. and an associated surface low will move
southeast along the front. This will focus shower and
thunderstorms in the far northeast part of our area, with latest
model guidance suggesting the heaviest rains with this will be
north and east of east KY, at least for Tuesday. With the blocky
pattern in place the front will remain quasi-stationary in or near
our forecast area on into Tuesday night, but rain chances will
temporarily diminish after the passage of the wave on Tuesday.
.LONG TERM...(Wednesday through Monday)
Issued at 314 PM EDT MON MAY 8 2017
A quasi-stationary frontal boundary will be located over the Tri-
State area Wednesday morning and the boundary will stay very close
to, if not over, northeast Kentucky through Thursday. Due to it`s
location, PoPs will be highest over north and northeast Kentucky
Wednesday through Thursday, but cannot rule out a shower or storm
even down south along the Tennessee border. The front will also
cause a sharp temperature gradient with highs Wednesday and Thursday
ranging from the lower 70s over northeast Kentucky up to the upper
70s to low 80s over the Cumberland Valley region. The front will
drop south slowly Thursday evening through Friday evening bringing
our best chance for showers and storms areawide. Given the multiple
rounds of storms expected, there remains a concern for flooding to
develop and will continue to highlight that potential in the HWO.
Once the front drops to our south, a drier and cooler airmass will
filter into the region over the weekend. Models have come into
better agreement with the 12z runs bringing another cold front
southward through the area on Sunday. The front is moisture starved
and will not offer any PoPs with its passage right now. A
reinforcing shot of cooler air will then follow this frontal passage
keeping temperatures near or slightly below normal as we head toward
the new week.
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 830 PM EDT MON MAY 8 2017
Mid level clouds will increase this evening as a warm front
approaches from the southwest. Ceilings will gradually lower
overnight and showers will break out across the region as the warm
front nears the area. A thunderstorm will also be possible late
tonight and Tuesday morning, but whether a TAF site will be
impacted is still uncertain. Thunder chances will begin in the
southwest part of the area after 06Z and after 11Z in the
northeast. Ceilings are expected to remain VFR in the southwest
part of the forecast area, but lower to MVFR in the north and east
by around 12Z. Showers will be most numerous Tuesday morning in
the northeast part of the forecast area where IFR conditions may
develop. Winds through the first part of the forecast will be
light and variable with an increase from the southwest to west at
10 to 20 kts in the downstream portions of the Cumberland Valley
later in the day, Tuesday, while lighter winds remain further
northeast - away from any thunderstorms.
Area Forecast Discussion
National Weather Service Louisville KY
1024 PM EDT Mon May 8 2017
Issued at 1024 PM EDT Mon May 8 2017
Did a quick update to back off PoPs in the western half of the
forecast area overnight. Both the 00Z HRRR and NAM runs are a bit
more east with the wave coming in tonight and suggest additional
convection will develop a little more eastward out toward the I-75
corridor late tonight. Thus, have reduced PoPs over the I-65
corridor and points west. Minor adjustments were made to the
T/Td/Wind grids to bring them up with current observations and the
latest model trends for the overnight period. Updated forecast
products and grids will be available shortly.
.Short Term (Now through Tuesday Night)...
Issued at 259 PM EDT Mon May 8 2017
A few showers have crossed into the northwest corner of the LMK CWA
ahead of a weak wave over the mid-Mississippi Valley. These showers
will continue through the late afternoon and then wane this evening
as the sun sets.
Dew points have been surging northeast today in the Plains and
Midwest on the south wide of a warm front developing from South
Dakota to the Pennyrile. The front will drift to the northeast
tonight and allow some of those higher dew points into the lower
Ohio Valley. An upper wave traveling from the lower Great Lakes to
the upper Ohio Valley will help to spark showers and thunderstorms
along the warm front after midnight tonight. The best chances will
be northeast of the surface boundary closest to the upper wave and
in region of best isentropic lift.
Tomorrow the wave will push off to the east and should take the bulk
of the convection just off to our east as well, so while we`ll have
showers and thunderstorms in the forecast it won`t be an all-day
rain. The best chances for rain should be in the morning. There will
be decent elevated instability with MUCAPE around a thousand near
the front in the afternoon, but a sufficient trigger may be lacking
and deep moisture will decrease from what we will have seen in the
morning. Deep layer shear looks weak as well, and heights will be
rising slightly. Wet bulb zero heights indicate that if storms do
get going they could drop small hail.
Temperatures Tuesday will vary a lot from one side of the front to
the other. Southwestern areas will easily get into the 80s. The
northern Blue Grass may get into the lower 70s, but if there`s
enough cloud cover and rain then those areas won`t get out of the
60s. Winds will get a little gusty in the warm sector, probably to
Tuesday night the front will still be nearby with scattered
convection along and northeast. While QPF isn`t very high right now,
we`ll have to keep an eye on southern Indiana east of I-65 for any
water issues if there are several episodes of training storms along
the surface boundary.
.Long Term (Wednesday through Monday)...
Issued at 304 PM EDT Mon May 8 2017
Though we`ll have weak upper ridging Wednesday-Thursday, the surface
warm front mentioned in the short term discussion will remain in or
near the Ohio Valley during that time, keeping showers and
thunderstorms in the forecast. By Friday the front may slide off to
the southeast, but an upper shortwave trof will move overhead for a
continued chance of scattered showers and storms.
The weekend into Monday is a low confidence forecast for now, with
either weak ridging or northwest flow aloft depending on how a
Plains upper ridge develops. Individual ECMWF members and ensemble
mean lean more toward a dry forecast than toward a wet one. GEFS
also seems to lean dry, though not as strongly as the EC. MEX PoPs
are well below normal, the inherited forecast is dry, and neighbors
are dry. So, will continue with a forecast on the drier side for now.
.Aviation...(0Z TAF Update)
Issued at 730 PM EDT Mon May 8 2017
The main TAF concerns are a chance for showers or an isld storm
tonight and breezy winds tomorrow. A disturbance will dive
southeast into the Ohio Valley tonight bringing showers and even an
isld t-storm to SDF/LEX. Most of the evening models still indicate
BWG should remain dry. Convection should affect SDF/LEX mainly
between 7-13Z late tonight into Tue morning. The frontal boundary
associated with this system will lift NE during the day tomorrow so
any late day rain chances will be greatest at LEX. Brief MVFR
conditions are possible in any convection.
Winds will be variable tonight and then predominantly west with
gusts up to 18-20 kts Tues afternoon.
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1101 PM CDT Mon May 8 2017
.UPDATED for 06Z Aviation Discussion...
Issued at 1055 PM CDT Mon May 8 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 307 PM CDT Mon May 8 2017
The surface low of interest is entering southwest MN this afternoon.
Warm air advection in advance of this feature will spawn shower and
thunderstorm development this afternoon and evening. Temperatures
have warmed into the upper 70s and lower 80s in the thermal ridge
axis just ahead of the trough from west central into south central
MN, where dewpoints are creeping up toward the 60 degree mark. Most
unstable CAPE values have increased to around 1500 J/KG this
afternoon in said area, where 700-500mb lapse rates are circa 7.5
degrees C/KM. Therefore, any stronger cells that develop could be
hail producers. The preferred model for convective evolution today
was the HRRR 1km, which indicates the main window of shower and
thunderstorm activity in MN will be between 6 pm and midnight, with
lingering showers over west central WI overnight as the boundary
stalls over northern Iowa.
A few showers may linger near Eau Claire on Tuesday morning, but for
the most part a dry day is expected with low cloud cover gradually
decreasing (but being replaced by increasing mid level clouds from
Temperatures remain mild tonight mostly in the lower 40s to lower
50s, with cooler highs on Tuesday in the lower 60s to lower 70s.
.LONG TERM...(Tuesday night through Monday)
Issued at 307 PM CDT Mon May 8 2017
For the most part the latter portion of the forecast period looks to
be quiet with the bulk of precipitation chances staying to our
south, although there will be better chances areawide toward the end
of the period as we see the main baroclinic zone lift a bit farther
north. Some shower activity could work up to around I-90 or so
wednesday, although the main precipitation looks to be well to the
south closer to the warm front that will extend from the southern
plains into the mid-Mississippi Valley. High pressure from Canada
will assert itself Wednesday night into Friday, helping to displace
the baroclinic zone and any chances for precipitation farther south,
so dry weather and fairly seasonable temperatures can be expected.
By later Friday into Saturday the western ridge looks like it will
start to push eastward, which will help to tighten the northwest-
southeast oriented temperature gradient while a northern stream
shortwave trough drops southeast along it. This should provide for a
window of rainfall potential later Friday into Saturday before high
pressure once again noses in from the north. After that point, the
spread in the model solutions increases, with the 12Z GFS keeping a
surface ridge over the area through Monday, while the ECMWF and
Canadian solutions have sufficient warm advection and some elevated
instability to bring precipitation chances back into the area. For
now there isn`t much reason to deviate much from a blended solution,
which results in the inclusion of chance PoPs over most of the area
later Sunday into Monday.
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1055 PM CDT Mon May 8 2017
VFR with MVFR Cigs possible. Forecast guidance continue to
indicate 1500 to 2500 ft ceilings will develop tonight, but took a
more optimistic approach and raised them up to VFR. Did add
mention of fog at KRNH and KEAU. Winds will become northerly and
northwesterly overnight as a low pressure system moves across the
Last area of thunderstorms will pass through the region by 0430Z
and should not have any other precipitation after that through the
end of the TAF period. Forecast guidance hints at MVFR Cigs
across the region later tonight, but kept the TAFS VFR at this
/OUTLOOK FOR KMSP/
Wed...VFR. NW wind 5-10 kts.
Thu...VFR. N wind 5-10 kts.
Fri...VFR. N wind 5-10 kts.
Area Forecast Discussion
National Weather Service Omaha/Valley NE
348 PM CDT Mon May 8 2017
.SHORT TERM...(Tonight through Thursday)
Issued at 325 PM CDT Mon May 8 2017
Forecast concerns will continue to be isolated thunderstorm
chances this evening then increasing rain and thunderstorm chances
Tuesday night through Thursday morning.
Thunderstorms indeed developed overnight in the expected area from
far northeast Nebraska into western Iowa and points east. Local
rain amounts were generally light with a trace to a few hundredths
of an inch reported at Harlan, Red Oak, and Clarinda, Iowa.
Farther east...half inch hail was reported in DMX`s area at
Bridgewater and a public report of 2 inches of rain at Jamaica in
The clouds thinned and with southwest winds at 10 to 20kt...
temperatures have warmed into the upper 80s and lower 90s ahead
of an approaching cold front. The winds have switched at
KOFK/KLCG/KBVN. GOES-16 satellite imagery show a few puffy cumulus
clouds trying to develop ahead of this boundary. The most recent
Experimental HRRR has a narrow one-county wide area of isolated
thunderstorms from 00Z to 02Z. The RAP hints at something isolated
this afternoon into the early evening with the front in
combination with the h5 trough moving across the Northern Plains.
The NAM/EC are mostly dry and the GFS is a bit more aggressive.
The latest SPC meso-graphics show 1000-1500J/kg MLCAPE with
weakening inhibition to -25J/kg ahead of the front. Heating and
the front should be enough to get a few storms going, however
these should diminish with the heating. Included an isolated tsra
mention early this evening with the front.
The shortwave passes to the east...however the push of the surface
front slows...thus should still in our CWA Tuesday morning. Lows
tonight should be in the mid to upper 50s north, however in the
lower 60s south.
The closed h5 low over CA is a slow mover and is over southern AZ
Tuesday and New Mexico Wednesday. Tuesday will have more clouds,
however the forcing for ascent does not really move into the area
until Tuesday night and Wednesday. There may be an isolated storm
near the frontal boundary, however the better chance will be with
the mid and upper level support Tuesday night into Wednesday where
showers and thunderstorms becoming likely for parts of the outlook
area. Highs Tuesday should be in the 70s/80s and Wednesday in the
The combination of the surface front in Kansas and the closed low
tracking from New Mexico into the Central Plains will set the
stage for locally heavy rain Wednesday night across parts of
Kansas into Missouri. The northern part of the forecast area
should be mainly dry after Wednesday night, however the rain will
linger in the south Through Thursday.
.LONG TERM...(Thursday night through Monday)
Issued at 325 PM CDT Mon May 8 2017
A drier period is forecast for Friday and Saturday with highs in
the 70s. Sunday could bring a few showers and thunderstorms
however there is still poor model agreement at forecast time.
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1202 PM CDT Mon May 8 2017
There is now enough of a chance of TSRA at KOMA late this afternoon
and evening to where a VCTS mention has been included in the 18Z TAF.
Kept ceilings at or above 8000 feet for now, but will amend
forecast if needed based on what happens. A cold front will sink
southward through the area this afternoon and evening, with winds
shifting to northwest and then north with frontal passage.
Area Forecast Discussion
National Weather Service Las Vegas NV
555 PM PDT Mon May 8 2017
.SYNOPSIS...Warmer temperatures with just a few showers lingering
across northern portions of the area Monday before additional
showers and thunderstorms move back into the area Tuesday into
Wednesday on the back side of a departing low pressure system.
Winds will strengthen briefly Tuesday morning, particularly along
the Colorado River, and diminish by the evening. Warming and
drying conditions expected after Wednesday.
.UPDATE...First wave of isolated thunderstorms across southern
Mohave County dissipating as it nears Lake Havasu City currently.
Radar shows next area getting ready to move into southeast Mohave
County east of Wikieup. HRRR plus 18z NAM and GFS show additional
waves of showers along with a risk of isolated thunderstorms moving
west across southern Mohave County. Updated to increase PoPs
generally south of Interstate 40 and east of Highway 95 in San
Bernardino County tonight.
Will also be monitoring trends of ongoing precipitation across
Esmeralda/Inyo and Lincoln Counties over the next few hours.
.PREV DISCUSSION...442 PM PDT Mon May 8 2017
The cut-off low remains the weather maker for the short term.
Lingering showers and a possible thunderstorm are likely in the
northern portions of the forecast area tonight, these areas
include eastern Sierra, Esmeralda County, and Nye County. Tuesday
morning, chances for showers move to the southeast region of the CWA,
primarily in northwest Arizona. By the afternoon, chances for
shower and a possible thunderstorm spread into southern Nevada
and southeast California as moisture wraps around the upper level
low. Although precipitation has been underwhelming for this
particular system, QPF still sits around a tenth of inch for the
Las Vegas valley. Warming in the mid and upper levels should keep
snow levels above the 10000` mark.
In terms of wind, models indicate a frontal feature associated
with the upper level low that will propagate from northwest
Arizona into southern Nevada Tuesday morning. This front will
usher in strong south winds, particularly along the Colorado
River Valley. Wind speeds will peak during the afternoon ranging
between 25 to 35 mph and gusts between 35 to 45. A Lake Wind
Advisory has been issued for Lake Mead and Lake Mohave as
hazardous boating conditions are likely to develop in the morning
and afternoon. If these winds develop earlier in the morning,
patchy areas of blowing dust will likely develop and reduce
visibilities. Winds should settle down tomorrow evening and remain
light through Wednesday night.
Temperatures should remain a few degrees below normal Tuesday and
Wednesday, with cloud cover Tuesday keeping the diurnal
temperature range around 10 degrees.
.LONG TERM...Thursday through Monday.
A dry and persistent breezy to windy pattern with near normal
temperatures appears to be developing for the weekend into early
next week. The medium range models are in good agreement at
depicting an amplified ridge migrating over the southwest states and
Intermountain Region Thursday ahead of a broad closed low over the
Pacific Northwest. The base of this low is then forecast to swing
over California and Nevada Friday and hold through the weekend as
the system circulates over the northwest states. There are various
differences in the models with respect to shortwaves rotating
through the low along with the placement and depth of the closed
circulation. However, it looks likely that this broad low will park
over the northwest states and produce periods of gusty southwest
winds over much of our forecast area through the weekend with highs
generally in the upper 80s to mid 90s across the deserts.
.AVIATION...For McCarran...Winds expected to remain light and
follow a diurnal pattern this evening, with a westerly wind
developing after sunset. Tuesday morning winds will be light and
northeasterly before a shift to southerly around 19Z to 21Z. With
the southerly shift, winds will strengthen to around 10 to 13 kts
with gusts between 15 to 25 kts. Gusty winds may produce areas of
blowing dust reducing visibilities Tuesday morning. Chances for
showers increase Tuesday and are expected last through Wednesday,
with the best chance for shower development occurring after 00Z
Tuesday. Skies are expected to be broken with CIGs around 8000`.
For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty south winds of 35 to 45 mph expected Tuesday
morning along the Colorado River and will progress into southern
Nevada by the afternoon, with gusts decreasing to 15 to 25 mph.
Areas of blowing dust are possible with gusty winds. Showers
expected for northwest Arizona in the morning and spreading into
the southern Nevada and southeast California by the afternoon.
Overcast conditions expected to develop with CIGs dropping to
about 6000` for northwest Arizona by noon. Elsewhere, CIGs should
be around 10000`.
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
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