Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/27/17
Area Forecast Discussion...Updated
National Weather Service Billings MT
842 PM MDT Wed Apr 26 2017
.UPDATE...
One wave of showers is now approaching Billings and a second is
moving through Livingston at this time. RAP merges these two
features in the Billings area and keeps precipitation going all
night over central zones, while most of the other models push
these waves through, dissipating by midnight and trending pops
lower overnight before next wave of energy builds in tomorrow
morning from the southwest. Split the difference between these
solutions and kept chance type pops in for areas west of Hardin
overnight following late evening likelies. Like the trend of
increasing pops from the southwest early to late morning tomorrow
with broad diffluence and QG forcing overspreading surface
convergence and low level isentropic ascent. May be a bit slower
than previous forecast based on 00z models so slowed progression
down a few hours. Overall should be a wet day over the western
2/3 of the forecast area Thursday.
Snow...Temperatures overnight will be held up by increased cloud
cover so looks like snow accumulations will be little to none
below 6000 feet tonight, though much of the area will see at least
a mix of rain/snow overnight into tomorrow morning. Best chance
for light accumulations will be in the Beartooth and Bighorn
foothills and valleys. No changes to the going Winter Storm Watch
this evening. Chambers
&&
.SHORT TERM...valid for Thu and Fri...
Low clouds have been stubbornly hanging around over most of
northeastern Wyoming and eastern Montana. Had to adjust afternoon
high temperatures down several more degrees on this update given
the persistent cloud deck. A batch of rain/snow showers moved
through Billings late this morning bringing around 0.10 inches of
liquid.
A line of showers and isolated thunderstorms has developed from
Nye northward to Harlowton which is pushing into the central
Plains. Troughing begins to develop east of the Divide this
evening as an upper-level shortwave digs into Idaho.
Surface low begins to develop over southeastern Wyoming with a
trough axis northward through the Bighorns and into south central
Montana. Isentropic lift begins to generate the highest qpf area
from Sheridan County northwestward through Yellowstone county by
Thursday afternoon. This trough axis will remain quasi-stationary
through Friday morning. Then it will begin to push southwestward
toward the Beartooth/Absaroka foothills by Friday afternoon.
Models have trended cooler with this system particularly over
northern Wyoming with a rain to snow transition in Sheridan
expected some time on Thursday. This significantly increases the
expected snowfall accumulations for Sheridan and southern Big Horn
County. With this update, I have added those areas to the current
Winter Storm Watch for Thur-Fri. Expecting 6-10 inches of
snowfall for foothills and areas west of Interstate 90, with 4-6
inches in eastern portions of those counties. Still expecting
Bighorn Mountain locations to see 12 to 18 inches of snowfall
accumulation through Friday. Still some uncertainty whether enough
snow will occur in lower-elevations to warrant any advisories, so
I will let the next shifts take a look at that. Walsh
.LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...
Building heights over the area on Saturday as energy near the 4
corners region begins to shift east. This will begin to dry out
the airmass and surface high pressure will be in place to limit
mixing but clearer skies will begin a warmup. Flow regime for
Sunday through Tuesday will be northwesterly with disturbances
bringing showers and temperatures closer to seasonal normals.
Tuesday disturbance is accompanied with a bit more upslope which
allows for better precipitation amounts but nothing significant
compared recent events.
Another pattern shift for Wednesday as a broader ridge shapes up
over the western US while northerly flow still keeps temperatures
cool over Montana and Wyoming, it does however trend drier with a
few diurnal showers due to high soil moistures. The ridge begins
to shift eastward towards the weekend which could bring a round of
above normal temperatures. borsum
&&
.AVIATION...
Scattered showers and isolated thunderstorms will move across the
western and central sections of the forecast area this evening
impacting KLVM and KBIL before dissipating late this evening.
Another round of showers resulting in MVFR conditions will move
into the area later tonight and especially by mid morning
Thursday. Otherwise, VFR conditions will prevail for most areas
tonight. However, the mountains will be obscured throughout the
night. Hooley
&&
.PRELIMINARY POINT TEMP/POPS...
Thu Fri Sat Sun Mon Tue Wed
-----------------------------------------------------------
BIL 036/047 033/045 034/053 036/059 040/056 039/055 038/060
67/O 86/O 42/W 11/B 33/W 33/W 32/W
LVM 032/047 030/045 026/053 033/057 036/054 033/053 033/057
56/O 47/O 42/W 13/W 33/W 33/W 32/W
HDN 035/048 034/049 033/056 035/061 039/058 039/057 038/061
36/O 86/O 32/W 11/B 33/W 34/W 32/W
MLS 034/057 034/055 034/058 036/061 041/059 039/057 039/060
12/O 33/O 21/B 11/U 33/W 13/W 22/W
4BQ 031/053 032/051 033/056 031/059 039/057 038/055 036/059
12/R 44/O 21/E 11/U 33/W 24/W 22/W
BHK 025/054 028/052 030/056 030/059 037/056 035/054 035/057
11/B 11/E 11/E 11/U 33/W 13/W 21/B
SHR 032/043 030/042 028/047 029/054 036/052 035/051 035/055
37/O 87/O 42/W 11/B 33/W 34/W 32/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Watch in effect from 6 AM MDT Thursday through
Friday evening FOR ZONE 38.
WY...Winter Storm Watch in effect from 6 AM MDT Thursday through
Friday evening FOR ZONES 98-99.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Des Moines IA
623 PM CDT Wed Apr 26 2017
...Updated for 00z Aviation Discussion...
.SHORT TERM.../Tonight through Thursday/
Issued at 359 PM CDT Wed Apr 26 2017
The weather will turn quite active into the weekend and early next
week, but initially the concerns through tomorrow will be precip
trends southeast this evening and then frost potential southwest
into Thursday morning. The current situation has a deep PV
anomaly/short wave moving through TX with a large area of
kinematically forced lift moving through the MS Valley, including
some right entrance region effects from a small Upper MS Valley jet
segment. Much of the warm/theta-e advection and frontogenetical
forcing is south and east of Iowa, and should remain that way
tonight. The mid level mechanically forced lift may just brush far
southeast sections this evening with only chance PoPs.
Frost is a concern southwest overnight but there are questions with
regard to wind, temps and cloud cover. HiRes window ARW/NNM runs
suggest some clearing southwest half overnight, however the ESRL
HRRR, HRRR and RAP are both more aggressive and the current stratus
shield still extends well into NE. Winds may not drop below 8kts and
mins are even marginal with no lower than 34F expected. With these
inputs in low confidence have opted to not issue a headline for the
time being. The cloud trends would be the main concern and can be
further evaluated this evening if need be. Although IA will be
thoroughly embedded in the broad mean trough, a subtle short wave
ridge through the MO Valley may give us a brief glimpse of sun
Thursday before the forecast turns.
.LONG TERM.../Thursday night through Wednesday/
Issued at 359 PM CDT Wed Apr 26 2017
The overall pattern will have changed little heading into the later
periods with strong Pacific NW jet continuing to feed short waves
into the base of the mean trough. The next wave of forcing is
expected to lift through the Plains and MO Valley Thursday Night
with a strong baroclinic zone lifting south to north into IA. The
phasing of deep moisture and lift is not there all the time, but
should result in at least some precip into Friday. Have also
mentioned some frost north with temps at or below freezing and skies
mostly clear for a good deal of the night.
After a relative lull to start the weekend, the long wave trough
will deepen and amplify leading to strong MO Valley cyclogenesis
into IA. The ECMWF and GFS are in good agreement and fairly
impressive spreading deformation zone precip into NW with strong
thermodynamic forcing just to the south and east into central IA.
Both models depict tremendous theta-e advection and
frontogenetical forcing leading to likely PoPs into Sunday, even
at this time range. WPC Day 5 QPF forecasts suggest widespread
1-2" accumulations may occur through the weekend. Temperatures
will be right on the brink of being cool enough to support snow,
so there continues to be at least a mix wording into early Monday
morning. Timing as of now suggests the mid/upper level core of the
low will be over IA Sunday Night, which would be a more favored
time for snow rather the during nearly early May daytime heating.
Gusty winds will also need to be watched with a strong MSLP
gradient just ahead of and then behind the low. Confidence is
certainly not high, with a noted dry slot also rotating into IA,
but strong forcing and precip rates at night could lead to accums
and overwhelm any melting at night.
Some low end PoPs linger into Tue and Wed but forcing is somewhat
non-descript as another NW flow wave attempts to deepen the
central CONUS mean trough. Temperatures through the extended will
certainly not be warm with cool and wet the primary themes, even
beyond valid forecast period.
&&
.AVIATION.../For the 00Z TAFS through 00Z Thursday evening/
Issued at 623 PM CDT Wed Apr 26 2017
MVFR ceilings will prevail at all terminals overnight with
perhaps some high IFR ceilings at KMCW. A few showers will also
pass over KOTM this evening before the showers pivot to the east.
Drier air arriving on winds from the northwest will allow for
clouds to break and ceilings to rise into VFR from the southern
terminals to the northern terminals through the day Thursday.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Small
LONG TERM...Small
AVIATION...Ansorge
Area Forecast Discussion
National Weather Service Green Bay WI
1024 PM CDT Wed Apr 26 2017
Updated aviation portion for 06Z TAF issuance
.UPDATE...
Issued at 909 PM CDT Wed Apr 26 2017
Made the previously-mentioned changes to precipitation chances
overnight into Thursday, with higher POPs and QPF in our western
counties. Also adjusted temperatures down a few degrees, which
resulted in greater ice/snow accumulations. Issued a winter
weather advisory for Vilas, Oneida, Lincoln and Forest counties
from 09z-17z/Thu, which matched up well with headlines that DLH
and MQT had issued earlier.
UPDATE
Issued at 629 PM CDT Wed Apr 26 2017
Watching a fairly consistent trend of the meso-models wrapping
pcpn farther back to the west late tonight into Thursday morning.
If this is correct, and if temperature forecasts reach current
forecast values or get a little cooler, we may need to consider
winter weather headlines for a mix of freezing rain, sleet and
snow in our far northwest counties. Will monitor this over the
next hour or two.
&&
.SHORT TERM...Tonight and Thursday
Issued at 235 PM CDT Wed Apr 26 2017
The latest rap analysis and satellite/radar imagery show low
pressure over northeast Wisconsin early this afternoon, with a
trailing cold front extending south into Missouri. Widespread rain
is about to exit far northern WI ahead of the low, and a significant
break exists between this area of rain, and the next area, which is
surging northeast over southern Illinois. This secondary area is
ahead of another surface wave positioned over southern Missouri.
Looking to the northwest, colder air lies just upstream, with
temperatures in the upper 20s to lower 30s from the Arrowhead of
Minnesota to Ironwood. Several obs are reporting snow in these
areas. Forecast concerns revolve around precip trends with the
arrival of the secondary low tonight, and potential for wintry
precip over north-central WI as colder air filters in behind this
low.
Tonight...A complicated forecast. Low pressure over northeast
Wisconsin will depart over eastern Lake Superior this evening.
Between this system and the arrival of a secondary low, will likely
see a lull in the widespread precipitation, though some occasional
drizzle will likely occur over central and north-central Wisconsin.
The secondary low will move towards southern Lake Michigan late
tonight and bring another swath of widespread precipitation to the
area. The heaviest rain remains forecast for eastern WI, where
upwards of a half inch of rain could fall. Amounts will be
considerably less over central and north-central where north winds
behind the low will draw in colder air from northwest Wisconsin and
northern Minnesota. Because of these colder temps, potential
remains for wintry precipitation, mainly over Vilas and western
Oneida/Lincoln counties. A small window may start to open late
tonight, when temperatures cool at the surface and more widespread
precipitation arrives, for accumulating wintry precip in the form of
snow/sleet/and freezing rain. Think any accumulations will mainly
be confined to grassy and elevated surfaces, though cannot rule out
patches of minor accumulations on roadways in the heavier precip
rates. The potential for slippery stretches on roads will likely
end by 8am as road temps warm with solar insolation. Because of the
narrow time window, and uncertainty revolving around temps/precip
coverage, will continue to highlight the threat of slippery roads in
a SPS.
Thursday...Low pressure will continue to lift north over Lake
Michigan and into Lake Superior. Widespread precip will likely be
lifting north on the western flank of the low across much of the
area during the morning, with some wintry precip over north-central
WI. Precip will exit during the afternoon, but mostly cloudy
conditions will linger. Because of the precip and cold advection,
temps will only rise into the middle 30s in the north to middle 40s
near the Lake.
.LONG TERM...Thursday Night Through Wednesday
Issued at 235 PM CDT Wed Apr 26 2017
The first storm will continue to move away from the region
Thursday night. Some wrap around moisture lingering across
the far north to support small chances of precipitation
(mainly over Vilas County) Thursday night. Left Friday morning
dry across the north, but could not rule out a few flurries.
There was a change in the forecast for Friday afternoon into
Friday night as system passes to the south. Several models
depicting light rain across east-central Wisconsin, and as far
north as Green Bay. Have added a chance of rain to account for
this feature. High pressure will then dominate the weather
pattern Saturday into Saturday evening.
Next system approaching from the south a little quicker than
previous runs. This would support more snow at the onset,
especially across the north late Saturday night into Sunday
morning. Do think the heaviest precipitation will arrive by
mid morning across the north, thus any accumulation would
be on the light side and not cause too many impacts. Will need
to see if the system speeds up over the next day to see if
more snow accumulation would need to be added to the forecast.
It appears Sunday is going to be a washout with periods of
rain, mixed with snow across the north during the morning.
System will move across the region Sunday night into Monday
morning. Dry slot may move across our southeast counties
after midnight. Will also need to monitor thunder prospects
across our southeastern counties as well. Do not have thunder in
the forecast at this time since it is still pretty far out.
Across the north, light snow is expected at times with some
snow accumulation possible Sunday night into Monday morning.
Any lingering precipitation comes to an Tuesday with dry
conditions expected on Wednesday as high pressure dominates
the weather pattern. Below normal temperatures are expected
through much of the period. In matter of fact, the latest
numerical guidance indicated no 60s or 70s during the next
seven days at Green Bay.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1016 PM CDT Wed Apr 26 2017
Widespread IFR/LIFR conditions covered all but far eastern WI
late this evening, and ceilings should drop there within the next
few hours, as the cold front shifts through and rain develops.
Another area of significant precipitation will arrive overnight
into Thursday morning, and models are still indicating that it
will overspread our western counties late tonight into early
Thursday. While most of the region will see rain, our northwest
counties, including the RHI TAF site, will likely see a mix of
freezing rain, sleet and snow late tonight into Thursday morning,
as temperatures drop below freezing. It will be a close call for
AUW/CWA, as freezing precipitation may develop just to the west.
At the least, it appears that a rain/snow mix will develop there
Thursday morning. Some improvement in ceilings and visibilities
are likely on Thursday afternoon as the precipitation pulls out to
the northeast.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 4 AM to noon CDT Thursday for
WIZ005-010-011-018.
&&
$$
UPDATE.........Kieckbusch
SHORT TERM.....MPC
LONG TERM......Eckberg
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Grand Rapids MI
1028 PM EDT Wed Apr 26 2017
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 325 PM EDT Wed Apr 26 2017
A few showers and thunderstorms can be expected through Thursday
afternoon as a cold front moves through. Conditions will dry out
for a short period late Thursday through early Friday. Low
pressure will approach on Friday and bring a chance of rain. A
much better shot at widespread rain will come late Saturday
through Sunday as another low pressure area tracks across Lower
Michigan.
&&
.UPDATE...
Issued at 1028 PM EDT Wed Apr 26 2017
Lowered POPs and QPF overnight and into Thursday morning. Models
have been trending drier and last few runs of the HRRR and other
high res models show bulk of precip missing Lower Michigan to the
west tonight and tomorrow. Severe threat also appears to be rather
low overnight despite greater than 50 knots of 0 to 6 km shear, as
instability is lacking.
Instability appears to be limited on Thursday as well but we Will
have to watch for narrow line of convection late Thursday morning
or afternoon that could have strong gusty winds as indicated by
the hi res NMM/ARW.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 325 PM EDT Wed Apr 26 2017
Our focus with this forecast package is on the waves of
showers/storms through Thu, and the chance of rain coming back in
for Fri/Fri night.
There is a dying line of showers over Central Lower that is at the
tail end of an upper vort moving NNE away from the area. This seems
to be just a bit too far north to tap 1000 j/kg of low level CAPE
over the srn portion of the area. This line seems to be some what of
a weak cool front that extends down S of the area. We can not rule
out another shower/storm popping up, but we do not expect widespread
showers/storms until after 00z tonight.
We are expecting a wave of showers/storms to arrive after 00z from
the SSW that are currently in Srn Il. These are associated with
another upper/sfc wave that will move NE through the evening. The
associated low level jet will nose up into the area and strengthen.
The sfc based instability that we see now will diminish, and this
wave will feature mainly elevated instability with it. This will
limit the severe potential with it. There is some decent shear with
healthy wind profiles up the column. The decent wind profiles will
keep an isolated wind threat in, if it could punch through the
stable near sfc layer. Heavy downpours will be possible too with
PWATS up around 1.5 inches.
We will likely see a lull in the rain for late tonight and early Thu
as the nose of the low level jet moves out, and the sfc low remains
to our west. Heavy widespread rainfall looks to stay over WI. We
will see the main cold front push through late Thu morning and early
Thu afternoon. This will likely develop a bkn line of
showers/embedded storms ahead of it with some diurnal heating taking
place before it pushes through. Forecast soundings do not not
support much of a severe weather threat with thin CAPE profiles. The
wind aloft however keeps a threat in before the front moves through.
The front looks like it should clear the CWFA by 19z Thu. A few
showers will remain in the afternoon to the NW as the upper wave
moves through.
We should end up dry Thu night with rain chances then increasing on
Fri again. The current upper system affecting us moves out, and the
leading short wave with the next upper system approaches. Low level
moisture is not exciting, but there may be just enough for a few
light rain showers to make it to the ground into Fri night. Thunder
chcs look too low with this to include in the forecast for now.
.LONG TERM...(Saturday through Wednesday)
Issued at 325 PM EDT Wed Apr 26 2017
Only small changes were made to the going grid forecast, as the
models are in good agreement and fairly steady. Active weather is
expected through much of the long range forecast.
Showers will be ongoing across Southern Lower Michigan Saturday,
with thunderstorms becoming possible Saturday night through Sunday
night. Widespread rain, could be heavy at times through the weekend.
Showers will continue into Tuesday.
Rainfall totals of one to two inches are likely Saturday night
through Sunday night with locally higher amounts possible.
Temperatures should be fairly close to normal through the long range
forecast period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 756 PM EDT Wed Apr 26 2017
VFR conditions expected to continue through 06Z although scattered showers
and thunderstorms are possible late this evening. Periods of MVFR
are possible after 06Z as ceilings lower blo 3000 feet at times.
Looks like more scattered showers and a few thunderstorms again
after 12Z.
Southwest to south winds overnight around 10 knots then going
west during Thursday with gusts 20 to 25 knots.
&&
.MARINE...
Issued at 325 PM EDT Wed Apr 26 2017
We are extending the Small Craft Advisory out through 06z Fri
morning with this forecast package. The initial advisory was mainly
for the winds out ahead of the system. We are now to the point that
the winds behind the system on Thursday need to be dealt with. These
will be the strongest Thu afternoon, and the waves will come down
enough finally Thu night.
&&
.HYDROLOGY...
Issued at 325 PM EDT Wed Apr 26 2017
Confidence continues to grow that we will have an increasing flood
risk as we head into the weekend and next week. The GFS, GEM, and
ECMWF all have been indicating a pattern that will produce
significant rainfall for our region, likely on the order of 2" to 3"
or more. When that much rain falls across the entire reaches of the
major basins - Grand, Muskegon, and Kalamazoo - there will be some
significant rises. Trends will continue to be monitored.
Smaller rivers and streams are going to be highly responsive to this
type of rain, with abrupt rises possible. Residents along smaller
rivers and streams should be aware of the risk for these types of
changes late into the weekend and early next week.
At this point it is too early to tell exactly how high the rivers
will get, but flood stage may be exceeded at many locations
potentially.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 2 AM EDT Friday for LMZ844>849.
&&
$$
UPDATE...Ostuno
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...63
AVIATION...Ostuno
HYDROLOGY...Hoving
MARINE...NJJ
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1054 PM EDT Wed Apr 26 2017
.UPDATE...
Issued at 1054 PM EDT WED APR 26 2017
The latest HRRR and other CAMs remain in decent alignment with
latest radar trends. These models still bring showers and perhaps
a few thunderstorms into the Lake Cumberland region by 11Z to 12Z.
This line could even slow down some, as the upper level trough
does take on a more negative tilt. The next issue tonight will be
valley temperatures, and did opt to lower from previous forecast
given the latest trends. However, it will be tricky to time the
actual low given the cloud cover moving into the region. Overall
think we could still be looking at a 10 degree split from the
ridges to the valleys. Otherwise, gravitated grids to latest obs
and trends.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 300 PM EDT WED APR 26 2017
The short term portion of the forecast will feature above normal
temperatures and a period of showers and storms on Thursday. A
fast moving cold front is forecast to move across the Ohio and
Tennessee valley regions during the day on Thursday. The
precipitation should begin moving into our southwestern and
western counties early Thursday morning, and should be exiting the
area early Thursday evening. The latest model data is suggesting
that instability should be elevated across the region, which would
help mitigate any threat of severe weather. However, wind decent
wind shear may exist tomorrow while the front is passing through,
so an isolated severe storm with damaging wind gusts cannot be
ruled out at this time. With precipitation and extensive expected
to spread across the area tomorrow, temperatures will not be able
to warm nearly as much as they have the past couple of days, but
we should still highs max out in the low to mid 70s, which is
still slightly above normal for this time of year. Low
temperatures the next two nights should be in the 50s and 60s
tonight, and in the 50s tomorrow night.
Southerly winds will begin to pick up and become gusty overnight
and tomorrow, as the front approaches and the regional pressure
gradient strengthens. Isolated gusts of 15 to 20 mph cannot be
ruled out.
.LONG TERM...(Friday through Wednesday)
Issued at 333 PM EDT WED APR 26 2017
Southwest flow will be in place aloft across eastern Kentucky
Friday through the weekend with ridging off the southeast coast
while a deep trough gets carved out over the central CONUS. At the
surface, a quasi-stationary frontal boundary located initially
along the Ohio River will sag south into the area Friday night.
After a dry and warm day on Friday, shower/thunderstorm chances
increase overnight Friday night, especially over the Bluegrass and
Gateway regions which will lie closest to the boundary. Models
indicate decreasing instability and shear parameters during the
night so severe weather is not a major concern.
Forecast models lift the warm front to our north Saturday into
Sunday placing our area firmly in the warm sector and likely
capped from much if any convective development, although cannot
rule out a shower or storm completely. Temperatures will warm well
into the 80s both days, along with dewpoints in the 60s, making
it feel very summer-like. Showers/storm chances then increase
quickly Sunday night into Monday morning as the potent storm
system wraps up and tracks into the Great Lakes, forcing a cold
front across the local area. Models show quite the wind field
accompanying the frontal passage so despite unfavorable timing and
insignificant instability, will have to monitor this system
closely for a strong wind threat as the front passes through.
The front quickly clears the area on Monday leaving behind a
cooler, less humid airmass. After a brief respite Monday night and
Tuesday, both the GFS and ECMWF indicate another shot at
showers developing by the middle of next week as an open wave
drops into the central CONUS, renewing southwest flow aloft over
our area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 734 PM EDT WED APR 26 2017
VFR conditions are the story to begin the period and will remain
that through much of the night. However, a strengthening LLJ will
introduce the potential for LLWS overnight under calm conditions.
The system that will help induce the jet will also bring the
chances of showers and thunderstorms by around the dawn hours in
the morning. Right now sticking with low end MVFR, but perhaps
IFR would not be out of the question at times in heavier storms.
Also winds will be light to begin the period, but we could see
some gusty winds with any stronger storms. Also winds will veer
around to the west on the back of the front tomorrow afternoon and
could be gusty in the afternoon given good mixing.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...AR
LONG TERM...ABE
AVIATION...DJ
Area Forecast Discussion
National Weather Service Marquette MI
832 PM EDT Wed Apr 26 2017
.SHORT TERM...(This evening through Thursday)
Issued at 431 PM EDT WED APR 26 2017
WV imagery and RAP analysis indicated a mid/upper level trough from
the eastern Dakotas through Oklahoma resulting in ssw flow through
the wrn Great Lakes. One of several shortwave troughs lifting
through Upper Michigan supported an area of light to moderate rain
through the nrn cwa. There was a lull in the pcpn upstream over WI
with mainly patchy light rain or drizzle. The next main upstream
shrtwv was moving into sw Missouri. At the surface, 994 mb low
pressure was located over ne WI with a trough extending to the ne
through centrl Upper Michigan into se Lake Superior. Much colder air
prevailed behind the trough over the nw cwa with temps in the mid
30s while temps had climbed into the lower to mid 50s over the
south and east.
The short range models have trended slightly to the west with the
area of heavier pcpn associated with the shrtwv lifting into the
area as the sfc low moves through Lake Michigan. Expect the
heavier band of pcpn mainly btwn 09z-15z. Additional QPF in the
0.25-0.50 inch range will be likely over much of the area from
late tonight through Thursday morning.
Temps should climb slightly this evening central as the low lifts to
the northeast but should fall off by late evening as low level caa
increases behind the low. Although there is still some uncertainty
with where the strongest temp gradient will set up, there is a high
enough probability that temps will be at or below freezing over the
higher terrain of the west by late tonight. to expand the winter
weather advisory into wrn portions of Marquette county. Similar to
today, the strongest icing is likely on trees and power lines as the
ground remains warm enough to minimize icing on the roads. Overall
ice amounts could still approachin a quarter inch in some locations.
A changeover to snow and sleet is also expected over the west third
as the warm layer aloft shrinks and dissipates.
.LONG TERM...(Thursday night through Wednesday)
Issued at 410 PM EDT WED APR 26 2017
Main weather concern in the extended will be below normal
temperatures along with a stronger system possible with a wintry mix
Sunday into Monday.
Thursday night: The low pressure system that has been bringing all
of rain and wintry mix to portions of the area will exit to the
northeast during this time period. Moisture will continue to wrap
into the area through much of the night; however, the better forcing
will lift to the north and east with the low. 850mb temperatures
will drop into the -7C to -9C range, which will be sufficient to
allow for lake effect rain and snow showers for west to west
southwest wind favored locations. This would be mainly focused over
the Keweenaw Peninsula and at this point it looks as though the QPF
and snow ratios would be fairly low.
Friday through Saturday: A surface ridge and drier air is expected
to build into the area during this time period allowing skies to
become partly cloudy with only minor chances for rain and snow
showers, again, the main focus would be early in the day Friday over
the Keweenaw Peninsula. Temperatures are expected to be slightly
below normal through this time period.
Saturday night through the extended: Low pressure is expected to
develop over the Southern Plains late Saturday night and slide
through the Upper Great Lakes Sunday into early next week. Models
are in general agreement on a bigger system sliding through the
area; however, timing and placement differences continue with the
solutions. The GFS/Canadian and the latest EC all have similar
tracks and timing; however, the GFS is deeper with the surface low
and upper level low and the Canadian is a bit farther west than
previous model runs. These models each have the low moving out of
the area Tuesday afternoon. The previous runs of the EC have been
keeping the surface low and 850mb low farther west, taking the low
over the western U.P. If the GFS/Canadian and now the latest EC are
correct there could be substantial accumulating snowfall across
portions of the west half of the U.P.; however, if the older EC
solutions are correct, then most areas may end up seeing mainly rain
with maybe even some dry slotting expected over the east half. Until
better sampling occurs with this system it is likely that there will
continue to be variances in the models, with improvement expected by
Friday as the wave of energy is better sampled. Consensus is still
the way to go at this point in the extended due to the reduced
confidence in the system track. This will give a mix of rain and
snow central, rain changing to snow west and mainly rain east. Dry
weather is then expected Wednesday into Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 827 PM EDT WED APR 26 2017
A sfc trof over Upper Michigan will result in poor conditions at
KIWD/KCMX/KSAW through this fcst period under periods of showers and
considerable low-level moisture in the vcnty of the trof. IWD/CMX
will be down to IFR with periods of LIFR tonight into Thu morning.
LIFR conditions should continue at SAW through tonight with some
improvement Thu morning as winds become nnw with a more downslope
component. Shallow cold air will filter into western Upper MI for
a change to -fzra at KIWD and KCMX tonight. Expect modest
improvement late Thu at KIWD and KSAW as drier air from the west
allows cigs to improve to low end MVFR.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 524 AM EDT WED APR 26 2017
Northeast gales to 45 knots continue over west and central Lake
Superior into this evening. By late tonight into Thursday morning
winds will begin to subside to 20 to 30 knots as winds become
northerly. Late Thursday through Friday, winds will further decrease
to 10 to 20 knots as winds become westerly. Winds of 10 to 20 knots
are expected through the weekend but could see much stronger winds
to at least 30 kts next Monday as strong low pressure system lifts
across the Great Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 1 PM EDT /noon CDT/ Thursday for
MIZ001>004-009-010-084.
Winter Weather Advisory until 1 PM EDT Thursday for MIZ005.
Lake Superior...
Gale Warning until 11 PM EDT /10 PM CDT/ this evening for LSZ162.
Gale Warning until 3 AM EDT Thursday for LSZ264.
Gale Warning until 2 AM EDT Thursday for LSZ263.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...KEC
AVIATION...Voss
MARINE...JLA
Area Forecast Discussion
National Weather Service Morristown TN
935 PM EDT Wed Apr 26 2017
.DISCUSSION...Forecast mostly on track this evening as we await
the arrival of showers and thunderstorms moving in from the west.
Still expecting activity to weaken as it moves into our area. The
only change to the forecast was to slow the onset of precip.
Previous grids had slight chance pops in for Plateau by 2 am EDT
Have now pushed that back until 5 am EDT based on latest RAP and
HRRR runs which both show later arrival. All other elements look
good. Will send out new zones to reflect aforementioned changes.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 64 76 55 85 / 50 70 10 10
Knoxville McGhee Tyson Airport, TN 62 76 55 85 / 20 50 10 10
Oak Ridge, TN 63 77 54 85 / 30 50 10 10
Tri Cities Airport, TN 54 77 53 85 / 0 40 20 10
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&
$$
SR
Area Forecast Discussion
National Weather Service San Francisco Bay Area
852 PM PDT Wed Apr 26 2017
.SYNOPSIS...Isolated showers have ended in most areas, but remain
a possibility over the hills from Santa Clara County southward
this evening. Otherwise, dry weather is forecast through the
weekend and into next week. Locally breezy conditions are
expected over the next couple of days. Strongest winds will be
near the coast during the afternoon and early evening hours, and
in the hills late night and morning hours. A warming trend is
forecast through the weekend and into early next week as high
pressure builds over the region.
&&
.DISCUSSION...As of 8:50 PM PDT Wednesday...KMUX radar indicates
isolated light showers over the southern Diablo Range at the
present time. The latest WRF and HRRR models forecast continued
isolated shower activity across the southern Diablo Range and over
the hills of Monterey and San Benito Counties through late
evening. But for the most part, dry weather is expected overnight.
Dry weather is then forecast regionwide for the remainder of the
week, through the upcoming weekend, and on into next week. In
addition, expect much warmer temperatures by the weekend, with
warm, dry weather expected to continue into next week as high
pressure builds over California. But before the warmest weather
develops, our region will experience blustery conditions for the
remainder of the work week, with locally gusty winds at the coast
and in the hills.
An upper low is forecast to gradually deepen over the
Intermountain West over the next few days. Meanwhile, an upper
level ridge will be amplifying off the west coast. In between
these two pressure centers, brisk northwest flow will develop
across California. West to northwest winds will increase along our
coast on Thursday afternoon and remain gusty through Thursday
evening. Coastal wind gusts as high as 35 mph are possible during
this time. Winds will then gradually decrease near the coast on
Thursday night, but at the same time north winds will increase in
the hills. Wind gusts up to 40 mph are possible across elevations
above 1000 feet late Thursday night and Friday morning.
This same wind cycle is forecast to repeat from Friday afternoon
through Saturday morning, with another round of brisk winds
expected near the coast Friday afternoon and evening, and in the
hills late Friday night and Saturday morning. Although locally
blustery conditions are forecast over the next couple of days,
winds are expected to remain below advisory levels in most areas.
Winds will decrease in all areas by Saturday afternoon.
Temperatures will warm over the next few days as drier air moves
in and we see more sunshine. But the most robust warming will
occur on Saturday as the upper ridge offshore begins to build
eastward over California. By Saturday highs will warm into the
70s near the coast and into the lower 80s inland. Saturday`s highs
will be as much as 15-20 degrees warmer than today. A shortwave
trough moving over the top of the ridge over the weekend may stall
the warming trend on Sunday, but then renewed warming is
anticipated as we move through the first half of next week.
&&
.AVIATION...as of 5:49 PM PDT Wednesday...A robust influx of
moisture compared to April climatology will continue to interact
with a surface cool front located off northwestern California.
This front will accelerate to approx 30-40 mph moving southeastward
across the Bay Area and north Central Coast this evening and
tonight; additional pockets of light rain or drizzle are quite
likely up until frontal passage.
Preceding this front nearly saturated air up to approx 7 thousand
feet is causing IFR cigs to develop with spill-over of IFR now
extending eastward across the San Francisco Peninsula. Based on
the WRF model IFR will quite likely continue to spread into the
East Bay and South Bay through this evening with lowering confidence
as to if and when cigs/vsbys may lift later in the forecast period.
This incoming change of air mass following the cold front is very
shallow based, the NAM shows cooling at 925 mb not beginning until
Thursday morning thus the caveat here is it could be slow clearing
tonight into Thursday morning specifically along the immediate
coastline and nearest the bays. KMUX is mostly if not entirely
echo-free at the moment due to the shallow based nature of this
present weather pattern.
Vicinity of KSFO...IFR cig persisting this evening, possibly seeing
a return to MVFR cigs beginning 06z though timing is low to very low
confidence. If W-NW winds happen to increase with gusts up to 20-25
knots as forecast mixing may help lift cigs somewhat. WRF model leans
toward a gradual reduction in humidity, but not until much later tonight
into Thursday morning. Coordinated with CWSU office.
SFO Bridge Approach...San Mateo Bridge reports BKN cig as low as 1,300
feet, similarly plenty of saturated air will continue to reach into
the approach this evening.
Monterey Bay Terminals...MVFR lowering to IFR as similar to the Bay
Area greater amounts of moisture will consolidate this evening prior
to the arrival of a cool front. Off/on showers or drizzle tonight.
Clearing Thursday with MVFR/VFR probably returning mid-late morning.
&&
.MARINE...as of 4:52 PM PDT Wednesday...Northerly flow will
increase across the entire region tonight and Thursday as high
pressure builds. The stronger winds will result in steep wind
waves and fresh swell. These hazardous conditions will persist
into the weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pigeon Pt to Pt Pinos 0-10 nm from 3 AM
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 3 AM
SCA...Pt Arena to Pt Reyes 0-10 nm from 9 PM
SCA...Pt Reyes to Pigeon Pt 0-10 nm from 9 PM
SCA...Pt Arena to Pigeon Pt 10-60 nm from 9 PM
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...SF Bay until 3 AM
&&
$$
PUBLIC FORECAST: Dykema
AVIATION: Canepa
MARINE: MM
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Area Forecast Discussion
National Weather Service Omaha/Valley NE
634 PM CDT Wed Apr 26 2017
.SHORT TERM...(Tonight through Saturday)
Issued at 329 PM CDT Wed Apr 26 2017
The chance for freezing temperatures and frost tonight, then rain
moving back into the area Thursday night through Saturday, are the
primary forecast concerns.
Temperatures this afternoon have struggled to gain much from morning
lows, with readings at mid afternoon still in the upper 30s in
northeast Nebraska, to the upper 40s in southeast Nebraska.
Widespread cloud cover and cool northwest breezes made the chilly
temperatures feel even colder. Back edge of cloud cover extended from
central South Dakota into central Nebraska, close to mid level
trough axis noted on water vapor imagery and RAP analysis. That
trough is forecast to swing northeast of eastern Nebraska and
western Iowa this evening. Subsidence in wake of trough should help
to dissipate cloud cover.
At the surface, strong low pressure is expected to move into the
northern Great Lakes region by Thursday morning, with high pressure
ridge extending from the western Dakotas into central Nebraska.
Decreasing winds are expected in our area under this scenario,
however calm winds promoting better frost formation environment is
in question.
However with temperatures already cool this afternoon, continued
cold advection this evening, clearing skis and diminishing winds,
frost formation is still possible where winds drop off
significantly. Already have Frost Advisory going for the southern
half of our area where collaboration with agricultural partners
suggests plants are vulnerable, and see no reason to pull that
advisory now. Farther north where widespread agricultural interests
indicate current plant stages suggest little vulnerability to frost
and high vulnerability to freezing temperatures, have opted to
maintain our current Freeze Warning. Expect temperatures there to
drop into the upper 20s in many spots, and remain there for
several hours overnight. Low to mid 30s are forecast farther
south.
Overall flow pattern will favor a broad trough over the middle of
the country into Friday, then sharpen into the Four Corners region
into Saturday. Impulses rotating through that flow will bring
chances for showers to the area off and on beginning Thursday night.
Dry surface air on northeast low level flow should hold precip off
until the evening, so much of Thursday should have at least some
sunshine before higher clouds begin to thicken later in the day. Mid
level impulse only slowly lifts through the area Friday morning,
bringing a break in precip potential during the afternoon. The
next shortwave is forecast into the Southern Plains Friday
evening, which spreads northeast through Saturday. Models have
trended farther south with this feature and associated
precipitation through Saturday, focusing majority of activity well
to our south. However southeast Nebraska into southwest Iowa will
still be in the likely area of rainfall, with decreasing
likelihood to only a slight chance in northeast Nebraska. Total
rainfall through Saturday is forecast from a tenth in our north to
about three-quarters of an inch in the south.
.LONG TERM...(Saturday night through Wednesday)
Issued at 329 PM CDT Wed Apr 26 2017
Mean mid level trough remains over the middle of the country through
the middle of next week, with a more significant low moving into our
region on Sunday. That low, originating from the Four Corners
region, is forecast into northeast Kansas by Sunday afternoon, then
on into the northern Great Lakes by Monday afternoon. Continued feed
of moisture from the Southern Plains north into the middle
Mississippi and Missouri River Valley regions will promote continued
precipitation chances until wrap-around section of upper low lifts
northeast of our area on Monday. So will have increased
precipitation chances for all of eastern Nebraska and southwest Iowa
Saturday night through Sunday night before decreasing Monday.
Precipitation phase is a question, especially for northeast Nebraska,
and generally for the morning hours of Sunday and Monday. A
continued feed of colder air from the north will drive temperatures
into the 30s for lows, and 850 temperatures are well below zero for
the duration of the precipitation in northeast Nebraska, and for a
time over the rest of our area. Thickness progs are borderline for
much of the period, save for Sunday night into Monday morning in
northeast Nebraska. And both GFS and ECMWF are in agreement. So
there is certainly a potential for accumulating snow in northeast
Nebraska if we can manage a full conversion to snow for a few
hours and rates can overcome warmer ground temperatures. But with
those things still in question now, have maintained our mention
of a rain and snow mix where and when temperatures are forecast to
drop to the middle 30s and below.
Beyond Monday, slightly warmer temperatures, highs in the 60s, are
forecast into mid week as heights gradually rise. However another
shortwave dropping into the region could provide another quick shot
of rain either Tuesday or Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 610 PM CDT Wed Apr 26 2017
Regional obs showing MVFR cigs across ern NE this evening.
However...expect improvement to VFR at all terminals toward
midnight tonight as back edge of cigs shifts east. VFR prevailing
then thru the remainder of the fcst pd.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Frost Advisory from midnight tonight to 9 AM CDT Thursday for
NEZ044-045-051>053-065>068-078-088>093.
Freeze Warning from midnight tonight to 9 AM CDT Thursday for
NEZ011-012-015>018-030>034-042-043-050.
IA...Frost Advisory from midnight tonight to 9 AM CDT Thursday for
IAZ055-056-069-079-080-090-091.
Freeze Warning from midnight tonight to 9 AM CDT Thursday for
IAZ043.
&&
$$
SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...DEE
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
744 PM EDT Wed Apr 26 2017
.UPDATE...
Inherited forecast is on track. Only minor adjustments have
been made to the forecast in terms of the winds and
temperature curve overnight.
23Z water vapor and H4 RAP analysis showing a benign and
seasonable weather pattern in place over the eastern Gulf of
Mexico and Florida peninsula. Significant trough/shortwave
energy currently ejecting out of the central Plains into the
Ohio/TN/Lower MS valleys...will de-amplify and shift east
and northeast through Thursday...as upper ridging over the
eastern seaboard prevents this system from every threatening
our region. The associated cold front will simply run out of
gas as it reaches the FL panhandle...and all synoptic
forcing for showers will shift far to our north through the
day.
Thereafter as we head into Friday and the upcoming weekend,
the synoptic pattern aloft and at the surface takes on a
real summer-like look. The sensible weather will take on a
real summer-like feel. Still a bit early in the season in
terms of thunderstorms, with sea surface temps still a few
degrees too cool, and plenty of hostile air aloft in terms
of thermodynamics, would anticipate the forecast to remain
mostly dry through at least Sunday. Can a very isolated
shower pop up on the sea-breeze one of these afternoon?
Sure, its possible, but the chances of any spot seeing rain
are extremely remote.
The real story Thursday through the weekend will be the very
warm temperatures. Many locations away from the immediate
coast will have good chances at reaching 90, with inland
locations almost certainly surpassing 90. Even the beaches
are going to see temperatures well into the 80s before
afternoon sea-breeze flow knocks there temps back down
toward the lower 80s.
Have a great evening everyone and stay cool in the days to
come.
&&
.AVIATION...
Basically looking at VFR condition prevailing for the
duration of the TAF period. Only exceptions could be at
KLAL/KPGD where a brief period of shallow field fog is
possible in the hour or two surrounding sunrise, however, no
significant vis restrictions are anticipated. Any field fog
burns off quickly in the AM, leading to benign aviation
conditions for the remainder of the day. Light SE winds
early in the AM will increase to between 10-15 knots and
transition south and then SW during the afternoon.
&&
.Prev Discussion... /issued 321 PM EDT Wed Apr 26 2017/
SHORT TERM (Tonight-Thursday)...
Mid/upper level shortwave trough will swing through the Mississippi
and Ohio Valleys moving by to the north of the region with its
associated cold front weakening and dissipating before it reaches
the forecast area. The mid/upper level dynamics will remain well to
the north of the area and with limited moisture not expecting any
precipitation. What we will see however is an increase temperatures
and humidity as the southeast to south flow continues around surface
high pressure ridging west from well out in the Atlantic Ocean with
a shift to southwest near the coast as the sea breeze develops
Thursday afternoon. The increase in low level moisture along with
the mostly clear skies could lead to some patchy fog over inland
areas late tonight. Otherwise temperatures will be above normal with
lows in the mid 60s to around 70 tonight and climbing into the mid
80s coast to the lower 90s inland Thursday.
MID TERM/LONG TERM (Thursday Night - Wednesday)...
An upper level low sits over northern Minnesota with broad
troughing extending over the western half of the U.S. Upper level
ridging continues to hold over the Florida peninsula into the long
term period. The troughing over the western U.S. will further
deepen by Saturday as a closed upper low moves southeast and will
be located over the four corners region. As the trough out west
deepens, the ridge over the southeast U.S. will strengthen and
build northeastward toward Bermuda. The pattern shifts east by the
beginning of next week with the closed upper low now located over
the Great Lakes region and the upper ridge moving east into the
western Atlantic. The upper low moves northeast by midweek and a
quasi-zonal flow sets up over Florida.
On the surface, an area of low pressure over Ontario extends a cold
front southward along the east coast. This front dissipates over
northern Florida as high pressure continues to ridge across the
peninsula through the end of the week and into the weekend. This
will keep a southeast through southwest wind flow over the area
which will result in above average temperatures with the inland
counties seeing daytime highs in the 90`s. Rain free conditions will
also continue through Sunday. An area of low pressure develops over
Missouri on Sunday and extends a cold front south through Louisiana
and eastern Texas. This system tracks east and will bring increasing
rain chances (30-50 POPs) to Florida on Monday and Tuesday.
MARINE...
Southeast to south flow will persist into early next week with a
shift to southwest near the coast each afternoon. Winds will
generally remain around 15 knots or less with seas 3 feet or less.
Winds could reach exercise caution criteria late tonight and
early Thursday morning across the northern waters for a short
period and then across the offshore waters Saturday night and
Sunday night.
FIRE WEATHER...
Relative humidity values are expected to dip into the middle and
upper 30s each afternoon through the weekend, but critical
durations are not expected and sustained winds should remain less
than 15 mph. Therefore, no red flag conditions are anticipated.
&&
.Preliminary Point Temps/PoPs...
TPA 73 88 73 90 / 0 0 0 10
FMY 69 91 72 92 / 0 0 0 10
GIF 67 93 71 95 / 0 0 0 20
SRQ 70 86 71 86 / 0 0 0 10
BKV 63 91 66 93 / 0 0 0 20
SPG 71 86 74 89 / 0 0 0 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...Mroczka
Previous Discussion...Close/Wynn
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
845 PM MDT Wed Apr 26 2017
.UPDATE...
Issued at 844 PM MDT Wed Apr 26 2017
Fairly quiet evening in store across the region as mid/high clouds
have dissipated...and low cloud shield has slowly shrunk over
time. Am a bit concerned that with snow melt this afternoon and
fcst models showing light low level winds...that there might be
some shallow ground fog setting up. Fcst soundings from the HRRR
and NAM12 lean toward that possibility. Not sure that it is worth
mentioning in the grids...but did make a mention in the TAFs.
&&
.DISCUSSION...(This Evening Through Wednesday)
Issued at 337 PM MDT Wed Apr 26 2017
Current surface analysis shows weak high pressure nosing south
out of central Canada and into the Dakotas. Low pressure is
located across southern BC, with cold front stretching across the
Pacific NW. Upper level analysis shows weakening low moving
northeast away from the Dakotas, with cutoff low over southwest
Canada. Strong jet in place from the Pacific NW to the Southern
Plains, with developing shortwave sliding east-southeast across
eastern portions of OR and WA. Clouds have been very slow to
dissipate across our area today, especially from west central to
south central SD. Skies are variably cloudy in most places with
very cool temps, mid 30s to mid 40s. Some showers have developed
south of our northeast WY zones, moving eastward. A few light
showers could clip far southern Campbell County through early
evening.
The next system will begin to impact the area on Thursday, with
chances for showers increasing across northeast WY into southwest
SD, especially by the afternoon. Most of the pcpn should be in the
form of rain during the day as slightly milder air pushes in. Highs
will be in the 40s and lower 50s, warmest over eastern areas where
there will be more sun.
Medium range models still showing differences on track of the system
as it slides down the east slopes of the Rockies and how far east
pcpn will reach into our CWA. Latest GFS and NAM further east with
more significant pcpn compared to EC. A general blend seems
appropriate at this point. For Thursday night, pcpn will expand a
bit further east across the area Thursday night, with the more
significant pcpn moving across southern portions of northeast WY and
possibly into far southwest SD. Rain will change over to snow
overnight across northeast WY and into the Black Hills, and likely
across far southwest SD toward daybreak Friday. This system is not
quite as cold as the last one, so snow can be expected across these
areas in the morning, with a mix or change over to rain in the
afternoon in many areas. Snowfall amounts look to be on the lighter
side in most areas, up to a few inches from the Black Hills to far
southwest SD and most of northeast WY. However, across southern
Campbell County where the heaviest pcpn is forecast, amounts
approaching 6 inches are possible, especially the higher elevations
of southwest Campbell County Thursday night into Friday. Pcpn will
dissipate and shift south of the area Friday night as system moves
into the Central Plains.
The weekend looks mainly dry, but remaining cool, as large trough
lingers over the region. Will see temperatures possibly approaching
average early next week, but unsettled weather will return for at
least the first half of the week. Active northwest flow on the back
side of the trough will bring several disturbances across the area,
with daily chances for showers in most areas. The bulk of the
activity should come during the afternoon and evening hours.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Thursday Evening)
Issued At 605 PM MDT Wed Apr 26 2017
MVFR cigs have become SCT over the last hour as diurnal
heating begins to wane over the KRAP terminal. Additionally, expect
winds to diminish to less than 10kts for both KGCC and KRAP with
FEW/SCT sky conds. Fcst soundings show potential for some light fog
to develop...especially with the melting that occurred today in the
KRAP area...so have inserted brief mention for both locations.
Otherwise look for an increase in cloud cover ahead of next system
during the day Thursday. Inserted some pops for light rain chances
in the KGCC terminal toward the end of the valid period.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
Update...Hintz
DISCUSSION...26
AVIATION...Hintz