Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/23/16
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
922 PM CST Tue Nov 22 2016
.UPDATE...
Issued at 922 PM CST Tue Nov 22 2016
Some light snow may make it into the far eastern CWA but the
chances dont look that good according to the latest nam.
Otherwise, areas of fog will likely remain in the east with
improvement towards morning. The lowest visibilities will be in
the Sisseton Hills region. Updated forecast.
UPDATE Issued at 550 PM CST Tue Nov 22 2016
00z aviation discussion updated below.
&&
.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 340 PM CST Tue Nov 22 2016
Much of the precipitation across the northeast CWA has dissipated
and have therefore canceled the Winter Weather Advisory. Temps have
largely remained above freezing today as well, which has greatly
limited any impacts of icing. The only exception is along the Coteau
ridge where temps are hovering around 31 or 32 degrees. Areas of fog
and drizzle now remain over the eastern CWA, based on web cams and
observations. Although, feel the biggest impacts from any drizzle or
freezing drizzle remain in and around the Coteau region. Inserted
this into the grids for the remainder of the afternoon and evening
hours. Main area of precip associated with the surface low continues
to drift northward across southeast SD, but feel it will be rather
difficult for it to penetrate much into the CWA, if at all this
evening. This is shown by the HRRR and other hi-res models. Have
therefore reduced POPs quite a bit this evening as well as QPF/snow
accums. Will have to monitor fog overnight, especially over the east
within the trough axis where winds will be lightest and moisture
pooling with be the greatest. Tried to time the departure of fog
with the onset of slightly stronger winds on the back side of the
surface trough.
Will also be watching the massive stratus deck sliding south across
ND. Models suggest this will overspread the western CWA later this
evening and have increased sky cover grids accordingly. Looks like a
cloudy night is in store, with clouds continuing into tomorrow, more
than likely. Weak surface ridge over the area tomorrow, with weak
mixing at 925/850 mb as well, so it may be hard to scour things out.
Have also increased sky cover through Wednesday, but will not be
surprised if later shifts have to hold on to cloud cover even
longer. Given the abundance of clouds tonight, have increased lows a
couple degrees, but they still may be a bit too cool for some areas
and later adjustments may be needed.
.LONG TERM...(Wednesday Evening through Tuesday)
Issued at 340 PM CST Tue Nov 22 2016
Thursday we will see a shortwave enter the plains, with a weak
surface low expected to cross South Dakota. Isentropic forcing will
result in some modest vertical lift, upwards of around 10 microbars,
co-located close the vicinity of what is more or less a stacked
low. SREF probabilities for measuring moisture are around 70-90
percent along an axis from Lemmon ND - Mobridge - Redfield -
Watertown. SREF probabilities for measuring 1 inch of snow are also
around 40 percent at the highest, around the Watertown area.
Profiles mainly support snow, though the NAM Mobridge profile hints
that ice introduction may be an issue. Will stick with the mainly
snow forecast at this point.
Friday-Saturday the region will be under a ridge aloft. 850/925mb
temperatures will warm during this time, peaking around a standard
derivation above climo.
Models diverge over the handling of a system moving into the region
late in the weekend, and while differing on timing - both the GFS
and ECMWF bring a well developed system into the northern/central
plains, and future forecasts will need to be monitored for potential
winter storm impacts.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 550 PM CST Tue Nov 22 2016
High low level low moisture will keep IFR/MVFR ceilings across the
region through the night. The ceilings will lift some on Wednesday
becoming VFR at MBG and PIR. There will also be some fog tonight
into Wednesday morning mainly at ATY.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Mohr
SHORT TERM...TMT
LONG TERM...Connelly
AVIATION...Mohr
Area Forecast Discussion...CORRECTED
National Weather Service Corpus Christi TX
907 PM CST Tue Nov 22 2016
.DISCUSSION...00Z CRP sounding indicated a strong inversion
around 850 mbs along with a significant intrusion of dry air at
this level. The mid level short wave trough will move across
Oklahoma and north Texas tonight and be over the Ozarks down
through the Arklatex region by Wednesday morning. Best lift will
remain to the northeast of the area tonight into Wednesday morning
as well as the deeper moisture axis. After looking at latest HRRR
and Texas Tech WRF along with SREF, have reduced PoPs for late
tonight over the northeast part of the area and diminished PoPs
slightly for Wednesday morning over the Victoria Crossroads with
PoPs in the chance category. Prefer the Rapid Refresh Model for
timing on the front Wednesday. Expect the front will arrive over
the northern counties by mid morning and through the southern
Coastal Bend by 21Z and raised wind speeds slightly behind the
front.
&&
.PREVIOUS DISCUSSION... /Issued 559 PM CST Tue Nov 22 2016/
DISCUSSION...See Aviation section for 00Z TAFs.
AVIATION...Cirrus shield will remain over South Texas through the
evening hours with VFR conditions continuing. Low level flow will
gradually weaken this evening as the frontal boundary over
northwest Texas moves toward the region. Expect MVFR ceilings to
develop over the inland coastal plains by 05Z and expand toward
the coast and to the LRD area by 08Z. With weaker winds over the
Brush Country, IFR ceilings and MVFR vsbys in fog will be possible
between 10-14Z. Best chance for showers ahead of the front will be
in the Victoria Crossroads late tonight and early Wednesday
morning. IFR ceilings/vsbys will be possible with the showers.
Isolated thunderstorms could also occur but did not mention in VCT
TAF at this time. The cold front will move into the northern
portion of South Texas 15-16Z and moves through the southern
Coastal Bend by 21Z Wednesday. Isolated showers will be possible
over the coastal plains behind the front in the afternoon but
expect ceilings will be in the VFR category.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 69 80 60 78 64 / 10 30 10 10 10
Victoria 65 75 49 75 57 / 50 50 0 10 20
Laredo 67 79 62 80 63 / 10 10 10 10 10
Alice 67 81 56 79 61 / 10 20 10 10 10
Rockport 71 78 58 74 65 / 20 40 10 10 10
Cotulla 64 79 56 77 62 / 10 10 10 10 10
Kingsville 67 81 57 80 62 / 10 20 10 10 10
Navy Corpus 71 79 64 75 67 / 10 30 10 10 10
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
TMT/89...SHORT TERM
Area Forecast Discussion
National Weather Service State College PA
1029 PM EST Tue Nov 22 2016
.SYNOPSIS...
High pressure will build east over the region tonight and
Wednesday. Weakening low pressure lifting out of the Mississippi
Valley will track just north of Pennsylvania on Thursday...
bringing moderating temperatures and a chance of rain showers
Wednesday night and Thursday...along with light mixed
precipitation across the northern half of the state. Another cold
front will cross the commonwealth Friday night and Saturday,
delivering another brief punch of cold air and a gusty northwest
wind.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Lake effect stratocu over the NW Mtns should give way to clearing
skies late tonight, as high pressure ridge builds into the region.
Mostly clear skies and light wind will allow temps to tumble well
into the 20s across much of the region and into the upper teens
across the snow-covered NW Mtns. Latest HRRR and SREF support the
possibility of patchy valley fog toward dawn across the Alleghenies.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
The sfc ridge axis will be parked over central PA on Wednesday as
increasing high level moisture advects eastward. Model RH time sections
indicate a mostly sunny start to the day, then thickening high
clouds by afternoon. Position of surface ridge and increasing
cloud cover will result in limiting mixing/warming...likely
preventing temps from reaching 40 across the north...and capping
readings to the upper 40s across the southeast counties.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Timing of the precipitation ahead of the next system still looks
good to develop Wednesday evening into the overnight.
The precipitation type will be an issue over the northern 1/3 or
so of the forecast area as the precip moves into marginally cold
air in place over the region.
Latest guidance suggests at least the potential for some pockets
of freezing rain or sleet (wet snowflakes?) Wednesday night into
early Thursday morning with surface temperatures dropping to
freezing in some of the normally cold spots across Northern
Pennsylvania.
Overall QPF appears to be quite light with most locations probably
seeing a tenth of an inch or less, but with increasing travel volume
for the holidays, any kind of wintry mix could cause big
headaches.
The GFS/ECMWF both weaken the cold/occluded front as it enters
the state Thanksgiving Day in favor of a new, albeit weak
secondary low along or just off the Delmarva coast. This weak low
should scoot harmlessly off to the east as the amplifying upper
trough slides into the region for late Friday and Saturday. Enough
cold air could move in to change the rain showers to snow by
Saturday morning.
Unsettled conditions with a gusty NW wind Saturday will yield to
drier brighter weather for the second half of the weekend.
There is consensus among the medium range models that a pretty
hefty front will be approaching by Tuesday, which if it could
bring widespread rainfall would be very beneficial given how dry
we have been this fall.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
VFR conds expected tonight as breezy conditions diminish thanks to
building high pressure.
Wednesday will be quiet. Unsettled weather returns starting Wed
night and persists into Sat. A period of freezing precip/icing
potential will exist generally north of I-80 late Wed night into
Thu.
Outlook...
Wed night and Thursday...MVFR to IFR conditions as periods of
rain spread east across the state. Mixed precipitation/icing
possible across the northern mountains.
Fri...Restrictions likely N/W with scattered rain showers.
Sat-Sun...Restrictions possible N/W with scattered snow showers.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...DeVoir
NEAR TERM...Fitzgerald
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...La Corte
AVIATION...DeVoir/Gartner
Area Forecast Discussion
National Weather Service Duluth MN
848 PM CST Tue Nov 22 2016
.UPDATE...
Issued at 847 PM CST Tue Nov 22 2016
Light snow continued to move north through the far northern
Minnesota and was spreading east through northern Wisconsin as
well. Snow had made it to the International Border and was
occurring at KRZN and likely over northern Bayfield county as
well. We expanded on the Winter Weather Advisory this evening and
included the rest of our northern zones. MNDOT reporting icy roads
over Koochiching county and we have 2 to 4 inches falling across
central and northern Saint Louis county into Wednesday afternoon.
We had some reports of freezing drizzle in our southwest zones.
The RAP forecast soundings suggest mainly snow will occur...but
satellite imagery does show some warmer cloud tops moving through
that area as well as toward Koochiching county so it does make
sense it will continue tonight.
No other significant changes were made to the short term forecast
at this time.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 356 PM CST Tue Nov 22 2016
At 345 PM, skies were cloudy across the Northland. Light snow
continued to push northeastward across the region, with
visibilities and ceilings gradually decreasing throughout the day.
We have recently started to see a good deal of visibilities at one
mile or less. Temperatures were generally in the lower 30s. We are
still seeing a few random reports of unknown precipitation on AWOS
observations, but overall the precipitation appears to be in the
form of snow for most areas.
The focus for the period from tonight through Wednesday will
continue to be snow potential. Based on a thorough model
assessment, it appears the best chance of seeing decent snow
accumulation will be in east central Minnesota, the north shore of
Lake Superior, and northwest Wisconsin. Have continued the winter
weather advisory for the southern half of the CWA, and expanded it
to cover the north shore and the interior portions of the
Minnesota Arrowhead. Total snow accumulation in those areas should
range from 2 to 5 inches, with localized amounts of around 6
inches along the north shore. We should see several waves of snow
move northeastward overnight, leading to a prolonged period of
light snow. We could see a bit of light rain mix in across
portions of the south and in coastal areas by Wednesday afternoon.
The snow will gradually decrease from west to east on Wednesday,
but will linger into Wednesday night across the Arrowhead.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 356 PM CST Tue Nov 22 2016
A weak mid-level wave moves across the upper Midwest late Thursday
then a warming trend aloft as a broad mid-level ridge builds in and
warmer air advects in from the south. Late in the weekend a deep
fast-moving longwave trough will eject out the central Rockies,
deepening over the central/northern Plains Sunday. Despite some warm
air advection ahead of the low, the airmass being advected in will
not bring in much moisture, so mid-levels may be slow to saturate
through the day Sunday, but by Sunday night a wide band of rain
changing to snow in the area of strong mid-level PVA across much of
northern Minnesota and northern Wisconsin, with a rain/snow mix
possible into Monday as the low crosses the mid-Mississippi river
valley before changing back to all snow Monday night through and
continuing through mid-week if not longer as the low continues to
deepen over the mid-Mississippi river valley.
Some concerns for freezing drizzle over the weekend as we lose the
ice aloft but may keep a saturated layer at low levels. Decided not
to include a mention at this point, but across north-central
Minnesota Friday night and late Saturday into Saturday night
conditions may be favorable for drizzle/freezing drizzle.
Temperatures fairly mild with highs in the mid 30s each day and lows
in the mid to upper 20s. (Normal highs for late November are in the
upper 20s, lows usually in the mid teens.)
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 537 PM CST Tue Nov 22 2016
Low pressure was centered in Kansas this evening with an inverted
trough extending well north through the Northern Plains. The low
will move northeast through Wednesday with the inverted trough
moving over the Northland. A prolonged period of light snow will
occur with a few periods of moderate snow occurring as well,
especially from the North Shore down to the Twin Ports region.
Temperatures may be warm enough for some light rain as well,
mainly right along the Lake Superior shore and over portions of
northwest Wisconsin.
Ceilings will lower through the night to IFR or LIFR for most
areas. VSBYs will be IFR/LIFR as well both in snow as well as some
fog later tonight into Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 30 34 28 35 / 100 90 20 10
INL 29 34 26 34 / 80 70 20 20
BRD 31 34 27 34 / 100 50 10 20
HYR 32 35 28 36 / 100 90 30 10
ASX 32 36 30 38 / 90 90 40 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 3 PM CST Wednesday for WIZ001-002-
006-007.
Winter Weather Advisory until 6 PM CST Wednesday for WIZ003-004-
008-009.
MN...Winter Weather Advisory until 9 PM CST Wednesday for MNZ012-020-
021.
Winter Weather Advisory until 3 PM CST Wednesday for MNZ010-011-
018-019-026-037-038.
Winter Weather Advisory until 6 AM CST Wednesday for MNZ025-
033>036.
LS...None.
&&
$$
UPDATE...Melde
SHORT TERM...DAP
LONG TERM...JJM
AVIATION...Melde
Area Forecast Discussion
National Weather Service Grand Forks ND
744 PM CST Tue Nov 22 2016
.UPDATE...
Issued at 744 PM CST Tue Nov 22 2016
Snow has mostly ended across all but the KBDE area. Let the WSW
expire at 01Z as scheduled. However, drizzle has been falling at
KGFK for the last few hours and similarly at KPKD where temps have
been below freezing and they are seeing some icing reported at the
ASOS. Road temps in a few areas, particularly where there is
higher snowpack, are below freezing, but many others have the
forecasted Road temps staying right around the 32 mark. With
uncertainty as to where the line of FZDZ/just DZ will be, along
with some spots seeing slush refreeze possible, have put out an
SPS highlighting slick spots on roads from the Sheyenne and Red
River Valley eastward into MN.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 256 PM CST Tue Nov 22 2016
Current radar and surface observations indicate that all freezing
or frozen precipitation has move east of the Red River into
Minnesota...where it is difficult to find any reports of
precipitation other than snow. Fosston does continue to show UP. Main
urban areas to be impacted by afternoon accumulation will be
Crookston to Bemidji...Thief River Falls...Warroad and Baudette
and all other higher traffic areas across northwestern Minnesota.
The band of snowfall continues to peter out as it advects east of
a Roseau to Crookston line and advisory level impacts are
diminishing. For this reason, have shortened the end time of the
advisory to 7 PM CST. Main impact now will be the light snow
moving over areas that may have received some patchy freezing rain
this morning where temps had fallen as low as 28 F. Less
confidence for advisory level impacts across Otter Tail county but
as we get into higher elevations around Wadena UP is being
reported.
The HRRR has a decent handle on current trends and continues to
decay the band of precip through 23Z. The latest band however does
reinstensify this are in the 01Z to 03Z timeframe however low
confidence we will see redevelopment. Models also vary on
northward extend of precip band across SW Minnesota, however the
HRRR keeps it well to the south of the CWA and will trend POPs in
the southern valley down after midnight. Snow expected to continue
in the far east until early Wednesday morning.
With no strong push of dry air, expect low level moisture to
continue through the day tomorrow and possibly bring some fog or,
with drying aloft, patchy drizzle late tonight in the west and
across the region tomorrow. At the current time not enough
confidence on exactly where this will occur and elect to not add
drizzle to the wx grids but certainly something to look at after
this system winds down. Very little diurnal temperature change
over the next 24 hours and overnight lows should remain just below
freezing with daytime highs tomorrow struggling to rebound with
little solar, possibly reaching the mid 30s by mid afternoon.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 256 PM CST Tue Nov 22 2016
Wednesday night to next Tuesday...Overall seasonal temperature
regime with two time periods with precipitation possible. First snow
departs NW MN Wednesday night with the 500mb fast flow bringing the
next weather system and chance of PoPs across the southern valley
during the daytime on Thanksgiving. Expecting some -sn with maybe a
rasn mix in the afternoon as daytime heating brings temps into the
mid 30s. System departs quickly Thursday night and 500mb ridging
with SFC high pressure spread across the northern plains. This
pattern sets up for the long holiday weekend with highs in the mid
to upper 30s and lows in the 20s.
By Sunday night into Monday the 500mb ridging breaks down with a
along wave trough inducing a strong colorado low pressure system to
develop and move out over the central plains. Placement and track of
that system and the evolution of the upper long wave pattern remain
in flux. Ensemble spreads indicate significant precipitation is
likely somewhere across the northern and central plains with the
potential for a long duration event as the upper low stalls and
pinwheels over the north central CONUS for the mid week time frame.
As this system wraps up to our south and lifts northward PoPs
increase from our southeast to northwest for Monday and Tuesday.
Once again with this system there is minimal cold air to work with
as there remains well above normal conditions across Canada,
where here remains little to no snow pack.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 744 PM CST Tue Nov 22 2016
IFR to LIFR conditions continue at all TAF sites except KDVL,
which is MVFR and has northwest winds on the backside of the
surface trough axis. Even KDVL should see some lowered ceilings
later tonight, The TAF sites along and east of the Red River will
be east of the trought for much of the night, with low level
moisture pooling. LIFR ceilings and lowered visibilities will be
possible in many areas, and some FZDZ is not out of the question
at KBJI and KTVF. Will keep most visibilities around 2-5SM for now,
although some 1SM and lower will be possible. Some improvement in
visibility towards the end of the period, but low stratus will
remain with mostly IFR conditions. Winds will shift to the
northwest but stay below 12 kts.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...JR
SHORT TERM...Speicher
LONG TERM...JK
AVIATION...JR
Area Forecast Discussion
National Weather Service Sioux Falls SD
510 PM CST Tue Nov 22 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 341 PM CST Tue Nov 22 2016
Intense upper level wave moving northeast into far southern Nebraska
this afternoon. Deformation zone to the north has been
concentrating band of light rainfall, with nose of PV advection into
mid Missouri valley finding additional development of showers and
even isolated rumbles at mid afternoon. Temperatures dancing on the
warm side of 32 degrees this afternoon in and around southwest MN,
with just a few spots trying to hold at 32 degrees. Calls around the
area have not revealed any issues with icing, nor has any
groundtruth been found to automated reports of snow at Tracy and
Slayton. Temps aloft remain warm, with a fairly deep layer of 4000-
6000ft suggested to reside in the 0 to +2C range before a small sub-
freezing layer closer to the surface. Challenge for the night will
be dealing mainly with precipitation and potential transition to
snow.
Strong wave lifting northeast is beginning to shear, and expect that
pulse of precipitation will fill into the location of deformation
zone by late afternoon and early evening. HRRR has been handling the
overall trends quite well, and have followed general distribution of
pops along those lines. With rain prevailing through the late
afternoon and even early evening, will take gradual cooling with
dynamic lift and advection of cooler air into inverted trough zone
to begin to push deep enough cooling to start a change to snow.
Total snowfall will be limited by two things, the tendency for the
banding to weaken starting around 03z-06z window, and the time it
takes for cooling to occur. Combination will be likely to bring the
greatest snowfall potential for southwest Minnesota, where up to a
couple inches will be possible. Have continued the winter weather
advisory for this, and potential that even a bit of spotty light
freezing precipitation will occur very late afternoon or early
evening before the change. Inverted trough will continue to push
eastward, and areas ahead of feature will also be susceptible to
some areas of fog, and perhaps even drizzle with depth of saturation
fails to reach ice formation, especially in east central SD.
Some light snowfall may linger early, but will also have shearing
trough causing loss of deep enough saturation to support ice. If not
for the overall trend to subsidence forcing, would think there could
even be a bit of patchy drizzle or freezing drizzle across parts of
southwest MN and northwest IA through the morning.
Temps tonight will be slow to change, and likely not to get below
the lower 30s. Not looking very favorable to get much in the way of
sunshine with trajectory unlikely to allow much drying at lower
levels with weak ridging pushing into the west by late afternoon. As
a result, temperatures will be sluggish to change for most part,
mainly 30s with a few readings into the lower 40s where less/no
snowcover.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 341 PM CST Tue Nov 22 2016
Main focus in the mid range will be on the next open wave system,
which arrives in the central High Plains on Thanksgiving morning and
quickly slides east through the region. While this system looks to
have decent dynamics, with a strong jet moving across the plains,
moisture will be lacking, especially early on in the event. Expect
precipitation to begin moving into north central SD Thursday morning
then expand across the forecast area midday into the afternoon. The
better lift and highest chance for precipitation will be along and
north of I90 and into the Iowa Great Lakes region. Temperature
profiles have warmed a little with the 12z runs, resulting in warmer
temperatures aloft and surface temperatures rising into the mid 30s
to lower 40s as the precipitation threat increases across the area.
Profiles also suggest a lack of ice crystals in the clouds for much
of the day, only changing over to snow as the system is winding down
Thursday evening. As a result, snowfall amounts look very minimal -
less than 1 inch - and mainly centered along and north of highway 14.
Drier pattern settles into the central states Friday into the
weekend with upper level ridging and a warming pattern returning.
Skies will clear while return flow brings light southerly winds on
Friday. Winds pick up a little on Saturday, but will improve
temperatures into the lower 40s and lower 50s.
The next upper level wave approaches on Sunday afternoon and Sunday
night, but there remains some uncertainty in the track and timing of
this system. Both the GFS and ECMWF really strengthen the system,
however the ECMWF has a slower and more westerly track compared to
the GFS. Both models show the potential for this low to linger over
the northern Plains and upper Midwest for several days at the start
of next week. Thermal profiles suggest that the precipitation type
also looks like a mix of rain and snow, but again would depend on
the final track of the low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 509 PM CST Tue Nov 22 2016
Rain across southeast South Dakota into northwest Iowa and
southwest Minnesota will gradually end from northwest to southeast
through the evening. On the northwest edge of the rainfall it
might become cold enough to change to snow before ending.
Otherwise, widespread IFR conditions are expected in low stratus
with some general improvement from west to east tomorrow
afternoon.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...Winter Weather Advisory until midnight CST tonight for MNZ071-
072-080-081-097.
IA...None.
NE...None.
&&
$$
SHORT TERM...Chapman
LONG TERM...
AVIATION...08
Area Forecast Discussion
National Weather Service Houston/Galveston TX
836 PM CST Tue Nov 22 2016
.DISCUSSION...
At 8 PM, a dry line extended from Ardmore OK to KJCT. A cold front
lagged a bit behind extending from about KSPS to KHOB. The front
had begun to accelerate to the east and will likely overtake the
dry line in the next couple of hours. Closer to home, showers and
a few thunderstorms will continue to develop across SE TX tonight.
Water vapor imagery showed a weak disturbance over northern Mexico
earlier this evening and this feature was triggering tonight`s
showers. As the cold front over North Texas nears the region,
additional showers and thunderstorms will develop. Feel the RAP,
HRRR and other short term guidance are handling the situation well
and have leaned toward the RAP/HRRR tonight into early Wednesday.
00Z soundings and the special CLL sounding don`t look all that
impressive with limited CAPE. That said, shear values look good so
can`t rule out an isolated tornado/damaging wind gust as the line
of storms nears the area. Jet dynamics still looking good and SE
TX will lie in an 80 knot right rear quad. Forecast is in good
shape with high PoPs overnight into early Wednesday. Conditions
should dry out quickly on Wednesday and the afternoon is looking
dry with seasonal temps. 43
&&
.PREV DISCUSSION... /ISSUED 543 PM CST Tue Nov 22 2016/
AVIATION...
An upper level shortwave trough was moving over the southern part
of the state into the KCLL area at 2330Z. Am expecting isolated
thunderstorms will be possible for an hour or two (through about
02Z) near or over KCLL and KUTS; although a balloon sounding sent
up at 20Z near KCLL showed a fairly decent cap which indicates
better chances for showers than thunderstorms. Otherwise, a cold
front will then move into the area from the northwest. The latest
high resolution models have the frontal timing close to the 18Z
forecast issuance.
Main impacts will be chances for showers and thunderstorms ahead
of the front. There is an outside chance for MVFR or lower
associated with any of the storms. There is a small chance for
gusty winds with any strong storms that do develop.
Winds behind the front do not look to get much above 10 to 12
knots on Wednesday.
40
PREV DISCUSSION... /ISSUED 347 PM CST Tue Nov 22 2016/
DISCUSSION...
WAA continuing across SE TX this afternoon with the bulk of the
rain (albeit very light) remaining north of the CWA. The front
appears to be just moving into the TX panhandle at present, and
models seem to be on track with its timing so far. Progged low level
wind shears still favorable for the development of strong to
severe storms with the passage of this cold front overnight, but
there is still some uncertainty with regard to the location of the
upper jet/limited instability...especially for locations from the
Houston metro (and further south). Better dynamics are still
forecast to set up over the northern CWA (mainly north of a
Brenham to Livingston line. As such not a lot of changes from what
we are currently advertising.
Rains are expected to clear the coast by late Wednesday morning
as a cool/dry airmass settles over the state. No weather issues
on tap for most of Thanksgiving Day, but the approach of an upper
level disturbance from the west could increase clouds (with
possibly very light POPs over our S/SW counties) during the evening
hours. Scattered rain chances to linger into Fri with the next
cold front moving on through to the coast. The short lived CAA
behind this front will then transition to onshore winds and
increasing temps/low-level moisture for the start of next week.
The increasingly southwesterly flow aloft should also help keep
ISO/Slight CHC POPS in the forecast for this timeframe. 41
MARINE...
Extended the SCEC in the offshore waters with the front looking a
little bit slower to move through, keeping the tighter pre-frontal
pressure gradient in place. But otherwise, not much different in the
general picture. Once the front does approach, winds look to
diminish some, then turn northerly. Some showers and perhaps a storm
or two may survive into the waters as the front moves off the coast
in the mid-morning. Winds should quickly veer through northerly to
northeasterly by Thursday morning, and look to vary between east and
southeast through the end of the week due to another weak front.
Sustained onshore flow becomes re-established for the back half of
the weekend with strengthening winds. The winds look to surpass
caution, and possibly even advisory thresholds Sunday night into
Monday. 25
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 60 68 47 73 53 / 80 30 0 10 20
Houston (IAH) 64 71 50 74 54 / 70 60 0 10 20
Galveston (GLS) 70 74 60 70 62 / 60 60 10 10 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 6 AM CST Wednesday for
the following zones: Waters from Freeport to the Matagorda
Ship Channel from 20 to 60 NM...Waters from High Island to
Freeport from 20 to 60 NM.
&&
$$
Discussion...43
Area Forecast Discussion
National Weather Service Lincoln IL
900 PM CST Tue Nov 22 2016
.UPDATE...
Issued at 900 PM CST Tue Nov 22 2016
The surface low remains well to the west of Illinois, in northeast
Kansas at 0230z. However, a band of steady rains has progressed
well ahead of the front extending from north to south through
Illinois. There already is evidence of some dry air in Missouri
creating a break in the steady rains into far western Illinois.
The latest HRRR shows some re-development behind the current back
edge of the rain band, mainly from 06z-10z before the line
progresses east of I-57. The surface low will only progress into
northeastern Missouri by 16z tomorrow, with additional showers
likely to fill in as we see additional support for precip from jet
stream flows and the upper trough. Waves of dry air wrapping into
the system at mid-levels will create a more scattered nature to
the rains, but low level saturation will help to produce periods
of drizzle as the low finally moves into Illinois Wed afternoon.
Thunder has occurred with the line of showers this evening, and
have expanded the coverage of isolated storms the rest of the
night to include more of the area south of I-74.
It appears that the evaporative cooling that caused some light
snow in northern Illinois earlier this evening has diminished with
the onset of low level saturation. Therefore, we do not expect any
wintry precip in our forecast area the rest of the night, as
temperatures remain relatively steady in the low to mid 40s.
Updated the PoP and weather grids for the next 12 hours to
account for the faster advance of the current band of precip, as
well as thunder potential. The latest forecast info is already
available.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 218 PM CST Tue Nov 22 2016
Early afternoon surface map showing the low center with our storm
system over central Kansas, with a warm front arcing into far
southern Illinois. Extensive dry air in place, with LAPS soundings
still pretty dry below 8000 feet. Some light precipitation is
starting to move into the far western CWA, but temperature/dew point
spreads are still in the 20-25 degree range, so not much beyond very
light rain has occurred.
Associated upper low is seen nicely on afternoon water vapor imagery
just crossing into southeast Nebraska, and this will begin to shear
out as the surface low rides northeast into northwest Missouri by
midnight. The column will continue to saturate from the top down
this evening as precipitation becomes more widespread in the
increasing lift. Would not be surprised to see a bit of graupel or
sleet at the onset with the dry air, but will not add at this time
with very low probabilities. It may take closer to midnight for the
rain to get all the way to the Wabash Valley in southeast Illinois,
but most of the forecast area will be seeing periodic showers by mid
evening and continuing through the night. However, the dry slow
wrapping around the surface low will start to taper the rain west of
the Illinois River by late in the night.
The surface low is progged to track over central Illinois around
midday Wednesday as it weakens. Have continued with the very high
PoP`s over the eastern CWA through the afternoon, but anything
further west will likely be more scattered in nature as the dry slot
fills in somewhat.
.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 218 PM CST Tue Nov 22 2016
The expected departure of the approaching storm system has slowed a
little from previous model runs, suggesting some light rain or
drizzle will linger into Wednesday evening. While the system still
pulls away soon enough for Thanksgiving Day to be dry, trends are
definitely pointing to cloudier conditions for the holiday.
Despite the inconsistency with the wave that had been seen with a
weaker disturbance for Thursday night/Friday, the latest model runs
continue to suggest that this wave will stay north of the forecast
area. This supports dry weather lingering until late in the weekend
and/or early next week as upper-level/surface ridging build across
the region.
As broad upper-level ridging builds across the region late this
week, significant troffing develops across the western United
States. The models are continuing to struggle mightily with how to
handle this trof and any energy that ejects out of it. Significant
spread remains in both inter and intra model ensembles, and run-to-
run consistency has been poor. The unfortunately result of this
uncertainty is keeping precipitation in the forecast from later
Sunday into Tuesday. Some drier periods will undoubtedly be able to
added later once a stronger model consensus emerges.
Temperatures through the period are still on track to be a few
degrees either side of normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 546 PM CST Tue Nov 22 2016
Main concern continues to be with decreasing ceilings as rain
overspreads central Illinois from the west. LAPS soundings confirm
there remains a layer of dry air in the lower levels, but forecast
soundings indicate virga and showers will increase the low level
saturation early this evening. Rain will become widespread over
the terminal sites by 01-02z. That saturation will start to bring
the ceilings down, but upstream observations indicate VFR
conditions should hold until after 06Z. Air mass saturation will
quickly bring the ceilings down to MVFR range at all sites between
06-09Z and will be closer to IFR levels by 12Z. While the rain
will be tapering off around KPIA/KSPI early in the morning, little
improvement in ceilings is likely over central Illinois the rest
of the forecast period. In fact, ceilings could drop to LIFR, and
some residual lift of the saturated ground level airmass could
trigger periods of drizzle during the day tomorrow.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Geelhart
LONG TERM...Bak
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
829 PM CST Tue Nov 22 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 405 PM CST Tue Nov 22 2016
Late this afternoon, the surface low was analyzed across central
Kansas with an inverted surface trough extending north-northeast
into southern Minnesota and we`ve seen a steady stream of light
precipitation today lifting north through the area. It`s quite a
complicated forecast as precipitation type remains a big issue, and
hence confidence in amounts remains very low for being so close in
time to the event. Didn`t make a lot of changes to the going
forecast except to tighten up the PoP gradient across far western MN.
Current thinking for the metro area is the 2-4" range with the
higher end on the north side and the lower end to the south. Then
rain/snow line this evening should be just south of the metro area.
Highest snow totals for closer to 3-5" are expected up the I-35
corridor north of the Twin Cities. In terms of snowfall rates and
timing, the heaviest snow looks to fall this evening from 8PM-
Midnight.
Model soundings from the HRRR, RAP, NAM, GFS all seem to differ on
low level thermal profiles hovering around the critical freezing
mark and just how cool the surface will be. A deep layer from 700mb
down to the surface looks to hover near that freezing mark so very
slight fluctuations will cause big difference in P-type and hence
impacts. We are leaning to the slightly cooler side based on latest
observations and some of the hi-res guidance like the HRRR has
trended to more snow accumulation than it was indicating earlier
today. So, we still think a couple inches of snow is likely in east
central MN through west central WI by midday tomorrow.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 405 PM CST Tue Nov 22 2016
Confidence increasing in some light snow rain/snow Thursday evening
across central and southern Minnesota into west central Wisconsin. A
much larger, more powerful storm will bring widespread rain along
and east of the low track, with heavy snow northwest of the low
track. It is possible that western MN could see the heavy snow with
this system if the low tracks through central Minnesota. Meanwhile
eastern MN and western WI should see rain.
Early afternoon water vapor imagery with GFS 500mb heights showed an
upper level wave approaching the Pacific Northwest, with another one
upstream over the Allucian Islands. On Thursday this first wave will
move west to east across the CONUS. Isentropic ascent ahead of this
wave will lead to saturation, and forecast soundings show some light
precipitation during the late afternoon and evening hours. Thermal
profiles support snow for most locations, with a rain/snow mix on
the southern side near I-90. Snowfall totals of around 1 to 2 inches
seem reasonable, which wont be enough for winter headlines, but
should be enough to make the roads slick for the Thursday evening
travelers.
The weekend looks dry and relatively mild with highs in the mid 40s
to the south and mid 30s for the areas with snow. Late Sunday the
aforementioned second upper level wave will emerge from the 4-
corners region and lift northeast toward the Great Lakes. As of now,
most of the forecast area is in the warm sector of this storm which
means the majority of the precip will fall as rain. The one
exception is western Minnesota where the band of heavy snow could
set up. The super-positioning of the subtropical and polar jet means
this storm has the potential to over achieve, so it should be taken
seriously. However, the variability in the track indicates that it
is too early to determine where the heaviest precipitation will fall
and what type it will be.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 825 PM CST Tue Nov 22 2016
A wintry mix changing over to snow is still in the works this
evening. IFR/LIFR is expected through the morning. The snow will
exit eastern MN in the morning and linger in western WI until the
afternoon.
KMSP...
We think the airport is very close to changing to snow. The
western half of the metro has made the change and the slightly
cooler air is crawling east. Once the switch over is made, it
likely will remain snow through the morning commute. IFR
conditions will continue through the morning.
/OUTLOOK FOR KMSP/
THU...MVFR cigs lingering. Chc -SN Thu night. VRB wind 5 kts.
FRI...VFR. Wind NW 5 kts.
SAT...VFR. Wind SSE 5 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 3 PM CST Wednesday for WIZ014>016-
023>028.
MN...Winter Weather Advisory until 6 AM CST Wednesday for MNZ042>045-
049>053-057>063-066>070-076>078.
Winter Weather Advisory until midnight CST tonight for MNZ041-
047-048-054>056-064-065-073>075-082>085.
&&
$$
SHORT TERM...SPD
LONG TERM...JRB
AVIATION...CLF
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
747 PM EST Tue Nov 22 2016
.UPDATE (Overnight through the upcoming weekend)...
00Z water vapor and H4 RAP analysis show an active but generally
progressive upper level pattern over North America this evening.
Looking from west to east we find a strong split northern stream
jet arriving over the coasts of northern California/Oregon ahead
of a sharp northern Pacific trough. This jet splits into two
distinct branches...with one headed northward parallel to the
coast of British Columbia while the southern split heads inland
over the Great Basin region. Northern stream flow then digs a
broad trough through the central part of the county before lifting
back north through the Great Lakes/Southern Ontario.
Finally...northern stream flow then dives back to the south off
the New England coast around the periphery of a large cutoff upper
low spinning over Nova Scotia. Further to the south...southern
stream jet energy lifts northward from the western Gulf into the
Tennessee Valley...over top a large area of mid/upper ridging in
control of the eastern Gulf of Mexico/FL Peninsula. This upper
ridge has been the dominate player in our weather the past 24
hours...and will remain in control of our weather through the
daylight hours of Wednesday.
At the surface...A broad area of continental high pressure extends
southward from the Great Lakes through the Ohio Valley and then to
the southern Conus/FL. Our position on the southern periphery of
this ridge is providing a light synoptic flow from the northeast
this evening. Over the next 24-36 hours...the slow movement
eastward of the entire ridge axis will shift our winds more out of
the east.
This evening`s 00Z KTBW sounding profile still sampled an
extremely dry atmospheric column over west-central Florida. The PW
value was only 0.44". This value is up a bit from the 0.25" value
Monday evening and the 0.31" reading Tuesday morning.
However...0.44" is still below the 10th percentile of values for
late November. Overall dewpoint depressions through the column are
quite large and will keep our skies clear through the overnight
hours.
The sensible weather forecast for the next 48 hours is generally a
quiet one. Stacked ridging hold control of the region through
Wednesday afternoon...before shortwave energy passing to our north
Wednesday night de-amplifies the ridge and transitions our flow
to a more zonal pattern for Thanksgiving. These are all just
details...as the subtle changes aloft will have little to no
impact on our noticeable weather. The atmospheric column through
the mid/upper levels will remain far to dry to support any chance
of showers associated with the passing energy Wednesday
night...and the shortwave will be off into the western Atlantic by
Thursday morning.
So...the public forecast will simply show dry conditions and
moderating temperatures...both in terms of overnight lows and
daytime highs...during the next couple days. Unlike today`s
crystal clear skies...Wednesday is likely to see a few bands of
high level cirrus overspread our skies ahead of the approaching
shortwave. A bit of low level Atlantic moisture arriving with the
easterly flow and trapped beneath the subsidence inversion around
850mb should also support a shallow few-sct cumulus field during
Wednesday afternoon. Therefore...the change in forecast from
Tuesday to Wednesday will be slightly warmer and partly sunny as
opposed to sunny. Thanksgiving will see temperatures up another
degree or two. Many area are likely to see high temps approach 80
degrees north of the I-4 corridor...and into the lower 80s further
south. A weak onshore component to the winds developing during the
afternoon will keep temps in the 70s along the immediate coast.
Dry and seasonably warm conditions make an appearance in the
forecast once again for Friday. Looking ahead to the
weekend...expecting another push of cooler and drier air to arrive
later Saturday or Saturday night...but nothing that is going to
ruin any outdoor plans for the second half of your holiday
weekend.
Enjoy the continued stretch of dry and warming weather. The
National Weather Service in Ruskin would like to wish everyone a
fun and safe Thanksgiving holiday weekend! Gobble Gobble...
&&
.Aviation (23/00Z through 24/00Z)... VFR conditions prevail for
all terminals through the remaining evening hours with light NE/E
flow. Some patchy and shallow MVFR ground fog is possible between
09-13Z for KLAL and perhaps KPGD...but no significant or lengthy
restrictions expected. VFR conditions prevail for the duration of
the daylight hours Wednesday across west-central and southwest
Florida under a few- sct cirrus shield and a few-sct shallow
cumulus fields (bases between 4-5KFT) during the afternoon.
&&
.Marine...
High pressure currently centered to the north of the coastal
waters will slowly weaken and settle southward over the next
several days...keeping winds and seas generally low. A brief
period of winds near 15 knots is possible away from the coast
tonight...but will quickly diminish Wednesday morning. A weak sea
breeze component turning winds onshore is possible along the
immediate coast each afternoon through Friday.
&&
.Preliminary Point Temps/PoPs...
TPA 56 77 63 81 / 0 10 0 0
FMY 55 80 63 83 / 0 10 0 10
GIF 55 77 61 82 / 10 10 10 10
SRQ 56 77 61 82 / 0 0 0 0
BKV 48 77 54 81 / 0 10 10 0
SPG 60 75 64 80 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Beach Hazards Statement through Wednesday evening for
Coastal Sarasota.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...14/Mroczka
Area Forecast Discussion
National Weather Service Billings MT
304 AM MST Wed Nov 23 2016
.SHORT TERM...valid for Tdy and Thu...
Patchy dense fog and stratus moved into Fallon County last evening,
occasionally reducing visibility to a quarter of a mile in KBHK.
Visibility has not been consistently very low so have held off on
a Dense Fog Advisory. Will continue to monitor for this
possibility as HRRR has been showing dense fog through 16Z today.
Will otherwise issue an SPS as needed.
Water-vapor imagery showed a baroclinic leaf developing in an area
of upper difluence ahead of an elongated Pacific trough moving
onto the coast. The trough will approach the region today bringing
increasing q-vector convergence to the central and western zones.
Moisture will increase over the W this afternoon, bringing a
chance of rain and snow showers to the area, especially over the
mountains. Raised wind speeds in the gap areas today as winds in
KLVM were gusting above 30 mph and the Stillwater Mine had gusts
to around 50 mph. The gap effect will cease when daytime mixing
kicks in later this morning. High temperatures were on track to be
in the 40s.
Northern branch of the splitting trough will move over the area
tonight with strong q-vector convergence moving quickly through
the area through Thu. morning. Jet divergence from the left-front
quadrant of a jet passing S of the area will also bring lift to
the region. A weak pacific cold front will cross the area as well.
Time-heights showed that the strongest vertical motion will be
over the mountains and foothills, with decent dendritic growth in
these areas. Otherwise, the lift looked weak and short-lived. The
system continued to show steep lapse rates. Went with WPC QPF
amounts and blended snow ratios. The snow will taper off over the
E on Thu. morning. Expect close to an inch W and S of KBIL with
1-2 inches over the foothills. Westerly winds will not favor
upslope for the foothills. Had 3-5 inches over the mountains.
Given the expected low snow amounts, will pull the mention of the
system from the HWO, but continue with a Weather Story. Impacts
will be slick roads in places and short reductions in visibility.
Upper ridging will build over the area behind the trough on
Thursday. Lee troughing will support 50 mph wind gusts in the
gap-flow areas. The lee trough will strengthen during Thu. night,
bringing possible 60 mph gusts later in the night. Will continue
the HWO/graphic for the winds. Arthur
.LONG TERM...valid for Fri...Sat...Sun...Mon...Tue...
Broad ridging builds into the area for Friday and Saturday for
warmer and dry conditions. Western foothills areas look to be
windy with gap wind areas around Livingston and Nye seeing
occasional strong gusts over 50 mph. Pattern begins to change with
a cold front Saturday night into Sunday bringing below normal
temperatures and a chance for snow showers into the middle of next
week. Models still having a difficult time pinning down specifics
with this pattern change over our area. They do seem to be
agreeing on a strong storm to impact the Upper Great Plains into
the Great Lakes Tuesday into Thursday. Will have to see if this
system shifts track west at all which could impact eastern zones.
Arctic air that was forecast a few days ago for the later extended
continues to moderate with time, and latest runs while below
average don`t look too bad with highs in the lower 30s and lows in
the teens to lower 20s. Chambers
&&
.AVIATION...
IFR or lower flight conditions will persist late morning along
and north of a Miles City to Alzada line as area of stratus and
fog has built in. KMLS taf site is right on the edge of this
stratus deck and will likely be in and out of it several times
through late morning. KBHK will see periods of visibility around
1/4sm.
The rest of the area will be VFR today. A quick moving system
will bring increasing shower activity to western areas by late
afternoon and early evening, tracking east through the area
tonight. MVFR to local IFR conditions can be expected as this
system moves through along with increasing mountain obscuration.
Chambers
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Thu Fri Sat Sun Mon Tue
-------------------------------------------------------
BIL 046 030/044 028/046 030/048 030/039 026/035 024/034
1/B 80/U 00/B 00/B 01/B 21/B 33/J
LVM 047 026/041 028/047 029/047 025/039 023/035 021/033
3/W 90/N 10/N 01/N 02/J 22/J 53/J
HDN 047 028/045 023/048 024/049 025/040 023/036 021/036
1/B 70/U 00/B 00/B 01/B 21/B 33/J
MLS 047 028/048 025/050 025/051 026/042 024/039 022/038
0/B 41/B 00/B 00/U 01/B 21/B 33/J
4BQ 048 028/045 023/050 024/052 026/041 022/036 020/035
0/B 73/J 00/U 00/U 01/B 21/B 33/J
BHK 042 024/044 021/050 021/052 023/040 019/034 017/035
0/F 33/J 00/U 00/U 01/B 21/E 43/J
SHR 042 023/040 018/047 023/048 021/037 018/031 014/028
0/B 71/N 00/U 00/B 01/B 21/B 43/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service North Platte NE
323 AM CST Wed Nov 23 2016
.SHORT TERM...(Today and tonight)
Issued at 304 AM CST Wed Nov 23 2016
Today and Tonight...a dirty arctic ridge producing stratus across
the Dakotas and ern MT is forecast to sag into ncntl Neb this
morning and then move east this afternoon and tonight as low
pressure deepens across the cntl high plains. The risk to the
forecast is temperatures along and east of a line from KVTN-KBBW
will remain in the 30s behind the arctic front today while areas
south and west rise into the 40s to near 50. The forecast leans on
the cooler RAP and HRRR models plus bias correction. This holds
highs in the 30s around KONL but rise to lower 40s at KVTN and mid
40s at KBBW.
A blend of bias corrected guidance produces lows in the upper 20s to
30 with south winds and mixing. Low pressure will deepen west of
Rapid City and then drop into nwrn Neb by morning. The model
consensus suggests a return of stratus along or east of highway 83
as the arctic air and moisture is pulled back west.
.LONG TERM...(Thursday through Tuesday)
Issued at 304 AM CST Wed Nov 23 2016
For Thanksgiving...most locations will see dry conditions. The
exception will be across the Nebraska/South Dakota border where a
quick moving short wave will track eastward. Precipitation will
start off as snow across the northwest before quickly transitioning
over to all rain. The snow across mainly Sheridan county early
Thursday will be light with little to no accumulations expected.
While there`s still some uncertainty in the track and intensity of
this system, most models are indicating a warmer boundary layer
throughout Thursday keeping precipitation in an all liquid form as
the system moves eastward throughout the day. Have increased winds
behind the system on Thursday afternoon from the previous forecast.
Gusts could increase to near 40 mph for locations west of highway
83. Winds diminish after 6pm.
The system moves into Iowa by Thursday night as high pressure builds
back into western Nebraska. Upper level ridging and surface high
pressure remain over the region through the first half of the
weekend. The next weather system arrives on Sunday night bringing
the potential of some wintry precipitation to central Nebraska. Due
to uncertainty in the track of this system, details about
precipitation type is hard to determine at this time. For now,
precipitation will likely start off as rain on Sunday afternoon,
before switching over to snow after sunset and temperatures begin to
drop. Snow will continue across the eastern half of the forecast
area through Sunday night. These locations (areas east of highway
83) will see the highest snow accumulations. For now, will keep snow
totals on the modest side, only accumulating near an inch.
The low pressure system moves north and east of the area by Monday
night allowing another weak high pressure system to build northward
into the central Plains for the middle of next week.
Temperature wise... after highs on Thursday in the low to upper 40s,
we will have a brief warm up for the weekend. Highs rise into the
50s for Friday and Saturday, before cooling down again Sunday. High
temperatures remain below 40 degrees through middle of next week.
Low temperatures remain fairly steady in the low to mid 20s through
the beginning of next week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1130 PM CST Tue Nov 22 2016
Will see general improvement to ceilings across western NEB rest
of tonight as sky cover erodes from the NEB Panhandle eastward.
Latest satellite imagery shows clearing working into the eastern
NEB Pandhandle and far western NEB Sandhills. Elsewhere, there are
areas of sub-VFR ceilings in portions of north central NEB.
Uncertainty remains in whether or not low stratus will build
through north central NEB and impact the KVTN terminal. Current
thinking is that low stratus will build gradually westward as
clearing moves into central and eastern NEB Sandhills. Will need
to monitor this overnight. Furthermore, don`t think stratus will
impact KLBF as it builds west at this time. Ceilings across north
central NEB should then improve mid morning to early afternoon
tomorrow. Otherwise, winds will remain elevated between 6-12 kts
rest of tonight. Tomorrow, lighter winds can be expected and winds
will shift from northwesterly in the morning to southerly by the
afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...Kulik
AVIATION...ET
Area Forecast Discussion
National Weather Service State College PA
1046 AM EST Wed Nov 23 2016
.SYNOPSIS...
A ridge of high pressure will slide east across Pennsylvania
today. Weakening low pressure will track just north of
Pennsylvania on Thanksgiving. Another cold front will cross the
commonwealth Friday night and Saturday, delivering another brief
punch of cold air, a gusty northwest wind and scattered Lake
Effect snow showers.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Skies are clear to scattered as of mid morning, and temperatures
are rising quickly with a light wind.
A nearly north-south 1028mb sfc high pressure ridge will slide
gradually east today bringing abundant sunshine followed by
increasing/thickening afternoon and evening clouds.
High pressure and increasing cloud cover will likely result in
limiting mixing/warming keeping highs generally in the 40s.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
An advisory for a light wintry mix has been issued for the
overnight hours through sunrise Thursday.
Timing of the areas of
light precipitation ahead of the next system still looks on track
to develop this evening (west) into the late night/morning hours
of Thanksgiving elsewhere. The onset of some light rain/wet snow
looks to be 01-02Z across the NW mtns from KFIG and KDUJ north,
and 02-04Z from KUNV to KIPT.
The exact precipitation type continues to be a concern over the
northern 1/3 or so of the forecast area as the precip moves into
marginally cold air in place over that region.
Latest 03Z SREF and 09Z HRRR guidance and other blended model
guidance suggests a low probability for either light snow...ice
pellets or some light freezing rain for a few to svrl hour period
tonight and early Thanksgiving Day. Considering the increasing
travel volume for the holidays, any kind of wintry mix could cause
big headaches early in the day. Coordinated with KBGM and KBUF to
hold off the issuance of a Winter Weather Advisory for the north,
and await better guidance revealing whether it will be a nuisance
snow/sleet event, or a higher impact widespread light freezing
rain event.
Overall QPF (in the form of mainly areas of light rain Thursday)
appears to be quite light with most locations probably seeing a
tenth of an inch or less.
The GFS/ECMWF both weaken the cold/occluded front as it enters
the state Thanksgiving Day in favor of a new, albeit weak
secondary low along or just off the Delmarva coast.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
The weak sfc low should scoot harmlessly off to the east as the
amplifying upper trough slides into the region for later Friday
and Saturday. Enough cold air could move in to change the rain
showers to snow showers by Saturday morning.
Unsettled conditions with a gusty NW wind Saturday will transition
to drier brighter weather for the second half of the weekend.
There is consensus among the medium range models that a pretty
hefty front will be approaching by Tuesday, which if it could
bring widespread rainfall would be very beneficial given how dry
we have been this fall.
&&
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
Widespread VFR will continue into the evening before unsettled
weather returns starting tonight and persists into Sat.
A period of light snow or freezing rain (with potential for icing)
will occur tonight into early Thursday generally along and north
of I-80. Conditions will deteriorate a bit with areas of MVFR
likely over the north as the precipitation moves through.
Thanksgiving day will bring occasional very light rain, and
create restrictions for the northern half of CWA which will
persist through Friday.
Outlook...
Fri...Restrictions likely northwest and central mtns with
scattered rain showers.
Sat...Restrictions possible N/W half in likely snow showers.
Sun...Restrictions possible N/W in scattered snow showers.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 1 AM to 9 AM EST Thursday for
PAZ005-006-010>012-037-041-042.
&&
$$
SYNOPSIS...La Corte/Lambert
NEAR TERM...La Corte/Lambert
SHORT TERM...Lambert
LONG TERM...La Corte/Lambert
AVIATION...La Corte/RXR
Area Forecast Discussion
National Weather Service Lincoln IL
532 AM CST Wed Nov 23 2016
.SHORT TERM...(Today and tonight)
ISSUED AT 317 AM CST Wed Nov 23 2016
08z/2am surface map shows a 1008mb low over northwest Missouri, with
a warm front arcing southeastward into far southern Illinois. Ahead
of this system, light to moderate rain has been occurring across the
KILX CWA since last evening. Latest radar imagery shows the
steadiest rain now focused along/east of I-57...with patchy
drizzle or very light showers further west across the remainder of
the area. As the low tracks slowly northeastward to near
Rockford by late afternoon, the most persistent showers will
continue to occur across the E/SE CWA where categorical PoPs are
warranted. Elsewhere, will only feature chance PoPs for
scattered light showers. Southeast winds will initially gust to
between 15 and 20mph early this morning, but will diminish toward
midday as the pressure gradient relaxes upon approach of the low.
Given decreasing winds and ample boundary layer moisture from the
recent rain, areas of fog will likely develop by late morning then
persist into the evening hours. Once the low tracks into the
Great Lakes, westerly winds behind a passing cold front will put
an end to the scattered showers and help scour out the fog from
west to east this evening. High temperatures today will reach
the upper 40s and lower 50s, while lows tonight drop into the
middle to upper 30s.
.LONG TERM...(Thursday through Tuesday)
ISSUED AT 317 AM CST Wed Nov 23 2016
High pressure will build into the region behind the departing front
for Thanksgiving Day: however, forecast soundings are showing a good
deal of low-level moisture trapped beneath the strengthening
subsidence inversion. The NAM is quite pessimistic, showing
overcast conditions persisting through the entire day into the
evening. Meanwhile, the GFS is a bit faster with some partial
clearing during the afternoon. Based on the amount of boundary
layer moisture in the wake of the current system and the time of the
year, prefer a more pessimistic solution for clearing. As a result,
will go with a dry, but mostly cloudy forecast for Thanksgiving with
highs in the middle to upper 40s.
A fast-moving short-wave currently coming onshore across northern
California will track across the country and skirt central Illinois
to the north Thursday night into Friday. Any precip with this
feature will remain across Wisconsin/far northern Illinois, so will
continue with a dry forecast through Friday and Saturday.
The next significant system progged to impact the Midwest is still
slated for late in the weekend, with the 00z Nov 23 models
predictably slowing its arrival. GFS spreads light rain across much
of central Illinois by Sunday afternoon, while the ECMWF holds off
the precip until Sunday night. Will carry chance PoPs for a few
light showers along/west of I-55 Sunday afternoon, but these will
likely be dropped by later shifts once GFS catches on to the slowing
trend. Once the system arrives Sunday night into Monday, minor
differences in the location of the 500mb low lead to major
differences in QPF fields. While both models show a closed low
lifting into the Upper Midwest and deep-layer southwesterly flow
developing from the Southern Plains into the Ohio River Valley, the
ECMWF is slightly further east. As a result, its swath of heaviest
rain is mainly focused from the Ozarks northeastward into southern
Indiana...while the GFS spreads its rainfall max into central
Illinois. Its still too early to determine which model (if either)
is correct, but have trended toward the ECMWF due to its correct
timing issues initially. As a result, will carry rain chances
across the board Sunday night through Monday night, but will focus
likely to categorical PoPs along/east of I-57. A secondary surface
wave moving along the slow-moving boundary may keep rain chances
alive into Tuesday...mainly across the E/SE CWA. After that,
cooler and drier weather will return for the middle of next week.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 525 AM CST Wed Nov 23 2016
Low pressure over north central Missouri this morning is forecast
to track into north central Illinois this afternoon bringing areas
of rain and drizzle along with deteriorating cigs/vsbys. Southeast
winds continue to gust in a few locations this morning with the
latest ILX 12z sounding showing a veering wind profile just off
the surface with wind gusts to 35-40 kts in the 1500-2000 foot
level. Latest short term forecast suggest a decrease in winds
just off the surface as the low pressure area approaches from
the west today so will hold off any mention of LLWS for a few
hours this morning. The next problem will be this afternoon as
the surface wave approaches. The surface winds will really drop
off to light south to southwest winds with the last several runs
of the HRRR model suggesting vsbys will low to IFR or even lower
in the 21z-01z time frame. Will handle that possibility with a
tempo group for later today.
Once the front shifts across the area this evening, look for
southeast to south winds to become westerly at around 10 kts
and that should help scour out any low vsbys and cigs, at least
into low MVFR category later this evening and during the overnight
hours.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Smith
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
523 AM CST Wed Nov 23 2016
.SHORT TERM...(Today and tonight)
Issued at 304 AM CST Wed Nov 23 2016
Today and Tonight...a dirty arctic ridge producing stratus across
the Dakotas and ern MT is forecast to sag into ncntl Neb this
morning and then move east this afternoon and tonight as low
pressure deepens across the cntl high plains. The risk to the
forecast is temperatures along and east of a line from KVTN-KBBW
will remain in the 30s behind the arctic front today while areas
south and west rise into the 40s to near 50. The forecast leans on
the cooler RAP and HRRR models plus bias correction. This holds
highs in the 30s around KONL but rise to lower 40s at KVTN and mid
40s at KBBW.
A blend of bias corrected guidance produces lows in the upper 20s to
30 with south winds and mixing. Low pressure will deepen west of
Rapid City and then drop into nwrn Neb by morning. The model
consensus suggests a return of stratus along or east of highway 83
as the arctic air and moisture is pulled back west.
.LONG TERM...(Thursday through Tuesday)
Issued at 304 AM CST Wed Nov 23 2016
For Thanksgiving...most locations will see dry conditions. The
exception will be across the Nebraska/South Dakota border where a
quick moving short wave will track eastward. Precipitation will
start off as snow across the northwest before quickly transitioning
over to all rain. The snow across mainly Sheridan county early
Thursday will be light with little to no accumulations expected.
While there`s still some uncertainty in the track and intensity of
this system, most models are indicating a warmer boundary layer
throughout Thursday keeping precipitation in an all liquid form as
the system moves eastward throughout the day. Have increased winds
behind the system on Thursday afternoon from the previous forecast.
Gusts could increase to near 40 mph for locations west of highway
83. Winds diminish after 6pm.
The system moves into Iowa by Thursday night as high pressure builds
back into western Nebraska. Upper level ridging and surface high
pressure remain over the region through the first half of the
weekend. The next weather system arrives on Sunday night bringing
the potential of some wintry precipitation to central Nebraska. Due
to uncertainty in the track of this system, details about
precipitation type is hard to determine at this time. For now,
precipitation will likely start off as rain on Sunday afternoon,
before switching over to snow after sunset and temperatures begin to
drop. Snow will continue across the eastern half of the forecast
area through Sunday night. These locations (areas east of highway
83) will see the highest snow accumulations. For now, will keep snow
totals on the modest side, only accumulating near an inch.
The low pressure system moves north and east of the area by Monday
night allowing another weak high pressure system to build northward
into the central Plains for the middle of next week.
Temperature wise... after highs on Thursday in the low to upper 40s,
we will have a brief warm up for the weekend. Highs rise into the
50s for Friday and Saturday, before cooling down again Sunday. High
temperatures remain below 40 degrees through middle of next week.
Low temperatures remain fairly steady in the low to mid 20s through
the beginning of next week.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 523 AM CST Wed Nov 23 2016
IFR/LOCAL LIFR is underway along an arctic front draped across
ncntl Neb this morning. The LIFR appears to be developing on the
western edge of the front and associated cloud cover.
The front is expected to retreat east this afternoon and be drawn
back westward tonight as a result of sfc low pressure forming
across the cntl high plains. The SREF and other models suggest
IFR/LIFR in low CIGS and fog east of highway 83 tonight. This
suggests VFR will prevail at KLBF and KVTN.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...Kulik
AVIATION...CDC
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
941 AM CST Wed Nov 23 2016
.DISCUSSION...See updated information for land areas below.
&&
.UPDATE...Upper air map analysis this morning shows a sharp trof axis
aligned from Iowa to the Texas/Louisiana border pivoting eastward at
around 25 knots. Within the trof axis, a surface front was also
positioned in the same areas mentioned above. A north to south zone
of precipitable water values (above the mean) extends from the Upper
Mid-West to the western Gulf. Within this zone, precipitable water
values from 1.1 to 1.4 inches, moving into the Lower Mississippi
River Valley, lies between 130 to 160% of normal. Satellite trends
indicate that clouds will be on the increase and thicken through the
course of the day and into tonight as the frontal zone approaches
from the west. Although there is moisture available, a rapid movement
of the better dynamics and a net reduction in frontal ascent suggests
that coverage of showers will be isolated in the near term. This is
advertised in latest gridded forecasts and is very close to the
latest high resolution HRRR and 4KM NAM output. Precipitation amounts
look light, mostly less than 5 hundredths of an inch. /10
&&
.PREV DISCUSSION... /issued 538 AM CST Wed Nov 23 2016/
DISCUSSION...Updated for latest aviation discussion below.
AVIATION...
12Z issuance...VFR conditions through the next 24 hours. Scattered to
broken high clouds with some lower cloud decks and isolated showers
possible for primarily northern portions of the forecast area this
afternoon into early Thursday. Light southeast winds this morning
increasing and shifting to southerly this afternoon before decreasing
again later tonight. /49
PREV DISCUSSION... /issued 420 AM CST Wed Nov 23 2016/
NEAR TERM /Now Through Wednesday night/...A weak return of moisture
to the area will accompany a shift from easterly to southerly flow
this afternoon as high pressure over the southeastern U.S. begins to
push east ahead of an advancing low pressure system currently
located over the Great Plains. As the upper level trough advances
east of the Mississippi River...dampening some along the way...the
associated surface low lifts northeast into the Ohio Valley. The
attendant frontal boundary...currently extending from roughly Kansas
City south towards San Antonio...will push into the lower
Mississippi River Valley by Wednesday afternoon. Models appear to be
trending a little slower with the movement of this front before
stalls and washes out over the area late Wednesday. Southerly return
flow is expected to persist in the low levels between the high
pressure to the east and weakening front to the west through
Wednesday and overnight into early Thursday morning. Given the
dampening upper level trough and northeast track of the surface low,
currently expecting the best dynamics and therefore coverage of
shower activity to remain to the west and north of the area.
However...with low-level moisture increasing through Wednesday and
weak cooling occurring aloft as the upper level low passes over,
models still trending towards some isolated to scattered showers for
the far northern and northwestern portions of the forecast area
ahead of the trough this afternoon. A slight chance for a few
showers will then persist across the forecast area overnight into
Thursday as return flow continues to moisten the low levels and a
second weak upper level trough and cold front approach the area from
the northwest.
High temperatures this afternoon are expected to range from mid to
upper 70`s across the forecast area. Overnight lows tonight into
early Thursday morning will range from low to mid 50`s well inland
to around 60 near the coast. /49
SHORT TERM /Thursday Through Friday night/...A broad upper ridge
will move over the eastern conus on Thursday while an upper shortwave
passes over the northern and central plains. The upper ridge will
shift east over the western Atlantic on Friday, with the shortwave
following in its wake over the Great Lakes and Ohio River Valley
regions. The base of the upper shortwave is also expected dig
further south over the southeast conus Friday night. A weak surface
frontal boundary will be stalled across the forecast area on
Thursday, followed by a reinforcing northerly wind on Friday as a
1030mb surface high pressure area builds from north Texas to the Ohio
River valley. Lingering isolated rain showers will persist across the
forecast area near the stalled boundary on Thursday, followed by dry
conditions Thursday night due to loss of surface heating. A few pop-
up showers will then re-emerge Friday morning southeast of I-65 ahead
of the push of northerly winds, with dry conditions expected in the
afternoon as drier air filters into the area.
High temperatures Thursday will be about 6 to 10 degrees above
normal, ranging from 73 to 80 degrees. Low temperatures Thursday
night will range from 46 to 52 degrees inland areas, mid to upper
50s along the coastal sections, and near 60 degrees at the beaches.
Highs on Friday will be a couple of degrees cooler compared to
Thursday. /22
LONG TERM /Saturday Through Tuesday/...The dry weather pattern will
persist over the weekend as high pressure both aloft and at the
surface dominates the southeast. The overall weather pattern then
gets interesting as a strong upper shortwave over the northern plains
and southern Rockies moves east to the Mississippi River through
Tuesday night. This upper system will be accompanied by a 120 to 150
knot upper level jet ahead of the trough from east Texas to the Great
Lakes on Tuesday, putting our region in the favorable right entrance
region for strong forcing. Both the ECMWF and GFS models have a
powerful surface low across southeast South Dakota Monday morning
with the central pressure nearing 980mb. This surface low is expected
to lift northeast across the upper midwest through Tuesday, with a
possible secondary surface low forming over the southern plains. A 60
knot 850mb jet is expected across the forecast area on Tuesday, and
with temperatures climbing in the mid to upper 70s, expected MLCAPES
to possibly range from 600 to 900 J/KG. Strong low level wind shear
will be in place on Tuesday, with 0-1km SRH values possibly ranging
from 300-400 m2/s2. Deep moisture will also be on the increase early
next week ahead of the system, with precipitable water values
approaching 2 inches. This should result in a severe weather threat
for our area on Tuesday. We will continue to monitor this system and
provide updates through early next week. Isolated to scattered
showers and a few storms will precede the system on Monday and
Monday night, with scattered to numerous showers and thunderstorms
set for Tuesday. /22
MARINE...High pressure at the surface will shift from the
southeastern U.S. eastward over the western Atlantic through
Wednesday night as a weakening front approaches the lower
Mississippi Valley and central Gulf Coast region. Light to moderate
east to southeast flow overnight becomes more southerly to
southwesterly this afternoon into Thursday. A weak cold front pushes
through late Thursday with winds shifting to westerly then northerly
behind the front and increasing in strength Friday night into
Saturday morning. High pressure builds back into the SE US over the
weekend, establishing lighter easterly flow Sunday before shifting
once again to southerly and increasing in strength ahead of another,
stronger looking front approaching the region early next week. /49
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
316 PM CST Wed Nov 23 2016
.SHORT TERM.../Tonight through Thursday/
Issued at 315 PM CST Wed Nov 23 2016
Satellite imagery and trends indicate that the large stratus shield
covering the region is not breaking up at all this afternoon, and
its back edge is only eroding very slowly over Nebraska. With
impending sunset it is likely that the erosion will stall and the
clouds will persist and thicken overnight. This is climatologically
favored and also depicted by several of the high-resolution models
such as the HRRR and RAP. Have increased cloud cover and bumped up
low temperatures a bit overnight as a result. There is some question
as to whether fog will develop late tonight, especially in the
northeast where dewpoint depressions and ceilings will be lower, but
given the light but organized winds and relative lack of radiational
cooling, have held off on a mention for now.
On Thanksgiving Day a surface ridge will cross Iowa bringing calm or
variable winds and likely helping the clouds to persist for the most
part. Late in the day the next storm system will approach from the
west and spread light precipitation into our far west/northwest
counties late in the afternoon. Forecast temperatures and soundings
indicate light rain initially, changing over to light snow in the
northwest by around sunset. Any impacts from this system will likely
come on Thanksgiving night as discussed in the long term section
below.
.LONG TERM.../Thursday night through Wednesday/
Issued at 315 PM CST Wed Nov 23 2016
Will see relatively strong QG forcing across central and northern
Iowa on Thursday night as shortwave crosses the state. Isentropic
lift is also decent across northern Iowa where pressure deficits
fall quickly during the evening. Anticipate precipitation to
spread across the northern third/half of Iowa during the evening
as max forcing crosses the state. May initially be a cold rain in
many locations but should quickly transition to snow as sounding
falls to freezing or below in the low levels. The precipitation
will linger across the northeast for a few hours after midnight
but precipitation should end rapidly in most areas during the
early morning hours on Friday. Accumulating snowfall is expected
along and north of Highway 20 with an inch or two north of state
Highway 3.
There is not much in the way of cold air on the backside of this
small system and in fact, warm advection will quickly resume by
Friday afternoon. This will persist into Saturday as upper ridging
builds across the central United States. Next system approaches on
Sunday with strong moisture advection into the state by Sunday
afternoon. Showers are expected to push into Iowa by Sunday
afternoon and persist into midday Monday as a strong system winds
up across the northern Midwest. Conditions will be quite windy
during this time with surface low central pressure dropping to
around 980mb in western Minnesota. After the system passes, strong
cold advection is expected by later Monday into the middle of next
week with colder temperatures but not much in the way of
precipitation as the airmass will be dry.
&&
.AVIATION.../For the 18Z TAFS through 18Z Thursday afternoon/
Issued at 1140 AM CST Wed Nov 23 2016
Satellite imagery depicts a large field of low stratus clouds
covering the entire region. Most prognostic models attempt to
clear these clouds to the east tonight, but this appears unlikely.
Ceiling heights should rise to MVFR across much of the area this
afternoon, possibly even with a few transient holes, but then
lower back to IFR for the most part overnight and into Thursday
morning. No precipitation is expected, but there may be some light
fog toward sunrise.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Lee
LONG TERM...Cogil
AVIATION...Lee
Area Forecast Discussion
National Weather Service Indianapolis IN
317 PM EST Wed Nov 23 2016
.UPDATE...
The AVIATION Section has been updated below.
&&
.SYNOPSIS...
Issued at 157 PM EST Wed Nov 23 2016
A cold front is going to push past Indiana from the west overnight
and Thanksgiving Day. High pressure behind it will take charge of
our weather into the weekend. A warm front is forecast to pass
Sunday, and another cold front should cross Tuesday.
&&
.NEAR TERM (Tonight)...
Issued at 157 PM EST Wed Nov 23 2016
The main issue is how fast rain will end.
Everything agrees about precipitation decreasing from west to east as
drier air moves in aloft. A combination of the HRRR and CONSShort
models seems to capture well what is being observed. Timing could be
off by several hours. The rain is likely to end slowly. It`s hard to
say when it will switch from very light to nothing at all.
The models concur on ample low level moisture for clouds and
possibly fog.
Different forms of temperature forecasting give similar results.
This suggests the consensus forecast that will be used should be
accurate within 2 degrees or so.
&&
.SHORT TERM (Thursday through Saturday)...
Issued at 157 PM EST Wed Nov 23 2016
The main issue is whether POPs are needed Friday.
All the models have a disturbance passing then. The NAM has it
strong enough to give a chance for showers. Other models don`t.
Given consensus POPs stay below 15 percent, the forecast will be
dry, but it is possible a slight chance will be added later for
Friday.
The period is going to begin with abundant boundary layer moisture
from today`s rain. Between that and the disturbance Friday, we`ll
likely see a lot of clouds into Friday night. There may be fog
Thursday morning. Starting Friday night clouds should decrease as
anticyclonic flow develops and drier air arrives.
The underlying thermal fields are fairly close, supporting consensus
for the temperature forecast.
&&
.LONG TERM (Saturday night through Wednesday)...
Issued at 157 PM EST Wed Nov 23 2016
The main models are in good agreement. The Central Region
initialization can be used with high confidence.
This means it is very probable there will be dry weather Sunday and
rain Monday night and Tuesday. It is too early to be sure just when
rain will start and stop between those times.
Given the background model agreement, expect the temperature
forecast to capture trends well. Individual forecasts may be off by
1-3 degrees depending on the details of what happens.
&&
.AVIATION (Discussion for the 232100Z TAF update)...
Issued at 318 PM EST Wed Nov 23 2016
Tuning was needed for the latest observations, but overall the
earlier forecast is on track. Previous discussion follows.
A combination of drier air moving in aloft and moisture persisting
near the ground will cause widespread LIFR and local VLIFR ceilings
to develop from this afternoon into this evening. Rain should end as
ceilings drop. Ceilings will recover to IFR Thursday morning as
surface dry air slowly moves in.
Visibilities should not decrease to the same extent ceilings
do. They may still be IFR in fog at some places overnight.
Winds are forecast to gradually veer from southeast to northwest.
Speeds should be mainly less than 10 knots.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JK
NEAR TERM...JK
SHORT TERM...JK
LONG TERM....JK
AVIATION...JK
Area Forecast Discussion
National Weather Service Mobile AL
413 PM CST Wed Nov 23 2016
.NEAR TERM /Now Through Thursday/...Upper air map analysis shows a
sharp trof axis moving eastward around 25 knots across the
Mississippi River Valley. Within the trof axis, a surface front was
also positioned in the same areas mentioned above. A north to south
zone of precipitable water values (above the mean) extends from the
Upper Mid-West to the western Gulf. Within this zone, precipitable
water values from 1.1 to 1.4 inches, moving into the Lower
Mississippi River Valley, lies between 130 to 160% of normal.
Satellite trends indicate that clouds will be on the increase and
thicken in the near term as the frontal zone approaches from the
west. Although there is moisture available, a rapid movement of the
better dynamics across the local area and the high level energy
dampening a bit, frontal ascent weakens through Thursday suggesting
showers will be lowering to isolated coverages at best in the near
term. This is already being observed in radar with returns moving
eastward across southern Mississippi and southeast Louisiana. These
trends also noted in high resolution HRRR and 4KM NAM output.
Precipitation amounts look light, mostly less than 5 hundredths of an
inch. There is also a signal in the high resolution NAM12 and the
SREF of showing increased probabilities of developing late night fog.
Visibility could be reduced to less than a mile at times. Overnight
lows in the mid 50s interior to lower 60s coast. Daytime highs on
Thanksgiving Day mostly in the mid ranges of the 70s. /10
.SHORT TERM /Thursday night Through Saturday night/...An upper level
ridge of high pressure will gradually shift eastward over the
southeastern U.S. and western Atlantic Ocean Thursday night into
Friday as a weak shortwave trough translates toward the Ohio and
Tennessee River Valley region. An associated weak cold front will
push southeastward into our forecast area during the day Friday.
Moisture and lift ahead of this boundary will be very limited, but
there may be just enough available to aid in the development of a few
isolated light rain showers early Friday morning. Lows Thursday night
should range from the upper 40s to mid 50s over most interior areas,
with upper 50s to lower 60s expected near the immediate coast. Highs
Friday should warm into the 70s area wide.
Surface high pressure will build from the Southern Plains to the
Mississippi and Tennessee Valley region Friday night into Saturday,
then across the southeastern states Saturday night. No precipitation
is expected during this time frame as a deeply dry airmass settles
into the region. Clearing skies and cooler temperatures are expected
Friday night through Saturday night. Lows Friday night should range
from the lower to mid 40s inland to the lower to mid 50s coast. Highs
Saturday should range from the mid 60s to around 70. Lows Saturday
night trend a little cooler in the mid 30s to around 40 over the
interior to the mid 40s to around 50 near the immediate coast and
beaches. /21
.LONG TERM /Sunday Through Wednesday/...The operational 12Z runs of
the GFS and ECMWF have come into fairly decent agreement in their
solutions with the evolution of the upper air pattern late this
weekend into early next week. Dry weather is expected to continue
across the forecast area Sunday as shortwave ridging aloft builds
from the western Gulf of Mexico to the Great Lakes. Upper ridging
is then forecast to shift eastward over the southeastern U.S. and
into the western Atlantic Ocean early next week as a broad longwave
trough deepens over much of the central CONUS Monday and Tuesday.
Surface high pressure will also subsequently shift from the eastern
U.S. into the western Atlantic early next week as surface low
pressure deepens and lifts northeastward across the northern Plains
and Great Lakes region. A surface cold front should subsequently
advance eastward toward the Mississippi Valley and Gulf Coast states
Monday into Tuesday.
The GFS and ECMWF both show an organized area of convection
advancing eastward toward our forecast area along and ahead of the
cold front sometime during the Tuesday-Tuesday night time frame as a
fairly potent shortwave trough advances eastward toward the
Mississippi and Tennessee Valley region. A low CAPE/high shear
environment will likely be in place over our area ahead of these
approaching features, with MLCAPE values between 250-500 J/KG per the
latest GFS, a developing 45-60 kt low level jet, and increasing
0-1km helicity values between 200-400 m2/s2. It therefore looks like
we will have to monitor for severe weather potential as convection
rolls into the area Tuesday. Otherwise, this system is looking like
it will bring the best chance of rain to our area in a good long
while. We have POPs trending upward to 20-30% with potential for
isolated to scattered warm advection showers Monday-Monday night,
with 50-60% POPs on tap for Tuesday. Rain chances currently appear to
decrease Tuesday night into Wednesday as the cold front moves east of
the region. /21
&&
.MARINE...A weakening front approaches the lower Mississippi River
Valley tonight and begins to slow across the central Gulf Coast
region on Thursday. The front makes passage by Friday morning. A
light onshore flow is forecast thru Thursday with winds shifting to
westerly then northerly behind the front Friday. High pressure builds
back into the Southeast US over the weekend, establishing a light
return flow off the Gulf by later in the day Sunday. A more potent
storm system moving across the plains on Monday, combined with high
pressure over the southeast results in a strengthening onshore flow
and building seas early next week. /10
&&
.CLIMATOLOGY...A lengthy period of abnormally dry conditions has
resulted in worsening drought conditions over the central Gulf coast.
Since September 27th, Mobile Regional Airport went through a bone-dry
spell of 42 consecutive days with no measurable rain and 41 days at
Pensacola before it finally rained again on November 8th. As it
stands to this date since September 27th, 56 days at Evergreen
straight, without measurable rain. Current annual rainfall deficits
stand at between 6 and 9 inches below normal. Drought has worsened
with severe to extreme drought conditions being experienced over the
local area. A more potent storm system impacting the area early next
week brings the most promising rain potential seen in quite some
time, but this system looks to be progressing eastward rapidly
enough as to do very little in placing a significant dent in the
drought. Stay tuned. /10
&&
.PRELIMINARY POINT TEMPS/POPS...
Mobile 59 77 53 76 / 20 10 10 10
Pensacola 61 77 59 77 / 10 10 10 20
Destin 63 76 62 76 / 10 10 10 20
Evergreen 55 78 53 76 / 20 20 10 20
Waynesboro 53 74 47 73 / 20 10 10 10
Camden 55 76 48 74 / 20 10 10 10
Crestview 55 80 53 78 / 10 10 10 20
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
quandary in this forecast discussion centers around if there will
be any or enough breaks in cloud coverage to possibly enhance
diurnal atm instability enough to support not only strong, but
possibly a few severe tstms here and there too. This system should
push thru the mid state region on Wed with some lingering shwrs
behind it.
Temperatures should generally remain above seasonal normal values
thru Fri afternoon. A dry frontal passage on Fri afternoon will
eventually allow cooler air to work into the mid state, with
temperatures closer to seasonal normal values over the weekend.
A warming trend is expected into the first part of next week as
the above mentioned stronger frontal system approaches.
&&
.AVIATION...
18Z TAF DISCUSSION.
Expect rainfall to gradually approach CKV and BNA early this
afternoon and CSV later this evening. Radar trends indicate
minimal impact to VIS and CIGS with the rain, but a transition to
IFR CIGS overnight is expected at all three sites as surface obs
upstream show OVC skies with about 1k foot CIGS. Once the front
passes around daybreak expect light NW winds and VFR conditions.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 52 62 44 63 36 / 50 10 0 10 0
Clarksville 47 60 41 59 33 / 40 10 0 10 0
Crossville 50 60 41 60 34 / 50 20 0 10 0
Columbia 50 62 42 65 34 / 50 10 0 10 0
Lawrenceburg 50 63 42 65 36 / 50 10 0 10 0
Waverly 48 61 40 62 34 / 40 10 0 10 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......31
AVIATION........05
Area Forecast Discussion
National Weather Service Tulsa OK
224 PM CST Wed Nov 23 2016
.DISCUSSION...
The main forecast challenges will be stratus and fog in the short
term, and sensible weather early next week in a gradually evolving
upper air pattern.
Upper system and associated cold front has pushed well to the east
and south of the region this afternoon. A large area of stratus
has persisted over much of the lower Plains in its wake, and has
been very stubborn to clear. The latest vis sat trends show a slow
clearing from west to east and this should continue until evening
before this trend comes to an end. For tonight into the holiday
morning, I have elected to use the experimental HRRR as a guide.
This model appears to be handling the stratus deck pretty well and
it likely has a better idea on the fog potential as well. The
overcast skies have kept temps down today, with cool and
relatively moist conditions in the boundary layer (BL). The
stratus should clear most areas except NW AR by early this
evening. Radiational cooling of the cool and relatively moist BL
will result in the development of at least patchy dense fog by
morning except the far south by morning. Low temperatures may
cool to near or just below freezing at the typical cold spots,
however I`m not expecting any travel troubles from any potential
freezing fog given very warm ground temperatures. As for NW AR,
despite the fact that low clouds are not expected to clear there,
IFR conditions are persisting and thus it will not take much for
stratus to build down into fog as the HRRRX is suggesting. Once
the fog burns off tomorrow, a sw wind and sunshine should lead to
a nice above average day temp wise for holiday festivities.
A progressive upper flow pattern is expected to persist thru the
remainder of this week. Another fast moving wave will pass by to
our north tomorrow evening, and will push another front thru our
area and will knock temps back down for Friday.
The next shortwave trough is expected to organize off the West
Coast this weekend. Due to a merging of the polar and a strong
subtropical jet, this system will undergo cyclogenesis as it lifts
northeast into the Plains late in the weekend. Sunday and Sunday
night will be quite windy and have thus increased winds from the
typically underdone consensus grids. Our area will stay in the
warm sector of the cyclone and thus attention then turns to
moisture return and instability. Model data today seems to be more
aggressive at digging tomorrow`s wave to our north a bit deeper
into the Southeast CONUS this weekend. This should force surface
ridging over much of the Gulf basin and thus only a modified
return of moisture is expected ahead of the system, which will
limit instability ahead of the associated cold front, and thus the
severe potential as well.
An ever strengthening polar jet punching into the Western CONUS
from the NE Pacific will help to carve out deep cyclonic flow over
the western 2/3rds of the nation early next week. Another fast
moving wave will be right on the heels of the Sunday system, on
the tail end of the propagating subtropical jet traveling in this
cyclonic flow. This system is expected to interact with the
stalling front from the Sunday system to produce a band of showers
and storms from N TX up thru the ArkLaTex. The models have not
been consistent from run to run regarding where this band will set
up and thus pops for this forecast will not go any higher than
middle ground.
The longwave trough is expected to lift out by the middle to
latter part of the week, and will lead to a warming trend and
quiet weather to close out the work week.
Lacy
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 35 65 39 61 / 0 0 0 0
FSM 37 65 40 62 / 0 0 0 0
MLC 36 66 41 62 / 0 0 0 0
BVO 31 65 36 60 / 0 0 0 0
FYV 33 61 34 58 / 0 0 0 0
BYV 35 59 39 57 / 0 0 0 0
MKO 35 64 38 59 / 0 0 0 0
MIO 32 62 36 58 / 0 0 0 0
F10 36 65 39 60 / 0 0 0 0
HHW 39 66 42 63 / 0 0 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
LONG TERM....30