Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/26/16
Area Forecast Discussion
National Weather Service Gaylord MI
1004 PM EST Sun Dec 25 2016
.UPDATE...
Issued at 940 PM EST Sun Dec 25 2016
The whole general pattern is playing out fairly well tonight, with
WAA band of mixed precip currently lifting through the GTV Bay
region. We are building the warm layer aloft right now, with the
leading edge of precipitation in the form of snow/sleet and light
freezing rain, and more full melting is likely occurring in the
srn half of the band. The thing is, moisture has seemingly only
periodically been able to reach up into temperatures for ice
introduction to create bona fide "rains". In other words, drizzle
has also been in the picture. The precip has also been more patchy
in nature too, and these things have cut down on overall ice
accumulation. Regardless, there have been reports that roads and
walking surfaces were becoming a little slick around the GTV Bay
region. Snow and sleet was accumulating across western portions of
Chip/Mac counties where reports have come in that things were
getting slick there too. So, these things are playing out
decently.
What the concern is, most all data suggesting higher QPF overnight
than forecast, as deeper moisture and heavier precip is supposed
to fill in ahead of the occluded front that follows our initial
WAA band. This is to coincide with converging southerly winds
ahead of the deep sfc low moving into South Dakota. Looking at
latest WV imagery however, there is a substantial drying aloft in
this region, with only a thin band of showers. So I question the
higher QPF at this point. This is especially true due to RUC
soundings continuing to show moisture barely reaching -10C for
ice. Went ahead and lowered total ice accumulation for the night
with generally less than 0.05" for nrn lower. A longer period of
below freezing temperatures across eastern upper which will be
able to clip the second round of showers with the occluded front
late tonight. Can see maybe 0.15" ice there. To state it again
however, ANY ice accumulation creates very hazardous driving and
walking conditions. Will leave headlines (Advisories) as they are.
Also addressed wind evolution into late tomorrow and tomorrow
night. As the occluded front crosses us tomorrow, there will start
some increased mixing. There will also be better mixing within
the CAA, especially downwind of Lake Michigan. Winds aloft will
continue to howl at 50-60mph just 1500-2000 feet above the sfc.
Have definite concerns to very high wind gusts late tomorrow into
Monday evening before winds slowly subside through Monday night
(although it will still be gusty). Can see 40-50mph in coastal
areas of Lake Michigan weakening to 35mph across NE lower. There
may be a need for a wind advisory for the coastal counties of Lake
Michigan. Be prepared to lock down any loose objects!
&&
.NEAR TERM...(Tonight)
Issued at 321 PM EST Sun Dec 25 2016
...Mixed precip and windy conditions tonight into early Monday...
High Impact Weather Potential...Freezing rain/sleet/snow combined
with windy conditions tonight into early Monday causing hazardous
travel.
Pattern Synopsis/Forecast...Strong surface high pressure center has
reached James Bay late this afternoon...with the ridge axis
extending southward into New England. Deep low pressure continues to
develop to the lee of the Central Rockies. Southerly flow continues
to strengthening across the nation`s mid section between these two
systems...beginning to pump warm moist air thru the Plains and
Mississippi Valley toward the Great Lakes region. Closer to home...
E/SE low level flow off of Lake Huron combined with limited/shallow
over-lake instability and very shallow low level moisture produced
some scattered light lake snow showers this afternoon across
portions of NE Lower and Eastern Upper Michigan. Rest of our CWA
remains dry but mostly cloudy at this hour. As we move into this
evening...scattered lake snow showers will wane with loss of over-
lake instability as WAA ramps up. Still looks like arrival of any
synoptic precip will hold off until after 00Z this evening...
spreading SW to NE across our entire CWA during mid to late evening.
Widespread precip will continue overnight into Monday morning...and
will then begin to peel away Monday afternoon with passage of the
occluded front.
Primary Forecast Concerns...Main forecast issue is the evolution of
precip type throughout this event. Secondary issue is strengthening
wind speeds in response to significant tightening of the pressure
gradient as the low center lifts NE to just north of Lake Superior
by Monday afternoon. Once the column moistens this evening... BUFR
soundings still suggest precip type will be mainly freezing rain
given the prominent and rather deep warm nose that develops aloft
with sharp cooling to well below freezing for several thousand feet
below that warm nose...at least initially. Low levels do gradually
warm to above freezing beginning around 06Z in our far SW CWA and
then gradually progressing NE thru the rest of our CWA overnight
into Monday morning. Last vestiges of freezing rain should end by
12Z across Northern Lower Michigan but will likely hang on until
around 15Z across Eastern Upper Michigan. Still expect ice
accumulation will remain under a quarter of an inch (i.e. under
warning criteria) for our entire CWA...but will need to keep a close
eye on Eastern Upper Michigan where freezing rain will linger
longest. Will keep all Winter Wx Advisories in tact with no
adjustments needed at this time. Will add mention of winds gusting
to 20 to 30 mph within the WSW...with some higher gusts expected
near the lakeshores. As far as temps go...low temps will actually
occur early this evening...with gradual warming of surface temps
throughout the night and thru early afternoon on Monday. High temps
by early Monday afternoon will range from the upper 30s to lower 40s
in Eastern Upper Michigan to the mid 40s across Northern Lower
Michigan. Temps will then begin to fall after 18Z with FROPA.
&&
.SHORT TERM...(Monday and Tuesday)
Issued at 321 PM EST Sun Dec 25 2016
...Post-System Lake Effect...
High Impact Weather Potential...minimal. At this point the snow
amounts for the LES are light to Moderate at best.
Pattern Synopsis/Forecast...As the storm that gave us some of the
freezing rain departs, and is north of Lake Superior at 00z/Tue
moving northeast, the cold air following it moves in quickly with
the 850 mb temperatures already having fallen to -8c by 06z, and
-12c by 12z. The moisture in the 850-700 mb layer is around 80% lake
effect is expected. However, the winds are the complicator in this
case. The wind direction changes from SW to W to WNW during the 12
hours. There will be some enhancement early, post frontal, but
expecting minor to light accumulations. Now there is a concern for
the day on Tuesday as the wind directions remain roughly WNW through
the day, and a dominate band is possible with the still relatively
open lakes. Minor accumulations are expected as the winds begin to
back to the SW again with the moisture beginning to leave, and the
temperatures rising. Temperatures late on Wednesday warm enough to
cut off any lake enhancement, but are still cold enough for snow
with the next clipper to move into the Upper Great Lakes. however,
there is some warm air near the sfc (sfc temperatures get to the mid
30s) which may lead to a rain/snow mix near Lake Michigan in the SW
counties.
Primary Forecast Concerns...The dominate band issue on Tuesday is
the main concern, so that that snow amounts could increase to
moderate to have. However, that may be a low chance possibility as
the ECMWF is showing more of a changing wind direction scenario
which may be right. So have left the idea of light amounts.
.LONG TERM...(Tuesday night through Sunday)
Issued at 321 PM EST Sun Dec 25 2016
High Impact Weather Potential: Minimal. Snowfall is expected through
much of the period, but not currently expecting widespread headline
level accumulations any given day.
Snow chances will persist through the extended period as a pair of
clipper systems transit the region. The initial system should be
arriving by the start of the period Wednesday night, with lake
effect continuing the snowfall into Friday. There may be a brief
break Friday, likely late evening into the overnight, as a narrow
ridge builds into the region. However, it may be too brief to really
stop the inertia of the lake processes so this will likely be
tweaked a bit in the coming days. The second clipper will quickly
follow, arriving Saturday, with another brief round of lake effect
likely behind it.
The narrow ridge of high pressure nosing in between the clippers
could produce some gusty winds as the tightened pressure gradient
combines with cold advection aloft. Temperatures should be near
normal for most of the period, with a bit of a cold shot Friday as
the coldest air of the period filters down behind the initial
system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 654 PM EST Sun Dec 25 2016
...A period of freezing rain tonight with LLWS then the
development of very strong wind gusts late in the TAF period...
Deep low pressure will track from the Dakotas through Ontario this
TAF period. A band of generally light warm advection mixed
precipitation, which includes freezing rain and freezing drizzle,
will swing across the airports between 02Z and 10Z when it exits
APN. Total ice accumulations around 0.05" expected. The warmer air
moving in over cold snowpack will likely lead to a little fog
development. This batch of precipitation will be followed by a
band of heavier rain associated with a cold front, which impacts
the airports late tonight through mainly Monday morning. Winds
over this time will be gusty, veering from east to south. More
importantly is the strength of the LLWS which will climb from
30-35kts currently, to as high as 50 to 60kts late tonight through
most of tomorrow. The air mass will gradually be getting colder
and we will gradually be developing some late day and evening
instability/mixing, mainly downwind of the lakes where we will
also see a few snow showers starting to develop across NW lower.
Again, the more important thing will be the winds. The mixing
doesn`t have to be deep to touch of some significant wind gusts of
40 to 45 knots.
&&
.MARINE...
Issued at 321 PM EST Sun Dec 25 2016
Winds will continue to strengthen this evening in advance of
developing low pressure over the Central Plains. Winds will reach
gale warning criteria overnight...with gale warning conditions
persisting thru Monday (at least) as the low center continues
eastward thru Southern Ontario. Widespread mixed precip will develop
tonight as deep moisture surges northward into Michigan head of the
low. Precip will change over to all rain by Monday morning as temps
warm into the 40s.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY until 7 AM EST Monday for MIZ016>019-
021>024-027>030-033>036-041-042.
WINTER WEATHER ADVISORY until 5 AM EST Monday for MIZ020-025-026-
031-032.
WINTER WEATHER ADVISORY until 10 AM EST Monday for MIZ008-015.
LH...GALE WARNING until 7 PM EST Monday for LHZ345>349.
LM...GALE WARNING until 7 PM EST Monday for LMZ323-341-342-344>346.
LS...GALE WARNING until 7 PM EST Monday for LSZ321-322.
&&
$$
UPDATE...SMD
NEAR TERM...MLR
SHORT TERM...JSL
LONG TERM...ALM
AVIATION...SMD
MARINE...MLR
Area Forecast Discussion
National Weather Service Duluth MN
609 PM CST Sun Dec 25 2016
.UPDATE...
Issued at 609 PM CST Sun Dec 25 2016
A mixture of sleet and freezing rain has moved through most of the
Northland and will continue to lift north through the Borderland
over the next 1 to 2 hours. The precipitation type in the far
north should be mostly sleet or snow but RAP soundings do show
some freezing rain will also be possible. Forecast soundings do
show more warming aloft which may cause the precipitation to
become more freezing rain over as far north as the Range but
especially south of there including northwest Wisconsin. Surface
temperatures will rise some though and that would cause mainly
rain and this is most likely from the Brainerd Lakes east through
Hayward and Park Falls by 2z or 3z. Some of the short term
guidance does bring temperatures above freezing as far north as
KINL, the Iron Range and over most of northwest Wisconsin late
this evening into the early morning hours.
&&
.SHORT TERM...(This evening through Monday)
Issued at 333 PM CST Sun Dec 25 2016
Freezing rain was rapidly advancing northward as of 330 PM, with
freezing rain being reported at nearly every weather observation
site in our southern CWA. Road conditions were already bad due to
extensive freezing drizzle today, but we do expect them to
deteriorate even further during the night.
The main focus for tonight will be the potential for significant
icing, as well as the potential for snow and ice in the north.
Contemplated upgrading our southern zones to a winter storm
warning, but the high resolution models generally do show that
tier of counties rising to freezing or a little above overnight.
The only concern with that is that pavement temperatures are still
quite low, in the 20s to around 30 for the most part.
Forecast soundings indicate the potential for freezing rain for
much of the night, especially in the south. The precipitation will
then switch to snow from northwest to southeast as the night wears
on. KINL should see the most snow from this event, with mainly 4
to 8 inches of total snow accumulation. Much less is expected in
the south, where a majority of the precipitation will be ice.
There are two main bands of precipitation currently moving across
the Upper Midwest. The first was lifting north of the Twin Cities
as of 345 PM. The second was more of a northwest to southeast
oriented band. This band will lift northward, with precipitation
filling in between the first and second band. The result will be
locally heavy precipitation, and major icing. Trees and power
lines are obviously a major concern, as they may topple due to the
weight of the ice, causing power outages.
Conditions will improve in terms of precipitation on Monday, but
snow showers will sweep across the entire CWA. The big story on
Monday will be intense westerly winds, gusting over 40 mph at
times.
.LONG TERM...(Monday night through Sunday)
Issued at 333 PM CST Sun Dec 25 2016
A lingering surface trof will be located over western Lake Superior
Monday night. Meanwhile, a series of short waves will move through
the Dakotas and Minnesota. This will be enough to generate some snow
showers over much of the area in the evening, then restricted to the
international border overnight. Lake effect snow showers are
possible over the snowbelt of northwest Wisconsin. However, the wind
direction will be west northwest which is not favorable for
accumulation. This lake effect situation prevails through Tuesday
while surface high pressure covers the rest of the forecast area. A
surface low is progged to move through southern Manitoba Tuesday
night accompanied by an upper short wave trof. The best forcing will
occur late Tuesday night and right along the border and have pops to
represent these features. The surface low lifts into northwest
Ontario on Wednesday and drives a front through the region. The
upper trof is aligned with the surface front and the additional
forcing leads to pops over much of the area. Little snow
accumulation is expected. Wednesday night and Thursday finds a
closed upper low moving through Ontario with northwest flow aloft to
the surface. Embedded pieces of energy will cruise over the region
which warrants having some pops. Due to the speed of these impulses,
not much accumulation is expected. However, lake effect snow
processes will be in play over northwest Wisconsin which may lead to
some minor accumulations. The lake effect snow chances continue
Thursday night into Friday morning along the snowbelt of northwest
Wisconsin, but gradually diminish as dry air from approaching high
pressure begins to reduce the potential. On Friday, the ECMWF has
high pressure over the region, while the GFS has the next surface
low/upper trof approaching and bringing light snow to the
international border. Used a consensus approach to pops, which
places them along the Canadian border. The model differences become
more pronounced Friday night and Saturday with the handling of low
pressure moving through the western Great Lakes region. Used a
blended approach to pops to account for these issues.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 609 PM CST Sun Dec 25 2016
Widespread sleet and freezing rain covered most of the Northland
with the exception of far northern Minnesota, and a mix of sleet,
snow, and freezing rain will move across the rest of far northern
Minnesota as well over the next 1 to 2 hours. Conditions will
mostly be IFR or low MVFR through the TAF period. The precipiation
should diminish in intensity from south to north mainly after 06Z.
Surface temperatures are expected to warm some as the evening
progresses with some of the short range guidance bringing
temperatures above freezing to KINL and into the Iron Range.
Precipitation type will continue to be a challenge but expect the
freezing rain/sleet in the far south to go over to rain with
mainly sleet or snow along the International Border. However, even
in that area there could be some freezing rain for a time.
Strong easterly winds will veer overnight south to southeast then
to west to southwest by mid Monday afternoon and be strong then as
well.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 27 30 8 16 / 100 60 10 10
INL 25 31 5 12 / 100 90 30 10
BRD 25 25 8 18 / 100 60 10 0
HYR 30 31 11 19 / 100 40 20 10
ASX 32 34 15 19 / 100 50 20 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 9 AM CST Monday for WIZ001>004-
006>009.
MN...Ice Storm Warning until midnight CST tonight for MNZ025-033-034.
Winter Storm Warning until noon CST Monday for MNZ010-018-019-
026-035-037.
Winter Weather Advisory until 9 AM CST Monday for MNZ036-038.
Winter Storm Warning until 6 PM CST Monday for MNZ011-012-020-
021.
LS...Gale Warning until 10 PM CST Monday for LSZ121-140>148.
&&
$$
UPDATE...Melde
SHORT TERM...DAP
LONG TERM...GSF
AVIATION...Melde
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
914 PM CST Sun Dec 25 2016
.UPDATE...
Removed showers for the rest of this evening across all areas.
Also, adjusted WX/PoPs grids from midnight tonight to early Monday
morning (12Z). Latest NAM and HRRR models and GFS LAMP guidance are
showing better chances for showers later Monday morning into the
afternoon hours. They do agree on patchy light drizzle and fog
overnight into Monday morning as winds decrease 10 MPH or less.
A weak frontal boundary is forecast to move across the Hill
Country Monday morning and stalls over the area. Best rain
chances are mainly along and east of Highway 281 Monday afternoon.
Not expecting a whole lot of rainfall with this system, however,
some locations across the Hill Country and eastern counties could
get one quarter to one half inch.
&&
.PREV DISCUSSION... /ISSUED 540 PM CST Sun Dec 25 2016/
AVIATION...
VFR conditions are currently prevailing at the area airports this
afternoon, but should lower back into MVFR levels as ceilings
lower in the next few hours. Should see the ceiling heights reach
IFR around midnight before lowering into LIFR by daybreak. There
will also be the potential for fog in the morning hours as well.
Will prevail 1 statute mile at the I-35 sites for now, but
the visibility could drop lower and will reassess with the 06z
TAF package. A weak frontal boundary will approach the area by
the morning hours before stalling which should not only aid with
the fog potential but also serve as a focus for some scattered
light rain or showers. Will mention vicinity showers for most of
the morning and the early afternoon hours to account for this
threat.
PREV DISCUSSION... /ISSUED 258 PM CST Sun Dec 25 2016/
SHORT TERM (Tonight through Monday Night)...
This afternoon, winds have exceeded expectations in some spots,
with observations showing gusts as high as 40+ mph. Sustained
winds have stayed mostly below the sustained criteria for a wind
advisory but gust potential, likely due to low level winds being
mixed down to the surface, has been impressive. Guidance suggests
this to finally wane in the next few hours.
A weak frontal boundary was observed at 2030Z from central Val
Verde north to just east of San Angelo. Satellite trends indicate
that capping is still holding strong across the region as only a
thin layer of disturbed CU is being observed along the front
itself. The hi-res suite of models continues to say bah-humbug to
QPF overnight as well. Towards morning, convergence along the
front with a little better moisture across the eastern CWA may be
enough to generate a but more substantial QPF development, thus
have kept PoPs only slight chance through 06Z and increased after
midnight through Monday. Models are showing capping to erode
tomorrow enough to produce some isolated thunderstorms during the
afternoon as well so have included this in the WX grid for Monday.
LONG TERM (Tuesday through Sunday)...
The focus of the long term will be the wavering of the stalled
frontal boundary to the north. NAM and some hi-res models do want
to bring the front, or at least the wind shift, through the CWA
but this has been inconsistent with global models. So have
maintained the thinking of a stalled boundary through mid week.
This will continue to be the focus for PoP chances through
Wednesday.
The next cold front is progged in pretty good agreement between
the ECMWF and GFS now for Thursday morning around 12Z. As of the
12Z model runs, the front should be mostly dry, with PoP chances
staying mostly in CRP`s neck of the woods. This will cool the
area off however about 20 degrees from the mid 70s that will be
experienced thus far.
Long range models are coming somewhat in line with a progressive
shortwave passage for New Year`s weekend that may complicate
outdoor activities on New Year`s eve possibly. For now, will leave
out details as timing discrepancies will dictate the level of
impact. More to come on this with future forecasts.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 66 76 59 67 59 / 30 50 40 20 10
Austin Bergstrom Intl Airport 66 77 59 67 60 / 30 60 40 20 10
New Braunfels Muni Airport 66 77 60 70 60 / 20 50 40 20 10
Burnet Muni Airport 61 70 54 64 56 / 30 40 40 20 10
Del Rio Intl Airport 59 70 58 68 59 / 10 20 30 30 10
Georgetown Muni Airport 64 73 56 65 58 / 30 50 40 20 10
Hondo Muni Airport 64 76 62 72 61 / 10 40 40 30 20
San Marcos Muni Airport 66 77 60 70 60 / 20 60 40 20 10
La Grange - Fayette Regional 68 79 63 72 62 / 30 60 40 20 10
San Antonio Intl Airport 67 76 61 70 61 / 10 50 40 30 20
Stinson Muni Airport 67 76 62 72 62 / 10 50 40 30 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Hampshire
Synoptic/Grids...17
Public Service/Data Collection...30
Area Forecast Discussion
National Weather Service Fort Worth TX
951 PM CST Sun Dec 25 2016
.UPDATE...
Another quick update this evening to remove thunder wording from
the gridded forecast products and to make some small tweaks to PoP
trends. The vigorous mid-level cyclone continues to rapidly
rotate into North Dakota late this evening, taking any dynamics of
note with it. ACARS soundings reveal stout capping inversion(s)
remain centered around 700 mb. Can`t rule out a clap or two of
thunder, but the threat for thunderstorms appears low overnight.
As expected earlier, we`re seeing some southwestward development
of shower activity, but coverage south of I-20 looks to remain
just isolated to perhaps scattered, with better precip chances
east of I-35 and north of I-20 overnight. Might also see some very
patchy visibility reductions across our far southeastern zones
tonight, but any coverage appears too low to mention in the worded
forecasts at this time.
Carlaw
&&
.AVIATION...
/ISSUED 547 PM CST Sun Dec 25 2016/
/00Z TAFs/
Early challenges include timing of pre-frontal surface trough and
cold front, along with showers/isolated tstorms and cigs overnight.
Currently, a line of weak showers was associated with a slow-
moving pre-frontal surface trough to the west of I-35. As
expected the past several days, an upper low continued to
negatively rotate northeast from the Central High Plains toward
the Upper Midwest. A strong elevated mixed layer (EML) was
keeping any convective activity minimal at this point. Meanwhile,
both the surface trough and cold front are slowing down as the
upper level energy continues moving northeast further away from
the area.
As such, have delayed the veering of surface winds at all airports
by 3 to 6 hours, with VCSH noted through much of the night at DFW
terminals, while delaying the same trend at Waco by 6 hours or
more. All sites should start off with southerly winds around 15
kts, slowly veering and becoming southwesterly behind the surface
trough after midnight at DFW area terminals, to after sunrise at
Waco. Actual FROPA with the cold front should occur by midday
Monday and after at all terminals with winds shifting northwest
near 10 kts.
As for tstorm potential, think the high-resolution models are
struggling with the intensity of the EML (cap) and possibly
overdoing convective development along the pre-frontal trough
later this evening. With nightfall upon us, despite slightly
better moisture and instability east of I-35, feel cooling of the
boundary layer along with a residual EML(cap) should minimize
tstorms and lighting to an occasional occurrence, but not
widespread. As such and with lacking confidence in the models,
have only introduced VCSH at all terminals until area radars and
our 00Z upper-air indicates otherwise. Will be monitoring closely
for lightning throughout the evening.
05/
&&
.UPDATE...
A very narrow band of showers--barely 10 miles across--extends
along a southwestward-arcing cold front from eastern Kansas into
portions of Central Oklahoma, to its southern terminus in Cooke
County this hour. Hardly any lightning is occurring with this
line, with just a few CG strikes and in-cloud flashes noted near
the Oklahoma/Kansas border, which is clearly indicative of the
ongoing stout capping which is stunting vertical convective
development. The 00Z FWD sounding, coupled with recent ACARS
profiles, reveals the capping inversion from this morning had been
lifted and weakened somewhat. RAP forecast soundings indicate a
gradual lifting of the 750-650 mb layer may continue this evening,
but any effects on the aformentioned inversion should wane as
forcing associated with the parent mid-level cyclone races off
into the Dakotas. Finally, surface winds out ahead of the cold
front are slowly veering, which will further limit low-level
convergence along the front tonight.
High-resolution guidance suggests that some southward shower
development will be possible this evening as the cold front
potentially taps into a bit more buoyancy as it continues east.
Based on trends, almost pulled thunder completely from the
forecast, but opted to continue isolated wording given the above-
mentioned potential lifting of the cap. Either way, effects from
this Christmas cyclone look to remain quite limited across North
and Central Texas.
Made a few tweaks to the gridded forecast, mainly to adjust PoP
trends based on radar and high-res guidance, and to slow the
eastward progress of the front as forcing continues to leave the
southern end of the front behind. Updates have been transmitted.
Carlaw
&&
.PREV DISCUSSION... /ISSUED 239 PM CST Sun Dec 25 2016/
...DFW and Waco both tie their record high temperature for
Christmas day (78 degrees) and both could break it with a little
more heating left today...
A weak cold front will continue to move across North and Central
Texas late this afternoon and bring a few showers and isolated
thunderstorms along with breezy west winds behind the front.
Strong and gusty south winds will also continue ahead of the front
with sustained wind speeds between 20 and 30 mph and some gusts
around 40 mph. We will keep a wind advisory in place for the
western two thirds of the forecast area through 6 PM. After
sunset, wind speeds will quickly decrease with boundary layer
decoupling and a weakening surface pressure gradient. Most areas
will see little if any measurable rainfall this evening and if any
location does get a thunderstorm it will only produce occasional
lighting and brief moderate rainfall.
The cold front will stall across the southeastern zones tonight
and will continue be a source of lift for showers and isolated
thunderstorms. The front will remain nearly stationary Monday
through Tuesday continue to bring a chance of rain and isolated
thunderstorms to the southeast half of the forecast area as
moisture is lifted over the dome of slightly more dense air.
Low level moisture will return beginning on Tuesday night in
response to a developing lee trough across the Central High
Plains. This will result in mild temperatures for late December
with morning lows Wednesday in the 50s and 60s and highs
Wednesday afternoon in the 70s.
Another cold front will move across North and Central Texas
Wednesday night through Thursday. The front will bring cooler and
drier air. At this time it appears that large scale forcing and
deep moisture will be absent, therefore the front should come
through precipitation free.
The dry and cool air will remain in place through Thursday night
but low level moisture will quickly return Friday in response to
an approaching low pressure system. Energy associated with this
system will bring a chance of showers to the entire region
Saturday with showers and some storms lingering into New Years
Day.
79
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 58 67 48 61 53 / 40 10 10 10 10
Waco 62 68 53 62 55 / 30 20 40 20 10
Paris 59 68 46 61 51 / 50 20 10 10 10
Denton 53 66 42 61 50 / 40 10 10 10 10
McKinney 58 66 44 61 52 / 50 10 10 10 10
Dallas 59 68 50 62 55 / 40 10 10 10 10
Terrell 62 68 50 62 54 / 50 20 20 10 10
Corsicana 63 68 55 63 57 / 30 30 40 20 10
Temple 63 70 54 64 56 / 30 40 40 20 10
Mineral Wells 50 66 43 62 50 / 30 10 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
05/90
Area Forecast Discussion
National Weather Service Hastings NE
738 PM CST Sun Dec 25 2016
.SHORT TERM...(This evening through Monday)
Issued at 704 PM CST Sun Dec 25 2016
Updated the forecast this evening to accoundt for very strong
transfer of wind to the surface, wrapping around a low located
just to the northwest of the CWA. Issued a High Wind Warning for a
most of our Nebraska counties this evening. The RAP seems to have
a decent handle on the area of strongest wind gusts, if not the
actual speeds.
.LONG TERM...(Monday night through Sunday)
Issued at 233 PM CST Sun Dec 25 2016
The weather should calm down for the upcoming work week. We
remain in northwest flow with a weak mid level wave sliding
through Tue night. Am not expecting precip or a big change in
temps with this system.
Going into next weekend, the EC is progging a little bit deeper
upper trough approaching from the southwest which could cool thing
off a little and bring at least a slight chance of precip Sat night
into Sun night. 00Z run did have some QPF in our CWA, but the 12Z
run has trended a little further south and has us dry. Meanwhile the
GFS is similar with a trough during that time and is pointing to at
least a chance for precip. That is a ways off and will just need to
monitor for now. In the meantime, enjoy high temps in the 40s and
maybe even some lower 50s in the southern CWA. Again this is 10-15
degrees higher than what it should normally be for this time of
year.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday evening)
Issued at 704 PM CST Sun Dec 25 2016
Wind will be the issue tonight. Sustained and wind gusts this
evening at the surface, and low-level wind shear throughout the
night. Wind is howling on the back side of a low, located to the
northwest of the terminals.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...High Wind Warning until 9 PM CST this evening for NEZ039-040-046-
047-060>062-072>075-082>085.
High Wind Warning until midnight CST tonight for NEZ041-048-049-
063-064-076.
KS...None.
&&
$$
SHORT TERM...Heinlein
LONG TERM...Ewald
AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
930 PM EST Sun Dec 25 2016
.SYNOPSIS...
High pressure centered near New England will ridge into the forecast
area into Monday night until a mild cold front pushes through on
Tuesday. Dry and warm high pressure returns briefly Wednesday...with
a fairly strong cold front crossing the area on Thursday.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 925 PM: Increasing upper ridging stretching from the Southeast
to the Great Lakes has brought with it a corresponding increase in
thicknesses, despite the confluent flow aloft over Canada and New
England which has allowed a surface high to dam down the eastern
slopes of the Appalachians. Weak isentropic lift will occur atop
the high overnight, allowing low stratus to expand to blanket
essentially the whole CWFA. Once the stratus sets up, expect it to
remain generally in place through the period with only slow lifting
during the day Monday. Light drizzle is likely to fall out of the
deck, but measurable precipitation is looking increasingly unlikely;
00z NAM is already proving overdone in that department and, notably,
the HRRR is nearly completely devoid of QPF overnight. I backed
off PoPs a bit further with this update. Some fog is expected to
develop, and hi-res model depictions suggest it may become locally
dense, though if precipitation is minimal the low ceilings may
prevent that. Also I revised min temps upward a bit on account of
the clouds and less potential for evaporative cooling.
The parent high moves offshore on Monday but as is commonly the
case residual cool pool remains dammed up against the southwest
mountains, with the cloudy and cool(er) conditions remaining. Right
now have max temps tomorrow pretty close to seasonal normals but
it`s possible that might be a little on the warm side. But overall
little change and not much of a diurnal trend (once the moisture
sets in) through the end of the period. The dismal and dreary
conditions will be a big change from what we`re seeing today.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 200 PM EST Sunday...The upper-level flow will be nearly zonal
across the CONUS for the start of the Short Term, then a long wave
trough will begin to dig across the center of the country by late
Wednesday. The resulting flow will allow a cold front to lay over
the area from the NW on Tuesday, and stall out across the I-20
corridor to our south on Wednesday. The 850 mb flow will persist out
of the west, backing to SW late on Wednesday. This will result in
the main rain chances on Tuesday being confined to the NC mountains,
especially along the TN border, where upslope lift should help.
Models have slight chance to mid chance east, but confidence is low,
given a developing downslope flow. Dry air should filter in behind
the front on Wednesday, drying things out. Temps will remain well
above normal in this flow regime, with little change in thicknesses.
Depending on how much mid-level cloud cover there will be, portions
of the Piedmont may push into the upper 60s to lower 70s both days.
Lows will be nearly 20 degrees above normal Monday night, and only
10-15 degrees above normal Tuesday night.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 230 PM Sunday: the medium range is an attempt to blend
together the GFS and ECMWF which vary in terms of precip coverage,
amount, and timing through most of the period. There are two systems
to deal with. The first situation develops Wednesday night and
Thursday morning with isentropic lift and moisture return ahead of a
surface front to the west. The ECMWF develops much more precip than
the GFS and even has a wave moving along the boundary Thursday
morning. The fcst will lean a bit more in the direction of the
wetter ECMWF with what should be a moisture tap from the Gulf ahead
of the front. Fortunately temps will keep this all liquid. The upper
pattern amplifies late in the week as a large closed upper low moves
across eastern Canada and pushes a deepening upper trof axis across
the region on Thursday night. This will drive colder air down from
the NW behind a cold front and might give us our best shot yet this
season of some NW flow snow showers near the TN border. Precip
ramps back up into the chance range in the usual places Thursday
night and Friday morning. The GFS is generally favored with this
scenario, and this is by no means certain, but we could be looking
at some snow accumulation by Friday morning in the NW flow upslope
places of the nrn mountains of NC. After that, the upper pattern
should remain progressive with the trof axis swinging off the east
coast on Friday and Friday night with an upper/sfc ridge moving in
from the west. That should give us a period of fair weather to start
the weekend. Timing becomes more of a problem with the next system
expected later in the weekend. The latest guidance suggests
slowing down the approach of another front on Saturday and the
forecast has a trend in that direction. Precip chances do not start
to increase until Saturday afternoon as moisture arrives from the
SW. We should be under a broad SW flow Saturday night with warm
advection taking hold in the overnight hours if the model scenarios
are correct. With that in mind, the new fcst favors the warmer
guidance but does not get into details of non-diurnal warming just
yet. Suffice to say there is a good chance of some high elevation
snow if the timing holds, but think most of the precip will be
liquid as there isn`t much to hold any cold air in place and partial
thicknesses are fairly warm. The precip chances will ramp up into
likely on Sunday with the next front approaching from the w/nw.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Cold-air damming is in place over the region
and will provide a source of low-level isentropic lift through the
period. Expect low VFR to MVFR cigs (already over KHKY) to expand
to the remainder of the area this evening. Guidance does not seem
to be handling the stratus well so far, similar to how it responded
to the stratus in the previous weak wedge. Best consensus on IFR
is along the Blue Ridge and areas south; this suggests prolonged
IFR at KHKY/KGSP/KGMU/KAND, and for a shorter period at KAVL. KCLT
looks most likely to bottom out at low MVFR. Areas of -DZ and BR,
perhaps joined by a few pockets of -RA, will be associated with
the low deck overnight and in the morning. Except for KAVL, which
stays in SE quad due to damming and mountain effects, light NE to
ENE winds will continue. Winds do veer into SE quad late in the
period at KCLT.
Outlook: Another front and associated moisture will approach from
the west on Tuesday. Brief mid week drying is expected, but with
moisture returning late week with yet another front.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT Med 70% Med 69% High 94% High 100%
KGSP Med 75% High 87% Med 74% Med 65%
KAVL Med 79% High 80% Med 70% High 100%
KHKY Med 69% Med 72% Med 60% Med 70%
KGMU High 80% High 86% Med 67% Med 64%
KAND High 84% Low 54% High 84% High 96%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...TDP/Wimberley
SHORT TERM...ARK
LONG TERM...PM
AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Louisville KY
907 PM EST Sun Dec 25 2016
.Forecast Update...
Issued at 905 PM EST Sun Dec 25 2016
Visibilities have been naggingly slow to improve on the southern
edge of the fog/low stratus deck. Latest GOES-R LIFR (Limited
Instrument Flight Rules, or less than 500` ceilings and 1 mile
visibility) probabilities indicates the higher probs are shifting
northward, with the clearing line at 0130Z running from Tell City,
IN to FTK to LEX. Webcams at LEX did briefly show that improvement
as mentioned below before tanking again. They now are improving
again...with the latest ob at KLEX verifying it at 2.5 mile vsby.
Part of the reason for the slowdown would be that with the advection
of warmer air also came an increase in dewpoints, keeping the
surface layer saturated.
Mixing at and just above the surface should commence soon with
increasing winds ahead of our next cold front...helping to scour out
the fog from south to north. RAP vertical wind profile indicates 30
knot winds at 1000 feet by the 03-04Z time frame. Latest KLVX VWP
indicates winds at 3000 feet increasing in the past hour to 30
knots, so these winds will descend soon. Thus timing for the end of
the Dense Fog Advisory at 05Z still looks good.
Issued at 720 PM EST Sun Dec 25 2016
Webcams in Lexington are starting to improve, as high-res models
indicated would happen. Will continue to monitor webcam and
automated observations for trends and may be able to trim off a row
of counties from the southern edge of the Dense Fog Advisory between
8 and 10 PM. Had a few reports from locations farther south in
Kentucky, where the higher dewpoints are advecting in. Despite this
moisture, expect stronger winds to start kicking in as the night
progresses, which should keep things mixed enough for further fog
formation.
Issued at 515 PM EST Sun Dec 25 2016
More webcams are showing the worst of the fog deck settling down to
the surface. Based on worsening trends in the CONSShort model
mentioned below, as well as collaboration with neighboring offices,
decided to pull the trigger on a Dense Fog Advisory for southern
Indiana and north Central Kentucky. Will likely be able to drop the
southern parts of the advisory in the next 2-3 hours, as the warm
front lifts north. Will handle that with future updates.
Issued at 425 PM EST Sun Dec 25 2016
Webcams around Lexington show the fog is getting worse, as the
stratus deck at several sites drops down. This is a localized
phenomenon as other sites around Lexington appear to be continuing
with just low stratus and fog in the 1.5-4 mile range. Did extend
the special weather statement we had out for patches of dense fog
and issued a graphicast with webcam imagery. CONSShort model
handling the visibility lower pocket location well, with mins of
under a mile from Shelbyville to Lexington. According to this
model, the pocket should shift northward to Henry/Oldham and
northern Scott counties early this evening and then developing more
in our southern Indiana counties this evening. Will continue to
update with SPS`s for locations as the afternoon/evening continues.
&&
.Short Term...(This evening through Monday night)
Issued at 305 PM EST Sun Dec 25 2016
Warm front drifting ever so slowly north across the region, keeping
frontal fog across our north KY and south IN counties this hour.
Southern edge of clouds now into southern KY this hour, and record
warmth is now occuring at BWG. In fact, there is a spread of 25
degrees from south to north across our forecast area! As the warm
front pushes north this evening, it will pull the rain chances and
fog north with it, to north of our region by early/mid evening.
The dryness will be brief however as a vigorous cold front, now over
the Central Plains, approaches our area. Our southwest IN counties
may see rain chances in the morning, but by afternoon those chances
move to the I-65 corridor and reaching the I-75 corridor by late
afternoon. Expect breezy southerly winds ahead of the front,
bringing warm temperatures for the day after Christmas.
Near max precipitable waters for this time of year will surge
through ahead of the front, meaning a good areawide soaking. Expect
rainfall totals by Tuesday morning could go up to an inch in a few
spots.
.Long Term...(Tuesday through Sunday)
Issued at 305 PM EST Sun Dec 25 2016
Precip shield should be east of the region Tuesday morning, as high
pressure builds in from the west. That high should move over the
Commonwealth Tuesday night, setting up a nice spread of temperatures
from urban locations to our cold valley spots. That high should
shift east of the region Wednesday, setting up a weak southerly
flow. The 12Z Euro continues to paint to large a QPF field, a
pattern it has shown several times the last few weeks with mid-range
forecasts, compared to the drier NAM/GFS/GEM forecasts. Thus will
continue with lower chance pops for Wednesday.
The rest of the work wee will be dominated by a large scale trough
crossing the northeast quarter of the U.S. With that Euro in mind as
the early outlier, the models still have some timing differences on
when pops come in here as that crossing occurs. The blended solution
peaks it Wed. night and this seems a good fit. Given a good
southerly wind ahead of this system, will keep the precip type as
rain. As the trough heads east, our Bluegrass counties could get a
glancing blow of light snow Thursday afternoon and night, but think
the more likely solution will keep that moisture just north of that
area, into southern OH and far eastern KY.
For the weekend, the GFS/GEM both bring a front into the Midwest
Saturday afternoon, with precip chances persisting into Sunday as
southwest flow aloft is slow to shift east.
&&
.Aviation...(00Z TAF Issuance)
Issued at 610 PM EST Sun Dec 25 2016
Fog has gotten worse at the SDF/LEX terminals the last few hours,
but conditions should improve soon as a warm front south of those
locations lifts northward. A low-level jet will develop over all
sites tonight, with winds getting to around 40 knots 1000 feet up.
These winds will translate down to the surface during the day
Monday, as a cold front approaches. This front will bring a return
to lower (though not as low) ceilings as well as rain chances late.
&&
.Climate...
Issued at 247 AM EST Sun Dec 25 2016
A warm front will slowly drift northward today, ushering in very
warm air for this time of year. The warm air will stay in place
through Monday before a cold front brings more seasonable conditions
back to the region Tuesday.
Louisville Records:
December 25 record high: 68 in 1893
December 26 record warm low: 55 in 1971
December 26 record high: 70 in 1942
Lexington Records:
December 25 record high: 70 in 1982
December 26 record warm low: 52 in 1971
December 26 record high: 71 in 1942
Bowling Green Records:
December 25 record high: 70 in 1982
December 26 record warm low: 56 in 1904
December 26 record high: 73 in 2015
&&
.LMK Watches/Warnings/Advisories...
IN...Dense Fog Advisory until midnight EST /11 PM CST/ tonight for
INZ076>079-083-084-090>092.
KY...Dense Fog Advisory until midnight EST tonight for KYZ025-030>037-
040>043.
&&
$$
Updates...RJS
Short Term...RJS
Long Term...RJS
Aviation...RJS
Climate...13
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
921 PM CST Sun Dec 25 2016
.UPDATE...917 PM CST
Just some minor tweaks to hourly temps in the near term with the
warm front just to our south, but temperatures (and dewpoints) are
in the 40s across central Illinois (and just on our doorstep) and
the 50s in southern Illinois, with concerns on the extent of dense
fog.
There is a corridor of mid 40s dewpoints along and just ahead of
the warm front where more prevalent lower visibility fog is
located along a NW to SE axis, and in this area 1/4mi to 3/4 mi
visibility exists. Farther south in Illinois the dense fog has
been longer lasting, whereas when you get farther north it has
only been a shorter period of time. The warm front is going to get
a more significant push in the coming hours, so expect
visibilities to be heading downhill soon. Localized dense fog,
which has already been reported in some areas, may become more
prevalent. Graphical nowcast is handling the situation and will
likely put an SPS or Dense Fog Advisory after assessing the
length of time with the lower vis closer to our area. With the
passing showers and increased wind it may be harder to maintain
the dense fog for an extended time though will monitor.
There are also some showers out ahead of the main relatively
narrow line of showers across IA/MO ,captured well by the 4km NAM,
so expect some lighter rain in the coming hours. There is some
lightning along the leading southern edge of the line. MUCAPE from
the RAP still shows this ribbon sliding through our area, though
weaker on the northern end of the line, so SChc thunder seems a
reasonable thing to hang onto.
Regarding tomorrow`s winds, deep mixing is still possible with the
dry punch behind the front and undirectional wind profile in the
afternoon. NAM depicts 3 hr pressure rises of 4 mb which is not
off the charts but not bad. The better gradient is north so will
let the mid shift take a look but it will indeed be windy tomorrow
afternoon.
KMD
&&
.SHORT TERM...
222 PM CST
Through Monday...
Primary concern in the near term is obviously the powerful storm
system over the Northern Plains and its impacts on our area the
next 24 hours.
Broken band of scattered showers will continue to lift north
across the area late this afternoon into early this evening, with
greatest coverage and even the potential for a thunderstorm
confined to western most CWA. In the wake of this band of showers,
looks as though there could be a long break in precip other than
potential for drizzle to develop as warm front approaches or
perhaps a few widely scattered showers. The break in the precip
should come to an end overnight as strongly forced band of showers
and perhaps an isolated thunderstorm arc northeast across the area
in advance of the associated cold front. These showers will likely
linger over eastern CWA Monday morning before impressive dry
intrusion with this system comes plowing into the area Monday.
As surface warm front approaches from the south tonight, looks for
CIGs/VSBYs to lower with potential for locally dense fog to
develop. Always a challenge determining how widespread of a
problem fog will become in these type of scenarios, threat for
widespread very dense fog certainly exists, but is far from high
confidence. Will brief oncoming evening shift regarding these
concerns and allow them to monitor and hoist a dense fog advisory
when/if it becomes clear dense fog will become a problem. Once the
warm front passes, CIGs should come up and visibilities improve,
so any dense fog that does develop this evening would likely mix
out from the south overnight as warm front moves north.
Speaking of the warm front, temps should largely hold steady or
maybe inch up a degree every couple hours the rest of the
afternoon and into the early evening in advance of the warm front.
Then later this evening and overnight the warm front will quickly
move north across the area allowing an unseasonably warm and
moist air mass to surge north. Temperatures will likely respond
accordingly with temps likely rising into 50s across most, if not
all, of the area before morning with 60F possible southern CWA.
Our brush with unseasonable warmth will be brief, lasting into
early Monday morning before temps begin steadily falling by late
morning and continuing the fall into the afternoon. By evening
temperatures should range from the mid-upper 30s northwest CWA to
mid-upper 40s far SE where the cold FROPA will be later and temp
drop a bit slower.
Skies will clear out during the day as the cyclone`s low-mid
level dry intrusion surges into the area. While the storm will be
occluding and beginning to fill, gradient will be quite strong
still and our area will be in the classic high wind corridor of
the cyclone where low/mid level wind fields marry with subsidence
and deepening mixing in the CAA regime likely promoting very
strong southwesterly winds. Certainly plausible that winds could
gust to 40 mph at times tomorrow, for now plan to keep winds just
below advisory criteria, but it could end up being close and
something for later shifts to at least ponder.
Izzi
&&
.LONG TERM...
222 PM CST
Monday night through Sunday...
Pattern looks to transition to a more zonal flow through mid week
with a robust clipper-like system passing well to our north mid
week. Track of the clipper favors little chance of any precip, but
strengthening southerly winds in the WAA regime should send temps
climbing solidly into the 40s Wednesday. NAM continues to struggle
with temps where it perceives even the tiniest bit of snow cover
will exist, so trended blended guidance higher closer to the
warmer EC/GFS guidance. Still think that these temps could be
conservative over about the south/southeast 2/3rd of the CWA where
snow cover should largely be wiped out tonight/Monday. Wouldn`t
even rule out 50F for highs far southern CWA.
The clippers trailing cold front will move through Wednesday night
ushering in a much colder air mass (closer to normal). As upper
trough digs southeast into the area Thursday, cold air
stratocumulus deck will filter into the area with potentially
enough forcing to squeeze out some flurries and perhaps even a few
snow showers.
Next clipper is fast on the heels of the midweek clipper and like
its predecessor it should track north of the area allowing for
healthy warm air advection to send temps climbing again. Medium
range models are struggling with the details next weekend as
southern stream energy potentially brings some precipitation to
the area as well. Kept pops in the chance category given the
uncertainty and while current models would tend to favor mainly
rain, the variability in the models suggest there could be
changes and opted to keep mainly rain/snow mention in the grids.
Izzi
&&
.AVIATION...
For the 00Z TAFs...
555 pm...Multiple forecast concerns this period with vis/cigs the
main concern through sunrise Monday morning.
A warm front over southern IL will lift north across the terminals
overnight. As it lifts north and more moist air spreads over the
cold ground/snowpack...expect visibilities to continue to lower.
There remains some uncertainty regarding how low the vis will drop
but widespread vis under 1sm looks on track and will likely drop
to 1/2sm or less in many locations with dense fog certainly
possible. Cigs will also trend down during this time period.
A band of rain...currently moving across western IA...will continue
moving east overnight and spread across the terminals in the
predawn hours. Once this precip arrives...vis should improve to at
least 1-2sm with steady improvement then expected through sunrise.
Eventually...cigs will begin to lift and should scatter out shortly
after sunrise.
East/southeast winds will gradually become southerly overnight and
then turn to the southwest Monday morning. Speeds will remain in
the 12-16kt range for much of that time period with periods of
higher gusts...especially overnight with the rain. Winds will then
increase mid/late Monday morning with a period of strong
winds/gusts expected Monday afternoon. Gusts into the 30-35kt
range expected and could be a bit higher but confidence too low to
include higher gusts at this time. cms
&&
.MARINE...
211 PM CST
Headlines...Upgraded the watches to warnings. Occasional storm force
gusts are possible Monday afternoon and evening over the north half
of the lake. Do not think storm force gusts were frequent enough to
warrant a watch or warning.
High pressure over Ontario and stretching down the Atlantic coast
will continue east. Meanwhile the strong low over the Rockies will
deepen as it shifts over the plains. The low then weakens as it
reaches Ontario Monday afternoon. Southeast winds increase through
this evening. Small craft conditions begin this afternoon and gales
are expected over the open waters this evening. Winds become south
and diminish as a warm front lifts north early Monday morning. The
low`s cold front then slides across the lake, and winds become
southwest behind it. Winds increase across the lake to gales, and
occasional storm force gusts are possible across the northern half.
Winds diminish as the low continues east over Quebec. A high
pressure ridge passes over the lake Tuesday evening. Another
surface low travels over Ontario Wednesday night into Thursday. At
the same time, a high develops over the southern plains. The
increased pressure gradient may lead to gales Thursday afternoon and
night. The pattern remains active with another ridge passing over
the lake Friday evening followed by a low over the weekend.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...Gale Warning...LMZ777-LMZ779 UNTIL 6 AM Monday.
Gale Warning...LMZ777-LMZ779...NOON Monday TO 3 AM Tuesday.
Small Craft Advisory...NEARSHORE WATERS
UNTIL NOON Monday.
Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...NOON
Monday TO 10 PM Monday.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
953 PM CST Sun Dec 25 2016
.UPDATE...
Issued at 953 PM CST Sun Dec 25 2016
Updated to include 06Z aviation discussion below.
&&
.SHORT TERM...(This evening through Monday)
Issued at 342 PM CST Sun Dec 25 2016
Icing threat continues across central MN and portions of west
central WI, especially along Highway 8, for a few more hours with
surface temperatures expected to be a degree or two above 32 degrees
by this evening. The most concentrated precipitation on radar is
over our far northern MN counties with significant icing likely. The
ice storm warning remains in effect until 6 pm. We did extend the
freezing rain advisory to the east of St. Cloud to Rice Lake and
Ladysmith until 6 pm as well.
There are two chances for thunderstorms this evening. The first is
ongoing around Hutchinson on west and these will lift through central
during the balance of the afternoon. A second small line of storms
should push northeast across much of the FA early this evening ahead
of a dry line. This line right now extends from near KFSD through
KOMA.
Another big concern heading through the evening as well as overnight
and Monday is strong winds. Strong pressure falls are spreading into
southern MN right now. RAP data indicates sustained southeast winds
of 30 to 35 mph developing across much of southern MN and parts of
western WI by this evening. BUFKIT profile data from the RAP
suggests wind gusts reaching 50 mph. This type of wind is currently
occurring in IA and will spread north. A lull in the wind will
likely occur late in the evening/overnight hours before strong
pressure rises spread in from the southwest. This will cause west to
southwest winds of 30 to 35 mph to occur along with gusts to 50 mph.
The concern with the wind late in the night and Monday is that we
will have CAA going on with deeper mixing occurring. Top of the
channel winds on the RAP indicate winds of 60 mph possible. Hence,
we issued a wind advisory for southern MN and for St. Croix and
Pierce counties in WI until Monday afternoon. However, the wind
advisory may need to be expanded farther north this evening and
portions of it may also need to be upgraded to a high wind warning
if the 60 mph gusts start showing up to our southwest later in the
evening.
Otherwise, temperatures will slowly rise through much of the night
with some lower to middle 40s around the Twin Cities in the early
morning hours. By daybreak however, temperatures will have taken a
nose dive and be back at or below freezing. Little warming will
occur on Monday. There will also be some snow showers tomorrow as
well, mainly across central MN and west central WI. Accumulations
up to an inch are possible.
.LONG TERM...(Monday night through Sunday)
Issued at 342 PM CST Sun Dec 25 2016
The long term still looks to be fairly quiet across the region.
Zonal or northwesterly upper flow looks to prevail through the
period, keeping decent moisture from working into the region. So,
although we will see a couple of short wave troughs move through,
there are only minimal precipitation chances. There are certainly
some differences in the details of the model guidance, but not
with the big picture, so a consensus approach should provide a
reasonable forecast.
Today`s system will be filling and exiting the region Monday
nigth, with a ridge of high pressure working in from the west. The
next system to impact the area will arrive during the Wednesday
into early Thursday time frame. A short wave trough will drop
east-southeast through the region, pushing a cold front across the
area Wednesday afternoon. The best large scale forcing looks to be
to our north, and deep layer moisture is minimal, so the frontal
passage looks to be mainly dry. There will be some chance for snow
showers in the cold advection and cyclonic flow late Wednesday
night and Thursday, but nothing significant. We`ll then have
another ridge of high pressure bringing fair and dry weather
Thursday night through Friday night before another quickly moving
short wave trough moves through on Saturday. Once again, there is
minimal moisture return ahead of the system, and the better
forcing is to our north, so main chances of any light snow look to
be over the northern portion of the area. Temperatures for the
week look to be a bit above normal as we`re primarily under the
influence of Pacific air masses.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 953 PM CST Sun Dec 25 2016
No significant changes to earlier forecast. Main concerns will be
ceilings, and period with perhaps VFR ceilings overnight, and
strong winds. Gusts may need to be increased for the overnight
period depending on how upstream observations fare in the next
hour or two.
KMSP...Primary uncertainty is if and how long we`ll lose lower
ceilings overnight, and how high of wind gusts we`ll see,
particularly between 06Z and 09Z.
/OUTLOOK FOR KMSP/
Tuesday...VFR. West wind decreasing to 5 to 15 kt and becoming
south.
Tuesday night...VFR. South wind 5 to 10 kt.
Wednesday...VFR. Southwest wind 5 to 15 kt becoming west.
Wednesday night...MVFR possible late. West wind 10 to 15 kt
becoming northwest.
Thursday...MVFR possible early. Northwest wind
15 to 25 kt.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Wind Advisory until 3 PM CST Monday for WIZ023-024.
MN...Wind Advisory until 3 PM CST Monday for MNZ054>057-060>063-069-
070-076>078-083>085-091>093.
Wind Advisory until 3 PM CST Monday for MNZ044-045-049>053.
High Wind Warning until 3 AM CST Monday for MNZ058-059-065>068-
075.
Wind Advisory until 11 PM CST this evening for MNZ058-059-
065>068-075.
Wind Advisory from 3 AM to 3 PM CST Monday for MNZ058-059-
065>068-075.
High Wind Warning until 6 AM CST Monday for MNZ064-073-074-082.
Wind Advisory until 10 PM CST this evening for MNZ064-073-074-
082.
Wind Advisory from 6 AM to 3 PM CST Monday for MNZ064-073-074-
082.
&&
$$
UPDATE...
SHORT TERM...RAH
LONG TERM...
AVIATION...
Area Forecast Discussion
National Weather Service Paducah KY
900 PM CST Sun Dec 25 2016
.UPDATE...
Issued at 900 PM CST Sun Dec 25 2016
The Dense Fog Advisory for parts of sw Indiana and srn Illinois will
likely be allowed to expire at 10 PM. Vsbys have been improving from
south to north as anticipated. Low level winds have increased to
around 40 kt at 925 mb, per regional radar vad wind profiles. This
trend will continue through the early morning hours, which will
scour out the remaining fog areas.
The other concern is convective potential. The convective fine line
over western Missouri this evening is forecast by the 00z nam and
hrrr to weaken late tonight as surface-based instability disappears.
There is some potential for convection to re-intensify on Monday
over our region. Both the 00z nam and rap develop a narrow axis of
surface-based capes by 18z over southeast Missouri and southern IL.
Winds aloft will remain quite strong, at least 40 knots at 925 mb.
Some gradient wind gusts from 30 to 40 mph are likely by midday as
the low level inversion breaks. A few higher gusts are possible in
convective elements.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 249 PM CST Sun Dec 25 2016
Main effects to our sensible weather will come with the coming and
going of a cold front Monday.
A warm front continues to lift north across the region this
afternoon. Stubborn, foggy conditions and chilly temps in the 40s
lie along/north of the front, while in the warm sector south of
the front, esp in wrn KY, southerly winds and off/on sunshine
have kicked temps to record levels in the upper 60s and lower 70s.
The front will continue to lift north tonight, and most areas
should be within the warm sector regime by mid-evening. Temps will
not fall much from our highs, and in fact will likely continue a
slow rise over northern locations tonight. Southerly winds will
increase later tonight ahead of the next cold front pushing east
toward the region. Some locations over se MO/srn IL may see some
gusts up over 30 MPH before dawn, and these conditions will spread
east during the day Monday.
A band of showers/isolated thunderstorms is expected to accompany
the frontal passage from west to east Monday, with highest chcs
wrn locations in the morning and far eastern locations later in
the day. Some model data progging MUCAPES up into the 200-500 J/KG
range and sfc dew points up near 60, so will need to monitor for
any stronger bowing segments within the band of showers. No major
impacts expected at this time tho.
Some indications are that the front may hang up a bit along the
Ohio River tomorrow afternoon, so will need to hang onto fairly
high pops into the evening over the se half of the forecast
region. Otherwise, expect cooler and drier conditions to filter in
on the heels of the front Monday night through Tuesday.
.LONG TERM...(Wednesday through Sunday)
Issued at 249 PM CST Sun Dec 25 2016
Medium confidence through the week...with lower confidence for the
weekend solution.
Starting Wednesday models are in good agreement that a cold front
will rapidly move through. The more consistent ECMWF suggest thunder
will be possible across most if not all of the area. Mostly in SEMO
in the morning then spreading eastward in the afternoon. Then it
rapidly is shunted to the east Wednesday evening. This is well
supported with negative showalters from the ECMWF which is in
contrast to the more stable GFS. In addition K index values will are
expected to reach 30c. However the models due agree on a surface
based inversion...any convection will definitely be elevated with
positive LI`s and little to sb CAPE. The air mass in the fronts wake
originated from the Pacific...so it will not be a major drop in
temperatures. As a matter of fact we are expecting temperatures to
remain above normal through the week. High pressure will assume
control of the pattern until the weekend. Saturday a warm front will
lift through Saturday into Saturday night with cold front following
in its wake Sunday. Showalters go negative in the warm sector
Saturday night in the warm sector over our area. May have to
introduce thunder for that time as well but will wait and see what
collaboration dictates along with higher confidence with successive
model runs. To reiterate temperatures should be above normal through
out the extended. Also the trends of the models has been warming so
will introduction of any wintry mix for early Saturday morning in
SEMO for now.
&&
.AVIATION...
Issued at 503 PM CST Sun Dec 25 2016
While there may be breaks this evening, overall the night-time
will see restricted IFR and MVFR CIGS, with accompanying
restricted VSBYS at least until the warm front makes passage. Then
it`s a waiting game til the cold front increases rain chances
through the day tmrw, with near certain showers/storms effective
by the end of the valid period. Winds will turn to the south and
become gusty in the warm sector.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Dense Fog Advisory until 10 PM CST this evening for ILZ075>078-
080>083.
MO...None.
IN...Dense Fog Advisory until 10 PM CST this evening for INZ081-082-
085-086.
KY...None.
&&
$$
UPDATE...MY
Area Forecast Discussion
National Weather Service Shreveport LA
935 PM CST Sun Dec 25 2016
.UPDATE...
Minor tweaks made to the ongoing forecast, such as a gradual decline
in sfc temps versus a quicker cool-down per the forecast package. In
addition, a vigorous upper level low pressure system translating
northeast across the central and northern Plains, has an associated
Pacific cold front moving east across north central TX and central
OK. Along the front, scattered showers and thunderstorms have
developed and high-res models such as the HRRR hint at this
precipitation activity impinging on the extreme southeast OK and
northeast TX areas at or around midnight. The forecast package
reflects this trend so no need to update pops or wx.
&&
.PREV DISCUSSION... /issued 523 PM CST Sun Dec 25 2016/
AVIATION...
Deep sw flow with plenty of low lvl moisture will mean that low
VFR decks will transition to MVFR and possible IFR where fog and
drizzle set up. South winds gusting to near 20 kts will diminish
to 5 to 10 mph later tonight as flight conditions deteriorate.
Increased showers with marginal conditions for some thunder across
mainly western portions of area after 26/18z. Post frontal
moisture still in place in low lvls for RW. However, drier mid
lvls over mainly ne TX portions of area will lessen thunder
potential as sfc winds becmg sw./VII/.
PREV DISCUSSION... /issued 218 PM CST Sun Dec 25 2016/
DISCUSSION...
Tightening pressure gradient and sfc heating has resulted in a
mixing down of strong low level winds with wind gusts upwards of
30 mph across most of NE TX/SE OK/SW AR and portions of NW LA this
afternoon. As the nocturnal inversion sets up after sunset...
these winds should diminish slightly overnight.
Upper level trough responsible for the increased winds today and
our shower and thunderstorm maker for tonight and Monday is
currently churning its way across the Inter Mountain west this
afternoon and is fcst to quickly eject out into the Central
/Northern Plains tonight. As the trough lifts out into the Plains,
it will be dragging a cold front with it across the Southern
Plains. This front is currently moving through Western Oklahoma
and the TX Hill County and should be approaching our extreme NW
Zones by midnight tonight and near the I-30 corridor of NE TX into
SW AR by 12z Mon. Have increased pops to likely category...mainly
near and to the northwest of this boundary overnight...with a
majority of the convection expected to initiate after midnight.
The front will slow as it approaches Northwest Louisiana Mon aftn
as flow aloft will remain from the southwest. The front will
continue to be a good focusing mechanism for scattered to
numerous showers and marginal 700-500mb lapse near 6.5 deg C/KM
suggest that thunderstorms will be possible during the day Monday
along and ahead of the frontal boundary.
The front should make slow south and east progress Monday Night
into Tue...maybe pushing completely through our region during the
day Tue before beginning to lift back to the north as a warm front
late Tue Night into Wed. Upper flow is virtually west to east
during this time but isentropic lift in advance of the northward
returning boundary will result in at least low chance pops
remaining in the forecast until our flow becomes northwest aloft
during the day Thursday. This flow will help to push a much
stronger cold front through the region on Thu...thus ending our
precipitation chances by late week.
A very progressive upper flow pattern is the best way to describe
the tail end of the extended periods as yet another upper trough
is fcst to move out of the Southwest CONUS and into the
Southern/Central Plains Friday Night into Saturday. This will
result in increasing chances of precipitation once again to close
out 2016.
Prelims to follow...13.
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 66 76 58 65 / 40 70 70 30
MLU 65 78 61 64 / 30 40 60 30
DEQ 59 70 47 62 / 70 40 20 10
TXK 63 71 51 61 / 70 60 60 20
ELD 65 74 54 59 / 40 60 70 30
TYR 64 71 54 64 / 70 60 60 30
GGG 65 73 56 64 / 60 70 70 30
LFK 67 78 62 71 / 30 50 60 30
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
29/07/13
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Monday)
Issued at 330 PM CST Sun Dec 25 2016
Early this afternoon a line of showers and thunderstorms ahead of a
Pacific cold front was pushing east and should reach the western
counties of the CWA after 19Z. The deep upper trough was lifting
north-northeast across southwest NE. The thunderstorm updrafts
within the line may pulse up to around 8,000 to 10,000 feet and
cause some of the stronger momentum parcels at 700mb to reach the
surface in the downdraft of these low top storms. There is still a
chance of some severe wind gusts across the western half of the CWA
during the afternoon hours. However, most of the higher resolution
models show the instability remaining rather low across much of the
CWA. The RAP, HRRR and WRF solutions show SBCAPE only around 250
J/KG. So thunderstorm updrafts may have a difficult time remaining
intense with such stronger vertical windshear. However, I do expect
some isolated damaging wind gusts will be possible through the early
afternoon and mid afternoon hours within the severe thunderstorm
watch box. This afternoon highs will reach the mid to upper 60s
along and south of I-70. Expect lower to mid 60s north of I-70.
Early this evening the line of showers and thunderstorms will move
east into MO. There may be a few post frontal showers and strong
ascent will continue across the CWA. The strong south-southwesterly
winds will slowly diminish through the evening hours.
Monday, will be cooler as westerly winds become northwest. Though
high temperatures will be above normal with highs in the lower to
mid 40s.
.LONG TERM...(Monday night through Sunday)
Issued at 330 PM CST Sun Dec 25 2016
Dry weather and seasonal temperatures are expected for the upcoming
week as the region generally remains under the influence of surface
high pressure. Models continue to show several shortwave troughs
developing through the week, but the mid-level flow keeps these
waves tracking over the northern U.S. As surface high pressure
moves into the region on Monday and tracks into the southeastern
U.S. on Tuesday, the shift to light southwesterly winds will warm
temperatures slightly from Monday with highs near 50 degrees. Weak
warm-air advection will continue into Wednesday with highs rising
into the low/mid 50s. A stronger shortwave trough will track across
the Northern Plains Wednesday into Thursday, and the northwesterly
flow aloft over the region by Thursday will return high temperatures
into the 40s for the remainder of the week.
Models are still showing the next potential for precipitation being
during the New Years holiday weekend, however there are still
significant model differences in the timing of precipitation and the
precipitation type. Models show an embedded shortwave over the
southwestern U.S. lifting northeastward into the area over the
weekend, which could bring some scattered precipitation. However,
the GFS is much faster than the ECMWF with precipitation chances on
Saturday while the ECMWF doesn`t bring precipitation into the area
until early Sunday morning. The ECMWF is also warmer than the GFS,
but low temperatures should still drop to near or below freezing.
As a result, have kept the mention of rain or snow.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 542 PM CST Sun Dec 25 2016
VFR conditions return quickly as line of showers and embedded
stronger winds moves east. Winds diminish and shift westerly
through the forecast.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM CST this evening for KSZ008-009-020>024-
026-034>040-054>056-058-059.
&&
$$
SHORT TERM...Gargan
LONG TERM...Hennecke
AVIATION...67