Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/06/18
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM...(This Evening through Tuesday Afternoon)
Issued at 329 PM CST Mon Feb 5 2018
A pressure surge/cold push along with surface heating has brought
some lower clouds to the area along with some flurries showing up on
radar. Thus, added in isold flurries across the east for the rest of
the afternoon. Otherwise, the Arctic high pressure area to our
northwest will settle over the region tonight with skies clearing
and winds going light. This will bring a very cold overnight with
lows mainly in the single digits below zero with some teens below
zero in the James Valley. The models then show a short wave trough
dropping in from the northwest on Tuesday spreading clouds across
the cwa along with some light snow. Expect areas of light snow to
spread from west to east with only a few tenths of an inch
accumulation possible by evening. Warmer air advecting in on south
winds will bring highs in the teens and 20s by late afternoon.
.LONG TERM...(Tuesday Evening through Monday)
Issued at 329 PM CST Mon Feb 5 2018
First look at Wednesday morning, decided to lower temperatures below
blended guidance. Weak feature is mostly moved east and clouds
should also be clearing west of the James valley after midnight. Low
level flow has a weak gradient but the center of the high is still
up in northwest North Dakota, but migrating towards the CWA. Thus,
given recent snow cover to at least partially mask the radiation of
the earth, readings should crash with loss of cloud cover and an
already cold start.
The long range pattern will be dominated by the upper trough across
eastern North America with generally northwest flow aloft through
about the end of the work week, though guidance diverges after that
and confidence drops on conditions for next weekend. That said, there
will be plenty of weather as guidance parks a deep layer of stratus
across the forecast area, mainly from northwest to southeast South
Dakota, impacting the western and central CWA. Not really much of a
wave aloft, but off and on weak isentropic ascent or warm advection
aloft could be the impetus for light snow generation despite lift
generally less than 10 microbars. Low level pattern features
sprawling high pressure to the north and an increasing tightening
pressure gradient to the southwest, but low level flow over our CWA
during this time is also weak and winds will likely not be an issue.
As for temperatures, we remain mainly on the cold side of the Arctic
front, with an increasing thermal gradient from southwest to
northeast Thursday/Friday and a wobble southwards. Thus,
temperatures will continue below average through the end of the work
week and likely into the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 625 PM CST Mon Feb 5 2018
Stratus/strato-cu has dissipated and all four terminals should be
good VFR through at least 12Z Tuesday. Throughout the day on
Tuesday, low/mid-level (VFR-MVFR) cloudiness will spread/develop
east over the forecast area and increase in coverage. RAP model
soundings in BUFKIT do show full saturation occurring within the
dendritic growth zone in tandem with enough synoptic scale lift to
produce some (MVFR-IFR) light snow on Tuesday, earlier in the day
for KMBG/KPIR and later in the day for KABR/KATY.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...Mohr
LONG TERM...Connelly
AVIATION...Dorn
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
915 PM CST Mon Feb 5 2018
.DISCUSSION...It appears that the coastal trough over the coastal
waters has weakened and wind flow along the coast has shifted to
more of an easterly direction. Dewpoint temperatures in the upper
60s over the offshore waters will continue to move toward the
coast as the coastal trough axis approaches the coastline.
Although there are no observations in the near shore waters,
suspect there is dense fog in the region similar to the what is
observed off the coast of Matagorda Bay. Visibilities have lowered
along the coast and expect this will continue through the night.
See Marine section for Dense Fog Advisory.
Looking at latest RAP model along 00Z NAM, it looks like the trough
axis will continue to move inland during the day on Tuesday. This
will lead to slightly warmer temperatures over inland coastal plains
and raised max temps about a category. Also, removed mention of
drizzle and fog in the afternoon. Northern Brush Country could see
fog linger into the early afternoon.
&&
.MARINE...With coastal trough approaching the coast during the
overnight hours, warm moist air will continue to move across the
cooler shelf waters. Dense fog over the near shore waters should
move into the bays later this evening and continue through the
morning hours. Will issue Dense Fog Advisory for bays and near
shore waters until 18Z Tuesday.
&&
.PREVIOUS DISCUSSION... /Issued 547 PM CST Mon Feb 5 2018/
DISCUSSION...See Aviation section for 00Z TAFs.
AVIATION...MVFR ceilings will continue to prevail across the
region early this evening except along the immediate coast. The
higher resolution models depict the coastal trough, over the
offshore waters of the middle Texas coast, will be slow to move
inland during the afternoon hours on Tuesday. Expect ceilings
will fall to IFR by mid evening over the coastal plains and after
midnight over the Brush Country. Aviation conditions will further
deteriorate around 06Z over the coastal plains to LIFR in fog
and light drizzle. LIFR ceilings expected to reach LRD area around
daybreak. Vsbys are expected to improve from 15-16Z but IFR
ceilings will linger into the afternoon. As the coastal trough
moves inland during the afternoon, vsbys will improve but expect
IFR ceilings will remain over the coastal plains with MVFR
ceilings over the Brush Country.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 59 72 53 57 45 / 20 20 40 70 40
Victoria 56 70 45 49 41 / 20 30 50 60 20
Laredo 59 71 52 56 43 / 20 30 30 50 30
Alice 58 74 52 56 42 / 20 30 40 70 40
Rockport 58 66 51 55 45 / 20 20 40 70 40
Cotulla 56 64 48 52 41 / 20 30 30 60 10
Kingsville 60 76 57 61 43 / 20 20 30 70 40
Navy Corpus 59 68 55 59 46 / 20 20 30 70 40
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Dense Fog Advisory until noon CST Tuesday For the following
zones: Bays and Waterways from Baffin Bay to Port Aransas...
Bays and Waterways from Port Aransas to Port O`Connor...
Coastal waters from Baffin Bay to Port Aransas out 20 NM...
Coastal waters from Port Aransas to Matagorda Ship Channel
out 20 NM.
&&
$$
TMT/89...SHORT TERM
Area Forecast Discussion
National Weather Service Cheyenne WY
630 PM MST Mon Feb 5 2018
.UPDATE...
Issued at 625 PM MST Mon Feb 5 2018
Allowed all winter headlines to expire on time at 5PM and 6PM.
Looks like all the colder cloud tops now are down in Colorado, so
most of the energy for producing snow now further south. Will keep
an eye on current snow band. This band extends from Harrisburg to
Chugwater to Wheatland this evening. But it is moving, so heavy
snow accumulations are not likely I think. Updates sent.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 225 PM MST Mon Feb 5 2018
Tonight...Expecting instability type banded snow showers to continue
into the evening hours, most numerous along the southern portion of
I-25 where the baroclinic band resides along the cold front. Snow
showers expected to decrease in coverage after midnight as the best
lift moves into Colorado.
Tuesday...Much less coverage of snow showers as low and mid level
moisture decreases with less lift. However, expect orographic snow
showers to continue over our Snowy and Sierra Madre Ranges with some
moisture over there. 700 mb temperatures near -10 Celsius will yield
high temperatures mainly in the 30s.
Tuesday night...Orographic snow showers will decrease in coverage
across our Snowy and Sierra Madre Ranges as moisture wanes. Should
still see plenty of middle and high clouds streaming overhead,
however, based on model projections.
Wednesday...Moderate warming trend expected as heights and thicknesses
rise. Breezy to windy west of I-25 based on low and mid level gradients.
.LONG TERM...(Thursday through Monday)
Issued at 225 PM MST Mon Feb 5 2018
Northwest flow aloft Thursday will back to the southwest as shortwave
energy carves a positively-tilted upper trough over CA/NV by Saturday.
A closed upper low forms over southern CA by Sunday morning, ejecting
east-northeast across northern AZ/NM Monday.
Thursday will be mild and dry with breezy to locally windy conditions
along and west of the Laramie Range. High temperatures will be in the
40s to lower 50s. The CAG-CPR 700/850mb gradients increase to 55-60
meters Thursday night and early Friday ahead an approaching cold front
from the north. 700mb wind rise to 50-55 kt between Laramie and Rawlins
by Friday morning. High Wind headlines may be needed at that time. Light
snow gradually spreads north to south late Thursday night through Friday.
The cold front will push southwest to near the CO border Friday night
and early Saturday morning. Widespread snow will continue through Saturday
afternoon, tapering Saturday evening. High temperatures Saturday will
range from the upper teens north to upper 20s south. The GFS shows a
wide swath of high QPF (near a 1/2 inch) along and south of a Rawlins
to Sidney line, while the ECMWF is lighter on its amounts. Should the
GFS scenario pan out, we could be dealing with several inches of snow.
Still have time to iron out the details with the model differences,
but certainly something that bears watching the next couple of days.
The front lifts northeast as a warm front Sunday with drier conditions
and slowly moderating temperatures into early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 625 PM MST Mon Feb 5 2018
IFR conditions in snow for areas along and south of a line from
Sidney to Wheatlnd to include KCYS. Latest HRRR guidance holds IFR
conditions here at KCYS through early tomorrow morning (10Z). Will
continue to monitor.
&&
.FIRE WEATHER...
Issued at 225 PM MST Mon Feb 5 2018
No concerns with chilly temperatures and minimum humidities above
critical thresholds. Most areas will receive accumulating snow this
afternoon and tonight and again Friday through Saturday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...GCC
SHORT TERM...RUBIN
LONG TERM...MAJ
AVIATION...GCC
FIRE WEATHER...RUBIN
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
936 PM CST Mon Feb 5 2018
.Update...
Issued at 935 PM CST MON FEB 5 2018
With the wintry precipitation moving out of the forecast area, the
Winter Weather Advisory has been allowed to expire. Our focus now
turns to the next system, which is currently developing out near
the Four Corners. Models continue to indicate the best chances for
snow are across northern MO and northern KS, including the north-
side of the KC Metro area. Most likely snow totals are 1-3 inches,
but uncertainty with storm track and snow amounts still exists.
Additionally, the KEAX WSR-88D will remain down during this
winter event. Surrounding radars (MCI, KTWX, KOAX, KDMX, KLSX,
KSGF, and KDVN) will be available though. For more information,
please visit www.weather.gov/eax/radaroutage.
&&
.Discussion...
Issued at 229 PM CST MON FEB 5 2018
Weak wave currently moving through the area with sporadic reports
if -FZDZ received across the area. Quick look at both NAM and RAP
fcst soundings should suggest enough saturation in the snow
growth region to result in all snow, however have added a patchy
FZDZ mention in for this afternoon`s fcst. Otherwise, this feature
should have little impact on the area with maybe a few tenths of
an inch of new snow possible across our northern most fcst zones.
This system should exit stage right by 03z, setting the stage for
what should be another chilly night thanks to yesterday`s
snowfall and a short duration clearing trend. Couple those factors
with the fact that we`re sitting at 20 degrees at the office this
afternoon, overnight lows in the low to mid single digits again
seem plausible.
This leads us into tomorrow`s well-advertised storm system. What a
difference from last week`s model presentation, which originally
showed a leeside low lifting north from the southern High Plains,
with a cold front and associated frontogenesis max approaching
from north, which were to both act as additional forcing
mechanisms for precip production. Now, models show no hint of a
leeside low, with all forcing for this feature resulting from
midlevel frontogenesis and weak synoptic scale forcing from a
passing open wave. Considering temperatures will be more than cold
enough to support all snow, the main factor influencing today`s
fcst involves a northward shift of the heaviest precip axis, which
now appears will occur north of the KC metro. In fact, a pretty
tight snowfall gradient may occur across the metro, with the
northland possibly seeing 1-3" totals, while areas south of the
Missouri River struggle to reach an inch. If one were to believe
the NAM, little if any snowfall will occur south of the Missouri
Rvr. Even the GFS has trended north this afternoon, however it
still remains the most bullish on snow totals for the metro.
Considering this trend, along with the fact that forcing as a
whole just doesn`t appear all that strong, have taken the liberty
of refining snow totals this afternoon, mainly based on these
latest trends. It still stands to reason that a swath of 2-4"
could occur north of the metro, maybe from the St. Joe area
northeast through Kirksville, however, amounts south of the river
look to be lower than previously thought. The other factor that`s
worth noting is the fact that this feature will likely arrive
later than previous fcsts had suggested, with snow moving into the
KC metro after 18z, with all activity pretty much off to our east
by 06z at the latest. Considering the timing differences, the AM
commute should get along just fine, with conditions possibly
worsening through the evening commute. That said however, heaviest
snows may hold off long enough to prevent too many problems for
tomorrow`s evening rush, so lets keep our fingers crossed.
Beyond Tuesday`s system, broad northwest flow looks to dominate
through the end of the week with the next chance for precip
looking to arrive on Friday when another cold front approaches
from the north. Precip will likely grow upscale Friday ngt into
Saturday as additional energy lifts northeast from the Southern
Plains, with current thermal profiles suggesting enough warm air
in place to result in mostly rainfall. System to then pass though
Saturday night, with cold air settling south and possibly
transitioning precip back to snow on Sunday.
&&
.Aviation...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 548 PM CST MON FEB 5 2018
Light snow, with patches of freezing drizzle have been moving
through the area, with the bulk of the snow falling north of HWY
36. This activity will continue to move east, exiting the area
around 03Z. Conditions should improve in the next few hours or so
behind this system, leaving everyone dry, with mostly clear skies
tonight through about dawn. This is when the next system will
approach. Light to moderate snow is likely with this system
starting in the afternoon and right now, model consensus shows the
bulk of the snow will be north of I-70. Low ceilings and visibility
will accompany the snow, likely causing MVFR conditions and
potentially IFR visibilities. There is uncertainty though where
the snow/ no snow line will be, with IXD near that line right now.
So for the time being, have kept the snow mention to VCSH there
with VFR conditions. Timing and location of snow could still
change though, so should have at least a little better of a
handle for the next TAF issuance.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Update...Grana
Discussion...32
Aviation...Grana
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
515 PM MST Mon Feb 5 2018
.SHORT TERM...(Tonight through Tuesday night)
Issued at 248 PM MST Mon Feb 5 2018
Scattered snow showers have picked up with daytime heating today
across northwestern Colorado in narrow bands of convection just
ahead of an approaching trough. The trough advecting colder air
into the region will pass northwest to southeast through eastern
UT and western Colorado tonight and into Tuesday morning. This
system has slowed down about 12 hours from the previous forecast
solutions from 24 hours ago. Showers will be possible along this
front, so many locations may see rain, snow or a mix of both
overnight through Tuesday afternoon. A few lightning pulses have
been detected near Juniper Springs today, and this threat will
continue through the nighttime hours.
As the trough passes through late tonight, a band of
precipitation is expected to develop south of I-70 and as far
south as the northern San Juans. The HRRR and RAP indicate a
secondary band of precip developing toward the early morning hours
across the San Juans, which will also bring a chance of precip to
the Four Corners valleys for a short window Tuesday morning. Snow
amounts are generally expected to be light, with the exception of
the advised areas of the central CO mountains and very high
elevation spots in the northern San Juans. With this trough`s
convective nature, brief whiteout conditions will be possible
through Tuesday morning where heavier showers pass through.
The atmosphere stabilizes Tuesday evening leaving cooler
northwesterly flow in place.
.LONG TERM...(Wednesday through Monday)
Issued at 248 PM MST Mon Feb 5 2018
Stable conditions continue in northwest flow Wednesday and
Thursday with daytime temperatures gradually increasing toward the
end of the week as warm air slowly advects into the region at
mid levels. A huge divergence in model solutions remains for the
weekend - with the GFS much more interesting and dynamic with a
split off closed low over the Desert Southwest, the EC keeping
the region in NW flow, and the CMC in the middle. The ensemble
products as a whole swing a trough through eastern UT and western
CO over the weekend, so odds are that somewhere in eastern UT and
western CO will see some clouds and precipitation over the
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 515 PM MST Mon Feb 5 2018
The northern and central Colorado mountains will continue to
remain obscured in snow showers this evening through Tuesday
morning. ILS breakpoints will be reached at KHDN, KEGE, KASE, AND
KTEX through 18Z Tuesday with the greatest impact between 09Z and
15Z due to showers and low ceilings/visibility. Elsewhere,
scattered showers will bring light precip from time to time
through Tuesday morning with BKN to OVC skies and some low
ceilings here and there. Conditions expected to improve by midday
Tuesday as drier air moves back into the region.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 9 AM MST Tuesday for COZ010-012.
Winter Weather Advisory until 5 AM MST Tuesday for COZ004-013.
UT...None.
&&
$$
SHORT TERM...JAM
LONG TERM...JAM
AVIATION...MDA
Area Forecast Discussion
National Weather Service Grand Rapids MI
923 PM EST Mon Feb 5 2018
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 330 PM EST Mon Feb 5 2018
A quick burst of snow will move across Southern Lower Michigan
tonight and this will be enhanced by Lake Michigan. All told, areas
along the lake shore and along I-94 west of Battle Creek should see
4 to 6 inches. Meanwhile areas NE of Grand Rapids will see 2-4
inches, while areas toward Mt. Pleasant will only see 1-2 inches.
Another round of snow will arrive Tuesday night into Wednesday.
Even more snow is expected Thursday night and again Saturday and
Saturday night. It will remain cold into early next week with daily
highs in the 20s to lower 30s.
&&
.UPDATE...
Issued at 924 PM EST Mon Feb 5 2018
It would seem the snow bands we expected to develop have in fact
developed but they have not become organized into one coherent
snow band. The latest RAP model shows the best lift and
convergence just west of Grand Rapids but over time, as the
surface trough comes through around midnight, that wills shift
that area south and east. There seems to be some directional wind
shear in the clouds with the snow bands too and that is not
helping the cause for heavier snowfall. As a result I have
decreased the expected snowfall into the 1 to 3 inch range. I will
leave all headlines as is even so.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 330 PM EST Mon Feb 5 2018
Will make a couple more tweaks to the current headlines as accums
continue to trend a bit higher. Will add Ingham and Jackson
Counties to the advisory. Also will end the advisory at 10Z as this
is a quick hitter and the snow should be over prior to the morning
commute.
Coupled upper jet will be squarely over the region later this
evening, bringing the steady snow that was over IA and Northern IL
into Southern Lower. Snow accums in IA have been in the 4-5 inch
range, and since this will be lake enhanced expect at least that
amount to occur here.
The lift from the upper jet will be strongest over the area south of
I-96, so it makes since to include Ingham and Jackson. Areas west
of U.S. 131 will also see decent snows largely due to the lake
effect. Mean flow early this evening will be about 250, but by late
evening it will pivot to 280-290. So this sprays the entire lake
shore as the moisture depth is healthy. Highest totals of 4-6
inches are expected south and west of Hart to Freemont to Battle
Creek. The advisory buffers this line to the north and east, for a 2-
4 inch accums. The upper jet lifts away quickly, so have the
advisory only running until 10Z. The message will be the snow will
be over by the morning commute, but untreated roads will still be
slick.
Weak lake effect is expected behind the system for Tuesday into
Tuesday evening. This will remain weak due to high pressure moving
in through this period.
Another period of snow is expected for Tuesday night into Wednesday
that will also be lake enhanced and as a surface low tracks to our
SE. Another 1 to 4 inches is expected from this event.
.LONG TERM...(Thursday through Monday)
Issued at 330 PM EST Mon Feb 5 2018
Several waves of low pressure will bring some impacts to the region
during the long term period. Overall confidence is somewhat
diminished based on the lack of model run to run continuity.
One low amplitude wave is shown to arrive Thursday into Friday. The
forcing is forecasted to be relatively weak with this system but it
will be a prolonged period of snow. A couple of inches of snow are
possible. Right now it looks like mostly minor/moderate impacts
from this system. Will maintain high POPs for this event.
Another area of low pressure is shown to track up the Ohio Valley
for Saturday into Sunday. This system will have some better forcing
and will likely tap Gulf Moisture. Thus an increased risk for
moderate or better impacts exists. The forecast soundings from the
latest GFS suggest a mix is possible for far southern lower
Michigan. The High Res Euro is colder with this system. With the
low tracking up the Ohio Valley...will keep the precipitation type
as snow at this point. Will need to monitor trends closely.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 644 PM EST Mon Feb 5 2018
IFR conditions in snow is expected at all of the GRR TAF sites
between 01z and 06z, with AZO and GRR likely to have the lowest
conditions due to a lake enhanced snow band over those two sites.
That should move out in the 06z to 09z time frame but light system
snow may continue till 12z or so. Some lake effect snow is
possible at MKG, GRR and AZO till around 18z . From 12z to 18z I
may not have the visibility low enough for the heaviest snow
showers but the forecast should be good for the prevailing
conditions. Ceilings should mostly be MVFR during the daylight
hours of Tuesday.
&&
.HYDROLOGY...
Issued at 1243 PM EST Mon Feb 5 2018
Quite a bit of fluctuation was showing up in gauge reports from
Portland and Eagle this morning with downstream sites showing
falls. This suggested an ice jam may have formed somewhere
between Ionia and Portland on the Grand River.
Coordination with Ionia County and Clinton County Emergency
Management revealed that Portland`s erratic readings are a bit
higher than actual levels. A lot of ice is jammed up around
Portland, where river levels are near bankfull upstream of the
gauge.
Eagle on the other hand, was spot on with observed levels that
spiked overnight into the early morning as a result of the jam
near Portland. Standing water was reported in low lying farmland
adjacent to the Looking Glass River, but was having minimal
impact. Recent observations show the river has peaked for the time
being and is beginning to recede again. Ice seem to have
stabilized as water flows beneath it.
Forecasts have not changed in regard to the cold air and multiple
rounds of snowfall through the week. Snowfall will not have an
immediate impact. However, it will delay that impact to when
temperatures warm again and ice is less stable. For now, the most
important issue is the continued affects of ice in the event
additional ice jams form.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 5 AM EST Tuesday for MIZ037-038-
043-044-050-056>058-064>067-071>074.
LM...None.
&&
$$
UPDATE...WDM
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...MJS
AVIATION...WDM
HYDROLOGY...JAM
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1058 PM EST Mon Feb 5 2018
.UPDATE...
Issued at 1058 PM EST MON FEB 5 2018
With lack of clouds, temperatures continue to drop off across
eastern Kentucky. Made another adjustment to the current and low
temperatures based off of latest observations, dropping the
overnight lows by another 1 to 2 degrees. Still expecting them to
level off at some point in the next few hours and start slowly
increasing as clouds and precip move nearer to the CWA. Also made
sure the dew points and winds were on track with the current
conditions. All updates have been published and sent to NDFD/web.
A new forecast package was also sent out to reflect the changes in
overnight lows and remove evening wording.
UPDATE Issued at 914 PM EST MON FEB 5 2018
Quiet evening thus far with mostly clear skies and light winds.
Thicker high clouds are just starting to make their way into the
northern CWA, with forecast track for precip related to incoming
system unchanged thus far. After loading in the latest
observations for hourly temps, it was clear that many locations
are dropping off as they are not yet being insulated/moderated by
the cloud cover. some locations current temps were at or just
below the forecasted lows. As such, went in and lowered overnight
lows by a few degrees in most locations, then adjusted the diurnal
curve so that overnight lows were reached in the next few hours,
then moderated and rose slightly through the rest of the night
with the incoming clouds and precip, in addition to more southerly
flow. Will continue to monitor temp trends and update again as
necessary. All changes have been sent to NDFD/web. A new forecast
package will be sent out in the next hour to remove evening
wording and reflect the slight chance in low temperatures.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 340 PM EST MON FEB 5 2018
20z sfc analysis shows weakening high pressure over Kentucky and
this has finally cleared out nearly all the lower clouds. Sunshine
filtered through the present high clouds is helping to raise
temperatures into the lower 30s for the southern half of the CWA
and upper 20s further north. Do not expect the highs this
afternoon and limited sunshine to raise the road temperatures
above freezing going into the night, though. Meanwhile, dewpoints
are in the mid to upper teens with light and variable winds.
The models are in good agreement aloft with this unsettled pattern
of yet another weak shortwave passing quickly through the Ohio
Valley followed by a larger trough approaching for mid week. The
weaker feature passes through tonight skirting along the Ohio
River, while a larger trough moves into the region Tuesday night.
Large scale southwest flow develops along with that latter wave
as the pattern tilts. Given the model symmetry have followed a
blended solution with a strong lean on the higher resolution HRRR
and NAM12 for weather details.
The latest bout of light winter pcpn arrives tonight in the form
of a wintry mix as a weak front moves through. The pcpn arrives
after midnight and passes through from northwest to southeast
before clearing out temporarily by mid morning Tuesday. Although
just a couple of hundredths of an inch of pcpn are possible from
this it does look like ice crystals will be lacking aloft
resulting in freezing drizzle as the main p-type. Some seeding of
ice crystals from higher clouds appears likely at the onset for
light snow and flurries, but that is gone 4 or 5 am. Road
conditions have been an issue that past two mornings and look to
again be a concern for Tuesday morning. The threat for freezing
drizzle or a mixed bag of light pcpn continues through mid morning
Tuesday before the area dries out from west to east. Will issue
an SPS to highlight this light wintry mix concern for late tonight
into Tuesday morning.
Attention will then turn to a more substantial weather maker
moving in from the southwest later in the day and continuing into
the night. This will be well supplied with deep layer moisture
from the Gulf of Mexico. As the sfc low associated with this
moves into the Tennessee Valley Tuesday night it will push warmer
air into eastern Kentucky along with plenty of rain. However, the
northern fringe of this will have a hard time shoving the cold
air out of the way and as a result some mixed pcpn in the form of
sleet and freezing rain look to be on tap - mainly for locations
north of interstate 64 - for a time. By 12z Wednesday, warm air
should have overtaken the entire area switching all the pcpn to
rain - possibly heavy at times.
Used the CONSShort and ShortBlend to initialize the grids with
only minor terrain based temperature adjustments tonight and
Tuesday night owing to a CAA pattern tonight and increasing
moisture Tuesday night. As for PoPs, hit them a bit harder later
tonight than they came in from the blend and also moved them in
quicker from the southwest on Tuesday afternoon.
.LONG TERM...(Wednesday through Monday)
Issued at 346 PM EST MON FEB 5 2018
By Wednesday morning, much of the area should see a nice warm nose
aloft over them. This will keep precipitation all rain through
much of the day. A marginal chance for freezing rain may hold on
in northern Fleming county through the morning, but even there
temperatures should climb enough by the afternoon, to keep things
mainly rain. The main push of rain will come through the morning
hours, with rain tapering off into the afternoon as we lose the
ice in the clouds. We could see a transition to some drizzle into
the evening hours. As temperatures start to cool back below
freezing Wednesday evening, the threat for freezing drizzle will
return and likely last through the night. Eventually, as the lower
levels continue to cool, we may reintroduce ice and may trend
towards more flurries after midnight. Either way, potential exists
for some slick conditions into Thursday morning.
High pressure will then slide east across the region Thursday into
Friday, providing a more tranquil, but cool period of weather.
Heights will start to build quickly into Friday night and Saturday
as a cold front approaches from the northwest. The heights should
recover fast enough, that by the time any precipitation reaches us
Saturday morning, it should all be in the form of rain. Still some
timing differences with respect to when precipitation arrives, but
it does look like a period of wet weather will be seen sometime
Saturday or Saturday night. GFS keeps the threat of rain going
into early the following week, while the ECMWF continues to
maintain the cold front pushing on through and conditions drying
off as we turn cooler again. Clearly still lots of uncertainty
with the late weekend and early next week period, so will stay
close to the blended guidance.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 701 PM EST MON FEB 5 2018
Mostly clear skies and light and variable winds are currently in
place across eastern Kentucky this evening. Another disturbance is
expected to push through late tonight, generally between 8 and 15Z.
This will result in an increase and lowering of CIGS, with MVFR
conditions possible by 9Z. It will also bring in a touch of light
pcpn in the form of light snow or freezing drizzle. For now,
accumulations look spotty at best so will keep it as VCSH in the
TAFs. However, for locations that do see freezing drizzle/rain,
expect slick conditions to develop on tarmacs and last into the
morning before temps rise above freezing. Precip will end and temps
will warm above freezing by mid morning. However, lingering
clouds could hover near MVFR through much of the afternoon. Winds
will generally remain light and variable through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JMW
SHORT TERM...GREIF
LONG TERM...KAS
AVIATION...JMW
Area Forecast Discussion
National Weather Service San Angelo TX
910 PM CST Mon Feb 5 2018
.UPDATE...
Quick update on the forecast for late tonight, Tuesday, and
Tuesday Night. Latest HRRR and NAM both had a bigger push on the
cold air that before, with temperatures dropping during the
afternoon. The 18Z GFS trended that direction as well. With that
in mind, brought the cold air in a little faster on Tuesday. Highs
on Tuesday will likely come a little earlier in the day which will
have some effect on forecast highs, but will have a bigger effect
on forecast hourly temperatures behind the front. Portions of the
Big Country may not be much above freezing for a big part of the
afternoon.
This faster push also has an affect on the chances of freezing
precipitation across the Big Country, including Abilene and
Sweetwater. Brought the mention of light freezing rain and
freezing drizzle into the evening hours (instead of just after
midnight) and am a little concerned that may not be fast enough.
Don`t want to lock the midnight shift into something this early
though, and will allow them some wiggle room. All indications
remain that any potential freezing precip will be light and still
do not anticipate much impact. This will need to be monitored
however.
&&
.PREV DISCUSSION... /issued 529 PM CST Mon Feb 5 2018/
AVIATION...
/00Z TAFS/
Widespread fog and low clouds will affect all terminals throughout
much of the day tomorrow. Fog will develop across KJCT and KSOA
between 08-12z. Prior to the onset of fog, low stratus will bring
MVFR conditions to the terminals. Once the fog develops, IFR
conditions can be expected with visibilities dropping below
1/2SM. The low clouds and fog will spread north and reach KSJT by
09z. Fog will develop across the KSJT terminal bringing IFR
conditions with 1/2SM visibilities and low ceilings. The fog will
slowly begin to dissipate across the terminals between 16-18z,
but low clouds will persist and MVFR with periods of IFR ceilings
will continue across these terminals.
At KABI, fog is not anticipated at this time and the mention of
fog as been left out of this TAF package. The low clouds will
bring MVFR/IFR ceilings with light drizzle to the terminal
beginning at 10z and lasting throughout the rest of the day.
PREV DISCUSSION... /issued 305 PM CST Mon Feb 5 2018/
SHORT TERM...
(Tonight and Tuesday)
.Colder and rainy Tuesday...
Stratus continued to dissipated from west to east this afternoon,
with a nice jump in temperatures into the 60s in the Concho Valley.
Temperatures were still cool in the 40s in the Big Country.
A cold front was moving into the northern Texas Panhandle this
afternoon. Temperatures were not cold with 60s just behind the
front. However there was much colder air in the 20s and 30s northern
Kansas.
The cold front will be moving into the Big Country Tuesday morning,
and midday in the Concho Valley, and afternoon along I-10.
Went cooler with highs in the upper 30s to lower 40s in the Big
Country tomorrow. Temperatures should stay steady or fall slowly
after frontal passage.
Added patchy drizzle in the Concho Valley and areas east and south
tonight after midnight as a warm front temporarily moves north.
There is a 20 to 40 percent chance of rain Tuesday as the cold front
pushes the moist air associated with the warm front, back south.
Rainfall amounts will be light, generally a few hundredths of an
inch.
LONG TERM...
(Wednesday through Tuesday)
Main concerns for this forecast period will be the chances for a
a wintry mix along and north of Interstate 20 Wednesday morning.
Temperatures in the upper 20s combined with a slight chance of
precipitation may lead to some areas seeing some light freezing
rain during the morning. Otherwise, much colder temperatures are
expected for Wednesday afternoon before warming back into the 60s
for Thursday and Friday. The next cold front may pass through
sometime around Sunday dropping temperatures back into the upper
40s to mid 50s. The next chance for rain will be on Monday with
the best chances appearing to be south of Interstate 20.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 34 38 29 47 / 10 30 30 5
San Angelo 42 48 34 49 / 10 20 20 10
Junction 45 58 36 46 / 10 30 30 30
Brownwood 41 45 33 47 / 20 40 40 10
Sweetwater 32 37 28 47 / 10 20 20 5
Ozona 45 58 37 51 / 10 20 20 20
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
07