Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/20/18
Area Forecast Discussion
National Weather Service Binghamton NY
1003 PM EST Mon Feb 19 2018
.SYNOPSIS...
A frontal system will push rain showers into NY and PA over the
next few days. Much milder air will move into our region,
setting the stage for near record warmth on Tuesday and
Wednesday.
&&
.NEAR TERM /THROUGH TUESDAY/...
1000 PM UPDATE...meso scale models are struggling with the slow
movement northward of the rain. So far the HRRR seems to be
doing the best job and have followed it`s timing to lift the
rain out. Otherwise, minor adjustments to the evening temps as
we continue to slowly rise, with the warmest air over the
Finger lakes, and the coldest over the Catskills. Previous
discussion below.
335 PM update...
Issued Flood Watch for Northern Oneida County.
245 PM update...
An unusually warm and humid flow will strengthen Monday night
into Tuesday upstream of a frontal system draped across the
Great Lakes.
Rain showers will run out ahead of the front through this
evening, then taper off over all but the northern forecast area
by Tuesday morning. 925mb temperatures will soar to +11C to +12C
by afternoon, allowing surface temperatures to climb into the
60s.
Little to no QPF is forecast for Tuesday morning through the
afternoon hours.
952 AM update...
Mid and high clouds will continue to stream over NY and PA as
warm air advection increases. The end result will be
temperatures climbing through the 40s through sunset.
The strongest warm air advection takes place late tonight,
setting the stage for rising temperatures through Tuesday
morning, amid decreasing rain shower activity.
Minor changes were made to temperatures with this morning`s
update and were largely based on latest ConsShort.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
245 PM update...
A frontal system parked over the Great Lakes will remain to our
west through midday Wednesday before making a run at our
forecast area late in the day.
Ahead of the front, very mild air be in place. Despite a fair
amount of cloud cover, temperatures will once again push into
the 60s.
Showers along and ahead of the front will arrive over the far
northwestern forecast area during the morning hours, then spread
to the I-81 corridor Wednesday afternoon.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
3 PM update...
The pattern will remain active late this week and into the weekend with
periods of rain and mild temperatures.
The synoptic pattern will remain relatively stagnant during this
time with a broad, amplified upper level ridge over the srn
Atlantic coast...extending nwd into the Northeast and a
continuous supply of moisture being fed n/newd from the srn
Mississippi Valley through the Ohio Valley into the mid Atlantic
region.
A cold front will move through Wednesday night nw to se and allow for a
brief period of cooler and drier weather into Thursday morning.
Temperatures will fall into the 30s. The cold air mass will shift back
to the north/ne Thursday afternoon as a weak upper wave slide ewd
across PA and clips ne PA with a couple tenths of an inch of rain.
Temperatures on Thursday will only warm into the mid/upper 30s NY and
into the lower 40s PA.
Another brief respite from the wet conditions will be felt Thursday
night before the next surface low moves newd through the region Friday
and Friday night along the same stream of moisture from the sw. There
may be a few snowflakes mixed in at times during the overnight/early
morning hours, but generally temperatures should remain warm enough for
all rain. Could see another quarter to half inch. Another lull in the
pattern possible early Saturday before the next system sweeps through
Saturday night/Sunday. May see the rain change to/mix with snow later
in the day Sunday.
Temperatures this weekend will remain on the warm side of climatology
with highs in the mid to upper 40s close to 50...and overnight lows in
the 30s.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
A warm front is lifting northward tonight bringing rain to many
of the sites. As the night wears on, much of the rain will loft
north of the region, however MVFR and spotty IFR conditions
will continue as fog settles into the area. LLWS will affect
mainly of the sites with the light winds near the surface and a
strong low level jet aloft. Conditions improve after 12Z Tuesday
as drier air arrives from the southwest.
Outlook...
Tuesday afternoon through Wednesday morning...VFR.
Wednesday afternoon through Thursday...Chance of restrictions
and rain showers. Rain may mix with snow late Wednesday night-
Thursday morning for the NY terminals.
Thursday night through Friday...Mainly VFR with chance of rain
showers, possibly mixed with snow. Local restrictions possible.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...Flood Watch through late Wednesday night for NYZ009.
&&
$$
SYNOPSIS...DGM/DJP
NEAR TERM...DGM/DJP
SHORT TERM...DJP
LONG TERM...BJT
AVIATION...DGM/DJP
Area Forecast Discussion
National Weather Service Dodge City KS
920 PM CST Mon Feb 19 2018
.UPDATE...
Issued at 919 PM CST Mon Feb 19 2018
Lowered low temperatures substantially Tuesday morning, well down
into the teens, given expected cold air advection and arctic air
upstream. Also added thunder to cover thunderstorm impacting
Barber county.
UPDATE Issued at 815 PM CST Mon Feb 19 2018
Updated to expand the mention of freezing drizzle across roughly
the eastern 1/2 of the CWA for the rest of tonight. 00z NAM shows
a strong drizzle QPF signature roughly along and east of US 283
tonight, with QPF of 0.01-0.04. Setup looks favorable for freezing
precipitation, as cold/dry advection at 850 mb is overrun by
warmer air aloft at 700 mb. Any freezing drizzle will be light,
but it takes very little to impact travel severely, so will need
to watch trends and observations closely tonight. Also, HRRR
continues to suggest convection possible across/near Pratt/Barber
counties after 3 am along surging cold front. NAM also shows some
MLCAPE in this region after midnight, along with surface
temperatures below freezing, so will need to monitor this region
for icing as well.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 158 PM CST Mon Feb 19 2018
Late day convection attempting to develop along a surface cold
front in the Texas panhandle at 1 pm. Once these developing
clouds/showers move north of this boundary however they begin to
weakening as they move into a cooler and more stable air mass. At
this time do not think any convection that does develop late today
in the Texas Panhandle will make it to the Oklahoma/Kansas border
early evening like the HRRR suggests. Am currently am leaning
towards keeping all mention of precipitation out of the forecast
in far southwest Kansas early this evening but will continue to
monitor things and adjust as needed.
For the rest of the overnight period...Models still are in
reasonably good agreement with moving an upper level wave across
the Texas Panhandle and southwest Kansas early tonight. As this
upper wave lifts northeast this evening a surface cold front will
begin to move north as a warm front back into southwest Kansas.
Also this evening 850mb warm air advection and moisture advection
will begin to improve north of this boundary, especially in south
central Kansas. This improving moisture and lift north of the
surface boundary along with some mid level instability overnight
could give way to a few showers and as a result will retain
mention of small chances of precipitation this evening east of
highway 183. At this time confidence is not high but the potential
does exist, especially in south central Kansas. Temperatures
profiles in this region early tonight also support that should
something develop it will mainly be in the form of rain. An
isolated rumble of thunder also can not be completely ruled out
near the Oklahoma border in south central Kansas.
Once this upper wave passes after midnight the surface boundary
will once again move south as a cold front into the Texas
Panhandle and Oklahoma. Skies will clear from from west to east
late tonight and early Monday as cold air returns behind this cold
front.Despite the clearing skies early Monday the temperatures
will stay on the cool side based on the 900mb to 850mb
temperatures at 21z Tuesday and 00z Wednesday. Based on these
temperatures in the 900mb to 850mb level the highs on Tuesday are
expected to range from the upper 20s along the I-70 corridor to
the lower 40s along the Oklahoma border.
.LONG TERM...(Tuesday night through Monday)
Issued at 158 PM CST Mon Feb 19 2018
An upper level trough will establish itself early in the week
across the western United States and then this upper trough will
move very little through late week. Over the next 5 days several
upper level waves will rotate around this upper level Western
United States trough and as each of these disturbances move from
the base of the upper trough and out into the central plains mid
to late week there will be a slight chance for some light
precipitation across south central and possibly even portions of
southwest Kansas. The chance for precipitation will be improving
late week and over the weekend as models hint at better moisture
and lift across western Kansas. This lift will be occurring north
of a surface boundary that will be located across the Texas
Panhandle and Oklahoma and ahead of the Western United States
upper level trough as it moves east towards the Central Rockies.
This will not only bring some improving chances for precipitation
late week and over the weekend period but also bring some warmer
temperatures back to western Kansas.
For temperatures this week...temperatures are expected to stay on
the cool side given the cooler air that will be filtering into
western Kansas behind the cold front tonight and Monday is
currently forecast to remain in place through at Thursday. Periods
of cloudy skies occurring each day will also be possible as a
series of upper level waves cross the Western High Plains. A
gradual warming trend will begin to occur Friday and continue over
the weekend as a surface warm front lifts north across Kansas.
Highs are expected to rebound from the 30s and 40s on Thursday to
the 50s and 60s on Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 500 PM CST Mon Feb 19 2018
Stratus has retreated northward temporarily late this afternoon,
with MVFR stratus cigs still being reported at Scott City and HYS.
With easterly upslope components, have high confidence that
stratus will return to DDC/GCK after sunset, with cigs lowering at
HYS. NAM forecast soundings performed well with stratus last
night, and followed their lead again with this TAF cycle. MVFR
cigs are expected, with periods of IFR, but surface visibility
should remain above 5-6 sm. Areas of BR or DZ are expected
overnight, mainly south of HYS and east of DDC. Dry advection at
the surface should minimize any drizzle/freezing drizzle impacts,
and kept it out of the TAFs for now. By 12z Tue, north winds will
increase to 17-27 kts at all terminals as cold air is reinforced
across SW KS. Stratus cigs will gradually lift Tuesday morning,
with VFR/SKC expected after 18z Tue.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 17 32 11 32 / 20 0 0 10
GCK 14 29 9 31 / 20 10 0 0
EHA 27 39 13 33 / 20 10 0 0
LBL 33 42 11 33 / 20 10 0 10
HYS 15 29 9 31 / 20 0 0 0
P28 27 37 17 33 / 30 10 10 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Turner
SHORT TERM...Burgert
LONG TERM...Burgert
AVIATION...Turner
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
939 PM CST Mon Feb 19 2018
.UPDATE...
First set of storms coming across the Seminole Canyon State Park in
west Val Verde County as of 930 PM this evening. More storms are
expected to develop tonight into the overnight hours as an upper
level short wave moves from northeast Mexico into Val Verde County
and southern Edwards Plateau overnight. There is enough instability
with surface to 6 km shear values of 50 to 60 knots for storms to
quickly develop and become strong to marginally severe. The main
hazards as these storms develop will be hail up to one inch in
diameter and thunderstorm wind gusts of 60 mph. Some quick and heavy
downpours could end up with one inch of rainfall accumulations.
&&
.PREV DISCUSSION... /ISSUED 519 PM CST Mon Feb 19 2018/
AVIATION...
Scattered showers have developed southwest of the San Antonio sites
and will begin these terminals with VCSH. A more robust complex of
showers and thunderstorms will develop west of DRT this evening and
will bring TSRA to DRT between 3z and 7z. This system will possibly
impact the I-35 sites around 9-15z and will mention VCTS for these
sites because of the lower probability. MVFR/IFR conditions are
expected again tonight with slow improvement anticipated in the
afternoon. Additional rain chances are expected tomorrow afternoon
with higher chances beyond the current TAF cycle.
PREV DISCUSSION... /ISSUED 338 PM CST Mon Feb 19 2018/
SHORT TERM (Tonight through Tuesday Night)...
A very active weather pattern through the short term forecast, with
first a chance of strong to severe storms tonight across the
northwest CWA and then a chance for locally heavy rainfall across a
good portion of the CWA Tuesday night into Wednesday morning. An
active sub-tropical branch of the jet stream will send multiple
disturbances through the region over the next 36 hours.
The first weak disturbance is currently generating a band of light
rain near the I-35 corridor, which continue to lift northeast through
the northern and eastern CWA through the remainder of the afternoon.
Forcing from a more potent upstream disturbance coming out of Mexico
and de-stabilization taking place along the Rio Grande, where
clearing has taken place, will generate convection across the higher
terrain of Mexico and the southern Edwards Plateau this evening.
Several HREF members, the HRRR, and TT WRF indicate a semi-organized
complex developing across the northwest CWA later this evening and
lifting northeast into the Hill Country overnight, as the convection
encounters a developing 40 kt low level jet and theta-e ridge. Deep
layer shear values of 50-60 kts, MUCAPE values of 1000-1500 J/kg, and
mid level lapse rates of around 6 deg C/km are supportive of some
strong to severe storms, mainly near and north of a Eagle Pass to
Medina, to Burnet line, where current SPC Marginal Day 1 risk is.
Main threats will be hail as well damaging straight-line winds,
should the convection become more organized. Can`t rule out a quick
1-2 inches of rainfall in some spots, but should be progressive
enough to limit potential for widespread flooding.
Farther east into the I-35 corridor, showers should be developing
beneath the inversion late in the night and into the Tuesday morning.
Can`t rule out some isolated elevated thunderstorms further east.
Majority of the guidances decays the semio-organized storms Tuesday
morning before reaching the I-35 corridor, however should note that
recent HRRR runs are trending closer to the I-35 corridor with the
convection. There could be some re-development of deeper convection
Tuesday afternoon across portions of the northern and eastern CWA.
TT WRF and GFS runs are indicating strong upward vertical motion then
developing late Tuesday night ahead of another impulse in the
southwest flow aloft. Recent runs of both models are indicating
widespread convection developing out of Mexico into the southwest CWA
late Tuesday night and then into a broad low level convergence area,
ahead of a cold front, across the Hill Country and I-35 corridor
overnight Tuesday into Wednesday morning. Forecast soundings are
favorable for locally heavy rainfall and training over some
locations. Forecast precipitable water values are forecast to be an
impressive 1.5-1.8" across central and eastern areas of the CWA,
which would be climatological maxes for this time of year. Should
note that run to run consistency, as well as NAM12 and ECMWF, are
adding to some uncertainty in exact placement of heavier banding, but
in general ingredients are coming into place for the potential for
pockets of heavy rainfall somewhere across the eastern 2/3rds of the
CWA Tuesday night through Wendsday morning. We have included a
mention of locally heavy rainfall into the forecast and will continue
to advertise 1-3 inches with isolated pockets up to 5 inches,
although as mentioned the pockets are difficult to determine at this
time. Day 2 and Day 3 Excessive Rainfall Outlooks from WPC continue
with a Slight Risk of exceeding flash flood guidance near and north
of I-10. A Flash Flood Watch could be considered tomorrow as forecast
confidence in placement of heavier banding increases.
LONG TERM (Wednesday through Monday)...
The aforementioned cold front eventually works through the CWA during
the day on Wednesday and undercuts the deeper convection. However
good chances for post frontal showers and isolated thunderstorms will
continue behind the front into Wednesday afternoon with falling
temperatures. Much cooler on Thursday with continued chances for
showers. The front works back north as a warm front Thursday night
and Friday, with warmer temperatures expected on Friday. Another cold
front is expected to move through the area on Saturday providing a
quick chance of showers and slightly cooler temperatures over the
weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 67 72 61 66 45 / 50 80 100 100 50
Austin Bergstrom Intl Airport 66 73 62 66 46 / 40 70 100 100 50
New Braunfels Muni Airport 66 73 63 69 47 / 40 70 100 100 50
Burnet Muni Airport 65 72 57 59 41 / 60 80 90 90 40
Del Rio Intl Airport 63 81 61 72 48 / 50 10 50 70 30
Georgetown Muni Airport 66 71 58 62 43 / 60 80 90 90 50
Hondo Muni Airport 67 78 64 71 49 / 50 50 90 90 40
San Marcos Muni Airport 66 73 62 68 46 / 40 70 100 100 60
La Grange - Fayette Regional 68 74 66 72 51 / 20 70 80 90 70
San Antonio Intl Airport 67 75 63 70 48 / 40 60 100 100 50
Stinson Muni Airport 67 76 64 73 50 / 40 60 90 100 50
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Hampshire
Synoptic/Grids...17
Public Service/Data Collection...YB
Area Forecast Discussion
National Weather Service Grand Forks ND
1001 PM CST Mon Feb 19 2018
.UPDATE...
Issued at 951 PM CST Mon Feb 19 2018
Light snow continues to move in from the southwest, with more seen
upstream all the way down to the Nebraska panhandle and
northeastern Colorado. Amounts so far have been pretty light, but
short range models as well as the 00Z NAM are pretty consistent on
bringing in another surge of moisture into the southeastern CWA
later tonight. There is some mid level frontogenesis, so several
tenths of an inch of QPF will be possible later tonight. The
question is just how much and if the second round follows the same
track as the first and leads to more accumulation. At this point,
running the expected QPF based on the blend of short range models
along with snow ratios near 20:1 gives snow amounts generally in
the 4 to 6 inch range across the current advisory area, with a few
spots over 6 inches. Still not confident enough to upgrade to a
warning, but will keep an eye on things for the next couple of
hours. Bumped up lows a few degrees as with clouds we are not
falling off as much as expected in the west.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 325 PM CST Mon Feb 19 2018
Not much change for this forecast period from our previous
package. Some light snow or flurries continue to brush some of
our westcentral MN counties this afternoon while clouds thicken
and lower over southeast ND... in advance of a more significant
moisture surge still working its way up through central SD. A hint
of the likely deformation band is currently setting up in an arc
from northeast SD into westcentral MN.
Model guidance is fairly consistent on placing band of QPF over
the tri-state border area in the 0.25 to 0.40 inch range. With
snow ratios likely to push from 18:1 to 22:1 through the period
there should be an area pushing 6 inches of snow or a bit more,
from near Aberdeen... through Fergus Falls... and past Park
Rapids. Heaviest snowfall there links peak moisture advection
with coolest boundary layer temps... from just after midnight
through Tuesday morning drive time.
For now... its looks as if the Lisbon-Fargo-Bemidji Line is
setting up as the north edge of that heavier (3 to 5 inch)
snowfall range, with snowfall likely to taper off fairly sharply
north of that line. Will remain to be seen if the heavier snow
band shifts further north as some of the HRRR runs show a bit of
variability. Thus have stuck with previous Winter Weather Advisory
outline and timing, but have split out the southern portion to
indicate the somewhat higher snowfall potential there.
System exits the area a bit more slowly on Tuesday than the
previous system, so some lingering low clouds and snow flurries
are likely after midday. Northwest winds will increase in the
late forenoon and afternoon, so some blowing and drifting is to
be expected in open areas.
.LONG TERM...(Tuesday night through Monday)
Issued at 325 PM CST Mon Feb 19 2018
Clearing skies and fresh snow will lead to a cold night on Tuesday
with dangerous wind chills. After this cold night a warming trend is
present through Sunday, with temperatures from Thursday through the
weekend temperatures near normal.
High pressure dominates until Thursday when the next chance for snow
arrives. An upper level trough and its associated surface low will
provide some light accumulating snow. There is fairly good agreement
between the GFS and ECMWF for this event. The best snow chances will
be from southeast North Dakota to north central Minnesota. High
pressure returns Friday into the weekend. There is still a clipper
passing nearby in the GFS in around Sunday but the ECMWF and CMC
have a different evolution in this period so there is significant
uncertainty.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 723 PM CST Mon Feb 19 2018
Ceilings are currently VFR across the forecast area but will begin
to deteriorate overnight. Conditions will drop to MVFR during the
06 to 12Z time frame as more moisture moves in from south along
with a band of light snow. The snow band will produce visibility
down to 1-2SM at times across all but KDVL. Think the heaviest
snow with vis below 1SM will stay to the south and east of TAF
sites. Snow will taper off by mid-day tomorrow and conditions will
improve to VFR at KDVL and KFAR by the end of the period. Winds
will be from the north at 10 to 15 kts, becoming northwest by
tomorrow afternoon.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Weather Advisory until noon CST Tuesday for NDZ038-039-
049-052-053.
MN...Winter Weather Advisory until noon CST Tuesday for MNZ002-003-
009-015>017-022>024-027>032-040.
&&
$$
UPDATE...JR
SHORT TERM...Gust
LONG TERM...NC
AVIATION...JR
Area Forecast Discussion
National Weather Service Fort Worth TX
912 PM CST Mon Feb 19 2018
.UPDATE...
Showers and some storms are beginning to blossom across the
region this evening as a 40 knot low level jet interacts with
increasing large scale lift. Other convection is now beginning to
fire across the Edwards Plateau. This is the activity we expect
to organize and move across the region late this evening and
overnight. Locations that see showers or storms will likely
experience gusty winds due to some evaporation and momentum
transfer from the low level jet. Since the strong and gusty winds
will be sporadic and dependent on the precipitation, we will not
issue a wind advisory at this time.
For this update, we will adjust temps/dewpoints and winds slightly
and blend the evening and overnight PoPs into the 60% to 80%
range.
79
&&
.AVIATION... /Issued 634 PM CST Mon Feb 19 2018/
/00Z TAFs/
Weather challenges abound with only marginal confidence regarding
timing with lower cigs tonight and rounds of SHRA/TSRA later
tonight and through Tuesday.
Currently, scattered very light showers extended from KF00, to
KF46/KHQZ, to KACT and KTPL this hour. Recent PIREP from 10SE of
KDAL reported moderate turbulence around FL100 and another right
over KDAL at FL180, likely from evaporation occurring from dry
pockets aloft on our very recent 00z FWD sounding. Both Bonham and
Cedar Creek cornerposts will be affected by this process and
further turbulence this evening, or until increasing ascent later
tonight can saturate these layers. Otherwise, occasional gusty
south winds will continue through the night in advance of a
shortwave aloft and any SHRA/TSRA, due to a strong surface
pressure gradient and semi-mixing of 40-45 knot 925mb winds that
may increase by another 10 knots by midnight.
VFR cigs will slowly fall into MVFR by mid evening, as gradual
boundary layer cooling occurs and we remain in a lull between mid
level disturbances. High-resolution models are in agreement for
some spotty -SHRA through 08z-09z, before a weakening convective
system approaches from the west. Though models project some weaker
instability toward the I-35 corridor by 12z, there will be surface-
based CINH further east, so it`s hard to say whether wind gusts
will be an issue if convection does truly become elevated. If they
do, then small hail, lightning, and occasional heavier TSRA would
be the main issues. All said, the window of 10z-13z appears to be
the window of greatest certainty of impacts for DFW Metro
airports.
As for Waco Regional, the gusty south winds will be generally the
same across Central Texas. Only differences will be convection
possibly starting an hour or two later and lingering a few hours
longer til 15z, as the stronger forcing moves further northeast
away from this area.
05/
&&
.SHORT TERM... /Issued 312 PM CST Mon Feb 19 2018/
/Through Tonight/
Main focus through the short term will be the convective chances
this afternoon and overnight. While the severe potential still
looks limited, a few strong or marginally severe storms can`t be
ruled out, mainly during the overnight hours west of I-35.
A deep trough has taken shape over the western US with a
strengthening surface low located in Colorado. To the east, a
stalled cold front lies in a pressure trough draped through the TX
Panhandle and OK northeastward into KS and MO. To the south a
very warm and humid airmass is in place within a strong southerly
flow regime. Several days of south flow have caused rich Gulf
moisture to overspread the area with near-record PW values of over
1.5" now in place. As shortwaves ripple through the parent
trough, scattered showers and storms will be likely, also aided by
weak ascent from warm advection. Precipitation is starting to
increase slightly as of 3pm primarily along and just east of the
I-35 corridor. This is occurring within the axis of greatest
moisture content where there is also strong warm advection.
Through the evening, would expect a gradual increase in showers
with isolated embedded lightning strike near the I-35 corridor.
South winds will also remain gusty into the evening at 20-30 mph.
Meanwhile, in West Texas, a cluster of showers and thunderstorms
is expected to develop in vicinity of the dryline in the next few
hours which will move northeastward. The exact evolution of this
convection remains uncertain, but indications are that this
cluster of storms will be capable of progressing into our forecast
area counties late this evening. Depending on the organization of
this line, it could potentially pose a threat for some 50+ mph
wind gusts and at least some small hail. Stronger storms will be
more likely if the cluster is able to organize into a broken QLCS
structure, which given the strong shear in the 0-3km layer, seems
plausible. Storms should also have about 1000 J/kg of MUCAPE to
work with. The HRRR remains the most bullish on this overnight
convection, while other high-res guidance keeps it less organized
and weaker. One factor working against these storms will be
increasing CINH through the evening, therefore storms should be
forced to become elevated. This should help lessen the wind
threat, but since synoptic low-level winds are already 50+ knots,
mixing down this momentum to the surface wouldn`t be too
difficult for some strong downdrafts to achieve. Given the strong
shear in place, also wound`t be surprised to see some small hail,
probably remaining below severe limits. Convection should continue
an overall weakening trend as it approaches the I-35 corridor
between midnight and sunrise. The best chance for stronger storms
will be west of I-35. The flood threat with this initial batch
will be low since it will be fast-moving. Rain amounts are
expected to be less than an inch for most areas through Tuesday
morning.
Otherwise, the gusty south winds will continue into Tuesday
morning along with a broad area of showers and embedded
thunderstorms. Skies will remain mostly cloudy with rich moisture
continuing to stream in from the south. The additional waves of
rainfall and ensuing potential for heavy rain/flooding are
discussed below.
-Stalley
&&
.LONG TERM... /Issued 312 PM CST Mon Feb 19 2018/
/Tuesday through this weekend/
An active weather pattern is setting up for the week and will be
defined mainly by a deep upper trough over the Rockies and an
upper ridge over Florida. This pattern will leave North and
Central Texas susceptible to periods of strong lift generated by
disturbances in the southwest flow aloft. Scattered showers and
thunderstorms will likely be ongoing Tuesday morning as an initial
shortwave lifts northeast across the Southern Plains. Shear and
instability will be sufficient for a few strong storms early
Tuesday, but the convective mode should gradually shift to a warm
advection showers/isolated thunderstorms regime later in the day as
the shortwave exits to the northeast.
The passing disturbance will help force a cold front south
across the Red River Tuesday night. The front will slow and
possibly begin to stall as it sags south of the I-20 corridor.
Meanwhile, large scale ascent will be on the increase as the upper
low digs south into the Four Corners region. There could be a
lull in precipitation Tuesday night, but convection will ramp up
on Wednesday as ascent increases and the front provides added
focus for development.
An unusually moist airmass will be in place this week,
particularly along and east of the Interstate 35 corridor where
PWATs in the 1.50-1.75 inch range will exist. This could be
problematic regarding flooding potential as it appears that the
front will become quasi-stationary somewhere across the east or
southeast counties.
Model QPF is somewhat variable, but Tuesday through Wednesday
night rainfall totals between 2 and 4 inches are looking
reasonable across a good swath of the central and eastern zones.
Localized higher totals will be possible in the vicinity of the
surface front. Higher totals are not out of the question in the
cold sector as well, especially if there are any training
thunderstorms. For this reason, a Flood Watch will be issued for
areas generally along and east of Interstate 35.
Since convection is expected to increase in coverage and intensity
late this evening and overnight, the Watch will begin Tuesday
morning as locally heavy rainfall may already be in progress.
Another shortwave will lift northeast across the region Tuesday
night through Wednesday. At this time, we have the Watch expiring
at midnight Wednesday night, after-which the shortwave will exit
to the northeast and a lull in precipitation is expected.
Another issue that we will continue to monitor is the possibility
of freezing rain or freezing drizzle across the northwestern-most
counties Tuesday night. This area will be west of the heavier
precipitation, but will also see the coldest temperatures in the
post-frontal airmass. The latest guidance indicates that low
temperatures will be right around freezing Wednesday morning when
light precipitation will still be possible. The current thinking
is that after the recent warm weather, the likelihood of any
accumulations and resulting impacts is low. If later guidance
trends colder, some freezing rain may need to be added for a few
counties during the late tomorrow night/Wednesday morning period.
After a lull in precipitation Wednesday night and Thursday, convection
will ramp up once again Thursday night into Friday as the next
shortwave rounds the base of the Rockies upper low and lifts
across the Southern Plains. The potential for locally heavy rain
will exist as models are indicating PWATs back up around 1.50
inches. Precipitation should finally come to an end Sunday as the
entire upper level system works its way east across the Plains,
with dry and seasonable weather expected Sunday through the early
part of next week.
30
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 67 72 43 45 39 / 80 80 70 70 40
Waco 65 72 49 53 41 / 80 80 80 80 50
Paris 64 71 46 50 43 / 80 80 80 80 60
Denton 66 72 39 43 36 / 80 80 50 70 40
McKinney 66 71 41 46 39 / 80 80 70 80 50
Dallas 67 72 43 46 41 / 80 80 70 80 50
Terrell 67 72 46 51 42 / 80 80 80 80 60
Corsicana 66 71 49 54 45 / 70 80 80 80 70
Temple 65 71 51 55 42 / 80 80 80 80 50
Mineral Wells 63 74 39 42 33 / 80 80 40 60 30
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 6 AM CST Tuesday through Wednesday evening for
TXZ093>095-103>107-118>123-133>135-144>148-159>161.
&&
$$
79/05
Area Forecast Discussion
National Weather Service Wilmington NC
1031 PM EST Mon Feb 19 2018
.SYNOPSIS...
Record warmth slated for the upcoming week. A warm front will
move north of the area by mid-morning Tuesday. Bermuda High
pressure will ridge in from the east and bring temperatures well
above normal this week with possible record warmth Wednesday
and Thursday. A cool front will drop towards the area Friday but
likely stalling just to our north. The Bermuda High will again
expand over the region for the upcoming weekend. A cold front
will approach from the northwest late Sunday night and may stall
across the region Monday.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 930 PM Monday...Have raised a Dense Fog Advisory for the
entire ILM CWA, in effect now thru 10 am Tuesday.
Have not had too many opportunities this winter in forecasting
CAD events as well as inland progressions of coastal and warm
fronts respectively.
A coastal warm front had recently pushed onshore and now
extends from Elizabethtown to Florence. With a saturated low
level atm, light to calm winds and a semi-stalled boundary in
the vicinity, areas of fog quickly developed after sunset over
land areas. The fog further dropped to dense criteria
especially across locations that show very limited mid and high
level clouds present. The dense fog remains quite shallow with
the ILM Tower indicating vsby at 6 miles above the sfc based fog
layer. Model guidance and latest sfc obs trends indicate the
patchy dense fog at the moment should transition to areas of
dense fog by midnight and pretty much staying that way possibly
up to mid daytime morning Tue. The area from Little River Inlet
eastward will see occasional isolated light and brief showers
move onshore overnight basically traveling along the periphery
of the expanding Bermuda high. Vsbys may briefly improve but
will drop back to dense criteria. Some tweaks applied to
tonights lows as well as both the hourly temps and dewpoints.
Previous......................................................
As of 3 PM Monday...It`s been easy to find the warm front
today, outlined by a 20-degree difference in temperature and an
almost 180- degree difference in wind direction. The front
pushed onshore across SE North Carolina where Wilmington reached
75 degrees before noon, but temperatures have so far stayed in
the 50s in Florence, Darlington and Lumberton. A persistent
stream of clouds and light showers linked to moisture advecting
in from the Gulf Stream off the South Carolina coast has
produced waves of light showers across Myrtle Beach and up
through Whiteville and Elizabethtown this afternoon. This rain
should weaken with time as it slips into the Cape Fear area
early this evening.
The high-res models have performed quite well with the frontal
position today. The NAM, RUC, and HRRR correctly depicted cool
inland temperatures and northerly wind directions, while the
GFS and ECMWF were rather clueless. All models show shallow low
clouds developing across the entire area tonight as tropical
moisture continues to advect overhead. Stratus clouds may settle
down to the surface becoming fog overnight, perhaps even dense
at times. Although no dense fog advisory will be issued yet,
we`ll highlight the potential in the Hazardous Weather Outlook.
Overall depth of the stratus may be a little too shallow for
drizzle.
The sun should burn through the clouds and fog by late Tuesday
morning, jumping the warm frontal position well inland. As the
nearly tropical airmass, now down at the surface, is warmed by
the sun look for Tuesday`s highs to approach 80 degrees inland.
The beaches may do good to touch 70 degrees for highs with a
relatively cool southerly wind across the ocean. Areas of sea
fog lingering offshore could reach the beaches at times Tuesday
afternoon but should dissipate very quickly after crossing
inland.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 3 PM Monday...Short term to be characterized by
unseasonable warmth. Temperature deviations from climatology
will be about 20 degrees by both day and night making lows
warmer than seasonable highs. As for Wednesdays highs in the
upper 70s coast low 80s inland could be poised to break some
records depending on ocean influence. Record highs for 2/21:
ILM: 78 from 2014.
FLO: 81 from 1997.
CRE: 76 from 1953.
The former appear to be in trouble while CRE will be dealing
with SSE onshore flow of the marine layer. Speaking of the
marine layer, models are still showing areas of sea fog through
a good part of the period. SREF VSBY<1nm probs maxing out over
SC areas and have for a while now and this seems plausible. This
moisture will occasionally affect areas along the Grand Strand
and also make for some temperature forecast complications.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 3 PM Monday...Continues to look like a period of extended
warmth with potential for record breaking temperatures this week.
Bermuda High and 5h western Atlantic ridge team up to bring an
extended period of warm southerly flow and mid-level subsidence.
GFS continues to slowly back away from bringing a backdoor cold
front into the area Thu night and Fri. Meanwhile the Canadian,
ECMWF, and WPC all have the front stalling out around the NC/VA
border. Given the GFS is trending in this direction and mid-
level ridging tends to win out went ahead and removed any hint
of a front moving into the area Thu night and Fri. Next shot at
rainfall looks to be Sun night as cold front moves in from the
northwest. Front lacks a strong cold push and the ECMWF stalls
it in the region while the GFS passes it cleanly. Looking at the
predicted upper pattern would think the front stalled in the
area is probably more likely and for now will carry the Sun
night chance pop through Mon. The dynamics associated with the
front pass northwest of the area and forcing Sun night would be
limited, curtailing rainfall amounts. Might have a better shot
on Mon if the front ends up stalled and shortwave activity can
get involved, but have low confidence for the start of next week
at this point.
Partial thickness and 850 temps through the end of the week
suggest highs in the upper 70s to low 80s for areas not along
the immediate coast. Southeast to south flow will lead to a
strong sea breeze that will become a modified resultant as the
winds veer to south- southwest late in the period. Onshore flow
and water temps in the mid to upper 50s will keep highs at the
beaches in the mid to upper 60s at best. Front moving into the
area Sun night/Mon will drop temps a little. Even so most areas
are likely to end up close to 10 degrees above climo. Lows will
be even warmer with potential for lows 25 degrees or more above
climo.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
As of 00Z...Low confidence forecast. Currently VFR inland
terminals and MVFR with patchy light showers coastal terminals.
KMYR has had tempo bouts of 300-400 foot cigs through the
afternoon until TAF issuance time. This could be indications
sea fog is more persistent than satellite imagery indicates.
Showers will continue at the coastal terminals overnight but
become more isolated. Winds will be very light overnight all
terminals, thus fog is expected to develop. Cloud cover will
help prevent any real dense fog through 06Z, except at
KCRE/KMYR where IFR/LIFR could develop this evening if sea
fog continues to develop and spread. KILM should be far
enough away from the coast to escape the sea fog. After 08Z IFR
conditions are more likely to develop at KFLO/KLBT/KILM and
persist through 14-15Z, with a low possibility of LIFR.
Fog should lift to MVFR by mid morning with VFR by noon. The
exception will be KCRE where sea fog could persist into the
afternoon. Winds will be southeast to south 5-10 kt.
Extended Outlook...VFR. Morning IFR/BR possible Tuesday-Thu. Sea
fog possible through Thu but confidence is low.
&&
.MARINE...
NEAR TERM /THROUGH MONDAY/...
As of 930 PM Monday...Dense sea fog has expanded across the
local waters and as a result a dense fog advisory has been
issued for all waters til noon Tuesday.
Winds and seas will not be the issue for Mariners tonight or the
next few days. It will be the dense sea fog. With SSTs in the
mid 50s and sfc dewpoints in the mid 60s advecting across
theseshelf waters, the outcome is for the development of sea
fog. Satellite imagery, specifically GOES East channel
difference, ie. the 10.3-3.9 micron, illustrates the sea fog
nicely across the local waters as well as the inland fog. And
has become a very helpful tool especially across locations that
do not have a dense network of observations, like the coastal
waters.
Winds generally around 10 kt from the SE-S. And seas 2 to 3 ft
and mainly comprised of 4 to 6 second wind waves.
Previous......................................................
As of 3 PM Monday...A warm front moved across the coastal waters
this morning and has pushed inland across the Cape Fear area.
Variable winds remain along the Grand Strand coastline with the
front still stalled 5-10 miles out, and we don`t really
anticipate seeing solid southeasterly winds develop along the
Grand Strand beaches until late tonight when the front finally
jumps onshore. In terms of model guidance preferences, the NAM
model has been far outperforming the GFS with wind directions
today.
Mainly southeasterly winds should become southerly on Tuesday around
10 knots. Seas 2-3 feet should change little through Tuesday. As
tropical moisture continues to move across the cold nearshore
waters, the potential for areas of sea fog will remain in the
forecast through tonight and Tuesday. The limiting factor with sea
fog may turn out to be the overwhelming warmth of the incoming
airmass, perhaps not allowing the cold water to successfully cool
air down to its dewpoint. No dense fog advisory will be issued at
this time, although some potential does remain.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 3 PM Monday...A quiet and unchanging set of conditions
through the period. High pressure off the coast to bring a
southerly wind of just 10kt with a few occasional higher gusts.
Seas will average right around 3 ft.
LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 3 PM Monday...Bermuda High will maintain southerly flow
through the period. Weak backdoor front will try to drop in from
the north Thu night into Fri but appears the boundary will
stall out near the NC/VA border. Gradient will be on the weak
side with winds 5 to 10 kt Thu and Fri. High strengthens a bit
for the weekend with gradient becoming a little more defined as
inland areas warm up. Southwest flow on Sat will be closer to 10
to 15 kt. Seas 2 to 3 ft Thu and Fri build to 3 to 4 ft Sat as
winds become southwest and increase in speed.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Dense Fog Advisory until 10 AM EST Wednesday for SCZ017-023-
024-032-033-039-054>056-058-059.
NC...Dense Fog Advisory until 10 AM EST Wednesday for NCZ087-096-
099-105>110.
MARINE...Dense Fog Advisory until noon EST Wednesday for AMZ250-252-254-
256.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH/TRA
SHORT TERM...MBB
LONG TERM...III
AVIATION...MRR
MARINE...
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
739 PM CST Mon Feb 19 2018
.UPDATE...
Issued at 739 PM CST Mon Feb 19 2018
Just finished a significant update to PoPs for the rest of
tonight. We are in a "lull", but we are not anticipating the
current situation of widespread light freezing drizzle and snow to
end before the next wave gets here after 6z, so basically dropped
80+ pops in for the rest of tonight across the entire MPX area.
As for the snowfall forecast, did lower totals by about an inch
for our western tier of counties as the deformation band has setup
just west of our CWA this evening, with the HRRR and HopWRF both
pushing the 4 to 6 inch type snow totals west of the MPX coverage
area.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 250 PM CST Mon Feb 19 2018
The afternoon regional radar which was overlaid with the day
cloud phase satellite imagery (RGB), showed the wavy elements of
the clouds, which correlated nicely with the higher reflectivity.
These enhanced returns on the radar are related with an elevated
warm air advection regime, and a upper jet core moving across the
Upper Midwest. Although surface observations had only indicated
some light snow, mixed with freezing rain or sleet, I wouldn`t be
surprised to see some of the enhanced returns on radar having
heavier sleet, or some heavier snowfall for the next couple of
hours.
The forecast tonight, and into Tuesday morning will be based a
strong short wave moving out of the Rockies, and a pronounced
thermal gradient aloft indicating a mixed bag of precipitation in
the far southeast 1/3 of MPX forecast area.
The precipitation type issue is based on a very pronounced dry
layer initially which coincides with the lack of ice formation in
the clouds. Not until late tonight will the atmosphere moisten up
again to get into the preferred dendritic growth zone region, or
at least cold enough in the moist layer to generate ice vs
supercooled liquid water.
Most models support an increase in lift/moisture in the dendritic
growth zone region after midnight in southwest Minnesota. This area
will spread rapidly northeast across southern/central Minnesota, by
3 am, and into west central Wisconsin by 6 am. Models are also
indicating steeper lapse rates (700/500 MB aloft) developing
overnight. Thus, I wouldn`t be surprised to see some thunder in far
southern Minnesota after midnight. This scenario of thunder is also
supported in the forecast WRF models that have higher reflectivity
moving into southern Minnesota between midnight and 6 am.
Precipitation type is the main concern in far south central,
southeast Minnesota, as well as portions of west central Wisconsin
tonight. This is related to the 0C thermal boundary (Aloft) that
moves northward once again ahead of the next short wave tonight.
QPF amounts are not overly heavy through Tuesday morning, but the
majority of the precipitation occurs in a 3 to 6 hour time frame.
So, locally moderate to heavy snowfall is possible where the best
energy/lift coincides with the dendritic growth zone in west
central/central Minnesota. Where the precipitation type is mixed,
snowfall amounts will be much lighter with a coating of ice from
Albert Lea, Minnesota, northeast to Eau Claire, Wisconsin.
.LONG TERM...(Tuesday night through Monday)
Issued at 250 PM CST Mon Feb 19 2018
The long term period will feature below normal temps for the middle
of the week, a likely light snow event for Thursday night, and
temperatures warming to near or even slightly above normal for the
weekend and into early next week.
By tomorrow evening, the system will have departed to the east, with
the cool down underway. Surface winds will have turned
northwesterly, and a cool canadian high pressure will be moving in
from the northwest. Clearing skies and the arrival of a colder
airmass (in addition to fresh snow cover for some of the area) will
allow temperatures to drop below zero for much of the area. With
the high in place for Wednesday, expect plenty of sunshine, but
temperatures held around 15 to 20 in areas with snow. Western MN
and western WI will likely see temepratures 5-10 degrees warmer
due to the bare ground and more widespread tree cover.
Thursday will begin quiet, with the high departing to our east and
southerly winds developing. Meanwhile, the longwave trough
across the western CONUS will become quite amplified and positively
tilted, putting us in a southwest flow pattern. By Thursday night,
a shortwave trough will eject from the southwest CONUS on a
northeast course, with a likely light snow event expected. This
will be a quick moving wave with warm air advection enhancing lift
along with a strengthening upper jet. It still looks to be a 1 to
3" of snow type of event.
Moderating temepratures will continue from Thursday right into the
weekend as the zonal pattern keeps the bitter cold to our north. By
the weekend, high temperatures should reach the mid 30s, a few
degrees above normal. The pattern for the weekend typically means
more active weather for the middle of the country, and another
shortwave does eject from the southwest again on Saturday. The
models diverge with this system, so currently confidence is low in
its path. The ECMWF would bring light snow through much of southern
MN, while the GFS keeps it well south. Following a blended approach
of this with the forecast reading a chance of snow for much of the
area Saturday afternoon-night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 634 PM CST Mon Feb 19 2018
We are in our "lull" between heavier precip bursts. Unfortunately,
this will not mean there will be no precip. Instead, we look to be
in a steady state situation until the next wave arrives. This
means a mix of fzdz/sn for all but AXN/STC for the first several
hours of the TAF. Followed the HRRR for timing next wave in. Will
be a fast mover, moving through the MPX area between 7z and 11z.
P-type will be similar to what we saw mid-day Monday, a
snow/pellet mix, more snow for RWF/STC trending to more pellet for
EAU. For AXN, it`s all snow, and could be quite heavy at that
between. Snow may linger into the afternoon at AXN, but will end
quickly in the morning everywhere else. No significant
improvements in cigs are expected until between 00z and 06z
Wednesday.
KMSP...Fairly high confidence in this TAF with several hours of
fzdz to start, followed by another burst of SN/PL around 8z.
/OUTLOOK FOR KMSP/
Wed...VFR. Wind W 5 kts.
Thu...VFR in mrng, MVFR or lower in aftn. Chc IFR/-SN late. Wind
SE 5-10 kts.
Fri...MVFR. Chc IFR/-sn. Wind W 5 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until noon CST Tuesday for WIZ014>016-
023>028.
MN...Winter Weather Advisory until noon CST Tuesday for MNZ041>045-
047>070-073>078-082>085-091>093.
&&
$$
UPDATE...MPG
SHORT TERM...JLT
LONG TERM...SPD
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
640 PM EST Mon Feb 19 2018
.SHORT TERM...(This evening through Tuesday)
Issued at 421 PM EST MON FEB 19 2018
Water vapor imagery and RAP analysis show a deep trof over the
western CONUS (500mb height anomalies of 300m) and strong ridging
over the eastern CONUS (500mb anomalies of 300m over the ne). Result
is sw flow into the Upper Lakes. Although no significant shortwaves
are noted in the sw flow, upper jet dynamics and low/mid level fgen
are taking advantage of abundant moisture (precipitable water per
12z raobs was around 200pct of normal at KMPX/KGRB) to support areas
of pcpn across the Northern Plains to Upper Lakes. Focused fgen for
much of the day led to a band of mdt/hvy snow from nw WI to the
Houghton vcnty. Houghton area has probably had around 4in of snow
since mid/late morning.
SW mid level flow will remain in place thru the short term. With a
lack of any significant shortwaves lifting out of the western trof,
pcpn will continue to be largely driven by upper jet dynamics and
low/mid level fgen. Fgen supporting the heavier snow over nw Upper
MI is fcst to fade away this evening. Hvy narrow band of snow from
the morning/early aftn is already dissolving into a broader area of
mdt snow so that diminishing trend is underway. Meanwhile, there is
generally a consensus for a push of isentropic ascent across the
area this evening. As a result, pcpn should be more widespread thru
the evening hrs before diminishing in intensity and coverage. Pcpn
will probably become patchy overnight. In general, moisture depth
tends to diminish with time tonight in addition to continued waa
pushing an elevated warm nose above 0C northward into central and
eastern Upper MI. This should will lead to ptype becoming more
-fzra/-fzdz dominated with time. Sheared out shortwave will lift ne
across MN into northern Ontario on Tue. This may support another
period of more widespread pcpn Tue morning before pcpn diminishes
and mostly ends w to e in the aftn. Overall, ice accumulations over
the se half are likely to be under one-quarter inch and mostly one-
tenth to two-tenths of an inch...probably closer to the lower end of
that range. Ice accumulations will be less that that over the w.
Snow accumulations should range from less than 1 inch se to 2 to 4
far nw. Per coord with surrounding offices, advy for the central
will run until 00z Wed, but with pcpn largely done by 18z, will
likely be able to cut the advy end time back with later updates.
.LONG TERM...(Tuesday night through Monday)
Issued at 242 PM EST MON FEB 19 2018
More active winter weather possible late this week into next weekend
as general troughing over west half of Conus contiues to send systems
toward Great Lakes.
Active weather occurring early this week settles down considerably
as early as Tue night as sfc low exits into Quebec and quasi
stationary boundary moves to the lower Great Lakes. High pressure
over northern Plains then builds over western Great Lakes through
Wed. Colder air (h85 temps down to -18c) works in on northwest low-
level winds so there may be light lake effect for northwest to west
flow snow belts. However, do not expect much LES this time around
since area is within dry slot of H85 low lifting toward James Bay
resulting in minimal large scale low-level moisture. Another
negative for LES is expansive ice on western Lk Superior. Will only
have slight chance pops for mainly the Keweenaw late Tue night into
Wed morning. Expect partly to mostly cloudy skies along Lk Superior
and east for much of the day but skies should clear out Wed night.
High pressure and light winds along with pwats less than 0.10 inch
point to min temps dropping well below zero inland. Used colder WPC
and GEM bias corrected guidance.
High pressure will keep conditions dry over Upper Michigan on Thu
though increasing high clouds will signal the return of another
system lifting into the region from the central Plains. Shortwave
and area of q-vector convergence with H85 wave and moisture
advection appear to be main drivers for the light snow. Not much
enhancement coming from upper level jet as its primary lifting
influence stays south and east of here closer to sfc front and
baroclinic zone. Real good agreement from model qpf and GEFS
ensembles for a 6-12 hour period of light snow with QPF amounts
staying less than 0.25 inch. SW flow ahead of H85 low tries to bring
warmer air into the western Great Lakes, but right now looks like it
stays cold enough for just snow as ptype across all of Upper
Michigan.
After a break on Sat, another system could move in late Sat night
into Sun as shortwave trough rides across the Great Lakes downstream
of broad trough aloft over west half of Conus. There are expected
model differences that far out though. Main difference is GFS taking
shortwave/sfc low farther south across the Ohio valley while
ECMWF/GEM and GEFS would bring system farther north across central
Great Lakes. Latest GFS continues to keep U.P. dry on Sun while
other guidance has at least light qpf over much of Upper Michigan.
ECMWF would even bring moderate qpf over 0.25 inch across parts of
Upper Michigan. Probably stays cold enough for just snow for this
system as well. Another weaker system may move in on Monday, but
there are too many differences to go with anything more than slight
chances. Other than chilly night Wed night, temps through the long
term should be normal or even above normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 638 PM EST MON FEB 19 2018
IFR conditions (vis and/or cigs) will mostly be the rule into Tue
morning this fcst period at KIWD/KCMX/KSAW as waves of pcpn move
ne across the Upper Lakes. While pcpn should be only snow at
KIWD/KCMX, snow at KSAW will likely mix with or change to -fzdz at
times tonight thru Tue morning. May even be a period of only
-fzra Tue morning. Expect slowly improving conditions Tue
afternoon as pcpn generally ends and cigs rise to low end MVFR.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 242 PM EST MON FEB 19 2018
May see northeast gale gusts to 35 knots over western sections of Lk
Superior through tonight. Otherwise, winds are expected to stay
below gales the rest of the forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 7 PM EST /6 PM CST/ Tuesday for
MIZ004>007-010>014-085.
Winter Weather Advisory until 1 PM EST /noon CST/ Tuesday for
MIZ001>003-009-084.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...JLA
AVIATION...Voss
MARINE...JLA
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Tuesday)
Issued at 305 PM CST Mon Feb 19 2018
An upper level trough across the southwestern US will lift
northeast across the central plains on Tuesday. The surface
cold continued to push southeastward across southeast KS
into southwest MO. As the upper level trough begins to lift
out into the central and southern high plains Tonight, a lee
side surface low will deepen across southeast CO. This will
cause the front across extreme southeast KS and southwest MO
to become stationary and even lift northwest towards the
southeast counties of the CWA, so temperatures across areas to the
south of I-35 may warm into the 40s and even some 50 degree
temperatures across Anderson CO. Meanwhile the shallow cold
airmass across the central and western counties of the CWA will
only modify slightly and temperatures will remain in the upper 20s
to lower 30s. As 850mb winds back more to the south, we`ll see
deeper 850mb moisture advect north-northeast across the CWA. The
resulting isentropic lift and large scale ascent ahead of the H5
trough will cause rain and perhaps some elevated thunderstorms to
develop across south central KS, then expand northeast across the
eastern half of the CWA through the night. Areas at or below
freezing may see periods of freezing rain Toning, generally along
and west of a Holton to Council Grove line. The far northwest
counties may only see freezing drizzle as the ascent and moisture
may stay just east of the western counties of the CWA. I think
much of east central KS will see temperatures warm into the upper
30s north of I-35, which should keep precip in the form of rain
for TOP, LWC, and EMP. There may be enough instability for
elevated thunderstorms to develop along and southeast of the KS
turnpike Tonight.
Through the early morning hours the stronger ascent will shift
northeast and a surface low will develop across southern MN in
the vicinity of the left exit regions of the 90KT H5 jet max.
This will result in stronger CAA across SD and NE and bring a
strong push of arctic air southeast across the CWA during the
morning hours. The 12Z NAM is much colder with temperatures than
the other numerical models and would keep freezing rain going
through the night for areas along and northwest of the KS
turnpike. Other models modify the shallow cold airmass across the
CWA this afternoon and slowly warms all of east central KS above
freezing through the evening hours and into the night before the
stronger CAA shifts southeast across the CWA from 12Z through 18Z.
The NAM, RAP and ARW show temperatures dropping below freezing
along and west Oskaloosa, to Topeka, to Emporia line by 12Z TUE.
This area may also see the steadier stratiform rain which may
produce up to 0.2" of ice accumulations from western Jefferson
County, northern and western Shawnee, Wabaunsee and northern and
western Lyon counties. This may occur right during the morning
rush hour, so I will expand the current winter weather advisory
east by one row of counties, then southward against the ICT CWA.
I`ll keep the time the same in case temperatures do not warm above
freezing, there is still some uncertainty in temperature trends
and QPF. If any elevated thunderstorms develop in the areas that
remain below freezing, then ice accumulations in some areas may be
higher than forecasted.
Tuesday, as the lead H5 trough lifts northwest across the plains
into the upper midwest. A longer wave length trough will continue
across the western US. The freezing rain will shift east into MO
during the late morning and early afternoon hours. There could be
some minor glaze of ice across the remainder of the east central
KS during the mid and late morning hours before the precip ends.
Highs on Tuesday will only reach the upper 20s across north
central KS with lower to mid 30s across much of the remainder of
the CWA. The southeast counties may have morning highs in the
upper 40s to around 50 before temperatures fall back into the 30s
during the afternoon hours.
.LONG TERM...(Tuesday night through Monday)
Issued at 305 PM CST Mon Feb 19 2018
Tuesday night through Thursday, another upper level trough will
dig southeast into the southwestern US and lift northeast across
the plains on Thursday. Ahead of the H5 trough deeper 850mb
moisture will advect northward across the CWA which will result in
another round of freezing rain. The vertical temperature may
start out cold enough across north central KS for snow but the
snow will transition to freezing rain as a warm nose advects
northeast between 850-700mb. We could see periods of freezing rain
or drizzle lasting through Noon on Thursday before the precip
ends. Lows Wednesday night will be in the teens and 20s. Highs
late Thursday afternoon will be in the lower 30s across north
central KS with mid to upper 30s across the remainder of the CWA.
Friday, we`ll see drier weather with highs reaching the lower to
mid 40s. A third upper level trough will dig southeast into the
southwestern US.
Friday night and Saturday, The upper trough across the southwestern
US will lift northeast into the plains Friday night into
Saturday. There could be another round of freezing rain changing
over to sleet and snow as the H5 trough axis lifts northeast
across KS on Saturday. The precip should end Friday afternoon and
High may reach into the 40s if we see some insolation.
Sunday through Monday, the mid to upper level flow will become
zonal. A lee surface trough will deepen across the high plains
which will cause surface winds to become southerly. High
temperatures will warm into the 50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 511 PM CST Mon Feb 19 2018
MVFR ceilings are currently in place with drizzle expected to
reach the surface in the next few hours. Temperatures should below
freezing at all the sites once the drizzle starts. A round of
freezing rain is forecasted to begin late this evening and
continue until late morning with some lulls possible. Ceilings
might drop to IFR during the freezing rain. The stratus might
actually begin to clear out tomorrow afternoon. Low level wind
shear will be an issue with changing wind directions from north at
the surface to south around 2 kft.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Tuesday for KSZ009>012-
021>024-026-034>039-054.
&&
$$
SHORT TERM...Gargan
LONG TERM...Gargan
AVIATION...Sanders