Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/01/20
Area Forecast Discussion
National Weather Service La Crosse WI
551 PM CST Fri Jan 31 2020
.SHORT TERM...(Tonight through Sunday)
Issued at 240 PM CST Fri Jan 31 2020
Upper level low with attendant bits of energy shifting slowly
east/southeast across the area this evening, and will continue to
spark areas of light pcpn. Mostly snow expected, but there will be
some loss of ice in cloud (per RAP bufkit soundings) that point to
freezing drizzle. Amounts of snow and/or icing (if freezing drizzle
is realized) will be minimal.
Mild weekend for the region as upper level ridge builds in. 850mb
temps progged to reach as much as +7C Sunday with NAEFS 850 mb temp
anomalies still hovering around +2. EC ENS anomalies are a bit
higher than that. Decent shot to hit 50 for highs in some locations
(mostly southwest WI). The warm up will be short lived with
colder, more seasonable air returning for the new work week.
While many will welcome the mild conditions, the warmth will melt
some of the existing snowpack, with runoff into the local water
ways. Could get some rises on a few rivers as a result. If warmth
was more than just 1 to 2 days, concerns would increase for possible
ice jamming and the potential for flooding. Still, something to
monitor.
.LONG TERM...(Monday through Friday)
Issued at 240 PM CST Fri Jan 31 2020
The upper level ridge shifts east for the new work week with broad
troughing, northwest flow taking over. Colder, more seasonable air
returns with the change in pattern - no significant cold on the
horizon, but it will feel more like early February.
For pcpn chances, the start of the work week continues to suggest
chances for the southern half of the forecast area. Bits of upper
level energy kick out of the mean trough lifting out of the desert
southwest, with those shortwaves then riding along a southwest-
northeast running sfc front hanging out south of the forecast area.
Decent sloped frontogenetic lift north of the sfc boundary though
while the trough lifts across IA/WI Wed. GFS bufkit soundings point
to good thermodynamic lift through fairly deep low level saturation,
potentially devoid of ice. Favorable setup for drizzle/freezing
drizzle...if this scenario plays out as suggested. The saturation
deepens enough to swing pcpn type over to snow by Tue when
frontogenetic forcing looks strongest. Some accumulations would be
possible.
Won`t get overly refined with pcpn chances and types at this time as
models have enough differences in timing/placement to keep
confidence on the lower end for the details. As it sits, higher
chances locally still hold across northeast IA and southwest WI.
The northwest flow will likely spit a few more shortwaves
across/near the region through the rest of the week, with most light
pcpn (snow) chances. Will let model blend dictate those chances for
now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 551 PM CST Fri Jan 31 2020
While main batch of snow is departing east, another developing
band of snow is poised to move into southeast MN this evening.
This may impact both RST and LSE, depending on how much more it
intensifies over the next hour or so. Forecast soundings would
also suggest potential for patchy freezing drizzle this evening,
but probability is low so did not include in the TAF. Otherwise
ceilings will decline again this evening, likely becoming IFR at
LSE and perhaps LIFR at RST. Also some lingering reduced
visibilitydue to BR. Visibility expected to improve after 06Z,
though trapped low level moisture will keep low ceilings around
through Saturday morning. Models are in decent agreement
suggesting upstream ridging aloft may eventually scour out the low
stratus heading into the afternoon. Have trended TAFs that
direction, but confidence is low given this stubborn pattern in
place. Winds will generally remain 10 knots or less through the
period out of the south to southwest.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION...Kurz
Area Forecast Discussion
National Weather Service State College PA
1025 PM EST Fri Jan 31 2020
.SYNOPSIS...
A fast moving and compact upper level disturbance passing
overhead will bring a few to several hour period of light snow
this evening into early Saturday morning, mainly across the
Northern and Western Mountains of PA.
Temperatures will remain above normal and trend even milder
into the first week of February. Widespread 50s are expected Mon
and Tues along with a fairly widespread rainfall over the area
from late Tuesday morning through early Thursday as a wave of
low pressure moves northeast from the Lower Ohio River Valley to
the Lower Great Lakes.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
630 PM EST update:
Pesky/robust meso-scale upper level speed max moving quickly NE
across the Scent Mtns and Susq Valley of PA early this evening
was responsible for 2 areas of weak uvvel and associated sfc
troughs - one over the western part of the Alleghenies and the
second boundary over Eastern PA.
Raised POPs dramatically over the far SE for just a 1-2 hour
period early this evening as a weak area of 850-700 mb FGEN
scoots by quickly and produces a brief period of light rain with
just a few hundredths of an inch of QPF south and east of KMDT
across York and Lancaster Counties.
The western light rain/snow shield, just about the begin over
the RT 219 corridor, is on track with the results of earlier
high res model and EFS runs.
Previous Disc... Widespread bkn-ovc skies continue to blanket
the entire CWA this afternoon in the form of high-based stratocu
(Western Mtns) and low-end altocu for much of the rest of the
CWA. Virga was quite widespread across the western third of the
state...near and to the west of Route 219, with some light rain
beginning to fall across the greater Pittsburgh Area.
Latest runs of the RAP, HRRR and HREF all target the period
from shortly after dusk through about midnight for some light
QPF across the Western third to half of the CWA. Precip type
will vary with elevation and latitude, with the Laurels most
likely to see a light mix of rain/snow and the valleys of SW PA
most inclined to have more light rain than light snow as Wet
Bulb temps at 0.5KM AGL sneak to around +1C. Wet Bulbs at this
same level stay at -1 to -2C north of the I-80 corridor, so
precip type in the form of light snow is more certain there.
QPF amounts of several to perhaps over 0.10 of an inch in a few
spots suggest there could be between 0.5 and 1.0 inch at 8-10:1
snow water ratios across elevations AOA 2000 ft MSL.
NAM, RAP, HRRR and HREF are suggesting just overcast but dry
conditions across much of our Central and SE zones overnight,
while up to several members of the SREF created some light QPF
even over the Lower Susq Valley. Will still maintain slight chc
or less POPs across the SE third or so of the CWA.
There`s the potential for a bit of clearing toward daybreak
across the far NW zones, that could allow temps to dip into the
low-mid 20s, while the widespread cloud cover elsewhere will
limit temps from slipping below the upper 20s to around 30F.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Little to no airmass change between Fri and Saturday as a weak
inverted trough dissolves over the region in the morning,
followed by a weak sfc ridge for the rest of the day.
Bkn-ovc skies will remain for much of Saturday with variation in
cloud bases mainly between 2-5 kft AGL.
Diurnal change Fri night to Sat will still only be about a
10-12F fall and rise.
Max temps Saturday will be similar to or perhaps a few deg F
higher than Friday - and still 5-8F above normal for the first
day of Feb.
A few flurries/light snow showers possible early Sunday over
the higher terrain, given lingering NW flow and low-level
moisture. General improvement throughout the day, as surface
ridging builds in. Afternoon highs will range from the mid 30s-
mid 40s.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
1030 pm update... A broad SW flow aloft will prevail across much
of the eastern U.S. next week, between a slowly progressive
upper trough axis in the middle of the country and an upper
ridge axis over the southeastern states. This will keep our
weather unsettled, as fairly deep moisture gets transported
towards central PA, along with frequent upper-level
disturbances. Thus, there is high confidence in persistent
light-moderate precipitation for most of the week.
The trickier/less confident part of the forecast involves the
low-level temperature structure across the Commonwealth,
especially from Tuesday night onward. Early in the week
(late Monday-Tuesday), readings would seem mild enough for all
rain. For Wednesday-Thursday, it appears that colder air in the
boundary layer will try to seep into northern PA with time,
perhaps introducing the threat of snow and/or a wintry mix. It
still appears that farther south (south of I-80), the most
probable scenario is for rain to continue.
By the end of the week, colder air should more bodily move
across the Commonwealth, with steadier precipitation
transitioning to mostly snow showers and flurries.
Previous discussion... A digging trough over the western U.S.
will push warmer air our way with temperatures some 15F above
normal through a decent portion of next week. But an elongated
front will approach from the west Mon spreading thickening
clouds across the region. The front will stall overhead through
midweek as a couple of waves slide along it, the first weak one
brings chance for light precip Tue to mainly the NW half, and
after a short break warm/moist flow ahead of the second wave
arrives later Tue night into Wed. These systems will be
primarily rain, though snow could mix in at times over the north
esp at night. A short period of wintry mix is possible across
the north Tuesday morning depending how fast the precipitation
moves in and if temps can slip below freezing.
Unsettled weather then persists through the remainder of the week as
the gradually deepening low pressure system slowly lifts toward an
upper trough sliding across southern Canada.
As the trough over the Central U.S. begins to shift eastward,
another wave develops into yet another blossoming low pressure
system by Thu night/Fri and rides along the same lingering frontal
boundary that will be slowly edging eastward. Precipitation with
this system also appears (somewhat amazingly) to be mostly rain over
the southern half with a primarily rain mixing with snow combo over
the north. Some colder air will work in behind this system, likely
ending precip as a period of light snow for the north and west on
Friday as temps fall back toward seasonal normals.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
A brief period of MVFR cigs (and less likely vsbys) is expected
through 01-02Z for the York Lancaster areas as a weak
disturbance at mid levels of the atmosphere quickly slides en
route to the New England states later tonight.
Expecting VFR conditions for the Central PA airfields KAOO, KUNV
and KIPT until they gradually decrease to MVFR at KJST and KBFD
late this afternoon/early this evening.
Further lowering ceilings in an area of light snow and afterward
across the Western Mtns may lead to occasional IFR cigs and MVFR
to IFR vsbys beginning this evening and lasting for most or all
of tonight.
Elsewhere, ceilings will lower as well today with VFR trending
to MVFR during the evening hours. The exception will be KMDT
and KLNS where VFR is expected to continue until possibly well
after midnight, when some MVFR cigs could develop/advect in from
the west.
.Outlook...
Sat...IFR wrn 1/3 early. MVFR to low VFR cigs elsewhere.
Sun...Restrictions possible at KBFD and KJST in snow showers.
Mon...VFR.
Tue through early Thursday...Restrictions possible with periods
of rain and very low cigs intersecting the ridges at times.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert
LONG TERM...Jurewicz/RXR
AVIATION...Lambert
Area Forecast Discussion
National Weather Service Green Bay WI
558 PM CST Fri Jan 31 2020
Updated aviation portion for 00Z TAF issuance
.SYNOPSIS...
Issued at 211 PM CST Fri Jan 31 2020
Quiet and unseasonably mild through the weekend, then
temperatures returning closer to seasonal normals next week.
The upper flow across North America will briefly consolidate into
a strong zonal band of westerlies across southern Canada and the
northern CONUS during the weekend, then separate back into a
split regime next week. The southern branch of the split will
dominate, with a trough position slowly advancing from the
Desert Southwest to the Lower Mississippi Valley throughout the
week.
Temperatures will remain above normal into early next week,
peaking Sunday as deep strong westerly flow drives downslope-
warmed air across the Midwest. Readings will trend downward after
that, settling close to seasonal normals for the middle to latter
part of the work week. Precipitation will be limited, with just
some scattered light amounts at times. The result will be well
below normal amounts for the period.
&&
.SHORT TERM...Tonight and Saturday
Issued at 211 PM CST Fri Jan 31 2020
The latest RAP analysis and satellite/radar imagery show compact
shortwave energy spinning over the northern Mississippi Valley
early this afternoon. Scattered snow showers are occurring ahead
of this shortwave, over southeast Minnesota and far western
Wisconsin. A low level trough is hanging west of this upper level
feature a bit. But low level southwest winds and weak warm/moist
advection ahead of the trough is contributing to another day of
low overcast conditions across the region. Looking further west,
clearing of the low stratus deck is occurring over the Dakotas,
where downsloping air is pushing in a drier airmass. Forecast
concerns include light precip chances tonight and clearing
potential on Saturday.
Tonight...The shortwave over Minnesota will be diving southeast
and moving over southern Wisconsin. With decent mid-level lapse
rates, it is possible that moisture could become deep enough for
light snow showers and/or freezing drizzle for a time this evening
into early overnight over central WI and the Fox Valley. Don`t
think widespread hazardous travel will develop with this feature,
but not unrealistic to think a few slippery stretches are
possible, particularly over central WI. Unsure if freezing
drizzle or flurries could occur further north, as there has been
little to any returns on radar or on observations upstream. Will
include a chance of flurries, though no impacts are expected.
Because of the cloud cover, temps will likely only far a few
degrees.
Saturday...A low overcast with some mist or haze will likely
remain present across the region in the morning. But as strong jet
energy arrives, winds will veer around to the west and are
projected to bring in drier air. This could bring in clearing for
a time, perhaps as early as late morning over north-central WI,
though think afternoon is a better bet with help from daytime
heating. Mid and high clouds are expected to move overhead
thereafter, so any clearing will likely be relatively brief. Low
level temps will be warming, so temps in the low to middle 30s
look about right.
.LONG TERM...Saturday Night Through Friday
Issued at 211 PM CST Fri Jan 31 2020
The most significant element of the long-term forecast will be the
mild weather expected Sunday. Determining exact high temperatures
in a situation such as this is a challenge, but believe the
tendency will be for guidance to underestimate the amount of
warming that can occur with the blustery west winds despite the
widespread snowcover. So edged maxes up a bit toward the MEX/ECX
values, which puts them 16-20F degrees above normal, and close to
the records for February 2.
There could be some light precipitation (snow or freezing
drizzle) Saturday night, especially across the northeast portion
of the forecast area in a region of weak isentropic lift at the
leading edge of the warmer air. Otherwise, low-end PoPs were
common in the extended portion of the forecast as the forecast
area will be susceptible to scattered light precipitation as
disturbances rotate through the longwave trough slowly progressing
east across the CONUS.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 547 PM CST Fri Jan 31 2020
A couple upper level disturbances will affect the forecast area
during the TAF period. The first will brush through central and
east central WI this evening, and the second will impact most of
the region late tonight into early Saturday. Moisture will be
limited, and mainly confined to low-levels, so intermittent
flurries and freezing drizzle will be the main concern. Flight
conditions should remain in the MVFR category, with brief periods
of IFR conditions, through early Saturday morning.
Increasing southwest to west winds will bring in a drier low
level airmass into the region on Saturday. This will cause
ceilings to gradually rise in the morning, followed by partial
clearing and possible VFR conditions during the afternoon.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....MPC
LONG TERM......Skowronski
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Grand Rapids MI
731 PM EST Fri Jan 31 2020
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 311 PM EST Fri Jan 31 2020
- Some light snow later tonight into Saturday morning. A few
slick spots.
- Mild and Breezy Sunday
- Possible winter impacts Monday night into Thursday
&&
.UPDATE...
Issued at 731 PM EST Fri Jan 31 2020
This update goes along very nicely with the 311 pm discussion.
However our grids did not have likely pops for Saturday morning.
As stated below we have deep lift in a moist layer due to the
approaching warm front tomorrow morning. Every member of the 50
member ECMWF ensemble has measurable precipitation at both MKG
and GRR Saturday morning and all of them also have measurable snow
(using 10:1 ratio). Also the WPC super ensemble vier have every
member of the HI res ensembles giving SW MI measurable
precipitation. Given that, and looking at the latest runs of the
HRRR, NAM3km, RAP models, and looking at both the IR satellite and
radar loops over the midwest and western Great Lakes, it seem to
me it will SNOW here tomorrow morning. Mind you,this will be a
trivial snowfall event, most locations getting less than a half
inch but none the less it will snow. Once again this totally goes
along with our previous forecasters discussion. So, I updated our
forecast and grids to say that.
&&
.DISCUSSION...(This evening through next Friday)
Issued at 311 PM EST Fri Jan 31 2020
- Some light snow later tonight into Saturday morning. A few
slick spots.
A weak wave of low pressure moves in from the west later tonight
and pushes east of the area by Saturday Afternoon. The DGZ
moistens up then as weak upward vertical arrives. Thus a window
for light snow exists later tonight into Saturday morning across
the CWA. The region along and to the northwest of a Holland to Mt
Pleasant line will see the deepest saturation so we will feature
the highest POPs there. Less than an inch of snow is forecasted.
Limited impacts look possible in the morning with daytime
temperatures starting out near or just below freezing. The
temperature is forecasted to slowly rise above freezing in the
morning. The DGZ becomes unsaturated for the afternoon so any
remaining precipitation should wind down quickly then.
- Mild and Breezy Sunday
There is a signal in the models that shows deeper drying in the
atmosphere on Sunday...with even the low level moisture
diminishing. So it is looking like we will see some sun. An 925 mb
thermal ridge arrives so Sunday is looking like a relatively mild
day. However with the flow from Lake MI and relatively stronger
winds located not too far off the ground it may not feel that
mild. Wind gusts may top 30 mph.
- Possible winter impacts Monday night into the end of the week
A slow moving positively tilted mid level trough approaches from
the west Monday night and does not track through until at least
Thursday. Several rounds of precipitation are possible. Enough
cold air will be in place for some of it to be snow. Which could
lead to impacts. Gulf moisture arrives ahead of the trough which
will provide the moisture needed for the precipitation. Models are
in relative agreement on this scenario.
One mid level shortwave rides up the OH Valley Monday night into
Tuesday with the right entrance region of an upper jet over MI.
So we will feature a risk for snow which could mix with rain
across the south. The frontal zone remains over the area Wednesday
into Thursday as another jet streak and mid level wave arrive.
This could support another round of precipitation. It will be
colder then so mainly snow would be the primary precipitation
type. Thus a risk for slick travel conditions exists.
A period of lake effect snow showers is possible Thursday into
Friday as some arctic air advects in from the northwest.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 708 PM EST Fri Jan 31 2020
For most of our TAF sites I expect VFR or MVFR (just into MVFR
like 2500 ft agl) cigs through at least 08z or so.
MKG on the other hand is in a place where the prevailing SW winds
will continue to generate lower clouds and some light snow
showers, seem MVFR will prevail there most of the night.
On Saturday the warm front from that system to the north gets
close enough to generate deep lift during the mid to late morning
hours. This will result in several hours of IFR conditions at
most of the TAF sites with snow being the primary cause.
Once the deep lift ends the mid clouds move out (in the 18z to 21z
time frame). This will end the snow but we may see a period of
drizzle and low clouds. I was sort of optimistic in our TAF
forecasts with that showing IFR/ low MVFR conditions late
afternoon but if the drizzle develops (it should be to warm for
freezing drizzle) we could see solid IFR like 1SM -DZ BR OVC003.
Just be aware this could happen. It will be a little breezy
tomorrow too.
In clouds, Saturday, while it is snowing,icing should be moderate
mixed icing in the 2000 ft to 10000 ft layer. After the snow ends
expect mostly light mixed icing in the 2000 ft to 4000 ft layer.
&&
.MARINE...
Issued at 311 PM EST Fri Jan 31 2020
The pressure gradient tightens up later tonight and more so on
Saturday as the next wave of low pressure moves in. Southwest
winds will strengthen as a result...building the
waves...especially north of Muskegon. Conditions will likely
become hazardous for small craft. The wind shifts of the west on
Sunday as the winds and waves slowly diminish. Hazardous
conditions will likely linger for a while during the day.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory from 7 AM Saturday to 4 AM EST Monday for
LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...MJS
DISCUSSION...MJS
AVIATION...WDM
MARINE...MJS