Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/31/20
Area Forecast Discussion
National Weather Service Boston/Norton MA
1009 PM EST Thu Jan 30 2020
.SYNOPSIS...
High pressure passes over our area tonight, then moves offshore
during Friday. Temperatures moderate on Friday with dry
conditions expected. Developing low pressure tracks well
offshore Saturday. This system may bring light amounts of rain
or snow to the region, with the best chance along the south
coasts of Massachusetts and Rhode Island. Cool, blustery and
mainly dry weather follows Sunday behind the departing ocean
storm. High pressure off the southeast U.S coast provides dry
mild weather Monday. An approaching cold front may bring a risk
of showers and mild temperatures by Wednesday. Colder air and a
mix of rain and snow showers will be in place for Thursday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
10 PM Update...
Increased cloud cover across southern New England to account for
the cirrus clouds moving through per observations. Have also
bumped up low temperatures a few degrees to account for more
cloud cover. Still monitoring the cloud cover across central PA
and western NY. Have held off in bringing this in per the latest
RAP guidance, but will need to keep an eye on it for Friday.
7 PM Update...
High clouds will move over Southern New England during the
night. Satellite imagery shows lower clouds now moving into
Central PA, at a pace that would bring them into Southern New
England starting around 7 AM. This will be monitored and may
eventually lead to a cloudier forecast for Friday. But as for
the overnight period the observations are in line with the
forecast. No significant changes with this part of the forecast.
Previous discussion...
High pressure is centered over Southern New England, and slides
offshore toward morning. A short wave moving over the region
brings scattered high deck clouds, but mainly clear skies are
expected for most of the night. The clouds may temper overnight
lows somewhat. Thinking we will get close to lows from Thu
morning, just a couple of degrees or so warmer. Thus forecast
lows are in the teens and low 20s, except along the immediate
shorelines of MA and RI, as well as the Cape and Islands, with
lows in the 20s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Friday...
Surface high moves further offshore while mid level ridging builds
in for much of the day. Expecting mostly sunny skies for the
morning, then during the afternoon increasing clouds from SW to NE
as the ridge moves offshore and moisture increases. This is mainly
mid and high level moisture. One caveat to watch during Friday is
the southwest flow may result in a marine layer/low level moisture
pooling under the inversion. Thus there is a chance for marine
stratus tomorrow in southern RI east to the Cape and Islands.
Otherwise a dry day with moderating temperatures. Highs in the upper
30s to low 40s across much of the region, some mid 40s are possible.
Friday night...
Increasing clouds during the evening as southern stream low pressure
system emerges off the Carolina coastline. While mainly dry
conditions are forecast, there is the potential for some light snow
or light rain during the overnight. Have low chance pops for HFD-PVD
and SE MA, with a dusting to a couple tenths of an inch of snowfall
is possible. To the north have opted for slight chance pops with a
dusting of snow possible. Overnight lows in the upper 20s to low 30s
for most of the area.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Big Picture...
Northern and southern streams connect and disconnect during the
period. Major features are a phased trough moving through the
Eastern Seaboard over the weekend, then a Pacific NW trough digging
over the West and then shifting east to the Plains midweek.
Model upper contour fields show a period of cooling over the
weekend but are otherwise milder than normal.
Mass fields are in agreement through Monday, and show a general
similarity even through next Thursday. Confidence is good through
the time period.
Daily Concerns...
Saturday-Sunday...
Upper trough sweeps east across the Eastern Seaboard with a firmly
progressive axis. A 170-kt jet from the southern stream moves
through the trough and generates a coastal low in the Eastern Gulf
and Carolina coast. The progressive flow carries both features
northeast on a path that remains outside the 40/70 benchmark. This
keeps most of the storm`s lift offshore of Southern New England as
it passes. This suggests most of the precipitation will be offshore
with values light at most over land. The best chance will be
south of the the MA Pike. Temperatures project an initial rain
along the coast and a snow/rain mix inland. This changes to all
rain by the afternoon. Precip Saturday tapers off Sunday morning.
The upper trough moves overhead Sunday morning-midday and should
maintain clouds through that time followed by drying in the
afternoon.
Temperatures in the mixed layer will be equiv to -8C to -10C,
which suggests max sfc temps in the upper 30s and lower 40s.
Sunday night through Thursday...
Warm front lifts through New York and New England Sunday night
bringing a period of clouds and showers, with the best chance of
showers over northwest Mass. Strong west winds are indicated Sunday
night and Monday with low level values reaching 30 kt and 850 mb
values at 40-50 kt.
Weather system passes north of New England Tuesday and slowly pulls
a cold front south over Southern New England midweek. This will mean
a period of showers during that time, with mild temperatures
Tuesday/Wednesday. As winds shift out of the northwest
Wednesday night, the air will cool sufficiently to change the
rain to snow from northwest to southeast. Temperatures will be
borderline Thursday, so look for rain showers southeast and snow
showers northwest.
Mixable temps aloft will be equiv to -8 to -10C aloft Sunday,
then -4C to -6C Monday through Wednesday. Cooler air moves in
Thursday, with equiv temps aloft at -9C to -12C. All of this
translates to max sfc temps in the upper 30s and lower 40s
Sunday, then upper 40s/lower 50s Monday through Wednesday, and
mid 30s to lower 40s Thursday.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...
VFR with light and variable/calm winds becoming light SW.
Satellite and observations show lower clouds over Central PA
edging east, with cloud bases at 3500-4000 feet. These clouds
are moving at a pace that would bring them to the CT Valley at
or after 7 AM.
Friday...
Mainly VFR with SW winds 5-10 kt. There is a slight
chance of BKN MVFR CIGs along south coastal MA/RI with the
possibility of marine stratus.
Friday night...
VFR to MVFR CIGs developing, with light SW winds. Low
chance/slight chance for light snow/rain. VSBYs could be reduced
below 5 miles in SE MA/Cape/Islands and RI.
KBOS Terminal...High confidence in TAF. Slight chance of a sea
breeze during Fri afternoon.
KBDL Terminal...High confidence in TAF.
Outlook /Saturday through Tuesday/...
Saturday: Mainly MVFR, with local IFR possible. Breezy. Slight
chance RA, slight chance SN.
Saturday Night: Mainly IFR, with local MVFR possible. Breezy.
Slight chance SN.
Sunday: Mainly VFR, with local IFR possible.
Sunday Night: Mainly VFR, with local IFR possible. Breezy.
Monday through Monday Night: VFR. Breezy.
Tuesday: MVFR/IFR conditions possible. Slight chance SHRA,
slight chance FZRA.
&&
.MARINE...
Tonight...
Variable winds becoming light from the SW overnight as high
pressure passes over the area. Seas on the outer waters 2 to 4
feet, diminishing to 1-2 feet.
Friday...
Tranquil day on the waters as high pressure gradually moves east of
the waters. SW winds increasing to 10 to 15 kts, with seas 1 to
3 feet.
Friday night...
Remaining in between systems as a low pressure emerges of the coast
of the Carolinas. SW winds 10 to 15 kts continue, with seas 1 to 3
feet.
Outlook /Saturday through Tuesday/...
Saturday: Winds less than 25 kt. Chance of rain.
Saturday Night: Winds less than 25 kt. Local rough seas. Slight
chance of rain, slight chance of snow. Local visibility 1 to
3 nm.
Sunday: Winds less than 25 kt. Local rough seas.
Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas.
Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Local rough seas.
Monday Night: Winds less than 25 kt. Seas locally approaching
5 ft.
Tuesday: Winds less than 25 kt.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...WTB/NMB
NEAR TERM...WTB/BL
SHORT TERM...NMB
LONG TERM...WTB
AVIATION...WTB/BL
MARINE...WTB/BL
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
633 PM CST Thu Jan 30 2020
...Aviation Update...
.SHORT TERM...(This evening through Friday)
Issued at 330 PM CST Thu Jan 30 2020
Satellite imagery shows stratus continuing to slowly erode from
west to east across the area. Areas west of Highway 281 will end
up seeing a nice bit of sunshine late this afternoon, but those
closer to Highway 81 will likely see stratus linger straight into
the evening and overnight.
Tonight, a quick-moving shortwave and associated cold front will
move from northwest to southeast across the area. A mix of light
rain or snow is possible as this moves through, but most of the
local area will only see sprinkles/flurries.
Stratus will also expand westward again tonight, but fog isn`t
expected to impact as much of the area as the previous couple
nights. This is largely due the increasing northwest wind behind
the cold front. That being said, the HRRR and RAP show some
reduced visibility, mainly over northeastern portions of the area.
On Friday, some sprinkles/flurries may linger into the morning,
but should come to an end between 15-18Z as the upper level trough
axis moves through. Temperatures are expected to range from the
mid 30s in the east to the mid 40s in western portions of the area
that will see more sun. This is pretty similar to today`s
temperatures, but northwest wind gusts to around 25 MPH will make
it feel a bit chillier.
.LONG TERM...(Saturday through Thursday)
Issued at 330 PM CST Thu Jan 30 2020
We will kick off February with a very warm weekend thanks to
broad ridging at the mid and upper levels. On Saturday, westerly,
downsloping winds should push highs into the 50s and 60s...a solid
20 degrees above our climatological normals.
Sunday should be even warmer than Saturday. 850mb temperatures
are forecast to be in the 17-19C range, likely translating to
surface temperatures in the 60s for most. In fact, the EPS mean is
in the 60-65 degree range for the entire area. The one issue is
that the GFS continues to be faster with the next front, which
leads to noticably cooler temperatures in northern portions of the
area. Because of this uncertainty, our current forecast keeps
some mid 50s in our north and east, but this could very well end
up being too conservative. Long story short, it is going to be an
unseasonably mild day, so get outside and enjoy it!
The pattern flips back to cold on Monday as an advancing upper
level trough pushes a cold front through the area. Highs on Monday
may struggle to reach freezing...easily 20-25 degrees colder than
Sunday.
Both the GFS ands Euro then show this aforementioned trough
become more positively tilted and slide through the area Monday
night into Tuesday. This doesn`t look like a significant winter
storm, but a few inches of snow are possible in portions of the
area. Obviously, there is still plenty of uncertainty on amounts
and location, so make sure to check back over the weekend or early
next week.
It will remain relatively cold through the middle of next week,
but we may see a bit of a "warmup" back into the low 40s late in
the week into the following weekend. Of course this will depend on
the presence/lack of any snow cover. Beyond that, it appears that
we will see a colder-than-normal pattern persist through at least
the middle of February.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 631 PM CST Thu Jan 30 2020
General overview:
Yet another fairly complex/low-moderate confidence TAF, especially
with regard to ceiling height. From a very general perspective, we
anticipate both KGRI/KEAR to spend the majority of the period
under an MVFR ceiling, although at least starting out this evening
KGRI is currently IFR and KEAR is VFR, so there is quite a
disparity between these two (relatively) nearby terminals.
Visibility-wise, KEAR should remain VFR throughout, but KGRI could
see at least occasional MVFR these first several hours. Winds are
actually fairly straightforward/similar for both sites, with
initially southerly breezes this evening soon turning westerly and
eventually more northwesterly behind a passing cold front. In
fact, the majority of the period will feature WNW breezes
sustained 10-15KT with some slightly higher gusts possible.
Precipitation-wise, while nothing measurable is expected, both sites
(but probably slightly favoring KGRI versus KEAR) could see
passing sprinkles/flurries at almost any point through late Friday
morning. Read on for a few more ceiling-related details if
interested...
Ceiling details (low-moderate confidence):
As mentioned above, right out of the gate this evening we have
quite a disparity between KGRI (IFR) and KEAR (VFR). While
confidence in exact timing leaves a lot to be desired, the general
expectation is that both sites will trend toward a middle-ground
of MVFR later this evening/overnight, as ceilings rise a bit at
KGRI and an MVFR deck eventually arrives/settles in from the
north-northwest into KEAR. That being said, especially at KEAR,
this lower cloud deck could also end up prevailing as low-end VFR
instead of MVFR, it`s just a tough call at this point. About the
only thing that currently carries halfway-decent confidence is
that both sites should become prevailing VFR by sometime Friday
afternoon.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Hanford CA
426 PM PST Thu Jan 30 2020
.UPDATE...Updated air quality issues section.
&&
.SYNOPSIS...
Eastern Pacific ridging pattern continues for the next few days
keeping the forecast dry and warmer than average. A disturbance is
forecast to bring light precip to the forecast area on Sunday,
before another period of dry weather next week.
&&
.DISCUSSION...
GOES-17 visible satellite imagery shows high clouds moving
southward across the forecast with a ridge of high pressure off to
our west. As high pressure influences our weather today,
afternoon highs will be several degrees warmer than yesterday,
with afternoon highs in the 60-63 degree range across the San
Joaquin Valley. 18z HRRR run is not showing much in the way of
fog, but areas that get some clearing overnight could see some
localized fog tomorrow morning. Heading into tomorrow, 500 mb
heights continue to rise over Central California. Warming trend
will continue tomorrow as a result, and highs are expected to be
in the mid 60s across the valley, and near 70 in the Mojave
Desert. As the ridge nudges east Friday night into Saturday
morning, skies could be mostly clear, which may lead to fog
formation across the valley.
The dry pattern continues on Saturday, and depending on how much
cloud cover there is during peak heating, it could be the warmest
day of the week. The pattern changes on Sunday when an Inside
Slider trough impacts the forecast area. Blended model guidance is
forecasting light precip totals in the mountainous areas of the
forecast area with this system through Monday morning.
Accompanying the trough will be tightening gradients, leading to
gusty winds across the Kern County Mountain passes and desert.
A cooler airmass will be in place for the early portion of next
week, with the main impact likely being the chilly morning lows on
Tuesday and Wednesday morning. By midweek next week, another EPAC
ridging pattern is being forecast by most global models,
continuing the dry weather pattern.
&&
.AVIATION...
IFR and local LIFR visibility and ceilings in mist and fog
10z through 17z Friday in the San Joaquin Valley. Otherwise, VFR
conditions will prevail for the next 24 hours.
&&
.AIR QUALITY ISSUES...
On Friday January 31 2020... Fireplace/Wood Stove Burning Status
is: No Burning Unless Registered in Fresno... Kern... Kings...
Madera and Tulare Counties.
Further information is available at Valleyair.org
&&
.CERTAINTY...
The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is medium.
Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.html for additional information
an/or to provide feedback.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
public/aviation/fw...Bollenbacher
PIO/IDSS.............DH
weather.gov/hanford
Area Forecast Discussion
National Weather Service Lincoln IL
843 PM CST Thu Jan 30 2020
.SYNOPSIS...
Issued at 209 PM CST Thu Jan 30 2020
Cloudy conditions will persist across the region to close out the
week. There is a chance of light snow tonight, particularly south
of a Jacksonville to Bloomington line. Accumulations will be very
light, only a dusting in some locations. Temperatures will fall
into the mid 20s to lower 30s across central Illinois. On Friday,
temperatures will warm into the upper 30s to lower 40s.
&&
.UPDATE...
Issued at 843 PM CST Thu Jan 30 2020
Short-wave trough currently over eastern Kansas will eventually
tap into limited deep-layer moisture to bring a period of light
precip to central/southeast Illinois overnight into Friday
morning. Upstream radar imagery and surface observations show
light snow developing across western/southern Missouri. This
precip will spread northeastward into the KILX CWA mainly after
midnight, with the most widespread precip confined to locations
along/south of I-70. Latest HRRR suggests it will be slow to
arrive and may not fully develop until closer to dawn. Precip type
will initially be a drizzle/flurry mix, but will quickly change to
light snow as the seeder-feeder mechanism provides ice crystals to
the low-level moist layer. Overnight snow amounts will be quite
light...amounting to only a couple tenths of an inch at most.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 209 PM CST Thu Jan 30 2020
Surface ridge of high pressure over the Midwest this afternoon
will drift east towards the East Coast tonight allowing
southwest flow to spread back across the Mississippi Valley. The
combination of modest low/mid level warm air advection and
falling heights from approaching upper low digging across the
Upper Midwest will result in modest synoptic scale ascent across
the region this evening and overnight. Low level moisture remains
locked in place across the region, and deeper moisture is progged
to arrive as southwest flow returns. This should allow for some
precip in at least portions of central Illinois overnight. May
initially see drizzle or patchy freezing drizzle near the onset of
precip this evening before the deeper moisture allows for ice
nuclei to be introduced into the column resulting in snow. While
there remains some uncertainty in how widespread snow will be
overnight, some very light accumulations of a dusting to a few
tenths are possible by daybreak Friday, particularly south of a
Jacksonville to Bloomington line.
A lead shortwave trough ejecting from the base of the main upper
trough will shift east of the local area early on Friday and
should provide a window of subsidence and dry weather through the
day Friday. Temperatures will warm into the upper 30s to lower
40s under continued cloud cover. The main upper trough is then
progged to move across the region Friday evening and overnight
with the chance for light precip returning, primarily snow,
particularly along and north of the I- 72/Danville corridor.
Coming off relatively mild daytime temps and maintaining surface
temps near freezing Friday night, and overall light intensity
expected, the chance for accumulating snow seems fairly low,
perhaps a dusting on grassy surfaces.
.LONG TERM...(Friday night through Thursday)
ISSUED AT 209 PM CST Thu Jan 30 2020
Upper low will pass east of the region early on Saturday with
strong subsidence overspreading central Illinois in its wake.
This will shut down precip chances through the weekend, though
cloud cover will likely remain trapped under a strong inversion on
Saturday. By Sunday though, continued subsidence should help
erode stratus from above as the inversion heights lower, while
mixing in the boundary layer with increasing southwest winds
should help scour out remaining low level moisture. Outside of
some passing high clouds then, this should set the stage for the
return of sunshine to the area. Very warm temps aloft of 15-16C at
900mb are progged to overspread the local area resulting a very
steep inversion. Temperatures will be a bit tricky as a result as
very modest changes in the depth of the mixing will result in
several degrees difference at the surface. IF (and only IF) clouds
clear as expected, we should easily be looking at a top 5-10
warmest day on record if not near record highs for February 2nd.
The uncertainty in the cloud forecast adds a considerable bust
factor to temps on Sunday. Guidance ranges between 40s on the cold
end from the NAM to 60s from the ECMWF with majority of models
clustering in the lower to mid 50s.
Meanwhile on Sunday, low pressure will be moving east across
Ontario with a trailing cold front sagging south across the
Upper Midwest and stalling over central Illinois on Monday.
Farther west, a strong trough is progged to dig across the western
CONUS, lifting northeast across the Great Plains on Tuesday. Low
pressure will form over the plains as a result with precip chances
returning along the stalled frontal boundary and ahead of the
approaching upper trough later Monday through the middle of the
week. Expect sharp temperature contrast across the aforementioned
front, possibly around 30 degrees of difference between the
northwest and southeast counties of the forecast area. Placement
of the boundary will be key to temps at any given location, so
don`t be surprised to see changes in the forecast for your area if
the placement of the expected frontal position shifts in the
coming days. Precip chances should end with some snow midweek as
the low departs towards the east coast. Dry but more seasonable
conditions look likely for the latter half of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 538 PM CST Thu Jan 30 2020
Ceilings have risen to VFR at all terminals except KBMI late this
afternoon. While FEW-SCT lower clouds will be present, it appears
VFR conditions will persist for a few hours before gradually
lowering to MVFR by around midnight. As an upper disturbance
approaches from the southwest, all models suggest a further
lowering to IFR at KSPI by 09z...then further northeast to
KBMI/KCMI by around 11z. In addition, areas of fog will develop,
reducing visbys to 2-3 miles late tonight into Friday morning. The
fog will be slow to dissipate, with visby restrictions likely
lingering until early afternoon. Winds will remain light/variable
through the entire 00z TAF period.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barnes
SYNOPSIS...Deubelbeiss
SHORT TERM...Deubelbeiss
LONG TERM...Deubelbeiss
AVIATION...Barnes
Area Forecast Discussion
National Weather Service Northern Indiana
605 PM EST Thu Jan 30 2020
.SYNOPSIS...
Issued at 218 PM EST Thu Jan 30 2020
Dry but cloudy conditions will persist this afternoon. There could
be a few flurries coming off Lake Michigan this evening. There is
a chance for snow Friday morning but little to no accumulation is
expected. Another chance for rain or snow will arrive Saturday
morning but dry, sunny, and warm conditions are anticipated for
Sunday. A more significant weather system is possible middle of
next week.
&&
.SHORT TERM...(This Evening through Friday)
Issued at 218 PM EST Thu Jan 30 2020
Upper ridging and surface high pressure across the area this
afternoon have allowed for mostly dry conditions. However, there
does continue to be some low-level moisture trapped under the
inversion, which is responsible for the persistent cloud cover.
Added a slight chance of snow showers along Lake Michigan and to the
southwest for late this afternoon and evening in coordination with
NWS LOT. The HRRR is showing some lake-enhanced convergence in
conjunction with a weak mid-level shortwave, but confidence is
low given drier air at the surface and aloft. Moisture is expected
to increase overnight though as a trough moves in from the west.
This will bring a decent chance of snow through Friday morning
across the area, but accumulations will be light at less than an
inch. Decent b boundary layer mixing can also be expected with
this system, which will allow afternoon temperatures to rise into
the mid to upper 30s, thus melting most of any snow that does
accumulate.
&&
.LONG TERM...(Friday Night through Thursday)
Issued at 218 PM EST Thu Jan 30 2020
A somewhat stronger shortwave will move into the region by Saturday
morning, with another chance of a wintry mix and snow, but
accumulations will again be minimal. Latest model runs have cut back
on QPF with better energy both north and south in a slightly split
synoptic scale flow pattern. Dry high pressure will then build over
the center of the country on Sunday and temperatures will warm well
above normal, with highs both Sunday and Monday around 50 degrees.
Rain is expected to begin Monday night in association with a warm
front. The cold front will move south of the area Tuesday, and
temperatures will cool some, but precipitation should remain
mostly rain through the day. Much colder air will advect in on
Tuesday night and Wednesday, thus the rain will change to snow. At
this time it is too soon to give specific accumulation amounts
due to storm track uncertainties, but several inches of snow may
be possible. Drier conditions should follow for Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 605 PM EST Thu Jan 30 2020
Persistent overcast will continue through this TAF cycle.
Ceilings to begin at low end VFR this evening then drop down to
MVFR Friday morning as weak system moves through the region.
Model blend does have brief window of IFR cigs and MVFR
visibilities mid-day Friday but given very weak signal among the
ensemble members for any measurable precip to accompany this
system prefer to stick with MVFR ceilings for now. Winds expected
to remain light and variable through the period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...Cobb
SHORT TERM...Cobb
LONG TERM...Cobb
AVIATION...JAL
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Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
849 PM CST Thu Jan 30 2020
.UPDATE...
849 PM CST
Evening Update...
Have updated forecast to include a mention of flurries and patchy
light freezing drizzle this evening, mainly from the Chicago metro
area west. Not expecting impact from freezing drizzle, given its
patchy/very light nature and expected short duration. Also
increased pops for light snow overnight, mainly in the I-80 to
I-88 corridor regions of northern IL. No changes to minor
accumulations, with generally less than a half inch expected.
After a quiet late afternoon/early evening, regional radar mosaic
is indicating some very light precipitation moving across north
central IL at mid-evening. Surface reports indicate this is a mix
of some very light snow/flurries and some very light freezing
drizzle. DVN`s 00Z sounding indicates the top of the low level
stratus layer is in the -10C range, which should support ice
crystal nucleation and snow flakes, though surface obs indicate
otherwise. Mid-level saturation, seen at/above 600 mb in DVN`s
sounding, is expected to lower overnight however, which is
expected to provide ice crystals/flakes in a seeder-feeder process
which should turn precip over to all light snow in time. IL
doesn`t have much roadway surface temp data available, though
current road temps just west of the Mississippi River in eastern
IA are in the 32-34 range, and with slightly higher air temps
farther east this is likely an indication that any patchy light
freezing drizzle should have little if any road impacts.
Farther to the west, radar returns across parts of central and
southeast IA are what is expected to expand eastward across
northern IL and northwest IN after midnight tonight, and produce a
period of light snow. This is in association with the northeastern
periphery of a short wave tracking across Missouri and central IL.
Weak but persistent warm advection, and isentropic upglide, with a
slight enhancement to modest H8 southwesterly winds, appears to
peak during the midnight-sunrise period. Model guidance continues
to indicate a couple of hundredths of QPF which would translate
to some minor accums of less than half an inch by the time things
taper off to flurries around sunrise Friday morning. 4 km WRF
simulated reflectivity, and to a similar but lesser extent the RAP
and HRRR, appear to focus the I-80 and I-88 corridor regions
across northern IL for perhaps the better accumulation potential,
and have boosted pops across these areas into the likely category.
Forcing weakens shortly after sunrise, though low level stratus
may continue to produce flurries during the day, as broad upper
trough remains across the region above our persistent low level
stratus.
Ratzer
&&
.SHORT TERM...
219 PM CST
Through Friday...
Our stagnant weather pattern continues today, with widespread cloud
cover locked in underneath a stout subsidence inversion above 6 kft.
For the rest of the afternoon, not expecting much change from what
you see outside as a result. Some hints remain in the guidance that
a subtle increase in low-level convergence immediately near the lake
may help to squeeze out a few snow showers late this afternoon and
into the early evening hours, but these look to be of relatively
minimal consequence given the marginal degree of low-level
saturation.
The main feature of interest that we`re monitoring is an upstream
shortwave trough which is pinwheeling eastward across the Northern
Great Plains early this afternoon. Within this broad cyclonic mid-
level flow are several subtle disturbances which will be slowly
translating overhead through at least the next 36 to 48 hours or so.
The first disturbance looks to bring a period of lightly
accumulating snowfall to the region later tonight and into Friday
morning. This wave can be seen in recent moisture-channel imagery
across northwestern Iowa. Recent mesoanalysis reveals a fairly steep
mid-level lapse rate plume is in place out that way, not surprising
given the convective look to recent satellite images. The core of
this steeper lapse rate environment does look to remain mainly south
and west of our region through tonight, but always is a little
worrying to see pockets of 8+ C/km lapse rates lurking nearby.
Overall guidance is in pretty good agreement depicting light
precipitation overspreading most of the region around and just after
midnight as the core of mainly modest forcing for ascent moves in.
Most of this lift can be seen on the 285 K theta surface tonight
with the main area of ever-so-slightly more enhanced upglide
developing near and north of the I-80 corridor. Guidance today has
trended towards perhaps a bit more in the way of QPF for the
overnight/Friday morning period as a result, and have gently nudged
snowfall amounts up just a bit to near a half inch in isolated
spots. There is some potential that at the front end of precip
there`s a brief lack of cloud ice for heterogeneous nucleation
with a lingering dry wedge in the 5-10 kft layer limiting the
potential for seeder-feeder mechanisms to help things out in that
department. Low-level cloud top temperatures do look to remain in
the -9 to -10 C range, so do not have any freezing drizzle
mentioned at this time, but is something we`ll be keeping an eye
on. Either way, as the mid-levels continue to saturate, it does
look like we`d be able to quickly inject additional ice crystals
from above into the lower stratus deck, turning any spotty drizzle
over to light snow. Interestingly, some of the recent hi-res
guidance is spitting out pockets of several hundredths of an inch
of liquid-equivalent QPF through Friday morning, which could
support some isolated snowfall amounts headed towards one inch.
Most of this activity looks to end through the mid-morning hours
on Friday although, as has been case recently, we won`t have any
mechanisms to really scour out the low-level moisture. As a
result, flurries or even some lingering light snow will remain
possible into the afternoon hours, mainly for locales east and
south of I-55 where we`ll likely hold onto a sliver of low-level
instability.
Carlaw
&&
.LONG TERM...
Friday night through Thursday...
200 PM...Forecast concerns remain light snow potential Friday
night...warm-up Sunday/Monday and then a possible winter storm for
Monday night through Tuesday night.
The last of this week`s series of weak waves will move across the
area Friday night and overall...models have weakened some with
this system. There is still a potential for a light dusting of
snow but temperatures will likely be in the lower 30s...so there
may not be much impact. This activity will quickly end from west
to east overnight and Saturday morning is now looking mainly dry.
However...as precip ends there may be one last chance for drizzle
or freezing drizzle where temps remain below freezing.
Models then quickly transition to significant warming Saturday
night into Monday with some bust potential...especially over the
deeper snowpack across the northwest cwa which may mute the
warming some. It does appear that Sunday will see sunshine...
perhaps some higher clouds by afternoon. Assuming sunshine does
occur...high temps Sunday appear in-line with mex/ecm mos
guidance...40s over northwest IL...lower/mid 50s elsewhere.
High temps on Monday have always been tricky based on when a cold
front moves across the area. While this front may not be all that
strong...it will likely mean the difference of several degrees.
The gfs/gem are still showing a shift to northeast across much of
northern IL by Monday morning with the ecmwf now showing a faster
shift to northeast on Monday. Temps likely could still be well
into the 40s with 50s possible across the far south but there
still remains some uncertainty for high temps Monday.
Ecmwf has been overall rather consistent with its solution over
the past few days for the possible storm system Monday night
through Tuesday night next week. Only notable change this
afternoon is precip duration now stretches into Wednesday morning.
The same trend of rain mixing/changing to snow is on track with
the potential for a wintry mix somewhere in the middle. While it
remains too early for details...the general track of the system
has remained similar and would lay out a band of snow of at least
a few inches across mainly the northern half of the cwa. As the
winds turn northeast...they steadily increase Monday night into
Tuesday as the gradient tightens. Still several days away but
this time period would also need to be monitored for possible
lakeshore flood concerns. cms
&&
.CLIMATE...
Here are the record highs Sunday into Monday. Sunday`s record high
temp for Chicago looks to be most vulnerable and is the lowest
record high temp for the month of February.
Sun Feb 2 Mon Feb 3 Mon Feb 3
Record High Record Warm Low Record High
Chicago 51 (1992) 39 (2019) 59 (1992)
Rockford 52 (1987) 37 (2019) 54 (1992)
- Izzi
&&
.HYDROLOGY...
355 AM CST
Much of the Rock River basin is running at greater than 90% of
normal streamflow for late January and the Fox river is running
close to 90% of normal. NOAA`s National Operational Hydrologic
Remote Sensing Center is estimating 1 to 2 inches of water locked
up in the snow pack over north central IL east into the upper Fox
River watershed. If current forecasts for record/near record
warmth verify, then rapid snowmelt would take place Sunday and
especially into Monday as dewpoints potentially rise into the 40s.
At this point, no significant rain is forecast Sunday or Monday,
but with the Rock and Fox Rivers running so high, rapid snowmelt
could result in significant rises on the Kishwaukee, Pecatonica,
Rock, and Fox Rivers.
- Izzi
&&
.AVIATION...
For the 00Z TAFs...
615 PM CST
The main concerns include:
* Periodic light snow or snow showers late tonight through about
mid day Friday
* CIGs likely deteriorating to IFR from west to east late tonight
into Friday morning
* Reduced VSBY in -SN/-SHSN and BR, with temporary IFR VSBY
likely...can`t rule out LIFR VSBY in -SN and FG
* Another period of -SN or -SHSN possible Friday evening
Another weather disturbance will move over the area late tonight
through Friday morning. This will likely bring with it periods of
light snow or snow showers. Accumulations of a coating to a few
tenths of an inch are possible. CIGs are currently MVFR to lower
VFR and will gradually build down from west to east. As the
initial wave of -SN occurs late tonight, it appears RFD has best
chance for temporary IFR CIGs and then should go prevailing IFR by
about 12z. Farther east including ORD and MDW, confidence is
lower in IFR CIGs initially but then is high enough for TEMPO IFR
mention during the morning rush.
Increasing low level moisture along with the periods of -SN/-SHSN
will likely result in BR. In the TAFs, have prevailing MVFR VSBY
and TEMPO IFR, with adjustments likely needed as trends become
more clear. MAVMOS and especially GFSLAMP text guidance hitting
the lower VSBY harder Friday morning, with 1/2SM to 1SM VSBY. This
seems to be a lower probability scenario, but will certainly need
to monitor trends. The initial disturbance will exit east Friday
afternoon, with another disturbance dropping southeast out of
Wisconsin Friday evening and night. Flurries will be possible
through Friday afternoon and light snow possible Friday evening,
but for now with confidence low, went with a dry TAF Friday
afternoon and onward. Winds will be light through the period and
not expected to impact operations, with a general southerly
direction becoming more southwesterly Friday PM.
Castro
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
642 PM EST Thu Jan 30 2020
.SHORT TERM...(This evening through Friday)
Issued at 407 PM EST THU JAN 30 2020
WV imagery and RAP analysis indicated a split flow pattern with
mainly weak mid/upper level features affecting the Upper
Mississippi Valley and northern Great Lakes. A mid/upper level low
was located over northwest MN with weak shortwaves ahead of this
features supporting area of light snow or flurries over wrn WI.
Otherwise, persistent clouds prevailed with above average temps in
the mid 20s to around 30.
Tonight, expect generally quiet conditions with the potential for
some light snow or flurries developing into portions of central
Upper Michigan late tonight as the weak MN shrtwv edges through the
area. Forecast soundings suggest that the moisture depth, or
relatively small dry layer, will be sufficient for ice nuclei to
support mainly snow rather than fzdz.
Friday, as the shrtwv moves through, expect the limited -sn chances
to diminish by afternoon. Otherwise, even with the persistent
clouds, weak WAA will help temps climb into the lower 30s.
.LONG TERM...(Friday night through Thursday)
Issued at 336 PM EST THU JAN 30 2020
Weak shortwave moving through Friday night may spark some light
snow showers or yet even more freezing drizzle, especially as this
weak system lacks any substantial moisture. As ridging sets up
over the Plains later in the day on Saturday, expect any precip
chances to exit off toward the east. However, the Upper Great
Lakes will remain on the periphery of this ridge that will be
shifting into the GoMex later in the weekend, allowing for precip
chances to remain non-zero through Sunday morning. Should be dry
though later in the day.
The remainder of the long-term period doesn`t currently appear to
bring any appreciable precip chances to Upper Michigan, with just
sporadic, lower-end chances early next week. Above normal temps
will dominate this weekend through Monday before an Arctic airmass
ushers colder temps back in on Tuesday. The warmest day of the
period looks to occur on Sunday (40s!), dropping off to 15 to 20
degrees cooler on Tuesday (for high temps). Lows of course will
respond accordingly, with single digits perhaps making a return
Tuesday night into Wednesday morning.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 642 PM EST THU JAN 30 2020
Persistent low-level moisture will result in prevailing MVFR cigs at
KIWD/KCMX/KSAW thru this fcst period. However, MVFR cigs have
recently cleared out at KIWD, and it may not be until late tonight
that MVFR cigs return. Winds at all terminals will remain light thru
the period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 407 PM EST THU JAN 30 2020
Light winds, generally 20 kts or less, are expected across the lake
through Saturday. Look for 25-30 kt winds spreading west to east
across the lake Sunday morning (with an isolated gale force gust
possible between the Keweenaw and Isle Royale) then veering NW and
remaining near 25 kts on Monday behind a weak cold front.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...lg
AVIATION...Rolfson
MARINE...JLB
Area Forecast Discussion
National Weather Service Shreveport LA
1005 PM CST Thu Jan 30 2020
.SHORT TERM.../Tonight/
The evening water vapor imagery indicates an upper trough
extending south across the Cntrl and Srn Plains of SW TX from a
closed low center over WCntrl MN, with enough mid and upper level
forcing ahead of the trough resulting in areas of -RA and embedded
-SHRA over portions of E TX/SW AR/N LA. These areas of RA will
continue to spread E across the remainder of the region
overnight, and will result in light QPF amounts generally near or
less than a tenth of an inch. Did increase pops to high and mid
chance over areas E of the trough, while lowering/dropping pops
farther to the W over SE OK/adjacent SW AR and extreme NE TX. The
GFS and HRRR also depict cigs lowering overnight as well,
possibly as a result of patchy FG/-DZ development late in wake of
the departing trough, mainly over portions of extreme NE TX/SE
OK/SW AR, and thus have maintained mention in the forecast. Did
bump up min temps a degree or so tonight, given the lack of cold
advection, with 03Z temps/dewpoints running a degree or so higher
than the NBM/MOS.
Zone update already out...grids will be available shortly.
15
&&
.PREV DISCUSSION... /issued 543 PM CST Thu Jan 30 2020/
AVIATION...
A mix of IFR and low MVFR cigs will become IFR/LIFR later this
evening through the overnight hours, as patchy areas of -RA begin
to spread ENE across much of the region. Some vsby reductions will
be possible, although more reduced vsbys may occur between 09-15Z
Friday across portions of SW AR/NW LA/adjacent sections of E TX.
However, cigs should begin to slowly improve by late morning
through the afternoon from W to E, although cigs will remain MVFR
for the remainder of the TAF period through at least Friday
night. Light NNE winds tonight will become NW around 5kts after
15Z. /15/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 43 55 38 60 / 50 10 0 0
MLU 44 54 39 58 / 40 10 0 0
DEQ 40 53 34 58 / 10 10 0 0
TXK 40 52 37 58 / 40 10 0 0
ELD 39 54 37 58 / 40 10 0 0
TYR 42 54 35 61 / 30 10 0 0
GGG 43 55 36 61 / 50 10 0 0
LFK 45 56 39 62 / 40 10 0 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
15