Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/20/20
Area Forecast Discussion
National Weather Service La Crosse WI
1015 PM CDT Thu Mar 19 2020
.SHORT TERM...(This evening through Friday)
Issued at 216 PM CDT Thu Mar 19 2020
Water Vapor imagery this afternoon depicts two distinctive upper-
level systems - a positively tilted shortwave trough over the
Central Plains and a large scale trough located over Manitoba. The
southern stream system is responsible for the widespread
rain/storms we are experiencing this afternoon as a surge of
moisture transport, precipitable water values of 0.75 to 1.00
inch, and warm air advects northward ahead of it. This surface low
will continue to lift into the the Great Lakes Region tonight,
bringing with it continued chances for showers and some storms,
mainly south of Interstate 90. As the low progresses further
north, the northern stream trough will dive southeastward and push
the southern stream system eastward while they phase together.
Deterministic models started to agree on the eastward shift
yesterday, with high res models jumping on board today. Because of
this, the threat for strong to severe storms continues to be
shunted further east. The latest RAP runs and 19.12Z HREF are also
on board with this as they continue to nudge the better
ingredients further south and east of the local area where the
warm sector will be located. MUCAPE values on the order of maybe
200-400 J/kg at best look to just barely reach portions of far
northeast Iowa and southwest Wisconsin this evening. This, paired
with mid-level lapse rates of 6-7 C/km and some influence from the
left exit region of an upper-level jet may be just enough to
produce a strong storm or two, with hail and lightning being the
main threats of concern. However, confidence continues to increase
that the threat for a strong storm or two is rather low. Per
collaboration with SPC, have shrunk the slight risk to only cover
extreme southern parts of CWA.
Our taste of springtime rain showers and storms on the first day
of Astronomical Spring will be brief as the northern stream system
plows through the area tonight, bringing with it colder
temperatures and some mid-March snowfall. Precipitation will
transition from rain to snow as temperatures cool and a strong low
to mid-level frontogenetic band develops. Generally around 1-2
inches of snowfall look likely across areas near and north of
Interstate 90, with lesser amounts further south. The 19.12Z HREF
continues to have a few members depicting some isolated higher
amounts across parts of southeast Minnesota, which seems possible
with the strength of the frontogenetic band. However, exact
placement of said higher amounts will need to be refined once the
band of snow develops later this evening. Although the entire area
may not see accumulating snowfall, any residual moisture on
roadways from the widespread rainfall today may flash freeze as
temperatures rapidly cool tonight. This may result in slippery
spots and travel impacts for the Friday morning commute.
Additional liquid accumulations from this afternoon into tonight
look to range between 0.50 and 1.00 inch. This on top of what has
fallen over the last few days will lead to rises on area rivers.
.LONG TERM...(Friday night through Thursday)
Issued at 216 PM CDT Thu Mar 19 2020
The upper level flow will become quasi-zonal after the passage of
the system tonight. The models have been advertising a northern
stream short wave trough dropping out of western Canada and moving
across the Upper Midwest and the 19.12Z model suite continues this
trend but has sped up the timing. This wave now looks like it
cross the region Saturday night into Sunday and come with enough
forcing to possibly produce some light precipitation. Because of
the zonal flow, the moisture return ahead of the wave will be very
limited and thus only some very light snow looks to be possible
with this system.
This system will then usher in a period of on/off precipitation
chances that will continue through much of next week. The next
system in the northern stream looks to primarily stay across
Canada with the southern tip of the troughing coming close enough
to the Upper Midwest to possibly produce some more light
precipitation Sunday night and Monday. After the passage of this
system, the overall agreement between the models starts to
decrease on timing/placement/strength of subsequent systems. The
general idea is that an upper level low over the Pacific this
weekend will move onshore and weaken as another system drops south
out of the northern Pacific. The remains of this system should
then move across the Midwest somewhere in the Monday night through
Tuesday night time frame. The precipitation chances look to be
higher with this system as the forcing will be stronger and should
have more of a direct impact on the area. Behind this system, the
upper level flow looks to become southwest as the norhtern Pacific
system continues to drop southeast into Desert Southwest. The
models are suggesting that various short wave trough coming out in
the this southwest flow will maintain the precipitation chances
into late next week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1015 PM CDT Thu Mar 19 2020
IFR conditions with a period of -SN is expected at KRST with -RA
changing to -SN at KLSE. Lingering snow should exit by 09 to 11Z
with conditions trending VFR during the day with clearing skies.
Winds will gust to 25-35 kts into early Friday before slowly
diminishing.
&&
.HYDROLOGY...
Issued at 216 PM CDT Thu Mar 19 2020
The system moving across the region tonight still looks to have
the potential to produce some widespread rainfall amounts of 1 to
1.5 inches. A good share of this rain should be turned into runoff
from still partially frozen ground and what is thawed, being
saturated from earlier rains Tuesday night. Given this set up,
expect rises to occur on almost all area streams and rivers with
the possibility of flooding occurring. Right now, the highest
probabilities for flooding look to be for the tributaries across
western Wisconsin and maybe a few in northeast Iowa. Most of this
should be minor flooding, but contingency forecasts with maximum
potential rainfall indicate moderate flooding is not out of the
question. The mainstem of the Mississippi River will also see
rises with some minor flooding possible next week.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...NMB
LONG TERM...04
AVIATION...JM
HYDROLOGY...04
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
140 PM CDT Thu Mar 19 2020
...WE ARE NOW MONITORING RADAR AS SCT TSTMS ARE DEVELOPING...
.SHORT TERM...(This evening through Friday)
Issued at 140 PM CDT Thu Mar 19 2020
Plan to keep this brief to maximize availability for monitoring
radar.
Be sure to follow SPC SWOMCD`s and any Watches as svr tstms could
occur before sunset.
Aloft: RAP tropopause analyses/WV imagery/aircraft wind obs
indicated a trof over the Wrn USA with a ridge over the GlfMex. A
potent shrtwv trof was embedded within the Wrn trof over CO and
lifting NE into NEB/KS. This trof will cross the CWA this eve.
Behind this trof...a minor shrtwv ridge will arrive by dawn Fri
with low-amplitude WSW flow evolving overhead Fri.
Surface: 998 mb low pres was along the CO-KS border with a strong
warm front extending ENE thru Srn NEB into IA. This front does
bisect the CWA just N of the KS state line. A strong cold front
was over the Nrn plns. This front will move S this afternoon. The
2 fronts will merge and the combined front will accelerate SE away
from the area this eve. The push will be provided by a strong
1040+ mb high over Cntrl Canada which is sinking S. This will
strengthen the pres grad over the rgn tonight. The low will weaken
and a new low will evolve over the GtLks tonight...while the high
sinks into the Nrn Plns. The high will remain there tomorrow.
Rest of this afternoon: Cldy N of the front and mostly sunny to
the S. Expect sct tstms to form espcly near the front. Some storms
could be svr. This will be a low CAPE/higher shear scenario.
Mainly looking like a hail and gusty wind type event. The risk of
a tornado is low as winds will be unidirectional in the warm
sector. Best shear will be on the cold side of the front.
Tonight: Rain changes to brief 3-6 hr period of snow as cold air
slams in here. Snow will essentially be done by midnight or
shortly thereafter. Windy! N winds 25-35 mph with G50. Rapid
clearing from N-S after midnight.
Fri: Sunny. Cold. Diminishing winds.
.LONG TERM...(Friday night through Thursday)
Issued at 140 PM CDT Thu Mar 19 2020
Aloft: No change in the longwave pattern we`ve seen since mid
Nov...with a trof over the Wrn USA and a ridge over the E. This
will generally translate to continued low-amplitude WSW flow over
NEB/KS. A wk shrtwv trof is fcst to cross the rgn Mon night into
Tue. The last 2 runs of global mdls are in good agreement that the
flow will amplify some late next wk...with the flow turning SW
Thu as the Wrn trof becomes mobile and gets closer.
Surface: The Nrn Plns high will gradually move E thru the wknd
with return flow developing here. A wk cool front is fcst to move
thru Sun night. Multiple lows will then form over the Cntrl US/Can
Tue-Wed. The two that will probably affect the CWA will be Mon
night into Tue...with no cool air behind it...and then Wed night
and there will be a cooldown behind that low.
Temps: Normal daytime highs are low 50s. Temps will be at or
above normal thru next Thu...mostly above normal.
Precip: A couple chances for very light wintry mix or shwrs with
embedded non-svr tstms. Am holding off on much elaboration due to
impending tstm development this afternoon.
&&
.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Friday)
Issued at 140 PM CDT Thu Mar 19 2020
Significant Wx: IFR with sct +TSRA this afternoon.
This afternoon: IFR CIGs and variable VSBYs between MVFR and IFR.
Sct +TSRA are developing. Not sure either terminal takes a direct
hit...but it`s psbl. NNE-N winds gradually incrs 25-35 kt.
Confidence: Medium
Tonight: IFR CIGs/VSBYs as rain changes to snow. Some wet accum
psbl before ending around midnight. De-icing will be required. N
winds increase to around 30 kt with G40-45 kt at times. Rapid
clearing and becoming VFR after midnight. Confidence: High
Fri thru 18Z: VFR. No clds at or below 10K ft. N winds gradually
diminish to 10-20 kt. Confidence: High
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 7 AM CDT Friday for NEZ039>041-046-
047-060-061.
KS...NONE.
&&
$$
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Kelley
Area Forecast Discussion
National Weather Service Grand Rapids MI
813 PM EDT Thu Mar 19 2020
LATEST UPDATE...
Update/Aviation
.SYNOPSIS...
Issued at 236 PM EDT Thu Mar 19 2020
- Marginal risk of severe weather overnight
- Windy and colder Friday
&&
.UPDATE...
Issued at 814 PM EDT Thu Mar 19 2020
The threat for severe storms seems to be decreasing from what we
though earlier. If there were a threat it would be south of a arc
from Holland to Battle Creek (more or less). I have just called
SPC and they agree that the severe storm threat has decreased over
Lower Michigan. The latest RAP model shows 2200 j/kg of mix layer
cape where the storms currently are in Iowa, by the time that
area gets to Michigan it`s more like 200 to 400 j/kg of Mixed
layer cape. The trend in the SREF of the conditional probability
of severe storms which on the 06z run had 20 pct into Southern Van
Buren county, has now fallen with the 15z run to 5 pct over
southern Van Buren County. The only thing to watch is the track of
the surface low may be close enough to this area that we may see
a few strong storms even so. My bottom line is the threat seems to
be higher closer to I-80 than I-94.
&&
.DISCUSSION...(This evening through next Thursday)
Issued at 236 PM EDT Thu Mar 19 2020
- Marginal risk of severe thunderstorms overnight
First batch of rain moves through this evening with some embedded
thunderstorms in limited elevated instability. Then the dry slot
moves in but surface based instability in the warm sector could
help development of a line or small clusters of thunderstorms
between midnight and 4 am, shown by some runs of the NMM, and ARW
convective allowing models. Given strong shear profiles, any
persistent and organized storms have the potential to produce
wind damage.
- Windy and Colder Friday
Cold advection behind the front on Friday will mix down some winds
in the 30 to 40 mph range and temperatures will tumble into the
30s with wind chills below freezing by afternoon. Some lake
effect snow showers are possible across the northwest.
Active wave train continues next week but any threat of
significant impacts from severe or winter weather looks low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 814 PM EDT Thu Mar 19 2020
Expect IFR conditions most of the night due to low ceiling and
low visibilities. Once the cold front comes through for the most
part MVFR cigs and gusty winds will prevail most of Friday during
the day.
There is the threat of a few thunderstorms between 03z and 08z
but that threat is not all that high. I removed the VCTS from JXN
and LAN and it`s questionable at MKG and GRR. If any of our TAF
sites were to see thunderstorms, it would seem AZO and BTL would
have the greatest risk. Even there the SPC SREF has between a 20
and 30 pct chance of a thunderstorm between 03z to 06z.
A classic early spring storm is tracking through the Great Lakes
this evening. The warm front has brought rain across our TAF sites
with IFR conditions in rain, fog and low ceilings. The rain band
will lift north of the TAF sites but scattered showers will likely
continue through the evening. A area of convective showers is
likely in the 03z to 08z time frame as the cold front moves
through but based on the HI RES models that threat is more so over
the southwest CWA than anywhere else. Once that is done expect
low clouds and breezy conditions with strong wind shear near 2000
ft agl. Three is a risk the snow showers trailing the system
could get as far south as MKG and GRR by mid morning Friday but
the threat did not seem high enough to put in the TAFs.
&&
.MARINE...
Issued at 258 PM EDT Thu Mar 19 2020
No changes to the Gale Warning as gusts to 35 knots are expected
Friday morning then decreasing in the afternoon. The Gale Warning
could probably be downgraded to a Small Craft Advisory in the
afternoon.
Minor beach erosion and flooding is expected Friday morning but
conditions should be improving as the winds decrease and begin to
shift offshore during the afternoon.
&&
.HYDROLOGY...
Issued at 258 pM EDT Thu Mar 19 2020
We still expect about one half to three quarters of an inch basin
wide average QPF tonight which would cause some rises to near
bankfull on the mainstem rivers the next few days. At this point
it does not appear that flooding is likely except in areas where
some training of thunderstorms occurs. The potential for this is
greatest in the Kalamazoo River Basin.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Lakeshore Flood Advisory from 8 AM to 8 PM EDT Friday for MIZ037-
043-050-056-064-071.
LM...Gale Warning from 8 AM to 8 PM EDT Friday for LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...WDM
HYDROLOGY...Ostuno
MARINE...Ostuno
Area Forecast Discussion
National Weather Service Gray ME
1015 PM EDT Thu Mar 19 2020
.SYNOPSIS...
Low pressure passes off the New England coast tonight continuing
light rain and drizzle. Rain showers and a few storms are
possible tomorrow, then a cold front crosses late in the evening
into the overnight hours. High pressure with colder and drier
air arrives for the weekend through the start of next week. Rain
or snow is possible late Monday into Tuesday morning.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
1015 PM Update...Just a few minor adjustments to the going
forecast as it remains on track.
745 PM Update...Little change to the going forecast for the next
several hours. Areas of fog and drizzle will be the rule for
most of the forecast area this evening and overnight. Have added
a little bit of freezing rain to the western ME mountains as
temperatures in some spots are hovering around 32F around 2000
FT in elevation. Not expecting anything more than patches of it,
so not advisory at this time.
Previously...
Humid and dreary weather continues through the evening and
overnight hours as low pressure lingers off the New England
coastline. At the current hour, RAP analysis places the center
of low pressure just south of Nantucket with model consensus
bringing it ENEward through the Gulf of Maine overnight. This
keeps onshore flow going with light rain and drizzle over the
coastal plain, aided by a 40kt h925 LLJ. While the temperature
inversion keeps most of the energy well aloft, a few gusts
around 20 kts are possible along the immediate coast this
evening.
Looking at the broader picture, column thickness continues the
days-long upward trend as strong southwest flow increases aloft.
Upstream, a trough extending from the Hudson Bay region down
into the southern Plains tracks a surface low across the
northern Great Lakes basin tonight. Warm frontal forcing ahead
of it brings the next round of rain showers into our area from
the west just before dawn.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Late Friday morning, a surface warm front pushes north across
New Hampshire and into southern Maine with scattered shower
activity. The front is forced north by a surging mid-level jet
of around 50-60 kts at h850. In spite of afternoon temperatures
rising well into the 60s to near 70 in the warm sector, BUFKIT
soundings suggest strongest winds aloft remain above the mixed
layer in the warm sector. A few wind gusts in the 20-30 kt
range are possible should breaks in the clouds allow the surface
to warm, but in general momentum transfer in convection would be
the best bet to mix strong wind gusts to the surface.
Regarding convective chances...low-topped storms are possible
with both warm frontal forcing and eventually with cold frontal
passage. In general storms won`t be widespread, and I`m certainly
not expecting widespread strong storms. Though, there is plenty
of wind energy aloft to drive lines of gusty showers with some
rumbles of thunder. Heavy rainfall is also likely in convection
as PWAT tops 1.25" over much of the area.
Surface low pressure tracks into eastern Quebec by the end of
the day, dragging a cold front across New England late in the
evening, ushering in a dry trend after what may be one last line
of showers and storms. In general though storm chances decrease
with the diurnal trend. Cold advection behind the front will
allow for better mixing of gusty winds to the surface, maxing
out on the order of 25-30 kts. Upslope rain showers switch to a
brief bout of snow showers over the mountains before drying
entirely by dawn.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
The 500 MB hemispheric pattern is poised to provide something we
haven`t seen much of over the winter, downstream blocking over the
NO Atlantic and Europe, although it maybe too far downstream to have
a significant effect on nrn New England. Still, it will provide
several rounds of precip, and temps bouncing between normal and abv
normal, once the cold sfc high moves out after the weekend.
The weekend will be mainly sunny and cold as high pressure moves in
behind the low exiting to our NE across maritimes. IT`ll still be
breezy on saturday, but winds should subside somewhat on Sunday.
Highs on Saturday will be in the 30-35 range in the mtns and 40-45
in the south. Sunday, although less windy, will be a little cooler,
as mixing will be limited with highs in the low to mid 30s N, to
around 40 in the south.
Monday should start off decent, but approaching compact 500 MB wave
should produce low pressure offshore. System is potent but small,
and will be fast moving, so QPF looks light, but p-type could be an
issue Mon night into Tuesday morning, especially in inland areas of
ME and central and nrn NH. Should see a brief break on Wed as high
pres builds in with temps warming up some. The end of the looks
unsettled attm, as several waves move through lightly cyclonic flow
aloft.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term...Onshore flow keeps low ceilings into into tonight
with -RA/BR/DZ/FG reducing visibility especially along the
Maine coast. CIGS will tend to fill in and lower to IFR and
LIFR, especially as a warm front approaches from the south
Friday morning. A strong jet aloft brings a warm front from
south to north late Friday morning while also producing a period
of SWerly LLWS into the afternoon. Scattered showers and a few
storms are possible Friday, then a cold front crosses late in
the evening with gradual improvements overnight, except for at
HIE where upslope flow continues MVFR into the morning hours.
Long Term...Mainly VFR conditions expected Sat-Mon. Could see
some flight restrictions in RA/SN Mon night into Tuesday.
&&
.MARINE...
Short Term...Low pressure off the New England coast increases
seas over the waters and Casco Bay to 5-10 ft with wind gusts
20-30kts. Conditions briefly improve as low pressure pulls away
Friday with scattered showers and a few storms possible, then a
cold front crosses Friday evening with winds turning offshore
and increasing seas again. Expect SCAs to persist through the
entire short term period.
Long Term...SCA winds/seas likely to persist through Saturday,
but will begins to diminish Sat night, and should stay blo
criteria into Monday. May need SCAs again Mon night or Tue.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 4 PM EDT Friday for ANZ150-152>154.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
747 PM EDT Thu Mar 19 2020
.SHORT TERM...(This evening through Friday)
Issued at 456 PM EDT THU MAR 19 2020
A strengthening storm system will track from the Central Plains this
afternoon into the Upper Great Lakes tonight as light rain
transitions to wet, and at times, heavy snow this evening continuing
into Friday morning, with several inches of wet heavy snow likely
over the west and central U.P. tonight.
Water vapor imagery and RAP analysis show a split flow pattern over
western N America. In the southern stream, a mid-upper level trough
is situated over the West Coast with a very well-defined shortwave
moving through the Central Plains which will be the feature of
interest for our forecast area tonight into early Fri as it races ne
ahead of a northern stream shortwave dropping se toward the Upper
Lakes.
As the central Plains shortwave and associated sfc low lift into WI
and then toward the Mackinac Straits tonight, winds will shift to
the north and CAA will drop temps through the column, transitioning
precip to snow across the region. Coupled upper jet structure with
one jet max over northern Ontario and northern Quebec and another
nosing into the mid-Mississippi Valley/Midwest will lead to
strengthening fgen especially during the evening hours across the
U.P. This strong forcing along with ample moisture should enhance
pcpn totals in the late afternoon/evening hours. Widespread liquid
equivalent precipitation of 0.75 to 1.00 inches is expected by
Friday morning. Models have trended slightly farther east with the
best area of heaviest synoptic pcpn moving through the central U.P.
this evening.
The challenge with the forecast will be determining when the
changeover to snow occurs as models the last few runs have trended a
bit colder with low level temps, and it looks like the change over
to snow appears to be a few hours earlier this evening, supported by
strong lift and adiabatic cooling. The window for heavy synoptic
snow is relatively short, mainly this evening, over a 4-5 hour
period. Current indications are for the changeover to snow to
occur 23-00Z from MQT to Crystal Falls and west, then slowly
change over from west to east over the remainder of the U.P late
tonight through Fri morning.
Lake enhancement will also play a key role tonight as strong
northerly winds advect cold air with 850 mb temps lowering to around
-16C by Fri morning over Lake Superior. Models indicate some
lingering synoptic forcing over the lake into Fri morning which
should enhance lake effect snow totals.
The combination of snow, strong winds and blowing snow will continue
to warrant winter weather headlines. Snow and wind will make travel
difficult and also concerns for isolated power outages with the snow
being very wet early on, weighing down trees and powerlines.
Forecast snow amounts are generally 2 to 4 inches over the interior,
3 to 7 for the snowbelts and up to 8 in the highlands. Given the
trend for heavier qpf to shift slightly farther east will keep
winter weather advisories going over the west and south central
counties, but have decided to upgrade advisories to winter storm
warnings over Baraga, Marquette and Alger counties to account for
the moderate to possibly heavy snow, gusty north winds 35-45 mph
causing blowing snow and poor visibility later tonight into Friday.
The Friday morning commute will probably be pretty miserable with
the lake enhanced snow and blowing snow, especially for Highway M-28
from Marquette eastward.
Will continue lake shore flood advisories/warnings as wave heights
reach 12 feet in the west and 18 feet central late tonight into
Friday, expect beach erosion along ice free shorelines and flooding
in typical problem areas. Ice could also be pushed onshore.
.LONG TERM...(Friday night through Thursday)
Issued at 308 PM EDT THU MAR 19 2020
Over the next 7 to 10 days, strong positive height anomalies/ridging
will be present over the N Pacific with the max anomalies varying
btwn the Gulf of Alaska and the Aleutians, but mostly over the
Aleutians. This will force troffing in the mean generally in the
vcnty of the W Coast. Meanwhile, late season bitter cold air will
expand across northern Canada under a large, deep mid-level low
settling s into n central Canada. At this point, medium range
guidance suggests upstream ridging will never become amplified
enough to force this cold air s toward the Great Lakes. In any
event, should be an active pattern across the Lower 48 as shortwaves
round the N Pacific ridging into the western trof and then eject e
and ne across the U.S. while other shortwaves swing around the large
mid-level low dropping into n central Canada. One system will track
ene across the area later today thru early Fri, bringing rain/snow.
In its wake, strong high pres will provide a dry weekend. A little
-ra/-sn will be possible early next week as a weak shortwave
swings along the U.S./Canada border region. A stronger wave will
eject from the western trof heading into the midweek period, but it
should pass far enough s of the area so that the main pcpn shield
passes by to the s of Upper MI. During the late week period, recent
days model runs have at times indicated that another wave ejecting
from the western trof would track into the Upper Lakes, providing
the potential of significant pcpn, rain and/or snow. Will be
something to monitor down the road. In the meantime, models will
struggle with timing of ejecting waves out of the western trof, the
amplitude/timing of shortwaves swinging around the deep Canadian mid-
level low, and the potential interaction btwn the 2 streams of flow.
As for temps, blo normal temps will follow the system passing
tonight with Fri the coldest day. Temps will moderate back toward
normal for Sun. During next week, temps will likely be a little
above normal on most days.
Beginning Fri night, strong sfc high pres over the Northern Plains
will shift east toward the western Great Lakes. Low-level n to nw
flow ahead of the high and 850mb temps of -15 to -18C across Lake
Superior support the potential of LES, but only into the eastern
fcst area under longer fetch and colder air. Typical for late season
LES, fcst soundings show a fairly pronounced inverted-v look (a
negative for LES) due to the building mixed layer that occurs during
the daytime upstream of the lake. Since the DGZ occupies the total
cloud layer, capped by an inversion around 5kft, should be able to
generate some flurries or a few -shsn from near Marquette eastward
Fri night and perhaps lingering into Sat morning. To the w,
potential is there for a cold night. If lake clouds are limited,
combination of a dry air mass with precipitable water around 30pct
of normal and winds diminishing toward calm will allow for a strong
radiational cooling night. Opted to drop temps toward the bias
corrected CMC which is normally a superior performer in radiational
cooling situations. So, fcst reflects lows around zero in that area.
If it ends up being a clear night, temps could easily drop to -10F.
High pres moves across the area on Sat and shifts to southern Quebec
on Sun, providing a dry period. Highs in the mid 20s to the lower
30s on Sat will rise to the lower 30s to around 40F on Sun.
Shortwave swinging along the U.S./Canada border will bring a chc of
-shsn Sun night and -shsn/-shra on Mon. There will be a couple more
opportunities of some rain/snow next week. Fcst currently reflects
rather broad coverage of chc pops due to timing uncertainties, but
right now it appears Wed night/Thu has the best chc of some pcpn.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 737 PM EDT THU MAR 19 2020
KIWD and KCMX have already switched over to snow, with snow
mixing in, if not already entirely switched over at KSAW by the
time this is read. For the duration of the night, the main issues
for aviation interests will be the reduced ceilings, the reduced
visbys, and soon to move in, the increased northerly winds that
will produce noteworthy gusts, especially closer toward daybreak.
Expect some improvements after sunrise on Friday, although snow
showers will still linger in and around the terminal areas. By
later in the afternoon, conditions across the board will improve.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 456 PM EDT THU MAR 19 2020
Low pres will streak from Colorado today, across the Straits of
Mackinac tonight and into southern Quebec on Fri. With strong high
pres building into the Northern Plains in the wake of the low, N
gales of 35-45kt will develop from w to e across Lake Superior
tonight, continue into Fri morning, then diminish to blo gale force
from w to e Fri aftn thru early Fri evening. The strongest winds
will occur across a wide swath of central Lake Superior. Not out of
the question that few a storm force gusts could occur late
tonight/Fri morning. Along with much colder air surging into the
area, expect hvy freezing spray for all but far western Lake
Superior on Fri. Winds will become light for Sat, under 15kt, as
high pres passes across the area. S to SE winds will then increase
to 15-25kt across much of Lake Superior Sun into Sun night as the
high exits and a weakening low pres trof approaches. Winds will then
diminish some on Mon as the trof dissipates while crossing Lake
Superior.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 2 PM EDT /1 PM CDT/ Friday for
MIZ001>003-009-084.
Lakeshore Flood Advisory from 2 AM to 2 PM EDT Friday for
MIZ001>003.
Lakeshore Flood Warning from 5 AM to 8 PM EDT Friday for MIZ005-
006.
Winter Storm Warning until 5 PM EDT Friday for MIZ004>006.
Winter Weather Advisory until 7 AM CDT Friday for MIZ010-011.
Lake Superior...
Heavy Freezing Spray Warning from 6 AM to 8 PM EDT Friday for
LSZ243>245-248>251-263>267.
Gale Warning from 7 AM to 8 PM EDT Friday for LSZ251-267.
Gale Warning from 2 AM to 8 PM EDT Friday for LSZ245>250-265-266.
Gale Warning from midnight tonight to 8 PM EDT Friday for LSZ243-
244-264.
Gale Warning from midnight EDT /11 PM CDT/ tonight to 4 PM EDT
/3 PM CDT/ Friday for LSZ240>242-263.
Gale Warning from midnight EDT /11 PM CDT/ tonight to 11 AM EDT
/10 AM CDT/ Friday for LSZ162.
Lake Michigan...
Gale Warning from 7 AM to 8 PM EDT Friday for LMZ221-248-250.
&&
$$
SHORT TERM...Voss
LONG TERM...07
AVIATION...lg
MARINE...Voss
Area Forecast Discussion
National Weather Service Pueblo CO
926 PM MDT Thu Mar 19 2020
.UPDATE...
Issued at 922 PM MDT Thu Mar 19 2020
Updated to take down highlights across the Pikes Peak region...
Heavier snow has come to an end and visibility has improved in web
cams across northern El Paso county. Therefore have taken down the
Blizzard and Winter Storm Warning at 9 PM. Light snow continues
to fill in across the southeast mountains and adjacent lower
slopes as low level flow shifts around to the northeast. Not much
showing in web cams yet along I-25 and Highway 160 over La Veta
Pass, though VTP sensor is showing pretty low vis in +SN in the
past hour. Will maintain winter weather advisories for the Sangres
for a bit longer to account for some patchy heavier snow. HRRR
has this diminishing towards 06z so suspect that highlights will
be taken down around then. -KT
UPDATE Issued at 605 PM MDT Thu Mar 19 2020
Updated package to allow headlines out west to expire. Still
snowing out that way, but visibility in web cams have improved and
additional snowfall will be light. -KT
&&
.SHORT TERM...(This evening through Friday)
Issued at 303 PM MDT Thu Mar 19 2020
...Storm to continue into this evening...
Currently...
Major winter storm affecting parts of the region at this hour. So
far the biggest winner has been Woodland Park with 10 inches. USAFA
has observed blizzard conditons, with general 4-6" amounts in parts
of N El Paso county. Radar at 2 pm continues to show heavy snow
falling across far N El Paso county, with snow intensities
decreasing a bit farther south due to downsloping winds off the
Palmer Divide. Over the remainder of the plains, it was quite windy
although the winds have slackened off a bit from earlier today. Far
southeast CO mostly sunny and relatively mild, albeit it was windy.
Temperatures were in the 60s over far southeast CO while they were
in teh U20s over N El Paso county. San Luis Valley (SLV) had temps
in the 40s.
Rest of today into tonight...
Blizzard conditions will likely continue across far N El Paso county
(crest of Palmer Divide) into the evening hours, with heavy snow and
wind gusts in the 35 to 40 mph range. Snow farther south will
gradually decrease as downslope component overcomes synoptic lift
associated with the cyclone. Another area of concern will be the
east slopes of the S mtns as guidance shows some decent upslope
developing later today into tonight, and we will likely see a few
inches of new snow this evening.
As for winds, winds will transition from strong NW to modest
northerly flow over the plains tonight, with northeasterly winds
closer to the mtns.
Temps tonight will fall into the upper teens to L20s across the
plains and valleys and single digits and 10s in the mtns.
Over the remainder of the high terrain, unsettled conditions will
continue with the trough lagging back, and this will keep a chance of
snow showers over the higher terrain through the night.
Tomorrow...
Plains should be primarily dry through the day, although I cant rule
out some snow showers rolling off onto the adjacent plains during
the afternoon. Temps over the lower elevations tomorrow will be
cool, with readings in the 30s and 40s. With high pressure building
down the High Plains, a synoptically induced upslope flow will
develop.
Over the mtns it will be more active. With troughieness still to our
west and the jet just to our south, weak upward vertical motion will
occur within a rather moist airmass. This should allow snow showers
to continue across the region, especially across the mtns along the
CONTDVD. A few inches of new snow will be possible tomorrow over the
higher terrain. Temps over the valleys tomorrow will be in the 40s
valleys and 20s mtns. /Hodanish
.LONG TERM...(Friday night through Thursday)
Issued at 303 PM MDT Thu Mar 19 2020
Friday night-Sunday...Moderate west to southwest flow aloft progged
across the region through the weekend with the latest models
continuing to indicate an embedded short wave translating across the
southern Rockies through the day Saturday and another embedded wave
translating across the northern Rockies on Sunday. With that said,
isolated to scattered showers over and near the higher terrain
Friday afternoon to diminish and end through the evening, with more
afternoon showers across the higher terrain expected Saturday
afternoon, with a showers, and a few possible thunderstorms,
developing across the southern I-25 Corridor through the far
southeastern plains Saturday afternoon and evening. On Sunday, drier
conditions expected across most of the area, save for shower chances
across the central mountains Sunday afternoon. Should see temperatures
warming back to near seasonal levels through the period.
Monday-Thursday...Moderate westerly flow aloft progged to continue
across the region into the middle of next weak, with a few embedded
short waves translating across the region. This will keep isolated
to scattered pops across the higher terrain, especially along the
ContDvd, with mainly dry and breezy conditions across the plains.
With temperatures expected to be at and slightly above seasonal levels,
could see near critical fire weather conditions at times across
the plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 303 PM MDT Thu Mar 19 2020
Unsettled conditions are expected tonight over the greater southern
Colorado region and this will keep clouds and snow showers possible,
along with occasional low cigs at the taf sites. The strong gusty
winds at the taf sites will decrease this evening, with flow
becoming upslope late tonight. This may induce some lower cigs over
KCOS and KPUB late tonight. Snow showers over KALs tonight may bring
in some brief periods of MVFR. For tomorrow, morning MVFR/IFR
conditions at KCOS and KPUB should give way to VFR by mid to late
morning. Passing snow showers will be possible at KALS tomorrow.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MDT tonight for
COZ072>075.
Winter Weather Advisory until 6 AM MDT Friday for COZ058>061-063.
&&
$$
UPDATE...KT
SHORT TERM...HODANISH
LONG TERM...MW
AVIATION...HODANISH
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Friday)
Issued at 324 PM CDT Thu Mar 19 2020
The region undergoes a rapid change from summer to winter weather
in the next 24 hours.
As of 20Z, still monitoring far northern and northeastern Kansas
near the triple point of an rapidly advancing dryline and warm
front for convective development. The warm front current extends
from near Hebron to Nebraska City, with the leading edge of the
dryline extending southeastward from Republic to Lyon counties in
low-level water vapor imagery. There is only a few more hours
remaining before the warm, moist air is pushed east of the
forecast area, and much of the severe weather with it. The west-
to-east oriented CU field along and south of the warm front has
become increasingly agitated in the last hour, with multiple
convective cells developing and tracking northward over the front
and into Nebraska.
Despite ample destabilization in the warm sector ahead of the
dryline, the veered wind profile ahead of the boundary minimizes
the amount of convergence ahead of it. The lack of any appreciable
CU along this boundary is a strong indication of just how little
lift it is providing. Will continue to monitor the dryline as it
moves through, but with continuing runs of the HRRR devoid of any
significant convective signatures and satellite signatures very
unimpressive, any threat along this line is INCREDIBLY
conditional. The best severe threat is more likely closer to the
warm front in southeast Nebraska. The overall warm sector CAPE/shear
environment would support supercellular structures, if any storms
do manage to form.
Did cancel the eastern portion of the wind advisory for this
afternoon given that the deepest mixing should be confined to
areas along and west of the Flint Hills. The going wind advisory
for this afternoon will likely be ended around 23 or 00Z depending
on how fast conditions improve ahead of the approaching cold
front. A very high fire danger also exists along and west of the
Flint Hills this afternoon owing to deep mixing and RH values
falling to 25 to 30 percent.
As the upper level pattern shifts eastward, the surface low
responds by advancing across the forecast area, dragging a sharp
cold front across the region early tonight. Southwest winds
lessen ahead of the front, but quickly increase out of the north
to 20 to 30 mph with gusts over 40 mph at times through the night.
Did issue a wind advisory for tonight with the combination of a
strong pressure gradient and differential CAA through the BL
keeping winds going throughout the night. Temperatures nose dive
behind the front with the decaying deformation zone drifting
through overnight as well. Can`t rule out some light precip as
this band of moisture moves through, but impacts should be
negligible. Wind chills by Friday morning fall into the single
digits to teens and temperatures only recover into the 20s to low
30s during the day.
.LONG TERM...(Friday night through Thursday)
Issued at 324 PM CDT Thu Mar 19 2020
After a cold start to the weekend, a moderating pattern settles
in through the middle of the week with multiple rounds of
precipitation possible.
The mean west coast longwave trough characteristics vary over the
course of the extended period, but for the most part the trough
remains in place for the forecast period. This will promote both a
moderating west to southwest flow pattern and a series of energy
lobe ejections that will bring chances for precipitation. The
first such system arrives Saturday night into Sunday, and the next
Monday into Tuesday. The details of these systems are still a bit
too uncertain to hash out at the present time. Highs rebound back
into the 40s and 50s for Sunday, reaching back into the 60s early
in the week and even possibly the 70s by midweek.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 721 PM CDT Thu Mar 19 2020
Expect VFR conditions at across the terminals for most of the
evening hours. a Surface cold front will move across the area
after 3Z and stratus with MVFR ceilings of 1000 to 1500 feet will
over spread the terminals during the late evening hours towards 6Z
FRI. There may be low-level windshear of 30 KTS ahead of the
front early this evening. Behind the front, north winds will
increase to 20 to 30 MPH with some gusts of 30 to 40 MPH.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 5 AM CDT Friday for KSZ008>012-020>023-
034>036.
&&
$$
SHORT TERM...Skow
LONG TERM...Skow
AVIATION...Gargan