Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/21/19
Area Forecast Discussion
National Weather Service Amarillo TX
619 PM CST Wed Nov 20 2019
.AVIATION...00Z TAFS...
VFR conditions will prevail at all terminals through 18z.
Thereafter MVFR/IFR conditions will be possible as the next
weather system moves in. Rain will be the most likely form of
precipitation for KAMA. RASNPL will be possible at KDHT as this
will be where the highest impacts could occur. KGUY not far
behind, but for now it looks like just rain for the 18-00z time
period, but will not be surprised after 00z if a change over to SN
occurs at KGUY. Winds out of the southwest will begin to diminish
over the next few hours, and north winds around 10kts can be
expected between the 7 to 10z period.
Weber
&&
.PREV DISCUSSION... /Issued 400 PM CST Wed Nov 20 2019/
SHORT TERM...Today through Tomorrow...
Satellite imagery of mid-level water vapor and 500mb heights show
the closed low cutting south across the coast of California this
afternoon with waves of moisture being ejected out ahead of the
trough. By early afternoon, the upper level wave will cut east
across southern Nevada through the morning hours Thursday. A
shortwave pushed across this morning, which brought the showers
through the area and kept temperatures in the upper 50s with low
cloud cover. However, skies are clearing from southwest to
northeast with temperatures starting to rise again. The northwest
corner of the Texas Panhandle and portions of the eastern
Oklahoma Panhandles are mixing down wind speeds of 25 to 30 mph
with gusts up to 40 mph. If the southern Texas Panhandle is
capable of clearing this afternoon and temperatures rise into the
upper 60s to lower 70s, there is a potential for a severe storm or
two to pop up. RAP analysis shows instability of 500-1000 J/kg of
MLCAPE and 60 knot 0- 6 km effective bulk shear around 21z mainly
in the far southeast Texas Panhandle. Dewpoints have the
potential to rise into the 60s as the precipitation and skies
clear out. An isolated strong storm or two cannot be ruled out
with hail and damaging winds as the main threats. Precipitation
chances will diminish after 00z with only a chance for lingering
isolated storm on the far southeast Texas and Oklahoma border.
Minimum temperatures will drop below freezing in the northwest
half of the combined Panhandles, while the southeast half will
only dip down into the upper 30s and lower 40s. Skies will
continue to clear overnight, but become cloudy again tomorrow mid-
morning behind a cold front that will have moved through by 12z.
Winds will turn to the north northeast at around 10 to 15 mph.
Rutt
LONG TERM...Thursday afternoon through mid next week
The main focus of the forecast remains on potential impacts from
the storm system tomorrow night. All in all, very few changes were
made to the inherited forecast as the northwest corner of our
area continues to look the snowiest.
The upper level jet is in the process of splitting and the
aforementioned strong southern stream upper level low over
southern California is reaching peak intensity this afternoon and
will soon begin to fill and weaken. This upr low will speed up and
eventually cross Colorado and Kansas tomorrow night and Fri,
briefly re-intensify, and then get ingested back into the Polar
jet over the ern CONUS this weekend. The big question for
Panhandles residents is where exactly does this low re-intensify
and how quickly does that happen. If the models are a little off
on this difficult to model process, we could be in for a more
dynamic situation with higher precip amounts (and therefore snow
totals). While an earlier and further west intensification is
possible, it does not look like the most likely scenario at this
time, and have gone with a model consensus forecast.
Unlike many snow events around these parts, snow banding doesn`t
look as likely this go around. The snow that falls will likely
accumulate in a few hours via a transient wave of briefly very
heavy snow. For this reason, current thinking is that amounts will
remain predominately in the 1-4" range, though most of it will
fall in a small time window from roughly 5PM - midnight tomorrow.
Previous thinking remains similar with the best accumulation
chances north and west of a Dalhart to Guymon line, mixed precip
between this line and US 60, and predominately rain south and east
of the US Hwy 60 corridor. Slight deviations in temperature will
shift this line, but current thinking is that impacts to Amarillo
should be minimal.
After a chilly Friday, a nice weekend rebound is in store.
Uncertainty is above normal next week as models bounce all over
the place between dry weather up to the possibility for a
significant system in the High Plains.
Simpson
&&
.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX 36 49 31 45 30 / 0 40 80 10 0
Beaver OK 33 48 27 42 22 / 10 30 70 20 0
Boise City OK 28 38 25 42 24 / 5 50 80 5 0
Borger TX 37 49 32 45 29 / 0 40 80 10 0
Boys Ranch TX 35 49 30 47 28 / 0 50 90 10 0
Canyon TX 36 51 31 46 30 / 0 50 80 10 0
Clarendon TX 40 52 35 45 29 / 10 40 80 10 0
Dalhart TX 30 43 26 45 23 / 5 50 80 5 0
Guymon OK 31 45 27 42 22 / 5 40 80 5 0
Hereford TX 36 52 32 49 30 / 0 50 80 10 0
Lipscomb TX 36 51 29 43 26 / 10 30 70 10 0
Pampa TX 36 49 31 42 28 / 5 40 80 10 0
Shamrock TX 39 54 33 46 27 / 30 30 60 10 0
Wellington TX 41 55 35 47 27 / 30 30 60 10 0
&&
.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.
&&
$$
89/99
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
850 PM CST Wed Nov 20 2019
.UPDATE...
Main change was to bump up overnight lows by a degree or two and to
adjust PoPs based on radar trends and the evening high resolution
models. Cloud cover has spread over much of the area with the
southwest flow aloft and this should act to keep temperatures mild
overnight.
Precipitation wise there are some isolated storms to the southeast of
San Angelo which should remain to the north and west of our Hill
Country counties. Lightning and Satellite data (DFX will be down
overnight, but techs are expected at the site early Thursday AM to
fix the radar) do show one isolated thunderstorm approaching the Rio
Grande just to the southwest of Del Rio. The lighting is very
sporadic with this storm and cloud top temps of -45 degrees C are
comparable with the activity to the SE of San Angelo and to the NW
of DFW. Because of this have adjusted the PoPs for now through
midnight to reflect the chance of showers and a few isolated storms
across the Rio Grande Plains. The HRRR which was showing decent
coverage across the Hill Country by early tomorrow morning has
trended drier over the last 3 runs, quickly dissipating anything that
does make it into the Rio Grande counties. Have kept slight chance
PoPs across the Hill Country and points eastward to account for an
isolated shower or weak storm that makes it into these areas by
morning, in addition to some streamer showers in the southerly flow
at the surface.
&&
.PREV DISCUSSION... /ISSUED 545 PM CST Wed Nov 20 2019/
AVIATION...
VFR flying conditions start the forecast, then MVFR CIGs redevelop
mid to late evening. Stronger low level jet will keep KSAT, KAUS,
KSSF at MVFR while weaker jet enables KDRT to fall to IFR, possibly
LIFR. Mixing rises CIGs to low end VFR in the afternoon. MVFR CIGs
redevelop Thursday evening. Have mentioned VCSH at KAUS overnight
into Thursday where the better chances of SHRA are. Should more
breaks develop in the clouds on Thursday, then TSRA are possible due
increased instability. S to SE winds 7 to 15 KTs prevail, with some
gusts to 24 KTs this evening and again on Thursday.
PREV DISCUSSION... /ISSUED 304 PM CST Wed Nov 20 2019/
SHORT TERM (Tonight through Thursday Night)...
The latest visible satellite data shows some gradual clearing of
skies ongoing for areas along and east of a Carrizo Springs to San
Antonio to Austin this afternoon. Elsewhere, some convection is noted
to our west across the Big Bend region of Texas. Afternoon
temperatures are in the 70s and 80s across south central Texas.
The main concern for this evening will be monitoring for the
possibility of some isolated thunderstorms across the far western
portion of our area, including Val Verde county. The last several
HRRR runs show some convection moving into mentioned area, as well as
portions of the southern Edwards Plateau this evening. While we can`t
completely rule this out, we have seen persistent cloud cover across
the region and this has definitely cut down on the instability. For
now, we will only maintain a very low chance (20%) for convection
across this area tonight. Elsewhere, we could also see a few showers
develop across the Hill Country and adjacent I-35 corridor overnight
as the low-level jet increases.
As for temperatures tonight, expect mild readings with most areas
only dropping into the 60s overnight. We did not include any mention
of fog tonight as it appears surface winds will remain a little
stronger than last night.
Mild temperatures are in store Thursday, with highs mainly in the
70s and lows in the 60s. With a fairly active southwest flow aloft
over the region, we will also maintain a low chance for showers and
storms for the Hill Country, most of the I-35 corridor and coastal
plains during the daytime. Rain chances spread across most of the
remainder of south central Texas Thursday night with continued
southwest flow aloft.
LONG TERM (Friday through Wednesday)...
A cold front will move into south central Texas early Friday morning,
reaching the far northern portion of the Hill country and the
southern Edwards Plateau around sunrise. The cold front will make
steady southward progress through the morning and afternoon hours
with scattered showers and a few thunderstorms developing along the
frontal boundary. Severe storms are not anticipated with this front
as it appears the stronger forcing will remain across north Texas.
Given the better lift will be farther north of our region, we should
only see a broken line of convection develop along and north of a
Kerrville to San Antonio to Karnes City line. Rainfall amounts are
not overly impressive across our region, with amounts generally
expected to remain in the 1/4" or less range.
A quick end to precipitation chances is in store Friday evening, with
only a very low chance expected along the Highway 77 corridor through
the mid-evening hours. Cooler temperatures are in store Friday
night, with lows dropping into the upper 30s in the Hill Country to
near 50 along the Rio Grande plains.
A quiet weather pattern is anticipated for the upcoming weekend as an
upper level system moves east of the region, leaving stable west to
northwest flow aloft over our region. We do expect another weak surge
of surface high pressure to move in on Saturday, but little notable
cooling is expected behind this Pacific cold front.
Low-level southerly flow returns to the area by early Monday morning
as the next weather system to impact our region moves through the
Pacific northwest. There is some model uncertainty with respect to
how quickly this system moves eastward across the Rockies into the
southern U.S. plains. We do expect a cold front to move through on
Tuesday, but the timing of the front remains highly uncertain. A peak
at the latest 12Z ECMWF shows the timing has trended toward the
slower 12Z GFS, which would bring the front through Tuesday night as
opposed to Tuesday morning. For now, we will keep rain chances
fairly low and confined to areas generally along and east of the I-35
corridor. Significant cooling is not anticipated behind this front
and it appears overnight lows over the next 7 days will likely not
drop below freezing across south central Texas.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 67 77 63 70 45 / 20 30 30 50 10
Austin Bergstrom Intl Airport 67 78 62 72 43 / 20 30 30 50 10
New Braunfels Muni Airport 66 78 62 73 45 / 20 20 20 40 10
Burnet Muni Airport 65 75 58 65 41 / 20 30 50 50 -
Del Rio Intl Airport 63 80 61 76 48 / 20 - 20 0 0
Georgetown Muni Airport 67 76 60 68 42 / 20 30 40 50 10
Hondo Muni Airport 66 80 62 77 46 / 10 10 30 20 0
San Marcos Muni Airport 66 78 62 72 44 / 20 20 30 40 10
La Grange - Fayette Regional 68 79 65 75 45 / 20 30 20 50 20
San Antonio Intl Airport 67 78 64 73 47 / 10 20 20 30 -
Stinson Muni Airport 67 78 64 74 48 / 10 10 20 30 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Aviation...04
Short-Term/Long-Term...Treadway
Area Forecast Discussion
National Weather Service Grand Forks ND
947 PM CST Wed Nov 20 2019
.UPDATE...
Issued at 941 PM CST Wed Nov 20 2019
Headlines have expired along and west of the valley as snowfall
continues to track east. Best snowfall rates currently depicted
from western Polk into Clearwater and Beltrami counties where the
winter weather advisory continues until 3am. Also seeing a few
SFC observations in the northern valley of 2 to 5 mile visibility
with FZDZ potential as saturated lower layer exists with ice
nuclei aloft exiting east with the stronger forcing. Went ahead
and added this to the forecast for an hour or two following the
departing snow system.
UPDATE Issued at 605 PM CST Wed Nov 20 2019
Narrow band of thunder developed around 430pm and is lifting
northeast into colder air turning into efficient snow showers. As
this area of conditional instability moves into the area north of
Park Rapids towards Bemidji snowfall rates up to an inch an hour
could persist for the next 2 to 4 hours. So expanded the advisory
to include southern Clearwater and Hubbard. To the west snowfall
has ended and let the advisory at Towner expire at 6pm.
Visibilities are generally ranging from 1 to 4 miles as snowfall
rates have tapered off some late this afternoon and evening.
Impacts from snow covered roads are causing slow downs and both ND
and MN DOT are reporting vehicle spin outs.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 304 PM CST Wed Nov 20 2019
Additional snow amounts tonight will be the main issue for the
period.
Lead shortwave is currently pushing through the Northern Plains
with low pressure to our south. There continues to be strong 700
mb frontogenesis across portions of the Devils Lake Basin into
northern Red River Valley. There have been some reports of 5-6
inches over Nelson county, and the RAP has the very strong
frontogenesis hanging around that region for another hour or two
before shifting to the east. With snow rates of an inch per hour
continuing a bit longer, and a new band developing slightly west,
think there could be warning criteria snow from Nelson county into
western Walsh and eastern Ramsey counties, even up into Cavalier
county. Will be putting out a small winter storm warning for that
area, and will monitor the band as it moves east. There are some
signs that frontogenesis will weaken later tonight as it moves
into northwestern MN, so will limit the eastward extent of over 6
inches of snow.
The main northern branch shortwave will head eastward tonight,
with some fairly strong cold air advection behind it. Snow will be
tapering off, but there will be some gusty winds tonight
especially over the southern Red River Valley. Have some patchy
blowing snow mention but still seems that the worst winds will be
south of where the heavier snow fell. Temperatures will be falling
quickly too, and areas that see rain this afternoon could freeze
pretty quickly overnight. Temps in the teens to 20s overnight will
not rise much on Thursday, only into the low to mid 20s as cold
surface high pressure settles into the region.
.LONG TERM...(Thursday night through Wednesday)
Issued at 304 PM CST Wed Nov 20 2019
Thursday night...Quiet and cold with northwest flow aloft and high
pressure. The center of the high will be just to our south, so
winds will not be completely calm. However, with a cold air mass,
at least some clearing, and fresh snow, lows will drop below the
10 mark in northwestern MN with teens elsewhere.
For Friday through the weekend, benign weather and seasonal
temperatures will prevail with daytime highs in the 30s to lower 40s
and overnight lows in the 20s. During this period, the Northern
Plains remains under the influence of the northern stream of split
flow regime with longwave ridging aloft prevailing over the western
half of the CONUS. Northwest flow aloft and a persistent closed low
over the Hudson Bay looks to track any upper level disturbances
north of the international border, keeping impactful weather at bay
through at least early Sunday.
Warmer air builds in briefly on Sunday, yielding breezy west winds
and high temperatures in the mid 30s to mid 40s. This comes with
warm air advection in advance of a clipper system trekking southeast
across the Canadian Prairie. At this point, there is low confidence
in the exact track of this system and associated temperature fields,
but probabilistic guidance suggests snow would be the most likely
precipitation type associated with precipitation chances Sunday and
Monday. Additionally there is good agreement that the upper low will
continue to mature and stall out over northeast MB on Monday,
prompting colder air to dig into the region Tuesday and dropping
daytime high temperatures below the freezing mark for the middle to
end of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 605 PM CST Wed Nov 20 2019
Snow ending west to east this late this evening. IFR CIGs will
give way to VFR conditions by morning. Winds will become gusting
from the north at FAR overnight.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...Winter Weather Advisory until 3 AM CST Thursday for MNZ005-006-
008-009-013>017-023-024.
&&
$$
UPDATE...JK
SHORT TERM...JR
LONG TERM...BP
AVIATION...JK
Area Forecast Discussion
National Weather Service Wichita KS
841 PM CST Wed Nov 20 2019
.UPDATE...
Issued at 841 PM CST Wed Nov 20 2019
Mid-level dry slot has resulted in a quicker demise to the showers
across all but southeast Kansas at mid-evening. While the NAM/RAP
may be a bit too bullish on pocket of elevated instability, its
depiction along with the HRRR of showers perhaps with thunder
developing along the cold front as it moves across central Kansas
and eastern Kansas seems plausible overnight. Have updated PoPs
to reflect this trend after the current lull across central
Kansas, though modest redeveloping PoPs will be rather progressive
with the frontal movement overnight for locations west of the
turnpike.
KED
&&
.SHORT TERM...(This evening through Friday)
Issued at 344 PM CST Wed Nov 20 2019
Highlights:
1) Showers & a few thunderstorms
2) Cool down Thu
3) Possible wintry mix & snow Thu night - Fri
Headline: Wind Advisory until 6PM
Challenge: precipitation chances and type for Thu night - Fri
Changes: chance and slight timing adjustments to precipitation
A trough remains positioned from Hudson Bay to southern California
with a wave moving across the Front Range into the Central Plains.
The northern portion of the trough combines with the wave to bring a
cold frontal boundary through this evening and tonight. A tightened
gradient and mixing have led to gusty winds this morning and
afternoon which did prompt the issuance of a Wind Advisory. There
are many sites especially in southeast Kansas which are marginal and
below criteria, but the advisory only goes until 6PM and may even be
able to be cancelled an hour or so early.
Showers and thunderstorms have developed with most of the storms in
southwest Oklahoma into Texas. As highlighted in the previous
discussion, roughly 500 J/kg of MUCAPE works its way into the
central and eastern portions of Kansas this evening and tonight.
Thus there is the potential for a few thunderstorms. Please see the
mesoscale discussion for further details on the late afternoon and
evening set up.
Chances of precipitation exit by mid morning on Thursday with a
break until the evening hours when another wave moves across. Cold
air advection comes in behind the front dropping temperatures
especially in the central and south central portions of the state by
10-20 degrees. The cooler air means a change in the precipitation
type, but there is still the question of the level of moisture
within the dendritic or ice crystal growth zone primarily in south
central Kansas. Model soundings vary on this depth of moisture and
presence within the dendritic growth zone thus it is a challenge to
know which one is correct. Some adjustments were made to the
probability of ice and respective precipitation type grid given the
lower confidence. In central Kansas, there could be minor snowfall
accumulations initially, but it is not expected to last very long
with a wet ground and soil temperatures in the 50s.
A reinforcing shot of cold air moves in with the next wave to keep
high temperatures on Friday only around 40 degrees. Only lingering
and slight chances of precipitation are anticipated to maybe take
off some of the less pleasant factor. At least the winds should only
be around 5 to 10 mph.
.LONG TERM...(Sunday through Wednesday)
Issued at 344 PM CST Wed Nov 20 2019
Highlights:
1) Warm up Sat - Mon
2) Potential system Tue - next Wed
The southern portion of the mid and upper level trough is expected
to move east across the Central Plains on Saturday. There will be
little influence with this system as it has weakened by that point.
A gradual warming trend should occur for Saturday thru Monday.
Another system is anticipated to move through Tuesday and next
Wednesday, but the models remain quite divergent. The GFS is quite
aggressive with a wrapped up system which could certainly create
travel concerns if its resolution pans out; however, the ECMWF does
not show the same. It is really anyone`s guess at what will occur.
Confidence is low on the current precipitation chances that are in
the forecast, and changes are guaranteed for this time period.
Temperatures could swing in either direction as well with the
GFS ramping cold air advection for Tuesday. Stay tuned.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 542 PM CST Wed Nov 20 2019
IFR/MVFR cigs and vsbys in stratus/rain showers will prevail ahead
of a cold front this evening/tonight. While a period of MVFR cigs
may linger just behind the cold frontal passage, conditions are
expected to improve to VFR late tonight into Thursday morning.
Gusty south winds will become gusty north-northwest winds behind
the front. A period of LLWS is expected just ahead of the front.
KED
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 43 52 31 41 / 60 0 40 20
Hutchinson 40 50 27 40 / 50 0 40 20
Newton 41 50 28 40 / 60 0 40 20
ElDorado 44 52 31 41 / 80 10 50 20
Winfield-KWLD 48 54 33 43 / 80 10 40 20
Russell 35 45 25 39 / 50 0 40 20
Great Bend 36 47 25 38 / 40 0 40 20
Salina 39 48 27 40 / 60 0 30 20
McPherson 39 48 26 39 / 50 0 40 20
Coffeyville 55 61 35 44 / 90 30 50 20
Chanute 54 57 34 43 / 90 20 40 20
Iola 53 56 33 42 / 90 20 30 20
Parsons-KPPF 55 59 35 43 / 90 30 50 20
&&
.ICT WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...KED
SHORT TERM...VJP
LONG TERM...VJP
AVIATION...KED
Area Forecast Discussion
National Weather Service Marquette MI
651 PM EST Wed Nov 20 2019
.SHORT TERM...(This evening through Thursday)
Issued at 354 PM EST WED NOV 20 2019
WV imagery and RAP analysis indicated a mid/upper level trough from
north central Canada to a low over southern CA and a ridge through
the Mississippi Valley. A vigorous upstream shortwave was lifting
northeast from southeast CO. At the surface, a trough extended
northeast from low pressure over western KS while ridging prevailed
from the Ohio Valley into the central Great Lakes. Radar indicated
weak reflectivities from ne Mn into western Upper Michigan, with
mainly virga except over the Arrowhead. Temps over most of Upper
Michigan and northwest WI have climbed to around 40 under mostly
cloudy skies with weak WAA.
Tonight, expect precipitation to increase overnight as
WAA/isentropic lift increases ahead of the CO low and shrrtwv.
Forecast soundings suggest that the warm layer will prominent enough
for rain over Upper Michigan. Since temps have started out higher
today and should only dip into the mid 30s when the rain starts,
icing is not expected. However, some locally icy spots may be
possible if temps drop off farther in some isold locations.
Thursday, as the trough slides east of the area early, CAA with
quickly falling temps will change the rain over to snow in the west
around 12Z. Strong 850-700 mb fgen/deformation will support a brief
period of heavier snow over the west. The synoptic support combined
with strong northerly winds and 850 mb temps dropping (from -3C to -
6C in the morning to -10C in the afternoon) will also result in
lake and terrain enhancement. Although QPF values to around 0.40-
0.50 inch are expected, low SLR values at or below 10/1 should keep
overall accumulations in the 3 to 5 inch range from IWD to P59 and
into Baraga county.. As the rain changes to snow over the rest of
the area in the afternoon, smaller snow amounts of around an inch
will be possible over Marquette and Iron counties.
.LONG TERM...(Thursday night through Wednesday)
Issued at 341 PM EST WED NOV 20 2019
Lingering lake-effect snow Thursday night into Friday morning will
taper off from west to east as large-scale subsidence increases with
surface ridging working into the region. This will start a period of
quieter weather for Upper Michigan. Outside of a few small chances
for some wintry precipitation on Sunday, the weather is expected to
remain relatively quiet. Daytime highs will be close to normal, in
the 30s, with overnight lows falling into the 20s. Overall, nothing
out of the ordinary for this time of year.
As mentioned in previous discussions, model solutions continue to
struggle with the early/middle parts of next week. Unfortunately,
this time period also overlaps with a busy Thanksgiving Holiday
travel week. Given we`re still looking 5-7 days out at this point,
there is plenty of change that will occur within the forecast as we
get closer and the details become refined. Therefore, we encourage
everyone to stay updated on the latest forecast as we continue to
get closer. Now, onto what we know...there will be two different
waves that impact the Upper Great Lakes early/middle next week. The
first wave looks to impact the region Monday/Tuesday, but looks much
weaker, compared to the second wave. Right now have opted to leave
NBM PoPs in for the Monday/Tuesday time frame, which shows a chance
for widespread snow (esp. by Tuesday). However, with this first wave
digging south from Canada, it may be difficult to get decent
moisture our way. Therefore, it is possible the forecast for early
next week could trend drier. This first wave of energy does look to
remain just north of the border in Canada, and could lead to further
amplification of the secondary, stronger wave expected to lift
northeast from the Plains Tuesday night/Wednesday. This secondary
wave will have the potential to bring with it some better moisture
from the Gulf of Mexico, depending on where the system tracks.
That being said, there are major differences between model solutions
that far out. To highlight just how much uncertainty there is with
this secondary wave, below are a few scenarios that *could* play out
based on current model guidance.
- The GFS paints by far the worst-case scenario for the Upper
Peninsula, with the main surface low deepening as it lifts across
central Wisconsin and eastern Upper Michigan. This would favor the
*potential* for system snow across the west transiting over to rain
across the east, then transitioning over to all snow on the backside
of the system as it exits. This storm track would favor lake-
enhancement precipitation off of Lake Superior for some spots. The
track and strength of this surface low would also favor strong winds
over Lake Superior, which would favor higher waves and the potential
for some lakeshore flooding concerns. Again, this appears to be the
worst-case scenario when taking a look at the suite of medium-range
deterministic guidance.
- The Canadian is a bit slower with the wave and thus further south,
and far weaker with the overall magnitude of deepening the surface
low undergoes. This solution still favors some of eastern Upper
Michigan being clipped by some snow, but overall colder air wrapping
around favoring some light lake-effect precipitation across the west
and wrapping in behind the departing low.
- The ECMWF is even slower and further south compared to the GFS and
Canadian, with no system precipitation making it this far north. In
fact, the only precipitation looks to be primarily lake-driven, with
lake-effect snow in the Lake Superior snowbelts.
Ensembles means tend to support the surface low tracking somewhere
across the Upper Great Lakes, with the mean surface fields bringing
the low pressure center across central or eastern parts of Upper
Michigan. Based on current model trends continuing to jump around in
their solutions, the ensemble approach seems to be best in this case
so didn`t make any changes to the NBM PoPs for Tuesday
night/Wednesday. Of course, nothing is set in stone, but as you can
see from the scenarios described above, there is still a lot of room
for changes in the forecast. This applies not only to the Upper
Peninsula, but the region in general. Will definitely need to keep
an eye of model trends as we progress through the weekend into early
next week to get a better handle on if there will be any potential
for the mid-week storm system to impact Thanksgiving holiday travel.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 651 PM EST WED NOV 20 2019
As low pres organizing over the Plains tonight lifts ne toward the
Great Lakes, expect deteriorating conditions overnight at
KIWD/KCMX/KSAW as rain spreads into the area. VFR conditions or high
MVFR cigs this evening will fall to LIFR late tonight at all
terminals. During Thu morning, conditions will remain LIFR at all
terminals as rain changes to snow by mid morning at KIWD/KCMX and
mixes with snow at KSAW late morning/early aftn. NNW winds will
become gusty to 20-30kt during the day. In the aftn, expect
improvement to MVFR at KIWD/KSAW and to IFR at KCMX.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 354 PM EST WED NOV 20 2019
Winds will back from the SW to SE tonight as a low approached Lake
Superior from the Central Plains. As the low moves east of the lake
on Thursday morning, winds back to the N-NW increasing in speed as
the pressure falls and the gradient increases. By Thursday afternoon
winds across all of the lake will be N to NW with gusts up to 40
knots. A gale watch remained in effect across the eastern half of
Lake Superior starting Thursday afternoon through late Thursday
night. Waves are expected to build up to 13 feet across eastern Lake
Superior Thursday night. Winds will relax to around 20 knots by
Friday afternoon before increasing from the W up to 30 knots Friday
night into Saturday morning as a trough approaches the lake from the
NW in Canada. Winds will then relax below 20 knots Saturday
afternoon through Tuesday morning. There is a chance for another low
pressure system to develop and cross Lake Superior Wednesday evening
through Thursday, but strength and track of the low remain
uncertain.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory from 7 AM EST /6 AM CST/ to 7 PM EST /6
PM CST/ Thursday for MIZ001>004-009-084.
Lake Superior...
Gale Watch from Thursday evening through late Thursday night for
LSZ251-267.
Gale Watch from Thursday afternoon through late Thursday night
for LSZ249-250-266.
Gale Watch from Thursday afternoon through late Thursday night
for LSZ244-245-248-264-265.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Ritzman
AVIATION...Rolfson
MARINE...JLB
For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php
Area Forecast Discussion
National Weather Service Tulsa OK
851 PM CST Wed Nov 20 2019
...UPDATE...
.DISCUSSION...
Progressive upper wave is currently pushing into
western/central OK, with showers shifting quickly
east across the region this evening. Based on radar
trends and recent HRRR runs, have lowered PoPs from
late evening through most of the remainder of the
night. Could see some redevelopment late tonight or
early Thursday morning along the cold front as it
enters northeast OK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 60 63 37 45 / 80 40 80 50
FSM 61 67 47 53 / 40 80 100 80
MLC 64 69 40 48 / 50 80 100 70
BVO 54 58 35 44 / 90 30 70 40
FYV 60 67 40 47 / 60 80 100 70
BYV 58 68 39 47 / 50 70 100 70
MKO 62 67 39 46 / 60 70 90 60
MIO 58 63 35 43 / 80 40 70 40
F10 62 67 38 45 / 60 70 90 60
HHW 64 69 48 52 / 40 80 100 90
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...18