Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/17/22
Area Forecast Discussion
National Weather Service La Crosse WI
625 PM CDT Sun Oct 16 2022
.DISCUSSION...(This evening through Sunday)
Issued at 250 PM CDT Sun Oct 16 2022
Key Messages:
- Anomalously cold air mass moving in with wind chills in the teens
by morning. Prepare for these unusual cold temperatures.
- A tale of extremes this week...Well below normal temperatures
to start the week and well above normal temperatures to end
the week
- Still mainly dry through Saturday...some potential for rain by
Sunday
Through Monday:
Numerous showers today in WI, giving way to near-record cold
temperatures and wind chills by morning. The dominance of the deep
large scale trough over Great Lakes will increase through Monday
with the heart of the coldest air coming in. Cold advection is
ongoing with temperatures not warming much from morning lows
(~3F). GOES water vapor with RAP tropopause mapping shows a
vigorous shortwave trough near Minneapolis with moderate lift now
over the area. Showers have blossomed and continue to develop and
increase in coverage as steep lapse rates and minor MUCape (~100
J/Kg) is released. More stability and shallower moisture westward
is causing a sharp cutoff to the showers on about the Miss River.
As the trop fold passes overhead and shifts east, and with
nightfall, showers are expected to decrease in coverage but still
be around this evening. These may change to snow as well but no
accumulation is expected. The steep lapse rates will continue to
harvest a moderately strong wind field for gusts overnight in the
20-30 mph range in the mixed layer.
Overnight lows are tricky with consensus in the CAMs and national
blend suggesting dewpoints will crash into the teens for most of the
area. Recently, observations are showing dewpoints falling into the
18-22F range in the eastern Dakotas and western MN making this
scenario a bit more plausible. Highest confidence is in WI remaining
cloudy overnight and latest GOES visible imagery suggests a cellular
nature to the clouds in MN/IA, suggesting some clearing is quite
possible overnight on the western flank. This will aid in getting
colder. Have warmed the WI areas a few degrees from previous
forecast for overnight lows. The main impact weather of the week is
the combination of winds and temperatures Mon/Tue mornings...VERY
unusual to have wind chills in the teens...and that is without the
wind gusts factored in. Have already hit this in social media but
will continue to increase the message for preparedness for
those mornings.
Extended Overview:
The broad trough of 500mb low pressure covers much of the Upper
Mississippi Valley/Great Lakes south to the South Atlantic States
eastward. Anomalously cold temperatures continue through mid-week
as the low gradually migrates eastward. Wednesday through
Sunday...a ridge over the Rockies and a more westerly flow aloft
allows warmer temperatures to return across the Plains. The next
potential weather-maker moves into the Pacific Northwest Saturday.
There is a spread in if the 500mb heights will amplify or remain
more zonal affecting temperatures for the weekend and the strength
of moisture return Sunday.
Monday Night through Wednesday Morning:
The NAEFs anomalies continue to show that 850mb temperatures are
2 standard deviations below normal with winds 2 to 3 standard
deviations above normal and specific humidity 1 to 2 standard
deviations above normal. This leads to blustery conditions Tuesday
with cold wind chills in the single digits and teens Tuesday and
teens Wednesday mornings. Still dry with highs in the upper 30s to
mid 40s Tuesday with 40s for Wednesday. The record low at
Rochester Tuesday the 18th is 17, and we have a near record low of
20 forecast. Precipitable water values remain very low...only
0.2" to 0.4".
Wednesday Afternoon Through Sunday:
The winds will not be quite as strong Wednesday, however look for
west winds to gust at times 10 to 20 mph. Moderating highs in the
40s are on tap for Wednesday with highs in the 50s Thursday.
Southwest winds increase for Friday, thus we have much
warmer...above normal temperatures in the 60s expected. These
warmer temperatures continue for Saturday/Sunday, where 60s and a
few 70s return. Depending on how the storm system evolves for
Sunday, we could see the chance for showers/thunderstorms. Some of
the GEFs ensembles return precipitable water values back to above
1" by then.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 624 PM CDT Sun Oct 16 2022
Scattered showers will continue to move through KLSE through
17.02z. These showers will likely not impact visibilities.
Cyclonic flow aloft will keep a broken 4-6K deck of clouds at the
TAF sites through Monday. In addition to these clouds, the
northwest winds will remain gusty in the 15 to 25 knot range.
&&
.CLIMATE...Record Cold Highs Possible Monday
Issued at 624 PM CDT Sun Oct 16 2022
It continues to look like some record cold high temperatures may
be tied or broken on Monday. Here are some of the cold high
records for October 17.
Austin MN 38F in 1948
Charles City IA 33F in 1930
Decorah IA 35F in 1930
La Crosse WI 35F in 1930 and 1880
Mauston WI 43F in 2004
Medford WI 34F in 1930
Oelwein IA 37F in 1930
Prairie du Chien WI 43F in 1909
Preston MN 41F in 2004
Rochester MN 35F in 2004 and 1976
Sparta WI 41F in 2004 and 1976
Viroqua WI 36F in 1930
Winona MN 38F in 1976
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Baumgardt/Zapotocny
AVIATION...Boyne
CLIMATE...Boyne
Area Forecast Discussion
National Weather Service Charleston SC
1024 PM EDT Sun Oct 16 2022
.SYNOPSIS...
High pressure over the area will move offshore tonight. A
strong cold front will move through the region Monday night,
followed by cool high pressure into next weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Late this evening: All is quiet as weak high pressure prevails
ahead of an approaching cold front. Aloft, the flow will remain
nearly zonal with a bit of cyclonic curvature thanks to the deep
upper low centered across the Great Lakes. The upstream front
will draw closer overnight, moving just into the lee of the
Southern Appalachians around or just after sunrise Monday. This
setup will drive southwesterly flow across the forecast area,
and there could be just enough low-level convergence to kick off
an isolated shower or two. However, model soundings are quite
dry through the mid-levels, so no measurable rainfall is
expected across land areas. More bonafide showers will be
possible across the coastal waters, but whatever develops will
be weak at best. We will see a steady stream of mostly high
clouds in the westerly flow aloft, which will help lows from
getting too low. Upper 50s to low 60s should be common.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Synopsis/Forecast: Highly amplified Omega blocking pattern
persists across the CONUS with sharp N-S ridging through the
Rockies, anchored by troughing over the eastern Pacific and
anomalously deep troughing/cold air across eastern NOAM.
Prominent short-wave energy and reinforcing shot of cold air is
diving down through the upper Midwest today and will close off
another deep upper low over the Great Lakes through at least the
first half of this week. This will drive a cold front down
through the coastal Carolinas and SE Georgia Monday
afternoon/Monday night while anomalously cold H8 air (10-15 C
below normal) overspreads most the the eastern CONUS...all the
way into northern Florida.
Details:
Aforementioned surface cold front will be advancing down
through the western Carolinas/northern Georgia region Monday
morning with quiet weather hanging on here...although with
increasing cloud cover out ahead of the boundary. Boundary
continues to slip into and through our area later Monday
afternoon through Monday evening and out into the Atlantic by
Tuesday morning. Interestingly, guidance remains quite stingy
with precip chances/QPF across the CWA as the front presses
through, possibly the result of some drier low level air seen in
forecast soundings. But given moisture advection ahead of and
along the boundary, some potential destabilization (500-1000
J/Kg MLCAPE Monday afternoon per HRRR guidance) and low level
convergence with the front...will hang on to at least isolated
to scattered pops Monday afternoon through Monday evening. Given
strong mid- level westerly flow developing across the region
and 0-6 Km bulk shear values in excess of 40 knots, if we can
get some convection to develop, some stronger storms still
cannot be ruled out, and the SPC Day 2 outlook maintains a thin
marginal risk across the coastal counties.
Behind the boundary, much cooler and drier air overspreads the
region starting Tuesday, setting up a quieter/cooler stretch of
weather. Clearing skies by Tuesday night might allow for decent
radiational cooling conditions, although we do hang on to some
boundary layer wind throughout the night that may curtail the
temperature drop and frost possibilities. Will continue to
advertise patchy frost across our cold spots (well inland west
of the I-95 corridor) with lows in the middle to upper 30s.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Surface high pressure will reassert itself through the long-
term period and bring another stretch of quiet weather. Large
expanse of anomalously cold air will continue rotate through
most of the eastern CONUS through at least early Thursday before
gradually undergoing modification and retreating to the
north/east.
Temperatures will continue to run below normal through the
latter half of the week, particularly overnight lows. And with
weakening winds/clear skies, the coldest overnight/early morning
temps (and best candidate for frost headlines) will likely
occur Wednesday night/Thursday morning with solid middle to
upper 30s anticipated inland. Will maintain patchy to areas of
frost across those inland areas at this juncture and continue to
highlight the frost potential in the Hazardous Weather Outlook.
Temperatures rebound to around seasonal norms through next
weekend. Quiet weather overall. But with that said, longer term
model guidance hint at the development of some troughiness in
the coastal waters next weekend...which might eventually present
some forecast challenges. 12Z Euro has turned very bullish with
the development of a stronger coastal system pressing into our
area next weekend, which is most certainly an outlier within the
envelope of guidance. But something to keep an eye on.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
VFR conditions will prevail at KCHS, KJZI, and KSAV through 00z
Tuesday. Southwesterly winds could get a little gusty on Monday,
with gusts into the 15-20 knot range mostly in the afternoon.
Also, isolated showers and thunderstorms could develop in the
late afternoon and early evening. As of now confidence is low in
any direct impacts to the terminals.
Extended Aviation Outlook: Isolated showers and thunderstorms
are possible late Monday afternoon and Monday evening as a cold
front moves through the region. Some brief flight restrictions
are possible with any precip that moves over a terminal. After
FROPA, high pressure builds across the region for the rest of
the week and will bring solid VFR conditions.
&&
.MARINE...
Tonight: South winds this evening will veer to the southwest
and increase to 10-15 kt overnight, with 15-20 kt possible at
times. Seas 1-2 ft will build to 2-3 ft by daybreak Monday.
Monday through Friday: Southwest winds will increase in the
coastal waters on Monday...ahead of a cold front that will move
across the waters Monday night. Some gusts on Monday may touch
Small Craft Advisory criteria although seas will remain well
below criteria. Small Craft Advisory headlines may eventually be
needed, but no headlines are planned at this juncture.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...BSH
SHORT TERM...TBA
LONG TERM...TBA
AVIATION...BSH/TBA
MARINE...TBA
Area Forecast Discussion
National Weather Service State College PA
1015 PM EDT Sun Oct 16 2022
.SYNOPSIS...
Following a seasonably warm and pleasant end to the weekend,
the coldest air so far this season will bring below normal
temperatures to central Pennsylvania through late week. The
cold air may also deliver the first snow accumulation to parts
of northwest Pennsylvania. Dry weather and moderating
temperatures are forecast Friday through next weekend.
&&
.NEAR TERM /THROUGH MONDAY/...
Surging low level moisture ahead of a weak surface low across
southeast Pa, combined with falling heights, has supported a
lone thunderstorm late this evening over southern York County.
Based on latest RAP and radar trends, will maintain the chance
of a shower or thunderstorm across portions of York/Lancaster
County through around 06Z. Focus then shifts to digging trough
approaching from the Grt Lks. The associated occluded front is
progged to push through central Pa between 09Z-18Z. Limited
moisture should result in only widely scattered showers with the
fropa, with better large scale forcing resulting in the best
chance of measurable rain over the northwest mountains early
Monday morning.
Dry slot is progged to work into the region behind the front
Monday. However, cold temps aloft and meager diurnal heating should
result in a fair amount of cu/stratocu over the Alleghenies
with a stray afternoon shower possible.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
Anomalous (-2 to -3SD) 500mb trough carving out along the
Appalachians will deliver the coldest air so far this season to
CPA early this week. Max temps drop 5-15F each day with fcst
highs -10 to -20F below climo by Tuesday in the upper 30s to
near 50F. It will be breezy which will make it feel even colder
(20s-30s) over the western Alleghenies.
A freeze watch was issued Monday night with highest confidence
of subfreezing temps over the Laurel Highlands. Refer to climo
section for updates on counties no longer active in the growing
season.
Bulk of light precip will be confined along the western
elevations (<0.10 fcst east of US219) with max QPF closer to
the Lake Erie shoreline given mean WSW flow. Temps sfc and
aloft cold enough to support lake enhanced/orographic rain to
snow shower transition Monday night into early Tuesday morning
and again Tuesday night. The first snow accumulation (1-3") is
most likely in the favored lake effect belt particularly in NW
Warren County.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Not too many changes to the long-term forecast with today`s
update. Still looking at the deep trough/cut-off low to bring
anomalously cold temperatures for the early and middle part of
the week. Shortwaves rotating through the trough will produce
lake-effect snow and rain showers over far northwestern
Pennsylvania into Wednesday night. Some flurries may even make
it as far east and central Pennsylvania on Wednesday.
The upper-level low starts to pull away on Thursday. Aside from
occasional sprinkles/flurries in far northwestern PA, Thursday
should be a mainly dry day across PA.
All medium range guidance supports dry and warmer weather into
next weekend, as upper level ridge over the Atlantic retrogrades
westward to the east coast. Model 925mb temps support highs well into
the 60s by next Saturday/Sunday. The 12Z ECMWF suggests rain is
possible next Sunday night associated with a cut off low
drifting northward along the east coast. However, the bulk of
guidance, including the ECENS, indicate dry weather is likely
through Sunday night.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
VFR conditions under a high BKN-OVC will continue into the
overnight hours. Wind will also be light overnight.
Clouds will increase/thicken overnight as a frontal system
approaches from the west. Scattered light rain showers are
possible across the NW, perhaps as early as the predawn hours
Mon, but most showers will hold off until after sunrise.
A brief period of MVFR conditions is also possible around
sunrise in the Lower Susq.
Post-front by midday Mon, west winds will pick up with speeds
around 10-12kts gusting to 20-25kts, before diminishing into Mon
eve.
Outlook...
Mon night-Wed...Colder with a breezy SW-W flow and daytime
rain/ nighttime snow showers across N/W PA.
Thu...Slight chance of a lingering shower NW, otherwise mainly
VFR.
Fri...No sig wx.
&&
.CLIMATE...
Based on a collection of observations from a variety of sources
that indicated widespread freezing conditions, we have ended
the growing season for Warren County. The growing season was
ended for Potter, Elk, and McKean Counties on October 9th.
&&
.EQUIPMENT...
Scheduled maintenance on many regional ASOS sites will occur
over the next few weeks. Interruptions to mainly the wind
sensor data, but, at times, much of the observation data, can
be expected to be impacted/unavailable.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Freeze Watch from late Monday night through Tuesday morning
for PAZ011-012-017>019-024>027-033>035-037-041-042-045-046.
&&
$$
SYNOPSIS...Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Steinbugl
LONG TERM...Fitzgerald/Buvala
AVIATION...RXR/Tyburski
CLIMATE...
EQUIPMENT...
Area Forecast Discussion
National Weather Service Dodge City KS
537 PM CDT Sun Oct 16 2022
...Updated Aviation Discussion...
.SHORT TERM...(This evening through Monday)
Issued at 1200 PM CDT Sun Oct 16 2022
Tranquil conditions will persist tonight into Monday as ridging
aloft continues to build while shifting slowly east through the
northern Intermountain West. Any precip chances are expected to
remain confined well to our south in association with a closed upper
low tracking east through the Desert Southwest. A colder air mass
settling across the Western High Plains will be reinforced tonight
by surface high pressure sliding east-southeast through the Upper
Midwest and Central Plains, further dropping H85 temperatures closer
to 0C in central Kansas. Depending on how long ongoing cloud cover
lasts into tonight, we could see lows dipping near to a little below
freezing across northern zones, particularly up near the I-70 corridor.
Otherwise, lows mainly in the 30s(F) are to be expected by early
Monday morning. For Monday, should see afternoon highs generally
up into the 60s(F) with temperatures potentially struggling to
climb out of the 50s(F) in central Kansas.
.LONG TERM...(Monday night through Sunday)
Issued at 1252 PM CDT Sun Oct 16 2022
A prevailing dry pattern will continue through the end of the week
as amplified ridging aloft across much of the Intermountain West
Tuesday begins to slowly break down, giving way to a more zonal flow
aloft by the weekend. Little change in temperatures is expected from
Monday into Tuesday with surface high pressure slow to extend farther
southeast through the Central Plains. Expect highs Tuesday generally
up into the 50s/60s(F). A warming trend is then projected to take
place through the end of the week as the aforementioned upper level
ridging breaks down as it edges into the Western High Plains. Highs
reaching the 70s(F) can be expected Wednesday and Thursday with
temperatures pushing well above normal Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 533 PM CDT Sun Oct 16 2022
VFR conditions expected for all TAF sites the entirety of the
period. Light northwest winds 8-10kts and mainly clear skies.
Patchy fog will develop for all but LBL between 09-13Z but with
uncertainty of coverage, only dropped visibility to 5SM at this
time with HRRR short term models indicating the lowest to be
towards the Colorado state line and into eastern Colorado itself.
Otherwise, expect clear skies and light northeast winds after 13Z
for the remainder of the period with no other weather elements
expected at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 32 61 30 56 / 0 0 0 0
GCK 31 63 29 58 / 0 0 0 0
EHA 37 64 34 63 / 10 0 0 0
LBL 35 64 32 60 / 0 0 0 0
HYS 31 58 27 51 / 0 0 0 0
P28 38 62 31 55 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 1 AM to 10 AM CDT Monday for KSZ030-031-
043>046-061>064.
Freeze Warning from 1 AM to 10 AM CDT Tuesday for KSZ030-031-045-
046-065-066.
Freeze Watch from late Monday night through Tuesday morning for
KSZ064-078>081-088>090.
&&
$$
SHORT TERM...JJohnson
LONG TERM...JJohnson
AVIATION...Lowe
Area Forecast Discussion
National Weather Service Miami FL
724 PM EDT Sun Oct 16 2022
...New AVIATION...
.SHORT TERM...
(Rest of today through Monday)
Issued at 256 PM EDT Sun Oct 16 2022
Latest RAP and surface analysis shows high pressure off the SE coast
and whats left of a weakening frontal boundary across the straits of
Florida. There is also a frontal boundary that stretches from the SW
US through the deep south, and then NE up towards the Great Lakes
region, with multiple areas of low pressure along the front. At the
upper levels, there is a deep trough moving across the Great Lakes,
and an area of low pressure over the desert SW.
With surface high pressure in control today, much of the area will
be dry, however lingering moisture near and along the weakening
front will kick off some showers and storms this afternoon into
early this evening, with the highest chance PoPs over far S/SW FL.
Morning sounding showed MU CAPE values around 2500 J/Kg and DCAPE
values around 600 J/Kg. While severe storms are not expected, a few
stronger storms are possible, mainly over the interior and towards
the Gulf coast, with strong winds over 40 mph the main threat. A few
lingering showers/storms are possible near the coasts overnight, but
otherwise clear to partly cloudy with low temps in the upper 60s
around the lake, to low and middle 70s elsewhere.
As the surface high shifts further to the east on Monday, the low
level flow becomes more southerly. At the same time, a cold front
begins to approach from the NW and reaches northern FL by Monday
evening. PWAT values are expected to increase to around 2 inches
with some interior locations approaching 2.25 inches during the
afternoon. Expect a wider coverage of storm activity on Monday,
although 12Z CAMS are still nowhere near in agreement, with some
solutions showing a fairly wet Monday and others showing much drier
solutions. Stayed fairly close with the previous forecast and capped
PoPs at 40%. Afternoon high temps will be in the upper 80s over most
of the area.
&&
.LONG TERM...
(Monday night through next Saturday)
Issued at 256 PM EDT Sun Oct 16 2022
An area of low pressure over the Great Lakes will push an
associated frontal boundary across the southeastern United States
into the peninsula of Florida on Tuesday. With plentiful moisture
ahead of the boundary and the drier, cooler air trailing it, the
chances for showers and thunderstorms will increase through the
week. The parent low will sit over the Great Lakes until late
week, allowing the frontal boundary to meander over the central
and southern portions of the peninsula. With that, the region will
remain in a wet pattern through late portions of the week when the
parent low finally ejects north and east into Canada, allowing the
frontal boundary to clear through southern Florida into the
straits and Bahamas. Some portions of Southwest Florida could
possibly see the dry air arrive by Wednesday or Thursday, which
could help temperatures there dip into the 50s or lower 60s by
Thursday morning. Some remoistening through the end of the week,
particularly along the Atlantic coast, could allow rain chances to
sneak back in by the weekend.
&&
.AVIATION...
(00Z TAFS)
Issued at 724 PM EDT Sun Oct 16 2022
Prevailing VFR conditions with winds beginning to shift more east-
southeast through the period. Sea-breeze driven convection is likely
for east and west coast sites beginning around 18Z. Short-fuse
amendments may be necessary if thunderstorms propagate too close
to sites although most activity should shift inland later into the
evening.
&&
.MARINE...
Issued at 256 PM EDT Sun Oct 16 2022
Near-cautionary east to northeasterly winds will persist across
area waters into early this evening, with seas running in the 3-5
ft range over the Atlantic waters (highest near the Gulf Stream).
Winds and seas will decrease Monday into Tuesday before
potentially increasing again towards the middle of the week behind
a cold front. Storm chances will be lowest today, before
increasing again early this week as a frontal boundary approaches
the area and then crosses the south FL waters mid week.
&&
.BEACHES...
Issued at 256 PM EDT Sun Oct 16 2022
Breezy E/NE flow will maintain a moderate risk of rip currents for
the east coast beaches today, with the risk becoming lower for
Monday and Tuesday as the winds decrease and eventually shift
offshore by Tuesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Miami 77 88 76 89 / 20 50 30 50
West Kendall 73 88 72 88 / 20 50 30 50
Opa-Locka 74 87 74 88 / 20 50 30 50
Homestead 74 86 73 87 / 30 50 30 50
Fort Lauderdale 77 87 75 87 / 20 50 30 50
N Ft Lauderdale 76 86 75 87 / 10 50 30 50
Pembroke Pines 74 86 74 87 / 20 50 30 50
West Palm Beach 74 87 73 87 / 10 50 30 50
Boca Raton 75 88 74 88 / 10 50 30 50
Naples 71 85 74 83 / 30 50 40 50
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&
$$
SHORT TERM...CMF
LONG TERM....RAG
AVIATION...Rizzuto
Area Forecast Discussion
National Weather Service Marquette MI
805 PM EDT Sun Oct 16 2022
.SHORT TERM...(Into Early Evening)
Issued at 226 PM EDT SUN OCT 16 2022
Water vapor imagery and RAP analysis show an amplified pattern
across N America. Strong ridges over western N America and also the
N Atlantic, extending across Greenland, are locking in a trof from
the Canadian Arctic across Hudson Bay into the Great Lakes region.
130kt upper jet axis nosing south through Manitoba into western MN
today will work to amplify the trof over the Great Lakes region.
12hr height falls at 500mb from 18z today-06z tonight max out at
around 160-170 m centered over central Lower MI. Upper diffluence
from the left exit of the upper jet/deep layer forcing from the
height falls will support a continued expansion of lake enhanced
pcpn off of Lake Superior today into this evening under increasing
nw low-level flow. There is very little to no caa today, but later
in the day, caa increases over western the far western fcst area
Lake Superior into the far western Upper Mi. Based on wetbulb zero
heights, ptype should be mostly -shra today, except over the higher
terrain where wetbulb zero heights are down to around 1000ft agl,
suggesting a mix of -shra/-shsn at times. Late in the day, snow may
become more predominant ptype over far western Upper Mi due to the
caa there. Any snow accumulation thru 00z today shouldn`t be more
than 1 inch on grassy sfcs, but with some positive area developing
on fcst soundings/increasing convective cloud depth, graupel will
likely become a much more common occurrence with some of the showers
as the day progresses. Temps will be steady to slowly falling in the
upper 30s to lower 40s.
.LONG TERM...(Tonight through Sunday)
Issued at 436 PM EDT SUN OCT 16 2022
Deep longwave trough extending from the Arctic into the Upper Great
Lakes region is the feature responsible for this well-advertised
event. Tomorrow, a low will emerge along the base of this trough.
Low pressure then attempts to cut itself off heading into the middle
of the week, and is largely successful, sitting and spinning over
southern Ontario before collecting itself and meandering into Quebec
in the latter half of the week. By week`s end, a pattern change
emerges, with zonal flow dominating into next weekend.
Given the aforementioned setup of the longwave trough tonight, cold
air will rapidly spill into Upper Michigan, allowing for quick
transitions over to snow from W to E after sunset. With the low`s
center finding itself over Lake Huron into the Georgian Bay by
sunrise tomorrow, temps in the Ern third of the forecast area look
to remain on the warmer side through tonight into tomorrow, ensuring
much lower accums as compared to locations in the central and W. As
that low continues moseying Erd throughout tomorrow, colder temps
aloft will be able to push further E, allowing for more SN as
opposed to RA by sunset tomorrow. Looking at 850mb temps in
particular, they look to largely remain in the -6 to -9 C range
through overnight Tues, which is then when the low makes its move
to start pulling away from Upper Michigan, as discussed above. A
return of above 0 C temps after early Thursday means any precip
that occurs will be in liquid form.
As for snow amounts, multiple factors will all play a contributing
role as to how the final observed totals end up. First, must note
here that no major changes were made to this forecast update as
overall, there remains good consistency and agreement. That
established, amounts will be influenced by: 1) how the snow ratios
end up panning out; 2) how much daytime "heating" and ground temps
inhibit depths; and 3) QPF -> QPE. For 1: there are higher degrees
of uncertainty in ratios, particularly as it relates to not only mid-
level temps, but sfc temps and the modification courtesy of the
Great Lake of Superior influencing ratios. It is possible for higher
than 10:1 ratios, but have capped them at less than 15:1 since
anything higher than that seems like a low possibility. For 2: the
sun`s angle is still respectable and despite the recent cold spells,
ground temps are still running well, well above freezing. But, with
cloud cover, that will of course moderate the sun`s influence, and
once snow accumulates, those ground temps will be less important as
snow piles on. For 3: QPF has been fairly consistent, but still some
adjustments are playing out as the event inches closer. Bottom line:
yes, there could be deviations in what ends up being observed
versus these forecasts, but as of this writing, those deviations
appear relatively minor in the overall outlook. As for what to
expect from an impact perspective, which is far more important
than focusing on amounts: this will be a highly-impactful event,
particularly for those within the higher terrain areas within the
Nrn snow belts. At a minimum, roads will become very sloppy and
unfavorable for driving, and in the more worst-case scenario
situations, some roads could become impassible where road
treatment isn`t occurring. Additionally, as well advertised, the
winds will only serve to exacerbate not only visibilities for
motorists, but agitate trees that still have leaves on them
coupled with the burden of the wet snow.
Precip chances start winding down from W to E on Tues, with
lingering chances in the Ern portions through mid-week, courtesy of
that aforementioned low hanging around. A disturbance swiping past
the forecast area late in the week could bring some low-end PoPs to
portions of the U.P., but then once that zonal flow sets up, looks
to be dry next weekend.
As expected, temps for at least the next 48 hours will run well
below normal for mid-October. Any meaningful amount of snow on the
ground by Tues would influence temps in the negative sense a bit,
especially since Nrly flow will still be dominant, but from Wed
onward, temps will be on the rebound, edging toward climo by week`s
end.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 805 PM EDT SUN OCT 16 2022
MVFR conditions are already prevailing at KIWD this evening where
precip has turned to snow. Deteriorating conditions will then
commence at KCMX and KSAW, too, over the next few hours as a
disturbance and cold air mass dip into the region. Strong north-
northwesterly winds will also further worsen the situation with
gusts up to 35 to 40 kts throughout the TAF period. By Mon 03Z,
expect all TAF sites to be at MVFR/IFR where they will stay through
the end of the TAF period. Also, would not rule out periods of LIFR
at times during heavy snow.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 459 PM EDT SUN OCT 16 2022
Winds will rapidly ramp up tonight, with northerly gales appearing
as early as just after sunset. Late tonight into early tomorrow,
storm-force wind gusts will emerge; see the latest Marine Weather
Statement for additional information. As tomorrow progresses, the
winds will only increase further, maxing out tomorrow night, with
gusts potentially exceeding 50 kts at times. Confidence is growing
for storm-force gusts to also occur in the far eastern portions of
Lake Superior late tomorrow; therefore, mariners and those with
marine interests should be aware of this potential. At least gales
remain well into Tuesday, with slackening occurring Wednesday
through the remainder of the week, looking to generally remain
less than 30 knots.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Storm Warning until 8 PM EDT Monday for MIZ001-003.
Lakeshore Flood Advisory from 2 AM Monday to 2 PM EDT Tuesday
for MIZ001.
Winter Storm Warning until 2 PM EDT Monday for MIZ002-009-084.
Winter Storm Warning until 11 AM EDT Tuesday for MIZ004-005.
Lakeshore Flood Warning from 3 AM Monday to 2 AM EDT Wednesday
for MIZ005-006.
Winter Storm Watch from Monday afternoon through Tuesday morning
for MIZ006-013-014-085.
Lakeshore Flood Advisory from 10 AM Monday to 2 AM EDT Wednesday
for MIZ007.
Winter Weather Advisory until 2 AM EDT Tuesday for MIZ010.
Winter Weather Advisory from 2 AM Monday to 8 AM EDT Tuesday for
MIZ011.
Lake Superior...
Gale Warning until 11 PM EDT Monday for LSZ162.
Gale Warning until 8 PM EDT Tuesday for LSZ240>242-263.
Storm Warning until 11 AM EDT Tuesday for LSZ243>245-248>250-
264>266.
Gale Warning from 11 AM Tuesday to 2 AM EDT Wednesday for
LSZ243>245-248>250-264>266.
Gale Warning until 2 PM EDT Tuesday for LSZ246-247.
Gale Warning from 5 AM Monday to 2 AM EDT Wednesday for LSZ251-
267.
Lake Michigan...
Gale Warning from 5 AM Monday to 8 PM EDT Tuesday for LMZ221-248-
250.
&&
$$
SHORT TERM...Voss
LONG TERM...lg
AVIATION...TDUD
MARINE...lg
Area Forecast Discussion
National Weather Service Phoenix AZ
445 PM MST Sun Oct 16 2022
.UPDATE... 00Z Aviation Discussion
&&
.SYNOPSIS...
Isolated shower and thunderstorm activity is expected this
afternoon south-central Arizona through late this afternoon. High
temperatures will be below normal with readings in the upper 70s
to mid 80s. Dry conditions are expected Monday through Thursday
with high pressure situated over the western states. Expect desert
highs in the upper 80s to low 90s. Late in the week, a weakening
weather system will move through the region bringing a modest
potential for rain late Friday and Saturday.
&&
.DISCUSSION...
Latest water vapor imagery and RAP streamline analysis reveal the
center of the mid-tropospheric closed low is centered across
southwestern Maricopa/western Pinal County. At the surface,
conditions remain quite moist in the wake of yesterday’s rainfall
with dewpoints in the upper 50s and lower 60s. Temperatures are
also running several degrees below normal for this time of year,
generally in the 70s across the lower deserts. If the daily high
temperature fails to reach the 80 degree mark in Phoenix, this
would be the first occurrence in over 6 months. The last time the
high temperature was this low was on April 13th, when it only
reached 76 degrees. This morning was also relatively chilly, with
temperatures bottoming out at 63 degrees at Sky Harbor, making it
the coolest reading since May 13th.
Latest mesoanalysis indicates an area of uninhibited CAPE is
situated across central Arizona, owing to the residual moisture
and anomalously cold temperatures aloft near the center of the
low. Ahead of the low, robust vorticity-forced ascent in the
eastern flank is combining with the instability and orographic
lift, resulting in scattered showers and isolated thunderstorms
across the higher terrain east of Phoenix, particularly near
Superior. These cells are hugging the mountains and showing little
movement, resulting in persistent heavy rain with rates exceeding
an inch per hour.
Models remain in good agreement the closed low will continue to
move slowly but steadily eastward through tonight. Although the
earlier Flood Watch was allowed to expire this morning, conditions
remain favorable across the higher terrain east of Phoenix
(including the burn scars) for localized flash flooding through
early this evening. Further west across the lower deserts
including Phoenix, the lingering instability will likely promote
the continuation of isolated showers and thunderstorms. The
strongest cells will be capable of producing brief heavy rain and
pea-sized hail. With the relatively moist conditions in place,
latest HREF indicates probabilities less than 10 percent for
strong wind gusts. CAMs are in good agreement the convection will
fizzle out with the increasing subsidence and the loss of
heating/insolation late this afternoon.
&&
.PREVIOUS DISCUSSION...
The western edge of the trough associated with the upper low will
linger over the forecast area Monday as a trailing short wave from
the north moves through. Not enough moisture/instability/forcing
to work with for anything more than single digit PoPs over the
higher terrain. Otherwise, highs warm over south-central AZ into
the 80s (little change west of there). By Tuesday, another upper
low takes shape off the West Coast as short wave energy moves into
the southern branch of a split in the Westerlies. However, strong
high pressure over the western CONUS will keep that at bay for a
while and enable a modest warming trend (highs in the upper 80s to
low 90s through Thursday).
Late in the week, the upper low moves inland. Looking at global
ensemble means, the GFS is faster than the EPS. Cluster analysis
indicates that there is spread within each of those modeling
systems. Also, there are differences in how much the system
weakens. But, it appears that it will not be nearly as deep a
system as the one we have now. Also, it doesn`t appear there will
be as much moisture to work with - despite the possibility of a
tropical system as it looks to dissipate or move inland well
south of Cabo San Lucas. But, modest precip chances return for
late Friday and Saturday - mainly over south-central AZ.
&&
.AVIATION...Updated 2340Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Tranquil weather conditions expected through the TAF period.
Generally light easterly winds will prevail, with extended periods
of variability in the wind direction likely.
Southeast California/Southwest Arizona including KIPL and KBLH:
Tranquil weather conditions with generally light and variable
winds expected through the TAF period.
&&
.FIRE WEATHER...
Storm activity will be much less today compared to yesterday. But,
isolated to scattered showers and thunderstorms can be expected -
mainly over south-central Arizona - and they will be capable of
producing localized flooding. Dry conditions can be expected
Monday through Thursday before a chance for modest rain amounts
late Friday and Saturday. MinRH of 40-60% today will decrease to
20-40% by Wednesday then increase by 5-10% over south- central AZ
on Saturday. Overnight recovery will be very good tonight with
MaxRH of 70-100% then decrease to 45-75% by Wednesday night then
increase 5-15% Friday night. Overall, winds will favor easterly
directions over Arizona and northerly directions over southeast
California through Thursday. Anticipate locally breezy conditions
on Tuesday and Wednesday. Late in the week, south and southwest
directions will be favored during the daytime.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...AJ
AVIATION...Lojero
FIRE WEATHER...AJ