Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/12/23
Area Forecast Discussion
National Weather Service La Crosse WI
538 PM CST Sat Nov 11 2023
.DISCUSSION...(This evening through Saturday)
Issued at 235 PM CST Sat Nov 11 2023
Key Messages:
- A quick disturbance will bring rain/snow mainly north of I-94.
Confidence is very high (90% chance) in seeing measurable snow
greater than 0.1" north of Hwy 29, with the HREF showing an increasing
trend from the 00z to 12z runs, with probabilities of seeing 1"
or more increasing from 40% to 80% in northeastern Taylor
County. |
- Warmer and mainly dry for much of the work week with
unseasonably warm temperatures. Temperatures 10 to 15 degrees
above normal. 100% probability of highs at or above normal 48deg
Mon-Thu at KRST/KLSE). Normals mid to upper 40s. Although some
60s are forecast, the records are in the upper 60s to lower 70s,
so not forecasting records.
Rain/Snow expected along and north of I-94 this evening & tonight:
The stage is set for a quick hitting round of rain & snow this
evening and overnight as a shortwave trough progresses north of our
region over the course of today and tonight. Current water vapor
imagery shows an area of spin advecting eastward across northern
Minnesota this afternoon. Interactions with this system and a warm
front pushing northward throughout the day today will allow for a
generalized area of weak Q-vector convergence enhancing lift over
north-central Wisconsin during the evening hours. As the warm front
begins to push north however, the more recent CAMs have been really
latching onto a more robust solution with the 11.16z RAP showing a
600mb frontogenesis band developing over north-central Wisconsin
associated with the aforementioned warm front. As a result, much of
the CAMs have a brief period late this evening of more robust
precipitation across north-central Wisconsin.
The key questions with this disturbance will be how much changeover
to snow we end up seeing and if snowfall rates will be able to
overcome the marginal surface environment to accumulate
significantly. The 11.16z RAP forecast soundings this evening
across north-central show a fairly broad saturated layer at
800-600mb centered right in the dendritic growth zone with fairly
robust lift in that layer from the previously mentioned
frontogenesis. Additionally, not overly impressive but sufficient
moisture is present shown with precipitable water values being
around 0.5" and weak 850mb moisture transport. As a result, when
considering the somewhat favorable mesoscale environment and
sufficient moisture, there is some concerns that this could be
brief, fast accumulating band of snow across north-central
Wisconsin with the 11.16z RAP and HRRR showing model reflectivity
in the 30-40dbz range suggest brief heavy snowfall rates could
occur which could lower visibilities at times. The trouble with
the higher rates is it is collocated with the frontogenesis band
itself which as shown across the 11.12z CAMs deviates from model
to model and is only on the order of a couple of counties wide.
Accumulations from this event could significantly differ by a few
miles, even across Taylor county from little to no accumulation to
an inch or two. The 11.12z HREF continues to increase probabilities
of measurable snow across Taylor county with high confidence (80-90%
chance) of seeing at least 0.1" at Medford with medium confidence of
seeing at least an inch (40-60% chance) with higher confidence (70-
80% chance) in the northeast fringe of Taylor county of seeing an
inch. This continues to show an increasing trend from the 11.00z
that measurable snow is likely across north-central Wisconsin.
However, with the CAMs exhibiting a more northward trend in the most
recent runs with the frontogenesis band, much of the recent snow
totals in the 11.18z RAP, HRRR and NAMnest keep the bulk of the snow
north and east of Taylor county, suggesting lower totals. The bottom
line to takeaway from this would be that either way accumulations
will be fairly light with the highest totals being an inch or two,
likely our northern areas will see some measurable snow but highest
amounts will be dependent on where the frontogenesis band sets up.
Much above normal temperatures for the work week:
We remain under northwest flow aloft Sunday, however the low level
flow is from the southwest with 850mb temperatures 3 to 6 deg. C.
and quite a bit of sunshine. Temperatures rise into the 40s and 50s
for Monday. The mid-tropospheric ridge builds in across the central
part of the country Monday and Tuesday; flattening Wednesday with a
cold front pushing into the Northern Plains Thursday. 850mb
temperatures warm to around +9 deg. C resulting in surface
temperatures in the 50s and 60s Monday through Thursday. Cloud
cover will come into play more for Wednesday and Thursday with the
more zonal flow Wednesday and troughing moving into the Plains
Thursday.
The operational GFS is a little quicker lowering heights for
Thursday, however the LREF ( GEFS/EPS/CMC ensembles) all show a 100%
probabilities of temperatures reaching 48 degrees or warmer for
RST/LSE Monday-Thursday and 50 to 80% for Friday. Normals are in
the mid to upper 40s. The NAEFS shows 850mb temperatures 1 to 2
standard deviations above normal. The EC EFI has 39 to 63 percent
of the ensemble distribution is higher than the climate maximum.
Although some 60s are forecast, the records are in the upper 60s to
lower 70s, so not forecasting records.
The cold front should push in Thursday night or Friday morning, thus
cooler highs are forecast to cool to the 40s and 50s. Surface high
pressure remains over the area Saturday with highs still above
normal in the 40s and 50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 531 PM CST Sat Nov 11 2023
Mid-clouds will continue into early Sunday morning and then skies
will clear. There may be some sprinkles for the TAF sites this
evening, but no visibility restrictions are expected. The winds
will be southerly through Sunday morning and then shift to the
southwest on Sunday afternoon. Wind speeds will remain at 10 to
15 knots.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Naylor/Zapotocny
AVIATION...Boyne
Area Forecast Discussion
National Weather Service State College PA
1016 PM EST Sat Nov 11 2023
.SYNOPSIS...
High pressure building across the Commonwealth will provide a
dry and seasonably chilly weekend.
Milder temperatures are anticipated on Monday, with winds
shifting to southwesterly. Our weather is expected to remain
dry.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
An area of stratocumulus at 5000-6000 ft AGL persists across
the I-80 corridor of central PA at 00z Sun, although the trend
has been for dissipation of this cloud shield from both the
north and the south over the past 3 hours. Latest HRRR shows
moisture over the southern half of the CWA increasing at 850 mb
after 02z, likely reinforcing clouds along the ridge/valley
region along and south of I-80 through late tonight. A jet max
passing to our south will also result in an increase in mid-
upper level clouds before daybreak.
Although the cloud forecast is uncertain, more cloudiness could
result in temperatures staying up near or just above the
freezing mark for most spots along and south of I-80. The
northern tier, which has already seen clearing skies, is most
likely to see temps dip down into the mid and upper 20s.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
High pressure will continue to build across the Commonwealth
Sunday. Lingering clouds in the morning will mostly dissipate
by the afternoon, with skies clearest around sunset. Highs on
Sunday will still be chilly, with most areas staying in the 40s.
With clear skies and light winds Sunday night, lows will drop
into the 20s for most of central PA.
A noticeably milder day is anticipated on Monday, with winds
shifting to southwesterly on the back side of departing high
pressure. Monday`s highs will recover into the 50s for the
majority of the Commonwealth.
The passage of a fast moving, moisture starved cold front late
Monday and Monday night will bring some cloudiness (mostly for
northern PA), but very likely no precipitation.
For Tuesday, morning cloudiness north of I-80 should have a
tendency to diminish with time, as a deep layer of dry air and
subsidence becomes dominant. Highs Tuesday afternoon should
range from the upper 40s over the northern mountains, to the
mid-upper 50s in far southern PA.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
1130 am Saturday update... There is decent agreement amongst our
various ensemble prediction systems for the middle and latter
portions of next week, so confidence in the forecast is
reasonably high. Towards the end of the period and just beyond
(Friday and next weekend), there is some customary uncertainty
as to the timing of an incoming northern stream upper trough and
associated surface cold front.
Generally speaking, an eastern CONUS upper ridge and mild/above
normal temperature pattern should prevail into Friday. Heights
should start to fall over the eastern states on Friday and into
the weekend, as a northern stream trough approaches from central
Canada and the upper midwest.
As for the daily sensible weather, rain free and mild conditions
are anticipated Wednesday and Thursday. Daily highs on both days
are likely to reach at least the lower 60s for many areas south
of I-80. On Friday, moisture and lift should increase ahead of
a surface cold front, with the probabilities for showers
increasing with time, especially across the northern mountains
and the Alleghenies/Laurels.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Late evening update.
Skies have cleared out in many spots. Minor changes so far.
Clouds are still just north of BFD, so the clouds could creep
back to the south later.
Small potential for some fog, mainly ground fog in isolated
spots late, but the airmass has dried out some from yesterday.
Yesterday morning featured a bit of light rain across the
far southeast. For now, will leave fog out. Will continue
to monitor the obs overnight.
Earlier discussion below.
00Z TAFS sent.
Expect some clouds at times into early Sunday given a northwest
flow of air over the Great Lakes. With warming aloft and time
of day, clouds may get trapped under the inversion tonight.
The airmass is dry, so not expecting any rain or snow showers
from the cloud deck. LNS did get some fog early this morning, as
that site was 5 to 8 degrees colder than nearby sites. Left fog
out of that site for now, will continue to monitor the
temperatures and dewpoints this evening.
High pressure will keep dry weather across the area into at
least Thursday. Not much change in the airmass, so not expecting
much change in conditions over the next few days.
Outlook...
Mon-Thu...No sig wx expected.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Jurewicz
NEAR TERM...Jurewicz/Colbert
SHORT TERM...Jurewicz/Colbert
LONG TERM...Jurewicz
AVIATION...Martin
Area Forecast Discussion
National Weather Service Raleigh NC
910 PM EST Sat Nov 11 2023
.SYNOPSIS...
High pressure over southern Ontario will continue to extend down
into central North Carolina through early next week. A wave of low
pressure will develop offshore of Georgia and South Carolina early
Sunday and dissipate as it tracks over the western Atlantic come
Monday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 910 PM Saturday...
Forecast is in good shape. This afternoon`s light rain persists
across our far SE with a slow exit taking place, however the next
round of light rain is just on our doorstep, over upstate SC and N
GA, poised to spread across primarily our southern half starting
after midnight through the ensuing 12-15 hours. While the 12/00z GSO
sounding and recent GOES imagery suggest thinner clouds across our
N, clouds are thicker and more plentiful across our S and SE and
back upstream to our WSW, and this will limit the nocturnal temp
drop tonight. Have nudged tonight`s lows up slightly, esp across the
S, as evening temps have trended a degree or two above forecast pace
beneath these thicker clouds. The extrapolated time of arrival of
this next round of rain across our southern two-thirds is running
close to the forecast pace, and will hang onto the upward trend of
pops toward good chance to likely, mainly from the Triangle to the S
and SE, overnight and toward Sun morning. Still expect a tenth of an
inch or less through tonight. Recent HRRR and RAP runs suggest a
slightly faster exit from our SE on Sun, but most ensemble system
means including the HREF are not this fast, so will not make any
large wholesale changes, just a slightly faster pop exit Sun of an
hour or so as a nod to these CAMs. Expect lows mostly in the 40s,
except near 50 far SE and some upper 30s far N. -GIH
Earlier discussion from 212 PM: The first wave of rain is currently
situated southwest to northeast from the southern Piedmont into the
central Coastal Plain. This band of light rain will continue to
track east-southeast over the next few hours, sagging south of most
of central NC by early this evening. Additional rainfall amounts of
0.05 to a tenth of an inch is possible across the Sandhills and
southern Coastal Plain.
Latest analysis at the surface reveals 1032 mb high pressure nosing
down into the area from southern Ontario. This northeast flow has
led to dry air mixing down across the Triad and northern Piedmont,
where rain has not occurred. Here, dewpoints have lowered into the
30s to even some 20s along the VA border.
Tonight, high pressure over southern Ontario will strengthen and
continue to extend across central NC. At mid-levels, we continue to
forecast a redevelopment of light rain after midnight and toward
daybreak Sun tied to another wave of energy in the southwest flow.
Models show a shortwave tracking up from GA/SC and reaching
southeastern NC by Sun morning. Coupled to the shortwave will be
frontogenetical forcing in the 850-500 and 700-500 mb layers and
isentropic ascent. Models continue to show a surface low developing
offshore of GA/SC by tomorrow morning. Nearly all guidance, except
for maybe the 12Z HRRR/ARW, have come in wetter for this second wave
as a result. The NAM is the wettest, showing nearly fourth tenths of
an inch near FAY by morning. This seems a bit of an outlier, though
a tenth of two tenths is certainly possible. The latest forecast has
trended wetter as a result, with the highest PoPs along/east of US-1
and especially over the Sandhills the central Coastal Plain. Some
light rain or sprinkles may even reach the Triad but little rain
amounts are expected there. Total rainfall with this second wave
will be about a tenth of an inch or less, highest in the south.
Lows will not drop too much with cloud cover in place. We are
expecting lows in the mid to upper 40s, except some low 40s to upper
30s in the far north and northwest where some breaks in the overcast
are expected overnight.
&&
.SHORT TERM /Sunday and Sunday night/...
As of 200 PM Saturday...
...Damp and Chilly Conditions Continue...
Overview: A low-amplitude shortwave trough approaching the southern
and central Appalachians Sunday morning will traverse the region
through the afternoon and then offshore Sunday evening. In the low-
levels, cool high pressure will wedge south into the Carolinas as
weak coastal low forms off the SE Coast.
Sunday: Renewed isentropic lift and upper jet divergence, along
with a northward buckling of the enhanced moisture plume extending
across the SE US will result in another period of light rain Sunday
morning and into the afternoon.
As has been the case over the past several days, high model spread
(the spread between between the 75-25th percentile ~ 0.30" across
the eastern Sandhills and southern coastal plain counties) and the
lack of run-to-run continuity continues to make it challenging to
define the northern extent of the light precip shield, which will
also strongly influence forecast highs as cold air damming ensues
across the area. With that said, the best chance for measurable rain
looks to be along and south of a line extending from Wadesboro to
Raleigh to Rocky Mount(similar to today). Rainfall amounts expected
to range from a few hundredths across the central portion of the
piedmont and coastal plain, to 0.10-0.20" across the Sandhills and
southern coastal plain.
WRT to highs on Sunday, the spread between the 75-25th percentile is
7-10 F across central NC, with the highest uncertainty along the
northern fringes of the precip shield and in the heart of the CAD
regime. A wetter scenario would lead to cooler daytime times highs
in the 50s, while drier solutions would yield warmer temps in the
lower 60s.
Sunday night: Subsidence in the wake of the exiting shortwave trough
will lead to NW to SE clearing during the late afternoon and
evening. Lows ranging from lower 30s over the Piedmont to mid/upper
30s south.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 220 PM Saturday...
Unfortunately, little progress will be made on drought conditions
across central North Carolina through the extended forecast. High
pressure will dominate the eastern United States for the first half
of the upcoming week. Meanwhile, low pressure will develop along the
Texas coastline Monday and move to New Orleans by Wednesday morning.
All 12Z guidance, including the GFS, GEFS, and ECMWF, are farther
south with rain with this system compared to previous runs. The
wettest time period with this system locally appears to be Wednesday
night into Thursday morning, and have only kept chance pops across
the west and south, with slight chance pops elsewhere. An isolated
shower could persist across the southeast Thursday night into
Friday. The next weather maker could be a cold front extending to
the south from a low pressure system moving across Canada. This
could bring a shower Friday night into Saturday, but models are not
in good agreement with this system.
Normal highs are in the low to mid 60s, and forecast highs are
within a couple degrees of these values through the first half of
the week before rising to the mid 60s to the low 70s by Friday and
Saturday. Similarly, normal lows are around 40, and lows will be
around climatology much of the period before some values in the 50s
return late week.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 710 PM Saturday...
Currently all TAF sites are seeing VFR conditions with northern
sites seeing 7-8k ft ceilings and KFAY reporting 4-5k ft ceilings.
Another round of light rain will spread across most of the region
overnight and into Sunday. Although, the Triad sites are not
expected to see any more precipitation tonight or tomorrow, majority
of the precip is expected to stay south and east of the Triad. KFAY
could see in increase in scattered light showers over the next
couple hours with MVFR conditions at times overnight and tomorrow
morning. As the bulk of the moisture moves across the NC/SC region,
showers as far north as KRDU and KRWI are not ruled out. Brief
period of MVFR conditions could be seen at these sites due to low
ceilings as the surface low offshore brings in ample moisture
through the day Sunday. Conditions are however expected to improve
by Sunday evening with clearing skies from NW to SE. Winds through
the period will be NE with winds picking up to 10 to 15 kts in the
afternoon.
Outlook: Sub-VFR potential under light rain will shift to VFR by
early Sun evening. VFR conditions are expected to continue through
Thu.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Kren
NEAR TERM...Hartfield/Kren
SHORT TERM...Locklear
LONG TERM...Green
AVIATION...CA/Kren