Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/13/24
Area Forecast Discussion
National Weather Service Gray ME
1021 PM EDT Sat Oct 12 2024
.SYNOPSIS...
Winds subside tonight as high pressure builds towards the region
from the west. An area of low pressure will approach on
Sunday...spreading a cool rain across the area with this low
passing south of the area Sunday night and Monday with rain
tapering to showers. Mountain rain and snow showers continue
through midweek with cool temperatures across the region as an
upper level low remains overhead.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
1020 PM Update...Only change to the forecast for the rest of the
night is to lower min temps some more as the better radiators
are radiating nicely as the low level decouple.
650 PM Update...Little change to the going forecast this evening
other than to lower overnight mins a few degrees in a few areas.
Winds continue to rapidly diminish and skies will remain clear
in many areas until well after midnight. This should promote
stronger radiational cooling at locations that decouple.
Previously...
High Impact Weather Potential: Minimal.
Pattern: Potent morning shortwave is over Nova Scotia and pulling
east with a region of mid level height rises just north and west of
the region moving overhead. The column is rapidly drying...with
PWATs falling towards 0.25". Through tonight...a weak ridge of
high pressure extending from a surface high over northern
Ontario will weaken across southern New England as low pressure
takes shape south of the western Great Lakes. A region of top-
down saturation will build towards the region overnight with
cloud cover and low temperatures being the primary forecast
focus.
Through this evening: Winds will subside this evening with
temperatures quickly falling in the continental polar airmass. By
8pm...expect readings in the upper 30s to around 40 in the
mountains...with upper 40s to lower 50s from the foothills to the
coastal plain.
Tonight: High pressure ridge axis to our west will gradually build
overhead and continue to weaken the northwesterly gradient as eyes
turn westward towards developing low pressure that will be over
northern Ohio by daybreak Sunday. Cloud cover associated with this
upstream low pressure does not arrive until well after midnight.
Despite some of the mesoscale guidance indicating non-zero
precipitation chances before daybreak...the lower troposphere will
be rather dry...with model soundings showing a wedge of dry air
persisting through the night. Therefore...expect that we/ll remain
dry through daybreak though clouds will thicken and lower.
We should have the opportunity to radiate for at least the first
half of the night...with the gradient allowing winds to decouple
after midnight. This makes the low temperature forecast a bit
tricky as the airmass is dry/cold enough to allow temperatures to
fall to freezing or below throughout the area. Have tempered the
colder statistical guidance with 2m temps from the NAMnest and HRRR
which will allow lows to drop just below 30 in the mountains...with
mid/upper 30s to the south.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
High Impact Weather Potential: Some potential for snow late
Sunday/Sunday night...particularly at elevation. Significant
travel impacts are not expected.
Pattern: Weak surface low pressure developing along the polar front
over Ohio daybreak Sunday moves to a position over northern PA by
evening as deeper mid level troughing arrives from the west. The
guidance envelope widens at this range /esp recent renditions of
the op EC/...though the EC- EPS favors more of a GFS/NAM
solution with weak low pressure continuing east northeast into
the Gulf of Maine by Monday morning. Forecast concerns center on
precipitation amount and type as a band of isentropic ascent
moves through the region...paralleling the path of the surface
low.
Sunday: East/west bands of lift/precip work into the region from the
west and south Sunday morning. This should allow rain to reach the
ground across central/southern NH Sunday morning...but likely taking
much of the afternoon to overcome initially dry air across
western ME. While the antecedent airmass is chilly...boundary
layer temperatures look too warm for anything but rain except
over the terrain...especially since it takes most of the day to
spread precip towards the international border. QPF during the
day is rather light...trace north...to 0.25-0.40" south. The
timing of the arriving clouds and precipitation is ideal for
keeping temperatures cool. Blending in some 2m temperature
guidance from the NAM/HRRR keeps NH largely in the 40s for the
day...with upper 40s to lower 50s from north to south across
western ME where precipitation will arrive later.
Sunday Night: With low pressure passing south of the region Sunday
night...expect bands of rainfall to continue with rates increasing
somewhat as the low makes it/s closest approach and mid level
forcing strengthens. Where it/s cold enough for possible snow in
the far north...forcing for ascent is weakest. Therefore...while
some snow is likely in the mountains...at lower elevations any
snowflakes that occur will likely struggle to accumulate with
boundary layer wet bulb temps above freezing. Certainly a raw
night...with lows in the 30s north to mid 40s south. Overnight
rainfall amounts look to reach 0.25-0.50".
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Pattern Overview: An active Fall pattern begins as a potent
vertically stacked low pressure system crosses the region on
Monday and then continues to meander to our north through
Tuesday. Afterwards, the 500 mb closed low remains overhead on
Wednesday before pulling away Thursday morning. Another trough
quickly dives through Thursday night before heights look to
build on Friday and Saturday.
Impacts:
* Potential for snow continues through the first half of the
week in northern zones, mostly at elevation. No significant
travel impacts expected.
Details: 12Z hi-res guidance is much more progressive with low
pressure moving through, so ongoing precipitation south of the
mountains may be more in the way of widely scattered rain
showers by Monday morning, where as more stratiform rain and
snow will continue in the mountains and North Country as
moisture wraps around. Precipitation will be light with snow
accumulations less than an inch, but still enough to make any
untreated roadways slick for the morning commute. Showers begin
to taper off early in the afternoon as low pressure races off to
the northeast, but they will continue in the mountains as the
low begins to retrograde back to the west prolonging upslope
flow. Again, precipitation will remain light and by this point
will mostly be isolated to the higher terrain. Light upslope
snow showers look to continue in the mountains through Tuesday
with dry conditions elsewhere as a drier airmass moves in.
Tuesday also looks like another blustery day with westerly winds
gusting 20-25 mph.
Low pressure departs off to the east Wednesday slowly bringing
upslope snow showers to an end. Surface high pressure then
builds in which will begin to clear things out. High
temperatures on Wednesday and Thursday will generally be in the
40s and 50s as it looks like we have mostly clear skies and well
mixed forecast soundings. This will get low temperatures into
the 30s each night as well, but still above freezing across much
of the interior and coastal plain.
The drying and warming trend continues through Friday and
Saturday as heights continue to build, pushing 850mb temps close
to 10C based on the latest ensemble guidance. Trends will have
to be watched as another potentially prolonged dry period may
bring about fire weather concerns as foliage gets past peak and
ends up on the ground. Also of note, the current forecast pushes
Portland and Concord into the top ten for latest Fall freezes,
with Concord more likely to see one this week.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Short Term...
Summary: Winds diminish as high pressure builds towards the
region tonight. Low pressure approaches Sunday...moving into the
Gulf of Maine Sunday night with deteriorating conditions in
rain.
Restrictions: VFR at the moment and expect this to continue through
tonight. Clouds increase after midnight...with light rain reaching
LEB by mid-late morning Sunday. Deteriorating conditions are
expected as rain overspreads the remainder of the region Sunday with
LIFR/IFR developing and continuing through Sunday night.
Winds: Northwest winds 20g30kts will subside through this evening
before becoming light and variable after midnight. Winds will remain
light on Sunday...generally less than 5kts.
LLWS: LLWS is not expected through Sunday night.
Lightning: No lightning is expected through Sunday night.
Long Term...MVFR/IFR conditions will linger into Monday as rain
and snow showers come to an end. Most terminals should be VFR
by Monday night with the only exception being HIE as snow
showers will continue in the mountains. This will be the case
through Wedensday with VFR becoming the prevailing condition at
all terminals by Wednesday night. Westerly winds gusting 20-25
kts are possible Tuesday.
&&
.MARINE...
Short Term...Winds and waves will subside through this evening
bringing an end to gales with a respite for late tonight through
Sunday evening before northeasterly winds strengthen to SCA
levels Sunday night as low pressure moves into the Gulf of
Maine.
Long Term...Low pressure moving over the waters will bring seas
up to 5-6ft Monday, where they will remain until they begin
subsiding Wednesday. Winds will be generally westerly once low
pressure moves out Monday afternoon. Winds will be gusting
generally 20-25 kts through Wednesday.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
SYNOPSIS...
NEAR TERM...Arnott/Ekster
SHORT TERM...Arnott
LONG TERM...Baron
AVIATION...
MARINE...
Area Forecast Discussion
National Weather Service Indianapolis IN
944 PM EDT Sat Oct 12 2024
.KEY MESSAGES...
- Partly cloudy overnight.
- Partly cloudy and cooler on Sunday.
- Coldest air of the Fall for early next week with frost expected on
a few mornings
- Other than low chances for showers across the northern counties
Saturday night into Monday night, dry weather will persist
&&
.FORECAST UPDATE...
Issued at 943 PM EDT Sat Oct 12 2024
Hi-Res soundings, obs and GOES-16 IR loop all support scattered
cloud cover overnight as an upper trough moves into the western
Great Lakes and a cold front drops southeast into the upper Wabash
Valley toward daybreak. Winds behind the front will shift to the
northwest. Meanwhile, MRMS radar mosaic and CAMs suggest only
perhaps at worst a few sprinkles or isolated showers are possible
overnight, mainly well north of Indianapolis. We decided to just
pull showers completely with very low PoPs matching up nicely with
adjacent offices.
&&
.SHORT TERM (This evening through Sunday)...
Issued at 157 PM EDT Sat Oct 12 2024
Synopsis:
Surface analysis early this afternoon shows a frontal boundary
stretching from northern PA, across northern OH and northern IN to
western IL. Low pressure has developed along the front over IA.
Strong surface high pressure was found over the deep south. Another
area of high pressure was found over the Great Lakes. GOES16 shows
mid and high clouds along and ahead of the frontal boundary,
including across Central Indiana, progressing southeast. Aloft
Pacific northwest flow remained in place as a weak ridge was found
over the western CONUS, resulting in NW flow from the northern
plains into the Ohio Valley. A weak short wave was found over the
upper Midwest, generating some showers over MN and NW WI. Additional
showers had developed of NE IN and NW OH. Dew points across the area
were surging higher, into the 50s.
Tonight -
Models suggest the short wave across the upper Midwest will continue
to dive southeast toward the eastern Great Lakes through the evening
and overnight. This is expected to drag the newly developed surface
low eastward along the frontal boundary across northern Indiana
tonight, along with an associated cold front. HRRR fails to generate
much in the way of precipitation with these passing features this
evening and overnight, hinting at the best chances across northern
Central Indiana. Forecast soundings do not show strong saturation
within the mid and lower levels, but do suggest steep lapse rates
with conditional instability. Thus will limit pops this evening and
overnight to the northern most parts of Central Indiana, including
Lafayette, Kokomo and Muncie. Any precipitation should be rather
light with low amounts expected. Points farther south, being farther
away from the forcing, should remain dry given the limited deep
moisture available.
Given the expected clouds overnight and also Central Indiana
spending much of the night in the warm sector, along with mixing
expected to continue, warmer lows are expected. Look for lows in the
upper 50s and lower 60s.
Sunday -
An upper trough over the upper Midwest is expected to settle across
Indiana by the late afternoon. Initially the upper flow will remain
northwesterly on Sunday morning, however the trough will dig across
central Indiana as the day progresses. Within the lower levels
cyclonic flow looks to remain in place due to the departing low
along with ongoing cold air advection through the day. Forecast
soundings fail to show much in the way of saturation, thus a dry but
cooler day will be expected. Look for highs in the lower to mid 70s.
&&
.LONG TERM (Sunday night through Saturday)...
Issued at 157 PM EDT Sat Oct 12 2024
Synoptic Pattern:
Central Indiana will begin to see its first taste of fall this week
as the portions of the Midwest and Ohio Valley will be beneath a
robust section of the Polar Jet. This is mostly due to a
strengthening PNA, an amplified West Coast ridge and subsequent
meridional activity on the downwind side of a supergeostrophic Polar
Jet. Initially, low level ridging will be the primary influence, but
this will adjust as multiple vorticity lobes develop in the cyclonic
curvature of the jet. The first low passage will be elongated as it
interacts with ridging over the SE (Saturday into Sunday), but the
second low passage will be backed by much cooler Canadian air,
allowing for the emergence of a cP airmass early next week. Strong
WAA within 850-700mb SW flow should allow for height rises and
ridging later next week, with more consistent broad ridging
development in the 8-14 day period as the PNA weakens.
Temperatures:
As mentioned, a more significant disturbance will arrive late on
Sunday attached with a cool Canadian Airmass. Timing on cold air
arrival is still varied amongst ensemble members, but generally the
expectation is for cold air to arrive Sunday night, creating fall
like conditions through Wednesday.
Mid level cloud cover within deep cyclonic flow is likely to keep
Sunday night temperatures from plummeting, but by Monday night,
skies should begin to clear. At this point is when overnight lows in
the mid 30s will be possible leading to some concerns for a
widespread frost event. There is still some uncertainty on overnight
lows Monday Night, but for Tuesday, confidence is growing a
widespread frost event. Those with interests/concerns with
vegetation should monitor closely in the coming days.
A warm up back to above seasonal is likely late next week with
tropospheric ridging and strong southerly flow expected. Highs back
into the 80s cannot be ruled out next weekend; Current ECMWF
Ensemble runs continue to show 99th percentile for 700mb
temperatures next week within the ridge.
Precipitation:
A secondary front will arrive Sunday, however this will be forced by
strong CAA, and will lack any significant moisture through the low
and mid levels, of which should lead to a dry frontal passage. As
the cold air arrives, steep vertical temperature gradients between
the Lake and low level temperatures could lead to enough low level
instability for lake effect precipitation. Most of this should
remain north of central Indiana, but a few isolated showers cannot
be ruled out over northern portion of the CWA late Sunday through
Monday.
Surface high pressure early to mid week, and then upper level
ridging late week should keep conditions dry through at least next
Saturday.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 708 PM EDT Sat Oct 12 2024
Impacts:
- Can not rule out an isolated thunderstorm at KLAF through 03z
- Non-convective LLWS possible between 05-13Z
- Winds will shift from SSW to NW after 11z-14
- Winds 290-320 to near 15 knots and gusts to near 25 knots
Sunday 20z to 01z Monday, mainly at KIND, KHUF and KBMG
Discussion:
A low level jet will bring the threat for non-convective low level
wind shear to mainly KIND, KHUF and KBMG overnight into the early
morning. Otherwise, can not completely rule out a thunderstorm at
KLAF this evening, but chances much too low to put in the TAF.
Should mostly see passing mid and high clouds tonight an d Sunday.
Winds will switch from SSW to NW just before and after daybreak as a
cold front drops down from the northwest with sustained winds to
near 15 knots and gusts to near 25 knots Sunday afternoon.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...MK
SHORT TERM...Puma
LONG TERM...Updike
AVIATION...MK
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
904 PM CDT Sat Oct 12 2024
.KEY MESSAGES...
- A few thunderstorms remain possible through around midnight
over northeast Illinois and northwest Indiana.
- Windy behind a cold front on Sunday that will usher in a
notable cool-down, with nightly frost and localized freeze
conditions through midweek.
- Lake effect showers are expected downwind of Lake Michigan
late Sunday into Tuesday.
&&
.UPDATE...
Issued at 904 PM CDT Sat Oct 12 2024
Unexpectedly strong mesoscale driven northeast winds into this
evening have been the main item of note, in the wake of an
outflow boundary continuing to surge south. Gusts have been up
to or over 35 mph on land and to 40+ mph on the lake, with a
rapid wave response on the lake. Speeds have since gradually
eased as the wind direction has become more easterly.
Convective trends through the early overnight are unclear.
Persistent activity over southern Wisconsin (occasionally
clipping far northeast IL) across southern Lake Michigan and
points east has since focused over southeast Lake MI and
southwest lower Michigan as of this writing. Warm advection
related expansion of mid-level cloud cover on the GOES-East
nighttime microphysics RGB is overlapped with the mid-upper
trough axis pivoting southward. This may yet portend renewed
convective initiation amidst continued steep mid-level lapse
rates, assuming MUCIN is eroded sufficiently. Held onto ~30-50%
chance PoPs over northeast Illinois and far northwest Indiana
for this reason and will continue to monitor satellite and radar
trends.
Finally, adjusted northwesterly winds upward slightly on Sunday
afternoon behind the potent cold front discussed in the short
term section below. Fairly stout pressure rises, robust cold
air advection, and steepening lower level lapse rates will lead
to a period of wind gusts up to 40 mph from the mid afternoon to
a couple hours past sunset. Model forecast soundings suggest
that sporadic gusts approaching 45 mph (wind advisory criteria)
are possible.
Castro
&&
.DISCUSSION...
Issued at 316 PM CDT Sat Oct 12 2024
Through Sunday Night:
A west-to-east oriented quasi-stationary surface frontal boundary
remains in place across the southern CWA (near the Kankakee River
Valley) early this afternoon. The front remains nearly stationary
into this evening as a weak surface wave of low pressure (now
over northern MO/southern IA) slides eastward into central IL
along the front. As this occurs, a strengthening low to mid-level
baroclinic zone north of the surface low track will foster a
period of scattered late afternoon and evening showers and
storms across portions of northern IL and IN.
At press time early this afternoon a 700 MB Theta-E axis is noted
now nosing in across northern IL into southern WI. Enhanced
moisture convergence along its eastern/northeastern periphery
continues to support the development of some widely scattered
showers and storms, most notably across southeastern WI, just
north of our area. Very steep lapse rates (700-500 MB lapse rates
in excess of 7C per KM per the SPC RAP mesoanalysis), are even
supporting some instances of sub-severe hail with these storms.
The main focus for these storms largely looks to remain
north/northeast of our area, especially for the next couple hours.
Thereafter, some south/southeastward progression could result in
some widely scattered storms impacting portions of far
northeastern IL, especially over some of the northern Chicago
suburbs. Far northeastern IL looks to remain along the western
periphery of the most favored axis of storms this evening, which
should extend eastward across Lower Michigan. As such, not
everyone will see showers and storms this evening. Far
northeastern IL in and around the Chicago metro area thus have
the best chances (~30-40%) for some scattered activity this
evening before we dry out area-wide overnight. Severe weather is
not anticipated, though some pea to penny size hail may continue
to accompany any of the stronger cores the develop into the area
given the very steep mid-level lapse rates.
Another, more potent, cold front will sweep southeastward across
the area Sunday afternoon as a vigorous mid/upper-level impulse
digs southeastward across southern Lake Michigan. Strong cold air
advection on increasingly gusty (35-40 mph) northwesterly winds
in its wake during the afternoon will usher in a much cooler
airmass. Accordingly, temperatures are likely to drop into the
upper 50s by early evening. Steep low-level lapse rates and the
development of a deck an of stratocu may also support some
scattered afternoon and evening showers, particularly across
northeastern IL in closer proximity to the track of the main
mid-level impulse.
Any lingering shower activity is expected to become confined
closer to Lake Michigan Sunday night as lake effect parameters
really ramp-up as the cold airmass spills over the warm lake
waters. Conditions may even favor some thunderstorms over the lake
late Sunday evening and night as a meso-low shifts southward
across southern Lake Michigan. Otherwise, continued breezy, but
dry and cool weather is expected across interior sections of
northern IL Sunday night into early Monday morning. Expect
temperatures to bottom out in the upper 30s to low 40s away from
the lake.
KJB
Monday through Saturday:
Early Monday, we will find ourselves seated beneath the windward
side of a deep, fast-moving upper trough centered over the Great
Lakes region. The cold core of the trough is expected to
interact with the relatively mild lake and provide us with a
good setup for some lake enhanced showers (and even some
waterspouts on Lake Michigan) throughout the day. We`ll likely
start the day with showers already building off of the lake and
falling on parts of the Chicago metro and northwest Indiana.
Lake surface temps in the middle 60s will yield as many as 1,000
Joules of lake-effect CAPE and lake-induced ELs reaching well
into the mid-upper levels. Additionally, we`re going to be
working with a strong, deep northerly fetch and plenty of low-
mid level moisture. Despite diurnal heating, we look to continue
destabilizing over the lake as we move toward midday thanks to
continued mid-level cooling. This will keep precip chances
going through the day with a few thunderstorms even possible,
especially during the late morning and afternoon. Coverage
during the day should be primarily confined to northwest
Indiana, but some showers may spill over parts of the Chicago
metro as well, especially during the morning before low-level
flow backs later in the day. This setup will also provide a good
chance for waterspouts, mainly over the open lake and nearshore
waters of Lake Michigan along the IN shore as a notable
convergence axis looks to develop down the spine of the lake.
Maintained a slight chance for waterspouts over these areas in
the forecast through the day.
The lake-effect activity should continue through the night and
into Tuesday morning. The trough base stretches westward late
Monday keeping us under the influence of the upper low a bit
longer before the system pulls away to the northeast during the
day on Tuesday, and precip chances will follow. Otherwise, in
addition to the lake- effect potential, the upper trough will
also bring noticeably cooler conditions to the area for the
middle of the week. Middle to upper 50s are forecast both Monday
and Tuesday. Forecast lows on Tuesday, Wednesday, and Thursday
mornings are down in the 30s across most of the area. Wednesday
should be our coldest morning of the week when we could see some
areas actually fall below freezing.
Steady height rises ahead of an approaching ridge will put us
back on a warming trend for the latter part of the week. 60s
could return as early as Wednesday with lower 70s in the
forecast area-wide on Friday. High pressure should keep
conditions quiet through the rest of the workweek. Another upper
trough looks to trek across the central CONUS next weekend and
bring additional rain chances to the region.
Doom
&&
.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 622 PM CDT Sat Oct 12 2024
The main aviation weather concerns are:
- Lingering potential (about 30% chance) for showers/TSRA,
mainly in the 02-06z window.
- Gusty NNE winds diminishing, eventually becoming northwesterly
tonight.
- MVFR cigs tonight into Sunday morning, mainly at the Chicago-
area terminals.
- Increasing northwesterly gusts through Sunday. Peak gusts
nearing 35 knots possible late in the afternoon.
Chances remain for a few additional showers/storms to develop
this evening, but remain too low to warrant TEMPOs or
prevailing lines for TSRA/VCTS. Have maintained PROB30 groups,
but pushed back and trimmed the timing a bit. MVFR cigs in the
vicinity of the lake should gradually expand this evening and
overnight. Some potential for cigs to drop under 020,
particularly at GYY, and will continue to monitor trends. Cigs
should lift with VFR conditions returning through late Sunday
morning.
Ongoing gusty NNE winds will gradually ease this evening,
eventually becoming northwesterly. Gusts will then increase
through late Sunday morning and especially during the afternoon
as a robust cold front arrives. Gusts may near 35 knots late in
the afternoon at times.
Carlaw
&&
.MARINE...
Issued at 904 PM CDT Sat Oct 12 2024
Key messages:
- Period of gale force winds expected Sunday afternoon through
Sunday night.
- Numerous lake effect showers with possible periods of
waterspouts Sunday night through Tuesday.
A strong cold front will shift southeastward across the lake
Sunday afternoon. In its wake, strong northerly winds will
develop and will continue Sunday night. Gale force winds of 35
to 40 kt are expected with this period of strong winds.
Confidence was high enough for an upgrade this evening of the
previously issued Gale Watch to a Gale Warning for the Illinois
and northwest Indiana nearshore waters. The Gale Warning will be
in effect from 3 PM Sunday to 7 AM Monday.
A much cooler airmass will shift over the lake in the wake of
this strong cold front. This will effectively set the stage for
several periods of lake effect rain showers and thunderstorms
on the lake Sunday night through Tuesday. Conditions also may
become favorable for at least a couple of periods of
waterspouts, particularly Sunday night into Monday, and again
on Tuesday. Stay tuned!
KJB/Castro
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 7 AM CDT Sunday for the IL and IN
nearshore waters.
Gale Warning from 3 PM Sunday to 7 AM CDT Monday for the IL
and IN nearshore waters.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Miami FL
725 PM EDT Sat Oct 12 2024
...New UPDATE, AVIATION...
.UPDATE...
Issued at 717 PM EDT Sat Oct 12 2024
CAMs are struggling tremendously with current convective regime,
with few members even initializing/handling the ongoing rainfall
well. RAP indicates a tropical moisture plume along the immediate
east coast, and subtle short-wave impulse which is allowing for
enhanced convergent flow and aiding isentropic ascent, along with
right entrance region of H250 jet streak. This has allowed for
scattered to numerous showers, which have produced 1-2 inches
across much of the metro region (with isolated pockets of 2-3
inches) A few additional inches of rainfall cannot be ruled out
through the night hours, though it may be a close call whether or
not the moisture plume lingers offshore or grazes the east coast.
Regardless, an isolated flash flood warning cannot be ruled out
through the night hours. Also worth mentioning that the CAPE
gradient along the east coast is quite pronounced, and while
thunderstorms are generally unlikely, we cannot rule out an
isolated storm or two, particularly along the immediate east
coast.
&&
.SHORT TERM...
(Rest of today through Sunday)
Issued at 105 PM EDT Sat Oct 12 2024
A weak warm front remains in place over the Florida straits south
of high pressure over the SE US. A mid-lvl shortwave will move
across the eastern Gulf this evening into tonight, which will aid
in the development of a weak frontal wave along the stalled
boundary. Deep-layer moisture will continue to spread north into
SFL ahead of this wave today into tonight, and this increase in
moisture will be coincident with isentropic ascent as low-lvl
warm advection continues (just above the surface). Given these
factors, scattered to numerous showers can be expected through
the overnight period, with the precip focus being over southern
and eastern portions of the area. The best window for heavy rain
looks to be tonight into early Sunday morning, as coastal
convergence maximizes over the east coast and the mid-lvl wave
axis approaches the area. Localized flooding remains possible over
vulnerable urban areas of the east coast, however, a limiting
factor may be lack of overland instability (as we will lie north
of the surface front) which may limit rain rates and confine
any thunder to the waters.
Sunday`s forecast will be largely dependent upon where the frontal
low develops/tracks. If it shifts far enough east into the
Atlantic, somewhat drier conditions could develop by Sunday
afternoon, whereas if it remains near the coast or just south of
the area there would be a lingering threat of coastal convergence
induced heavy rainfall. High temperatures should remain in the
mid 80s through the period, moderated by significant cloud cover.
Overnight lows will remain in the low to the mid 70s.
&&
.LONG TERM...
(Sunday night through next Friday)
Issued at 301 PM EDT Sat Oct 12 2024
Lingering frontal boundary across the FL Straits will keep the
threat of showers across the far southern peninsula on Monday into
Tuesday. Temps will remain mild with highs in the mid to upper 80s.
The climatological start of the dry season is mid October and right
on cue a cold front is expected to push south through the area mid
week aided by an upper level trough digging through the eastern US
and strong surface high pressure building in to the north.
Refreshing drier and cooler air will filter into the region, with
highs mid to late week only reaching the lower 80s, and lows in the
60s/70s. Dewpoints will fall into the 60s with some 50s possible
around the lake region. Rain chances start to increase late week
into the start of next weekend as the frontal boundary slowly starts
to lift back north across the Straits.
&&
.AVIATION...
(00Z TAFS)
Issued at 717 PM EDT Sat Oct 12 2024
MVFR conditions generally prevail into the night hours, though IFR
and even brief LIFR conditions cannot be ruled out, as SCT/NMRS
SHRA linger along the Atlantic coastline and near/over eastern
terminals. TSRA generally unlikely, though cannot rule out an
isolated storm or two near the terminals, though confidence was
not high enough to merit inclusion in TAFs. Winds generally ENE
around 10 kt. Prevailing MVFR conditions could linger into
tomorrow as well, particularly closer to Atlantic coastline.
&&
.MARINE...
Issued at 105 PM EDT Sat Oct 12 2024
Hazardous marine conditions will continue to subside today into
Sunday as the seas decrease across the Atlantic waters. Seas
should drop down into the 2 to 3 ft range by Sunday and remain low
into early next week. Scattered showers and a few thunderstorms
will be possible this weekend into early next week resulting in
brief periods of enhanced winds and seas.
&&
.BEACHES...
Issued at 105 PM EDT Sat Oct 12 2024
The high risk of rip currents will persist for the east coast
beaches through this afternoon, with the risk remaining elevated
into Sunday as onshore flow persists.
&&
.PRELIMINARY POINT TEMPS/POPS...
Miami 76 86 75 86 / 70 70 30 30
West Kendall 74 87 73 88 / 60 70 30 30
Opa-Locka 75 87 74 88 / 70 70 30 30
Homestead 76 87 74 87 / 70 70 30 30
Fort Lauderdale 76 84 74 85 / 70 70 40 20
N Ft Lauderdale 76 86 74 86 / 70 70 40 20
Pembroke Pines 76 87 75 88 / 70 70 40 20
West Palm Beach 75 85 74 86 / 70 70 40 20
Boca Raton 75 86 74 87 / 80 70 40 20
Naples 74 87 73 86 / 30 30 10 0
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Sunday evening for FLZ168.
High Rip Current Risk until 8 PM EDT this evening for FLZ172-173.
AM...None.
GM...None.
&&
$$
SHORT TERM...Carr
LONG TERM....CMF
AVIATION...SRB
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
709 PM CDT Sat Oct 12 2024
.KEY MESSAGES...
- Isolated to scattered rain showers this weekend along & north of I-
94.
- First stretch of below-normal weather in a month comes Sunday through
Tuesday. Widespread freezing temperatures likely Tuesday
morning.
- Temperatures rebound to back into 70s by the end of next week. There
is hope for the return of widespread wet weather in the
extended forecast.
&&
.DISCUSSION...
Issued at 1259 PM CDT Sat Oct 12 2024
A typical mid-October day has settled in across the Upper
Midwest. Temperatures are in the mid 50s to lower 60s with
southeast winds around 10 mph. Mostly cloudy skies associated
with this morning`s light showers and sprinkles should give way
to mostly clear skies by late afternoon early evening. All in
all it`s a pretty typical Fall day in MN and W WI... which we`ll
take after the past month+ of warmth! Any lingering showers or
sprinkles will be along and north of I-94 as the jetstreak
associated with the precip shifts east into the western Great
Lakes region. This morning`s showers produced a few hundredths
across central MN & W WI which is better than nothing at all.
Radar imagery looked more aggressive than the actual sprinkles
due to the significant amount of dry air between the cloud base
and surface. This led to a lot of evaporation and ultimately
limited our rainfall. Tonight will cool into the 40s with mostly
cloudy skies.
An upper level trough will drop into the Great Lakes region later
today and will influence our weather into the new work week. It`ll
bring us additional light shower chances and cooler air through
Tuesday before it exits the region. Sunday will be breezy on the
back side of the ULL. Winds out of the NW at 20 mph with gusts 35-40
mph can`t be ruled out. It will feel all of mid-october when
combined with the cooler temps. We`re on the western edge of the
ULL`s influence that will lead to varying forecasts for W WI vs W MN
Sunday - Tuesday. E MN & W WI will see overcast skies & isolated
showers in the afternoons with temps in the lower 50s. W MN will
stay dry with temps warming in to the mid to upper 50s with partly
sunny skies. Fire weather concerns should remain limited through
this stretch as minRH values stay at or above 35% area-wide thru
Tuesday. WPC QPF thru Tuesday isn`t spectacular... a few
hundredths total but it`s better than nothing we suppose.
The remainder of the period will see temperatures rebound back into
the 70s as the warm & dry pattern regains it`s hold across the
region. There is an encouraging signal for the extended forecast.
Guidance has teased a return to a more active, wetter pattern across
the central CONUS for the last 7 to 10 days of October. This starts
off with a storm system that will bring a round of widespread rain
into the region Friday/Saturday. This will be worth monitoring as it
could bring legitimate rain vs the sprinkles we`ve seen today.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 657 PM CDT Sat Oct 12 2024
Surface low currently up by Grand Forks will dive southeast to
northern WI tonight, deepening as it does so. This will drive a
strong cold front across the area tonight through early Sunday
morning. Winds ahead of the cold front will be light and
variable, but NW winds will start kicking pretty fast behind
the front, with BUFKIT soundings from the RAP and NAM showing
potential for wind gusts to be pushing 40 kts on Sunday. Given
this signal, did up wind speeds from the previous TAF some.
Another addition to these TAFs was the potential for some
fog at EAU ahead of the cold front from 6z to 10z. This will
come down to the amount of cloud cover present there. Less cloud
cover will create the potential for some dense fog before the
cold front arrives at EAU. Shower potential will be best closer
to the surface low, but the HRRR does show showers building
south along the cold front trough the night, with the south end
of those showers possibly clipping RNH/EAU around sunrise.
Behind the front, we`ll have extensive stratocu that will come
in in the 025-040 range, with some scattering out in the
afternoon for western MN.
KMSP...Looks like best shower potential at MSP will come with
any diurnally driven showers that develop Sunday afternoon, but
coverage of those showers this far west on Sunday looks pretty
sparse, so kept MSP dry. Some potential for MVFR cigs exists on
Sunday immediately behind the cold front from 12z to 16z.
/OUTLOOK FOR KMSP/
MON...VFR. Wind N 5-10 kts.
TUE...VFR. Wind N around 5 kts.
WED...VFR. Wind SW 10-15 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...BPH
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
819 PM EDT Sat Oct 12 2024
.KEY MESSAGES...
- Rain developing over the west half tonight, continuing into Sunday
along with cooler temps. Rain probabilities lower (30-60%) over the
eastern third.
- Cool with periods of rain continue through Tuesday.
- Temperatures returning to near/above normal by the middle to the
end of next week.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 204 PM EDT Sat Oct 12 2024
Early afternoon water vapor imagery and RAP analysis show ridging
extending across the northern US Rockies well north into the
Canadian Rockies. This ridge will build through Sunday and shift
eastward, which will force shortwave energy to dive southeast along
the downstream side of the ridge, consolidating and possibly cutting
off somewhere to our south in the WI/Lake Michigan vcty. For the rest
of today, mid/upper level moisture continues to stream into the area
ahead of leading weak height falls amid fast zonal flow. Thus far,
dry low-levels have kept precip at bay, with just virga noted on
area radars (possibly a few sprinkles over NE WI). Can`t rule out a
few light showers over Menominee/southern Delta Counties this
afternoon closer to better forcing and low level moisture.
Tonight into Sunday, forcing for ascent continues to increase as the
shortwave trough consolidates, fostering a low-level cyclogenic
response. Rain should become steadier due to low/mid-level f-gen
focused over the western UP at first tonight, then spreading east
and south through the night and into Sunday. Still some uncertainty
with how far east the rain expands to, as there will be a feed of
drier midlevel air from eastern Ontario that could counteract the
expanding precip shield. Precip efficiency should be maximized just
to the northeast of the surface low track where neutrally stable
profiles should conspire with forcing for ascent and potential for
pivoting bands to yield local QPF totals of 1-2" (per HREF LPMM).
Best potential for QPF>1" (30-50%) in a semicircle from the western
UP shoreline to near Houghton to western Marquette County and
southward to Menominee County. No hydro concerns expected with
ongoing drought conditions. Precip should tend to taper to showers
late Sunday afternoon from north to south, with lake effect
processes possibly moderated by the feed of dry air from the
northeast. However, some CAMs such as the 12Z HRRR show convective
cells coming onshore for the north-central and Keweenaw in the
afternoon as surface to 850 mb delta-T values increase to around 15C
and equilibrium levels rise to near 10kft. Sided closer to raw model
guidance over bias-corrected NBM for temps, which amounts to warmer
lows tonight (around 40) and cooler highs Sunday (mid-40s west to
mid-50s east).
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 556 PM EDT Sat Oct 12 2024
Much needed rainfall will persist into Sunday night and through mid-
week as the second of two shortwaves moves through Upper Michigan.
Along with it, though, will be reinforcing CAA aloft as temperatures
at 850 mb dip to -5C. This could provide some of the first
snowflakes of the season across the higher terrain. However,
predominant ptype through the event will be rain with the 80-100%
probabilities concentrated over the western portions of the forecast
area from Sunday night into Monday, eventually shifting to the
eastern third of Upper Michigan by Tuesday. Best chances for any
accumulative rainfall will be over the west and Keweenaw Peninsula
from Sunday night through Monday morning with most guidance
indicatiing an additional 0.25-0.50 inches of rain in addition to
Sunday`s qpf. Moisture will slowly decrease across the east,
however, as ensemble packages slowly begin to shift toward a drier
pattern late Monday into Tuesday. This is where some discrepancies
in models begin, though, with timing of dry air. By Wednesday,
confidence increases in the entire Upper Peninsula being in a
lull as dry conditions prevail through Thursday night under
high pressure. At that point then, focus will shift to the next
disturbance/rain chances.
As mentioned above, the cold airmass will engulf the Upper Penisula
through Tuesday with high temperatures struggling to even reach the
upper 40s. And, overnight lows will dip into the mid to upper 20s
by Monday and Tuesday nights across the interior. Lakeshores will
remain slightly more balmy in the upper 30s/low 40s. As surface
flow becomes south/southwesterly around mid-week, though, there will
be an uptick in WAA and a weak warming trend through the end of the
week. Daytime highs will slowly increase from the 50s on Wednesday
to 60s from Thursday through Saturday. Even some low 70s cannot be
ruled out on Friday.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 819 PM EDT Sat Oct 12 2024
VFR conditions will prevail at CMX and SAW through the period,
however, conditions are starting to deteriorate at IWD this evening
where obs have been wavering between VFR and MFVR cigs. Shower
activity in northern Minnesota and western Lake Superior is
beginning to uptick as a shortwave dives south into the Upper Great
Lakes. As showers overspread the west-central UP through Sunday
morning, lower cigs will begin to fill in at IWD where cigs/vsby are
expected to drop to MVFR. Moderate rainfall could briefly drop IWD
to IFR at times. CMX and SAW stay on the fringes of heavier precip,
though could see drops in flight category to MVFR and potentially
IFR in heavier showers. By the end of the TAF period, winds turn
N/NE late in the period lake effect/upslope MVFR strato-cu could
stick around.
&&
.MARINE...
Issued at 449 PM EDT Sat Oct 12 2024
Winds across the entire lake will remain below 20 kts through mid-
morning Sunday. At that point, though, east/northeasterly winds
will increase to 25 to 30 kts across much of the lake along with
lake effect rain showers through Tuesday morning as a system
slides southeastward across the region. As that low pushes
farther southeast, the 25 to 30 kt wind gusts will become more
confined to the eastern half of the lake by Tuesday afternoon
while backing to the northwest. All of the lake will then fall
below 20 kts again by Wednesday morning. Also of note, the
environment will remain conducive to waterspouts as convective
cloud depths Sunday afternoon/Monday look to climb to near 25k
with lake- 850mb delta temps climbing above 15 degrees and weak
winds at 850mb.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Thompson
LONG TERM...TDUD
AVIATION...BW
MARINE...JTP/TDUD
Area Forecast Discussion
National Weather Service Nashville TN
845 PM CDT Sat Oct 12 2024
...New UPDATE...
.UPDATE...
Issued at 838 PM CDT Sat Oct 12 2024
Quiet conditions will continue into the overnight across Middle
TN. A few clouds will build in from the west and we will see winds
5-10 mph overnight, this will keep fog away. 24 hour temperature
change is about 4-8 degrees and we will be looking at warmer
conditions tonight compared to last night, lows in the mid 50s to
lower 60s. Breezy southwest winds ahead of a fall cold front will
warm things up nicely with highs pushing well into the 80s for
most tomorrow. That cold front may kick off a scattered
thunderstorm or two in the evening for eastern areas.
&&
.SHORT TERM...
(Rest of today through tonight)
Issued at 1103 AM CDT Sat Oct 12 2024
Another beautiful sunny day across the midstate today with
current temperatures in the low to mid 70s. Highs are well on
their way to reach the upper 70s to mid 80s this afternoon.
Dewpoints have risen into the mid 40s to mid 50s across the area,
so it`s a tad more humid that past days. Tonight, southwesterly
winds will increase in the low levels ahead of the approaching
strong cold front expected Sunday night. These stronger winds
will keep fog formation minimal tonight, as well as keep low
temperatures up in the mid 50s to low 60s.
&&
.LONG TERM...
(Sunday through next Saturday)
Issued at 1103 AM CDT Sat Oct 12 2024
Sunday looks even warmer than today thanks to a strengthening
850mb jet forecast to increase up to 35 knots, which will advect
warmer air into the area along with low 60s dewpoints. Highs
should reach the 80s areawide, and it`s not out of the question
a few spots could touch the 90 degree mark. By late afternoon into
Sunday evening, the strong cold front will sweep from northwest to
southeast across the cwa, and lift along the front interacting
with the moisture axis could allow for a few showers and
thunderstorms to pop up in our eastern and southern counties prior
to the front exiting the area. Models disagree on how much if any
showers and storms will develop, with GFS/ECMWF showing more
activity while CAMs such as the HRRR have little if any.
Therefore only low pops appear warranted prior to frontal passage.
Despite the low precip chances, forecast soundings are showing
favorable parameters for strong or severe storms in our eastern
and southeastern counties, with MLCAPE reaching up to 1000 J/K,
0-3km SRH over 200 m2/s2, deep layer shear up to 40 knots, low wet
bulb zero heights down to 8k ft, and steep mid level lapse rates
as high as 8C/km. These values would all support large hail,
damaging winds, and possibly even the t-word - but only if a storm
can develop, which remains uncertain. SPC has highlighted our far
northeast in a marginal risk for severe storms tomorrow evening.
After frontal passage Sunday night, our weather will turn much
colder and stay dry for the rest of the week as a Canadian
airmass moves into the region. Highs will only reach the 50s and
60s for Monday through Thursday, with lows falling down into the
30s and 40s. Tuesday and Wednesday nights look to be the coldest,
with all of the midstate falling into the 30s. Appears very likely
we will see our first widespread frost of the season, as well as
our first freeze in parts of the Upper Cumberland and Plateau,
both of these nights. Fog can also be expected both Tuesday and
Wednesday nights on and near our area rivers and lakes due to the
large 40+ degree temperature difference between air temps and
warm water still in the 70s. Temps will begin to rebound late in
the week as an upper level ridge builds over the region, with
highs warming back into the 70s.
&&
.AVIATION...
(00Z TAFS)
Issued at 617 PM CDT Sat Oct 12 2024
TAFs are VFR. Middle Tennessee finds itself wedged between a
surface ridge to the east and an approaching frontal boundary to
our west. Surface winds will begin to increase overnight, and
strengthen further tomorrow with the passage of the aforementioned
cold front. Look for winds to shift to the west and then northwest
during the afternoon. And active weather resulting from the front
will likely be restricted to the Cumberland Plateau and will hold
off until after 00Z tomorrow evening.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 61 88 50 68 / 0 10 10 0
Clarksville 61 86 46 67 / 0 0 0 0
Crossville 53 80 44 61 / 0 10 30 0
Columbia 59 88 49 68 / 0 0 10 0
Cookeville 56 82 45 62 / 0 10 20 0
Jamestown 55 80 45 61 / 0 10 30 0
Lawrenceburg 58 87 49 67 / 0 0 10 0
Murfreesboro 58 87 50 67 / 0 10 20 0
Waverly 61 85 47 66 / 0 0 10 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Mueller
SHORT TERM...Shamburger
LONG TERM....Shamburger
AVIATION.....Rose
Area Forecast Discussion
National Weather Service Pocatello ID
258 PM MDT Sat Oct 12 2024
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
A longwave ridge of high pressure will continue to serve as the
dominant enforcer of our weather over the next several days,
resulting in fairly quiet, dry, and mild conditions. High
temperatures will continue to top out in the 70s to near 80, running
about 10 to 15 degrees above climatological norms for mid-October.
We do have a small, gradually weakening, closed low pressure feature
tracking "through" the ridge across Oregon into Nevada and Utah just
to our south and west, but other than a temporary increase in high
clouds through Sunday morning, this feature won`t be enough to cause
any significant pattern change for southeast Idaho just yet. For
those who want a (potentially?) last real taste of summer, enjoy
this weekend into early next week! 01
.LONG TERM...MONDAY THROUGH NEXT SATURDAY...
Quiet, mild weather will continue Monday, Tuesday, and at least part
of Wednesday for most areas, before a SIGNIFICANT pattern change
remains on tap arriving in tandem with a large low pressure trough
moving into the coast of British Columbia. High temperatures may
cool a few degrees Wednesday (largely due to increased cloud cover
more than anything else), before plummeting 20 degrees for Thursday
only reaching the upper 40s to low 50s. By Friday morning, low
temperatures may reach the 20s regionwide, definitively ending the
local growing season for areas that haven`t experienced a hard
freeze already. Meanwhile, showers will arrive across the Central
Mountains Wednesday afternoon, expanding across the rest of the
forecast area for Thursday and Friday. Snow levels are still
forecast to reach 5,500 to 6,000 feet AGL by Thursday, allowing
anywhere from a light coating to several inches of snow to
accumulate across most of our regional mountain ranges...especially
east of the I-15 corridor. A few flakes can`t be ruled out to valley
floors as well (especially during the colder overnight/morning
periods), although we are currently not expecting any accumulation
below about 6,000 feet. Deterministic models appear to be trending
toward eventually closing off a sfc low near or just south of our
area as the overall trough of low pressure moves east across the
western USA, although significant differences remain in how far
south this occurs and exactly how quickly impacts from this system
end. This system will also bring breezy conditions Wednesday through
Friday, with Thursday looking the strongest out of the WSW. The
Snake Plain/Arco Desert corridor may approach Wind Advisory criteria
with gusts near or just over 45 MPH, a scenario solidly illustrated
by the NBM 90th percentile and evoking a response in the ECMWF
Extreme Forecast Index (EFI). We`ll see how things trend over the
next several days. The true cold frontal passage is currently
expected Friday. Bottom line...welcome to Fall! 01
&&
.AVIATION...18Z Saturday to 18Z Sunday...
Overall, VFR conditions persist through the weekend. While a weak
upper level low is moving through today, it will only bring an
increase in mid and upper level cloud cover and a less than 10
percent chance of a shower at any TAF site. Winds are forecast to
remain light with gusts this weekend remaining below 15 kts. The
06Z HRRR smoke forecast shows a push of smoke from western WY
moving into eastern ID for Sunday morning. At this time, it isn`t
showing any impacts to CIGs or VIS, but it seemed worth it to at
least add a 6SM HZ into the TAF for DIJ and IDA for now. AMM
&&
.FIRE WEATHER...
Warm and overall dry conditions continue for the next several
days. A weak upper level low is moving through Eastern Idaho
today, but it brings a less than 10 percent chance of any showery
activity with it. Winds will remain light through the weekend with
afternoon gusts below 20 mph and temperatures stay in the mid to
upper 70s. Afternoon relative humidities continue to be quite dry,
ranging from the mid and upper teens to around 25 percent across
much of the area this weekend and through Tuesday.
Things will begin to change in a big way on Wednesday. Minimum RHs
will begin to increase ahead of our next system and while Wednesday
will still be a warm day, it looks like it`ll be the last 70-degree
day for a bit. Wind gusts will increase to the 25 to 30 mph range
for most of the area on Wednesday and precip chances will increase
from west to east as the day goes on. This is a strong cold front
that will drop our highs by some 15 to 20 degrees and the gusty
winds stick around through Thursday and begin to slowly diminish on
Friday. QPF continues to change with each model run, but this is the
best signal we`ve seen for measurable precipitation (including some
snow in the mountains) in almost a month. AMM
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Reno NV
100 PM PDT Sat Oct 12 2024
.SYNOPSIS...
* Breezy conditions are expected today along with chances for
isolated showers in northeastern California and northwestern
Nevada.
* While cooler temperatures are seen this weekend, a warming
trend is forecast for early next week.
* Another system arrives by midweek bringing cooler temperatures and
increasing shower chances to the area.
&&
.DISCUSSION...
The latest RAP analysis shows an upper air low over southern OR
causing a generally southwesterly flow over northern portions of the
CWA and westerly flow over southern portions of the CWA this
afternoon. Current radar imagery and surface observations report
isolated showers moving across Lassen, Plumas, and Washoe
Counties while the remainder of the CWA remains dry. Going through
the rest of today, model guidance projects the upper air low
progressing eastward to over the ID/NV border by the overnight
hours. At the surface, the latest run of the HRRR forecasts the
isolated precipitation chances to continue through the remainder
of the afternoon for the aforementioned county areas before
tapering off east to west in the evening as the upper low moves
through. QPF values in these areas range between a trace to a
tenth at the most should a shower occur. While the remainder of
the CWA looks to stay dry, westerly winds expect to gust up to
around 25 mph this afternoon within the CWA before becoming light
going into the night. High temperatures for today look to range
between the middle and the upper 70s in the valley areas while
the Sierra communities range between the 60s and the lower 70s.
Low temperatures for tonight expect to be in the middle 30s to
middle 40s in the valley areas with the higher elevations seeing
lows range from the lower 30s to the lower 40s. Dry conditions and
slightly cooler temperatures are forecast for the region on
Sunday with high pressure present.
To start the work week, ensemble guidance shows an upper air ridge
feature residing over the region on Monday and Tuesday in the wake
of the low moving eastward. Dry conditions continue and temperatures
expect to start warming up a bit as a result with daytime highs in
the 80s returning to portions of region on Tuesday. While minimum
relative humidity values look to be in the teens for some portions
of the CWA on Monday and Tuesday, lighter winds expect to curb any
critical fire weather concerns.
Forecast ensembles then show an upper air trough moving in over
the western CONUS late Tuesday going into Wednesday which will
change the CWA`s upper air flow to southwesterly. With this going
on above, models show a cold front starting to move through the
region early Wednesday bringing some precipitation chances with it
during the day though exact timing of this frontal passage still
is uncertain. These precipitation chances may continue going into
Thursday for areas closer to the OR border with the potential seen
for some light snow to mix in beginning during the nighttime
hours of Wednesday. Snowfall accumulation is not expected at this
time, but will continue to monitor the situation in case this
changes. Cooler temperatures continue to be the trend behind this
front on Thursday and Friday with daytime high currently looking
to not exceed the 60 degree mark on Friday afternoon. -078
&&
.AVIATION...
VFR conditions are expected to prevail for all REV terminals today
with breezy, westerly winds this afternoon gusting up to 20-25 kts.
The latest run of the NAM shows ridge winds gusting up to around 30-
35 kts until around 13/01-02Z which may result in some LLWS and
turbulence concerns. Precipitation chances for areas closer to
the OR border look to taper off around 13/03Z. -078
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$