Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/20/23
Area Forecast Discussion
National Weather Service Indianapolis IN
1009 PM EDT Sun Mar 19 2023
.Forecast Update...
Issued at 1009 PM EDT Sun Mar 19 2023
Little changes made to the short term forecast this evening as
everything seems to be going on track. Current surface analysis
shows an area of high pressure centered over the Gulf Coast states
with weak southwest flow across Central Indiana. Satellite imagery
shows clear skies across the entire Ohio Valley this evening, which
will lead to optimal conditions for radiational cooling through the
night. All locations have dropped below freezing as of 10 PM and
will continue to plummet into low 20s by Monday morning.
Minor tweaks made to the forecast for tomorrow. Southwest flow
pattern persists with high pressure south of the region. Short term
guidance indicates deep mixing up to 4 kft agl by tomorrow
afternoon. RAP forecast soundings show mixing into a dry layer
located just above the surface, which will likely result in dew
point and RH values well below NBM guidance during peak heating of
the day tomorrow. This change brings min RH values tomorrow
afternoon into the mid 20s to mid 30s across the entire region.
These patterns also produce highs a few degrees above guidance, so
nudged high temps up to the low 50s for much of the region. Deep
mixing will also lead to stronger winds aloft mixing down to the
surface. Highest wind gusts looks to be across the northwest half of
the forecast area, closer to the stronger low level jet. Expect wind
gusts around 20-30 mph Monday afternoon, with the highest gusts
closer to the Lafayette area. These dry and breezy conditions may
pose a slight fire weather threat during the afternoon hours
tomorrow; however the risk is not high enough to warrant the
issuance of any products or alerts at the moment.
&&
.Short Term...(This evening through Monday)
Issued at 251 PM EDT Sun Mar 19 2023
Quiet and warmer weather continued across central Indiana this
afternoon. The March sun was melting away what snow cover there was
across the forecast area. Cumulus across the southern forecast area
were gradually diminishing as warmer air aloft moves in.
Cumulus will continue to gradually dissipate for the remainder of
the afternoon. Temperatures will still be below normal but warmer
than Saturday`s readings.
Tonight, quiet weather will continue as surface high pressure
(centered south of the area) remains in control. This will keep
winds from going calm and place some limit on radiational cooling.
However, it will still be cold for two-thirds of the way through
March. Blended guidance still looks a bit warm, so will cut some.
Lows will be around 20 into the lower 20s.
On Monday, southwest winds will bring in warmer air. High pressure
will still be in control, but a cold front will be relatively not
that far to the northwest of the area. As a weak upper wave
interacts with this, some mid and high cloud will pass through,
especially north.
Winds will increase aloft with this setup, and some momentum
transfer will occur to the surface. Winds will gust into the 25 to
30 mph range.
Highs will be in the upper 40s to around 50 thanks to the warm
advection.
&&
.Long Term...(Monday night through Sunday)
Issued at 251 PM EDT Sun Mar 19 2023
* Moderation Through Thursday...Then Near-Normal Temperatures
* Potential for Heavy Rain/Flooding Within Thursday-Friday Timeframe
Monday Night and Tuesday...
A zonal ridge will oversee the return flow, yet still-dry, side of
the current dome of Canadian high pressure...as it drifts eastward
across roughly the eastern half of the CONUS. Scattered clouds are
expected over the northern tier Monday evening as the region catches
the southern edge of a weak wave crossing the Great Lakes. Bigger
story will be a 998 mb surface low over western Kansas Tuesday, and
the corresponding gradient and south-southwesterly flow off of the
western Gulf of Mexico...that will begin to re-moisten the column.
High/mid clouds will thicken top-down from southwest to northeast
from pre-dawn to midday Tuesday...with stratus expected to arrive
during the afternoon. Mainly southernly winds will gust as high as
20-25 mph for much of these two periods, with organized rain
possibly reaching western counties by early Tuesday evening.
Temperatures will continue their moderating trend, with lows around
30F and another seasonably mild day Tuesday with readings peaking in
the mid-50s for most locations.
Tuesday Night through Friday...
A generally unsettled pattern will prevail through the rest of the
workweek as several waves pass near/over central Indiana. Guidance
is continuing to show roughly three phases of rain potential. First
is a rather light rainfall over Tuesday night-Wednesday courtesy of
a weakly-forced, yet rather broad ribbon of Gulf moisture...with as
much as 0.25-0.50 inches of rain across southern Indiana...as the
region basks in the mild warm sector breezes of the storm system
passing well to our northwest.
Next would be an overall lull in organized rain as the nearly-
stationary frontal zone between the departing system and next low
pressure over Kansas drags into the northwestern Midwest around the
late Wednesday/early Thursday timeframe. Gusty southerly winds will
serve to steadily recharge precipitable water values across our CWA
in mainly the 1.00-1.50 range...as a rather narrow axis of greatest
deep moisture likely extends from the Ozark Plateau eastward into
the Midwest - near/north of the I-70 corridor. Lack of forcing
should translate to overcast conditions with occasion light rain/
drizzle. Although a few ensembles suggest the potential for
moderate rainfall, especially towards our northwest zones which
should be closer to the slowly approaching boundary.
The long term`s greatest concern then comes through the late work
week when adequate forcing should arrive...between the slowly-
crossing front as well as embedded mid-level PVA...to produce
moderate-heavy rainfall over at least parts of the region.
Additional rainfall would potentially include greatest 12-hour
totals of 1.00-3.50 inches...with the heavy rainfall threat
transitioning from northern to southern counties through the late
week along with the boundary`s passage. Concerns for river and
areal flooding would be valid should this potential be realized,
although guidance so far is suggesting any late-week rains over 2.50
inches should not be widespread. At least isolated thunder cannot
be ruled out amid these heavier rains, with much of the region
progged to fall on the warm side of the boundary through at least
late Thursday, with dewpoints expected to approach 60F over southern
portions of Indiana. Temperatures should trend from above normal to
near normal through Friday.
Saturday through Sunday...
The upcoming weekend should feature perhaps 2-3 periods of mainly
dry weather with rather weak high pressure expected to slide across
the Great Lakes as the departing system tracks through the
Northeast. The next storm system, probably back to a track to our
northwest...will bring chances of warm frontal and/or warm sector
rain by the end of the long term...as south-southwesterly flow
returns ample deep moisture. Indianapolis` normal max/min through
the long term is 55/36.
&&
.Aviation...(00Z TAF Issuance)
Issued at 727 PM EDT Sun Mar 19 2023
Impacts:
* VFR conditions expected through the next day
Discussion:
High pressure centered south of the region will keep conditions dry
and calm over the next day across Central Indiana. Subsidence under
the high tonight will result in mainly clear skies across the entire
region. Winds will diminish after sunset as low level mixing shuts
off and the pressure gradient remains weak. High pressure shifts
eastward tomorrow with southerly return flow increasing through the
region. Southwesterly Low level jet increases to around 25 kts
Monday afternoon. Expect steep lapse rates within the boundary layer
and mixing up into the low level jet to result in gusty winds up to
20 to 25 mph late Monday morning through Monday evening.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...CM
Short Term...50
Long Term...AGM
Aviation...CM
Area Forecast Discussion
National Weather Service Marquette MI
742 PM EDT Sun Mar 19 2023
.SHORT TERM...(Through Tonight)
Issued at 318 PM EDT SUN MAR 19 2023
Water vapor imagery and RAP analysis show that the deep mid-level
low that brought the wind and LES to the area yesterday is now in
southern Quebec. A shortwave noted dropping se across Manitoba and
northern Ontario is the next feature of interest for the short term.
Ahead of this feature, a dry waa regime is occurring across the
Upper Great Lakes today. Sharper 850mb temp gradient running vcnty
of the eastern shoreline of Lake Superior combined with some
moisture off of the lake has supported some -shsn/flurries across
the lake in Ontario. Otherwise, the dry air mass has allowed for
abundant sunshine across the fcst area today, and temps have risen
into the 30s as of 19z. A few locations are around 40F. Relatively
tight pres gradient btwn high pres centered over se OK and a cold
front in northern Ontario associated with the aforementioned
shortwave is resulting in a breezy day, especially on the Keweenaw.
Winds at KCMX have been gusting to around 40mph for much of the day.
Cold front in northern Ontario will sweep s into Upper MI tonight.
Observations upstream vcnty of the cold front reveal stratocu and
some -shsn. As the cold front drops across Upper MI late evening
thru early Mon morning, convergence along the front combined with
850mb temps around -10C over Lake Superior should further aid the
sct -shsn/flurries that are currently occurring vcnty of the front.
Nothing more than schc/chc mention seems appropriate given that the
shortwave passes by to the n of the area. By 12z Mon, 850mb temps
will be down to around -14C across northern Lake Superior, and a
marginal for LES -12C across the southern part. Result may be some
additional post frontal flurries/-shsn under developing northerly
low-level flow. Expect min temps tonight in the mid teens to mid 20s
F.
.LONG TERM...(Monday through Sunday)
Issued at 338 PM EDT SUN MAR 19 2023
Ensemble means are overall indicating near normal temps for the
extended fcst period, although a couple of ensembles (i.e. the GEFS
and GEPS) are expecting some above normal temps near the end of the
fcst period. Moving into Monday, expect light LES showers to
continue over the N/NE snow belts, particularly over the central and
west as the weak cold front continues towards Lower MI. With low
level clouds continuing throughout the day, mid level clouds moving
in overhead, light snow showers/flurries occurring across the area,
and very weak CAA from the north, I dropped highs down a bit from
the previous fcst, thinking that most of the area will stay below
freezing tomorrow save for the south central. That being said, with
the higher sun angle, I wouldn`t be surprised if we saw a little bit
of snow melt across most of the area. As we head into the overnight
hours, expect some light snow showers to move over the interior west
near WI and the south central early, with possibly some light
LES/flurries occurring over the NE snow belts save for areas west of
the Keweenaw as light winds veer with time. There may be some breaks
in the cloud cover over the UP Monday night as the mid level cloud
cover leaves and the low level lake-effect clouds erode across the
area. While I decreased temps a bit from the previous NBM fcst,
should enough cloud cover erode away we may see lows bottom out to
the negative single digits in the interior west and single positive
digits in the interior central and east (the NBM10th percentile
highlights this quite well).
As we move into Tuesday, a low pressure system over the Central
Plains begins to lift towards MN. As it does so, guidance suggests
that an area of weak isentropic lift moves through the UP late
Tuesday afternoon ahead of the warm front of the low. While only a
dusting to a few tenths of an inch of snowfall is really all that`s
expected, a band of some light to locally moderate snowfall could be
seen along this band, which could cause some minor visibility
concerns if driving. Once the band lifts out of the area, expect a
quick break in the precip before the main warm front moves into the
area late. Compared to yesterday`s fcst, its seems that the timing
of the low has slowed ever so slightly, allowing for colder air to
arrive quicker over the UP. However, not really expecting snow
totals to increase as overall QPF from this system seems to have
decreased a little since yesterday. Overall, still expecting
anywhere from a dusting to a wet inch in the south central, 2 to 4
inches of wet snowfall in the Keweenaw, and 1 to 2 inches everywhere
else in the UP. Most guidance has a majority of the area (save for
maybe the Keweenaw) transitioning over to rain for a few hours
before the front completely passes through the area. However, I do
have some doubts with that as model guidance is showing nearly
unstable lapse rates near the sfc once the warm front passes
through, and given the cloud cover remaining over the area and the
mostly saturated profile (save for in the lowest levels), I have
some suspicion that those lapse rates aren`t going to be achieved.
Therefore, I lowered temps Wednesday with the NAM12km, as I think it
nudges the fcst in the right direction and keeps highs mainly in the
upper 30s (although some spots like in the south central and the
south wind downslope areas could get up to the low 40s). Thus, I
think that some spots in the north central, west, and Keweenaw may
stay snow for the whole event, although I do think temps will be
warm enough to bring at least some level of snow melt across the
entire area during the day Wednesday. The cold sector of the low is
set to move into Upper MI Wednesday evening; some rain and snow
showers could be seen ahead and along the cold front.
Once we move into Wednesday evening, there is quite a bit of model
spread as to what will happen. One set of solutions has precip
developing along a shortwave low moving through the Ohio Valley,
whereas another solution could be a strong wrap-around low that
lifts through Lower or Upper MI. Should the former solution be true,
then we will likely stay mostly precip free; should the latter be
true, we could see some additional snowfall, most likely over our
south central and east. Models do reconverge and have high pressure
settling over us Thursday night through Friday, which could bring
nice sunny skies over us, probably creating some more snow melt
across the area. Moving into this weekend, medium range guidance
suggests that a strong low pressure will develop over the SE US or
Southern Plains and lift northeast towards the Great Lakes. Should
low trend more westward, like in the 12z Euro, we may see some wet
snowfall, especially over our south central and east. Past the end
of this fcst period, ensemble means hint at temps averaging below
average, meaning we could see a chillier end to March and start to
April.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 739 PM EDT SUN MAR 19 2023
Ahead of a cold front currently dropping s thru northern Ontario,
very dry air will remain over the area along with gusty w to sw
winds. As a result, VFR conditions will prevail at IWD/CMX/SAW
into the evening hrs. Winds will gust 20-30kt, strongest at CMX.
Winds will probably decouple at SAW this evening, leading to a
period of LLWS. As the cold front passes across the area tonight,
MVFR cigs will set in and winds will diminish, beginning first at
CMX around 04z. There may be -shsn/flurries with fropa at any of
the terminals, but don`t expect vis to drop any lwr than MVFR if
-shsn occur. MVFR cigs will then prevail at all terminals thru
Monday. A few flurries will be possible at times. &&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 355 PM EDT SUN MAR 19 2023
W to WSW`rly winds of 20 to 30 knots, with a few gale force gusts up
to 35 knots over the western lake near the Keweenaw and Porkies
early this evening diminish to generally 20 knots or less behind a
cold front dropping down from northern Ontario tonight. Expect the
light winds to continue across the lake until Tuesday, when a low
pressure lifting from the Central Plains towards the western lake
brings E`rly winds of 20 to 30 knots across the western lake, with a
few gale force gusts up to 35 knots being possible near the MN
shoreline. As the low approaches the western lake Tuesday night,
expect the winds to slowly veer with time, weakening over the
western lake while increasing to SE`lry winds of 20 to 30 knots
across the eastern half late; some gale-force gusts up to 35 knots
may be possible Wednesday morning, but I have my doubts due to the
WAA regime. Once the low gets through the lake by Wednesday night,
expect the cold air behind it to bring NW`rly winds of at least 20
to 25 knots across the area Wednesday night into Thursday.
Afterwards, expect winds to remain light at 20 knots or less as high
pressure builds in Thursday night into Friday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning until 8 PM EDT /7 PM CDT/ this evening for LSZ162-
242>244-263-264.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...TAP
AVIATION...Voss
MARINE...TAP
Area Forecast Discussion
National Weather Service Pittsburgh PA
649 PM EDT Sun Mar 19 2023
.SYNOPSIS...
High pressure across the Upper Ohio Valley and Allegheny
Mountains will result in cool, dry weather to start the work
week. A low pressure system moving across the Great Lakes on
Wednesday will bring the next chance of rain to the area.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
645 PM Update: Latest radar and satellite imagery shows that
shower activity has diminished as high pressure builds across
the forecast area and drier air has worked into the low/mid-
levels. Breezy conditions remain, but should subside soon after
sunset between the pressure gradient relaxing and PBL
decoupling. Otherwise, forecast remains on track.
Previous...
Recent mosaic radar imagery suggests ongoing lake enhanced snow
showers in conjunction with a crossing thermal trough, evident
via 700mb RAP analysis. Building sfc high pressure and departing
shortwave ascent should eventually diminish precipitation
chances north of I-80 through this afternoon. That dry advection
should also help dissolve the existing stratocu cloud layer
across northern zones, with a lingering scattered cloud deck
near 5,000ft expected through early eve. Wind transport from
that level, roughly ~700mb, will maintain wind gusts near 15-20
mph today before decoupling returns light wind after sunset.
Otherwise, below normal temperature will continue today, with
highs in the upper 20s to 30s, ~10 to 15 degrees below average.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Guidance continues to signal a return to a quasi-zonal flow on
Monday and temperature should slowly moderate back toward
climatological norms. Surface high pressure will support dry and
mostly sunny conditions, with southwesterly wind gusting
10-15 mph. Tuesday will feature similar conditions, though a
digging western CONUS closed low should promote subtle height
rises across the eastern CONUS and increase high temperature by
a few, additional degrees. For context, the average high/low
temperature this time of the year for PIT is 50F/30F.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Rain will likely return Wednesday as a Colorado low ejects
northeast into the Midwest and moisture within the Gulf of
Mexico drives north. Drier air, from the lingering ridge, and
weak ascension should limit precipitation amounts to less than a
quarter of an inch across the region.
The potential for heavier precipitation, based on current model
trends, will likely occur Friday into Saturday as a new low
pressure system develops in the Great Plains and engages with a
stationary boundary positioned from the Mississippi River
Valley into the Ohio River Valley. A swath of heavy rain could
start just west of the Ohio River Valley and migrate south into
the southern Appalachians as the ridge axis over the East Coast
weakens. The NBM currently projects 40-50% probabilities of QPF
exceeding 0.50 inches in 24 hours during this time period;
15-30% for over 1.0 inch. The Weather Prediction Center has
issued a Marginal Outlook for Excessive Rainfall for Day 5 to
highlight the potential of high water if convective showers
remain somewhat-stationary and robust.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR is expected through the TAF period as high pressure builds
across the Ohio and Tennessee Valley region. W-SW wind gusts
will diminish after sunset as mixing decreases, though speeds
will remain near 10 kt through the period.
.OUTLOOK...
VFR is expected through Tuesday under high pressure.
Restriction potential in occasional rain returns Wednesday
through Friday as a series of low pressure systems track across
the region.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Brown
NEAR TERM...05/Brown
SHORT TERM...05
LONG TERM...05
AVIATION...WM
Route 62. As mentioned in the previous forecast discussion, unsure
how precipitation on Tuesday will impact wind speeds, so held off on
any other wind-related headlines, though some Wind Advisories may
ultimately be needed across the Mojave Desert.
Temperatures will range from 10 to 20 degrees below seasonal
averages through the remainder of the forecast period. Otherwise, an
active pattern persists.
&&
.HYDROLOGY...Minor-to-moderate flooding from higher-than-normal
streamflows are forecast to continue within the Meadow Valley Wash
through the week due to recent rain, regional snowmelt, and
controlled releases from the Eagle Valley Dam in preparation for
next week`s storm system. Forecast precipitation across the southern
Great Basin next week will only act to exacerbate the ongoing
flooding in Lincoln County.
&&
.AVIATION...For Harry Reid...Light southeast winds to pick up from
18z on with gusts 20-25kt through the afternoon. Occasional light
showers and ceilings of 6-8kft can be expected through mid to late
afternoon. Visibilities should generally remain VFR. Winds to
decrease by 07z, remaining light overnight with improving ceilings
and decreasing showers.
For the rest of southern Nevada, northwest Arizona and southeast
California...Breezy south winds will persist as another storm system
affects the region. Winds will be strongest at KBIH, with gusts
around 25-35kt. Elsewhere, gusts should be more in the 15-25kt
range. Broken to overcast skies and sporadic showers will also
accompany the storm system, though visibilities generally look to
remain VFR and ceilings in the 6-8kft range. The one exception is
KBIH, where ceilings will hover between 3-5kft through the
afternoon. Winds to become light toward sunset with improving sky
conditions and decreasing rain chances.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Varian
HYDROLOGY...Pierce
AVIATION...Austin
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