Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/25/23
Area Forecast Discussion
National Weather Service Indianapolis IN
932 PM EST Fri Feb 24 2023
.Forecast Update...
Issued at 932 PM EST Fri Feb 24 2023
Brief period of 290K isentropic lift and moisture, increasing from
top down per lowering condensation pressure deficits and BUFKIT
soundings, support leaving chances for precip overnight. That said,
most of the obs over northern Illinois and Missouri, where the
current 30+ echoes are, were not revealing any precip reaching the
ground.
Latest ACARS sounding along with BUFKIT soundings suggest any light
precip will fall mostly as rain. Significant cloud cover should keep
slightly above freezing temperatures at bay and possibly slow rise
overnight.
&&
.Short Term...(This evening through Saturday)
Issued at 314 PM EST Fri Feb 24 2023
- Mostly cloudy Tonight; sprinkles, freezing drizzle or flurries
possible.
- Mostly Sunny and warmer on Saturday
Surface analysis early this afternoon shows a large area of cold
high pressure over the Great Lakes. This system was providing cold
northeasterly surface flow across Central Indiana. Aloft water vapor
showed a nearly zonal flow across the plains states and into the
Ohio Valley. A weak short wave was found over KS/OK, along with a
second wave over TN. The Tennessee system was producing some rain
across Arkansas and Tennessee, but this will remain south of Central
Indiana. The plains wave was failing to produce much other than a
few clouds. GOES16 shows partly cloudy across Central Indiana,
however some cold air advection stratus was found across the
northern third of Indiana. These clouds were remaining north of the
forecast area and as winds were becoming more northeasterly, they
are not expected to impact Central Indiana. Some mid and high clouds
were invading from the west and this was associated with the
previously mentioned weak short wave approaching from the plains.
The lower levels of the atmosphere remained quite dry as dew point
temperatures across the area were in the teens.
Tonight...
The surface high pressure system to the north is expected to
continue to progress eastward, allowing an easterly lower level flow
of dry air across Central Indiana. Meanwhile aloft the short wave to
the west is expected to progress across Indiana. GOES16 shows some
mid and high level clouds with this feature, but there is little in
the way of precipitation. Forecast soundings overnight continue to
show dry air within the lower levels and models suggest surface dew
points fail to get higher than the lower 20s. Mid levels become
saturated amid weak warm air advection ahead of the short wave, but
lower levels remain dry. HRRR suggests a weak wave of very light
scattered precip pushing across the area overnight. Given the dry
lower levels, confidence is low for any measurable precipitation.
However a freezing drizzle sprinkle or flurry cannot be ruled out.
Any pops that are included will be quite minimal. Dynamic forcing
from the quick moving wave appears to exit the area by 12Z, leading
to a return of subsidence. Given the expected cloud cover will trend
lows toward the upper 20s and lower 30s.
Saturday...
Models suggest the continuation of zonal flow aloft on Saturday as
weak ridging begins to build across the western plains. This once
again allows subsidence to return to Central Indiana. Forecast
soundings on Saturday reveal a dry column in the wake of the
departed short wave. Convective temperatures appear unreachable,
thus we will expect mostly sunny skies, with only the stray passing
high cirrus cloud aloft. Meanwhile at the surface, another area of
high pressure is suggested to reorganize over KY and TN, leading to
warmer westerly surface flow across Indiana. Thus highs in the upper
40s to lower 50s will be expected.
&&
.Long Term...(Saturday night through Friday)
Issued at 314 PM EST Fri Feb 24 2023
Temperatures throughout the long term period will be above normal
with highs oscillating from the 50s to 60s and lows from the 30s to
40s as a couple of systems move across the region.
The period will start out quiet as ridging passes through the region
aloft. An upper low will move in from the southwest and southern
plains reaching the Great Lakes region by early Monday. This system
will bring precipitation chances starting in the SW as early late in
the day Sunday due to isentropic lift along the warm front moving
northward. The surface low itself and the associated cold front,
which will have near definite rain chances with it, will enter the
forecast area more so during the day Monday. The best chances for
rain and storms will be from early morning Monday into midday with
slight chances of thunder embedded. Storm total QPF currently looks
to be about half an inch to an inch which shouldn`t cause many
issues in terms of flooding. The main story with this system will be
the increased gradient winds set to move in along and behind the
cold front. A LLJ, with a centroid of 60-70 kts at 850 mb will pass
overhead which should mix down to the surface from prior to sunset
throughout the rest of the day with surface winds potentially
getting to around 50 mph at times. Within storms, some stronger
winds could be embedded. Winds will drop some by monday night and
will further weaken through the day Tuesday.
Temperatures will dip some Tuesday behind the cold front but are
expected to rebound quickly by Wednesday as southern to southwestern
surface flow returns. A surface high will move in behind the early
week system, leading to a break in precipitation for midweek.
At the end of the period, there remains quite a bit of variability
between models thus leading to quite a bit of uncertainty. It does
appear that some sort of upper wave will bring precipitation chances
somewhere between the Great Lakes and Tennessee Valley during the
latter half of the week as well as slightly lower temperatures. Will
continue to monitor and see where models converge on solutions.
&&
.Aviation...(00Z TAF Issuance)
Issued at 536 PM EST Fri Feb 24 2023
Impacts:
- VFR flying conditions and winds less than 10 knots through
Saturday night
Discussion:
Good flying weather is expected through Saturday night under
the influence of high pressure over the Great Lakes. Mid and
high clouds will roll through in zonal flow well ahead of
the low pressure system looming off the Pacific coast.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...MK
Short Term...Puma
Long Term...KH
Aviation...MK
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
901 PM CST Fri Feb 24 2023
.UPDATE...
Issued at 901 PM CST Fri Feb 24 2023
Narrow band of fairly impressive looking virga we`ve been watching
the past couple hours associated with strengthening frontogenesis
centered in vicinity of 700mb, has eaten away at the very stout
dry layer. Noted a 5C temp gradient between DVN and ILX at 700mb
in the 00z soundings, with some somewhat steeper lapse rates
above that front on the ILX sounding.
This narrow, but rather intense, band of snow will lift north
across the area northern Illinois and northern portions of Lake
and Porter Counties over the next couple/few hours. Seeing some
near 40 dBz returns with this band over southeastern Cook and
northern Lake County IN, with KIGQ briefly reporting 1/4SM VSBY
under that band. Working on updating grids and forecast, but
certainly under the heavier portions of the band could see a quick
half inch of snow which will result in some accum on roads with
travel impacts.
- Izzi
&&
.SHORT TERM...
Issued at 105 PM CST Fri Feb 24 2023
Through Saturday night...
The upper-level pattern remains energetic and within a -PNA regime
with deep troughing entrenched across the Pacific coast of the US
and a rippin` upper-level jet stream across the central US (the
12Z DVN RAOB sampled 180kt of flow at 250mb). The only focus in
the short-term period is on a subtle vort max propagating within
broad upper-level southwesterly flow toward the Great Lakes. As
modest DCVA spreads across the Great Lakes this evening ahead of
the wave, expansive virga currently over Iowa will expand eastward
in tandem with thickening upper-level clouds. The low-level
airmass remains effectively parched (recent AMDAR soundings
sampled a ~7000 ft layer where the RH ranged between 15-35%
beneath upper-level cloud bases), though with time a few flurries
or even brief snow showers may break through particularly between
6 PM and midnight. For now, opted to maintain low-end PoPs
(15-20%) for snow showers generally along and north of I-88.
Meanwhile, modest WAA across the mid-Mississippi River Valley
should encourage a few showers to develop toward midnight,
particularly south of I-80. Precipitation type with any WAA-driven
shower may end up as a low-quality snow grain (in-cloud
temperatures hover between -9 to -10C), or even a patch of
freezing drizzle. At this point, coverage, longevity, and
intensity of precipitation does not seem nearly high enough to
lead to any impacts within either regime.
Outside the low-end chances for flurries tonight, there are no
weather concerns in the short-term period. Easterly winds will
gradually veer around the clock tonight and become west to
southwesterly tomorrow. Clearing skies and gradually increasing low-
level WAA will support warming temperatures with highs in the upper
30s to lower 40s.
Borchardt
&&
.LONG TERM...
Issued at 322 PM CST Fri Feb 24 2023
Sunday through Friday...
The main focus of the long term forecast period continues to be on a
wound-up storm system that will bring another round of soaking
rainfall to region, and potentially some thunderstorms and advisory
or near advisory-level winds as well.
Sunday looks quiet and unseasonably mild with low-amplitude ridging
in place. The action will be elsewhere as a meandering, closed-off
upper-level low currently wreaking havoc across California will
rapidly be propelled eastward as a digging trough over the Pacific
gives it a boot. Lee cyclogenesis will accordingly commence late
Sunday over the central Plains, with the resultant 975-980 mb
surface low eventually expected to track into southern Iowa and then
northern Illinois/southern Wisconsin on Monday in its occluding
phase. Unsurprisingly, this system will bring a handful of sensible
weather impacts to the region.
First, this system will draw a plume of rich Gulf moisture up to our
latitude, yielding precipitable water values that will likely fall
somewhere between 1 and 1.3 inches, which, like this past Thursday`s
system, would be record or near record values for this time of year.
This system should be a bit more progressive than Thursday`s system,
but precipitation should still get enough residence time to churn
out some decent rainfall totals across our forecast area given
the stellar magnitude of the forcing in play, and the ECMWF
Extreme Forecast Index for QPF being greater than 0.8 across our
CWA does keep our confidence relatively high that we`ll see
another rainfall event that would be considered anomalous for this
time of year. While we`re still a few days away, an early look at
medium range QPF suggests that at least half an inch of rainfall
appears likely to be seen across most or all of our CWA, and it`s
probable that some locations will pick more than an inch of rain
when all is said and done. While these totals on their own may not
be much cause for concern, the saturated soils and elevated river
levels in the wake of our recent rainfall leave us a little more
prone to seeing additional hydrological impacts from QPF amounts
of this magnitude at this time of year, so have put out a
Hydrologic Outlook to better highlight the potential for
additional river rises and localized flooding in our forecast
area early next week.
Secondly, there remains a decent signal that at least some meager
instability could sneak into at least our southern counties late
Sunday night into Monday, and there is a non-zero chance that this
instability could be surface-based. Forecast hodographs look
pretty gnarly given the nature of the shear profiles associated
with this wound-up system, but fortunately, the timing of when
thunderstorms would be most likely to occur appears that it will
come during the climatologically unfavorable late overnight/early
morning hours. The preceding precipitation within the leading
wing of warm air advection should also hamper the ability for even
a scant amount of true surface-based instability to be realized,
so am thinking that potential for severe weather to occur anywhere
in our CWA is quite low, but will continue to keep a close eye on
trends in forecast guidance to see if our messaging for the
thunderstorm potential needs to be adjusted at all.
Lastly, blustery to strong winds should be seen on Monday as low-
level pressure gradients compress in response to the approaching
low. There may be a relative lull in the magnitude of the winds in
the immediate vicinity of the surface low, but south of where the
low tracks, advisory-level gusts may be achieved, primarily as cold
air advection steepens low-level lapse rates and assists in the
transfer of some higher momentum flow down to ground level.
Things should dry out for Tuesday as high pressure fills the void
behind Monday`s system. The effects of cold air advection on the
backside of the system shouldn`t be too noticeable come the
afternoon hours on Tuesday as mostly clear skies should help
temperatures bounce back into the 40s, if not the 50s. A more
benign mid-level impulse will then zip into the Great Lakes
Tuesday night into Wednesday and bring us our next chance for
precipitation as we head into the middle of next week.
Ogorek
&&
.AVIATION...
For the 00Z TAFs...
Key messages:
* A few flurries possible this evening
* Low chance for MVFR cigs early Saturday morning
Radar presentation confirms that precipitation continues to
struggle to reach the ground due to a stout dry layer in the low-
levels. This lowers confidence in the terminals seeing any
snowflakes this evening admittedly. Felt prudent to maintain a
mention of flurries but pushed back the start time of the TEMPO by
one hour to 1Z to allow more time for saturation. Any snow that
does fall will be very light with little to no impact expected.
There exists a low chance for MVFR cigs to develop later tonight
into Saturday morning. For now have kept this period VFR but it
may be considered with later updates if confidence increases.
Winds remain out of the east this evening becoming very light and
veering westerly by daybreak before settling in to a
southwesterly direction later in the afternoon.
Petr
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Raleigh NC
925 PM EST Fri Feb 24 2023
.SYNOPSIS...
A cold front will settle south of North Carolina tonight and
Saturday, as cooler air extends into the area from the north. A
surface low will track along the front and shift off the southeast
coast through Saturday, bringing periods of light rain. Dry high
pressure will build in for Sunday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 925 PM Friday...
Primary change this evening has been to delay the onset of
measurable precip across northern sections overnight. The latest
surface analysis shows the frontal zone S of the state across SC,
and the parent high providing the source of cooler/dry air centered
over SE Ontario and nosing into NC. The initial batch of rain now
moving over our W and S sections is encountering a fairly deep (~ 7k
ft currently) dry subcloud layer, as noted on the 00z GSO sounding,
on RDU-area ACARS soundings, and by surface dewpoint depressions
that are still 40+ deg F over much of the area. This rain appears to
be largely driven by a very weak mid level perturbation passing over
the region, likely linked to subtle upper jetlets/speed maxima on
the S side of a large 170+ kt W-E jet streak to our N. Lower level
forcing for ascent, primarily deepening and strengthening upglide,
is projected to quickly ramp up overnight, although it will still
take a while to overcome the dry low levels, thus have delayed onset
of appreciable rainfall across the N for the rest of tonight, and
amounts areawide will still be low, despite likely pops across the
S. Expectations are that this dry depth will finally approach
saturation toward daybreak, and have retained the likely pops most
everywhere starting Sat morning, although the low dewpoint advection
will persist as the parent high drifts E into a better position to
allow drier air to advect into our area, and this could further
delay near-ground saturation in the N. Under overcast skies, temps
have been trending a bit warmer than forecast pace, so have made
appropriate adjustments, with lows of 39-47 N-S. -GIH
Earlier discussion from 250 PM: Afternoon surface analysis reveals a
1040 mb high pressure over Minnesota. The surface cold front, based
on ASOS/AWOS and theta-e analysis, is roughly across central SC and
northern GA. Dewpoints have further mixed out from the morning
update, ranging from the mid to upper teens in the northern Piedmont
and northern Coastal Plain to the 20s/30s over the southern
Piedmont, Sandhills, and southern Coastal Plain. The MET/HRRR were
the best guidance in picking up on this drier air, but still not low
enough in most cases. This along with temperatures in the upper 60s
to upper 70s have lowered RH levels in the 10-20 percent range. This
led to a brief period earlier today of some increased fire danger
but as gusts have decreased to 10-20 mph, the fire danger has
largely diminished.
Dewpoints are expected in most of the guidance to recover tonight as
precipitation overspreads the area with moist advection. Speaking of
the precipitation, 12Z guidance and the high-resolution CAMs roughly
show two potential waves to the rain tonight into early tomorrow.
While there is not a lot of upper-forcing (albeit some weak mid-
level disturbance tracking east-southeast overnight across southern
NC/northern SC), isentropic ascent atop the surface boundary in the
295-305 K surfaces will promote scattered to widespread light
rain/drizzle overnight and toward daybreak. The first wave appears
to track east-southeast from the southern Piedmont into the
Sandhills tonight tied to more mid-level ascent, while a secondary
batch may move east-northeast overnight across most of central NC
associated with the lower-level WAA, centered around 800 mb. Given
the dry air in place and seen in forecast soundings, the onset may
be slower across the Triangle and northeast Piedmont to northern
Coastal Plain. Precipitation amounts will range from a few
hundredths in the northeast to a tenth to fifteen hundredths in the
southwest. Overnight lows will range from the upper 30s to low/mid
40s from NE to SW.
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 255 PM Friday...
The weekend will start as a cool, dreary and rainy Saturday and
persist through the day. Central NC will situated underneath weakly
perturbed zonal flow between a parade of shortwaves rotating through
the northern CONUS and a abnormally strong mid-level ridge residing
over the eastern GOM (+3 to +4 sigma above normal). Moderately
strong surface pressure will be positioned over the Northeast
Saturday morning extending down through the southern Mid-Atlantic
behind the fropa on Friday. This cold front will remain south of the
region as strengthening isentropic ascent through a deep lower
tropospheric layer overrides the surface front bringing low clouds
and precipitation to a majority of the region. Although the surface
high will be weakening as it slowly shifts eastward on Saturday,
diabatic cooling/moistening of the dry continental airmass will lock
in an in-situ CAD regime through the day Saturday. Isentropic flow
will continue to deepen/strengthen throughout the day leading to
light rain and drizzle until lower tropospheric winds shift from a
westerly direction Saturday evening. This will shift the
precipitation eastward and off the coast by late Saturday evening.
Guidance is uncertain on the level of clearing that will occur as
winds shift out of the west late Saturday into early Sunday morning.
Point soundings indicate a drying in the mid-upper levels after 06z
with a residual low-level moisture layer within the in-situ CAD
airmass. This pattern seems ripe for some patchy fog development,
whether it originates as radiation fog within the in-situ CAD
regime, or a lingering low stratus layer that slowly lowers to the
ground creating patchy fog. Have opted for the climatologically
favored areas across the northwest Piedmont and portions of the
northeast Piedmont to introduce patchy fog into the forecast. Low
clouds and multiple rounds of light rain and drizzle during the day
will lead to a small diurnal curve with highs in the 40s and lows
falling into the low/mid 40s to upper 30s. .
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 220 PM Friday...
...Unseasonable Warmth Continues...
...Potentially Wet and Unsettled to Close the Work Week...
Sunday: The mid/upper level ridge centered over the MS River Valley
will begin to move into the region from the west. At the surface,
the CAD regime in place to start the day will gradually scour out
through the afternoon as the synoptic scale quasi-stationary surface
front stays south of the area. Despite W-NWLY flow aloft, there will
be considerable cloudiness, especially during the 1st half of the
day as a persistent plume of enhanced mid/high level moisture
streams atop the residual moist shallow CAD layer. By the afternoon,
could see brief intervals of sunshine, which will be influential in
just how much quickly temps recover/warm. While isolated isolated
sprinkles and/or light rain is possible early in the day before the
low-level moisture mixes out, it should largely remain dry. Highs
Sunday afternoon ranging from lower 60s NW to lower 70s south.
Sunday night through Monday: Well removed from the upper
forcing/dynamics associated with a de-amplifying compact closed
upper low/shortwave trough ejecting NEwd from the southern US Plains
to the Ohio Valley and Lower Great Lakes region, the passage of a
warm front will bring a chance of scattered WAA showers late Sunday
night, but mostly during the day Monday, followed by more in the way
of isolated shower coverage Monday evening/night with the passage of
the attendant cold front. With the stronger forcing passing well
north of the area and with only modest moisture transport into the
region, it`s not surprising to see the latest round of 12z/24 model
guidance trending lower with QPF amounts across central NC, down to
a tenth of an inch or less and generally confined to northern
portions of the forecast area. Expect mild/warm temperatures within
the WAA regime ahead of the cold front. Breezy with highs Monday
ranging from near 70 north to upper 70s/lower 80s south.
Tuesday through Wednesday: A weak, transitory surface high
traversing the mid-Atlantic region will quickly move offshore early
Wednesday, which will allow the front to our south to retreat as a
warm front Wednesday afternoon. While temperatures will cool
slightly behind the cold front, flat/low amplitude ridging aloft
will continue to promote above normal temperatures. Highs ranging
from lower/mid 60s north, to lower/mid 70s south. Tuesday night will
be coolest night this stretch, with lows in the mid/upper 30s north
to lower/mid 40s south.
Wednesday night through Friday: The latter half of the work week
looks increasingly wet and unsettled with periods of rain/showers
ahead of robust mid/upper level trough that is forecast to traverse
the southern CONUS. Rain chances return Wednesday night with another
batch of WAA showers ahead of a cold front that will bring
additional rain chances during the day on Thursday as the front
potentially stalls out somewhere INVOF the Carolinas. Thereafter,
the exact location of this front and subsequent associated waves low
pressure that could potentially develop along the front as the
aforementioned strong mid/upper level trough moves into the region
is the source of high model spread and uncertainty. Until these
discrepancies can be resolved, cannot speak in great detail about
specific weather impacts aside from high confidence in additional
periods of rain and/or shower extending into the day on Friday.
Given the strength of the upper trough and strong kinematic wind
fields, will need to monitor the potential evolution of a convective
threat across the Carolinas during the Thursday through Friday
period.
Temperatures will continue to be well-above normal ahead of the
front with highs in the 70s and overnight lows remaining well above
freezing.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 637 PM Friday...
There is high confidence that VFR conditions will hold through ~06Z
tonight. Beyond 06Z however, conditions will rapidly deteriorate as
enhanced low-level moisture and light rain surges across central NC.
Associated ceilings are expected to drop to MVFR between ~08 and 12Z
before further dropping to IFR through late Saturday morning
(earliest at KINT/KGSO; latest at KRWI). Latest guidance is in
pretty good agreement that sites will possible experience periods of
LIFR ceilings from Saturday afternoon through the end of the 24 hr
TAF period. Confidence in LIFR ceilings developing is highest at
KFAY/KRDU where the deeper moisture will be present. Any lingering
light rain should push east of the area by ~22Z, but IFR/LIFR
ceilings will persist into Saturday evening.
Looking beyond 00Z Sunday: Sub-VFR ceilings and visibilities with
low stratus and fog may develop Sunday morning. Dry weather and VFR
conditions should return by Sunday afternoon, with the next chance
for restrictions and rain returning Monday afternoon/evening with a
cold front. Confidence is highest in these chances for the southern
terminals. Ahead of the cold front Monday afternoon, winds could
gust to 30 kt out of the south-southwest. Dry weather and VFR
conditions will return for Tuesday and should continue into
Wednesday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Kren/Hartfield
NEAR TERM...Hartfield/Kren
SHORT TERM...Swiggett
LONG TERM...CBL
AVIATION...Luchetti/Marcus/Kren