Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/15/21
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
743 PM EDT Thu Oct 14 2021
.AVIATION...
Widespread shower and thunderstorm activity along the cold front has
cleared the forecast area to the east. Post frontal winds have been
relatively weak at 10 knots or less. Modest surface based cold
advection tonight with lack of sharp lower tropospheric temperature
inversion will allow for rapid improvement of ceiling heights to VFR
during the first 1-2 hours of the TAF period. Moist surface
conditions will likely result in shallow ground br/fg and MVFR
ceilings during the late evening. Frontogenesis and associated
moisture advection leads to prevailing shower activity between 15-22Z
Friday.
For DTW...Prevailing rain showers with IFR expected 15-22Z Friday.
.DTW THRESHOLD PROBABILITIES...
* High for ceilings aob 5000 feet late tonight and Friday.
&&
.PREV DISCUSSION...
Issued at 409 PM EDT Thu Oct 14 2021
DISCUSSION...
Linear convection has organized along a line from Cass City to
Fowlerville with modest rainfall rates. So far observations have
come in with minimal wind (peak 20KT at MBS) given some degree of
inhibition within the boundary layer. EMC RAP mesoanalysis depicts
broad area of 800 J/kg of DCAPE amongst reservoir of 500-1000 J/kg
of SB/MLCAPE. EBS is there to preserve mature updraft structure (40-
50 knots) and expect several strong structures to expand further
south over the next several hours until the surface front makes
further inroads and diurnal enhancements fade with sunset. Weak
inversion/capping south of M-59 is expected to soon erode for the
southern half, unlocking some additional buoyancy by the time the
line arrives. Lapse rates remain meager, suppressing updraft speeds.
Based on orientation of wind shifts relative to radar thus far,
convection appears mainly coincident with the frontal slope. The pre-
frontal showers never really materialized earlier today, thus
further trimmed near-term Metro area PoPs to align with ongoing
convection.
It will take some time for the frontal slope to clear SE,
particularly south of I-94. An embedded shortwave impulse is
forecast to lift through overnight providing another opportunity for
precip. Given the elevated and shallow nature depicted via forecast
soundings, nocturnal thunderstorm activity will be limited. Large
temperature gradient develops overnight with clearing skies and
upper 40s to near 50F for northwestern locations while lingering
cloud cover and delayed FROPA keeps overnight lows in the upper 50s
to near 60F for the Metro region.
The axis of the aforementioned upper trough will tilt meridionally
on Friday bringing stronger jet energy and notable DCVA to the Great
Lakes. Plenty of available moisture to work with in the mid-upper
levels from the cooled airmass frontal wake. Wavy low-amplitude
shortwave height field suggests numerous rounds of showers and
perhaps a few embedded thunderstorms, predominantly during the PM
hours on Friday. Surface low approaches Friday night amongst
increasing deformation forcing for a persistent period of lift.
Sensibly cooler conditions arrive, approaching seasonal normals,
especially along/north of I-69. H8 temp trends drop into the low
single digits Friday night highlighting the degree of cold advection
and veering northwesterly flow. Saturday will be the chilliest day
(highs stuck in the 50s) with dwindling shower chances as the day
progresses. More cohesive NW flow with steep BL lapse rates help
bring a period of gusts in the 20-30 mph range. Lake Michigan
moisture flux will maintain ample cloudiness if not a few lake-
effect showers.
Upper level confluence ensues Sunday through Tuesday supporting a
period of drier weather. Minor height rises hint at a gradual
warming trend back toward climatological normals by mid-week with
increasing ridge amplitude across the Midwest. Stacked low brings
rain back by Thursday with increasing southwest flow.
MARINE...
Ongoing passage of a cold front has and will continue to produce a
line of showers with embedded thunderstorm activity that will sweep
across the Great Lakes through the evening. The last of the activity
will linger across Lake St. Clair and Lake Erie late this evening.
Wind direction will veer more westerly following the passage of the
front as winds remain light. A low pressure system will then move
northeast from the Ohio Valley through Lake Erie on Friday which
will push a stronger cold front across the Great Lakes later on in
the day. This system and front will produce widely scattered to
numerous showers with embedded storms throughout Friday, lasting
into Saturday morning. A much better lake response will come with
the push of cooler air behind the front as wind direction veers
northwesterly. Sustained winds nearing 20 knots looks likely across
Lake Huron on Saturday, with gusts around 25 to 30 knots. Small
Craft Advisories will be possible for the nearshore zones on
Saturday.
HYDROLOGY...
Showers and thunderstorms are on-going along a cold front dropping
through Lower Michigan. More substantial and widespread rainfall is
expected on Friday as an area of low pressure skirts past eastern SE
MI. Similar available moisture aloft on Friday compared to today,
but better vertical distribution and longer duration forcing will
produce between 0.50-1.25 inches of rainfall by Saturday morning.
The highest totals are expected across the southern four counties.
Max rainfall rates generally remain below a quarter of an inch
minimizing impacts to ponding along roadways, poor drainage, and low-
lying areas.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....CB
DISCUSSION...KK
MARINE.......AM
HYDROLOGY....KK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Green Bay WI
959 PM CDT Thu Oct 14 2021
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Friday
Issued at 223 PM CDT Thu Oct 14 2021
The latest RAP analysis and satellite/radar imagery show low
pressure spinning across northeast Manitoba and an occluded/cold
front moving east over the lower Peninsula of Michigan. Within a
shallow, colder airmass, a large area of stratus has made little
progress to the east across northwest and north-central Wisconsin
so far today. The rest of the region has seen clearing skies as
mid-level clouds have exited east with the front. Forecast
concerns mainly revolve around cloud trends and very light precip
chances through Friday.
Tonight...The low pressure system over south-central Canada will
lift northeast towards Hudson Bay while the occluded/cold front
will move over the eastern Great Lakes. Meanwhile, weak high
pressure will build into the state from the central Plains. As the
low pulls away, the low stratus deck over Minnesota and northwest
Wisconsin will lift north with the low, but still graze north-
central Wisconsin. Other mid-level clouds will also stream
overhead from the southwest ahead of the longwave trough. The
combo of clouds and winds should prevent tanking temps at the cold
spots and any risk of frost. Lows will range from the upper 30s
to near 50 by Lake Michigan.
Friday...The upper trough will continue to move east and spark a
weak surface wave along the old cold front positioned across the
Ohio Valley to the eastern Great Lakes. Northeast Wisconsin will
be on the back edge of the precipitation generated from this
surface wave. Most precip will remain southeast of the region as a
result, but its possible a few sprinkles or very light shower
could fall out of a mid-deck in the afternoon over northeast WI.
Areas further west should enjoy more in the way of sunshine.
Temperatures will be several degrees cooler than today, and range
from the middle to the upper 50s.
.LONG TERM...Friday Night Through Thursday
Issued at 223 PM CDT Thu Oct 14 2021
Models continue to advertise a progressive mean flow across the
CONUS into early next week, before the pattern begins to slow and
amplify mid to late week. One upper trough departs the Great Lakes
early this weekend, to be replaced by a weakening upper ridge to
start the work week. Other than a very small chance of light
showers over far east-central WI Friday evening, a dry stretch of
weather is expected through at least Tuesday. Models then struggle
with the eastward movement of a mid-level shortwave trough mid-
week which brings low confidence on when to bring precipitation
chances back into the forecast. Temperatures will settle closer to
normal Friday into Saturday, but then return above normal through
Wednesday.
Friday night and Saturday...
A small part of east-central WI may still be clipped by light
showers Friday evening as a surface wave rides northeast along a
frontal boundary to our east and the upper trough moves across WI.
Behind these systems, partly to mostly cloudy skies are expected
for the rest of the Friday night with enough of a pressure
gradient to prevent much in the way of frost formation even as
temperatures drop into the middle to upper 30s over northern and
central WI. Min temperatures over eastern WI to drop into the
lower 40s. Increasing sunshine is forecast on Saturday as the
trough pulls away from the region. A ridge of high pressure to be
situated over the central CONUS, but northeast WI to still be in a
northwest flow aloft. 8H temperatures to be around +2C, thus
temperatures will be closer to normal which would be a switch from
the mild conditions so far this month. In addition, gusty west-
northwest winds will make it feel cooler.
Saturday night and Sunday...
The surface ridge axis is expected to reach the Upper Midwest
Saturday night, bringing clear skies to northeast WI. Winds are
not forecast to completely decouple overnight, so the question
becomes on how extensive any frost may become. North-central WI
would be most vulnerable with min temperatures in the lower to
middle 30s. Other parts of far northeast and central WI should
drop into the middle to upper 30s. A Frost Advisory may eventually
be needed. Min temperatures for east-central WI to hold in the
lower 40s. Plenty of sunshine can be expected across the region on
Sunday as the surface ridge to move overhead by the afternoon. We
will still have a west wind of 10 to 15 mph, but with the onset of
WAA, look for max temperatures to rebound mainly into the 60-65
degree range.
Sunday night and Monday...
After another chilly night with more frost expected over parts of
northern and central WI Sunday night, more sunshine is forecast on
Monday as the surface ridge slowly slides to the east. On
difference will be winds where a southerly component is
anticipated. These winds, coupled with a stronger push of WAA,
will bring max temperatures on Monday into the lower to middle 60s
near Lake MI, middle to upper 60s inland.
Monday night through Thursday...
Dry and mild conditions look to persist through Tuesday, but
forecast confidence takes a big hit thereafter as models
significantly differ with the movement of a shortwave trough and
a surface cold front. The ECMWF is almost 30 hours faster than the
GFS/CMC models with respect to the shortwave trough. A slower
solution would keep Wednesday dry and mild whereas the faster
solution would bring chance pops and cooler conditions to the
area. Until this picture becomes more clear, will need to defer to
the consensus solution which brings small chance pops across
northeast WI for both Wednesday and Thursday. One aspect the
models seem to agree on is the return to normal or even slightly
below normal temperatures by next Thursday.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 955 PM CDT Thu Oct 14 2021
Generally good aviation weather conditions are anticipated tonight
and Friday. Relatively light surface winds are expected
overnight. Incoming high and middle clouds streaming across the
area should help prevent widespread fog formation, though patchy
MIFG is possible. Otherwise, anticipate mainly VFR conditions for
the next 24 hours.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kallas
AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Indianapolis IN
1137 PM EDT Thu Oct 14 2021
...Updated Aviation Discussion...
.Forecast Update...
Issued at 944 PM EDT Thu Oct 14 2021
Surface analysis late this evening shows a boundary stretched from
NW OH across Central Indiana to SRN IL. Water vapor imagery
continues to show a tropical plume of moisture stretching from
Louisiana and the Gulf of Mexico to points NE including the Ohio
Valley. Radar shows scattered showers with isolated thunder along
and near the stalled boundary...while more widespread rain was found
over Central Illinois...moving NE within the flow aloft. Dew point
temps were in the middle 60s.
HRRR shows much of the moisture over Central IL pushing NE and
crossing the NW parts of Central Indiana. Meanwhile the isolated
thunder in place near the boundary is expected to push northeast and
also diminish. Thus has trended pops highest across NW parts of
Indiana through about 300AM...while keeping chance pops elsewhere
where areal coverage is much less. kept any thunder mention to the
warmer air along and south of the stalled boundary. Given the clouds
and precip expected, will trend lows near dewpoints.
&&
.Short Term...(This evening through Friday night)
Issued at 312 PM EDT Thu Oct 14 2021
Radar trends and CAMS support occasional showers and embedded
thunderstorms over areas from around Winchester to Indianapolis to
Sullivan and north tapering off to chance PoPs far southeast.
Marginal Risk for severe thunderstorms late this afternoon and
early evening due to strong deep shear and weak to moderate
instability with surface based CAPEs currently maximized along the
Interstate 69 corridor at around 1000 J/KG. Front was moving into
northwest Indiana and will stall tonight somewhere near the
Interstate 70 corridor as surface waves move along the front and
waves eject northeast across the area ahead of a vigorous High
Plains trough. Precipitable water values maximized for this time of
year over 1.5 inches, the synoptic forcing and sufficient
instability will also support heavy rain at times with over an inch
possible at some locales. In fact, central Indiana is in a Marginal
Risk for flooding tonight per the Day 1 WPC Excessive Rainfall
Outlook.
All the ingredients for the potential for more moderate to heavy
rain and isolated severe thunderstorms on Friday as the cold front
slides southeast across central Indiana courtesy of an approaching
sharp upper trough and surface high pressure over the Rockies and
High Plains.
Low level 30 knot jet pointing in from western Kentucky will keep
precipitable water amounts near max for this time of year. This deep
moisture will combine with strong deep layer shear of over 50 knots
and low level shear near 50 knots to support the potential for a few
severe thunderstorms per the SPC DAY2 Severe Weather Outlook.
Although, damaging winds will be the main severe threat, would not
rule out a brief tornado or two late in the day if there are enough
breaks in the clouds to result in enough instability for prolonged
updrafts. Otherwise, the weak instability with mixed layer CAPEs
less than 1000 J/KG will be the main limiting factor to severe
weather. With the front moving through, best chances of severe
storms will be southeast of a Muncie to Indianapolis to Vincennes
line.
115 plus knot upper level jet streak lifting northeast around the
base of the trough over northeastern Illinois late in the day
supports moderate to heavy rain and the threat for minor localized
flooding per the day 2 WPC excessive rainfall outlook. 1 to near 2
inch storm total rainfall looks reasonable. Needless to say, 80 to
90 plus percent PoPs look good. The rain will move east into Ohio
overnight Friday night into Saturday morning. Look for storm total
rainfall of half an inch to over an inch over most or all locations.
&&
.Long Term...(Saturday through Thursday)
Issued at 312 PM EDT Thu Oct 14 2021
Much cooler weather is on the way following the passage of a strong
cold front Friday night. In the wake of this front, strong CAA will
build surface high pressure, co located with depressed heights and
cold air aloft. This will lead to sunny skies and below seasonal
temperatures Saturday, with highs in the upper 50s to low 60s across
central Indiana. Expect winds to be brisk on Saturday within the
strong CAA. Nearly clear skies and steep PBL lapse rates should
create mixing in the afternoon, pushing even stronger winds to the
surface with gusts up to 30mph.
In what will be a fairly progressive pattern along a strong Polar
Jet, these cool conditions will swing back towards seasonal rather
quickly. Ridging aloft will quickly move over the Ohio Valley early
next week, backed by a significant area of low level WAA east of a
broad low. This will push temperatures back into the low 70s, for
most of next week. With high pressure still providing broad
subsidence over the region for early next week, conditions are
expected to remain dry.
Forecast confidence lowers for the end of next week, as another wave
approaches from the west. For this reason, small chances for PoPs
have been introduced for Day 7.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1137 PM EDT Thu Oct 14 2021
IMPACTS:
- Flying conditions will deteriorate to MVFR and possibly worse IFR
predawn.
- Isolated lightning possible mainly near BMG.
- A return to MVFR on late morning and afternoon...but more rain
will be expected aft 152200Z.
DISCUSSION:
An area of showers associated will push across NW parts of the
forecast area impacting the LAF and HUF and IND taf sites early in
the TAf period. A weak boundary was stalled across the southern
parts of Central Indiana...but still north of BMG. As the rain as
seen on radar moves across the area...IFR cigs are expected to
develop near daybreak...but conditions should improve through the
morning hours as the forcing with the showers exits and daytime
heating resumes. Kept any thunder mention closer to BMG where
instability appears to be a bit stronger.
Another surge of moisture and forcing within the tropical flow aloft
is expected to arrive on Friday afternoon and Friday night. This
will bring a return to more MVFR Cigs and areas of rain.
Winds will be northwest at most of the TAF sites...with the exception
of BMG as that location will be ahead of the stalled frontal
boundary.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Puma
Short Term...MK
Long Term...Updike
Aviation...JP
Area Forecast Discussion
National Weather Service New Orleans LA
649 PM CDT Thu Oct 14 2021
.AVIATION (00Z TAF DISCUSSION)...Conditions look favorable for a
widespread fog and low stratus event to impact all of the
terminals between 08z and 15z. Light boundary layer flow of less
than 15 knots will support boundary layer decoupling. As the
boundary layer decouples and a deep inversion forms, high
relative humidity values will support fog development. LIFR and
VLIFR conditions are expected to occur for several hours at KASD,
KHDC, and KMCB. Visibilities may fall to near zero at times at
these terminals around 12z. By 15z, increased thermal mixing
within boundary layer will lead to improving conditions at all of
the terminals. VFR conditions should be in place by 18z. There
will be a risk of some scattered convection between 18z and 00z,
but the threat is too low to include in the forecast at this time.
PG
&&
.PREV DISCUSSION... /issued 402 PM CDT Thu Oct 14 2021/
SHORT TERM (This evening through Sunday Night)...
Partly cloudy skies and warm temperatures will end the day today,
similar to the past several days. Glancing at GOES-16 Ch.2 VIS
late this afternoon shows patchy cumulus ongoing, with radar
showing little, if any light shower activity which was anticipated
for today. Soundings illustrate what was discussed in the morning
update with southerly to southeasterly winds helping to increase
moisture, extending in depth aloft in the lower troposphere. This
helped pop up a few isolated showers today, and checking over
recent HRRR runs shows an isolated shower or two may still be
possible through the evening and overnight hours. Otherwise,
expect the cumulus field to dissipate as we decouple this evening,
with only some patchy upper-level cirrus advecting along
westerly flow in the 200-300mb layer, sheared off from convection
ongoing across coastal Texas.
The main focus for tonight will be areas of fog developing
generally in the same areas we saw earlier this morning, however
deterministic and blended probabilistic guidance is coming in a
bit stronger with the potential for dense fog formation. At this
time, likelihood for dense fog has been highlighted by a Dense
Fog Advisory which will go in effect at 5AM through 9AM, as we
very well could see a few hour window of dense fog issues. Without
getting too cute on specific areas, the focus will be from Baton
Rouge, generally along and also north of I-10/12 over the
northshore to coastal Mississippi. Less confidence for areas
further south - but will monitor for possible
expansions/cancellations per trends in observations.
Meanwhile overnight tonight, above the surface, deep-moist ascent
will continue to ascend/lift and dissipate the inversion that has
kept us mostly dry over the past several days. What this in turn
will do is lead to another day of pop-up showers, perhaps with a
bit more coverage thanks to the inversion eroding (enough) to
help parcels ascend in vertical depth, plus with a bit more
available moisture to work with, it will not take much to get some
showers going. However, with what is left of the inversion still
there, lifting a SB parcel only reveals a small slither of
available energy in the H7 to H5 layer and above. Showers, should
they grow tall enough will struggle to produce lightning - and
have kept any thunder wording out of the forecast for now.
Ofcourse, a stray rumble or two can not be ruled out, but too
small of a risk to mention in the forecast.
Focus shifts back to the west at a cold front, picking up pace
towards the east approaches our area. Taking a step back and
looking at the entire US reveals this to be quite the potent front
with deepening western US troughing quickly accelerating east
allowing for large-scale ridging to build out west, with plenty
of upper-level convergence to support a nice, big surface high to
slide in from the intermountain west. Downstream of the trough
axis (moreso an embedded shortwave) will be a weak surface low,
progressively deepening as it races northeast from the mid MS
valley region into the Ohio Valley region. Meanwhile for us, all
we are left with is a quasi-zonal west to east flow from the near-
surface and aloft as better dynamics and associated height falls
remains well to our north. No real modification is done in the
mid-levels to the left over inversion, which keeps us under an
overall "warm" thermal profile in the vertical revealing -5 to -6C
H5 temperatures and lapse rates in the 5 to 5.5C/km range. As we
heat up during the day tomorrow, we will still build enough
instability to support showers as mentioned before, but the only
real forcing available will be from the front itself. Meaning,
this will likely be a thin line that ignites Friday afternoon
along the front from coastal Texas, northeast across central LA
and north-central MS during peak afternoon heating. But that is
pretty much all that is fueling this line of showers and a few
storms, combined with the only forcing being along the front
because once this line enters the far NW portions of our CWA
around 8 to 10PM, it will steadily fall apart. One thing to
mention, CAM`s typically decay convection forced along a front too
quickly after sunset, meaning this line could progress enough
into our CWA for most folks to see rain (mainly areas along/west
of I-55), but east of I-55, there may not be much left of this
line, even going into parts of southeastern LA as well. Overall
with all said, not anticipating a washout or any severe weather,
but a quick burst of rain will be possible followed by a sharp
change in northerly winds and cooler temperatures to follow going
into Saturday morning.
Saturday is still promising to look very nice with cobalt blue
skies and cool temperatures. A breezy north wind will make it feel
very nice, but will be even more windy along north-facing
shorelines including the southshore and will be very windy along
nearby area lakes/sounds with offshore flow. As mentioned earlier,
the caveat in the forecast was the potential for some upper-level
clouds building in from a shortwave trough riding northeast
underneath large-scale ridging in the western US. The GFS has
backed off on the speed of clouds getting in here fast enough to
impact overnight lows Saturday night/Sunday morning. Seeing the
NBM starting to stairstep back down again placing many areas
along/north of I-10/12 into the upper 40`s, well below
deterministic blended guidance. The only thing to watch will be
if winds can calm enough to support maximized radiative cooling
processes, but am feeling comfortable in these values regardless,
maybe a bit cooler in typical cooler drainage areas along the
northshore and coastal MS. Sunday will be another gorgeous day yet
again and feeling cool, with winds not as breezy as Saturday
thanks to the surface high finally settling in. However, the same
trough mentioned before creeps into southern Texas, so does
supportive, downstream upper-level divergence and upper-level
cloud cover. We will see cirrus increasing through the day, but
still a nice day overall. By Sunday night/Monday morning, thicker
cloud cover builds in which even though winds finally relax enough
to support radiational cooling to take over, an increase in mid
and upper-level clouds could offset this effect leading to
temperatures several degrees warmer than what is forecast Sunday
morning. NBM is capturing this temperature trend nicely and should
not (hopefully) have to make too many more adjustments. Besides
all of this, a cool, dry and pleasant weekend awaits! Enjoy! KLG
LONG TERM (Monday through Thursday)...
The surface high pressure system will slide to the east on Monday
turning winds more easterly. A weaker upper level shortwave does
move through the area during the day, but this isn`t expected to
bring any moisture with it. This keep conditions dry and quiet for
Monday. As the surface high pressure system continues to move
eastward of our CWA wind will eventually turn southeasterly into
Tuesday and Wednesday which will help pull some moisture from the
Gulf back up over land. With the flow expected to be on the weaker
side most moisture looks to effect coastal and marine areas but we
may see some isolated inland areas with a shower or two. Thus
isolated to scattered PoPs are in the forecast for Tuesday and more
so into Wednesday, mainly along coastal areas.
After Wednesday we see a big deviance in the GFS and ECMWF, with the
former showing a good amount of moisture moving into our region with
a frontal passage associated with a low pressure system over the
Midwest. The ECMWF does not show the associated low pressure system
over the Midwest nearly as strong as the GFS, resulting in it
showing little to no moisture for our CWA. Given this big difference
in model data, expect changes in the PoPs for late next week.
High temperatures are expected to be cooler on Monday after the cold
front, with values in the mid 70s for most. Low temperatures
dropping all the way into the upper 40s to low 50s for some northern
areas overnight and the mid to upper 50s for areas closer to the
coast. Tuesday through Thursday high temps return to the low 80s and
low temps sit in the low to mid 60s for northern areas and the mid
to upper 60s along the coast.
-HL
AVIATION (18Z TAF DISCUSSION)...
Expect primarily VFR conditions this afternoon, with intermittent
MVFR due to periodic lower CIG`s from patchy low-level cumulus
through sunset. Few light showers between MSY, NEW and ASD, with
the mention of VCSH in these terminals, otherwise these showers
will not pose a significant impact other than temporarily reduced
VIS leading to a quick reduction in flight categories. Otherwise,
we dry out tonight with VFR prevailing after 00Z.
After 06 to 09Z tonight, widespread fog and low CIGs will likely
develop across the same areas as we saw this morning, perhaps a
bit more coverage east to ASD and HUM. Some areas, especially BTR,
HDC and MCB may likely see periods of dense surface fog, with
LIFR/IFR conditions for a few hours. Conditions will improve
around daybreak or shortly thereafter, revealing primarily
VFR/MVFR conditions into the morning hours. KLG
MARINE...
Persistent southeasterly onshore flow will continue through
Friday, before a cold front swings across coastal waters early
Saturday morning. Expect winds to increase from the north behind
the front, likely reaching Small Craft Advisory as waves/seas also
increase thereafter into the upcoming weekend. Generally
expecting around 2 to 4ft waves for protected waters, to 4 to 9ft
for outer 20-60nm zones at this time with the peak highest waves
during the day on Saturday through Saturday evening. Thereafter,
winds and waves/seas diminish steadily going into early to middle
parts of next week, with winds transitioning from the east and
staying light. KLG
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 71 88 58 72 / 10 30 30 0
BTR 71 88 59 73 / 20 40 20 0
ASD 70 89 62 77 / 0 30 40 0
MSY 73 89 67 76 / 0 30 40 0
GPT 71 87 65 77 / 0 20 50 10
PQL 69 87 64 78 / 0 10 40 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Dense Fog Advisory from 5 AM to 9 AM CDT Friday for LAZ036-037-
039-047-048-050-071-072-075.
GM...None.
MS...Dense Fog Advisory from 5 AM to 9 AM CDT Friday for MSZ069>071-
077-080>082.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
639 PM EDT Thu Oct 14 2021
.SHORT TERM...(This evening through Friday)
Issued at 353 PM EDT THU OCT 14 2021
Water vapor imagery and RAP analysis show a trof over the Rockies
with a well-defined shortwave lifting nne vcnty of the
Manitoba/Ontario border. Mid-level dry slot associated with this
feature overspread the fcst area late night/this morning, and it
remains over the area. Low-level moisture swinging around the system
is brushing the western fcst area, leading to sct-bkn stratocu
there. Right entrance of jet streak across the Upper Lakes led to
considerable high cloudiness across the area this morning. With that
jet streak shifting off to the ne now, skies have become sunny
across the central and eastern fcst area. Current temps range from
the mid 50s at KIWD to the mid 60s central and e. Sunny skies and
downslope warming under ssw/sw winds has pushed temps toward 70F
from around Marquette to Munising. So yet another aftn of above
normal temps over all but the far w.
Western trof will shift e tonight/Fri with axis approaching the
Mississippi Valley by Fri evening. 850mb temps currently range from
around 2C at KIWD to around 11C at KERY. By late Fri aftn, 850mb
temps will range from around 1C at KIWD to around 3C at KERY. So,
gradual cooling will continue, more notably into the eastern fcst
area. Expect min temps tonight from the mid 30s F interior w to
low/mid 40s e and near the Lakes. Highs on Fri will be back on track
with mid Oct normals, particularly across the w. Readings will range
from the lwr 50s F w to around 60F e and s central.
Abundant low-level moisture to the w across the eastern Dakotas/MN
will be advecting e and ne, though some will be mixing out for the
remainder of the aftn. The resulting stratocu will be confined to
the western fcst area tonight. On Fri, this moisture combined with
the cooling air at 850mb should result in a little more stratocu
development across the fcst area as daytime heating gets underway.
With 850mb temps dropping to around 0C tonight/Fri across western
Lake Superior and with sfc water temp around 14C, some lake effect
-shra should begin to develop later tonight. There is enough
westerly component to the wind to warrant a schc mention of -shra n
of KCMX late tonight thru at least Fri morning. Shortwave moving
thru the base of trof will spin up low pres that will track to the
Lower Great Lakes Fri evening. This wave will pass too far to the s
and e to bring pcpn to the fcst area. There will be some upper
diffluence associated with the streak on the front end of the trof.
This will support increased mid/high clouds Fri, especially across
the e half of the fcst area. Lower levels appear too dry for any
pcpn concerns.
.LONG TERM...(Friday through Wednesday)
Issued at 305 AM EDT THU OCT 14 2021
Overall not expecting widespread impactful weather over the next
week. The main story will be closer to normal temperatures for the
weekend along with lake effect showers. Thereafter it begins to warm
for early next week.
The pattern will be progressive through early next week with
ensemble mean 500mb height anomalies showing troughing/negative
height anomalies over the Great Lakes this weekend with
ridging/positive height anomalies building into northern and
central Canada early next week, keeping our area under a northwest
flow aloft. The result will be cooler, closer to normal
temperatures this weekend with another period of daytime
temperatures running around 10 degrees above seasonal averages
early next week.
As far as precipitation chances...as the upper level trough swings
in this weekend the main jet dynamics and forcing will remain south
and east of the area with a surface low pressure progged to
deepen as it lifts north into NW Ohio Friday and Ontario/Quebec
on Saturday. Locations in the eastern U.P could be on the western
fringe of the precipitation shield Friday but a better chance for
showers will come as the low levels cool enough for lake effect
rain showers to develop late Friday night into Saturday for the
west and northwest wind belts. While 850mb temperatures are not
impressively cool, they fall to around -2C on Saturday and given
lake surface temperatures running well above average, around 15C,
the delta-T of around 15 to 17C with inversion heights above 5kft
should be sufficient for at least moderate lake effect rain
showers. A surface ridge and drier air moves in for Sunday ending
the lake effect showers for most areas though the east could hold
onto at least a few showers into the afternoon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 639 PM EDT THU OCT 14 2021
There will be MVFR conditions overnight at IWD and CMX, otherwise it
will be VFR through the period. SAW will stay VFR through the whole
period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 353 PM EDT THU OCT 14 2021
With low pres lifting thru eastern Manitoba toward Hudson Bay
tonight, sw winds up the w half of Lake Superior will continue to
gust to around 30kt tonight, especially during the evening. Expect a
few gale force gusts to around 35kt at higher obs platforms as well.
Gusts to 20-25kt will be more common across eastern Lake Superior.
Winds veer slightly more westerly on Fri and then to the nw on Fri
night. Gusts to around 25kt will be common during this time. Over
the weekend, a seasonal air mass will be over the area, leading to
unstable conditions over the lake and more efficient mixing of winds
in the lower levels. Result will be nw winds gusting up to 30kt
Sat/Sun, especially on Sat when air mass will be cooler and the pres
gradient tighter due to low pres lifting across western Quebec.
There may be some gale force gusts to 35kt Sat/Sat night over
central and eastern Lake Superior. A high pres ridge will arrive Sun
night/Mon, bringing lighter winds under 20kt. Winds will increase
some on Tue as the ridge shifts e.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...NL
AVIATION...07
MARINE...Rolfson
...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 305 PM CDT Thu Oct 14 2021
Pretty quiet across the forecast area this afternoon aside from
increasing mid-level clouds. Temperatures at 3 PM ranged from the
mid 50s toward central Nebraska to the lower and mid 60s in
eastern Nebraska into southwest Iowa. The main forecast challenge
over the next 24 hours will be chances for light rain overnight.
Radar imagery has shown returns gradually strengthening/increasing
in coverage from central Nebraska into southwest Nebraska, likely
tied to some weak mid-level frontogenesis per SPC Mesoanalysis.
That said, ground truth observations have been rather spotty owing
to some dry air in the low levels. However, RAP guidance shows
the frontogenesis strengthens and deepens a bit as it progresses
eastward this evening and overnight. In addition, some shortwave
energy currently seen rounding the base of a larger scale trough
centered over the Rockies will provide some additional support for
shower development. The main question will be how much actually
reaches the ground due to the aforementioned dry air in the low
levels, but given the upstream observations and strengthening
forcing, should be enough to warrant at least some low precip
chances overnight.
The trough passes through the area on Friday leading to the
coldest day of the week as temperatures across the area are
expected to be in the mid 50s to right around 60 degrees. Surface
high pressure will also be building in and lead to decreasing
clouds, but will also bring somewhat breezy northwest winds. The
clear skies should lead to another cool night with lows in the 30s
for possibly the entire area along with widespread frost.
However, the surface high will be passing well to the south
leaving the forecast area under at least somewhat of a pressure
gradient, so winds could stay up and lead to slightly warmer
temperatures than we`d otherwise see (i.e. it`s looking unlikely
we see a hard freeze anywhere).
Upper level ridging will build in heading into the weekend and
early next week, leading to some dry and rather pleasant October
weather, with widespread highs in the 70s Sunday and Monday.
Heading further into next week, guidance is in good agreement of
the ridging quickly pushing eastward while another fairly potent
cutoff low approaches the area sometime Tuesday into Wednesday.
However, there remains significant model spread in timing and
track of the system, so confidence in exact precip timing remains
quite low, though it seems we`ll see at least some low end chances
at some point pending how much moisture is available. In
addition, we`ll likely be cooling back down toward the middle to
latter part of the work week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 625 PM CDT Thu Oct 14 2021
Still on track with lowering cigs, I`ve bumped our expected cigs a
bit lower based on upstream obs. A few light showers remain
possible at all three TAF sites... as reflected in "VCSH" mention.
Expect skies to mostly clear by noon tomorrow as wind speeds pick
up. Will see some Friday afternoon gusts of 20-25 knots.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...CA
AVIATION...Nicolaisen
Area Forecast Discussion
National Weather Service Norman OK
538 PM CDT Thu Oct 14 2021
...New AVIATION, UPPER AIR...
.SHORT TERM...
(This evening through Friday)
Issued at 222 PM CDT Thu Oct 14 2021
Currently, there is a surface low centered over Harper County
with a dryline extending southwest to near Erick, with another
weak surface low near Childress. The previous quasi-stationary
front has since lifted northward into southern Kansas.
Showers and thunderstorms will likely develop over west-central
Oklahoma late evening (around 04Z) as the cold front progresses
into northwest Oklahoma and as the low heads eastward from
Childress towards Vernon. With mostly elevated instability, large
hail up to the size of half dollars are the main threat. The 18Z
HRRR suggests weak surface instability on the order of 500 J/kg,
and marginal 0-1km shear of 15-20 kts. Therefore, confidence is
low on the tornado threat. Scattered storms will grow upscale into
a line along the front and progress across central Oklahoma
overnight (06-08Z). Locally heavy rainfall may also lead to flash
flooding, mainly across east-central Oklahoma.
Tomorrow, clouds are expected to diminish from west to east, with
gusty north winds and highs in the 60s for most areas.
Showers/storms are expected to exit by mid-morning.
Thompson
&&
.LONG TERM...
(Friday night through next Wednesday)
Issued at 324 PM CDT Thu Oct 14 2021
The mid-level trough axis and the cold front will be moving away
from the area by 00Z/16 and precipitation will be well east of the
area. And this is the beginning of a period of dry weather and
near or below normal temperatures for the next few days. Mid-level
ridging will move into and hang out over the area through the
weekend. The mid-level ridge will finally move to our east early
next week. A mid-level trough is expected to move from western
Oklahoma into the central/northern Plains, and the main forcing
with this currently looks to remain northwest of the area,
although there is some potential for shortwaves to move in from
the west or southwest that may give at least low precipitation
potential early/mid week.
&&
.AVIATION...
(00Z TAFS)
Issued at 532 PM CDT Thu Oct 14 2021
Some residual MVFR ceilings across north central Oklahoma may
linger through the evening. Othewise, expect to see redevelopment
of MVFR ceilings most other locations this evening outside of
CSM/WWR. To go along with this, storms development is anticipated
around 02-03Z across western Oklahoma, which will then translate
east and northeast ahead of a cold front. Storms expected to
impact OKC/OUN/SWO/PNC. This activity will move by with slow
clearing of lower clouds Friday morning. Behind the front south
winds will shift to the north and then increase mainly after
sunrise into the mid-morning hours. Gusts of 25 to over 30kts
likely.
&&
.UPPER AIR...
Issued at 532 PM CDT Thu Oct 14 2021
An Upper Air flight is planned for 00Z this evening.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 54 62 42 68 / 70 10 0 0
Hobart OK 50 67 39 72 / 70 0 0 0
Wichita Falls TX 55 68 42 71 / 10 0 0 0
Gage OK 44 63 36 71 / 10 0 0 0
Ponca City OK 51 63 38 68 / 50 20 0 0
Durant OK 63 70 45 71 / 30 20 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
SHORT TERM...01
LONG TERM....26
AVIATION...30