Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/23/19
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1035 PM EDT Sun Sep 22 2019
.SYNOPSIS...
A southwest return flow around high pressure off the Mid
Atlantic Coast, will bring mild conditions tonight into Monday.
A cold front will cross the area late Monday, bringing showers
and isolated to scattered thunderstorms Monday afternoon into
the early evening. A cooler air mass will be over the region on
Tuesday with isolated to scattered showers possible. Fair and
dry weather returns for Wednesday as high pressure builds in
from the Ohio Valley.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 1035 PM EDT...High clouds have increased a little bit,
as they move over the area from the west. Temperatures in a
couple of spots have fallen lower than previously forecast, but
most of going forecast was on track. Mainly fair and mild night
continues.
Previous...
The majority of the high resolution mesoscale guidance has
trended drier for the mid to late pm across the west northwest
portion of the forecast area. We did keep an isolated threat for
a shower as a lake breeze or differential heating boundary may
focus a few over the southern Adirondacks, west-central Mohawk
Valley and the northern Catskills between 21Z-00Z. The 3-km NAM
and ARW-WRF2 support this...but the 3-km HRRR and traditional
ARW-WRF indicate dry conditions. Any activity should shrivel up
with the loss of the diurnal heating.
Tonight...A balmy night will be on tap compared to the last
several with high pressure off the mid Atlantic coast continuing
to pump mild air into the region. Lows will be in the mid and
upper 60s in the lower elevations with upper 50s to lower/mid
60s over the higher terrain. Some low stratus may form and creep
into western New England and the mid Hudson Valley. South to
southwest winds will be 5 to 15 mph.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Tomorrow...The mid and upper level ridge breaks down as the flow
aloft strengthens from the southwest. A potent mid and upper
level low will be approaching from the Great Lakes Region and
Ontario. A muggy air mass will continue ahead of the approaching
short-wave trough and a sfc cold front. Scattered showers will
likely blossom in the afternoon ahead of the front, as mid and
upper level heights fall. Some isolated to scattered
thunderstorms are possible, but again instability in any shape,
variety or computed form looks fairly weak with 750 J/kg or
less with the sfc dewpts in the 60s. Their could be a few gusts
of wind in the 35-50 mph range with any taller updrafts
achieved. The deep shear and dynamics aloft are good with upper
level divergence and the forecast area near the left front
quadrant of a mid an upper level jet streak by 00Z/TUE. The
severe threat is not zero, but the probability is very low. The
greatest chance for thunderstorms looks like 4 pm to 10 pm.
Highs will be above normal with 70s to lower to mid 80s across
the region. PWATS will surge +1 to +3 STDEVs above normal based
on the 12Z GEFS, but with flow so fast aloft, and bone dry
conditions lately (no rain in a week), any bursts of rain will
be quick. A tenth to a third of an inch of rain will be
welcomed.
Mon Night...Cooler air will invade the region for the 1st day of
Autumn (it will have begun at 350 am EDT on Mon). Some isolated
to scattered showers will linger into the early evening with the
upper low moving overhead. Lows will fall back into the 50s to
around 60F across the region.
Tuesday...Clearing is expected south of the I-90 corridor, but
the cyclonic vorticity advection with the closed upper low
coupled with minimal heating will allow for terrain forced and
instability showers forming over the northern zones. Any
additional QPF will be light. H850 temps will be a shade below
normal, but nothing way below normal for the opening days of
Fall. It will be brisk and cool compared to the previous few
days with highs in the mid 60s to lower 70s in the valleys, and
50s to mid 60s over the higher terrain.
Tuesday night to Wednesday...High pressure builds in with fair
and dry weather returning. A cool night with temps in the 40s
to around 50F will be followed by a nice start to the mid week
with highs near normal in the 60s to lower 70s for most of the
region.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The period starts out Wednesday night with a progressive cold front
and associated low-amplitude upper level trough approaching from the
Great Lakes region. Guidance in good agreement with timing, as a few
showers may make it into the the northwest part of our area by
sunrise Thursday. Much of the area will remain dry through the night.
The front and upper trough will move across our region on Thursday.
Once again moisture looks to be limited, although low level
convergence along the front and some forcing from the upper trough
should result in at least scattered showers for much of the area.
Temperatures will continue to be mild ahead of the cold front,
cooling off in the Adirondacks where the front will be likely moving
through earlier in the day.
A period of dry and increasingly warmer weather then looks to occur
during the Friday through Sunday time frame, as yet another upper
level ridge is expected to build along the east coast. Initially,
temperatures will be slightly above normal Friday, but then well
above normal levels will be possible over the weekend as the ridge
strengthens. There are some model differences, with the GFS
indicating a cold front passage Saturday night. However, will side
more with the drier/warmer ECMWF and CMC, which have the strong
upper ridge remaining in place.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Low Level Wind Shear expected at all TAF sites from this evening
through the overnight period and included in TAFs.
Mainly VFR conditions are expected through 18Z Monday as high
pressure holds its influence on the region. Mainly high clouds
expected overnight and Monday morning. Some MVFR/IFR fog
expected at KGFL as winds have gone calm already. With light
winds overnight, do not expect any fog to form at other TAF
sites. Precipitation chances increase beyond 18Z/Monday with the
cold front.
Winds will remain south to southwest between 5 and 10 kts
overnight except KGFL where they will be calm most of the night.
After daybreak Monday, south to southwest winds will increase
to around 10 kts with gusts up to 20kts.
Outlook...
Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: Low Operational Impact. Slight Chance of SHRA.
Tuesday Night to Friday: No Operational Impact. NO SIG WX.
&&
.FIRE WEATHER...
High pressure off the Mid Atlantic Coast will bring mild
conditions to the region tonight. A cold front and a strong upper
level disturbance will bring showers and isolated to scattered
thunderstorms tomorrow afternoon into the early evening. Cooler
conditions return on Tuesday, as an upper low will keep isolated
to scattered shower going for locations north of the Capital
Region.
The RH values will increase to 75 to 100 percent Monday morning,
and the drop to 45 to 75 percent by the afternoon. The maximum
RH values Tuesday morning will be in the 85 to 100 percent
range.
The winds will be south to southwest at 5 to 10 mph tonight,
then increase to 10 to 20 mph during the afternoon before
veering to the west to northwest at 10 to 20 mph by the late
afternoon into the early evening.
A widespread wetting, but light rain may occur across the
region tomorrow into Tuesday with amounts range from a tenth to
third of an inch or so. It has not rained in about a week.
&&
.HYDROLOGY...
No hydrologic problems are anticipated across the region over
the next 7 days.
The next chance of rain will be ahead of a frontal boundary and
an upper level disturbance on Monday into Tuesday morning. Most
spots will see between one tenth and one third of an inch of
rain, which will have little impact on area rivers and
streams...maybe flows will rise a few centimeters and then
recede.
According to USGS streamflow, most area rivers are
seeing near normal or below normal flows for mid to late
September.
Lingering showers on Tuesday (especially for northern areas)may
yield additional rainfall amounts of a few hundredths to a
tenth of an inch.
More dry weather is expected for Tuesday night into the mid
week.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...SND/Wasula
NEAR TERM...SND/Wasula
SHORT TERM...Wasula
LONG TERM...JPV
AVIATION...SND
FIRE WEATHER...Wasula
HYDROLOGY...Frugis/Wasula
Area Forecast Discussion
National Weather Service Caribou ME
1122 PM EDT Sun Sep 22 2019
.SYNOPSIS...
High pressure will continue to move south of the region overnight.
Low pressure will approach Monday and slowly cross northern
Maine through Wednesday morning. High pressure will build over
the area Wednesday evening. A cold front will approach and cross
the area on Thursday followed by high pressure on Friday.
&&
.NEAR TERM /THROUGH MONDAY/...
1120 PM Update...Adjusted the pops and temps to reflect the
latest conditions. Radar showed isolated showers moving toward
NW ME. Pulled back on the timing some using the HRRR and High
Res WRF. Should see showers showing up across northern areas by
early Monday morning. Temps were holding steady in the upper
60s to lower 70s. Tweaks were made to show temps dropping off
slightly overnight. Rest of the forecast looks fine.
Previous Forecast...
A southwest flow will be in place across the region tonight
between an approaching cold front from the northwest and high
pressure off the mid-atlantic. The southwest breeze and
increasing cloud cover will keep low temperatures generally in
the low to mid 60s across the region. A few showers are expected
to develop across far northern areas overnight, especially
toward the St.John Valley nearer to the approaching cold front.
The cold front will slowly move south across Northern areas on
Monday. Expect mainly cloudy skies and a chance for showers
across northern and central areas on Monday. Across central and
downeast areas, expect a partly sunny start followed by
increasing afternoon clouds along with scattered showers and
perhaps an isolated afternoon thunderstorm. Highs on Monday
across the north will still be above normal but not as warm as
today, with generally low to mid 70s expected. Across central
and downeast areas, highs will be near 80 degrees but a little
cooler near the coast.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
By Mon ngt, an upper low crossing E across QB prov will be close
enough to result in weak secondary sfc cyclogenesis ovr Downeast,
with banding of shwrs movg W to E into our FA, and then SW to
NE across our FA on Tue. Depending on where the banding with
isolated thunder occurs (which looks msly Cntrl and Downeast
attm) and longevity ovr ptns of the FA, there is the potential
of sig to lcly hvy rnfl late Mon ngt thru Tue eve, but for now,
given the uncertainty of these factors, we went middle of the
road for fcst 6 hrly QPF values for our Rgn thru this tm frame
with max 90+ percent PoPs. Lgtr rnfl will cont late Tue ngt
with shwrs becoming sct Wed morn as both sfc and upper low move
E across the Can Maritimes, then ending Wed aftn. Temps will be
cooler both Tue and Wed, spcly N and Cntrl areas with mild
ovrngt lows.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Our FA will receive a brief respite between system Wed eve into
ovrngt before cldnss increases ahead of the next s/wv trof apchg
from Cntrl Can late Wed ngt. Shwrs will then move into the FA by
Thu ahead of the cold front associated with the s/wv as the s/wv
moves msly N of our Rgn. Subsequently, the best event rnfl
potential of a quarter to half inch will likely be experienced
across the N where we weight the highest PoPs in the likely
range with both lower PoPs and QPF Cntrl and Downeast areas.
Shwrs end behind the cold front late Thu ngt, resulting in the
return of fair, breezy and dry erly fall like wx for Fri and Sat
as sfc hi pres from the great lks builds toward and crests the
Rgn with the slower 12z ECMWF favored ovr the faster 00z GFS
model solution for dry conditions Sat.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
NEAR TERM: VFR conditions expected tonight with southwest winds
around 10 kts. Low level wind shear is possible vicinity
KHUL/KBGR late tonight through early Monday morning. MVFR
conditions can be expected at the northern terminals on Monday
in showers with an approaching cold front. At KBGR/KBHB, VFR
conditions much of the day. Scattered showers and an isolated
thunderstorms are possible later Monday afternoon.
SHORT TO LONG TERM: Mon ngt thru Tue Ngt - IFR clgs/vsbys all
TAF sites mainly in shwrs/rn with patchy late ngt fog Downeast
sites late Mon ngt/early Tue morn. Lgt winds.
Wed - MVFR clgs all TAF sites improving to VFR Wed aftn. Lgt
winds.
Wed ngt - All sites VFR. Lgt winds.
Thu thru Thu ngt - All sites MVFR clgs/vsbys in shwrs. Lgt
Winds.
Fri - All sites VFR. Breezy NW winds.
&&
.MARINE...
NEAR TERM: A Small Craft Advisory is being issued beginning
around daybreak Monday and continuing through Monday afternoon
for the outer waters. Winds/seas are expected to slowly increase
overnight. On Monday expectd gusts to around 25 KT and seas 4 to
7 feet.
SHORT TO LONG TERM: Initially SCA conditions outer MZs mainly
for seas Mon ngt, subsiding below SCA by Tue morn, then cont`d
no hdlns for the remainder of the fcst. Went with about 90
percent blend of WW3/NWPS wv ht guidance for fcst wv hts,
compromised of two spectral wv pd groups; a short fetch 6 to 8
sec group and an open Atlc long pd swell group of 12 sec.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory from 8 AM Monday to 5 AM EDT Tuesday for
ANZ050-051.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Green Bay WI
642 PM CDT Sun Sep 22 2019
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Monday
Issued at 257 PM CDT Sun Sep 22 2019
The latest RAP analysis and satellite/radar imagery show a cold
front slowly moving east over eastern WI early this morning.
Widespread light rain continues over the Fox Valley and Lakeshore
areas ahead of the front, but lightning has been absent for the
past several hours across the region and also upstream.
Meanwhile, a shortwave is intensifying over the central Plains
with another area of rain moving northeast over Iowa and southern
Minnesota. Forecast concerns mainly revolve around rain trends
along the front, and rain potential tonight ahead of the
shortwave.
Tonight...Light to moderate rain should be exiting the lakeshore
areas late this afternoon or early this evening, resulting in a
break in the precip for a time. Then the shortwave over the Plains
will be swinging into the region during the evening. High res
models are becoming more ambitious with precip returning this
evening, thanks to moderate mid-level fgen and moisture
convergence arriving just ahead of the shortwave. Mid-level lapse
rates and instability are unimpressive tonight, but will keep a
slight chance of a thunderstorm given the strength of the
shortwave moving through. Some rain my linger though the night
over far northern WI though most rain should exit elsewhere
through the overnight.
Monday...Comma head moisture behind the shortwave will be pivoting
across northeast WI during the morning. Otherwise, steep low level
lapse rates will develop with the heat of the day. Combined with
low convective temps should result in scattered to broken cu
formation by late morning. The cu rule is also on board with this
scenario. Highs ranging from the mid 60s to low 70s.
.LONG TERM...Monday Night Through Sunday
Issued at 257 PM CDT Sun Sep 22 2019
A brief dry period with above normal temperatures will be had
Monday night and Tuesday before a low pressure system approaches
the region from the west. A cold front will then sweep through the
area late Tuesday night into Wednesday. The front will have
instability and shear to work with, especially out west, where
MLCAPEs will be 1000 to 1500 J/kg with around 40 knots of bulk
shear. Further east these values fall precipitously. There is a
chance some of the storms could be strong to severe, especially
out west given the instability and shear values, however the
timing of the front, later into the evening hours on Tuesday, will
not be that favorable for widespread severe weather development
over our area. If the timing of the front changes though this
could change.
High pressure will bring another brief break in precipitation
Wednesday night and Thursday along with cooler temperatures. Yet
another low pressure system will bring the chance for rain back to
the area late in the work week. Next weekend is a bit murky as
there are indications another low pressure system could bring
additional rain showers to the region by next Sunday.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 642 PM CDT Sun Sep 22 2019
An upper level disturbance will bring showers and MVFR conditions
as it moves across the area overnight. Ceilings and visibilities
will improve to VFR by midday Monday as drier air arrives.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kurimski
AVIATION.......RDM
Area Forecast Discussion
National Weather Service Grand Rapids MI
918 PM EDT Sun Sep 22 2019
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 315 PM EDT Sun Sep 22 2019
- Localized heavy rainfall possible through this evening
- Rain chances focused on Wednesday and Saturday
- Average to above average temperatures much of the week
&&
.UPDATE...
Issued at 915 PM EDT Sun Sep 22 2019
Radar shows one last decent area of rain moving across the west
central cwa. That will take a few hours to exit the cwa to the
east. Behind that, a few showers are moving northeast over
Wisconins. However, latest HRRR shows that more or less
diminishing before it moves over the cwa.
Not planning on any changes to the forecast tonight and all lake
shore headlines will remain in effect.
&&
.DISCUSSION...(This evening through next Sunday)
Issued at 315 PM EDT Sun Sep 22 2019
Our latest thoughts with this rain event are that most locations
should not see impactful rain amounts. We are thinking that there
will likely be a narrow axis of heavier rainfall that might create
some short term minor flooding of poor drainage and low lying areas.
Latest regional radar imagery is not impressive, and a lack of
upstream flooding reports corroborates this thinking. The rain over
Nrn Illinois and Ern Iowa is associated with a well defined wave
centered over Wrn Illinois. This is the rain that is expected to
move over most of the area through this evening. It will be a good
general soaking for the area. The hi-res models have been indicating
a narrow heavier rainfall axis, likely associated with the
deformation zone of the wave, that will likely move between I-96 and
I-94 this evening. It is in this area that the best potential for
some localized flooding. The threat should then end by 06z.
Thunder remains possible this evening, however the lack of upstream
lightning with this wave so far makes us believe that coverage will
be scattered at best. There could be a little uptick in lightning
with the system strengthening, and low level jet increasing. With
little lightning to start, the severe threat is quite low. A few
more showers will be possible with the cold front before daybreak.
Clouds will then clear out Monday afternoon.
We will see a break from Monday afternoon through Tuesday evening as
high pressure aloft and at the surface moves through. The next
chance of showers and a few storms will arrive early Wednesday
morning, and linger through Wednesday evening. This does not look to
concerning as it is fairly progressive, and instability is limited.
If we are able to destabilize a bit more Wed afternoon ahead of the
front, the storm threat may end up a little higher.
Again, we will see a brief break in the unsettled weather for
Thursday before the next chance for rain starts to move in on
Friday. There is good agreement with the front coming in. However,
there is a good deal of uncertainty on how quick it moves through.
This is actually defendant on the evolution of a western low/trough.
One possibility is that deep SW flow becomes established, and the
front may linger longer, and we stay wet for next weekend. Another
possibility is the upper low closes off over the desert SW, and the
system would be more progressive and move out quicker. We will fine
tune this as better trends become more clear.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 747 PM EDT Sun Sep 22 2019
A cold front stretches from Green Bay southwest to NE Missouri.
Showers are falling ahead of it and will temporarily reduce vsbys
as they move over the TAF sites this evening. After midnight, some
MVFR fog is possible and IFR fog is not out of the question. Fog
will dissipate by morning as drier air moves in and sfc winds
increase.
&&
.MARINE...
Issued at 315 PM EDT Sun Sep 22 2019
It looks like the Small Craft Advisory is working out nicely, and
should hold well through this system. We are currently seeing 25 to
30 knots fairly common along the lakeshore from the SW. Winds will
die off a bit as the system approaches, then will increase in the
wake of the front as the cold air rushes in. The winds will then
diminish Monday night.
Our next marine event will come beginning Tuesday night and through
Wednesday with the next fairly decent frontal system that will move
through. Small Craft Advisories will be likely once again.
&&
.HYDROLOGY...
Issued at 315 PM EDT Sun Sep 21 2019
Rainfall has already begun to move through lower MI this morning and
early afternoon resulting in up to 0.25-1" of rain with the higher
totals near and north of I-96. Meanwhile additional rainfall is
expected later on this afternoon and evening, leading to rainfall
totals up to 1-2 inches, locally up to 3 inches, by Monday morning.
This rainfall is expected to cause some rises on rivers, but no
rivers are expected to exceed bankfull. The rivers that may approach
bankfull are most likely the White and Pere Marquette rivers, where
heavy rain from last week has limited how much water the soil is
able to absorb.
Of greater concern is the potential for localized short-duration
flooding of some small streams as well as ponding on roadways at low-
spots and in poor drainage areas. The heaviest rain is likely to
fall in the communities northwest of a line from South Haven to
Saginaw. The heaviest rain looks like it will fall this evening and
overnight, and will be moving out of the area by Monday morning.
Water on roads at night is much harder to see, so drivers should
slow down and pay extra attention.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Monday evening for MIZ037-043-
050-056-064-071.
Lakeshore Flood Advisory until 8 PM EDT Monday for MIZ037-043-
050-056-064-071.
LM...Small Craft Advisory until 8 PM EDT Monday for LMZ844>849.
&&
$$
UPDATE...04
SYNOPSIS...NJJ
DISCUSSION...NJJ
AVIATION...04
HYDROLOGY...ANH
MARINE...NJJ
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
907 PM CDT Sun Sep 22 2019
.UPDATE...
907 PM CDT
The remaining portion of the Flash Flood Watch, which was set to
expire at 10 pm CDT, has been canceled. The initial cold front is
currently moving across the Chicago metro, and with it is
shifting the axis of higher PWAT air to the east of the CWA. The
mid-level trough axis, evident on WV satellite across eastern Iowa
at 9 pm, will likely bring isolated to scattered light to briefly
moderate rain showers across the area late this evening into the
overnight hours. While dew points and temps have lowered slightly
with the initial surface front, noticeably cooler and drier air
will arrive with a secondary front generally along or just ahead
of the final batch of showers.
Kluber
&&
.SHORT TERM...
330 PM CDT
Through Monday night...
The flash flood risk continues to sharply drop over the area due
to a limited duration of heavier rain. A quicker moving back
edge is the primary reason for this, but also less of an overall
footprint of the heaviest rain coverage. Have thus moved up the
end time of the Flash Flood Watch. Will still be watching for an
isolated flash flooding concern, as well as any brief gustier
showers mainly along and east of I-55.
The MCV embedded within the stronger southwest, moist flow is
entering the southwest forecast area and will continue across
Chicago through 7-8 p.m. This has been less pronounced with its
heavy rain shield than earlier in Missouri, possibly owing to some
moisture transport robbing from activity in southern Missouri.
There are still pockets of heavier rates, but they are small in
coverage and quick moving, with no observations the past 1-2 hours
of sites over one half inch in one hour. Thus the flash flood
risk seems really limited and the evening shift will likely be
able to peel away more of the watch at a quicker rate.
The southeast CWA had destabilized earlier based on modified RAP
soundings, and despite gradually falling temperatures now, there
likely still is some lower rooted CAPE. That should be preserved
these next few hours due to dew points inching up and an LFC just
off the deck. With slightly backed flow in central Illinois,
partly induced by the MCV, there continues the low possibility of
a threat of a brief tornado or two in the region (mainly south)
given the low-level speed and directional shear. Cells have not
shown any behavior as if they are harvesting that thus far.
Confidence on this remains very low and likely would only be the
eastern/southeastern part of the CWA in the outside chance it
materializes.
As this main MCV moves away, the area will still remain under
broad upper jet forcing for ascent and within the presence of
deep moisture for a few hours, but a period of mid-level
suppression and lack of focus should keep any showers more
scattered mid-evening through early overnight. A cold front will
be moving southeastward during that time turning winds
northwesterly and gradually ushering in drier air. Wind gusts will
be enough over the lake to result in a sufficient onshore
component for a heightened rip current risk in northwest Indiana
late tonight into Monday. The sky looks sunny on Monday with highs
in the 70s.
MTF
&&
.LONG TERM...
340 PM CDT
Monday Night through Sunday...
No major changes made to this period on the day shift.
Strong subsidence will continue to overspread the region Monday
night and into Tuesday as shortwave ridging (temporarily) builds
in overhead. Still think that the potential for fog development
looks fairly low even though moisture does look to remain trapped
in the lowest 5 kft under the developing inversion. A dense plume
of cirrus combined with soundings that show a propensity for
things to remain pretty well mixed immediately off the surface
should greatly curtail the potential for dense fog.
Surface high pressure will slide off to our south and east through
the day on Tuesday, allowing southerly return flow to develop back
across the region. Moisture looks to remain insufficient to
support precipitation chances until later Tuesday night into
Wednesday as the next robust shortwave trough pivots across the
Upper Midwest (but even then, moisture quality doesn`t look all
that impressive). A substantial 130 kt jet streak is expected to
nose into parts of Minnesota and southern Wisconsin during this
time, which will drive a notable low-level ageostrophic response
and ramp up a 50-55 kt low-level jet. While the dynamics with
this system will be robust, it looks to come in essentially at the
diurnal instability minimum. Forecast soundings look pretty
capped to surface-based convection, and it may even be difficult
to force elevated convection given a minimal amount of time for
more appreciable moisture return. The blended guidance chance pops
look reasonable at this point an no notable changes were made.
Could get a bit gusty late Wednesday morning and into the
afternoon as we tap into a belt of faster flow immediately off the
surface.
There is the chance for some post-frontal mid-level forcing on
Wednesday that could result in mainly just showers for most of the
area. Confidence on this is fairly low, but blended PoPs from
guidance did provide rain chances.
Looks like we`ll get another brief break on Thursday before the
next storm system brings a renewed potential for showers and
thunderstorms to the region to close out the week and into the
upcoming weekend. Certainly looks mild for Friday into the weekend
and according to the GFS and EC into the first days of October.
Carlaw/MTF
&&
.AVIATION...
For the 00Z TAFs...
632 PM...The back edge of the rain continues to slowly move east
across north central IL early this evening with a band of heavy
rain from arr/dpa/pwk that will affect ord over the next hour or
so. Vis under 1sm and ifr cigs are likely with this band of rain.
This should all shift east of the Chicago terminals by mid evening
with just isolated showers possible through the early overnight
hours. Coverage with these showers looks fairly low so just
vicinity mention for now.
Outside of heavy rain/possible ifr cigs...prevailing mvfr cigs in
the 1-2kft range look on track through early morning...clearing
from west to east.
Southerly winds have diminished with speeds under 10kts. Still
some gust potential with the heavier showers. Winds will then
shift more southwest or west as a trough moves across the area
this evening. Winds will shift to the northwest early in the
morning as a cold front moves across the area. Winds will remain
northwest Monday with some gusts to 20kts possible through sunset
Monday evening. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...Beach Hazards Statement...INZ002...3 AM Monday to 4 PM Monday.
LM...Small Craft Advisory...IL nearshore waters until 10 PM Sunday.
Small Craft Advisory...IN nearshore waters until 4 PM Monday.
&&
$$
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Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
623 PM CDT Sun Sep 22 2019
.UPDATE...
Issued at 608 PM CDT Sun Sep 22 2019
Updated to include 00z aviation discussion below.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 305 PM CDT Sun Sep 22 2019
Short term concern is extent of light showers moving across
the southeast CWA into the evening.
Latest radar showing some light showers beginning to pivot
northward across south central MN along the MN River Valley.
Water vapor imagery showing upper trough beginning to move into
western MN with vorticity extension/PIVA moving into southwest MN
at this time. Moisture was scoured some with early showers exiting
to the east, but there may be enough forcing to continue to lift
the showers across at least a portion of east central MN late
afternoon/early evening. The latest HRRR has begun to trend that
way. As the upper low continues to move east overnight, expect
clouds to thin some from the west and showers to end into west
central WI shortly after 06z Mon.
Monday looks to be mainly sunny with temperatures moderating again
with 70s common once again. Some high clouds may stream in later
Monday night from the west, but dry conditions should continue.
Lows Monday night should range in the low to mid 50s.
.LONG TERM...(Tuesday through Sunday)
Issued at 305 PM CDT Sun Sep 22 2019
The weather pattern will remain fairly active through at least
next week. Several storm systems will bring rain and
thunderstorms. In particular, there is a chance for severe storms
late Tuesday afternoon into Tuesday evening.
On Tuesday morning a very strong upper level will cross the
northern Rockies and race towards the upper Midwest. This will
drive a cold front through the region Tuesday afternoon. Surface
temperatures should warm into the lower 80s ahead of this cold
front, and dewpoints will climb into the mid 60s. 500mb height
falls together with low level convergence along the aforementioned
cold front should lead to convection by the late afternoon across
western Minnesota. These storms will quickly move eastward across
the rest of the region Tuesday evening. Damaging wind will
probably be the main threat with these storms since they will be
fast moving, and there will be large scale synoptic forcing for
ascent. The Storm Prediction Center currently has a slight risk
across much of the forecast area.
The cold front will push well south of the region on Wednesday,
and cold air advection will keep the boundary layer mixed and
wind gusts near 30 mph Wednesday afternoon. Increased the forecast
wind speeds to better align with the forecast soundings.
Surface high pressure will build in Wednesday night, but another
system will follow quickly on its heels and bring return flow and
moisture up from the south on Thursday into Friday. This will set
the stage for another round of thunderstorms with heavy rain as
the primary threat. Looking ahead, the pattern repeats itself
again Saturday and Sunday, and this could continue into early
October.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 608 PM CDT Sun Sep 22 2019
Improving conditions will be the story of these TAFs. Only site
with any lingering -SHRA at initialization will be KEAU while all
other TAF sites will be dry. The precip will be out of the KEAU
area by about 03z and will join the remaining TAF sites with
clearing skies thru the overnight hours with little if any high
clouds tomorrow. W winds 5-10 kts will back to SW by tomorrow and
remain in the 5-10 kt range.
KMSP...No significant weather impacts expected.
/OUTLOOK FOR KMSP/
Tue...Mainly VFR. Chance evening MVFR/TSRA. Wind SW 5-10 kts.
Wed...VFR. Wind NW 10-20 kts. Gusts 25-30 kts.
Thu...Mainly VFR. Chance evening MVFR/SHRA. Wind S 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
UPDATE...JPC
SHORT TERM...DWE
LONG TERM...JRB
AVIATION...JPC
Area Forecast Discussion
National Weather Service Nashville TN
905 PM CDT Sun Sep 22 2019
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Skies remain mostly clear this hour, despite a cold front
approaching Middle Tennessee from the northwest. The 00Z sounding
from OHX shows a dry, stable atmosphere still in place, which
doesn`t portend well for our rain chances later on. Expect clouds
to start increasing during the next few hours, and the latest
HRRR does show a few light echoes sneaking into the Land-between-
the-Lakes region prior to 12Z. So we`ll keep the low chance POP`s
for late tonight. The actual frontal boundary will begin edging
into Middle Tennessee shortly after 12Z. The current forecast
seems to be in good shape for now, so no changes are planned at
this time.
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR conditions overnight will give way to chances for showers and
maybe even a thunderstorm during the day tomorrow. Cigs/vis may
become MVFR or less should any heavy showers impact terminals.
Have in best timing with current CAM consensus for each terminal,
starting as early as 14Z for KCKV and as late as 19Z for KCSV.
Rain chances should diminish from northwest to southeast during
the late morning through the afternoon. Winds will be
southwesterly overnight into mid morning, then becoming more
westerly around 5 to 10 knots late morning/early afternoon, and
northwesterly around 5 to 10 knots by the end of the TAF period.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......08
AVIATION........Barnwell