Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/20/17
Area Forecast Discussion
National Weather Service Gaylord MI
1148 PM EDT Sun Mar 19 2017
.UPDATE...
Issued at 1003 PM EDT Sun Mar 19 2017
A bit of interesting weather out there this evening, as subtle
shortwave works in tandem with corridor of robust mid level lapse
rates and just enough elevated moisture to kick off a band of
showers and a few thunderstorms across the northern Lakes. This area
of showers is steadily moving east, and starting to get some hints
of intensification over Lake Michigan as it merges with low level
jet riding atop the lakes cold dome. However, nothing significant
for sure as low level dry air has really done a number on
precipitation amounts reaching the surface. Expect this trend to
continue for a few more hours, although loss of lake induced jet and
a relaxation of mid level lapse rates should gradually end the
thunder threat and cause a much more scattered appearance to shower
activity through the night. Have had some upstream reports of mixed
precipitation with initial surge of evaporational cooling, although
this has been very brief in nature. Expect the same for our area,
with perhaps the precip starting off as snow or even a touch of
light freezing rain, especially across eastern upper Michigan. Once
again, not expecting any significant impacts given light amounts and
short duration of wintry mix. Of course, would still use some
caution when traveling those secondary and untreated road surfaces.
&&
.NEAR TERM...(Tonight through Monday)
Issued at 337 PM EDT Sun Mar 19 2017
...Mild with light showers possible tonight into Monday...
High Impact Weather Potential...Minimal. Could be a few rumbles of
thunder along Lake Michigan overnight.
Pattern Synopsis/Forecast...Positively tilted upper level ridge axis
will continue to slide across Michigan heading into this evening. At
the surface, a sprawling high sitting over the area will push east
of Michigan by this evening. This has led to mostly sunny skies
across the much of the forecast area today, though mid/upper level
clouds are starting to increase. Temperature advection pattern has
been holding neutral today while we`ve been under the high, but once
it pushes east tonight we`ll enter a period of moderate to strong
WAA that will continue into Monday. A surface trough/weak cold front
will approach the area late this evening, but it will encounter a
very dry layer just above the boundary layer. Without much low level
moisture advection, this moisture-starved system (surface dewpoints
in the upper 20s to lower 30s) is will struggle to squeeze out much
precipitation over northern Michigan overnight. Models have also
been trending towards less QPF with this system, especially as it
moves east across the APX forecast area. Have therefore only gone
with low end chance to slight chance PoPs tonight. The 19.12Z suite
of deterministic models have all picked up on some possible weak
shortwave enhancement beginning around midday on Monday, mainly
affecting northern Lower south of M-32. So have continued slight
chance PoPs through the day Monday, focusing more across our
southern counties in the afternoon. Winds turning NW behind the
surface trough will quickly usher in a drier airmass Monday
afternoon that will lead to clearing skies.
Under the strong WAA developing tonight, temperatures will likely
experience a slight bump or at least hold nearly steady beginning
around midnight, then rapidly rise through the 40s Monday morning.
Highs will be in the low 40s across eastern Upper, ranging from the
mid 40s to low 50s across northern Lower.
Primary Forecast Concerns...A few rumbles of thunder will not be out
of the question late this evening, mainly along the Lake Michigan
shoreline south of the Leelanau Peninsula. Despite limited low level
moisture in place, PWATs will be around 3/4 of an inch there. This
will result in some elevated instability (generally above 700mb).
Not sold on forcing being strong enough to lift a parcel from that
level, though, so have not included thunder in the forecast. Recent
HRRR runs have shown some interesting 1 km AGL reflectivity
patterns, though, developing some weak cellular activity over Lake
Michigan. Other concern for tonight is the potential for some frozen
precip before the main push of WAA arrives. Depending on how fast
temperatures drop this evening, some locations over eastern Upper
may dip down to freezing as the precip arrives. Wouldn`t rule out a
bit of spotty freezing rain up there, but certainly nothing that
would be impactful. With evaporative cooling, there could be some
flakes mixing in with the rain early on across forecast area, but
the arrival of warmer temperatures would lend itself to primarily
rain after midnight.
&&
.SHORT TERM...(Monday night through Wednesday)
Issued at 337 PM EDT Sun Mar 19 2017
...Turning colder starting Tuesday afternoon...
High Impact Weather Potential: Minimal.
Pattern Forecast: Short range period starts in the wake of a cold
front that will cross Michigan during the day Monday...as the Great
Lakes lies along the southern gradient of a broad trough over
Manitoba/Ontario/Quebec with a couple of embedded short wave troughs
moving through the base of this trough. One such short wave trough/
jet streak will cross northern Michigan Tuesday...and drag a
secondary cold front across the area as a near 1040mb Arctic high
builds southeast into Manitoba/Ontario. This high will eventually
settle across the upper Great Lakes during the midweek period
(surface pressure over Michigan around +2 standard deviations for
mid March).
Primary Forecast Concerns: As mentioned above...short wave
trough/jet streak will be moving across northern Michigan Monday
night/Tuesday morning...with resultant height falls bringing a
second cold front (and more substantial push of colder air) into the
forecast area during the day Tuesday. In response...expecting an
increasing lake response as Tuesday wears on and cold advection
strengthens. This will initially occur over Lake Superior (along
with a diurnal component) with some clouds and perhaps some light
snow showers/flurries...then spread into northern portions of Lakes
Michigan/Huron with boundary layer flow having a substantial
northerly component. Tuesday temperatures should fall during the
afternoon across the eastern U.P...while expecting highs across most
of northern Lower to climb into the lower-mid 40s as next shot of
cold air not expected to arrive until closer to evening.
Coldest air will have settled across the region Wednesday morning
with 850mb temperatures in the -15C to -20C range...though will
moderate during the day...while Arctic high builds into Michigan.
Could be some lingering lake induced stratocumulus around...but for
the most part looks like a dry day with a fair bit of sunshine. But
it will be chilly by mid March standards with highs in the upper 20s-
lower 30s expected.
.LONG TERM...(Wednesday night through Sunday)
Issued at 337 PM EDT Sun Mar 19 2017
High Impact Weather Potential...Minor, but with a potential for a
wintry mix increasing Friday night.
At upper levels, a deep 500mb trough which dropped into the Great
Lakes earlier in the week, will exit east on Thursday while upper
ridging builds across the Great Lakes for the weekend. Mid level
temperatures will warm drastically across the region in response to
the building upper ridge, with 850mb temps of -10c early Thursday
warming to between +4c and +6c Friday and the weekend. This will
generate seasonal afternoon temperatures in the 40s across northern
Michigan through the period, maybe nearing 50 degrees Friday. At the
surface, a central Plains storm system will quickly lift across the
Great Lakes Friday while a large area of high pressure settles into
the Great Lakes for the weekend. Overall will continue with a dry
forecast through Thursday afternoon, with some wintry mix possible
into Saturday morning, followed by some sun and mild temperatures
for the weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1146 PM EDT Sun Mar 19 2017
Band of scattered relatively high based showers expected to move
across the area early this morning. MVFR producing cigs are
possible following these showers this morning. Will need to be on
the lookout for additional shower development today as a cold
front sweep through the region. Mostly light winds expected
through the period.
&&
.MARINE...
Issued at 357 PM EDT Sun Mar 19 2017
Southerly winds will increase tonight behind a departing high
pressure system. Late this evening and through early Monday morning,
borderline small craft advisory wind gusts will be possible over the
Lake Michigan nearshore waters, south of the Leelanau Peninsula. A
weak cold front will sweep through the region Monday morning,
causing winds to veer to the NW through the day. Stronger winds
develop over Lake Superior and Whitefish Bay Tuesday morning with
more widespread SCA winds arriving during the afternoon across the
Upper Great Lakes.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MSB
NEAR TERM...MEK
SHORT TERM...JPB
LONG TERM...SWR
AVIATION...MSB
MARINE...MEK
Area Forecast Discussion
National Weather Service Charleston SC
956 PM EDT Sun Mar 19 2017
...FROST ADVISORY ISSUED FOR PORTIONS OF INTERIOR SOUTHEAST
SOUTH CAROLINA...
.SYNOPSIS...
High pressure will build across the area through Tuesday. A cold
front will drop south through the area Wednesday as a wedge of high
pressure builds in from the north. The high will shift off the coast
Friday into Saturday. A storm system may affect the area next Sunday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
The boundary layer has quickly decoupled this evening and winds
have gone calm for all but the coastal corridor. Coastal winds
should subside over the next few hours as high pressure builds
south. Temperatures have fallen off quickly since sunset with
lower-mid 40s already being reported in the Walterboro-Huger
corridor as of 20/01z. High resolution guidance continues to
show much of interior Southeast South Carolina dropping into the
mid 30s prior to sunrise with dewpoints recovering to the
lower-mid 30s. This will support scattered frost early Monday,
especially along/north of an Allendale-Crocketville-Hendersonville-
Ravenel-Awendaw Line, but away from the Santee-Cooper lakes and
the I-26/I-526 areas in Charleston County. A Frost Advisory has
been issued for these areas from 4-8 am Monday. It should be
noted that both the H3R and RAP show some areas dropping to
31-32 degrees for 1-2 hours for the past several runs, but
confidence in this is not high enough to warrant a Freeze
Warning at this time. Opted to lower overnight lows another
degree or so for some areas, but keeping temperatures above
freezing. The rest of the forecast is on track.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Surface high pressure will slide over the area and then into the
Atlantic on Monday allowing for a sunny and pleasant day. A backdoor
cold front will slowly approach from the north Tuesday. Warm
advection and downslope flow will boost temperatures several degrees
above normal. Highs are expected to peak in the low to mid 80s
across most locations inland of the beaches. Any precipitation
should mainly stay to the north through the day, however maintained
slight chances in the extreme northern portions of the forecast area.
The cold front is progged to drop through the forecast area on
Wednesday. Shortwave energy and some increase in moisture will allow
for a chance of showers. Most of the activity looks to be post-
frontal, so thunder potential looks low at this time. A decent
temperature gradient expected as the southern portions remain in the
warm sector for a good portion of the day. Highs are forecast to
range from around 70 north to the low 80s south.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The high pressure wedge is expected to persist Thursday into
Friday before shifting east in response to a digging upper
trough to the west. Thursday looks the coolest, followed by
late-day warming on Friday. Saturday will most likely be warm
though Sunday could be unsettled as an upper low crosses the
Deep South.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
VFR.
Extended Aviation Outlook: Low ceilings possible late Wednesday into
early Thursday.
&&
.MARINE...
Tonight: The surface pressure gradient will relax tonight as
complex low pressure off the northeastern seaboard pulls away
into the Atlantic. Lingering thermal gradients will still
support 10-15 KT offshore. Seas will range from near 2 FT near
shore to around 4 FT closer to the Gulf Stream.
Monday through Friday: Quiet marine conditions will prevail early in
the week as high pressure prevails. A backdoor cold front will
slowly approach from the north Tuesday and then will cross through
the waters on Wednesday. Winds and seas will increase in its wake as
high pressure wedges down the eastern seaboard. Small Craft
Advisories will likely be needed for most if not all of the coastal
waters starting as early as Wednesday afternoon and persisting into
Thursday. Conditions are expected to improve on Friday as high
pressure shifts offshore.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Frost Advisory from 4 AM to 8 AM EDT Monday for SCZ040-042>045-
050-052.
MARINE...None.
&&
$$
Area Forecast Discussion
National Weather Service Cleveland OH
1047 PM EDT Sun Mar 19 2017
.SYNOPSIS...
High pressure over the Ohio Valley will move off to the east
tonight. A weak cold front will move southeast through the
region Monday evening, with a stronger cold front moving south
through the region Tuesday night. Arctic high pressure will
build in from the northwest Wednesday into Wednesday night
before moving east of the area Thursday.
&&
.NEAR TERM /THROUGH MONDAY/...
Update...Removed fog chances west half of the area. Bufkit shows
boundary layer flow increases through the night increasing the
potential for mixing. The upper level moisture will be
increasing as well ahead of the next system. As to pops...the
HRRR suggests rain may reach into extreme western CWA just
before/around dawn so put in a low chance pop. Other minor
adjustments to sky grids as well.
Original...Low clouds continue to hang around everywhere, with
the only exception being over parts of Lake Erie. We will likely
see at least some breaks in the clouds this evening with a
continued decrease in cloud coverage into the overnight hours.
Dry weather is expected tonight with partly to mostly cloudy
skies. Winds will remain light and turn out of the south
overnight ahead of an approaching weak cold front. We could
still see some areas of fog develop after midnight or so, though
whether the small amount of low-level moisture present
manifests as fog or low stratus clouds is still a little
uncertain. It will likely be a combination of both.
Rain showers will begin to move in from the west Monday morning
and continue to spread eastward through the afternoon hours.
This will occur ahead of and along the cold front, which is
progged to pass through the region Monday evening. Temperatures
should be able to rise to the middle and upper 40s ahead of the
frontal passage.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
The rain will be coming to an end from west to east Monday
evening into early Monday night. Temperatures will fall to the
lower and middle 30s in the wake of the front, but will recover
nicely Tuesday with highs in the middle to upper 40s. A few
southern and western locations may touch 50 degrees.
A weak disturbance will pass well south of the area Tuesday, but
may trigger a few rain showers across extreme southern portions
of the forecast area Tuesday afternoon into Tuesday evening.
A much stronger cold front will move south through the region
Tuesday night as an arctic high begins to build in from the
northwest. This will drop temperatures Tuesday night into the
middle 20s, with highs on Wednesday only reaching the lower to
middle 30s most places, and temperatures likely struggling to
get out of the 20s in northwest Pennsylvania. Can`t rule out a
few lake-effect snow showers/flurries Tuesday night across
northwest Pennsylvania behind the front, but the air mass is
quite dry, so only carried a slight chance.
A mostly sunny sky is expected Wednesday, with just a few
clouds moving in Wednesday night. The mostly clear sky Wednesday
night will allow temperatures to fall into the teens out east
and the low 20s across western areas.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
High pressure starting off the day overhead on Thursday will shift
to the east coast allowing southerly return flow to develop. An
increase in cloud cover is expected through the day with late day
highs approaching normal values for late March. Scattered showers
will accompany a warm front lifting north across the area Thursday
night into Friday morning ahead of the building ridge aloft.
Moisture axis will lift to the northeast on Friday with a break in
showers and temperatures warming into the 50s and low 60s.
Closed upper level low over the plains then expected to make slow
eastward progress through the Ohio/Tennessee Valley over the
weekend. Showers will return with temperatures being the more
difficult part of the forecast. The track of the low will influence
how long we stay in the warm sector before the cold front is pulled
back south with cool flow off the lake returning. Have followed a
blended forecast approach given the uncertainty with mild conditions
continuing on Saturday followed by a cool down on Sunday.
&&
.AVIATION /00Z Monday THROUGH Friday/...
The strato cu deck continues to erode from the edges. If current
trends continue...which is questionable...all of the area should
lose their low cigs overnight. At the same time high clouds will
continue to spill into the region from the NW. This should help
prevent fog from developing. A warm front will move over the
area on Monday. Expect MVFR cigs to return by early afternoon
with showers soon after. Light and variable flow will become
southeast overnight and southerly behind the warm front.
OUTLOOK...Non-VFR returns Monday night then again on Tuesday
night into Wednesday across NE Ohio/NW PA.
&&
.MARINE...
Favorable marine conditions are expected to continue on Lake Erie
through Tuesday. High pressure overhead will build to the
southeastern states with light southerly winds developing overnight.
A trough extending from low pressure near Hudson Bay will move
across the lake on Monday with a weak cold front settling south
Monday night. A stronger cold front will push south across the lake
on Tuesday night with northerly winds increasing to 15 to 20 knots
with waves near 4 feet. A Small Craft Advisory may be needed for a
window of time late Tuesday into Wednesday morning. Strong high
pressure will build south out of Canada behind the front with good
marine conditions returning on Thursday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Mottice
NEAR TERM...TK/Mottice
SHORT TERM...Mottice
LONG TERM...KEC
AVIATION...Kubina
MARINE...KEC
Area Forecast Discussion
National Weather Service Grand Rapids MI
1029 PM EDT Sun Mar 19 2017
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 325 PM EDT Sun Mar 19 2017
A cold front will move across the state Monday triggering some light
rain and perhaps a thunderstorms south of I-95. Dry and colder
weather is expected Wednesday with highs only in the mid 30s. Then a
warm up into the 50s will occur by the end of the week.
&&
.UPDATE...
Issued at 1028 PM EDT Sun Mar 19 2017
I have added the chance for thunderstorms to our western CWA
tonight as there is an area of elevated instability that shows up
nicely in the RAP soundings. The instability is coming from air
above 700 mb so nearly no chance of mixing this the ground but
above 700 mb there is 700 to 900 j/kg crossing the western CWA
between midnight and 4 am or so. This is on the nose of the best
1000/850 moisture transport. There are thunderstorms out there now
based on lightning data and surface observations (over NE WI and
soon northern Lake Michigan). Some brief down pours are surely
possible from these storms and small hail would not be out of the
question as there is a fair amount of the cape in the -10 to -20c
range.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 325 PM EDT Sun Mar 19 2017
Forecast concerns deal with pcpn chances later tonight and Monday.
A cold front currently over the Mississippi Valley will move east
through the cwa Monday. Ahead of it, instability has developed over
Missouri and some of this instability will move toward far southern
Lower Michigan tonight. We`ll see showers develop ahead of the
approaching front and a few elevated storms are possible tonight
south of I-94. Upper level support is lacking with this system; it
remains in Canada. Thus pcpn amounts will be limited. However, as a
wave develops along the front over Illinois tonight, moderate to
high pops seem warranted Monday. After the front passes, high
pressure quickly builds in and Monday night through Tuesday night
will be dry.
.LONG TERM...(Wednesday through Sunday)
Issued at 325 PM EDT Sun Mar 19 2017
The main challenge with the long term deals with the precipitation
type for Thursday night. The latest incoming data suggests this will
be mainly a rain event. The initially low wet bulb temperatures from
the High Res Euro...could support a brief period of snow...but the
warm air advection is strong and is shown to quickly warm up the
soundings...even for Harrison. The GFS is too warm for snow there
through the night with 800 mb dewpoints of 3.7 deg C at 06z for
Harrison. We will need to monitor the surface
temperatures...especially the interior northeast zones. The pattern
does suggest a small risk for zr if we end up with surface
temperatures a few degrees cooler.
It looks like a rather cool day for Wednesday. The 925 mb thermal
trough will be in place to start the day with values around -12 to
-13 deg C. Despite the abundant sunshine the weak flow with high
pressure overhead will support only slow modification of the
airmass. Some locations look likely to stay below freezing.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 731 PM EDT Sun Mar 19 2017
It would seem to this forecaster that for the most part the
showers will largely bifurcate the GRR TAF sites overnight. Some
of the convection is exiting northeast across Lake Superior as I
write this, that will stay well north of here. Meanwhile a
southern stream shortwave will track it`s convection largely south
of Michigan overnight. I could see a few scattered showers coming
through the AZO and BTL TAF sites even so. While an elevated
thunderstorm is not out of the question a quick look at the SPC
SREF makes is clear the thunderstorms will be south of I-94
overnight.
There is just the slightest hint that afternoon convection,
developing just north of the warm front associated with the
developing low over western IL could make it as far north of I-94
Monday afternoon, I did not play this in the TAFs but you should
be aware of this. If this makes it into Michigan these have a
better chance of being thunderstorms.
Once the convention misses the TAF sites to the south (more or
less) low clouds will follow and hold most of the day. Drizzle i
not out of the question. I would expect clearing around or just
after 00z Tuesday.
&&
.MARINE...
Issued at 325 PM EDT Sun Mar 19 2017
Southwest winds 10 to 20 knots will create 2-4 foot waves during the
next 24 hrs. A thunderstorm is also possible
&&
.HYDROLOGY...
ISSUED AT 1047 AM EDT SAT MAR 18 2017
RIVER LEVELS ARE RUNNING AROUND NORMAL TO A LITTLE BELOW NORMAL.
WITH LESS THAN A HALF INCH OF PRECIPITATION EXPECTED THROUGH THIS
WEEKEND AND THEN NO ADDITIONAL PRECIPITATION UNTIL FRIDAY, NO
FLOODING IS EXPECTED ACROSS THE AREA INTO NEXT WEEKEND. THE
PRECIPITATION NEXT WEEKEND MAY BE ENOUGH TO PUSH RIVER LEVELS UP,
BUT THEY SHOULD REMAIN BELOW BANK FULL.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...WDM
SYNOPSIS...04
SHORT TERM...04
LONG TERM...MJS
AVIATION...WDM
HYDROLOGY...63
MARINE...04
Area Forecast Discussion
National Weather Service Huntsville AL
808 PM CDT Sun Mar 19 2017
.NEAR TERM...(Tonight)
Issued at 807 PM CDT Sun Mar 19 2017
A fairly quiet weather evening as NW to SE oriented ribbon of
scattered low to mid level cloud cover (within the eastern flank of
a ridge axis centered over the northwest Southern Plains) moves
across the region. These clouds (mainly between 6-8 kft) are
overrunning a substantial dry air layer. This dry air layer has been
detected via 00Z RAOBs and GOES 16 WV imagery from the departing
anticyclone over the OH river Valley and oncoming anticyclone from
the Southern Plains. Though there have been some brief reflectivity
echos over central TN and northwest Alabama, any very light precip
that is occurring is likely evaporating as are the clouds. ECAMs and
HRRR models show the possibility of rainfall as moisture, warm air
advection, and weak omega values increase later tonight aloft and
again tomorrow as the ridge axis slowly shifts east. At this point,
not inclined to introduce POPs for late tonight with the now
dissipating cloud cover; and tomorrow morning due to the likely
slower moisture advection to the northeast and subsequent saturation
of the low-level profile before the lift moves northeast.
On the temperature and dewpoint forecast, only minor adjustments were
necessary. Did notice that the sky cover forecast appears to need
some tweaking for the current dissipating band of clouds, and
additional clouds that are expected early in the morning. Otherwise,
the rest of the forecast looks fine.
.SHORT TERM...(Monday through Tuesday night)
Issued at 240 PM CDT Sun Mar 19 2017
The warming trend continues on Mon, as weak upper ridging over the
mid/srn Plains states moves ever slightly to the e. Sly flow should
be well entrenched across the region as well, as Gulf moisture
streams back into the area. Highs on Mon look to rebound back into
the lower/mid 70s, before afternoon temps climb further on Tue, with
highs in the upper 70s/near 80F for most spots.
A weak cold front is still xpcted to approach the area from the n
heading into Tue evening. SBCAPE values during the day Tue look to
climb into the 1000-1500 J/kg range, as low level instability spreads
ewd ahead of the approaching sfc boundary from the n. Effective/Bulk
Shear values though are not that impressive along/just ahead of the
front, with values mainly around 30kt or less. Given a fairly linear
profile out of the w in the lower levels, a line of showers/tstms may
develop just ahead of the front during the afternoon/early evening
hrs Tue. Main wx hazards with any stronger storms look to be brief
gusty winds and perhaps some small hail, to go along with locally
heavy rainfall mainly along/n of the TN River. The tstm threat should
then weaken quite a bit going into the late evening hrs Tue, as
energy/instability wane with the loss of daytime heating.
.LONG TERM...(Wednesday through Saturday)
Issued at 240 PM CDT Sun Mar 19 2017
The weak cold front should then continue to drift swd into the local
area and diminish as the afternoon hrs progress Wed, as any low level
convergence along the front weakens and lingering mid/upper forcing
gets sheared to the se. Rainfall likewise should taper off to the s
heading into the afternoon period Wed, with the weakening cold front.
Relatively benign wx conditions are then xpcted Thu into Fri, as
another upper ridge pattern makes its way ewd across the cntrl Gulf
states and sfc high pressure out of the Great Lakes/OH Valley regions
drops into the mid Atlantic Coast.
The latter half of the global models are still hinting at a stronger
cold front and associated upper trough axis approaching the cntrl TN
Valley from the w heading into next weekend. Developing return flow
across the region should help usher further Gulf moisture back into
the area, as a low level sly fetch increases ahead of the oncoming
cold front. While buoyancy/instability look to be a tad bit weaker
with this next cold front late Fri into Sat, Bulk/Effective Shear
values still look to climb into the 40-50kt range given an increasing
sly fetch/low level jet. While some differences remain with the exact
strength/timing of this next front/storm system, multiple sfc waves
developing along the srn edge of the cold front may enhance the low
level curvature in the wind profile, provided the inflow into the
area is not diminished from the s. Pending model runs over the next
couple of days will hopefully provide a little more clarity going
into Fri/Sat. Nevertheless, showers/tstms should certainly be on the
increase along/ahead of this next front, as it begins to move ewd
across the local area during the first half of the weekend period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 613 PM CDT Sun Mar 19 2017
VFR conditions are expected across N AL/S Middle TN for the next 24
hours. Low-cloud cover that may move over the TN Valley should remain
on the low end of VFR. In addition, there could be some light -DZ/-RA
late in the period (between 20/15Z-21/00Z) but very isolated in
nature. Thus, did not include in forecast at this time.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...SL.77
SHORT TERM...09
LONG TERM...09
AVIATION...SL.77
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service Lincoln IL
850 PM CDT Sun Mar 19 2017
.UPDATE...
Issued at 837 PM CDT Sun Mar 19 2017
Current forecast is on track. HRRR still forecasting the
enhancement of the LLJ over Missouri and into Iowa through the
remainder of the evening. As the strong moisture advection riding
the jet impacts the effective boundary over Iowa significant lift
is expected. MUCape is already running over 1000 J/Kg in that area
per SPC Mesoanalysis, but bufkit soundings show that convection
will remain elevated with a nice inversion in place below the warm
advection, thereby limiting impacts to potential hail.
HRRR 23Z and 00Z are showing development in the 1-2 AM window in
eastern Iowa and then system expanding SE into the northern half
of the forecast area. The model trend is a bit further south than
the previous runs and will have to be watched closely.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 247 PM CDT Sun Mar 19 2017
Temperatures have reached the 50s across the forecast area by 2 pm,
despite the bands of mid and high clouds drifting through. Scattered
showers and thunderstorms continue to trudge eastward across eastern
Missouri. Latest RAP model does have the northern edge of the
showers clipping areas around Jacksonville by late afternoon, while
the HRRR and NAM-Nest keep it just to our southwest. May need to add
some slight chance PoP`s over the far southwest CWA for a few hours.
Main concern remains with the overnight convection. Latest surface
map showing low pressure centered over north central Nebraska, with
a frontal boundary extending northeast into southeast Manitoba. With
time, this boundary should focus more into a warm front over Iowa as
the low moves eastward. A low level jet will focus along this
boundary and lead to some convection developing by late evening over
eastern Iowa. The GFS has been very aggressive with development and
bringing it into the northwest CWA as early as 9-10 pm, but am
thinking that a post-midnight arrival is more likely. Steep mid-
level lapse rates of around 8C/km will likely result in some hail
with the stronger storms, with the SPC Day1 outlook featuring a
marginal severe weather risk over the northern third of the CWA.
How much of this lingers into Monday is also a question. While the
initial band of showers/storms shifts into Indiana early Monday, the
high-res models try to develop some additional convection over the
eastern CWA with the arrival of the front itself early afternoon. A
little MUCAPE remains by this point, but will be on the wane, so
will only mention isolated thunder over the east in the afternoon.
Temperatures over a good chunk of the CWA should manage to reach the
60s ahead of the front, but have kept areas from Bloomington to
Danville in the mid-upper 50s as the clouds and rain will be a
bit more prevalent there.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 247 PM CDT Sun Mar 19 2017
A cold frontal boundary will slowly drop into southern Illinois
Monday night, shifting the focus for rain south of our forecast
area. A fast moving shortwave will trigger a period of showers
Tuesday into Tuesday evening, with Likely chances of rain focusing
on Tuesday afternoon during peak forcing for precip. The ECMWF
continued its southern bias with the band of rain across our area as
opposed to the GFS and NAM farther north expansion of rain. However,
most of our forecast area should see at least light rain.
Canadian high pressure will suppress that wave and residual moisture
southward later Tuesday night, setting up a chilly but mostly sunny
day for Wednesday. Low temps Wednesday night are expected to dip
below freezing in most areas in the cold air mass, despite
increasing cloud cover.
Southerly return flow will become established behind the departing
high pressure later Wed night, with a few light snow showers
possible in our far western counties around sunrise on Thursday. The
warm advection band of precip will lift north through Illinois on
Thursday, changing snow chances to rain by Thursday afternoon. Dry
conditions are expected to re-develop Thursday night as central IL
enters the warm sector. Rain chances will ramp up again Friday
afternoon as a developing low pressure center approaches Illinois
from the Plains. There is better agreement in the extended models
showing the low passing across Illinois on Saturday afternoon and
Sat evening, with likely to categorical PoPs across the board during
that time. Instability and low level moisture supply appear
sufficient for thunderstorm development, especially Friday night and
Sat morning.
The slow moving nature of the low per the GFS and Canadian caused
the extension of precip chances into Sunday morning, with a few
showers southeast of I-70 Sunday afternoon.
Friday continues to look like the warmest day of the next week, with
highs in the mid to upper 60s. Depending on the speed of the low
pressure center next weekend, highs could reach the low 60s on
Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 620 PM CDT Sun Mar 19 2017
Remnant clouds from earlier convection over Missouri will bring
some VFR CIGS briefly to KSPI over next few hours. Otherwise, VFR
conditions will likely hold until around sunrise or so. Exception
will be near any thunderstorms that develop after 06z tonight.
There is still some range in model solutions with the GFS the most
robust at developing widespread precip this evening. This seems
questionable given the lack of trigger and location of short-wave
ridge axis over Illinois. Most of the convective allowing models
support an area of elevated convection developing to our north and
then saging southward into the area after 07z. Given the
forecasted location of the LLJ and the boundary at that level this
seems to be a more realistic evolution and will generally be
followed.
The cold front associated with the initial wave is expected to
push across the area Monday afternoon. Ahead and along the front
MVFR CIGs appear possible with even some IFR conditions
temporarily at KBMI. Conditions should improve after the frontal
passage toward the end of the TAF valid period.
170-220 winds should remain gusty ahead of the front overnight and
Monday with occasional gusts to around 20 knots. Expect 350-040
winds around 10 kts after passage.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barker
SHORT TERM...Geelhart
LONG TERM...Shimon
AVIATION...Barker
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
925 PM CDT Sun Mar 19 2017
.UPDATE...
922 PM CDT
No significant changes to going forecast though did nudge highest
PoPs a little farther south to reflect latest model trends and
expected placement of the low level jet. Scattered high based
showers are moving southeast across Wisconsin this evening ahead
of a cold front, and a couple thunderstorms have been able to
develop ahead of the front farther north in Central Wisconsin.
It`s possible to see some precip across northern Illinois within
the narrow and weak instability axis, but better dynamics are in
place across central and northern Wisconsin and think there is a
better chance for areas north of the I-88 corridor in Illinois to
remain dry this evening.
Main focus this evening and tonight though will be increasing
convection associated with a low level jet to our west/southwest.
Guidance has been somewhat consistent this evening indicating the
low level jet setting up across Missouri into far southeastern
Iowa this evening with convection increasing around or just after
midnight. Latest SPC meso-analysis and 00Z DVN Raob indicate
strong MUCAPE in excess of 1000 J/kg just west of the CWA.
Meanwhile, LLJ is progged to ramp up over the next couple hours
with strongest moisture convergence focused from far NE MO/SE IA
southeast into central IL. Expect this will be the region of
strongest convection with storm motions off to the ESE. Think that
greatest severe threat will stay closer to the LLJ convergence to
our west/southwest where the highest instability will be in place
which quickly decreases farther east. This should result in a
fairly minimal severe threat for the local CWA with elevated
hailers still the primary concern for any stronger storms that are
able to persist into the local area. As mentioned earlier, nudged
the highest PoPs farther south given the aforementioned thoughts
with support from latest runs of the HRRR and RAP which are
trending slightly farther south as well.
Deubelbeiss
&&
.SHORT TERM...
210 PM CDT
Through Monday...
After a pleasant and seasonal (though cool at the lake) Sunday
with partly cloudy conditions and modest winds, our focus will
shift to shower and thunderstorm chances tonight into Monday.
A lead shortwave riding the periphery of a flattening ridge across
the plains is leading to convection along a warm frontal boundary
across Missouri. This activity will dissipate, but additional
shortwave energy will propagate east along the frontal boundary
in an area of increasing moisture return ahead of significantly
increasing southwesterly low level jet. At this point the best
moisture return and theta-e advection will be across our
southwestern counties where the latest high- resolution guidance
is suggesting an expansion of shower and thunderstorm coverage
tonight. Initially this will be focused across Iowa this evening,
but the RAP/HRRR suggest enough moisture convergence north of the
front and some decent elevated instability to suggest a swath of
showers and storms in our area. The favored areas for storms will
generally be south as the night progresses toward daybreak. The
instability is enough to be concerned about some severe hail with
the instability extending through the hail growth region and
decent shear though marginal in the cloud bearing layer, and
therefore the threat is marginal and consistent with the SPC
outlook. The main focus will be after midnight into early Monday,
with better chance of hail largely southwest of the core of the
Chicago metro area based on latest convective allowing model
guidance, but it is certainly a non-zero threat farther north.
The shortwave trough axis will approach Monday morning with the
cold front, which will likely continue the chance of showers
during the morning hours, possibly redeveloping for our northern
areas including the Chicago area. The main warm frontal boundary
will generally slide east along our southern counties, thus we
never truly get into the warm sector ahead of the low. And while
the northern stream cold front will shift into northern Illinois
later morning, it will take a bit longer south which will linger
the shower chances for most of the day for these areas. Expect
cooling in Illinois, especially lake areas in the afternoon. The
instability axis gets shoved farther south but not completely out
of the area until the cold front arrives, so will need to hang
onto the thunder mention into the morning and it is possible the
marginal risk may have to shift north a bit on Monday.
KMD
&&
.LONG TERM...
259 PM CDT
Monday night through Sunday...
More energetic shortwave energy and associated precip will shift
south of the CWA by Monday evening, with high pressure expected to
build across the area Monday night into Tuesday. Cold advection
on the backside of this system will return a cooler/drier air mass
to the region, especially by Tuesday. Next chance of precip does
appear to be on Tuesday, although confidence is lower with this
chance owing to some placement and timing issues. Upstream
shortwave anticipated to drop southeast through the region during
this time, as baroclinic zones tightens up. With this setup, a
narrow axis of developing precip seems probable and at this time,
a favored location would be over the southern CWA. Expected
highs/boundary layer conditions would support all liquid at this
time, but will continue to monitor for at least a low potential
for a rain snow mix. With anticipated colder thermal profile
aloft, it looks like if enough forcing were to occur to cool the
entire profile, then snow could be possible. Too early to tell at
this time though, and have maintained only rain for Tuesday. Any
precip then sags southward Tuesday evening with further expansion
of the high to the north. Much colder air filters south and with
this high moving more overhead, Tuesday night is looking to be a
chilly night. However, the CWA may stay on the outer fringe of
this high and tighter gradient. This would allow the winds to
possibly stay more elevated and lessen the extent of the cooling
this night. Dry weather then expected to continue Wednesday into
Wednesday night. Large scale pattern begins to change though, with
upper level ridge building overhead and warmer air returning to
the region. Warmer temps expected Thursday and Friday, but
precip/rain and possibly thunder chances increase by late Thursday
into Friday.
Rodriguez
&&
.AVIATION...
For the 00Z TAFs...
Multiple aviation concerns, with the higher confidence on low
clouds developing Monday morning and lingering into the afternoon.
For the Chicago area airports, the overall concerns are:
- Likelihood of scattered TSRA in the region overnight, most
favored southwest of the airports, though could be close.
- Possibility of another round of -SHRA and some thunder late
Monday morning into the early afternoon.
- IFR cigs and MVFR visibility likely at some point Monday
morning into early afternoon, with LIFR cigs possible.
- South winds tonight becoming northeast early Monday afternoon,
likely overlapping IFR cigs.
Scattered thunderstorms are expected to develop across
southeastern/eastern IA and western and possibly northwestern IL
by 06Z. This activity will translate southeast, so whether or not
it impacts the TAF sites will depend on just how far north it
develops. No matter what, the higher coverage and deeper tops are
probable to be southwest of the TAF sites.
Diminishing wind speeds on Monday morning will allow for ceilings
to lower to IFR with high confidence, however, the rate in which
this drop occurs has low confidence in the forecast. Gradually
lowering visibility is also likely during Monday morning, though
dense fog is not favored at this time. As a cool front approaches,
the possibility of showers/rain increases in the 15Z-20Z window
before this activity shifts southeast.
The cool front passage will turn winds northeast with medium-high
confidence in speeds over 10 kt, and the timing of the wind shift
has medium confidence. Clouds will likely remain IFR given flow
off the lake.
MTF
&&
.MARINE...
259 PM CDT
High pressure which has been situated across the lake for much of
the day continues to shift to the east at this time. This trend
will continue this evening and tonight with winds expected to
quickly increase this afternoon. Expect winds of up to 30 KT to be
in place by this evening over the north half with winds of 15 to
25 KT expected over the south half. Winds should stay in the 10 to
20 KT range along the nearshore tonight. The gradient and winds do
weaken by early Monday morning, but anticipate speeds to increase
once again later in the day Monday as a wind shift to the north
occurs. Although some slight variation may occur, expect northerly
winds to persist Monday night into Tuesday with an increase in
speeds expected once again. Speeds Tuesday night into early
Wednesday could reach gales for a time. Confidence is low at this
time, and so have maintained mention of 30 KT in the open water
forecast.
Rodriguez
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
734 PM EDT Sun Mar 19 2017
.SHORT TERM...(This evening through Monday)
Issued at 341 PM EDT SUN MAR 19 2017
Strong upper trough moving from northern Manitoba to Hudson Bay will
push deep 987mb low from far northern Manitoba to southern Hudson
Bay by 12z Mon while deepening to 976mb. Sfc trough tied to the low
extends south to southern Mantioba and eastern North Dakota. Warm
front extends from that trough to the central Plains. SSE flow ahead
of trough is graudally bringing in warmer conditions, though it has
been a slower rise over Upper Michigan as flow is mainly coming off
Lk Michigan and there are sct-bkn middle clouds. Soundings upstream
indicated steeper mid-level lapse rates but they were also dry below
moist layer h7-h5. Stronger shortwave stays north of Lk Superior
this evening but tail end of that wave along with increasing h85-h7
moisture advection moving in from the west. That forcing along with
instability aloft results in isold-scattered showers developing over
MN and then moving across Lk Superior and Upper Michigan through the
evening.
Certainly does not feel like a thunder day outside attm as it cooler
and dry, but if convection can develop late this aftn into this
evening there could be thunder with mid-level lapse rates over
8c/km and RAP and HRRR indicating mucapes up to 400 j/kg.
Conditional potential but with low freezing levels would not take
much to get small hail in even the stronger showers. Strong winds
aloft with h85 winds up to 50 kts but think risk of having these
winds surface is low as all the shra and any tsra would be based
at h7 or 8-10kft. All precip should be clear of eastern cwa by
06z, though low clouds and/or fog may linger through much of
night. Best chances of fog would be over cntrl and east.
Low pressure trough crosses late tonight switching winds to the NW
on Monday. Low clouds will give way to plenty of sunshine in the
aftn as drier air moves in as large high building over cntrl Canada.
Cooler air gradually moves in but most areas should be able to reach
the 40s. Could even be warmer over the scntrl with downslope NW
winds and as there is little if any snow cover left. For those
areas, mixing to h85 temps 1-4c supports max temps reaching into
the low 50s.
.LONG TERM...(Monday night through Sunday)
Issued at 249 PM EDT SUN MAR 19 2017
Models suggest that a progressive pattern will prevail into next
weekend. After a brief cooldown from Tue into Wed with n-nw flow
LES, moderating conditions will follow by Thursday into Friday as a
low pressure system with widespread precipitation moves affects the
region. Temperatures will drop behind the system but should still
remain at or above normal.
Monday night through Wednesday, a shortwave trough sliding through
nrn Ontario will drag an arctic front through the nrn Great Lakes
Tuesday morning with much colder air dropping into the area on nnw
winds. 850 mb temps are expected to fall to around -18C by 00z/Wed
which will provide enough instability for LES development. However,
LES intensity will be limited by relatively low inversion heights
around 4k-5k ft with a very dry 850-700 mb layer and very dry low
level air upstream. The LES should diminish Wed morning as winds
become light and anticyclonic as the dry airmass associated with
1040 mb high pres builds into the region. Expect Snowfall amounts in
the 1 to 2 inch range per 12 hours at most and SLR values above 20/1
with DGZ through the convective cloud layer.
Thursday-Sunday, Model/ensemble spread is still relatively high with
the evolution of the cntrl plains shortwave and sfc low heading
toward the Great Lakes. The ECMWF and CMC slide the stronger 500 mb
low more to the east. There is still decent moisture transport
toward the cwa and support for pcpn with a nrn stream shrtwv and
fgen associated with the right entrance of the jet from nrn Ontario
into Quebec. This would still keep the heavier pcpn and warmer air
farther south compared to the GFS/GEFS. However, there is enough
agreement to maintain high pops for mixed pcpn that would likely
change to rain Friday as a warm layer spreads into the cwa. Some
snow or lake enhanced snow may be possible as colder air moves in
behind the system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 734 PM EDT SUN MAR 19 2017
Ahead of a low pres trof moving across the area overnight/Mon
morning, a band of sct -shra currently exiting western Upper MI will
affect central Upper MI, including KSAW, for the next couple of hrs.
Not expecting conditions to fall blo VFR in the shra, though some
shra could produce grauple/small hail and potentially a lightning
strike. After the pcpn ends, lower clouds/fog may eventually develop
at KSAW. For now, only lowered conditions to MVFR, but not of the
question for conditions to fall to IFR. With the passage of the
trof, conditions should improve quickly to VFR Mon morning. At
KIWD/KCMX, low-level jet ahead of the trof will lead to LLWS this
evening. Otherwise, VFR conditions are expected to prevail at both
terminals thru the fcst period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 341 PM EDT SUN MAR 19 2017
At this time, no gales or heavy freezing spray are expected through
this week. Prevailing winds will mostly be in the 20-30 kt range.
Strongest winds will be Mon night into Tue evening as cold air moves
across Lk Superior.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLA
LONG TERM...JLB
AVIATION...Rolfson
MARINE...JLA
Area Forecast Discussion
National Weather Service Shreveport LA
1058 PM CDT Sun Mar 19 2017
.DISCUSSION...
Just sent out a quick update to extend patchy fog wording
northward to include Monroe and El Dorado based on HRRR
visibility guidance. Fog development expected around daybreak.
Update already out. /05/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 61 87 60 87 / 0 0 0 0
MLU 59 86 58 85 / 0 0 0 0
DEQ 58 84 56 84 / 0 0 0 0
TXK 62 85 58 84 / 0 0 0 0
ELD 59 86 56 85 / 0 0 0 0
TYR 63 87 61 86 / 0 0 0 0
GGG 61 87 61 86 / 0 0 0 0
LFK 61 87 60 87 / 0 0 10 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
05