Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/16/19
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
806 PM CDT Tue Oct 15 2019
Issued at 803 PM CDT Tue Oct 15 2019
Will make a few tweaks to sky cover and temps, but in general the
forecast is panning out about as expected. Therefore, no major
changes are expected this evening.
.SHORT TERM...(This Evening through Wednesday Night)
Issued at 252 PM CDT Tue Oct 15 2019
The forecast challenge is how long to hang on to sprinkles/drizzle
mention tonight, along with the impact cloud cover will have on
Currently, other than a few breaks in the stratus layer across the
Missouri River valley, cloudy skies dominate the weather picture
this afternoon. Winds are breezy to windy out of the northwest and
temperatures range from the upper 30s to the upper 40s. The upper
level low pressure system churning its way southeast through the
region, has produced some pockets of very light rain
showers/sprinkles, as well as some areas of drizzle, across mainly
northeast South Dakota/west central Minnesota today. In fact, this
activity is ongoing, and likely to persist into early this evening.
RAP output fed through BUFKIT suggests the depth of the stratus
layer may shallow out enough by 9 or 10 pm CDT this evening to
preclude any further mention of drizzle/sprinkles. Something for the
evening shift to mull over.
Short range guidance progs an area of high pressure over the
northern high plains/front range to work its way east into the
Dakotas overnight. Short range guidance also seems to think forcing
along with strength of winds and low level dry air advection will
send the western edge of the stratus clouds eastward toward the
James River valley overnight. Areas that clear off out west
overnight will see surface winds going light and variable at about
the same time. This should help temperatures across the Missouri
River valley to cool down into the 20s to near 30 degrees. Overnight
lows further east under a more persistent overcast condition will
likely remain in the 30s.
As high pressure at surface and aloft works across the region
Wednesday into Wednesday night, return flow winds/pressure pattern
gets going from west to east. Much warmer air begins advecting into
central South Dakota on Wednesday, spreading up across northeast
South Dakota and west central Minnesota Wednesday night on southerly
winds. Wouldn`t be surprised to see a decent downslope wind event
setting up Wednesday night in the lee of the Prairie Coteau under
this set up.
.LONG TERM...(Thursday through Tuesday)
Issued at 252 PM CDT Tue Oct 15 2019
Main features to focus on in the extended include a weak trough
passage Friday and a more robust system to close out the weekend and
for the start of next week. This second feature will give us the
best chance for moisture through the forecast period, however given
the timescale (days 5-6-7), and the wide array of deterministic and
ensemble outcomes, confidence with the overall handling of this
system remains low. Despite this, p-type has mostly trended towards
rain and thus generally the overall threats from the system will be
So, back to Thursday/Friday`s system, which will feature southeast
low level flow initially. Low pressure and associated shortwave move
into the western Dakotas around midnight, and proceeds east through
the morning and into the afternoon, departing the eastern CWA around
21Z. Forcing and low level moisture is generally lacking with this
feature, with mid/high based clouds that could generate some
sprinkles but otherwise dry. Winds will increase for the Coteau
downslope area briefly as low level flow shifts to the southwest but
that is followed by a more west/northwest trajectory. Mixing ahead
of the front is expected to aid in warming, so have notched up
temperatures a few degrees over blended guidance for the James
valley and east of the Coteau. A favorable mixing direction and weak
cold advection will continue into Saturday so wouldn`t be surprised
if were a little conservative for highs in the James valley.
Favorable mixing will also influence winds Friday/Saturday, though
blended guidance is just a few kts below higher end guidance so at
this time no adjustments were made.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 617 PM CDT Tue Oct 15 2019
MVFR cigs will likely persist well into the night across the
eastern part of the area, but the west should be mainly VFR. Vsbys
will generally favor VFR region-wide through tonight.
Area Forecast Discussion
National Weather Service Bismarck ND
946 PM CDT Tue Oct 15 2019
Issued at 929 PM CDT Tue Oct 15 2019
Lower stratus clouds have been clearing east at a rate of 15 to
18 mph with the western third now pretty much clear. Some high
clouds are also moving in from Montana. Temperatures have been
falling in the clearing areas to the west, and have been more
steady central and east.
As the h850 warm advection continues and strengthens overnight the
stratus will clear through the region, with patchy fog then
forming after midnight over the snow covered areas. Temperatures
will be challenging with the snow and possible fog creating micro
climates tonight. Overall we left teh min temperatures in place.
On Wednesday, more sunshine and much warmer temperatures will
accelerate the snow melt. We raised the highs southwest and west
central into teh mid 60s Wednesday where the 50th percentile of
the MOS guidance places it and where the lake of snow cover fits
the warmer scenario.
UPDATE Issued at 606 PM CDT Tue Oct 15 2019
Large stratus area currently associated with low level moisture
and the low level baroclinic zone. As low level warm advection
becomes more predominant the stratus will slowly erode. However,
surface moisture over the snow covered areas should promote some
fog formation. Then mid level warm advection will begin to
increase clouds over the west and central late tonight and
Wednesday. Current forecast looks ok.
.SHORT TERM...(This afternoon through Wednesday)
Issued at 209 PM CDT Tue Oct 15 2019
Latest satellite imagery and surface observations continue to
show stratus being maintained with the exception of a few breaks
from time to time across western/central ND. Water vapor imagery
and BUFKIT soundings show drier air/subsidence through most of the
column, except below 850mb/5kft. Within the low level moist layer,
where breaks in the overcast have become established, a few showers
are trying to form as there are decent low level lapse rates and
weak vertical motion per RAP BUFKIT soundings. However they have
been very short lived and sporadic in nature. Thus, will not carry
any PoPs this afternoon as duration and location remain short and
random. Low level warm air advection will commence southwest this
evening and gradually propagate into south central ND after midnight.
Increased upward vertical motion will initially allow some drier
air aloft to mix through the low level moist column/below 5kft,
but at the same time will also allow an inversion to develop near
the ground given the snow cover and high moisture. Will likely see
fog/stratus redevelop where clouds thin out for a time, and so
have added in areas of fog mainly south central overnight. For
Wednesday, clouds in the morning associated with a ribbon of warm
air advection/upward vertical motion will continue to propagate
east, allowing for a decrease in clouds from west to east. Highs
Wednesday will range from the lower 60s west to the colder mid
30s in the Turtle Mountains with deeper snowpack.
.LONG TERM...(Wednesday night through Monday)
Issued at 209 PM CDT Tue Oct 15 2019
Warmer air will continue to overspread most of western and central
ND through Thursday with highs in the mid 40s Turtle Mountains to
the upper 60s west. The next upper trough and associated cold front
arrives Friday with a slight chance of rainshowers. For the weekend,
the GFS continues to come more in line with the ECMWF, which continues
to swing an upper and surface low closer to eastern North Dakota than
previous runs. This suggests a decent swath of rain is possible across
central ND Sunday afternoon through Monday. There is some potential
for up to around 1 inch of liquid in the James River Valley with
this system. The majority of the precipitation looks like rain given
the 850mb temperatures, but some snow is possible at times, especially
as the system exits Monday.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 606 PM CDT Tue Oct 15 2019
Widespread MVFR conditions associated with stratus clouds will
gradually erode from west to east tonight. However areas of fog
are expected to form over the snow covered areas, impacting KBIS-
KJMS after 06z with IFR conditions. Expect conditions to become
VFR KISN- KDIK after 02z, KMOT after 10z, and KBIS-KJMS after
Area Forecast Discussion
National Weather Service Caribou ME
920 PM EDT Tue Oct 15 2019
High pressure will move east of the region tonight and Wednesday.
Low pressure will intensify off the Mid-Atlantic coast
Wednesday night and quickly track north into the Gulf of Maine
Thursday morning. The low will continue northeast across the
Maritimes Friday. High pressure will return Saturday and Sunday.
.NEAR TERM /THROUGH WEDNESDAY/...
9:20 PM Update: A surface ridge extends from off the southern
New England coast north into Maine. The ridge will slide slowly
east overnight. Clear across the FA, but upstream cirrus will
spread east across the area overnight. By daybreak, there will
likely be a broken deck of cirrus across northern areas with
less in the way of cirrus toward the coast. Temperatures as of
9 PM have dropped into the low to mid 30s in most of the
northern and central valleys and into the upper 30s in the
colder valleys Down East. Did make some adjustments to the
hourly temperatures and to lower the lows a few to several
degrees. Otherwise, the forecast is on track.
Calm before the storm so to speak.
Broad upper trof moving across the region this afternoon as seen
on the 12Z UA will be east of the region by evening w/high pres
moving in from the west. Clouds will dissipate w/winds dropping
off leading to a good radiational cooling night. Temps are
expected to drop off quickly after sunset w/overnight temps
dropping into the upper 20s and lower 30s across the far north
and west. Elsewhere, temps will generally be in the 30s. This
matches the midnight crew`s thinking. The caveat to all this
will be the high clouds shown by the short range guidance
including the GEM/NAM and RAP to advance into northern areas
overnight. This would halt the progression of any further drop
in temps. For now, brought sky percentages to 60-70% and leaned
w/the high clouds being partially thin allowing for some
cooling. Collaborated w/GYX on going w/river valley fog given
the relatively warm river/stream waters.
For Wednesday, high pres is expected to push to the east in the
morning with some high clouds across the northern 3rd of the
CWA. The NAM and GEM were consistent w/showing the ridge axis to
push in by early afternoon w/clouds dissipating, leading to some
sunshine and a tad warmer reaching near normal readings. Winds
will be slowly picking up from the south during the day. Clouds
are expected to be back on the increase later in the afternoon
in advance of the strong storm. Given the ridge axis holding in
the afternoon, decided to push back rainfall percentages in the
western and southwestern areas til Wednesday night. More on this
in the Short Term section below.
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
High pressure will slide east of the Maritimes Wednesday night as a
deep trough of low pressure tracking through the Great Lakes
supports primary low pressure over the eastern lakes and secondary
low pressure developing off the Mid-Atlantic coast. A strong jet max
surging through the base of the trough over the Carolinas will
support intensification of the Mid-Atlantic low Wednesday night as
it tracks up off southern New England and toward the Gulf of Maine.
A strengthening pressure gradient ahead of the approaching low and
behind departing high pressure will bring a rapidly increasing
easterly wind Wednesday night with the strongest winds arriving by
predawn Thursday morning Downeast. Rain will spread into the
Downeast region after midnight and reach the north before dawn
Thursday morning. Wind along the Downeast coast early Thursday
morning may approach 20 to 30 mph with some gusts near the coast up
to 45 mph. This may result in scattered power outages Downeast. By
midday Thursday the low center will be near the coast and most of
the steady rain will be over northern areas. Drier air circulating
into the mid levels of the system will likely taper off the steady
rain Downeast by Thursday afternoon leaving spotty showers or
drizzle. The low will begin to occlude by the end of the day
Thursday as precipitation tapers off to showers over the entire
region. The low will continue northeast into the Maritimes later
Thursday night into Friday as lingering clouds, spotty showers and a
gusty northwest wind continue behind the system over our area.
Clouds may begin to break up late in the day. Some sunshine is
possible Downeast before the end of the day on Friday.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A gusty northwesterly breeze will continue Friday night as the low
continues to track away through the northeastern Maritimes and high
pressure begins to build in. The high will start to build over the
area Saturday bringing a mostly sunny, more tranquil and seasonably
cool day. This will be followed by a mostly clear and tranquil night
Saturday night. The calm air and light winds will likely allow some
fog to form by Sunday morning. High pressure nearby to the south and
upper level ridging over the area will bring a mostly sunny and
tranquil day Sunday followed by a clear night Sunday night. High
pressure will slide off to the east on Monday as the next trough and
associated low begins to approach from the west. This will bring
sunshine Monday followed by increasing clouds Monday night with a
chance that showers will begin to spread into the area late Monday
night as an occlusion approaches. A southerly breeze will increase
ahead of the front Monday night. The front will push into the area
Tuesday with a strong southerly breeze and showers. The showers
should slide east of the area Tuesday night and clouds may break up.
A few showers are possible with a weak cold front on Wednesday.
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: High pressure, mostly clear skies, and light winds
will lead to potential for patchy river valley fog late tonight
at sites such as PQI and HUL. Some minor LLWS is also possible
overnight north of KHUL between the near-calm surface layer and
20 knots just above the nocturnal inversion. VFR conditions
prevail Wednesday with winds shifting to S/SSE as return flow
develops ahead of the upcoming storm system.
Wednesday night: VFR early, lowering to IFR from south to north.
Rapidly increasing east winds becoming strong by morning.
Thursday: IFR in windswept heavy rain. Strong northeast winds. Wind
and rain diminishing Downeast Thursday afternoon.
Thursday night: IFR. Strong north winds becoming northwesterly.
Friday: IFR becoming MVFR, and possibly VFR Downeast late. gusty NW
Saturday: VFR. Northwest winds diminishing.
Light winds less than 10 kts w/seas 1-2 ft. Winds and
seas will be increasing on Wed as the wind direction shifts to
the se at 10-15 kts and seas start building to 2-4 ft by later
in the afternoon.
Winds will rapidly increase from the east Wednesday night likely
reaching storm across the offshore waters and gale on the
intracoastal waters after midnight as intensifying low pressure
approaches. Storm/Gale will continue early Thursday morning with
winds diminishing Thursday afternoon as the low center tracks
over the waters. A gale watch remains in effect for the
intracoastal waters with a storm watch now in effect for the
offshore waters. Strong gusty NW winds are expected Thursday
night into Friday. Winds will diminish later Friday night into
MARINE...Gale Watch from late Wednesday night through Thursday
afternoon for ANZ052.
Storm Watch from late Wednesday night through Thursday
afternoon for ANZ050-051.
Area Forecast Discussion
National Weather Service Charleston SC
1005 PM EDT Tue Oct 15 2019
A stationary front will remain over the area as low pressure
moves through tonight and Wednesday. High pressure will prevail
Thursday and Friday, then Gulf low pressure may bring unsettled
weather next weekend.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Convective rains will continue to increase in both coverage and
intensity the rest of the night as a pronounced southern stream
shortwave will move through from the west. Forcing ahead of
this feature along the stationary front across the area will
allow for a wave of low pressure to form as it tracks across
southeast Georgia and southern South Carolina overnight. There
remains disagreement on the exact track of the surface low, with
some models having it pass inland, with others closer to the
coast, before it shifts into the ocean toward daybreak or
There are more reports of heavy rains just upstream from the
forecast area, and several hours straight of the RAP and HRRR
are showing 2-4 inches from near Tybee north to southern
Charleston County through 12Z Wednesday. The 00Z NAM has 1.5 to
3 inches, while the 18Z HREF also had a solid area of 2-3
inches in this same general vicinity. Thus we have felt
compelled to add mention of heavy rains at times after midnight,
mainly south of I-16 in georgia prior to 06Z, before it spreads
north along the coastal corridor into South Carolina later
Despite the lack of significant surface based instability, a
few t-storms can still occur given the strong dynamics, with the
risk generally near and south of I-16 in Georgia and along the
coastal corridor into South Carolina after midnight.
Temps won`t change much through the night, and breezy conditions
will develop along and near the shore late as gusts reach 25-30
mph as the wave of low pressure moves across the area.
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
The surface low will be moving through southern SC Wednesday
morning, bringing a quick end to the ongoing precipitation. Most
areas should be rain-free by early afternoon due to dry air
advection and subsidence. We maintained a slight chance for
thunderstorms mainly along the coast and over the coastal waters
during the morning due to weak elevated instability.
Dry, cool high pressure will settle over the area Wednesday
night through Friday with lows in the 40s away from the coast
and highs in the low 70s.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Models initially start out with decent agreement, showing high
pressure moving off the coast Friday night. A Gulf of Mexico system
approaches our area on Saturday. That`s where models disagree on
whether we receive any precipitation from it. We opted to go with a
blend of the models during this time period. By Sunday all of the
models show precipitation over our area and this continues into
Monday. Hence, we trended wetter during this time period.
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Flight restrictions down at least into the MVFR or IFR range
will be the main forecast at both KCHS and KSAV tonight and at
least Wednesday morning, resulting from energy aloft and the
approach and passage of a wave of low pressure riding east-
northeast along a stationary front. Periods of light to moderate
rains and the potential for some heavy rain will occur during
this time. With the passage of a cold front Wednesday afternoon
conditions will improve into the VFR category, but along with
that will be gusty westerly winds that peak at least near 20 or
Extended Aviation Outlook: VFR conditions Wednesday night
through Friday. Unsettled weather may bring flight restrictions
The main concern for tonight is in regards to the possibility of
gale force winds over the Atlantic waters very late tonight and
into Wednesday morning. Latest guidance suggests that the
duration of any such wind gusts would be too limited to not
hoist a Gale Warning. Thus we continue to run with solid Small
Craft Advisories after 2 AM Wednesday on the outer Georgia
waters and starting at 4 AM on all 0-20 nm waters. We certainly
could see the issuance of an advisory in Charleston Harbor, but
for now conditions look to stay just shy late tonight. Seas will
respond to the strengthening winds, climbing from 2-4 ft early,
up as high as 5 or 6 ft within 20 nm and even to 7 ft on the
outer Georgia waters. The coverage of showers will increase as
well, with heavy rains at times after midnight spreading from
south to north, resulting in visibilities under 1 nm at times.
Isolated t-storms will also develop during the overnight period.
Low pressure will pass through the area Wednesday morning after
which high pressure will gradually build across the waters. The
strongest winds and largest seas are expected Wednesday morning
due to the tightest gradient moving through. Cold air advection
will gradually increase later Wednesday and Wednesday night
though low-level winds will have dropped off considerably by
then. We are showing solid Small Craft Advisory conditions
continuing through much of Wednesday.
High pressure will bring tranquil marine conditions Thursday
and Friday. Conditions could start to deteriorate on Saturday as
a system to our south approaches/develops.
Coastal Flooding: Depending upon how quickly winds start to turn
offshore in direction, minor coastal flooding is possible with the
high tide Wednesday morning. A Coastal Flood Advisory is possible for
parts of the South Carolina coast, including downtown
Rainfall Records for 15 October:
MARINE...Small Craft Advisory from 4 AM to 5 PM EDT Wednesday for
Small Craft Advisory from 2 AM to 8 PM EDT Wednesday for
Small Craft Advisory from 4 AM to 8 PM EDT Wednesday for
Area Forecast Discussion
National Weather Service Key West FL
954 PM EDT Tue Oct 15 2019
Mostly clear and dry weather prevails across the Florida Keys on
this mid October evening. Radars detect no significant
precipitation across the service area. Temperatures along the
island chain are slowly dropping through the lower 80s, and winds
on land are from the ESE around 10 mph.
Surface analysis depicts weak high pressure centered off the New
England coast, with a feeble ridge axis extending southwest to the
Florida peninsula and into the central Gulf of Mexico. Aloft,
water vapor imagery shows a dominant deep layered ridge extending
from the western Gulf across South Florida and the Keys to the
Greater Antilles. The 00Z Key West, Miami and Nassau soundings all
reflect the suppressing influence of this ridge, with low
inversions based between 3000 and 4000 feet, dry mid levels, and
below normal PW values ranging from 1.28 to 1.68 inches.
Overnight, expect mostly clear and dry weather to continue, with
only the slightest chance of a shower. Although the sounding
data, current lack of any shower activity on radar, and the lack
of shower activity early Tuesday morning would suggest that rain
chances could probably be zeroed out for the overnight period,
some of the CAM guidance including the HRRR does show scattered
showers developing near the Lower Keys late tonight, and will opt
to leave the existing 10 percent PoPs unchanged. Otherwise expect
overnight lows to drop to between 75 and 80 degrees, with
decreasing winds and clear skies allowing minor radiational
cooling for sheltered interior island locations such as North Big
Pine Key. The existing forecast is on track, and no updates are
planned for this evening.
No watches, warnings or advisories are currently in effect, and
none are anticipated during the next few days. Evening C-MAN and
Weatherflow observations show gentle to moderate ESE breezes
continuing along the Florida Reef Tract, while winds are slightly
lower on the Gulf waters. Short-term guidance remains consistent
in showing winds weakening a few knots and veering to the SE late
tonight, then becoming light southerly on Wednesday as the ridge
axis settles southward near the Keys waters. No significant
changes are planned for the late evening forecast issuance.
VFR conditions will prevail at the EYW and MTH island terminals
overnight and Wednesday, with mostly clear skies and little or no
shower activity in the area, as dry and stable mid levels continue
to suppress convection. Surface winds from the ESE at 5 to 10
knots this evening will veer to the SE and weaken late tonight,
then become SSW around 5 knots on Wednesday afternoon.
Positive water level anomalies continue to run between 1.0 and 1.2
feet above predicted levels at the Key West and Vaca Key tide
gauges. The Blackwater Sound gauge also continues to run above
predicted levels. A Coastal Flood Advisory remains in effect for
the Middle and Upper Keys, while a Coastal Flood Statement remains
in effect for the Lower Keys. This coastal flooding episode has
been ongoing for over three weeks now, and there is nothing to
indicate that it will end anytime soon. Underlying astronomical
tides will decrease slightly during the next several days, but
then will begin building again late next week toward a seasonal
peak on October 29.
FL...Coastal Flood Advisory for FLZ076-077.
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Area Forecast Discussion
National Weather Service Marquette MI
634 PM EDT Tue Oct 15 2019
.SHORT TERM...(This evening through Wednesday)
Issued at 316 PM EDT TUE OCT 15 2019
...Continued rain with gusty conditions developing late tonight...
Vigorous closed mid-level low is pushing ESE through MN today per RAP
analysis, with the associated deepening sfc low centered over south-
central WI as of 18Z. Widespread moderate rain is currently falling
mainly east of a line from Baraga to Iron River, primarily forced by
WAA/Warm frontal Fgen. It`s a cold, gross-feeling rain, and in fact
per radar imagery and forecast soundings the melting level is likely
only 1-3kft AGL. Did have a brief METAR report of snow at LNL
earlier today but primary p-type is expected to remain liquid
through this afternoon. A little thunder also approached the UP
border earlier, but it appears unlikely that any will reach the area
at this point.
As the low continues to deepen it will track ENE across Lake
Michigan to northern Lower Michigan overnight. After a brief lull in
the rainfall this afternoon, a deformation band currently developing
over NW WI will fill in and track across the UP this evening into
tonight. Looking more likely that at least some snow will mix in
over the interior west this evening, but the window will close
quickly as sfc temps are actually expected to warm slightly
This precip will gradually diminish from west to east
after midnight, but will continue into Wednesday primarily over the
upslope-enhanced northcentral UP as well as the east where synoptic
forcing will linger a little longer. Some lake enhancement may also
contribute to drizzle and light rain holding on over the north
central much of the day, as 850mb temperatures cool to -2 to -4C,
over water sfc temps near 10C. In total through Wednesday afternoon,
nearly everyone should see >0.5" of rain, with amounts near 1" over
much of the area excluding the Keweenaw and south-central UP where
lower totals are expected. Rainfall in excess of 1" and perhaps
locally approaching 2" will be possible over the north-central and
east where onshore and upslope enhancement occurs.
The other primary impact of this system will be rapidly
strengthening winds overnight into tomorrow, first out of the NE,
then turning due N late tonight and eventually NNW Wednesday
afternoon as they begin to weaken again following the departure of
the sfc low. Expecting gusts of 25-35 mph from late tonight through
Wednesday afternoon over all but the interior western UP, and
wouldn`t be surprised to see a couple 40 mph reports along the Lake
Superior shores near and east of Marquette tomorrow morning. A
marginal threat of minor beach erosion or minor damage to docks,
etc...is possible as waves are expected to reach nearly 12 feet,
just shy of Lakeshore Flood Advisory criteria. If winds/waves were
to overperform, the headline may be needed.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 437 PM EDT TUE OCT 15 2019
Models suggest that a progressive pattern will prevail with
mid/upper level troughing into the Great Lakes giving way to ridging
toward the end of the week and sw flow early next week as heights
lower across northwest CONUS and the plains. Cold conditions will
moderate with above average temps from Friday into early next
Wednesday night, lake effect rain showers will continue north
cyclonic 25-30 knot 950-900 mb winds and 850 mb temps to around -4C
and inversion heights from 5k-6k ft.
Thursday, some isolated lake effect rain showers will be possible
early north central with with lingering north winds, 850 mb temps
around -5C and inversion heights to 5k ft. With mid level and sfc
ridging building into the area, expect thinning clouds with some
sunshine by afternoon. Highs should still remain in the upper 40s to
Fri, WAA will increase ahead of a mid level shrtwv and sfc trough
moving toward the Upper Mississippi Valley. Although clouds will
increase the WAA will also help temps rebound into the 50s.
Friday night and Saturday, a shortwave moving through the western
Great Lakes should bring another brief round of pcpn into the
region. POPs have increased since models were more consistent with
the forcing and pcpn timing. 700-500 mb fgen is likely to support a
band of rain through Upper Michigan into Saturday afternoon. Some
lighter WAA/isentropic lift pcpn is also possible from late Fri
night into early Saturday.
Sunday, expect dry weather to prevail ahead of the next system.
Mild conditions will continue with highs in the upper 50s to
Mon-Tue, A stronger shortwave and sfc low is expected to develop and
approach the western Great Lakes by late Sunday night into Monday or
Monday night with more substantial rain and strong winds possible.
Although the models have converged toward low development toward a
low path to the west of Upper Michigan, confidence in any details
remains limited low given lingering differences. Colder air moving
in Tuesday could bring lake enhanced/effect rain possibly mixed
with snow as 850 mb temps drop into the -1C to -4C range.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 633 PM EDT TUE OCT 15 2019
IFR conditions at SAW and IWD will continue into tonight with light
rain moving through before conditions slowly improve at both sites
to MVFR, first at IWD. CMX will remain MVFR for most of this
forecast period. North winds will become breezy later tonight with
gusts of 20 to 30 knots, highest at KSAW.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 316 PM EDT TUE OCT 15 2019
NE winds of 20 to 25 knots over western Lake Superior today will
increase to 30 knots tonight across the entire lake. Northerly gales
to 35-40 knots appear likely over the east half of Lake Superior
late tonight into Wed as pres gradient tightens and cold advection
and deeper mixing occur on the backside of the deepening storm
system as it moves over northern Lake Huron. Gale warnings have been
pushed back a few hours for LSZ265-267 and adjacent nearshore zones
from late Tuesday night through much of Wed. A high pressure ridge
will build in from the west Wed night into Thu, with winds subsiding
eventually below 20 knots by Thu. By late Friday into Saturday,
another low across Canada will extend a trough to the south,
allowing southerly winds to gust up to 20 to 30 knots across central
and eastern portions of the lake. Winds will fall back below 20
knots Saturday night.
Gale Warning from 6 AM to 8 PM EDT Wednesday for LSZ251-267.
Gale Warning from 2 AM to 5 PM EDT Wednesday for LSZ248>250-266.
Gale Warning from 2 AM to 2 PM EDT Wednesday for LSZ265.
Gale Warning from 4 AM to 8 PM EDT Wednesday for LMZ221-248-250.