Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/04/18
Area Forecast Discussion
National Weather Service Boise ID
905 PM MDT Wed Oct 3 2018
.DISCUSSION...
Showers and isolated thunderstorms spreading into southern
portions of the forecast area about as expected. Lowered the
chance of precipitation a little over southern Harney and Malheur
Counties through midnight based on limited showers at present and
latest HRRR not generating much precipitation there either.
Otherwise the forecast looks good.
&&
.AVIATION...VFR through much of the night with areas of MVFR in
early morning. Isolated showers will continue to press in from the
south through early Thursday morning becoming widespread by early
afternoon. Cold front pushes into SE Oregon early morning then hits
SW Idaho by early afternoon. Surface winds, west-northwest 5-10kts
increasing to 10-15kts with frontal passage with gusts of 20-25kts.
Winds aloft to 10k feet MSL, northwest 25-30kts.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Friday...Isolated showers and
thunderstorms were starting to develop this afternoon near the
ID/NV border and in southeast Oregon south of Burns and Rome. The
shower activity will expand in coverage with a northeastward
expansion overnight. Any thunderstorms are expected to end by
midnight. The showers will continue through Thursday ahead of an
approaching upper trough and cold front. Snow levels will be at or
above 9000 feet ahead of the front, then fall to around 7000 feet
for a chance of light snow accumulations on the peaks in the West
Central Mountains. Cooler drier air will arrive with the frontal
passage. The front is expected to move through southeast Oregon
late Wednesday night and southwest Idaho Thursday morning. There
is a slight chance of afternoon thunderstorms ahead of the front,
including a portion of southeast Oregon east of Boise and along
the Nevada border. Gusty west-northwest winds will arrive with the
front, especially east of Mountain Home where it will be windy in
the afternoon. The showers will end in southwest Idaho by late
Thursday evening as the upper trough moves to the east and a drier
northwest flow follows, which will persist through most of
Friday. The next approaching system could bring a slight chance of
showers to southeast Oregon by late Friday afternoon.
Temperatures will be around 10 degrees below normal through the
period.
LONG TERM...Friday night through Monday...The cool and unsettled
pattern will continue. The upper level trough which will spread
showers into our Oregon zones Friday afternoon will continue on a
southeastward track Friday night and arrive over our area Saturday
morning. Models are in good agreement through the weekend, but
timing of the trough is a bit slower than yesterday`s runs. The
trough will deepen southward over the Intermountain Region through
the weekend before slowly exiting to the east Sunday night and
Monday. Scattered to numerous showers will spread across our area
Friday night and Saturday morning and continue through Saturday
afternoon, then end across most of the area Saturday night, but
showers will still be possible along the Nevada border and in the
Magic Valley through Sunday morning. Weak high pressure and
northwest flow aloft will keep most of our area dry Sunday afternoon
through Monday. Highs will be 10 to 15 degrees below normal. Lows
will be near normal Saturday and around 5 degrees below normal
Sunday and Monday.
Monday night through Wednesday...A trough deepens over the area
Tuesday, ushering in colder temperatures Wednesday. Though models
differ on the timing and amount, rain and mountain snow showers
are expected to move through the region Tuesday and Wednesday.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...TL
AVIATION.....JC
PREV SHORT TERM...BW
PREV LONG TERM....JT/AL
Area Forecast Discussion
National Weather Service Denver/Boulder CO
921 PM MDT Wed Oct 3 2018
.UPDATE...
Issued at 921 PM MDT Wed Oct 3 2018
Made a few changes to the forecast based on latest observational
trends. Radar and GOES-016/17 imagery show the precipitation
behind the cold front has been much less than originally
anticipated so lowered PoPs a category across the mountains
especially, and also a bit more on the plains. HRRR insists on
redevelopment tonight generally along and south of I-76, so will
keep PoPs in place for later tonight, though confidence is lower
than earlier today that a decent precip shield will develop. There
is synoptic upward motion that spreads over our area tonight and
moisture in the mid-levels remains pretty good tonight. Thus, the
best chance of some light rain continues to be for the eastern
plains. Cloud cover is also expected to be less and delayed until
much later tonight. With reasonably dry low- level air behind the
front, a stratus deck is much less likely as well. Still expect
ample clouds but just not the low stratus variety. Winds have
already decreased most areas as the pressure gradient has relaxed
after the initial strong push from the northeast. Winds and
overnight lows look on track, and it will be a cool night with
temps in the upper 30s to mid 40s across the plains, and similar
temps in the mountains as the cold air is rather shallow across
the plains, latest Platteville profiler data indicates the cold
air extends to about 9,000 feet across the east slopes.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 234 PM MDT Wed Oct 3 2018
Radars to the north and northeast are showing a decent cold front
moving south at about 35 knots. It is into southern Wyoming at
present. You can see it on the visible satellite pictures too.
Temperatures are about 30 F immediately behind it. Wind speeds
behind the front are generally 20-35 knots. Area radar pictures
are showing some showers developing and moving into the mountains
from the west. Models keep southwesterly flow aloft at about 90
knots at jet level tonight well into Thursday. One piece of the
developing mean trough to our west moves across the CWA on
Thursday. The QG Omega fields show a decent couplet of synoptic
scale energy to move across Colorado tonight and Thursday. The
upward motion tonight/Thursday morning is somewhat strong. Models
show decent moisture over the CWA this evening into Thursday
morning. Moisture decreases Thursday afternoon. The QPF fields
have limited measurable precipitation for a good portion of the
CWA from early evening into Thursday morning. There is fairly
decent CAPE progged over the mountains overnight into Thursday.
With the synoptic scale energy, upslope and available moisture,
the current 30-70% pops look good. For temperatures, Thursday`s
highs are some 7-17 C cooler then this afternoon`s highs.
.LONG TERM...(Thursday night through Wednesday)
Issued at 234 PM MDT Wed Oct 3 2018
For Thursday night into Friday, a trough will be passing over the
region with upper level flow turning more zonal behind it. Will keep
some light pops over the eastern plains into late Thursday with the
continued QG ascent and lift provided by the upper jet. Increasing
subsidence behind the trough will help to clear out precipitation
through the morning hours on Friday. By Friday morning the next
upper level disturbance will be over Utah, moving down from the NW.
By the afternoon a cold front will drop out of the North as the
upper trough is pushing into NW Colorado and the northern mountains.
700mb temperatures will begin to drop behind the front bringing
increased chances of rain and snow to the northern mountain zones 31
and 33 Friday night into Saturday. The forcing will push SE across
the plains increasing rain showers through the morning hours on
Saturday. Freezing levels will drop into the 9 to 10,000 ft range
which will bring snow over the higher elevations and mountain passes
and a rain and snow mixtures to the higher foothills by early
Saturday. Any snow that will fall will have a hard time sticking
with highs remaining above freezing with temperatures in the 50s on
the plains and upper 30s to lower 40s in the mountains.
Precipitation will push out of the area by late Saturday morning
with increasing QG subsidence behind the trough.
The next upper level feature will be over the Great Basin by
Saturday afternoon. This is where the models start to diverge. As
the trough starts to push into the four corners region Saturday into
Sunday the GFS closes off over Utah with the EC slightly further
South into AZ. Even with the disparity in model consensus the system
over the region Sunday into Monday looks to be the best chance for
accumulating snow in the mountains. There will be good lift with
this system with the upper jet and moderate QG values. Models show a
surface low deepening over the eastern plains Sunday afternoon that
will help to increase ESE upslope for the higher foothills and areas
east of the divide. This combined with a northerly push late Sunday
will help to increase snow chances for the northern and central
mountains West of the divide. Models show snow levels decreasing
through Monday into the 8 to 9,000 ft range. Currently, the
mountains could see 3 to 6 inches from Sunday afternoon/evening
through Monday. The plains will continue to see rain with models
showing 700 mb temperatures only in the -1 to 2 C range and that is
just the GFS, the EC is warmer in the mid levels. Temperatures will
still get colder than normal with highs in the upper 40s to low 50s
monday and Tuesday.
The trough train continues into mid week with another possibly
disturbance Thursday/Friday with mild temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 921 PM MDT Wed Oct 3 2018
Confidence is increasing that stratus should not impact the
terminals overnight tonight. While the cold front has moved across
the terminals, upstream observations do not support stratus
formation and GOES 16/17 do not show stratus within several 100
miles of the front. Have hedged bets in the TAF with just barely
MVFR conditions but would not be surprised if it stayed VFR
throughout tonight. Winds have already decreased as expected
behind the front and will gradually turn more east throughout
tonight, and dropping to 8-13 kts or so at DEN and APA. BJC should
remain less than 10 kts out of the north generally. Weak,
isolated showers have developed behind the front but coverage and
intensity is not enough to include in the TAFs. Instead VCSH
should suffice tonight. After mid-morning winds should come
around to southeast, then south to south- southwest by mid to
late afternoon. Winds could gust to over 20 kts at APA and DEN
this afternoon before weakening again this evening.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Schlatter
SHORT TERM...RJK
LONG TERM...Bowen
AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Lincoln IL
1044 PM CDT Wed Oct 3 2018
.UPDATE...
Issued at 830 PM CDT Wed Oct 3 2018
The latest surface analysis depicts a strong cold front over east
central Iowa early this evening starting to surge east and
southeast with 3 hourly pressure rises from 7 to 9 mb across the
Dakotas where 50-55 mph wind gusts were observed. The strong area
of low pressure along the front has surged north to Lake Superior
this evening and will continue to move well to our north tonight.
Scattered convection has developed along the boundary with the
latest HRRR model bringing the bulk of the convection into our
west and northwest counties after 10 pm. 00z ILX sounding continues
to indicate poor mid level (700-500 mb) lapse rates which may
keep the coverage of any strong storms to a minimum ahead of the
cold front. Instability, at least surface based, should continue
to diminish this evening but strong wind fields, 0-6km bulk shear
of 38 kts, will continue to provide support for isolated strong
wind gusts with some of the more intense updrafts along the cold
front.
The current forecast has a good handle on the trends this evening
with respect to timing of the convection into our area and with
temperatures, so other than some minor adjustments to the hourly
temperatures and winds this evening, no significant changes were
made that would require a ZFP update at this time.
&&
.SHORT TERM...(This evening through Thursday)
ISSUED AT 315 PM CDT Wed Oct 3 2018
19z/2pm surface analysis shows a strong cold front extending from
eastern Minnesota to northern Nebraska. An unseasonably warm/humid
airmass characterized by temperatures well into the 80s to around
90 degrees prevails ahead of the front, while readings have
plunged into the 50s behind the boundary across the Dakotas.
Despite the impressive thermal gradient, most of the convection
associated with this feature is focused across Minnesota/Wisconsin
immediately ahead of a short-wave trough tracking along the
US/Canada border. Further south along the front, a capped airmass
has prevented convective development thus far. All CAMs are
showing scattered showers and thunderstorms developing along the
trailing cold front by early this evening, with the activity
pushing into the Illinois River Valley between 8pm and 10pm...then
reaching the I-55 corridor by around midnight. Given current
trends and latest HRRR/NAM, have reduced PoPs into the high chance
to likely category. The activity will push further E/SE after
midnight, eventually reaching the I-70 corridor by around 3am.
While SPC continues to highlight locations along/northwest of a
Rantoul to Springfield line for a Marginal Risk for severe, think
decreasing instability and a lack of strong deep-layer shear will
prevent severe development. Once the front passes, breezy and
much cooler conditions will spill into the area from the northwest
after midnight. Overnight lows will range from around 50 degrees
in Galesburg to the lower 70s south of I-70. A few showers will
linger across the E/SE KILX CWA into Thursday morning: however,
most spots will remain dry as the front settles southward into the
Ohio River Valley. High temperatures will be considerably cooler
than today...ranging from the lower 60s in the Illinois River
Valley to the upper 70s far southeast around Lawrenceville.
.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 315 PM CDT Wed Oct 3 2018
The extended forecast will be dominated by warm and unsettled
weather as the prevailing baroclinic zone wavers across the
Midwest through at least the middle of next week. This will
result in periodic rain chances and plenty of ups and downs in the
temperature.
The Ohio River Valley frontal boundary will lift back northward
into central Illinois...triggering another round of showers and
thunderstorms late Thursday night into Friday morning. Rain
chances will diminish from south to north across the area by
Friday afternoon as the front lifts to the I-80 corridor. Due to a
return to warm/southerly winds and a lull in the precip chances,
afternoon high temperatures will once again surge well into the
80s across at least the southern two-thirds of the CWA.
Another cold front will begin to approach from the west late
Friday night into Saturday, bringing another uptick in rain
chances at that time. This boundary will have difficulty passing
through the region as a strong upper-level ridge of high pressure
builds over the southeastern CONUS. The ridge will essentially
act as a blocking mechanism, thus keeping the frontal boundary
from exiting the region. As a result, warm and showery weather
will persist for both Saturday and Sunday.
After that, the ridge will become even stronger early next
week...shifting the front back to the N/NW and placing central
Illinois solidly in the warm sector. Am therefore expecting very
warm and dry conditions on Monday...with only chance PoPs
returning to the picture by Tuesday. High temperatures both days
will reach the middle to upper 80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1040 PM CDT Wed Oct 3 2018
Outside any convection during the early morning hours, we are
looking for mostly VFR conditions across the forecast area.
Cold front over eastern Iowa continues to make steady progress
to the east with scattered showers and storms along the boundary.
A few of the storms, if they can get into a TAF site, will be
capable of producing wind gusts of 40-45 kts, but based on reports
to our west, those type of wind gusts will be few and far between.
The front should push east of the forecast area by 12z. There
still is the threat for a brief period of MVFR cigs immediately
behind the cold front Thursday morning so will continue to carry
scattered to broken cigs around 3000 feet just after FROPA.
Surface winds will continue from a south to southwest direction
ahead of the cold front with speeds in the 15 to 20 kt range with
a few gusts up to 30 kts at times, especially in and near any
convection. Look for winds to shift into the northwest just after
FROPA in the 08z to 12z time frame across our forecast area. Winds
on Thursday will then turn more into the north to northeast by
afternoon with speeds in the 12 to 17 kt range with a few gusts up
to 23 kts at times before diminishing from a mostly easterly
direction by 00z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Smith
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Smith
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
927 PM CDT Wed Oct 3 2018
.UPDATE...
927 PM CDT
Generally only minor tweaks made to going forecast this evening,
though have adjusted gridded pops a few times to sharpen up the
leading and trailing edges of precip and add more detail to timing
of greatest storm threat.
02Z surface analysis depicts a sharp cold front stretching from
low pressure over Ontario/northern Lake Superior, southwest across
Wisconsin and into eastern Iowa. Broad, warm and breezy warm
sector air mass was in place ahead of the front. High-res guidance
had been more bullish earlier on convection developing within a
pre-frontal convergence zone ahead of the front, though trends
have been for mainly a few elevated showers in warm advection
atop slightly decoupled boundary layer this evening. Most
organized convection is immediately along/ahead of the cold front
to our west, and while scattered showers and storms will likely
increase in advance, the storms associated with the surface
frontal zone are expected to be the main show. Rough timing would
suggest the greatest threat for storms into the Rockford area by
midnight, Chicago by about 1 am, and northwest indiana after that.
Storms will end fairly quickly with the passage of the front
during the pre-dawn hours.
Despite unfavorable seasonal and diurnal timing, anomalously moist
and mild air mass and very strong wind fields will present the
potential for isolated severe weather with the frontal convective
line. Evening upper air analysis indicated 40-50 kt winds in the
925-850 mb layer, and there have been a few 45 kt gusts (52 mph)
noted in Iowa as this line passes. Areas along/north of the I-80
corridor remain in an SPC slight risk overnight primarily for the
damaging wind potential, though strong low-level speed shear will
present a non-zero isolated tornado threat as well.
Winds remain gusty behind the front, with temps dropping into the
50s by morning.
Ratzer
&&
.SHORT TERM...
225 PM CDT
Through Thursday...
Focus in the near term is with an approaching cold front,
specifically gusty winds ahead of the front and convective chances
late today and tonight near the front. Early this afternoon, low
pressure is analyzed over west central Minnesota with a cold front
trailing south-southwest across eastern South Dakota into
Nebraska. Tight pressure gradient is in place ahead of the front
with a broad area of 3-4 mb/3 hr pressure falls which are
contributing to gusty winds across the region. Forecast soundings
from the RAP and NAM support low to mid 30 kt gusts continuing
into early this evening, and top of the channel winds in excess
of 40 kt suggest a few sporadic higher gusts near wind advisory
criteria (39kt/45mph) are possible. Winds will likely remain
gusty through the overnight hours, though should taper some in
magnitude after sunset as mixing becomes less efficient.
Models suggest that convective initiation will occur ahead of the
approaching cold front over portions of Iowa this evening then
thunderstorms will shift east across Illinois and Indiana late
this evening and overnight. Unseasonably warm and moist conditions
this afternoon are contributing to a pocket of moderately
unstable air with MLCAPE of around 1500 J/kg currently over the
region. RAP suggests that instability will further increase to
around 2000 J/kg immediately ahead of the front late this
afternoon, but should gradually diminish as the front moves across
the local area overnight. Moderately strong instability and
strong low to mid level winds (900-700mb winds average in excess
of 50 kt at times) will support a low end severe threat with
storms, especially west of the I-39 corridor, but that threat
along with overall storm coverage should diminish with time as
storms move east across the local CWA.
Cold front will begin to sweep across the CWA late this evening
and overnight turning winds northwest in its wake and ending the
chance for thunderstorms. Guidance has trended a little slower
with timing of the frontal passage and expect passage around
midnight to 100 AM CDT in the Rockford area and 200-400 AM CDT for
the Chicago metro area. Winds will remain breezy behind the front
well into the day Thursday, but should very gradually diminish in
magnitude as high pressure builds towards the region. Temperatures
are expected to top out 20-25F cooler Thursday with highs only in
the 50s and 60s.
Deubelbeiss
&&
.LONG TERM...
302 PM CDT
Thursday night through Wednesday...
Active period of weather is expected for the long term forecast
period.
Then next round of thunderstorms is expected to move into the area
Thursday night into Friday as a warm front surges north across the
area while deepening low pressure lifts northeast across central
Iowa and through Wisconsin. Warm sector air will be in place by mid-
day Friday. Scattered showers and thunderstorms will likely be
ongoing by the morning commute Friday morning. Coverage and
intensity will likely increase through the evening, focusing along
the sfc low and associated frontal system. Strong low level forcing
associated with frontal convergence and a 30-50 kt low-level jet
aligned with relatively high instability will combine to bring a
severe threat, which is currently looking to be focused over the
nwrn portions of the CWA in the evening. Into the overnight hours,
the severe threat should diminish diurnally, but a heavy rainfall
threat will persist overnight as unseasonably high pwats in excess
of 1.75 inches will be in place, pooling along the frontal system.
The latest WPC Day-3 Excessive Rainfall Outlook in highlighting
locations north and west of the I-55 corridor in a Slight Risk for
excessive rainfall. Currently feel that much of the guidance could
be a little conservative in the QPF with the system and that the nwrn
portions of the CWA could see on the order of 2 to 3 inches storm
total rainfall for the period from Friday afternoon through
Saturday. With portions of the Rock and Pecatonica Rivers already
in flood from previous upstream rainfall, expect that additional
flooding of area rivers will be likely.
High pressure parked over the sern CONUS will limit the southward
push of the cold front, likely becoming quasi-stationary across
cntrl IL/IN through the day on Sunday. With the boundary parked
just south of the CWA, pcpn chances will continue through the day.
Another low is expected to develop over the Western Plains by
Monday, with another round of strong storms likely with the next
frontal passage. Timing with the second round of storms may be a
little more uncertainty and will be dependent on the timing of the
progression of the system. Latest guidance suggests Thursday or
Thursday night, but anticipate that timing will become a bit more
certain with time.
&&
.AVIATION...
For the 00Z TAFs...
658 pm...Several forecast concerns this period including a period
of scattered thunderstorms late this evening into the early
morning hours...strong gusty southwest winds shifting northwest
with a cold front overnight and then shifting northeast Thursday
morning.
A few showers have developed near ord and isolated showers will
be possible this evening. However...more organized showers and
scattered thunderstorms are expected along/ahead of a cold front.
Adjusted timing slightly and also increased the tempo to 3 hours
for the possibility of two lines of convection. Some lingering
showers may persist behind the front...but as the colder air
rushes into the moist air ahead of the front...a brief period of
low mvfr or ifr cigs are possible. While prevailing winds are
likely to remain southwesterly during the precip...erratic/gusty
winds are possible with the strongest storms.
Winds will shift northwest behind the cold front and forecast
soundings suggest gusts into the mid 20 kt range. Winds will then
slowly turn northerly by sunrise and are expected to shift to the
north/northeast by mid morning Thursday and remain northeasterly
for the remainder of the period.
There is another chance for showers and isolated thunderstorms
early Friday morning...just after the end of the current 30 hour
ord/mdw tafs...so no mention for now. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...IL nearshore waters until 10 AM Friday.
Small Craft Advisory...IN nearshore waters until 4 AM Friday.
&&
$$
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Area Forecast Discussion
National Weather Service Melbourne FL
910 PM EDT Wed Oct 3 2018
.UPDATE...
Tonight...A weak low level inverted trough will approach southern
sections late. Breezy low level east/northeast winds ahead of this
feature were already setting up convergence lines over the Atlantic
and increasing marine shower coverage in the south. Higher moisture
associated with the inverted trough will then arrive there late.
Therefore, have increased PoPs along the Treasure Coast to 40-50%.
The HRRR model shows some lightning over the southern coastal waters
towards 12z, but won`t introduce any thunder to the south coast yet.
Otherwise, no significant changes with lower coverage of showers
moving ashore northward. Low level winds around 15 knots should
push a few showers well inland, especially in the south.
&&
.AVIATION...Conditions will be VFR for most of the area, except
brief MVFR can be expected at coastal terminals, especially KMLB
southward as showers move ashore overnight and into Thu morning.
&&
.MARINE...
Tonight-Thursday...Recent buoy reports show seas 4-5 feet nearshore,
but 41009 has been 6-7 feet. Even though conditions nearshore look
marginal for an Advisory for Hazardous Seas, will not make any
changes because 1) wave guidance shows seas slowly increasing
overnight and into Thu 2) winds at 41009 have been around 15 knots
so the combination of wind wave/swell will produce rough conditions
for small craft operation and 3) showers will produce occasional
wind gusts 20-25 knots.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory for hazardous seas from 10 PM this evening
to 4 AM EDT Friday for Sebastian Inlet to Jupiter Inlet 0-
20 nm-Volusia-Brevard County Line to Sebastian Inlet 0-20
nm.
Small Craft Advisory for hazardous seas until 4 AM EDT Friday
for Flagler Beach to Volusia-Brevard County Line 20-60 nm-
Sebastian Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard
County Line to Sebastian Inlet 20-60 nm.
&&
$$
Forecasts...Lascody
Impact WX/Radar...Sedlock/Combs
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
717 PM CDT Wed Oct 3 2018
.SHORT TERM...(This evening through Thursday)
Issued at 345 PM CDT Wed Oct 3 2018
A powerful early Fall cold front was moving rapidly to the east
across western Minnesota this afternoon. Ahead of this front, dew
points rose into the upper 60s, to lower 70s which is very
anomalous for early October. PWATs are either in record territory,
or near it with readings around 1.6". The warm sector was
producing severe thunderstorms in northern Wisconsin this
afternoon, with a mixture of rain/snow in northwest Minnesota
where afternoon temperatures were in the 30s.
You will notice the cold frontal passage this evening as winds
shift to the northwest and begin to gusts over 40 to 50 mph. Wind
gusts over 60 mph were occurring in eastern South Dakota where the
front moved through earlier this afternoon. Severe weather will
be confined to west central Wisconsin where the best instability
and wind shear exists early. Most of the active storms will have
moved out of west central Wisconsin by 7 PM. The main weather
element this evening will be the strong winds ushering in the
coldest air of the season. By morning, temperatures will have
fallen into the 30s, with wind chill values in the 20s. Skies will
be sunny in the morning, but it will be short lived as the next
system rapidly moves to the northeast across the Rockies, and into
the Northern Plains by the afternoon. Scattered showers will be
likely in far western Minnesota by the mid/late afternoon, with
skies becoming cloudy elsewhere.
.LONG TERM...(Thursday night through Wednesday)
Issued at 355 PM CDT Wed Oct 3 2018
Very little changes in the extended period with the active weather
pattern continuing.
Thursday night and early Friday will be wet as the next in the
series of short waves move across the Upper Midwest. Saturday
looks to be the driest, but Sunday will have another good chance
of widespread precipitation.
Overall, the mean upper level flow will remain from the west
early, then back to the southwest as a deep trough begins to dig
across the western CONUS this weekend. Several waves of energy
will begin to eject out of this deepening trough out west and lead
to periods of precipitation. Timing, and areal extent of the
precipitation remains the forecast concern. However, based on the
consistency of the models and the deep elongated trough out west,
the Upper Midwest will likely see bouts of heavy rainfall, leading
to flooding concerns over the weekend, and into next week.
Most of southern Minnesota and western Wisconsin will stay on the
warm side of the synoptic scale thermal ridge centered over the
Northern Plains. However, any deviation to this thermal ridge or a
much more aggressive short wave moving further to the southeast,
will lead to a colder scenario and possibly a mixture of
rain/snow. This is even more notable in western Minnesota where
this thermal gradient will likely be closer. Otherwise, with the
precipitation chances high and likely a broad area of cloud cover,
temperatures will likely average below normal through early next
week. The longer range models still depict a colder pattern, at
least for the northern Rockies, and into the Northern Plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 717 PM CDT Wed Oct 3 2018
Squall line will clear EAU by 1z and after that the main concerns
are the gusty northwest winds behind the cold front and how long
the MVFR cigs will stick around. Satellite and obs show fairly
extensive stratus back into the eastern Dakotas. As a result,
delayed improvements to VFR closer to what the NAM soundings and
HREF probs show. We`ll see mainly clear skies in the morning, but
in the afternoon mid level clouds will increase as isentropic lift
increases ahead of the next system. We should start seeing rain
move into western MN around 21z, with rain reaching AXN/RWF by the
end of the period.
KMSP...NAM soundings and HREF probs would say MVFR cigs lingering
to as late as 10z, so may need to delay improvement to VFR
further. Looking at dry low levels on forecast soundings, rain
reaching MSP as early as the 18z HRRR has it (22z) is a bit
unlikely. Like the idea of the GFS/NAM that it stays out until
after 00z Thu.
/OUTLOOK FOR KMSP/
Fri...MVFR/IFR. Chc -SHRA. Wind SE 5-10 kts.
Sat...MVFR cigs. Wind N 5-10 kts.
Sun...Mainly MVFR. Chc aftn -SHRA. Wind E 10G20 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Wind Advisory until midnight CDT tonight for MNZ067-075>078-
083>085-092-093.
Wind Advisory until 9 PM CDT this evening for MNZ054-056-064-065-
073-074-082-091.
&&
$$
SHORT TERM...JLT
LONG TERM...JLT
AVIATION...MPG