Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/14/24
Area Forecast Discussion
National Weather Service Cheyenne WY
535 PM MDT Sat Apr 13 2024
.KEY MESSAGES...
- Above normal temperatures expected again Sunday.
- Elevated to locally critical fire weather conditions both
Saturday and Sunday afternoons. Red Flag Warnings are in
effect for this afternoon.
- The next storm system will arrive Monday afternoon and bring
showers and thunderstorms to the valleys and snow to the
mountains. Snow may also mix in for the higher valleys and
plains of Southeast Wyoming Tuesday morning.
&&
.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 245 PM MDT Sat Apr 13 2024
Surface trough from this morning has pushed off to the east and
southeast this afternoon. Still a band of fairly thick clouds
over the southern Panhandle and along the I-80 corridor to
Cheyenne in southeast Wyoming. Seeing some virga here at the
office as radar is painting some echoes under that band of
clouds. Thinking most of the returns are not reaching the ground
as surface humidity is still quite low. 1PM humidity over the
Panhandle in the mid teens and around Cheyenne here...mid to
upper teens percent are fairly common. HRRR and RAP simulated
radar continues to advertise a slight chance for showers across
the southeast CWA this afternoon...so will keep slight chance
PoPs (15 to 20 percent) going through 00Z.
To the north of this cloud band...skies are mostly sunny and the
atmosphere is pretty well mixed. Getting fairly widespread
humidity below 15 percent with wind gusts 30-35 mph in the two
fire weather zones we have a Red Flag Warning in effect for.
Since they are hitting quite consistently...will keep the Red
Flag Warnings going through 7PM.
Off to the west...The closed low off the coast of central
California as yet to make it onshore. Occluded low is just
making it into central California this afternoon. This low
tracks into central and southern California by Sunday morning
and then into southern Nevada by Sunday afternoon. Upper ridge
will be over our CWA for Sunday...with fairly light winds for
most areas. The exception may be out across western Carbon
County where the GFS is advertising 700/750mb wins 30-35kts.
Given the weaker winds for areas east...decided to cancel the
Fire Weather Watches for central and eastern Laramie Counties
for Sunday.
We do see a low level southeasterly jet setting up across the
Panhandle and areas east of the Laramie Range for Sunday night
into Monday as 800/850mb winds increase to 35-45kts Sunday night
into Monday. This could bring in some low level moisture from
the Gulf of Mexico and 850 humidity rises to near 65-70 percent
across the Panhandle.
By Monday late morning...closed low looks to be situated over
east central Utah with diffluent upper level flow over the
Cheyenne CWA. Broad 700mb low near the Colorado/Wyoming state
line and slowly shifts northeast as upper energy moves into
northern Colorado and central Wyoming. ECMWF and GFS showing
fairly widespread QPF over the CWA by Monday afternoon and
evening. SPC continues a Marginal Risk area for the Nebraska
Panhandle Monday afternoon and evening.
Finally...we need to be on the lookout for a high wind event for
the I-80 Corridor in southeast Wyoming Monday night into
Tuesday. GFS advertising 50-60kts 700/750mb winds over the
Summit in central Laramie County behind the front when it moves
through. Could see high wind headlines during this time for at
least these two zones.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Issued at 245 PM MDT Sat Apr 13 2024
Looking at unsettled and cooler weather for the long term forecast
as an active synoptic pattern brings multiple rounds of
precipitation to the region.
The system responsible for Monday`s myriad of weather will
become more organized as it pushes east on Tuesday. Both the
surface low and 500 mb low will strengthen, becoming vertically
stacked over the central Kansas/Nebraska border. Placement of
the low will allow this system to tap into moisture from the
Gulf of Mexico. With this system being east of the CWA by the
time it really gets organized, the region will mainly be
impacted by wrap around moisture as well as strong, northerly
winds on the backside of the low. 700 mb temperatures will still
be above zero, so precipitation on Tuesday will likely still be
rain. Non-zero CAPE values will exist in the Nebraska panhandle
Tuesday afternoon, so some rumbles of thunder could be
possible. The high terrain will likely be the only areas to see
any snow falling during the day. As previously mentioned,
blustery conditions can also be expected, especially for areas
east of the Laramie Range where 800 mb winds could max out at 55
kts. This could lead to another high wind event with gusts over
60 MPH possible. Precipitation will dissipate by Tuesday
evening, but winds will remain blustery.
As soon as the surface low pushes east into the Great Lakes Region,
a broad trough will drop down from Canada over most of northern
CONUS. This will lead to continued windy conditions over much
of the CWA as pressure gradients tighten ahead of a cold front.
Winds will be westerly, so the typical wind prone areas will
feel the effects. In-house guidance is even picking up on an
elevated to marginal high wind event for some of the wind
prones. Wednesday afternoon, the cold front pushes through
bringing much colder temperatures and another chance for
precipitation. By Wednesday night, 700 mb temperatures could be
as cold as -10C, and potentially even colder. This could lead
to snow and possibly some light accumulations across the area
Wednesday night.
The frontal boundary will linger just to the south of the CWA
through the end of the week. Because of this, enough moisture will
be around in the mid-levels as well as a broad 250 mb jet to spark
some precipitation across the area. Amounts and exactly who sees
precipitation are still yet to be determined as this is still quite
a ways out. There is, however, more confidence in that temperatures
will be much colder as the cold air lingers just behind the front.
As a result, did lower high temperatures below NBM guidance.
Temperatures will likely stay below average through at least the end
of the work week.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 535 PM MDT Sat Apr 13 2024
Upper level ridge axis will remain over the Front Range through
Sunday with relatively light winds and intervals of cloud cover each
afternoon.
HAZARDS/WEATHER TRENDS: VFR conditions will continue tonight through
Sunday afternoon with some FEW-SCT mid to high clouds. Westerly
winds gusting up to 25 knots will subside shortly after sunset (02z)
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None after 7 PM.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...SF
AVIATION...TJT
Area Forecast Discussion
National Weather Service Dodge City KS
1023 PM CDT Sat Apr 13 2024
...Updated Aviation...
.KEY MESSAGES...
- A warm day on Sunday with near record high potential for Dodge
City.
- Severe event on Monday is still on track to be more of an
evening/overnight event.
- Potential high wind warning criteria winds on Tuesday.
&&
.SHORT TERM /THROUGH MONDAY/...
Issued at 200 PM CDT Sat Apr 13 2024
18Z obs and RAP upper air analysis shows a large 538 dm closed
low centered of the northern California coast with a mainly
zonal subtropical jet in the central and southern plains and a
weak shortwave moving through northwest Kansas. At the surface
1006 mb low is located in southwest Nebraska and a trough
extends through western Kansas into Oklahoma which is leading
to southwest winds and relative humidity values in the 10-20%
range.
Throughout tonight the surface low will slowly move eastward
into southeast Nebraska but with little upper air divergence
with the short wave we shouldn`t see much deepening of the low.
The trough/windshift line should bisect southwest Kansas from
Hays to Liberal by sunrise and winds in the boundary layer
should switch to the north. 850 mb temperatures will stay warm
through the night at 20-22 (C) so lows will only fall into the
upper 40s to lower 50s.
On Sunday as the upper low in the Pacific coast moves ashore the
jet stream ahead of it should ridge in the central plains
leading to mainly sunny skies through the day. Winds in the
morning will start east to northeast and then switch to the
southeast by late in the day. 850 mb temperature trends in the
short term models suggest we shouldn`t see much cooling and by
late in the day with diurnal heating we should see widespread
24-26 (C) temperatures. With relative humidity values falling to
around 10% we should have enough efficient heating to overcome
the light east winds and highs will reach into the upper 80s to
lower 90s. The record for Dodge City is 92 and we could
certainly make a run at tying that record.
Sunday night the approaching storm system will be located just
west of the four corners region and the jet streak will be
entering into southern Colorado. Winds in the boundary layer
will start to turn southeasterly and gulf moisture will stream
into central Oklahoma and Kansas through the night which could
lead to a deck of stratus clouds moving in by morning. The
highest moisture in the east will keep the temperatures up
through the night with lows in the upper 50s to lower 60s. Out
west with lesser moisture temperatures will cool into the upper
40s to lower 50s.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Issued at 216 PM CDT Sat Apr 13 2024
Latest medium range ensembles are continuing to show a powerful
upper level storm system affecting the central plains from
Monday evening through Tuesday afternoon. The upper level low
track has been staying consistently through southern Colorado
into northwest Kansas with the upper level jet extending from
central New Mexico to northeast Kansas.
Both EPS and GEFS ensembles agree with the slower progression of
the upper low most of the prime severe weather setup will likely
be after 7pm in southwest Kansas and perhaps as late as 10 pm
before initiation of convection starts. Through the day as the
surface low in northeast Colorado deepens to 992 mb a dryline
will extend roughly along the highway 283 corridor and with
strong southwest winds and humidity values falling below 15% we
will likely (>90%) have red flag criteria from highway 283 to
the Colorado border for Monday afternoon. With the nose of the
jet moving into northwest Kansas by 00Z the surface low will be
in northwest Kansas and the eastward progression of the dryline
will make it to the highway 183 corridor.
After 7pm is when the low level jet increases to 35-50 kts from
highway 283 on east and we should see southeast winds at the
surface bring the moisture back to potentially as far west as
highway 83 as the deterministic Euro and EPS have both been
trending towards. At around 10pm the strongest nose of the 500
mb jet enters into southwest Kansas and this is where the
strongest lift should arrive along the dryline. Hodograph
soundings show good veering with height which would support
large to giant hail with any storm development and the storm
motion being almost parallel to the dryline would suggest quick
upscale growth and the formation of a squall line roughly along
and east of highway 283. Hail, wind, and tornadoes are going to
be in play with these storms.
Tuesday is showing the threat of strong surface winds and
blowing dust. As the surface to 500 mb low moves into southern
Nebraska EPS MSLP of the low falls to 989 mb and we should have
at least a 10 mb pressure gradient in southwest Kansas. EPS and
GEFS do have some wind gusts approaching 60 mph along the
Colorado border and the NBMv4.1 guidance loaded sustained 35 kt
winds with gusts to 50 kts. This is fairly aggressive for the
nationally blended model to put in winds that high and I see no
reason at this time to doubt it.
&&
.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1023 PM CDT Sat Apr 13 2024
Excellent flying weather will continue through this TAF cycle,
with VFR/SKC and light winds, less than 12 kts, variable in
direction.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Monday afternoon through Monday
evening for KSZ030-043>045-061>064-074>078-084>088.
&&
$$
SHORT TERM...Tatro
LONG TERM...Tatro
AVIATION...Turner
Area Forecast Discussion
National Weather Service Grand Rapids MI
941 PM EDT Sat Apr 13 2024
.KEY MESSAGES...
- Most Stay Dry, Isolated Showers and Storms Tonight
- Beautiful Weather to End the Weekend
- Mild Temperatures to Begin the Week
- Showers and Storms Tuesday into Thursday
- Cooler with a Chance for Showers Late Week into the Weekend
&&
.UPDATE...
Issued at 940 PM EDT Sat Apr 13 2024
Current regional radar shows best concentration of showers well to
our north in an arc from wrn Lk Superior to nrn Lake Huron where
the upper jet is located. However there appears to be a band of
ACCAS clouds and newer radar echoes developing over WI on the
leading edge of the incoming mid level theta-e advection.
Despite our currently dry low levels, will maintain the 20-40 pct
pops for showers/tstms overnight as respectable moisture and
instability in the mid levels shifts our way from the west. The
upstream 700-500mb lapse rates are near 9C and our H8 Lifted
index falls to -3C after 06Z as a westerly LLJ strengthens to
50-55 kts. RAP MUCapes near 800 J/KG are progged late tonight with
PWATs jumping from 0.4 to 0.8.
All of these ingredients certainly support keeping the risk of
scattered to isolated late-night convection in the fcst.
&&
.DISCUSSION...
Issued at 303 PM EDT Sat Apr 13 2024
- Most Stay Dry, Isolated Showers and Storms Tonight
Tonight a shortwave trough and associated positive vorticiy
advection pass mainly north of the area late tonight. There will
be plenty of low level lift with the low level jet and warm air
advection, but there is a question as to if there is enough
moisture to pop off a few isolated showers and thunderstorms.
Looking at soundings there should be enough lift to overcome any
CIN, but overall moisture is lacking except toward Gaylord`s area.
The best window of time for showers and storms to occur will be
between 11 PM and 5 AM, afterwards we lose our main sources of
lift and drier air advects into the area aloft.
- Beautiful Weather to End the Weekend
Sunday a weak front will move through the area during the morning
and afternoon with southwest winds shifting to the northwest. With
the front expect some cloud cover, otherwise mostly sunny skies
are expected behind the front. Temperatures tomorrow will be a
little warmer than today with highs getting into the 70s across
most inland areas with upper 50s and 60s closer to the lake. Clear
skies continue into Sunday night with lows in the 40s for most
and in the mid to upper 30s along and north of the US 10 corridor.
- Mild Temperatures to Begin the Week
A negatively tilted upper level ridge will build over the region
late Sunday into Tuesday. This ridge will allow for high pressure
at the surface and mild springtime temperatures. Expect Max temps
on Monday and Tuesday to be around 10 degrees above normal, in the
upper 60s to low 70s.
- Showers and Storms Tuesday into Thursday
The ridge and and mild weather will be short lived as a strong upper
level low will be moving through the great plains and through the
mid west Tuesday through Thursday. Models continue to be in fair
agreement on the placement of the upper level lows and the
corresponding low level pattern. The system at this time seems
fairly barotropic with a decent gradient along with it. There
seems to be decent 500 mb vorticity with mid level moisture that
should cause some overrunning Tuesday. NAEFS PWATS are upwards of
1.25 inches and are +3 anomalous Tuesday evening into Wednesday.
So there remains a good chance for showers Tuesday
The low is still on track to move through late Tuesday night into
Wednesday. This cold front should correspond with a strong low
level jet. A decent amount of instability remains likely. Given
the potential for storm organization strong winds and hail are
possible.
The system looks to become an open wave with more zonal flow into
Thursday with a chance for lingering showers.
- Cooler with a Chance for Showers Late Week into the Weekend
Cold air advection will be the main story behind the front as
850mb temps by daytime Friday will be below zero. These will
continue to drop into the weekend. Maximum temperatures could be
around 10 degrees below normal. Overnight lows, especially with
dry air aloft and subsequent clearing could create some
frost/freeze potential north of the I 96 corridor.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 730 PM EDT Sat Apr 13 2024
Primary aviation concern over the next 24 hours is LLWS. Strong
LLWS develops at all terminals after 03-04z tonight around 40-45
knots, and peaks around 50-60 knots below 2000 ft after 05z. The
strongest winds at 2000 ft will be in the 07-10z timeframe before
LLWS subsides around 12-14z, lasting longest for JXN/BTL/AZO.
Southerly winds of 5-10 knots this evening become west-
northwesterly at 10-15 knots Sunday morning with gusts of 20-25
knots expected early Sunday morning through near the end of the
TAF window. Otherwise, VFR conditions are expected with no cigs or
cigs above 20000 ft expected at all TAF sites. Given the dry air
in place, showers should remain north of the TAF sites except for
the chance of showers approaching the vicinity of MKG overnight.
&&
.MARINE...
Issued at 303 PM EDT Sat Apr 13 2024
Southwest winds and waves may briefly approach Small Craft
Advisory criteria late tonight into early Sunday morning, but
overall the stronger gusts are not expected to mix down to the
surface. There is a low chance for an isolated shower or storm
tonight, but better chances look to be north of Pentwater. Winds
are then expected to shift to the northwest behind the front
Sunday morning and into the afternoon. Small Craft Advisory
conditions look to hold off until Tuesday when southeasterly
winds build with our next chance for showers and thunderstorms.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
UPDATE...Meade
DISCUSSION...Ceru/RAH
AVIATION...Thomas
MARINE...RAH
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
715 PM EDT Sat Apr 13 2024
.KEY MESSAGES...
- Mostly Clear and Mild tonight.
- Partly cloudy and warmer on Sunday; Breezy
- Chance for an afternoon and evening shower or storm mainly east on
Sunday.
- Ongoing River Flooding
- Multiple rounds of showers storms next week, severe weather
possible Tuesday and Wednesday
- Cooling trend late next week.
&&
.FORECAST UPDATE...
Issued at 715 PM EDT Sat Apr 13 2024
A low-amplitude shortwave trough within the polar jet is seen in
water vapor channel imagery over Saskatchewan now and will pass
through the Great Lakes early tomorrow. Preceding this will be
strengthening low-level flow across our area and modest moisture
advection leading to warmer conditions tonight. Midlevel clouds from
the wave`s modest moisture connection and ascent will pass through
late tonight and early tomorrow. Statistical, raw, and blended
guidance are clustered fairly tightly for temperatures tonight, so
no adjustments are needed. Our temperature forecast tomorrow is at
about the 75th percentile which given warm plume advecting in and
mixing is reasonable.
Looking at the latest model data for tomorrow`s convective
potential, there is little change in our thinking, but perhaps
slightly more pessimistic. The aforementioned wave will nudge a
weakly baroclinic cold front into central Indiana, but forecast
soundings show a capping elevated mixed layer present. With
ascent/cooling from aforementioned shortwave already having passed,
the only mechanism for convective development would be (1) enough
moistening and heating of the PBL, which does not look sufficient
given the magnitude of the EML, and/or (2) frontal convergence.
Since LCL-LFC layer winds are parallel to the front keeping parcels
from detraining away from mesoscale ascent and convective-scale
repeated moistening/cooling, it`s possible that isolated
thunderstorms could develop. Longevity is likely to be limited given
the hostile thermal environment and any convection that does form
would diminish with loss of diabatic surface heating by mid-evening.
&&
.SHORT TERM (This evening through Sunday)...
Issued at 253 PM EDT Sat Apr 13 2024
Synopsis:
Surface analysis this afternoon shows high pressure centered over
the Gulf Coast, with a ridge axis extending north across western KY
and the Wabash Valley to Lake Michigan. This was resulting in dry
westerly flow across Central Indiana. GOES16 shows clear skies
across Indiana and much of the region due to the ongoing subsidence
with the approach of an upper ridge exiting the Rockies. Dew points
were dry, mainly in the 30s. Meanwhile a weak surface low, failing
to produce any precipitation and little cloud cover was found over
the Dakotas.
Tonight...
Quiet, dry weather is expected tonight. The surface ridge over the
Wabash is expected to continue to drift east, reaching Appalachia
and the east coast by Sunday. Warmer southerly flow is expected to
develop overnight on the backside of the ridge. Furthermore a
moderate pressure gradient aloft is expected to develop, allowing
for some mixing to persist overnight. Meanwhile aloft, northwest
flow is expected to remain in place as ridging aloft remains over
the Plains states, continuing to provide some subsidence, keeping
the mid and lower levels dry. Forecast soundings reflect this, only
showing some high clouds passing overnight within the upper flow,
Thus have trended the forecast toward a partly cloudy sky. Since
warm air advection and some mixing will remain in play, a mild night
is expected with lows falling only to the middle and upper 50s
Sunday and Sunday Night...
Quiet weather is expected to start the day as conditions from the
previous night remain relatively unchanged. The weather feature of
concern on Sunday afternoon and Sunday evening will be related to
the previously mentioned Dakota surface low. This feature is
expected to pass well north of Central Indiana overnight, reaching
NY state by Sunday afternoon. As this occurs, a weak cold front is
expected to sag southward, trailing the low. This weak front looks
to have limited moisture, and really appears to be a cusp like
feature on the tail of weak cold front.
Forecast soundings on Sunday afternoon and Sunday evening suggest
attainable convective temperatures resulting in CU development.
However a mid level inversion remains in place. Farther aloft,
elevated CAPE around 1000 J/KG will be present above the cap. Pwats
appear near 1 inch are available should the cap break, but the
inversion appears strong. Aloft no forcing is available to help add
a lifting element. Thus any showers/storms will be mainly driven by
weak lower level convergence and daytime heating. The cap should be
weakest in parts of far eastern Central Indiana during the afternoon
and early evening. HRRR suggests some development across the eastern
parts of the forecast area at that time. Overall, confidence is low
for this event, but given the weak signal, small chc pops during the
afternoon and evening appear reasonable.
Given the southerly flow and mixing expected through the course of
the day, as well as plentiful sunshine and heating through early
afternoon, highs in the upper 70s to lower 80s will be possible.
On Sunday night after any of the precipitation ends, partly cloudy
skies will linger as weak high pressure from the north once again
settles across the area. A significant change in air mass is not
expected, leading to another night of low temperatures on Sunday
night in the upper 50s to around 60.
&&
.LONG TERM (Sunday night through Saturday)...
Issued at 253 PM EDT Sat Apr 13 2024
Monday through Wednesday...
Look for the long term period to start off relatively quiet as a
weak cold front settles near far southern portions of central
Indiana by daybreak Monday. This may keep highs slightly cooler than
Sunday, but dewpoints in the mid 40s to low 50s behind the front
should be more noticeable. Greater PBL moisture over far southern
counties could promote isolated showers and thunderstorms once
sufficient daytime heating occurs. If storms develop, moderate
destabilization combined with effective bulk shear around 25-35 kts
support a few strong-severe storms. The main threats would be
damaging wind gusts or large hail. Confidence in this severe
potential is low at this time because of questions regarding
convective coverage due to weak forcing and where the front stalls.
Expect any diurnally driven convection to dissipate during the
evening hours.
Rain chances increase late Monday night into Tuesday as a surface
low associated with a negatively tilted trough approaches the
region. Strong diffluence aloft and isentropic ascent/warm air
advection suggest showers and storms are likely during this
period. There is a chance some of these storms could be strong to
severe, but the greater severe threat appears to be from Tuesday
evening into Wednesday as a somewhat narrow corridor of stronger
low- level theta-e advection occurs ahead of a cold front moving
in. Strong deep-layer shear and destabilization from warm-moist
advection supports the potential for severe weather well into the
overnight hours. Some uncertainties still remain in exact details.
These finer details should become clearer over the next 24-36
hours once higher resolution models begin to resolve this setup. A
strong pressure gradient from the aforementioned system
traversing the region will result in windy conditions Tuesday and
Wednesday. Increasing southerly flow is going to help keep
temperatures above normal.
Thursday onward...
Precipitation chances linger through the extended period due to
broad upper troughing. The best chance for additional rain looks to
be late Thursday as another cold front moves through. Temperatures
dropping into the 30s raises the concern for frost by late week
though winds look to remain elevated at this time. Highs are
expected to drop into the 50s for many areas on Friday with cold air
advection over central IN.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 630 PM EDT Sat Apr 13 2024
Impacts:
- Non-convective low level wind shear tonight
Discussion:
VFR conditions will prevail. Mid-clouds well within VFR category may
be observed later tonight through part of tomorrow, followed by some
lower cumulus (still VFR). Any thunderstorms Sunday evening should
be east of TAF sites.
Models have a low-level jet forming at inversion top tonight. Given
the type/character of this setup, we think a slightly thinner non-
convective low level wind shear layer may happen with 50-knot wind
around 1,500 feet. Core of the low-level jet will pull away by mid-
morning and mixing will increase surface winds lessening the
contrast within that layer.
A weak cold front will bring a shift to northerly winds toward the
end of the TAF period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...BRB
SHORT TERM...Puma
LONG TERM...Melo
AVIATION...BRB
Area Forecast Discussion
National Weather Service Marquette MI
632 PM EDT Sat Apr 13 2024
.KEY MESSAGES...
- Scattered showers developing late afternoon into tonight with
maybe a few thunderstorms possible along WI border and south
central. Overall rain amounts 0.05 to 0.20 inch, highest
across the Keweenaw and eastern UP.
- Mostly dry weather through Tuesday morning. RHs fall to around
30% in the interior west Sunday and Monday, causing some fire
weather concern.
- A low pressure tracks through the Upper Great Lakes during
the midweek, causing widespread rain showers.
- Chances of precipitation remain possible (~50%) into the late-
week, though uncertainty exists on timing, intensity, and
precipitation type.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 317 PM EDT Sat Apr 13 2024
Afternoon RAP analysis shows the weak ridge axis shifting east of
the area, ahead of a weak shortwave moving along hte Ontario/MN
border. Rather dry midlevel air is apparent on water vapor over the
Great Lakes , but deeper moisture is present with the approaching
shortwave. WAA out ahead of this, with a tight theta-e gradient
draped from the UP northwest through the Arrowhead of MN, has
touched off some weak convection that is finally moving across Lake
Superior and the western and north-central UP UP. That said, with
steep surface dewpoint depressions on the order of 20 degrees, and
very dry afternoon NUCAPS soundings, weak radar returns do not
appear to actually be reaching the ground. Apart from the broken
cloud cover streaming in, would expect no more than some sprinkles
or a stray light rain shower the rest of the afternoon.
Otherwise, temperatures are climbing well into the 50s so far across
the western half of the UP, while northerly flow off of Superior is
keeping the eastern UP comparatively cooler, in the lower to mid
50s. The Keweenaw, Meanwhile, is struggling even to get out of the
40s. Across the western half of the UP, we should see many spots
peaking in the 60s while elsewhere temperatures aren`t expected to
budge much more.
Showers continue to stream into the area this evening ahead of the
approaching shortwave, generally along and north of the theta-e
gradient analyzed over the area. This track would largely keep
showers limited to the northern half of the UP before the shortwave
drops through from 03Z onward. Coverage of showers expands ahead of
the associated cold front, with some dynamical support as the right-
exit region of the upper jet streak becomes directed over the area.
However, showers quickly wrap up from 06Z onward as the front moves
out. Weak, elevated instability apparent in soundings will lead to a
chance for some rumbles of thunder across the south-central UP, with
some heavier embedded rainfall amounts possible in storms.
Otherwise, would expect the highest rainfall totals overnight to be
across the Keweenaw, through the north-central and eastern UP. heavy
rainfall is not expected, with amounts topping out below a quarter-
inch.
Skies clear out behind the passing front, but temperatures stay
fairly mild overnight with most of the area bottoming out in the
mid and upper 30s.
&&
.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 438 PM EDT Sat Apr 13 2024
The extended forecast starts out dry with good agreement in the
model guidance of a more wet and active period for mid next week. A
mid level closed low over CA on Sunday makes its way eastward over
the Rockies by Monday night, lifting northeast over the Central
Plains through Tuesday. Meanwhile, a trough sets up in the Canadian
Prairie Provinces with a east-southeast track set for the rest of the
week. These features continue their trajectories into the Upper
Midwest/Great Lakes, phasing together Wednesday/Wednesday night. The
resulting closed low/trough will then progress eastward through the
weekend as ridging builds back over the western U.S. This is where
guidance begins to really diverge, but northwest flow over the Upper
Great Lakes with shortwaves riding through the region provide
additional chances for precip this weekend into next week.
Starting Sunday, the shortwave fueling tonght`s precip chances will
be located over the northern end of Lake Superior. While model
soundings show low level moisture in the lowest 5kft in the morning
(also visible in PWATs with values around 0.4" to 0.5"), the
shortwave`s associated PVA remains north of the CWA. Drier northwest
flow also erodes the low level moisture, lowering PWATs by ~0.1"
while q-vector divergence is noted over the UP. Overall, this likely
will delay the low level clouds off Lake Superior from clearing as
the shortwave departs to the southeast, but the area will stay dry.
Despite the lingering cloud cover, dry mid levels will help mix down
lower dew point temps, especially in the southern half of the UP.
This would causing RHs to tank in the afternoon, especially in the
interior west near the WI/MI state line where low level lapse rates
approach 6-7C/km. With highs in the upper 40s to mid 50s near Lake
Superior and mid 50s to possibly upper 60s in the interior, min RHs
will be in the upper 20 to mid 30% range. With wind gusts around 15
to 20 mph, counties bordering WI flirt with elevated fire weather
conditions. Will need to monitor these conditions as we get closer.
With sfc high pressure building in from the northwest Sunday night,
dry weather and light winds continue. Temps fall into the 30s.
Dry weather holds through Monday with mid level ridging building
into the region and sfc high pressure extending over the Upper Great
Lakes. While the right entrance region of the upper level jet
approaches the CWA from the southwest during the day, there is no
significant shortwave providing PVA. Also weak q-vector convergence
looks to remain outside the CWA, yielding little to no forcing for
precip. This continued dry weather increases the fire weather risks
as low level lapse rates approach 7-8C/km and model soundings show a
significantly dry profile. Expect another warmer than normal day
with highs near Lake Superior in the low to mid 50s and mid 50s to
mid 60s for the interior. Lower dew points mix down again during the
afternoon yielding min RHs in the mid 20 to 30% range. Luckily, fire
weather concerns will be lower as winds are expected to be lighter
than Sunday, staying below 15 mph. Regardless, fire weather partners
should continue to monitor this for changes. Temps fall back into the
30s (coldest east) Monday night as clouds increase from the
southwest ahead of the next system.
Moving on to the midweek system, the southern stream deep trough
will be positioned over Plains Tuesday morning while the northern
stream trough will broadly span British Columbia and Alberta. The
southern trough lifts northeast through Tuesday night toward the
Upper Great Lakes while the northern one forms a closed low over
Saskatchewan. Cyclogenesis begins on the lee side of the Rockies on
Tuesday. The sfc low then weakens as it follows the southern trough
into the Great Lakes for Wednesday and Wednesday night. Dry weather
looks to maintain during the day Tuesday, with showers then lifting
north over the UP Tuesday night and Wednesday when the better WAA,
PVA, and q-vector convergence arrives. NBM PoPs then drop off
Wednesday night as dry northwest flow drastically diminishes
available moisture; PWATs around 1" drop to ~0.3. However, with the
current uncertainty in the guidance surrounding the trough/closed
low`s track east through Canada/Great Lakes late next week and into
the weekend, NBM PoPs were left around 20-50% Thursday into the
weekend. Winds will be worth monitoring as NBM shows gusts around 25-
35 mph Tuesday through Wednesday. Another thing to watch with the
late week precipitation relative to the mid-week system will be
precip type. Uncertainty remains high at this time, but GFS and EPS
probabilities of at least 1 inch of snow begin increasing Thursday
night into Friday with around 20-40% by 0Z Saturday.
Additional shortwaves then ride the northwest flow over the Upper
Great Lakes late this weekend into early next week bringing
additional chances for precip. Confidence remains low with the given
spread in the guidance at this time.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 632 PM EDT Sat Apr 13 2024
VFR conditions prevail through the period for IWD and for most of
the period at SAW. SAW will see some fog late tonight which will
bring it down to MVFR for a couple hours. CMX will have rain which
will help to bring in an MVFR deck by late Sun morning off of Lake
Superior which will lower to IFR/LIFR by Sun afternoon.
&&
.MARINE...
Issued at 438 PM EDT Sat Apr 13 2024
Winds late this afternoon into the evening hours will become
northeast as a weak low pressure system tracks east into the Great
Lakes. However, winds are expected to remain below 20 kts through
Monday with high pressure building southeast into the Upper Great
Lakes Monday, holding into Monday night. Our attention then turns to
a stronger low pressure system mid week. This system looks to eject
off the Rockies Monday night, lifting northeast into Wisconsin by
Wednesday afternoon as it weakens slightly. The low then continues
northeast through the Great Lakes Wednesday night with troughing
swinging behind it over Lake Superior Thursday/Friday. East gales
are likely (60-90% chance of gusts exceeding 34 kts) over the west
Tuesday afternoon, expanding eastward over the lake into Wednesday
as the system moves through. Winds remain around 20-30 kts Wednesday
night into the weekend, quickly becoming westerly behind the low
Wednesday night. Winds then veer northwest Thursday night/Friday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Small Craft Advisory until 8 PM EDT this evening for LSZ251.
Lake Michigan...
None.
&&
$$
SHORT TERM...LC
LONG TERM...Jablonski
AVIATION...07
MARINE...Jablonski