Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/15/21
Area Forecast Discussion
National Weather Service La Crosse WI
1040 PM CDT Tue Sep 14 2021
.SHORT TERM...(This evening through Wednesday night)
Issued at 225 PM CDT Tue Sep 14 2021
An upper-level trough over the region will continue to propagate to
the east into the overnight hours helping high pressure build
overhead. As high pressure moves in, skies will clear out helping
low temperatures drop into the low 40s to low 50s. Near-surface
(above 900 feet) winds of 10-20 knots until the morning hours will
likely prevent widespread valley fog, but patchy fog in the valleys
and tributaries cannot be ruled out. If the near-surface winds
weaken earlier than the models are predicting, valley fog could
become more widespread.
High pressure will continue tomorrow, providing mostly sunny skies
and slightly warmer temperatures with highs in the low to mid 70s.
Southerly winds pick up heading into the evening hours with gusts up
to 18 mph. Gusty surface winds will limit the formation of valley
fog Wednesday night.
.LONG TERM...(Thursday through Tuesday) Issued at 225 PM CDT Tue
Sep 14 2021
Our next chance of storms occurs Thursday night into Friday when an
upper-level positively tilted trough transitions across our northern
periphery. Primary upper-level dynamics remain situated around an
area of lower potential heights way up in northern
Saskatchewan/Manitoba. The GFS and ECMWF deterministic models
indicate southwesterly surface warm air advection reaching our
forecast late Thursday evening. The primary CAPE axis remains
alongside the cold front in eastern SD/southwestern MN peaking in
intensity Thursday evening. While strong (30-40kts) low-level (0-
1km) shear values prevail over our forecast area, deep-layer shear
stays (0-3 & 0-6km) post-frontal. With severe parameters out of
phase and diminishing CAPE with loss of diurnal heating, severe
potential does not appear high at this time.
The aforementioned separation between the primary upper-level and
lower-level dynamics leaves the associated surface frontal
boundaries slightly marooned; placing our forecast area in the
warm sector for most of the remaining forecast period. The surface
boundary sags during the day on Friday, bringing chances of
percolating precipitation for most of the day. Model disagreement
on location of surface boundary and extent of southerly sag will
differentiate placement of highest precipitation potential. Slight
upper-level perturbations along the southern edge of the jet axis
with sufficient mid-level vorticity advection and low-level lapse
rates >8.0C/km will provide favorable regions for ascent during
the day. In summary, the forecast has rain chances in the 30-50%
range, and there are some indications it could be more of a stormy
day. Some model solutions suggest CAPE pool building over 1000
J/kg during the afternoon near the front. A lack of wind shear
will likely limit severity, with stronger chances for heavy rains.
Any lingering isentropically forced rain chances Saturday morning
get blasted northeast by a more anomalous mid-level ridge for
September. Heights aloft are at the 97th percentile versus
climatology building Saturday into Sunday according to the
Canadian Ens, and ECMWF ens. The combination of this anomalously
strong ridging and continued warm sector southwesterly flow
results in forecasted 99th percentile low-level temperatures when
compared to climatology. EPS guidance contains little temperature
spread between members for Sunday with ensemble mean max
temperature into the mid 80s... and increased spread for Saturday
and Monday. It is expected to be unseasonably warm for Sunday, not
near record yet, with the possibility for record warm low
temperatures.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1040 PM CDT Tue Sep 14 2021
The signals for valley fog development overnight remain mixed. The
temp/dew point spread at KLSE increased slightly between 02Z and
03Z while northwest winds just above the surface remain around 20
knots. These winds aloft will be slowly decreasing overnight but
forecast soundings from both the RAP and 15.00Z NAM show these
staying at or above 10 knots until almost sunrise. The NAM
continues to indicate that saturation will occur at the surface
while the RAP does not achieve saturation. Because of the
uncertainty, will stay with a BCFG mention. Otherwise, VFR
conditions through Wednesday evening for both sites.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...KAA
LONG TERM...Baumgardt/JAR
AVIATION...04
Area Forecast Discussion
National Weather Service Goodland KS
521 PM MDT Tue Sep 14 2021
.UPDATE...
Issued at 253 PM MDT Tue Sep 14 2021
With storms developing off the Front Range, a Severe Thunderstorm
Watch has been issued for Kit Carson and Cheyenne counties in
east-central Colorado until 9 PM MT. Hazards include up to 2 inch
hail and up to 70 mph wind gusts.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 253 PM MDT Tue Sep 14 2021
An upper level trough will continue to move east across the Rockies
into the Great Plains this afternoon and evening. As the upper
trough moves through, shortwaves moving over the area will interact
with the front stalled to our south. As of 2 PM MDT, storms are
beginning to fire off the Front Range, moving east. Storms are
expected to move into our east-central CO counties between 4 and 5
PM. As mentioned yesterday, today`s environment is more supportive
of storms across the western half of the area. There is around 1000
J/kg of MLCAPE and 30-55 kts of westerly bulk shear. CAM soundings
have been trending more towards a straight hodograph with each run,
bringing some concern to storm splitting as the supercells approach
the area. Large hail, up to 2 inches, is a greater concern while the
storms remain isolated during the afternoon to early evening hours.
Damaging wind gusts up to 70 mph are also a concern with any storms.
The HRRR has the storms organizing into a cluster as they approach
the state line. A few landspouts may be possible in portions of Kit
Carson and Cheyenne counties; however, confidence is low compared to
the hail and wind threat. Most of the storms are expected to remain
along and southwest of a Wray to Goodland to Russell Springs line.
As these storms move across the area, they will also be capable of
producing accumulating hail and heavy rain given the decent amount
of low to mid layer moisture advecting into the region. Storms are
expected to move SE into southern Kansas around midnight. Once the
storms clear out, winds are expected to become nearly calm for the
remainder of the night. Overnight lows will be in the 50s.
With the moisture and calm winds, there is potential for patchy fog
to develop around sunrise. So far, the best chance for fog is east
of the CO border and is conditional to the precipitation expected
this evening. Dry conditions are expected as an upper level ridge
builds over the Four Corners and nudges east. Temperatures will
begin to warm up again tomorrow with highs in the mid 80s across
the Tri- State area. Thursday, the High Plains will be under SW
flow as an upper trough moves across MT, WY, and the Dakotas. Weak
shortwave disturbances will move across the Central Plains as a
lee trough strengthens along the Rockies. Dry conditions are
expected much of the day with elevated to near-critical fire
weather conditions possible across the CWA. A cold front will push
south into the area, bringing potential for rain and storms to
the northeast corner of the area late Thursday evening and into
the overnight hours. Highs on Thursday are forecast to be in the
upper 80s to lower 90s. Overnight lows Wednesday and Thursday are
expected to be in the 50s to mid 60s.
.LONG TERM...(Friday through Tuesday)
Issued at 130 PM MDT Tue Sep 14 2021
Friday...there is just enough moisture in the 850-500mb layer to
support a slight chance of showers and thunderstorms across the
eastern fringes of the forecast area during the day with the
remainder of the area expected to be dry. High temperatures are
forecast to be in the low 80s to around 90 with low temperatures in
the low 50s to low 60s.
Saturday...the forecast area is expected to be under southwest flow
aloft, in between a large upper level ridge building over the
eastern United States and an upper trough making its way into the
Pacific Northwest. There is little if any moisture in the 850-500mb
layer so we`ll be continuing with a dry forecast. High temperatures
are expected to warm back up into the upper 80s to mid 90s. Low
temperatures fall into the mid 50s to mid 60s.
Sunday...the GEFS/GFS/ECMWF all show the Pacific Northwest trough
Saturday moving southeast toward Idaho and Nevada with the upper
ridge holding firm over the eastern United States. Very little
change in 850mb temperatures compared to Saturday so for now will
advertise high temperatures in the upper 80s to mid 90s. Low
temperatures are expected to be in the mid 50s to mid 60s. Moisture
in the 700-500mb layer increases a bit across the front range of the
rockies toward the western fringes of our forecast area but not
enough to support any precipitation mention.
Monday...the 12z GEFS/GFS/ECMWF move the above mentioned upper
trough axis east to the Continental Divide from Montana south
through Colorado. The mid level moisture west of the area Sunday
night moves east across the area during the day then slowly east and
out of the area after midnight. I believe the previous shift had
some thunderstorms mentioned as this moisture and what would likely
be a cold frontal passage combine to support the previous shifts
forecast. For now will keep things dry to keep in line with
surrounding offices. 850mb temperatures from the GFS/ECMWF/Canadian
models support afternoon temperatures probably hotter than currently
advertised. I did nudge temperatures up, especially east of the
CO/KS border with low 90s currently expected. Would not be
surprised if later shifts up them closer to the mid 90s. Low
temperatures drop into the upper 40s to low 50s in far eastern
Colorado, low to upper 50s elsewhere as a cold front moves
through.
Tuesday...the above mentioned upper trough axis is expected to move
east into the Tri-State area. GFS/ECMWF 850mb temperatures drop into
the 11C to 16C range. The current forecast has high temperatures in
the low 70s to around 80 degrees and would be very optimistic if the
850mb temperatures verify. Right now the forecast is dry but there
is some support and moisture available for some thunderstorms to
develop.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 514 PM MDT Tue Sep 14 2021
VFR conditions are expected through ~12Z Wednesday morning over
both KGLD and KMCK terminals. Easterly winds are expected to shift
south late this evening and into the overnight hours, becoming
light. Patchy fog could develop shortly after 12Z over both
terminals, with visibility dropping to 3SM or less for an hour or
two. If fog develops, it should begin to dissipate around 14 or
15Z. Southerly winds are expected to remain through the remainder
of the TAF period tomorrow, increasing to 10-15 kts with gusts
around 20 kts possible during the afternoon.
Showers and storms could move within the vicinity of KGLD over the
next several hours, mainly between 01Z and 04Z. These storms could
be severe and capable of producing large hail and damaging winds
up to 70 mph.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...KMK
SHORT TERM...KMK
LONG TERM...99
AVIATION...KMK
Area Forecast Discussion
National Weather Service New Orleans LA
914 PM CDT Tue Sep 14 2021
.EVENING UPDATE...
Tropical Depression Nicholas creeping along near the Texas-
Louisiana border this evening. Most of the CWA currently in a lull
in precipitation as some drier mid level air has worked in.
However, convective allowing models (00z runs) continue to show
redevelopment of significant precipitation near the Atchafalaya
River Basin in the next 3-6 hours, and gradually work its way
eastward. Will keep Flash Flood Watch in effect with current
messaging regarding amounts.
&&
.PREV DISCUSSION... /issued 403 PM CDT Tue Sep 14 2021/
SHORT TERM...Tropical Storm Nicholas is moving painfully slow to
the east and at times east-southeast today. Nicholas is not
anticipated to pick up any speed and this looks like it could lead
to a long night across portions of SELA and coastal MS. Rain has
been falling over the entire area all day but luckily it has been
more moderate rain with no extremely heavy bands yet. That said we
have seen widespread 2-3 inches of rain already with a few bands
of 3-4 isolated 5 inches and that one small area in EBR that is
now over 7 inches.
The forecast focus has not changed and remains on the potential for
flash flooding and possibly life threatening flash flooding. That
could be overnight tonight for a good chunk of SELA and then
possibly late Wednesday afternoon through Wednesday night for
coastal MS. That said confidence is low on any one location but high
that someone will get very heavy rain.
Tonight there is a lot of agreement that the next band of heavy rain
should begin to develop just off to our west and southwest around
22-00z and then slowly move east-northeast through the evening
and overnight hours. HRRR has been highlighting that potential for
a while and honestly it has preformed very well over the last 24
hours and currently is initialized well and already seeing
convection trying to get a little more invigorated from the TX/LA
border and southeast into the Gulf. This still isn`t expected to
really develop till closer to 23-00z. Looking at WV one would be
hard pressed to think additional heavy rain will develop and move
into the area, that said there is still abundant moisture to tap
into while lift and forcing are both expected to increase
overnight. As Nicholas continues to slowly slide east along a semi
warm front along the coast a LL jet will try to get going across
the coast and into the Gulf. The nose of it will punch into south-
central and then southeastern LA overnight. The nose of that will
increase the LL convergence which will combine with
WAA/isentropic lift while occurring with ample moisture in place.
PWs will still range from near 2.2 to possibly 2.5". There will
still be divergence aloft and this all suggest efficient rain.
This will still be primarily a warm rain process so don`t
anticipate extremely impressive towers or a lot of lightning. If
this band does get going as strong as it may then we will see
hourly rainfall rate of 2-3 inches per hour and possibly higher in
some areas with overnight totals of 5 inches and even greater in
isolated areas.
The heavy rain threat will slide east into coastal MS early tomorrow
with this band expected to continue to move east towards AL.
However, whatever is left of Nicholas will still be back in
southwest or south-central LA and very deep moisture will remain in
place. By tomorrow afternoon a line of additional storms could
develop from southwest to northeast from coastal SELA to coastal MS.
This will bring another round of moderate to heavy rain and after
everything finally starts to wind down some we could see widespread
5-10 inches of rain with locally higher amounts possibly even over
20 inches. 20 inches of rain would be a major problem but as long as
it doesn`t fall mostly in one round the flash flooding may not be as
life-threatening. Most of this rain is anticipated to fall along and
south of the 10/12 corridors but if it occurs just north of the
interstates in SELA and across coastal MS river flooding will be a
concern. We still are under a Moderate Risk for excessive rainfall
tonight and through Wednesday night. There is a small chance we
could see a High risk depending on what occurs tonight.
Going into Thursday numerous to widespread showers and embedded
thunderstorms will continue to plague the region. Nicholas should be
dissipated by then but we will still be embedded in very deep
moisture and lower hghts aloft. The one positive is we should not
see any focused bands but heavy rain will still be possible and thus
flash flooding will still be a concern.
Coastal Flood Advisory was expanded to include the rest of the LA
coast outside of the tidal lakes and Hancock and Harrison county.
Still looking for 1-2 feet above astronomical. /CAB/
LONG TERM...Again no major changes in the extended as the
focus is on the short term. Appending previous long term portion of
the discussion handling the forecast for Friday and into the
following work week. /CAB/
Previous Long Term...Still some uncertainty in the extended portion
of the forecast regarding the eventual disposition of Hurricane
Nicholas. Current NHC forecast (10 PM CDT Monday) has it dissipating
over south-central or southwest Louisiana Thursday. That being said,
at this time, don`t see much in the way of drying forecast in the
column as a whole into and through the weekend. Convective
development will likely occur during the more usual diurnally
favored hours (afternoon over land) over the weekend. May see some
decrease in areal coverage by Monday or so.
Don`t see much day to day change in temperatures until the expected
decrease in areal coverage around Monday or so, at which time temps
may creep upward a degree or two. /35/
AVIATION...18Z TAF DISCUSSION...Obviously main issue is rain, low
cigs, reduced vsbys, and even gusty winds. The low cigs will
continue through the night and with rain the vsbys will be reduced.
All terminals will be impacted and likely all will deal with
significant impacts for at least the next 12-18 hours. /CAB/
MARINE...Hazardous winds and seas will continue over the coastal
waters through tonight. winds of 15-20kts with frequent higher gusts
will continue but the bigger concern could be combined waves and
swells leading to total sea hghts of greater than 7` still.
Obviously higher winds and seas are expected with any thunderstorm
over the coastal waters.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 70 79 70 83 / 100 90 60 80
BTR 71 80 70 84 / 100 90 60 80
ASD 73 83 72 87 / 100 90 70 90
MSY 75 86 76 88 / 100 90 70 90
GPT 73 82 74 85 / 100 90 80 90
PQL 71 82 72 85 / 100 100 80 90
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Flash Flood Watch through Thursday morning for LAZ034>037-039-
046>050-056>061-063>072-075>078.
Coastal Flood Advisory until 7 AM CDT Thursday for LAZ064-
066>070-076-078.
GM...Small Craft Advisory until 7 AM CDT Wednesday for GMZ550-552-555-
557-570-572-575-577.
MS...Flash Flood Watch through Thursday morning for MSZ068>071-077-
080>082.
Coastal Flood Advisory until 7 AM CDT Thursday for MSZ080-081.
GM...Small Craft Advisory until 7 AM CDT Wednesday for GMZ552-555-557-
570-572-575-577.
&&
$$
Area Forecast Discussion
National Weather Service Louisville KY
1001 PM EDT Tue Sep 14 2021
.Forecast Update...
Issued at 1001 PM EDT Tue Sep 14 2021
A narrow broken band of showers and thunderstorms has developed this
evening along and just ahead of a cold front stretching roughly from
Detroit to St Louis to Wichita in conjunction with a weakly digging
5H trough. The convection is within a corridor of 1.7-1.9"
precipitable water values that will sink southward with the front
tonight, eventually meeting up with a similarly humid atmosphere
already in place over Kentucky by morning.
An upper jet from the Midwest to the eastern Great Lakes will
intensify overnight and the Ohio Valley will increasingly be under
its right entrance region...especially on Wednesday.
ACARS sounding out of SDF a couple of hours ago still showed a
healthy mid-level cap overhead, but sounding progs show it weakening
overnight with cold air advection in the 5H-7H layer associated
with the advancing upper trough to our northwest.
RAP data accordingly show CIN decreasing overnight. Fortunately any
low level jet tonight looks to be weak, effective bulk shear will be
very weak, and lapse rates are weak at the surface and aloft with
CAPE on soundings showing up as tall, thin, and slightly elevated.
So, given the forcing, moisture, and available instability ahead of
the advancing front, will hold on to scattered showers and storms in
the forecast during the late night hours. Not everyone will see
rain, as evidenced by the large gap that has opened up in the line
over the Wabash Valley. The latest HRRR and 3km NAM capture this
well and actually bring little if any rain into the LMK CWA...but
would prefer to keep PoPs in the forecast given the aforementioned
moisture, forcing, and instability. Given the latest, will reduce
PoPs but not entirely eliminate.
&&
.Short Term...(This evening through Wednesday)
Issued at 245 PM EDT Tue Sep 14 2021
Isolated to widely scattered showers have developed across south-
central and western Kentucky this afternoon. Capping near 700mb has
limited overall growth and strength of these convective showers,
resulting in most echo tops not going beyond 20kft. Up to this
point, very little to no lightning activity has been detected in
this precipitation, and environmental conditions will not change
much over the next several hours, so expect any thunderstorm
activity to be largely isolated. One thing to keep an eye on this
afternoon is high DCAPE (>1,000J/KG) values across the region where
gusty winds could be possible in the stronger showers or isolated
storms, assuming they can overcome the warmer air/cap around 700mb.
We should see a break in the action near sunset as diurnal heating
wanes and convective showers taper off. A broken line of storms
forming ahead of a cold front this evening will then race toward our
region, potentially arriving after midnight. Much of this activity
will weaken by the time it approaches us, and any severe threat will
be very low with the line. Though unlikely, it is entirely possible
the line could dissipate before it reaches our southern IN counties
as a couple of CAMs show (3km NAM, WRF ARW). Model soundings do show
elevated instability persisting through much of the overnight and
early morning hours tomorrow, so will keep mention of storms in the
forecast as outflow boundaries from weakening convection could
generate new storms.
The cold front should reach our southern Indiana counties close to
sunrise tomorrow and gradually push through the region during the
day. As the front moves through, we could see additional development
of showers and storms along it. Depending on how much clearing we
see in the wake of the first round of showers/storms, there may be a
low-end severe threat for gusty winds and small hail with storms
that fire off along the cold front. SPC Day 2 Marginal covers that
threat area well.
.Long Term...(Wednesday night through Tuesday)
Issued at 255 PM EDT Tue Sep 14 2021
At the start of the extended period, expect to find the upper level
trough exiting east out of the area while the associated surface
front initially draped along the Ohio River Wednesday night
gradually sinks southward through the Commonwealth, likely washing
out in our vicinity. Showers and storms will be ongoing Wednesday
night ahead of and along the cold front with precip chances tapering
off from north to south overnight as the frontal boundary moves
through.
The end of the week will then feature ridging off of the East Coast
over the Atlantic while an upper trough lifts northeast across
central Canada, placing our region in relatively weak flow aloft.
Although the remnants of Nicholas are expected to remain well to our
south, will see lingering moisture across southern portions of the
area on Thursday associated with the washed out frontal boundary
then increasing moisture across the area Friday as we return to
southerly flow, keeping PWATs in the 1.2 - 1.6 inch range through
the remainder of the period. In a warm and marginally unstable
environment, cannot rule out isolated to scattered showers and
storms during the afternoon and evening hours Thursday into the
weekend. PoPs on Thursday will be confined to southern KY where the
better moisture is with precip chances then spreading across the
entire area the other days. By Sunday, as broad upper ridging moves
in over the east-central CONUS, expect mostly dry weather.
Temperatures will warm slightly through the period, with highs
initially in the lower to mid 80s Thursday then into the mid to
upper 80s by Sunday. Low temperatures will generally be in the mid
to upper 60s.
&&
.Aviation...(00Z TAF Issuance)
Issued at 731 PM EDT Tue Sep 14 2021
This evening a cold front is stretched out along a APN-CMI-SGF line
with a narrow broken band of showers and thunderstorms along and
just ahead of it. These features will sink southward tonight,
bringing showers and scattered storms to southern Indiana and
central Kentucky in the early hours of Wednesday.
Showers and storms will decrease in intensity and slightly in
coverage during the daylight morning hours Wednesday but then
renewed convection may develop in the afternoon, primarily affecting
LEX and BWG.
Forecast confidence is low on ceilings. Timing of showers and storms
will need to be adjusted as the system approaches.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...13
Short Term...DM
Long Term...KDW
Aviation...13
Area Forecast Discussion
National Weather Service Melbourne FL
936 PM EDT Tue Sep 14 2021
.DISCUSSION...
Easterly flow regime quickly transitioned most of the showers and
storms toward the western side of the FL peninsula this afternoon
and evening. However, some residual boundaries have helped a
couple of showers to develop north of Orlando, and this could
continue over the next couple of hours across the interior,
although coverage is expected to be much lower than what the HRRR
is currently depicting.
Otherwise, isolated to scattered showers will continue over the
Atlantic, and the 10 knots of low-level easterly flow currently
being sampled on the 915 MHz wind profilers should be sufficient
enough to occasionally push some of these showers onshore this
evening and through the overnight hours.
Have kept in a 20% PoP across the interior through midnight or
so, and the inherited 20% along the coast through the rest of
tonight looks good.
&&
.AVIATION...
VFR conditions outside of convection through the TAF period. East
winds are expected to bring showers occasionally onshore from the
Atlantic through tonight, so will keep VCSH mention at all
coastal terminals. For Wednesday, scattered showers/storms will
develop by early to mid afternoon, becoming numerous toward the
interior terminals through early evening. TEMPO IFR/MVFR
restrictions are possible, and these have been included at LEE but
will likely be needed toward ISM-MCO-SFB as well.
&&
.MARINE...
Rest of tonight...No change to the forecast needed. E/ESE winds
will continue at around 10 knots across the waters with seas of
2-3 ft.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 75 89 75 89 / 20 40 20 50
MCO 75 91 75 92 / 20 60 30 60
MLB 76 89 75 89 / 20 40 20 50
VRB 75 90 74 91 / 20 40 20 50
LEE 75 91 75 91 / 20 60 30 50
SFB 75 90 74 91 / 20 60 20 50
ORL 75 90 75 90 / 20 60 30 60
FPR 73 89 72 90 / 20 40 20 60
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Combs/Rodriguez
Area Forecast Discussion
National Weather Service Marquette MI
625 PM EDT Tue Sep 14 2021
.SHORT TERM...(This evening through Wednesday)
Issued at 409 PM EDT TUE SEP 14 2021
GOES wv imagery and RAP analysis show a vigorous shrtwv and
associated deepening sfc low ENE of Lake Superior this aftn as winds
have changed to the NW and gusts are starting to diminish. Although
the pressure gradient has diminished, pressure rises of around
2mb/hr will keep some gusty winds around through the early evening
hours across Upper Michigan. As this low pulls away, deep moisture
has exited the UP, but there are some instability showers and light
drizzle lingering...so have opted to leave some sprinkles in the
fcst through the evening hours across the west and central.
Tonight, drier air will continue to shift into Upper Michigan as
evidenced by some scattering ceilings across the area and clear
skies upstream across MN. While some areas may not see the sun
before the sun goes down, clearing skies will continue into this
evening. Despite some cooler air aloft moving in, clear skies should
allow enough of an inversion to develop to calm winds down tonight.
Look for temperatures to dip into the 40s interior to low 50s along
the lakes.
Drier air moving in tonight should set the stage for a good mixing
day on Wednesday. While generally light winds are expected, RH
values should fall into the mid to upper 30 percent range as highs
climb into the mid 60s to low 70s with 850mb temps near 8-9C. As WAA
looks to move in towards tomorrow night, there could be some higher
clouds moving into the western UP late...but otherwise diurnal cu
should be all the clouds we see during the day.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 321 PM EDT TUE SEP 14 2021
Quasi-zonal flow will transition to a more amplified pattern by
early next week. This will translate our region from a quiet period
to one with a few opportunities for rain showers through the
extended. Temps during this period should start out near normal to
slightly above normal, before potential record challenging temps by
next week.
Beginning Wednesday night, a weakening shortwave will progress
eastward in zonal upper level flow. The weak isentropic ascent
associated with a weak warm front looks to lift northeast through
MN. It could support some shower activity across the lake and parts
of the west. Overall lows should be in the 50s, with some places in
the traditional cold spots potentially dipping into the 40s. By
Thursday, increasing moisture advection within the WAA regime ahead
of an approaching cold front will support a warmer day with highs in
the mid-upper 70s. Some showers also can`t be ruled out in the west.
A cold front is progged to move through the region on Friday. Precip
out ahead of it will be the next best chance for widespread rain.
High pressure building in afterwards looks to support a dry and
seasonable Saturday. Upstream on Saturday though, an amplifying
shortwave and deepening surface low lifting northeast out of the
Rockies into the Canadian Plains will begin to take shape as it
continues gradually shifts through Ontario on Sunday. Impacts here
will be southerly flow advecting in a warm airmass into the region.
Deterministic 850mb temps among the guidance suite climb to near 20C
by Sunday afternoon. Pattern suggests this warm airmass, with
potentially record challenging/breaking warmth, could stick around
into Monday/Tuesday. Following this, signals for a potentially
vigorous system seems to be taking shape, but guidance seems to
present a good bit of uncertainty in the placement, timing and
intensity of the mid-week system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 625 PM EDT TUE SEP 14 2021
Conditions are expected to improve through MVFR to VFR this evening
as drier begins to move in from the west.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 409 PM EDT TUE SEP 14 2021
As a deepening low pulls away to the NE this evening, NW winds to
around 25 knots will continue. With high pressure shifting in from
the west later on tonight, winds will begin to back more westerly,
remaining near 20 knots until tomorrow morning. High pressure will
move overhead on Wednesday as a trough approaches and stalls to the
west. This will back winds to the SW Wednesday aftn, increasing from
the SE to S Wednesday night btwn 25 to 30 knots across the west and
central. A weak cold front will cross the lake on Friday, with light
NW winds moving in behind it.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 8 PM EDT this evening for MIZ005-
006-014.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JAW
LONG TERM...JP
AVIATION...07
MARINE...JAW
Area Forecast Discussion
National Weather Service Norman OK
1059 PM CDT Tue Sep 14 2021
...New AVIATION...
.UPDATE...
Issued at 854 PM CDT Tue Sep 14 2021
Kansas storms have been staying north of the border, with any
approaching showers quickly dissipating before crossing.
Meanwhile, convection in southeast Colorado and eastern New Mexico
has been thus far underwhelming. Latest HRRR runs concur with this
trend, being much less aggressive in bring storms into our area.
Therefore, have reduced PoPs through the morning hours.
Day
&&
.SHORT TERM...
(This evening through Wednesday)
Issued at 248 PM CDT Tue Sep 14 2021
The cold front in Kansas will shift toward the Oklahoma border this
evening. There are some building cumulus in northwestern
Oklahoma, but most of the development has been elevated and
farther north in Kansas so far.
The timing trends continue to slow the storm timing for our forecast
area. There may be some convection hovering near or just north of
the Oklahoma-Kansas border this evening near the surface front,
but much of this may stay north of the border. Higher chances of
storms will be with storms rolling off the High Plains of Colorado
this evening and moving east-southeast toward northwestern
Oklahoma. The convective-allowing models have differing ideas of
the evolutions of these storms with the HRRR being the most
aggressive in bringing these into northwestern Oklahoma tonight
with the GFS also showing some QPF into the area, but most of the
models dissipate the convection before moving into the area. So
have delayed the precipitation chances in the area and reduced the
POPs somewhat in general with these model trends.
There will be some elevated instability this evening, so there will
be a window in time for some strong or marginally severe storms this
evening, but the potential will decrease in the early morning hours
with decreasing instability.
&&
.LONG TERM...
(Wednesday night through next Monday)
Issued at 228 PM CDT Tue Sep 14 2021
The long term should be dry through the remainder of the week and
into the weekend. Mid-level ridging will set in over the Southern
Plains, and warmer temperatures will accompany it. High
temperatures should gradually rise into the mid 90s this weekend.
Early next week, a strong mid-level trough will move across the
Central/High Plains. An attendant cold front will sweep through
Tuesday afternoon and overnight. Showers and thunderstorms are
possible along this cold front as it moves through OK, but
confidence in coverage and timing is low at this time.
Temperatures early next week behind the front could cool down
substantially relative to this weekend`s temperatures, where
highs could be in the lower 80s across the area.
&&
.AVIATION...
(06Z TAFS)
Issued at 1040 PM CDT Tue Sep 14 2021
Outflow from the Kansas storms should bring a brief north /
northeasterly wind shift to northern TAF sites. A few isolated
storms may impact northwestern Oklahoma overnight. Otherwise, VFR
conditions and light (somewhat variable) winds should continue
outside of any convection.
Day
&&
.UPPER AIR...
Issued at 228 PM CDT Tue Sep 14 2021
No Upper Air flights are planned at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 89 67 88 66 / 0 10 10 0
Hobart OK 91 65 90 65 / 0 10 10 0
Wichita Falls TX 90 65 90 66 / 0 10 0 0
Gage OK 92 64 88 65 / 0 20 10 0
Ponca City OK 92 66 87 66 / 10 20 10 0
Durant OK 88 65 89 66 / 10 10 10 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
SHORT TERM...26
LONG TERM....13
AVIATION...14
Area Forecast Discussion
National Weather Service Tulsa OK
933 PM CDT Tue Sep 14 2021
...UPDATE...
.DISCUSSION...
Ongoing convection across south central KS is making very slow
progress east-southeast this evening. 00Z NAM and recent HRRR
output is less bullish bringing this activity into the region
overnight, and will lower and delay PoPs for the remainder of the
night across northeast OK/northwest AR.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 69 89 69 91 / 20 20 0 0
FSM 69 88 68 90 / 10 20 10 10
MLC 66 87 67 88 / 0 10 0 10
BVO 66 86 64 91 / 30 30 0 0
FYV 65 85 63 86 / 20 40 0 10
BYV 66 84 64 86 / 30 40 10 10
MKO 67 87 66 88 / 10 20 0 10
MIO 66 86 64 89 / 30 40 0 0
F10 66 89 66 89 / 10 10 0 10
HHW 67 87 67 88 / 10 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...18