Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/15/20
Area Forecast Discussion...Updated
National Weather Service Billings MT
840 PM MDT Tue Jul 14 2020
.UPDATE...
Thunderstorms have pushed south of Powder River and Carter
counties and will stay south of the region tonight as drier air at
the low levels move in. Removed pops for these areas and update
sent. borsum
&&
.DISCUSSION...
Tonight through Wednesday night...
A shortwave was pushing SE into SE MT early this afternoon. This
wave was producing a few showers and thunderstorms over the
Dakotas, Johnson County, WY and N of Fallon County. Mesoanalysis
showed 40-45 kt of Bulk Effective Shear over NE WY and near the
border in SE MT. MLCAPES were around 500 j/kg in this area. The
shortwave was forecast to exit the area around 21Z, then a second
wave moves into the SE for the evening. There will also be surface
convergence in the SE. HRRR had some spots of 500-1000 j/kg CAPE
into the evening in the SE, and SREF had Effective Bulk shear
greater than 30 kt in this area. HREF had helicity tracks confined
to NE WY. The second wave will move into the unstable airmass
this evening bringing isolated to scattered showers and
thunderstorms to SE MT and Sheridan County, WY through 06Z. The
wave moves quickly out of the area after 06Z for a dry overnight.
On Wednesday, region continues under cyclonic flow with vorticity
moving through the flow. While precipitable waters will not be
that low, GFS soundings looked very dry, so left PoPs out for now.
Later shifts can add low PoPs if needed. Winds looked similar to
today`s winds on the EC Ensembles, and NBM reflected this well.
Temps will be a few degrees warmer on Wednesday. RH`s will be
mostly in the teens again. Fuels are still gradually drying out. A
flat NW flow will be over the area Wed. night for a dry night.
Thursday through Tuesday...
Warm and dry conditions are expected Thursday as a modest ridge
of high pressure builds over the region. Highs Thursday will be
mainly in the 90s. Friday may even be a bit warmer as we get some
pre-frontal warming ahead of a weak cold front that moves across
the area in the evening. The frontal passage may produce some
showers or isolated thunderstorms, especially over the eastern
plains, but does not have much low level moisture to work with so
we are not expecting much precipitation Friday evening.
Another frontal passage is progged by the models Saturday as a
reinforcing shot of energy tracks across southern Canada to our
north. This has some pressure rises behind it that suggest a brisk
N/NW wind over our CWA Saturday. Highs will be about 5 to 10
degrees cooler Saturday. Low level winds turn easterly by Saturday
evening increasing the chance of showers and thunderstorms over
the area. By Sunday, an unstable NW flow over easterly surface
winds will result in some scattered showers and thunderstorms,
mainly over the eastern plains. Highs Sunday will be below average
in the mid 70s to lower 80s.
Unsettled conditions, mainly in the east, continue into next week
under that NW flow. Afternoon highs will slowly moderate into the
80s. BT
&&
.AVIATION...
VFR will prevail through Wednesday. borsum
&&
.PRELIMINARY POINT TEMP/POPS...
Wed Thu Fri Sat Sun Mon Tue
-----------------------------------------------------------
BIL 051/085 056/093 062/094 061/086 059/080 057/082 058/086
00/U 00/U 01/U 22/T 45/T 32/T 22/T
LVM 044/084 049/090 055/091 053/085 051/080 049/083 051/085
00/U 00/U 02/T 22/T 33/T 22/T 12/T
HDN 049/087 054/095 060/097 060/088 058/082 056/083 057/088
00/U 00/U 00/U 21/B 44/T 32/T 22/T
MLS 051/084 056/092 064/095 063/086 059/079 056/081 058/085
00/U 00/U 00/U 21/B 54/T 32/T 22/T
4BQ 052/085 056/091 063/096 061/089 059/080 055/081 056/087
10/U 00/U 00/U 21/U 55/T 33/T 32/T
BHK 050/083 053/089 061/094 060/085 056/079 053/080 055/084
00/U 00/U 01/U 21/U 55/T 32/T 32/T
SHR 049/086 053/093 060/098 058/089 056/082 053/083 054/088
10/U 00/U 01/U 22/T 55/T 43/T 32/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
656 PM CDT Tue Jul 14 2020
.SHORT TERM...(This evening through Wednesday)
Issued at 306 PM CDT Tue Jul 14 2020
The cold front has moved through the area, and temperatures have
either leveled off or even started to fall due to the cold air
advection and increased cloud cover. A few light showers are
percolating west and southwest of the forecast area. The HRRR
shows these sticking around through the evening, but impacts will
likely be minimal.
Tonight, another round of thunderstorms is expected to develop,
mainly over the southeastern half of the forecast area. This is in
response to a compact perturbation rounding the trough and an
increasing upper level jet aloft. Main low-level jet forcing will
remain southeast of the area, but there still may be enough
residual instability behind the front for some marginally severe
storms with hail being the main threat. In addition, PWAT values
over 2.0 and some relatively slow storm motions may lead to
locally excessive rainfall. Even so, soils are not saturated, and
most locations could easily take 1-2 inches or even more.
Wednesday is setup to be a very nice day. Skies should clear by
mid to late morning, and winds should remain fairly light as high
pressure slides by to our east. Highs are forecast to be around 80
degrees, which is actually much closer to our normal temperatures
for early September than for mid July!
.LONG TERM...(Wednesday night through Tuesday)
Issued at 306 PM CDT Tue Jul 14 2020
We will start to see return flow on Thursday, which should push
temperatures back closer to normal. Returning moisture will also
bring us at least some chance for thunderstorms Thursday night.
For now, it doesn`t look like a major severe threat, but it we
cannot completely rule out a severe storm or two.
The heat really builds into the area Friday through the weekend.
Saturday is still anticipated to be the hottest day of the
stretch, with highs ranging from 96 to 102 degrees. Many
locations, particularly in eastern areas, will see heat index
values of 105 degrees or more.
Increased ridging and rising temperatures aloft should keep us
effectively capped through Saturday, but chances for thunderstorms
return Sunday into Monday as a trough pushes another front into
the area.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 650 PM CDT Tue Jul 14 2020
A cool light northeast breeze is expected to continue throughout
the TAF valid period. Clouds will likely be around the area
through Wednesday morning with clearing skies Wednesday
afternoon. Expect ceilings for the most part should remain above
3000 ft agl.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Key West FL
1054 PM EDT Tue Jul 14 2020
.DISCUSSION...
The main weather story will be a transition from the ongoing
below normal rain chances to above normal rain chances by
Thursday. Over the waters, easterly breezes will develop early
Wednesday and freshen to a moderate breeze by late Thursday.
A 500 mb subtropical ridge axis has been over or near the Keys in
recent days. The ridge will move north and re-develop in a large
swath from the Southern Plains across the Southeast States to near
Bermuda. Deep low-latitude easterly flow will therefore expand
northward to encompass the Keys. Of course, this will open the
door to all of those things that come in long-fetch easterly flow,
such as deeper moisture and undulations in the easterly flow. For
example, our PW values will rise from current values near the 25th
percentile into the 75th to 90th percentile range by Thursday,
then remain there well into next week. The first broad inverted
trough axis will pass westward across the Keys on Friday. All of
this points to increasing rain chances over the next 2 days, with
above climo rain chances from Thursday through early next week.
In the meantime, our current weather is quiet, with an echo-free
radar locally. The 00z KEY sounding revealed a weak subsidence
inversion near 2,500 feet, which effectively shut down our precip
today. This is expected to dissipate overnight. The leading edge
of our developing easterly flow should traverse the forecast
domain on Wed morning, possibly providing some weak focus for a
few showers or thunderstorms on Wed morning. The last several HRRR
runs have been trying to develop a few showers around the Lower
Keys just after sunrise. There is only loose consensus around
this idea, but it fits in with the greater trend toward increasing
convective coverage over the next 2 days.
&&
.MARINE...
Over the next 48 hours, winds will become more decidedly easterly
on Wednesday, then freshen to moderate breezes late Thursday.
Otherwise, look for increasing shower and thunderstorm coverage
through Thursday, with thunderstorm-related impacts becoming the
main concern for mariners from Thursday through Saturday.
From synopsis...A ridge axis stretching west through the Straits
of Florida this evening will lift northward to Central Florida by
late Wednesday. The ridge will continue north to North Florida and
Georgia on Thursday, where it will remain through the weekend. As
the Keys come under the southern periphery of the ridge, our
light and gentle breezes will freshen and become moderate breezes
starting Thursday evening.
&&
.AVIATION...
Some of the latest models are pointing to development of a few
showers in the vicinity of the Lower Keys soon after sunrise on
Wed morning. This may require insertion of VCSH into the EYW
and/or MTH TAF for the late morning hours. Otherwise, VFR
conditions will prevail, and winds will become easterly by sunrise
Wed.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...Haner
Aviation/Nowcasts....Haner
Data Acquisition.....Chesser
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Area Forecast Discussion
National Weather Service Marquette MI
757 PM EDT Tue Jul 14 2020
.SHORT TERM...(This evening through Wednesday)
Issued at 440 PM EDT TUE JUL 14 2020
WV imagery and RAP analysis indicated a mid/upper level low over
northern Manitoba with a broad trough extending into the northern
Plains resulting in southwest flow into Upper Michigan. At the
surface, a cold front extended from the MN arrowhead through western
WI. One shrtwv and associated MCS was sliding ene from ne WI and
central Upper Michigan. Additional showers and isold thunderstorms
from western Lake Superior through northwest WI were supported by
850-700 mb fgen and low level conv near the cold front.
Tonight, radar trends and short range models/CAMs suggest that the
shra/tsra with the front will expand through the west half of Upper
Michigan before 00z and then to spread through central Upper
Michigan during the rest of the evening from 00z-06z and over the
rest of the east half overnight. With little MLCAPE and MUCAPE
values only into the 500-1000 J/Kg range, strong/severe storms are
not expected. However, with PWAT values to around 1.75 inches, and
showers moving parallel to the slow moving front, some locally heavy
rain may still be possible with any stronger cells. By late tonight,
drier air will advance through the west half with some clearing
skies.
Wednesday, some -shra may linger over the far south and east as the
front only slowly sags to the southeast. Another shrtwv lifting
toward WI during the afternoon may spread additional light rain into
the far south and east. With the instability well to the south, only
light rain would be expected. Otherwise, partly to mostly sunny
skies over the rest of the area may cloud up a bit during the
afternoon. Highs should climb to near seasonal averages with
readings in the mid to upper 70s and possibly to around 80 over the
northwest. It will also be more comfortable with dewpoints dropping
into the upper 40s to mid 50s.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 112 PM EDT TUE JUL 14 2020
Global deterministic and ensemble models show surprisingly good
agreement in terms of the overall hemispheric conditions through the
next 7 to 10 days. Even the CFS has been showing a consistent
pattern on a run to run basis as seen on both dprog/dt and suggested
on its 6-run, time-lagged ensemble. Suppose it then is no surprise
to see the confidence in CPC`s latest 6-10 and 10-14 day forecasts
calling for increased chances of above normal temperatures for much
of the CONUS, and even leading into the 3 to 4 week fcst. Mean
troughing will persist through Thursday before ridging begins to
build in from the west and heights rise Friday. Behind this ridging,
more zonal flow will take hold through the weekend for a cold front
and broad troughing pushes into the central CONUS. So aside from any
lingering showers and thunderstorms across the far east Wednesday
night, our next chance of any mentionable precipitation will be tied
to the cold front progged for Saturday night into Sunday.
Temperatures will then be near to perhaps slightly blo normal
briefly on Monday & Tuesday next week before signs for a return to
normal/slightly above normal return mid-week.
Wednesday night into Thursday, mean troughing is across the central
CONUS with the remnants of this evening/tomorrow`s cold front and
associated precip off to the east of the UP. As a weak sfc low rides
NE along this trough, high pressure will also be riding along the
base of the trough. The pressure gradient increases some as a wave
in Canada shifts east; with SW winds carrying in a warmer air mass,
high temperatures climb back up to about 5 to 10 degrees abv normal.
Those in the SW downslope-favored areas could see some upper 80s,
with widespread 80s expected elsewhere.
Friday will be similar to Thursday, though perhaps a little more
humid and warmer as heights rise and the column as a whole becomes
warmer. With more SW winds, downsloping into Marquette and along
Lake Superior may actually feel warmer than some of the highlands.
By Saturday, upper-level pattern becomes a bit more zonal, but
various MOS guidance and deterministic models have continued to
show this being the warmest day of the week for the last several
days worth of model runs. With continued WAA at 850mb Thursday into
Friday, models suggest 850mb temps near 20C on Saturday.
As another wave passes to the north across Canada, a weak cold front
is progged to pass through Upper Michigan Saturday into Sunday. Fcst
is rather broad brushed at this point yet to acct for temporal
differences and models are suggesting two separate waves of precip,
but maintain chance PoPs Saturday afternoon through Sunday.
The first chance of precipitation comes along the passing of the sfc
trough. The second looks to be in response to the fgen forcing under
the right entrance region of a passing 100kt jet. Behind this cold
front, models show decent consensus on temps falling to near-normal
or perhaps slightly blow normal through Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 741 PM EDT TUE JUL 14 2020
Numerous showers along a cold front moving through the area will
bring IFR conditions to KSAW this evening before showers taper
off late evening with a gradual improvement to MVFR. Conditions
at KSAW will continue to improve to VFR overnight as drier air in
the wake of the cold fropa works its way in from the west.
Despite showers moving east of KCMX, onshore westerly flow will
continue IFR to LIFR conditions there early this evening before
improvement to MVFR by late evening and VFR overnight as drier air
works in behind the front. Expect VFR conditions at KIWD through
the forecast period.
&&
.MARINE...
Breezy conditions are expected into this evening over the east half
with southerly winds to 25 knots. A front will move across the area
from west to east tonight into Wednesday, winds behind the front
will shift sw to w at 10 to 15 knots. Winds look to remain
southwesterly and mainly below 15 kts through Friday, with the
exception of the west where sw winds will gust to 20 knots on
Thursday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...JAW
AVIATION...Voss
MARINE...JLB
Area Forecast Discussion
National Weather Service Paducah KY
302 PM CDT Tue Jul 14 2020
.SHORT TERM...(Tonight through Wednesday night)
Issued at 259 PM CDT Tue Jul 14 2020
Surface high pressure has resulted in a seasonable summer day with
temperatures ranging from the mid 80s to around 90 at 2 PM under
mostly sunny skies. Lower humidity levels have also migrated across
our entire cwa, providing a short reprieve from the oppressiveness.
The main challenges over the next 36 hours will reside with
increasing heat and humidity levels on Wednesday, along with the
potential for severe thunderstorms, primarily focused on Wednesday
evening.
Warm air advection showers and thunderstorms are possible late
tonight into Wednesday morning across portions of southeast Missouri
and southwest Illinois. Aside from this activity, much of the day on
Wednesday looks to be dry. However, models do vary on timing of
possible convection later in the day/evening. The 12z GFS is one of
the fast outliers, with convection moving into the northwest between
21-00z. The 12z HRRR was a bit more aggressive on the faster timing
as well. The consensus amongst synoptic models and CAMs was for a
later arrival though, moving into our far northwest sometime in the
00-04z time range. There is also some guidance, like the 12z ECMWF,
that indicate the majority of the convection remains north of our
area.
We tend to agree with the placement of the SPC Day 2 slight and
marginal risks across our northern counties. Plentiful instability
and moisture look to be present with sfc CAPEs possibly exceeding
5000 J/kg and dewpoints pooling into the mid 70s, and possibly
locally higher. The best dynamics and shear look to remain north of
our cwa, but 30-35 knots of deep layer shear may still be realized
across our far northern counties. The greatest threat from any
severe storms would probably end up being damaging winds.
Another concern will be torrential rainfall that could lead to some
localized flooding issues. Precipitable water values may approach
2.4 inches tomorrow evening, with very efficient rainfall occurring
with any storms.
Temperatures on Wednesday look to warm into the mid 90s in many
locations. Higher humidity levels will return to the western half of
the region, which will result in heat index values of 100 to 105,
and possibly locally higher. Somewhat lower values in the upper 90s
are expected across the Evansville Tri-state region and Pennyrile of
west KY. For now will issue an SPS, and defer to the midnight shift
to determine if a Heat Advisory may need to be issued for portions
of southeast Missouri.
.LONG TERM...(Thursday through Tuesday)
Issued at 259 PM CDT Tue Jul 14 2020
Models bring a frontal boundary southeast late in the week,
gradually sinking into the PAH forecast area for Friday and the
weekend while gradually washing out. This results in good chances
of showers and storms Thursday into Friday. Due to the weakening of
the front, showers and thunderstorm chances become more diurnal for
the weekend. Any convection Saturday should be mainly along and
east of the Mississippi River, and Sunday and Monday from
southwest Indiana into the Pennyrile region of west Kentucky.
Chances increase Tuesday and spread back to the west with the
approach of another cold front.
Throughout the extended, heat and humidity will remain a concern.
Persistent southerly flow will continue to bring warm moist air into
our region. Dew points will primarily be in the lower to middle
70s, and these values will also be our overnight lows. Highs will
be in the lower to middle 90s Thursday and Friday, and in the middle
90s over the weekend into early next week. This will give us heat
indices from around 100 to around 105 degrees.
&&
.AVIATION...
Issued at 1211 PM CDT Tue Jul 14 2020
VFR conditions expected through this TAF period. Winds will be
light out of the southeast today, before becoming southerly and
increasing into the 7-10 kt range by late morning tomorrow.
Few/scattered cu field this afternoon will dissipate with sunset,
with high clouds on the increase overnight into tomorrow morning.
Small chance for isolated convection late tonight into tomorrow
morning, primarily in southeast Missouri and southwest Illinois.
Confidence too low to include mention in KCGI terminal at this
time though.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
SHORT TERM...SP
LONG TERM...RST
AVIATION...SP