Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/28/19
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
514 PM MDT Fri Sep 27 2019
.AVIATION...
00Z TAF CYCLE
Weakening upper low over sw NM at 23Z will continue to track to the
ne-e over NM as it opens into a trough. Isold to wdly sct convection
associated with this feature south of Interstate 40 at 23Z is
indicated by short term models to persist, possily becoming sct over
south central and sern NM aft 02Z, where an isold strong to severe
storm is possible. Meanwhile, a few light showers may develop as far
north as KABQ. Clearing from west to east is expected by 28/12Z,
although isold-lcl MVFR cigs possible 28/09-15Z in the KGUP area,
from KRTN-KCAO associated with a weak surface boundary and from the
KCVN vcnty swd due to moist low level sly flow.
&&
.PREV DISCUSSION...319 PM MDT Fri Sep 27 2019...
.SYNOPSIS...
A weak weather system moving slowly east through southern New Mexico
today will spark off a few showers and thunderstorms south of I-40
through this evening. A couple of these storms may become strong
over southeast New Mexico where large hail, damaging winds, and
locally heavy rainfall are possible. Southwest winds will increase
over the weekend with the strongest winds expected on Sunday. High
temperatures will also warm above normal again for the entire area. A
potentially significant rainfall event may develop over eastern New
Mexico late Sunday through Tuesday as deep moisture surges north into
the area. Temperatures will begin cooling closer to normal for the
entire area by the middle of next week.
&&
.DISCUSSION...
The recent extended stretch of mainly tranquil weather will come to
an end over the weekend as a significant pattern change develops
over North America.
First, the upper level low that parked over AZ for the past several
days is ejecting slowly eastward into southern NM today. 19Z LAPS
and satellite analysis indicate moisture and instability is slowly
increasing eastward south of I-40. The updated SPC outlook from this
morning increased the marginal threat for severe storms from the
southern deserts eastward across southeast NM this evening. The 12Z
HREF and latest RAP guidance are certainly on board with convection
advancing northeastward through the southeast plains. This latest
forecast leans toward the higher NBM PoPs due to higher confidence.
Any storms that impact the southeast will be capable of localized
large hail, damaging winds, and heavy rainfall.
A weak back door cold front will then sag southwest into northeast NM
tonight in the wake of the departing upper wave. An area of low cigs
is expected to develop along the CO border from near Raton eastward
to Clayton.
The aforementioned pattern change will take shape over the weekend
as an unseasonably strong high amplitude wave pattern develops over
North America. 700-500mb layer south-southwest flow will increase to
near 30 kt on Saturday then become more southwest on Sunday while
increasing to near 45 kt. A strengthening surface pressure gradient
through this period will result in widespread breezy winds Saturday
then widespread windy conditions on Sunday. Wind advisories are now
looking more likely over parts of the west and northeast plains for
Sunday.
The potentially more significant aspect of the pattern change will be
a remarkable +4 stdev moisture plume advecting northward into NM late
Sunday through Tuesday. Medium range model guidance continues to show
an area of 1-3" rainfall amounts extending over southeast NM during
this period, followed by yet another wave of heavy rainfall by mid to
late week. This second wave of precip is much more in question but
has potential to impact areas farther west into the Rio Grande Valley
by late next week.
Guyer
&&
.FIRE WEATHER...
Breezy to windy conditions will expand over the forecast area this
weekend with the strongest winds expected on Sunday. Winds may even
reach Wind Advisory criteria in the northeast on Sunday. Even with
dry conditions for most this weekend, minimum humidity values are
currently forecast to stay just above critical thresholds. Still, a
couple hours of localized critical fire weather conditions can`t be
ruled out on Sunday for central and northeastern NM. Meanwhile,
chances for wetting precipitation will rise for southeast and east
central NM this weekend as moisture surges in from the south. With
an unstable atmosphere, a few severe thunderstorms will also be
possible in this area this weekend. Monday and Tuesday will likely
feature the best chances for widespread wetting rainfall for the
east as deeper moisture surges northward. Chances for rain will
expand westward into central and western NM late next week as
moisture seeps into the Rio Grande Valley.
15
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Birmingham AL
717 PM CDT Fri Sep 27 2019
.UPDATE...
For 00Z Aviation.
&&
.SHORT TERM...
/Updated at 0419 PM CDT Fri Sep 27 2019/
Tonight and Tomorrow.
As easily felt outside this afternoon, temperatures achieved their
advertised above average values with many places reaching the mid to
upper 90s once again. This has been a trend for an extended period
with expectation it continues well into next week. Unfortunately
this adds to our worsening drought situation, as well as keeping
elevated fire weather conditions in play throughout the next
several days as soil moisture continues to deplete.
For today, southerly flow across Central Alabama has accompanied
widespread afternoon cumulus development, with isolated showers &
thunderstorms in some local areas. Thus far, moisture quality and
convective activity have favored the southeast where PWs have
increased as high as ~1.9" per latest RAP mesoanalysis. Thus,
adjusted PoPs from current observations with a downward trend
through the evening. The only mentionable forecast change for this
evening is inclusion of isolated activity a few hours later as
locally heavier activity may linger a bit after dark. Otherwise,
overnight temperatures in the upper 60s & lower 70s remain in place
with clear & calm weather overall.
For tomorrow, PoPs have been increased in the east where latest
guidance suggests more favorable moisture convergence within the
zone of higher PWs (1.8-1.9"), particularly east of I-65. Despite a
relatively subsident atmosphere within the amplifying deep-layer
ridge, thunderstorms have managed to take advantage of afternoon
moisture/instability, where available, as convective temperatures
are reached. Will also evaluate the morning RAOB as dry air aloft &
the overall environment may favor a few strong wind gusts in any
robust thunderstorm activity, though this remains low confidence
as a whole. High temperatures in the mid to upper 90s should be
expected once again, outside of any areas lucky enough to receive
rain. No other major changes were made to the below discussed
long-term forecast.
40/Sizemore
.LONG TERM...
/Updated at 0306 AM CDT Fri Sep 27 2019/
Through Friday.
Potential for record high temperatures continues through Thursday.
The ridge continues to build across much of the Eastern CONUS on
Sunday as a strong upper level low digs into the Pacific NW. For
Central AL, this will mean continued dry and hot weather. High
temps are expected to run in the mid to upper 90s each day through
at least Thursday. Some guidance suggests a cold front could
approach towards the end of next week, but that remains uncertain
as models continue to disagree on if/how quickly the ridge breaks
down. Given how anomalous the current pattern is, I`m hedging the
forecast against a quick breakdown of the ridge, which might be
influenced by a bias towards climatology in the extended.
Therefore, the forecast will be for warmer and drier weather to
continue through Friday. See the climate section below for the
high temperature records.
25/Owen
&&
.AVIATION...
00Z TAF Discussion.
There are still some TSRA around in the eastern half of C AL at
this time. I have VCSH mentioned for BHM/ASN/ANB for an hour. The
activity should start deteriorating now that we have lost daytime
heating. Otherwise, VFR conditions are expected through the
period. Isolated TSRA is possible again the eastern portions of C
AL again on Saturday afternoon, but is too low to mention at any
of the terminals at this point.
08
&&
.FIRE WEATHER...
Central Alabama will experience mostly dry and hot conditions
through the end of next week. Afternoon relative humidity values
will generally fall into the 30 percent range each afternoon.
These low humidity values and high KBDI values will result in a
continued elevated fire danger. Light winds are expected to keep
us below red flag conditions. Fair weather will dominate, though a
few spotty showers or isolated thunderstorms will be possible
across portions of Central Alabama this afternoon.
The Alabama Forestry Commission has issued a fire alert that
includes all of Central Alabama. For more information about
restrictions, visit their web site at forestry.alabama.gov.
&&
.CLIMATE...
Record high temperatures:
Today 9/27:
Birmingham: 94 (1998, 1898, 1897)
Montgomery: 96 (1954)
Tuscaloosa: 97 (1954)
Anniston: 97 (1954)
Saturday 9/28:
Birmingham: 94 (1986, 1911, 1904)
Montgomery: 96 (1986)
Tuscaloosa: 96 (1986, 1954)
Anniston: 95 (1954)
Sunday 9/29:
Birmingham: 96 (1904)
Montgomery: 96 (1904)
Tuscaloosa: 96 (1986)
Anniston: 95 (1904)
Monday 9/30:
Birmingham: 95 (1904)
Montgomery: 97 (1904)
Tuscaloosa: 96 (1954)
Anniston: 94 (1904)
Tuesday 10/1:
Birmingham: 94 (1919)
Montgomery: 95 (1954)
Tuscaloosa: 95 (1954)
Anniston: 93 (1954)
Wednesday 10/2:
Birmingham: 93 (1904)
Montgomery: 95 (1904)
Tuscaloosa: 95 (1954)
Anniston: 93 (1954)
Thursday 10/3:
Birmingham: 93 (1911)
Montgomery: 94 (1959)
Tuscaloosa: 95 (1954)
Anniston: 92 (1954)
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 69 95 68 97 69 / 20 20 20 10 0
Anniston 70 95 69 97 69 / 20 30 20 10 0
Birmingham 72 96 73 97 72 / 20 20 10 10 0
Tuscaloosa 70 97 72 98 72 / 10 10 0 0 0
Calera 70 98 70 99 69 / 20 20 10 0 0
Auburn 71 94 69 94 69 / 20 20 10 0 0
Montgomery 72 98 71 100 70 / 20 20 10 0 0
Troy 71 96 69 97 69 / 20 20 10 0 0
&&
.BMX WATCHES/WARNINGS/ADVISORIES/...
None.
&&
$$
40/25/08
Area Forecast Discussion
National Weather Service Grand Junction CO
447 PM MDT Fri Sep 27 2019
.SHORT TERM...(Tonight through Saturday night)
Issued at 317 PM MDT Fri Sep 27 2019
Models initialized well today and continue to perform well with
the placement of the current convection. PWATs from this morning`s
sounding at Grand Junction was at .65 inches which is about 150%
of normal so there is some available moisture for disturbances to
work with. And work with them they are, as a weak disturbance is
just clipping northern portions of our CWA while daytime heating
and moisture and modest instability allow convection to form over
the higher terrain. The biggest concern will be gusty winds this
afternoon as convection taps into some stronger winds aloft. Gusts
this afternoon have ranged in the 30 to 40 mph range north of
I-70 and this trend will continue though some higher gusts under
the convection is possible. Of note, the HRRR has been showing
another weak disturbance moving through the area from mid-evening
onwards generally north and along the I-70 corridor. If this pans
out, the convection could continue for much of the overnight.
Forecast follows suit though only slight chances for now. Later
shifts can evaluate and modify as necessary.
The big news continues to be the wind on Saturday as the next
system drops down from the Pacific Northwest. This is the system
that is expected to bring feet of snow to parts of Montana. For
our neck of the woods, the upper level support for the system will
slowly start moving into our area. The support is in the form of a
100kt jet that will strengthen over time. In addition to the jet,
the surface pressure gradient will also tighten as the low gets
closer to the area. This all means that we`ll see some winds on
Saturday in a swath from east-central Utah up into northwestern
Colorado. Gusts will reach 45 mph at times at the surface and
possibly near 60 mph over Douglas Pass which has warranted a wind
advisory for those areas tomorrow afternoon from noon through
9PM. The strongest winds are expected from 3PM through 6PM. A few
showers and storms are also possible tomorrow afternoon but models
have really pulled back on coverage and intensity for the area and
shifted it to Idaho and Wyoming. Outside of the odd shower or
storm, most areas will see partly cloudy skies, warm temperatures
thanks to southwesterly flow and breezy conditions...more so for
those areas in the advised areas.
.LONG TERM...(Sunday through Friday)
Issued at 317 PM MDT Fri Sep 27 2019
More of the same on Sunday but it`ll be even windier. The low
pressure will remain to our northwest but by this time, the jet
stream will be blowing at 125 kts and will be directly overhead.
Doesn`t look like there`ll be much in the way of clouds so nothing
will inhibit deep mixing and with forecast soundings showing 50kt
winds at 700mb, or 10,000 feet, we can expect a windy day, indeed. Any
mixing will bring these winds to the surface. There`s a chance
that some high wind warnings might be necessary for Sunday and if
not warnings, certainly advisories. A few more model runs, and how
windy we get on Saturday, will help with future forecasts. A few
more showers and storms are possible mainly over the eastern
Uintas and, to a lesser extent, the San Juans but again, the best
precip will stay to our north.
By Monday, the area of low pressure will have moved into Canada but
the trough will remain to our west and the jet stream still stays
overhead. Yep, another windy day expected though winds should be
a less than those seen on Sunday. Dry conditions then set up with
warm temperatures continuing until Wednesday when the upper level
trough finally moves through. This trough passage will swing the
winds back to the northwest bringing in some cooler air and
dropping daytime highs several degrees. Dry conditions persist
through the end of the week into the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 443 PM MDT Fri Sep 27 2019
Gusty winds will continue this evening. Isolated showers and
thunderstorms will continue over the mountains will the most and
stronger storms north of Interstate 70. VFR conditions will
prevail at all TAF sites for the next 24 hours, due to spotty
storm coverage.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Wind Advisory from noon to 9 PM MDT Saturday for COZ001>003.
UT...Wind Advisory from noon to 9 PM MDT Saturday for UTZ024-025-027.
&&
$$
SHORT TERM...TGR
LONG TERM...TGR
AVIATION...CC
Area Forecast Discussion
National Weather Service Grand Rapids MI
940 PM EDT Fri Sep 27 2019
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 257 PM EDT Fri Sep 27 2019
- Heavy rain this evening across southern Lower Michigan
- Low chances for rain linger into next week
&&
.UPDATE...
Issued at 930 PM EDT Fri Sep 27 2019
Bands of heavy rain and convection will continue to develop
through the late evening hours as a result of elevated instability
and forcing from both the approaching cold front and llj.
Isolated strong to marginally severe storms with hail cannot be
completely ruled out given the elevated instability. However
greater concerns continue to involve heavy rain and potential for
mostly localized urban and small stream type flooding issues.
Strong 1000-850 mb moisture transport as well as KGRR/rgnl radar
trends continue to show potential for some localized flooding.
Rgnl radar trends and latest runs of the HRRR suggest that the
highest end rainfall amounts will most likely occur just south of
our fcst area across extreme southern lower MI and northern IN
(although it will be very close call for the I-94 corridor).
Nevertheless widespread rainfall amounts of an inch or two are
expected across roughly the southern half of our fcst area.
Locally higher amounts are certainly possible where training of
echoes is most persistent. This could cause some mainly urban and
small stream type flooding issues. Our going forecast looks pretty
good with only minor fcst tweaks necessary.
&&
.DISCUSSION...(This evening through next Friday)
Issued at 258 PM EDT Fri Sep 27 2019
Rain amounts for tonight continue to be the forecast issue as
various model solutions show a lull between the current batch of
storms and a second area of convection forming over northern
Illinois this evening and reaching into the southern half of Lower
Michigan. We have adjusted QPF a bit further south with storm
totals around 1.5 inches or more south of Grand Rapids and
Lansing. This would include what falls this afternoon.
The severe weather threat is low since the storms are elevated but
we have seen winds gusting to over 50 mph near Lake Michigan on
the backside of the convection, so there could be a period of
strong winds in a wake low set up.
Once the second batch of storms goes through tonight we expect
improving conditions with only slight or low chances of rain over
the rest of the weekend. Convection could form along a warm front
on Sunday night or Monday morning, so this will have to be
monitored. That warm front comes back south on Tuesday and
Wednesday so more storms are possible then.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 815 PM EDT Fri Sep 27 2019
There is currently active convection over most of our TAF sites
and there is additional storms upstream to west of CHI that will
have move through our TAF sites this evening. It would seem the
heaviest storms will be in the 03z to 06z time frame. Expect IFR
cigs/vsby in the stronger storms and gusty winds.
There is a large area of low clouds (IFR) cigs just north of I-96
that will move south across the all of the TAF sites after 06z
behind the rain and thunderstorms. The low clouds will clear out
by mid to late afternoon.
&&
.MARINE...
Issued at 815 PM EDT Fri Sep 27 2019
Since winds have diminished we have replaced the gale warning
with Small Craft Advisory that will continue it Saturday
afternoon.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 10 PM EDT Saturday for LMZ844>849.
&&
$$
UPDATE...Laurens
SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
958 PM EDT Fri Sep 27 2019
.SYNOPSIS...
A weak cold front will move southeast into the Great Lakes
tonight, then south across the Ohio Valley region Saturday into
Saturday night. A chance of showers and thunderstorms will be
possible along and ahead of the front. High pressure will build
back into the region through the first half of next week. This
will lead to dry conditions and well above normal temperatures
through mid week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Storms in northeastern Indiana produced an outflow boundary
late this afternoon, which proceeded to progress across a
fairly healthy chunk of the ILN forecast area over the next
several hours. The air mass over the ILN CWA was not
particularly favorable for convection, but a region of greater
boundary layer moisture had advected northward along the IN/OH
border, and provided just enough instability to allow the
outflow to spark off a series of showers and storms. This
activity has dissipated with the loss of diurnal heating,
leaving dry conditions for a while. The next chance for
precipitation appears to be across the central and eastern
sections of the CWA in the 08Z-14Z time frame, with consistent
signals from the HRRR and NAM that a shortwave will combine with
increasing moisture near and just above the boundary layer to
bring storm development. PoPs were increased slightly for this
activity, especially along and east of US-23 around 12Z.
Based on current trends, some slight upward adjustments were
made to min temps.
Previous discussion >
Have issued an SPS for our northern/eastern zones through early
evening where warm temperatures, low dewpoints/low RHs, gusty
winds, and dry small fuels have brought a short term enhanced
fire danger.
Otherwise, will continue to watch convection to our northwest
per mosaic radar. Convection should make west central Ohio by
late afternoon or early evening before falling apart during the
evening hours. Have a chance of showers/storms there. Otherwise,
some debris clouds will overspread the north while the south
remains mostly clear.
For the overnight hours, a cold front will continue to move
southeast into the Great Lakes. Embedded s/wv energy and a low
level jet will bring renewed convection along and ahead of the
front. CAMs suggest that some of this convection, perhaps
generated by an outflow boundary, may propagate or develop
across our north late. For our southern zones, it will remain
mostly clear for a good part of the night. Then, models indicate
broad but weak, moist ascent in the 925 mb-850 mb range
(associated with a weak mid level s/wv) which should allow
skies to become partly cloudy. Elevated instability may also
result in a low chance of a shower or storm, especially across
south central Ohio and northeast Kentucky. Overnight lows will
range from the lower to upper 60s.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Any convection ongoing in the east should wane or move east
during the morning with a brief reprieve in the pcpn threat.
Then, aforementioned cold front will make its way south into our
northern zones during the afternoon. Stronger dynamics will
remain to our north, but some moderate instability and weak low
low level convergence will bring a chance of showers and
thunderstorms to the north. SPC just skims our far east with a
marginal risk for severe storms. This is due to moderate
instability overlapping with some moderate shear. Coverage is
too small to mention in the HWO at this time. Southern locations
should remain dry on Saturday. It will be another very warm to
hot day, especially south where the front will not have moved
through. Highs will range from the lower 80s far northwest, to
the lower 90s along and south of the Ohio River. A record high
could be threaten at KCVG.
For Saturday night, convection should wane during the evening
as the front slowly sags south toward the Ohio River. An
upstream s/wv and a low level jet may bring renewed convection
to our west/northwest overnight, but it is unclear if this will
make it into our area. Have gone dry with skies ranging from
partly to mostly cloudy. Lows will range from the lower to the
upper 60s.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
he extended period begins with a front stalled over the region. The
NAM and GFS are taking an H5 s/w across Ohio on the northern edge of
the upper ridge which is producing some scattered convection. The
ECMWF and CMC keep any precipitation northwest of the area. Leaned
towards the drier forecast, since we have had a hard time getting
rainfall lately. Highs Sunday will range from the lower 80s in the
far northwest to around 90 in nrn KY.
The H5 ridge will continue to expand northward during the first part
of next week, with the center of the ridge reaching the Tennessee
Valley by Tuesday. This will bring dry weather and unseasonably hot
temperatures. Forecast highs Monday will be in the upper 80s to the
lower 90s Monday and lower 90s Tuesday. These readings will be 15 to
20 degrees above normal and could set records Tuesday.
Forecast for Wednesday has changed a little. Models now are quicker
in bringing a cold front into the region. The consensus is that it
will have reached the northern counties by 00Z Thursday. This might
bring isolated convection into the north. Highs will still be much
above normal, ranging from upper 80s in the north to the lower 90s
south.
The front continues to push south Wednesday night into Thursday.
This will bring lower temperatures and chance PoPs. Highs will range
from the lower 70s in the far northwest to the lower 80s in the
southeast.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
While generally quiet conditions are expected at the TAF sites
through the forecast period, convection cannot be completely
ruled out at several times in the next 24 hours. Storms over
northern Indiana / northwest Ohio have been building southward
this evening, but it is not expected that they will make it into
the Dayton / Columbus airports as of now. Later in the overnight
and early Saturday morning, there is a slightly greater chance
for scattered showers and storms to develop near the Dayton /
Wilmington / Columbus airports. A VCSH has been included here.
Cincinnati is less likely to be affected.
Outside of any possible precipitation, tracking wind shifts will
be the only real concern to watch in the TAFs. Gusty winds this
afternoon have diminished, and will remain out of the SSW
through the overnight hours in the 5-10 knot range. These winds
will increase slightly tomorrow out of the SW, before a cold
front moves into the area tomorrow night. This front will
eventually shift winds to the NE, with a period of light and
variable winds before it arrives. This looks like it will occur
just beyond the end of the current forecast period.
There may also be some low level wind shear overnight in
northern Indiana and northwest Ohio, but right now it does not
appear it will be strong enough to include in the TAFs.
OUTLOOK...No significant weather is expected.
&&
.CLIMATE...
Anomalously strong mid level ridge over the area late this weekend
into next week. H5 heights look to be 1.5 to 2 standard deviations
above normal. Temperatures are forecast to be 15 to 20 degrees above
normal with temperatures approaching records next Monday,Tuesday and
Wednesday.
Records...
SEP 30th
CVG 92...year 1941 & 1953
DAY 94...year 1897
CMH 92...year 1953
OCT 1st
CVG 88...year 1897, 1919 & 1927
DAY 93...year 1897
CMH 89...year 1952
OCT 2nd
CVG 90...year 1919
DAY 90...year 1898 & 1900
CMH 88...year 1919
OCT 3rd
CVG 89...year 1910 & 1919
DAY 93...year 1900
CMH 89...year 1898 & 1953
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Hickman
NEAR TERM...Hatzos/Hickman
SHORT TERM...Hickman
LONG TERM...Sites
AVIATION...Hatzos
CLIMATE...
Area Forecast Discussion
National Weather Service Northern Indiana
733 PM EDT Fri Sep 27 2019
.SYNOPSIS...
Issued at 645 PM EDT Fri Sep 27 2019
Showers and thunderstorms are expected through the overnight
hours. A few strong to severe storms are possible through the
early overnight hours with isolated large hail and gusty winds as
the main threats. The biggest concern however will likely be
locally heavy rainfall and flooding. There also is some concern
for flash flooding especially from northwest Indiana into
southwest Lower Michigan. Additional showers and thunderstorms
are possible Saturday into early Sunday. Low temperatures tonight
will only drop into the mid and upper 60s. High temperatures on
Saturday will range from around 70 across far southwest Lower
Michigan to the lower 80s across northeast Indiana and portions of
northwest Ohio.
&&
.UPDATE...
Issued at 730 PM EDT Fri Sep 27 2019
Initial cluster of showers and storms marking leading edge of
steeper mid level lapse rates has brought pockets of heavy
rainfall of 1 to 2 inches, with localized radar estimated 3+ inch
amounts across west central Indiana (Pulaski County). Persistent
isentropic ascent over associated outflow boundary also aided in
training of these cells. With initial advective forcing beginning
to shift across northwest Ohio, attention for late evening/early
overnight will turn to northeast Illinois/northwest
Indiana/southwest Lower Michigan. Sheared, low amplitude wave
lifting across west central Illinois will continue to promote
renewed convective development from west central Illinois into
northwest Indiana. Robust shear profiles exist in association
with low level jet in pre-frontal environment, with axis of
steepest mid level lapse rates orienting itself across NW
Indiana/SW Lower Michigan late evening/early overnight. This low
level jet will also help advect a 750-1500 MLCAPE axis
northeastward into far northwest portions of the forecast area
late this evening. In mixed layer sense, still expecting enough
convective inhibition to mitigate true surface based
convective/tornado threat. Perhaps greatest concern in terms of
severe threat next several hours will be potential of isolated
large hail given combination of increasing instability,
orientation of steepest mid level lapse rates, and the possibility
of at least elevated supercell structures aiding large hail
formation. Already monitoring one storm that appears to be
producing very large hail northwest of Kankakee IL as of this
writing. Greatest severe threat should exist locally in the 01Z-
05Z period with hail as first order threat, followed by isolated
damaging wind gusts. A very brief window may still exist for
isolated tornado potential far west late this evening, but
confidence is very low.
Heavy rain will be the primary concern overnight as highly
anomalous 1.75 to 2 inch PWATS axis settles across northwest half
of the area. Large portion of shear parallel to approaching
boundary should promote cell mergers overnight with heavy rainfall
potential. Expecting areas which received heaviest rainfall
earlier today to at least get a brief break from heavier rain late
this evening, but southeast progression of frontal forcing will
shift this threat across these areas overnight. No changes
currently anticipated to flash flood watch although an eventual
slight eastward expansion may be needed.
&&
.SHORT TERM...(This Evening through Saturday)
Issued at 308 PM EDT Fri Sep 27 2019
Forecast is focused on the first 24 hours of the forecast. There are
two main hazards that could affect portions of the area during that
timeframe: Strong to Severe Storms, and Flash Flooding.
There are two rounds of convection anticipated. This first round
is the convection currently moving across the area and stretching
back into IL. The second round is expected along a slow moving
cold front late this evening/overnight.
With this first round, storms will remain initially elevated while
spreading eastwards as dewpoints in the 60s are still in east-
central IL. BUFR sounding show instability within the EML ranges
between 500 and 1000J/kg this afternoon and increases towards
1500 J/kg just prior to 00Z. Decent 0-6km and 0-3km shear of 30 to
35kt are in place across northern IN, southern Lower MI, and NW
OH and hodographs within the EML are shown to be unidirectional.
This setup would point primarily to a large hail and possibly a
damaging wind risk. So far storms have struggled to produce hail
over the size of nickels (Peoria, IL), but further destablization
is anticipated as we move further into the afternoon hours. There
is a narrow window around 00Z where low level dewpoints in the
mid-60s surge into the western zones and storms could become
surface based. Should this occur, then all hazards would be on the
take. Confidence is low, but worth a mention, as this will be a
very narrow window as soundings should low level winds veering
quickly around 00Z.
Storms with this round has shown the ability to produce locally
heavy rainfall given increasing moisture advection. These storms
should remain progressive, but recent RADAR trends show storms
could become stalled over the same location.
The second round of storms is expected this evening and overnight as
a cold front slowly drifts southwards.
The severe risk looks conditional with this round given the loss of
daytime heating, and weak height rises aloft. With that being said,
there remains decent enough instability and deep layer shear in
place for a strong to severe storm. Hail and damaging wind gusts
should be the main hazards especially given increased precip
loading of the downdrafts bringing the 40-50kt LLJ to the surface.
RUC 0-1km storm relative helicity will also be on the rise from
00Z to 06Z so there is a low, non-zero, chance for a brief tornado
generally west of HWY 31.
Looking at the flooding risk with this round: Models show a classic
Maddox frontal type heavy rain scenario this evening and overnight.
This is from the combination of surging surface dewpoints, 850mb
advection of Gulf of Mexico moisture, a Pacific moisture
teleconnection at 500mb, and a slow moving frontal boundary. Given
these factors it`s no surprise models show PWATs in the 1.75" to
2" range early this afternoon into Saturday. Late this evening
and overnight, the cold front will slowly enter the CWA. Storm
motions at that time will become parallel to the front which will
result in a prolonged period of storm training. Storm totals
have been on the up-tick throughout the day and have trended with
them. The result is up to 2 inches expected west of a White
County to Kosciusko County, IN to Cass County, MI line. Lower
amounts are expected east of this line. If the up-tick continues
in model output then amounts will need to be adjusted.
Considering the potential rainfall from both rounds of storms,
have decided to issue a Flash Flood Watch for locations west of a
White County to Kosciusko County, IN to Cass County, MI for this
afternoon through late tonight.
&&
.LONG TERM...(Saturday Night through Friday)
Issued at 308 PM EDT Fri Sep 27 2019
Front remains stalled over the area on Saturday with scattered
storms possible. Cold front start to move back north on Sunday as
high pressure builds over the southeastern US. An isolated storm
can`t be ruled out across the NW. Monday through Tuesday continue
to look very warm and dry. High temperatures could threaten a few
records. Wednesday and Thursday sees the high shift to the east
and allow another cold front to slide across the area with
associated storms. Friday into the weekend, look pleasant as
temperatures drop back towards normal for early October.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 650 PM EDT Fri Sep 27 2019
Difficult forecast for terminals regarding duration of thunder as
complicated setup continues to unfold this evening. Area of
showers and thunderstorms marking the eastward expansion of
sharp increase in elevated instability continues to track eastward
across northeast Indiana early this evening. Outflow boundary
deposited from this convection along with fairly strong low level
jet as allowed renewed storm development across northwest Indiana
and these cells have trained over the same locations just south of
the Route 30 corridor. Would expect a few more hours of
thunderstorms at KFWA to begin this period with perhaps a break
after 03Z.
Focus late evening and especially overnight should eventually
shift back across northwest Indiana into south central Lower
Michigan where sheared upper level wave lifts northeast from
Missouri and slowly southeast sagging frontal boundary result in
renewed thunderstorm development. This should provide a period of
storms at KSBN in the 04Z-08Z time window and eventually posing
best threat of more organized thunder at KFWA in the 07Z-10Z
period. Showers and storms should diminish after 10Z with a
continued chance of scattered showers into Saturday as front
stalls across the area. MVFR cigs are expected to accompany the
front tonight from northwest to southeast with a period of IFR
cigs also possible at KSBN late tonight/early Saturday.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Flash Flood Watch until 5 AM EDT /4 AM CDT/ Saturday for
INZ003>005-012>016-020.
MI...Flash Flood Watch until 5 AM EDT Saturday for MIZ077-078.
OH...NONE.
LM...Small Craft Advisory until 8 PM EDT this evening for LMZ043-046.
&&
$$
UPDATE...Marsili
SYNOPSIS...Marsili
SHORT TERM...CM
LONG TERM...CM
AVIATION...Marsili
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Area Forecast Discussion
National Weather Service Elko NV
259 PM PDT Fri Sep 27 2019
.SYNOPSIS...Strong cold front brings much cooler temperatures and
showers across the area for the next few days. Snow is likely in
the surrounding mountains, with light slushy accumulations Sunday
morning possible in some higher valleys.
&&
.SHORT TERM...Today through Sunday evening.
The promised pattern change that brings much cooler and a showery
regime has begun. Surface front has sagged and stalled out over
northern Nevada. No weather has accompanied this front aside from
a layer of altocumulus that cuts across the I80 corridor. As the
anomalous upper low pressure system continues to amplify,
increasing upwards motion along this boundary will generate
showers later this evening. The favored area will be over Elko
County with the higher resolution HRRR showing the preferred area
just north of I80. An area of convective potential does exist
southeast of Ely that includes Great Basin Natl Park, a
thunderstorm is possible for this area this evening.
Frontogenetical forcing increases as the cold deep trough pivots
into northwest Nevada by Saturday afternoon/evening time frame.
Showers will be expanding across northeast Nevada, but trailing
back into the middle part of the state. Cold air quickly spreads
across the state with 700 mb temperatures approaching -10C by
Sunday morning. Snow levels will lower Saturday evening and reach
many valleys floors overnight. The first significant snowfall will
occur in the surrounding mountains, with several inches possible
in the Rubies and a Winter Weather advisory will be issued to
account for this.
Current precipitation projections show one half inch /0.50/ to
one inch /1.00/ will fall over White Pine and eastern Elko
Counties. For other areas, lesser amounts are expected. While most
of this falls as rain in the valleys, many mountains will be snow
covered by Sunday morning. Light slushy accumulations (less than
one inch) will occur at some valleys, although Lamoille and
northern Elko County may receive 1-2 inches late Saturday night.
.LONG TERM...Sunday Night through next Friday.
Sunday and Monday. The storm system will still be present over
NV with the system rotating a band of moisture across mainly
northern NV. This moisture should still cause showers in northern
NV and the northern reaches of central NV. At the same time the
system will still be training unseasonably cold air across NV
which will see the snow levels continue to be low. This means the
showers for early next week will be mainly snow for the mountains
and high valleys to a mix for mid valleys and pure rain for the
lower valleys. The temperatures will be abnormally cold for this
time of year which will likely lead to widespread below freezing
temperatures during the overnight and morning hours.
Tuesday. The storms system will leave the region by translating to
the east with a ridge building into the area. This will lead to
the departure of the moisture with only a few remnant showers
lingering in mainly northeastern NV. The cold below freezing
temperatures should remain over NV during the overnight and
morning hours as well.
Wednesday through Friday. The pattern should become a bit more
progressive during the mid and latter portions of next week with
a ridge followed by a weak trough. This time should be a mainly
dry period with the exception of light rain possible on Thursday.
Temperatures should warm during this period as well but be still
be below normal overall.
&&
.AVIATION...VFR conditions will continue across northern and
central Nevada today though it is breezy. A Storm system is
beginning to move in to area with rain showers developing in Elko
County today and then expand in coverage tonight into Saturday.
The weekend will see the full system which will produce widespread
rain and snow showers. Snow levels will plummet with this system
with the snow expected to reach to the valley floors. This will
lead mountain obscurations throughout all of NV. In addition lower
clouds decks will be present at KELY which should be MVFR with
the system passage.
&&
.FIRE WEATHER...
With colder and wetter weather arriving, there are no fire weather
concerns for the next several days.
&&
.LKN WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 PM Saturday to noon PDT Sunday
for Ruby Mountains/East Humboldt Range.
&&
$$
88/99/99/88
Area Forecast Discussion
National Weather Service Marquette MI
728 PM EDT Fri Sep 27 2019
.SHORT TERM...(This evening through Saturday)
Issued at 218 PM EDT FRI SEP 27 2019
RAP analysis indicates that the sfc low has quickly exited to the
northeast and will reach James Bay before 20Z. Sfc obs show that the
attendant cold front is just now beginning to push into IWD from the
west as of 18Z, but the drier airmass will trail about 6 hours
behind the front. Only a few isolated light rain showers remain over
the west half, with some heavier showers stretching SW to NE through
Menominee/Delta/Schoolcraft/E Alger counties along a band of 800-750
mb Fgen well ahead of the sfc front. May be a rumble of thunder or
two in this area through the early evening. Showers will gradually
diminish and exit east through this evening, drying out completely
after midnight.
Wind gusts have struggled at times to mix all the way to the surface
today but there have been several spots with gusts in the 25-30 mph
range. As the low continues to exit this afternoon and evening,
winds will continue to diminish as they shift to NWerly behind the
front. However, over the eastern UP and especially along the Lake
Superior shoreline there will be another period with 10-20+ mph
gusts overnight as high pressure building in from the west keeps the
pressure gradient moderately strong over that region.
Skies are expected to gradually clear from west to east through
tonight, and some locations may have a decent chance to go Aurora
hunting as the SWPC has a G2 geomagnetic storm watch in place. Pack
a jacket though, as temperatures will be chilly! Should be just
enough turbulence over the west as well to prevent frost formation
but forecast lows are in the mid 30s over the interior with 40s
expected lakeside. Tomorrow looks nice, with calmer winds and mostly
clear skies, but highs will struggle to reach 60 for most.
.LONG TERM...(Saturday night through Friday)
Issued at 442 PM EDT FRI SEP 27 2019
A trough amplifying over the western CONUS tonight into Saturday
will result in a downstream ridge over the eastern CONUS later this
weekend into early next week. As a result, there may be one or
perhaps two, warm days (solidly above normal temps) early next week
as an ejecting shortwave from the western trough sends an associated
sfc low on a northeastward track just nw of Upper MI, placing the
fcst area briefly in the warm sector. Warm advection ahead of the
sfc low will result in the best chance of widespread rain late Sun
into Mon. There will likely be lingering chances for showers into
Tue as the cold frontal boundary with the early week`s system works
its way through the area. Thereafter, models are trending toward
some degree of troughing in se Canada which will allow cooler
conditions (probably a few days of blo normal temps) to prevail
until next weekend as sfc high pressure builds into the region. May
even be some isolated lake effect rain showers in a ne flow
lingering into midweek for west and north central sections.
Sat night/Sun, high pressure should remain firmly in control,
keeping conditions dry through the much of the period. Under clear
skies at least into the evening hours, could be a little patchy
frost forming over interior locations west and central Sat night as
readings dip toward the mid 30s. 40s readings are expected along the
Great Lakes shores. Increasing WAA ahead of a shortwave and
associated sfc low lifting northward through the Plains, may produce
a little light rain into the WI border counties late Sunday. Highs
Sun will be mostly in the upper 50s and lower 60s under increasing
cloud cover.
During Sun night, approach of sfc warm front, nose of 40-50kt low-
level jet aimed toward Upper MI and advection of elevated
instability of 500-1000 j/kg toward the area should yield more
widespread rain and sct t-storms. With precipitable water surging up
to around 1.5 inches, 200-250pct of normal, heavy rainfall will be
possible.
Rain will diminish to scattered showers on Mon as the sfc warm front
lifts n of Upper MI. If the front does lift n, it will become a
warm/humid day with high temps generally in the lower to mid 70s and
dewpoints into the 60s.
Tue, as the shortwave lifts across northern Ontario this will push
the system`s cold front southeast across the area. Placement of the
front will be important as it will become a focus for episodes of
moderate to heavy rainfall. Models continue to fcst a gradient
across the fcst area with lowest chc of showers nw and highest
potential southeast. High temps will fall back to the 60s Tue under
clouds and pcpn and developing northerly onshore flow developing
behind the front.
Wed into Fri, the cold front is expected to push farther southeast
of the area on Wed with sfc high pressure building in from
Ontario/Manitoba. This should result in a general drying trend for
the area mid to late week, however with one caveat. Models do
indicate a pretty cool air mass advecting in behind the front with
850 mb temps dropping as low as -2C. This combination of colder air
and any sw flow shortwave advecting across the area could spawn
periods of scattered lake effect rain showers, especially into the
west and north central sections of the cwa Wed-Thu where showers
will be more favored in upslope/onshore ne flow. High temps will
fall back into the 50s on Wed, and some higher terrain locations
over the w and n central may see high temps drop into the upper 40s
on Thu.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 728 PM EDT FRI SEP 27 2019
Ceilings continue to improve early this evening with all three sites
reporting MVFR/VFR at this time. Only concern in the first few hours
of the forecast is at KCMX, where northerly winds may advect in
enough moisture to lower ceilings IFR for a few hours before drier
air works in. As the cold front continues to push through the region
and high pressure builds in, light winds and VFR conditions will
prevail through the forecast.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 242 PM EDT FRI SEP 27 2019
A cold front located from just east of Isle Royale to near Houghton
to near Land-o-Lakes WI this afternoon will continue eastward this
evening and tonight. Behind the front winds shift to NW and relax
back to around 20 kts over the east and lower over the west
overnight. They subside further on Saturday to below 15 kts as high
pressure moves overhead. The next strong system approaches Lake
Superior Monday with some strong E winds to 25 kts possible as early
as Sunday evening over the western lake. Winds of 20-30 kts out of
the SE are possible over the eastern lake Monday morning. Otherwise,
winds should remain at or below 20 knots.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KCW
LONG TERM...Voss
AVIATION...RJT
MARINE...KCW
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
850 PM EDT Fri Sep 27 2019
.SYNOPSIS...
A warm front will continue to lift north through central NC tonight.
A strong high pressure ridge aloft will build over the Gulf and
Southeast states through the weekend, resulting in continued above
normal temperatures. A backdoor front will then drop southward
through the region early Monday, with high pressure nosing in from
the northeast Monday into Tuesday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 835 PM Friday...
Scattered storms continue to wax and wane along a warm front and
merged seabreeze/outflows moving north through the CWA....stretching
from approx CLT-HRJ-ISO-MHX. Storms have been sub-severe criteria
until recently with a couple storms in Harnett and Hoke Counties
show signs of depth and wet-downburst potential. Expect the
northward migration of showers and storms to continue to the north
through midnight but with an overall decreasing trend in coverage
after midnight, with just a shower or two in the northern Piedmont
in the morning...per latest HRRR runs. Some patchy fog is possible
but coverage seems too low to add to the forecast given scattered
mid-clouds and widespread anvil blow off for much of the area. Lows
67-71.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
As of 415 PM Friday...
More warm weather is on tap for Saturday as the stalled front
from Friday will be well north of the region. This will be
thanks to a mid-level ridge slowly amplifying over the northern
Gulf of Mexico. 1000/850 MB thicknesses are forecast to be
around 1420 M with 850 MB temperatures around 18 degrees C.
These type of values will easily support high temperatures near
90 degrees. Most of the area will be dry Saturday with the
exception being a slight chance of a storm moving off the
mountains towards the Piedmont in the late afternoon.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 235 PM Friday...
Mid and upper level ridge centered over the northern GOMEX and
Southeast Coast today will expand once again across the southeastern
quad of the US next week, resulting in another spell of temps 10-15
degrees or more above normal and mostly dry conditions. The lone
period in the extended with higher uncertainty will be late Sun
through late Mon, when a backdoor front is progged to slip down the
mid-Atlantic coast and into central NC. Medium range guidance
suggests some showers or an isolated storm mainly in the northeast
CWA late Sunday amidst weak destablization ahead of the sfc-925mb
front frontal zone, though the low level convergence and overall
forcing looks weak. Will keep a 20-25 POP in for the afternoon and
a 15-20 POP in the southern CWA overnight as the front slips south.
Northeasterly flow behind the front should support some stratus
across the northeast CWA early Monday, transitioning to or
developing in the western Piedmont later Monday as the 925mb flow
becomes more east-southeasterly. A few showers are possible but
again mostly areas will remain dry with temps low to mid 80s.
The heat returns for the latter half of the week, with 850mb temps
again approaching or exceeding 20C by Thursday ion pre-frontal
westerly flow and guidance in pretty good agreement on upper 80s
Wednesday to solid lower 90s Thursday. This would again break high
temp records. A long awaited strong front is then forecast to move
into the area Friday and bring temps plummeting back to normal
&&
.AVIATION /00Z SATURDAY THROUGH THURSDAY/...
As of 740 PM Friday...
24 hour TAF period: A front remains stalled across central NC,
roughly south of KRDU and KRWI, north of KFAY. Showers and storms
across the south (KFAY) will likely continue for the next few hours
or so, with reduced visbys and gusty winds where they occur.
Otherwise, VFR conditions are expected at KINT, KGSO, and KRDU for
much of the evening. A period of sub-vfr cigs and visbys is possible
at all sites overnight, earliest at KRWI and possibly not at all at
KFAY. Confidence is somewhat low regarding the occurrence, location
and duration of the reduced cigs and visbys. As the stalled surface
boundary lifts northward through the remainder of the area through
Saturday morning, it should help improve aviation conditions back to
VFR at KRWI and KRDU toward daybreak and elsewhere thereafter. -KC
Looking ahead: A weak cold front will cross the region Monday
morning with stratus likely developing across the eastern TAF sites
and then spreading west. MVFR/ IFR conditions could then continue
into Monday afternoon. -Haines
&&
.CLIMATE...
Record High Temperatures (Year)
GSO RDU FAY
9/27 90 (2017) 94 (1998) 94 (2017)
9/28 92 (1939) 95 (1998) 95 (2017)
The Piedmont Triad International Airport (KGSO) has only
received 0.02" of rainfall for the month of September as of the
27th. If KGSO does not receive any more rainfall this month, this
will be the second driest September on record (1903- Present).
Year September Rainfall (inches)
1985 T
2019 0.02"*
1939 0.13"
1961 0.20"
2005 0.23"
*As of September 27th.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Haines
NEAR TERM...Smith
SHORT TERM...Haines
LONG TERM...Smith
AVIATION...KC/Haines
CLIMATE...CC/ Haines
Area Forecast Discussion
National Weather Service Topeka KS
553 PM CDT Fri Sep 27 2019
.MESOSCALE DISCUSSION...
Issued at 553 PM CDT Fri Sep 27 2019
The RAP and NAM solutions show increasing low level convergence
along the frontal boundary across south central KS where latest
satellite imagery indicates some convective updrafts trying to
develop. All of the CAMs have been consistent in storms developing
along the boundary around 00Z. Initially storms will be capable of
damaging hail and winds as deep layer shear around 45KT and 3000
to 4000 J/kg of CAPE promote severe storms. The NAM and GFS
forecast soundings show the 0-3km hodograph becoming more curved
and expansive as the low level jet strengthens. This causes 0-1km
SRH in increase as well to around 300 m2/s2. Think by this time
storms will be pretty much a broken line along the boundary, but
there could be some potential for a tornado after sunset.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 320 PM CDT Fri Sep 27 2019
As of 19Z this afternoon, a surface cold front is progressing
southward across northeast Kansas, with the boundary located just
northwest of Manhattan. The boundary will continue southward across
the forecast area into this evening before stalling in east-central
Kansas overnight. The airmass ahead of the front has become very hot
and humid, especially for this time of the year, with temperatures
in the low 90s and dewpoints in the upper 60s/low 70s. Instability
will continue to build along and ahead of the front with models
showing 3000 to 4000 J/Kg of CAPE into the evening hours, primarily
near and south of the Kansas Turnpike. Looking at shear parameters
near the boundary, directional shear is lacking due to primarily
southwesterly flow through the column. Speed shear is more
impressive as a result of stronger winds aloft. Thus, effective bulk
shear values are expected to range from 30 to 40 kts just ahead of
the boundary with higher values behind it.
Thunderstorms are expected to develop along the boundary between 23Z
and 01Z , with the most likely area of storm initiation along a line
extending from near Emporia to near Topeka. Strong to severe storms
will be possible given the amount of instability and shear in place.
Large hail is looking like one of the main hazards of concern.
Damaging wind will also be possible with DCAPE values exceeding 1000
J/Kg. Additionally, localized flash flooding will also be possible,
especially where storms train over the same locations, with models
showing precipitable water values increasing to near climatology
max for this time of the year.
Elevated storms will continue to be possible through the overnight
period north of the frontal boundary as a result of isentropic
ascent near the 850 mb front which will be located northwest of the
surface boundary. Thus, rain will become possible over locations
north of I-70 as we transition into the nighttime period.
Going into Saturday, the surface warm front continues to be stalled
along the I-35 corridor, with a baroclinic zone set up to the
southeast. The overall placement of this front still has a great
deal of uncertainty, with some disagreement between the
deterministic models and even greater spread between the SREF
members. Southerly flow south of the front will continue to enhance
the gradients of temperature, moisture, and instability through the
day.
Saturday`s severe chances continue to be of concern, with continued
southwesterly flow in the mid/upper levels expected to steer a
shortwave trough through the CWA. This will provide chances at
ignition all along the front in the afternoon. Forecast hodographs
continue to show good low-level backing of winds from 0-1 km AGL.
Southern sections of the CWA will have surface-based CAPE values
climbing to over 2000 J/kg, providing sufficient energy for strong
storms once initiation occurs. Storms should spread southwest to
northeast across the region. Initial convective mode could take on
super cellular characteristics initially, but will most likely
become less organized as they grow upscale. Winds and hail are the
primary concern, but cannot rule out an isolated tornado or two.
Storms should be rather progressive in their movement through the
evening. PWAT`s continue to be well above the seasonal average,
introducing flooding concerns. Storm total rainfall look to range
from 1 to 3 inches, with the higher amounts being focused wherever
training occurs. The best chances for flooding currently look to be
south and east of I-35.
.LONG TERM...(Saturday night through Friday)
Issued at 320 PM CDT Fri Sep 27 2019
Transitioning into the extended period, an active weather pattern
looks to continue into next week. Any lingering showers and storms
look to end early Sunday as midlevel heights rapidly rise and the
surface baroclinic zone progresses well north. Dry conditions are
expected to continue through Monday as any notable shortwave troughs
remain well north of the area with the main midlevel trough
remaining across the western CONUS. The next good chance for showers
and storms looks to arrive through the day Tuesday as a stronger
shortwave trough ejects across the Northern Plains shunting an
attendant surface trough into the area. Sufficient shear and
instability is likely to be in place for the potential for severe
thunderstorms, especially Tuesday afternoon. In addition, the front
looks to be slow moving with the detachment of the midlevel
shortwave across the Northern Plains. This will unfortunately set
the stage for multiple rounds of heavy rainfall Tuesday into
Thursday. Temperatures look to remain in the 80s prior to the
arrival of the aforementioned surface front. Temperatures are likely
to be notably cooler by Wednesday with highs in the 60s and 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday)
Issued at 553 PM CDT Fri Sep 27 2019
Confidence is increasing in TS impacting the terminals this
evening. Will use the CAMs to base timing of storms. Otherwise low
clouds are expected to build in overnight and not leave the
region. In fact models maintain an easterly wind over the area for
much of the day with the frontal boundary remaining to the south
of the terminals. This looks to be a favorable setup for MVFR or
IFR CIGS to persist through much of the day Saturday.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...Wolters
SHORT TERM...Teefey/Petersen
LONG TERM...Baerg
AVIATION...Wolters