Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/22/19
Area Forecast Discussion
National Weather Service Billings MT
723 PM MDT Tue May 21 2019
.UPDATE...
Rain continues this evening across much of the cwa under
persistent isentropic ascent and easterly diffluent flow aloft.
Have maxed out pops for our west and south. Only exception is in
our northeast (i.e. Miles City to Baker) where drier northeast
winds will keep precip lighter and more spotty. Latest RAP shows
wet bulb zero heights falling to 4500-5000 ft msl tonight, so a
mix with or change to wet snow along the foothills (Red Lodge,
Nye, Story, etc) is a good bet. Latest surface analysis shows
temps in the low-mid 30s at these locations already. Forecast has
this covered well. JKL
&&
.SHORT TERM...valid for Wed and Thu...
OVERVIEW: Doubled barreled upper low dominates over the Rockies
and upper midwest. One portion of this upper trough will
transition to the Great lakes area by Wednesday evening. As the
other cut off upper low drops south toward the desert SW. Cool
easterly low level flow will turn more northerly tonight into
Wednesday. This will favor upslope flow into the Beartooth
Foothills and NE facing Big Horns. By Thursday, the upper low to
the south tracks over our region. The newer solutions of the GFS
and EC cut off moisture for a time on Thursday, which reduces the
chance of precipitation. So for this package, we have trended
PoP`s down for Thursday and raised afternoon highs a bit.
Forecast issues: With the low level flow turning more
north/northeasterly tonight into Wednesday, there may be a little
more cooling in foothill locations and more efficient
precipitation production due to upslope. This includes Nye to Red
Lodge, and the Dayton to Story area in the Sheridan Foothills.
Most of the snowfall will likely melt on roadways, but areas could
become slick late tonight into the morning rush hour. Plus, any
snow accumulation could collect on new spring foliage and push
down nearby power lines. Confidence in this scenario is low, but
given the unusual cool temperatures and forcing aloft, seems
prudent to issue winter weather advisories for these areas tonight
through 10 am Wednesday morning.
IMPACTS: Areal flooding remains a concern this week. However,
model QPF has trended downward overall. Major rivers, such as the
Yellowstone, have plenty of room to handle additional rainfall.
Main concern are low-lying areas, such as ditches, roads and
smaller creeks across the CWA. The Little Goose Creek and others
in the Sheridan foothills could very well experience minor
flooding. BT
.LONG TERM...valid for Fri...Sat...Sun...Mon...Tue...
The long term continues to look unsettled with multiple
disturbances bringing additional chances for precipitation. An
upper low lifting north and east through Wyoming and eastern
Montana on Friday will bring widespread precipitation, with the
greatest totals over far eastern Montana. Overall drier
conditions then look to move into the area Friday night through
Sunday with some afternoon and evening showers and thunderstorms
possible, especially over western areas. Yet another upper low is
progged to track out of the Great Basin and off to the north and
east early next week, increasing precipitation chances for Monday
and Tuesday. Uncertainty exists in regards to the track of the
low. These look to be warmer systems, with snow confined to the
mountains. High temperatures will climb into the 60s for the
weekend and continue into next week. Low temperatures in the 40s
look possible most nights/mornings. STP
&&
.AVIATION...
Widespread precipitation will bring MVFR/IFR and locally lower
flight conditions through tonight and much of Wednesday. Only
exception to this is from KMLS to KBHK where drier air will limit
flight reductions to MVFR at times. Mountains will remain obscured
in snowfall through the period. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
Wed Thu Fri Sat Sun Mon Tue
-----------------------------------------------------------
BIL 039/051 040/053 040/060 042/065 045/061 046/062 047/065
+8/R 55/W 63/W 12/T 36/T 45/T 43/W
LVM 036/048 036/051 035/058 038/062 041/058 041/060 041/063
+8/O 56/W 43/T 25/T 46/T 46/T 44/T
HDN 039/050 037/054 039/060 040/066 044/063 045/063 045/067
+7/R 55/W 64/W 12/T 26/T 45/T 54/W
MLS 040/053 039/056 040/058 040/066 044/062 044/062 045/065
86/R 34/W 76/W 11/U 23/W 45/T 33/W
4BQ 038/047 036/053 039/057 039/065 044/064 045/061 045/062
+9/O 45/W 74/W 01/U 25/T 46/T 43/W
BHK 038/050 036/055 038/055 038/063 041/060 042/058 041/062
78/R 43/W 87/W 11/U 13/W 35/T 33/W
SHR 034/045 033/049 034/057 036/063 040/062 042/062 042/062
+9/O 66/W 63/T 12/T 26/T 55/T 54/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Flood Watch in effect from midnight MDT tonight through
Saturday morning FOR ZONES 28>33-35>39-42-56>58-63-67-68.
Winter Weather Advisory in effect until 10 AM MDT Wednesday
FOR ZONES 56-66.
Winter Storm Warning in effect until 10 AM MDT Thursday FOR
ZONES 67-68.
WY...Flood Watch in effect from midnight MDT tonight through
Saturday morning FOR ZONES 98-99.
Winter Weather Advisory in effect until 10 AM MDT Wednesday
FOR ZONE 99.
Winter Storm Warning in effect until 10 AM MDT Thursday FOR
ZONE 98.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Des Moines IA
706 PM CDT Tue May 21 2019
.DISCUSSION.../Tonight through Tuesday/
Issued at 352 PM CDT Tue May 21 2019
Overall, looking at an active period of weather over the course of
the next week or so with multiple chances for severe weather and
rainfall continuing to prime additional river flooding and
increasing the flash flooding potential.
Upper level low pressure easily seen on the early afternoon GOES-
East Clean IR Water Vapor imagery over southwest Kansas with a broad
shield of clouds and precipitation to the north, northeast, and
east. Locally over Iowa, there is a large area of rain over central
spreading into eastern Iowa. This coincides with theta-e advection
that is moving in a similar direction along with strong Q-vector
convergence. There is a narrow window immediately following the
dissipating/ending rain of strong wind gusts with recent gusts at
the Carroll AWOS to 53 mph, Atlantic CWOP to 50 mph, Denison AWOS to
50 mph, Estherville ASOS to 51 mph, and Marshalltown ASOS to 50 mph.
This strong wind gusts look to continue with the 00z HREF and less
so the 12z HREF 4 hour max wind gusts, 00z NCAR Ensemble max wind
speeds, and runs of the HRRR continuing to signal strong winds
between 50 to 60 knots over north central Iowa. As previous
discussion noted, this is likely part synoptic/part convective
induced. With this potential seemingly being realized over the
southwest forecast area in agreement with model guidance, will allow
the Wind Advisory to cover this potential up north and if need be
upgrade to High Wind Warning. These wind gusts are on top of the
sustained, strong easterly winds that have been prevailing today.
Temperatures so far on this damp and windy day are near their
minimum maximums in some places, including DSM where the record is
53. So far today through 18z, the high has been 50. Still 8 or so
hours for temperatures to bump up before anything is considered
official.
Another area of showers is expected to move up out of western
Missouri into central Iowa, but instability is limited through early
this evening with MUCAPE less than 500 J/kg so a few thunderstorms
are possible over southern Iowa as this activity moves in. These
elevated storms may pose a risk of near severe hail, though threat
currently seems quite low. Currently, the nearest lightning via GOES-
East GLM data is over central Missouri/roughly I-70 south at
mid-afternoon. Several additional rounds of showers and storms
are expected tonight, but areal coverage will be much less so than
current ongoing precipitation. As the upper low mentioned above
lifts north-northeastward into central Nebraska, shortwaves will
rotate around and into southwest Iowa. The first wave will be late
this afternoon/early this evening roughly arriving 23-00z over
southwest Iowa and moving generally northward. Currently expect
these to be more scattered showers with very limited instability.
The next wave will arrive several hours later around 4 to 5z over
southwest Iowa. This will have perhaps the best instability of the
`day` with the HRRR indicating between 500 to 1000 J/kg with the
RAP closer to 250 J/kg. Deep layer bulk shear is strong between 40
to 50 knots with 0-3 km helicity above 200 m2/s2 with 0-1km
helicity similar. Interestingly, the last three runs of the HRRR
has an updraft helicity track indicative of a strong, rotating
storm over our far western area say from roughly Union up through
Carroll County. The HRRR has been consistent with this with slight
shifts east and west with runs. If surface based storms are able
to form, shear environment is favorable for rotating storms so
tornado threat would be non-zero along with hail and wind gust
potential. This threat should wane after midnight, but showers
will linger over the northern part of the forecast area into early
Wednesday morning.
As the upper low continues slowly northeastward into the Red River
Valley of the North, winds will remain breezy over the state from
the southwest, though certainly not as strong as today. A surface
boundary will lay out over southeastern Iowa and will serve as a
focus for storms Wednesday evening as weak warm air advection passes
over the area. While instability will be weak, there will be strong
deep layer shear again that could support some large hail or perhaps
gusty winds. The western US trough will eject out another shortwave
trough in the southwest flow later Thursday. The boundary that was
the focus for storms Wednesday evening will lift northward as a warm
front and bring back a moisture rich environment with precipitable
water values increasing to 1.5 to 2 inches by Thursday night. CAPE
values will increase as well into the overnight towards 1000 J/kg
with deep layer shear in excess of 40 to 50 knots. Expect storms to
form as the low level jet strengthens into southern Iowa with
primarily elevated storms posing a risk of hail. Flash flooding
concerns will be monitored given the precipitable water values and
storm totals between 1 to locally 3 inches.
The rest of Friday through Memorial Day will continue to have
chances for showers and storms with temperatures generally above
normal for late May. With southwest flow remaining aloft allowing
for shortwave troughs to move across the region and a surface
boundary somewhere in the vicinity of Iowa, hard to find a period at
this time frame that would be dry. That is not to say the weekend
will be a washout, just hard to nail down a time period at this time
horizon. Given the boundary location, strong to perhaps severe
storms could be possible as well. In addition, depending on where
rains set up, the flash flooding and river flooding concerns may
grow as well through the weekend
&&
.AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/
Issued at 706 PM CDT Tue May 21 2019
Widespread showers and IFR ceilings will gradually clear out from
south to north late this evening and tonight, with perhaps a
period of additional showers and thunderstorms that may affect
FOD/DSM briefly overnight. Overall trend in ceiling heights will
be up, with VFR conditions expected before sunrise Wednesday.
Brisk and gusty east southeast winds this evening will turn
through southeast to southwest by Wednesday afternoon, resulting
in changing crosswinds on runways. LLWS of 40-50 KT is also
anticipated at times overnight.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 10 PM CDT this evening for IAZ004>007-
015>017-023>028-033>039-049-050.
&&
$$
DISCUSSION...Ansorge
AVIATION...Lee
Area Forecast Discussion
National Weather Service Quad Cities IA IL
936 PM CDT Tue May 21 2019
.UPDATE...
Issued at 931 PM CDT Tue May 21 2019
I have cleared the western 1/2 of the Flash Flood Watch, as the
rains have ended. Over all, the current flash flood threat appears
low, with fast moving heavy showers not lasting long enough to
deposit large amounts of rain. The over all band of rain and heavy
showers is putting down generally 0.25 to 0.5 over the eastern
half of the area, not that it`s more progressive. Farther west, it
did produce 0.5 to 1 inch amounts. I will continue to clear
counties as the rain band pushes east tonight.
There is a period of strong east winds as the rain ends, which we
are handling with an SPS. This is short lived, with sites
returning to below 30 mph over locations farther than 30 miles
west of the back edge of rain. That wind pulse should continue to
move with the back edge of the rain east tonight.
&&
.SYNOPSIS...
Issued at 337 PM CDT Tue May 21 2019
Vigorous negative tilt shortwave seen in GOES-16 water vapor and
RAP Mesocale Analysis lifting northward across western KS.
Attendant deepening surface low (992mb) was north of Dodge City
KS, with triple point over E OK and warm front extending eastward
across far northern AR. This was providing focus for linear MCS
across western AR/MO. Closer to home, Great Lakes ridge has been
dominant on our weather for now. Strong easterly flow and cloud
cover is resulting in a chilly late May day, with temperatures
holding fairly steady around 50 or in the lower 50s. Normal highs
are in the lower to mid 70s, so we`re running about 20-25+ degs
below. Winds have been quite strong and sustained near 30 mph and
gusting over 40 mph in a few locations, in strengthening pressure
gradient between the Plains low and Great Lakes high. The lifting
shortwave and surging elevated moisture transport will continue
to fuel expansive rain shield across the area through this evening.
&&
.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 337 PM CDT Tue May 21 2019
Rain will continue to overspread the area through this evening,
with increasingly diffluent flow east of vigorous Plains
shortwave, and strong moisture transport with PWATS surging over
1.5 to 1.6 inches taking aim on the region. Best potential
for embedded convection perhaps taking on an elevated linear
presentation exists generally near/south of I-80. Convection will
be rooted above 850 mb boundary and shallow with vertical extent
through 700 mb or so being deeply saturated above per forecast
soundings. This will be atop a brisk stable easterly low level in
deep saturation. This will make severe weather unlikely, in the
absence of any strong elevated meso. Have kept flash flood watch
going along/south of I-80 due to sensitivity to additional heavy
rain, and with the anomalous moisture feed aimed into the region.
Hopefully though the lack of deep convection and fast motions
will limit rainfall amounts and preclude substantial heavy rains.
Also, may get help from stratification especially going north
through the CWA. In general the heaviest rain swaths are anticipated
to be around 0.5 to 1 inch. Temperatures will be steady tonight,
with some rise late as the triple point lifts into the region.
Wednesday and Wednesday night... Shortwave and attendant surface
low will continue to pull away lifting across the eastern Dakotas
and MN. Trailing cold front sagging through the region may serve
as a focus for convection toward evening, with a weakening mid
level cap aided by cooling aloft with ascent from weak low
amplitude wave in SW flow aloft. Impressive 0-6km bulk shear
50-60+ kts, and MUCAPE 1000-2000 J/kg supportive of supercell
storm structures. Ideal WBZ heights around 8500-9000 ft agl, dry
air aloft and steep lapse rates in -10c to -30c layer very
favorable for large hail potentially significant. Classic inverted
V signature sub-cloud would bring an attendant damaging wind
potential mostly prior to nightfall and stabilizing BL. Tornado
potential is low with generally deep SSW flow, but would exist
with any backing of the low level winds given 0-1km shear progged
around 20+ kts. Timing of the severe threat is 5 PM to 10 PM,
mainly south/east of a Freeport, IL to Washington, IA line.
Gusty SW winds 20-30+ mph on deep mixing to around 850 mb combined
with partly to mostly sunny skies, should propel highs well into
the 70s to lower 80s Wed PM. A marked change, and considerable
improvement over highs from today.
.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 337 PM CDT Tue May 21 2019
Active weather continues throughout with chances for rain and
thunderstorms nearly every period, after a brief lull during the day
Thursday.
Thursday: A passing upper level ridge and weak ridging at the
surface should lead to a quite weather day with sunshine at least to
start the day and temperatures warming into the 70s and comfortable
dewpoints in the 50s.
Thursday night into Friday, an upper level wave passing to the
northwest will lift a warm front across the area late Thursday
night, returning the high moisture airmass to the region. This will
also bring back the potential for heavy rainfall and severe storms,
initially with the warm front, then in the diurnal instability and
convergence with a subtle cold front through Friday night. SPC
currently has a marginal risk over the southwest for Thursday, then
a 15 percent outlooked for Friday. This will also bring summer-like
humidity, with highs in the lower 80s and dewpoints well into the
60s.
With the boundary lingering in the region through the weekend into
at least early next week under an active southwest to zonal flow
aloft, low confidence chances for rain and thunderstorms cannot be
ruled out in any period. This does not necessarily depict a rain out
for the weekend, as there will likely be some dry stretches between
systems. Temperatures will be dependent on the timing of these
systems and for now the forecast has highs averaged in the 70s and
lows in the 50s and 60s throughout.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
ISSUED AT 626 PM CDT Tue May 21 2019
A strong storm system will move northeast into Minnesota tonight,
helping turn the strong east winds to the south overnight.
Initially, a band of moderate to brief heavy rainfall will sweep
northeast through all sites between 00z and 06z this evening.
While thunder is a low threat, I have only mentioned it at BRL,
where a VCTS is mentioned. Beyond a isolated lightning strike,
there should be not difference in conditions with the passing band
of rain from those that happen to see a strike. Windy, 20 to 35
kts east winds will become southerly towards morning and will
slowly decrease through the night, to the 15 to 25 kt window. CIGS
will be variably MVFR this evening, as passing showers roll
through, and consistently MVFR overnight behind the rain, until
the winds become southerly and help bring in VFR conditions for
most of Wednesday. There is a low chance for storms Wednesday
afternoon, which may be considered for the 06Z TAF issuance.
&&
.HYDROLOGY...
Issued at 908 PM CDT Tue May 21 2019
No significant changes have been made on evening updates to area
rivers, as the event is taking place as expected with only a few
potential differences from earlier forecast. These differences can
wait until the morning precipitation analysis to be accounted for
with greater certainty.
Rain amounts have been a bit lower than forecast thus far, and are
expected to coming in with totals mainly between 0.25 and 0.75".
For locations near and east of the Mississippi River, amounts are
coming in lower than predicted, and have the biggest potential to
lower forecasts a bit. This is mainly noted at three sites
tonight, first, at the La Moine River at Colmar. It was modeled to
reach moderate based on 1.25" rains, but that didn`t happen, and I
have lowered the forecast to keep it in Minor tonight, which will
be updated again using the gage correction QPE tonight around 11
PM.
The others are the Des Moines River at St. Francisville and the
Wapsipinicon at DeWitt 4S. They are kept in watch, since amounts
are lower than guidance initially used for and they just barely
reach flood stage in over 24 hours. Thus, a more accurate warning
or cancellation can be issued tomorrow morning.
Previous discussion...
Issued at 1247 PM CDT Tue May 21 2019
Overnight rainfall occurred mainly south of the I-80 corridor, with
the most significant amounts south of the highway 34 corridor.
Radar and surface observations indicated amounts from roughly 1 to
1.25 inches fell south of a line from Princeton to Galesburg in
IL, and Burlington to Bloomfield in Iowa. The resulting runoff has
resulted in rising river levels prompting new flood warnings for
the La Moine River at Colmar, the Fox River at Wayland and the
Skunk River at Augusta. The Des Moines River at St Francisville
saw a quick crest below flood stage, but is now forecast to return
to flood stage Thursday, based on forecast rainfall over the next
24 hours. With limited confidence in the rainfall amounts and
coverage, a watch has been issued for this location.
The latest river forecasts from this morning now incorporate
forecast rainfall from the system expected to impact the area
tonight. The has resulted in faster rises, and even a few additional
crests on many tributary rivers. The Wapsipinicon River at DeWitt is
now depicted to reach well into Minor flooding Saturday. With
limited confidence in the forecast rainfall, we have issued a FLood
Watch for this forecast point.
On the Mississippi River, Dubuque LD11 is now forecast to reach
Moderate flooding early next week and a flood category upgrade was
issued. Further downstream, the new forecasts have upgrades to Major
flooding at New Boston and Keokuk. Elsewhere, there was an
overall trend of additional rises or faster rises than previous
forecasts.
With the likelihood of rainfall impacting the area, to some extent,
each day in the forecast from Thursday onward, there remains low
confidence in the stage forecasts on both tributary rivers and the
Mississippi River beyond the first couple days.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Flash Flood Watch until midnight CDT tonight for Scott.
IL...Flash Flood Watch until midnight CDT tonight for Bureau-
Henderson-Henry IL-McDonough-Mercer-Putnam-Rock Island-
Warren.
MO...NONE.
&&
$$
UPDATE...Ervin
SYNOPSIS...McClure
SHORT TERM...McClure
LONG TERM...Sheets
AVIATION...Ervin
HYDROLOGY...Ervin
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
701 PM CDT Tue May 21 2019
.SHORT TERM... (Through Late Wednesday Night)
Issued at 437 PM CDT Tue May 21 2019
Line of thunderstorms is expected to move northeast across the CWA
late this afternoon and early this evening. Atmosphere has rapidly
destabilized ahead of it as 60s and lower 70 dewpoints have surged
north into the southern CWA allowing for MLCAPES to jump into the
1000-1500+ J/kg range. This is further evidenced by the appearance
of a well developed cumulus field that is moving northward into
the CWA. Latest RAP low level convergence fields supports CAMS
simulated reflectivity which depicts the current line progressing
eastward across the CWA through the evening. Deep layer and low
layer shear supports the line producing damaging winds with
embedded tornadoes and perhaps some hail given the steep lapse
rates. In addition any discrete storms that do develop ahead of
the line will also be capable of producing all hazards.
Will continue the flash flood watch until midnight. While the line
will be progressive, it will have very heavy rainfall rates.
Therefore cannot rule out a flash flood threat given the already
wet ground over the area. This line will move east of the CWA
after midnight with dry conditions expect by 12Z.
Wednesday looks like about one of the only dry days as the there
will be no upper systems moving across the area. By Wednesday
night however, both the NAM/GFS are showing another weak shortwave
moving over the area at the some time that a front will be aligned
over Missouri and Illinois. Will go with a chance of showers and
thunderstorms as there may be some chance for a few strong storms.
Britt
.LONG TERM... (Thursday through Next Tuesday)
Issued at 437 PM CDT Tue May 21 2019
The extended part of the forecast will be highlighted by warm
temperatures and a chance of thunderstorms through the Memorial
Day weekend. The GEFS and deterministic models are in reasonable
agreement into early next week that east-west front set up
underneath quasi-zonal upper flow. This will be between a large
upper high over the southeastern CONUS and trough over the
southwest. Coverage of thunderstorms over our area will be
determined by the ultimate location of the front and how much
upper ridging will be over the CWA. For now will keep with above
normal temperatures given forecast 850mb temperatures between
15-20C and a persistent chance of thunderstorms.
Britt
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 641 PM CDT Tue May 21 2019
A line of thunderstorms will continue to affect the St. Louis area
terminals through 01Z before moving into Illinois. There will be a
threat for gusts up to 50KTS, hail, and isolated tornadoes at
KCPS. There will also be MVFR/IFR ceilings and visibilities with
it. MVFR visibilities and ceilings will also occur at KUIN and
KCOU before moving out later this evening. Then dry and VFR
conditions are expected at all of the terminals by 06Z.
SPECIFICS FOR KSTL:
Thunderstorms will move east of the terminal by 01Z. Dry and VFR
conditions expected by 06Z. Southerly winds will gust to around
20KTS at times trough the end of the period.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flash Flood Watch until midnight CDT tonight for Audrain MO-
Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-
Gasconade MO-Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln
MO-Madison MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO-
Osage MO-Pike MO-Ralls MO-Reynolds MO-Saint Charles MO-
Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte
Genevieve MO-Shelby MO-Warren MO-Washington MO.
IL...Flash Flood Watch until midnight CDT tonight for Adams IL-Bond
IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-
Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-
Montgomery IL-Pike IL-Randolph IL-Saint Clair IL-Washington
IL.
&&
$$
WFO LSX