Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/21/19
Area Forecast Discussion
National Weather Service Bismarck ND
923 PM CDT Sat Jul 20 2019
.UPDATE...
Issued at 921 PM CDT Sat Jul 20 2019
The forecast for tonight remains in good shape. Blended latest
observations to hourly forecast elements for this update. Still on
track for increasing chances for precipitation overnight.
UPDATE
Issued at 614 PM CDT Sat Jul 20 2019
Main change for tonight and into Sunday morning was to increase
POPs a bit as a strong S/WV trough swings across the Northern
Plains. Models are nearly in sync with each other with QPF
placement and timing. This change resulted in likely shower
mention across the southwest and far south central late tonight
through the Sunday AM hours. Will keep thunder wording as a
`chance` with scattered activity expected. Otherwise, the forecast
for tonight remains in good shape.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 123 PM CDT Sat Jul 20 2019
The main forecast issue in the short term period will be shower
and thunderstorms chances on Sunday, and daytime highs Sunday.
Latest satellite imagery shows sunny skies across western and
central North Dakota. There was some shower activity over southern
portions of Saskatchewan and Manitoba that may yet sneak across
the border later this afternoon or early evening. Think this will
be very isolated in nature and latest RAP soundings show
instability is pretty much capped above 10-12K ft so if anything
we could see a brief shower or sprinkle. Current shower activity
will be moving into a drier environment as the approach the ND
border.
A closed upper level low currently located over far northern
Idaho will move east across Montana tonight and is forecast to be
over northeast Montana by 12 UTC Sunday, and will move east along
the International border into northwest Minnesota by late Sunday
afternoon. The upper low weakens through this entire period.
However, the low itself, and a strong compact upper level jet
rotating around the base of the low will produce scattered showers
and possibly some isolated mainly afternoon thunderstorms.
The most likely area for precipitation early Sunday will be the
far southwest and south central, which will be under the right
entrance region of the aforementioned jet. Lighter precipitation
will be confined to near the International border, near the mid-
upper level circulation.
With daytime heating, we should see some marginal CAPE of around
500-800 J/kg, enough to support a few thunderstorms. Possibly from
around Williston and Minot southeast to Bismarck and Jamestown,
with lesser chances over southwest North Dakota. Shear is quite
strong earlier in the day but diminishes quickly by the afternoon,
so at this time severe weather is not anticipated.
The increased cloud cover with this upper level system will result
in high temperatures generally in the low to mid 70s on Sunday.
Lingering convection over the south central will diminish Sunday
evening, then mostly clear conditions late with overnight lows
mainly in the 50s.
.LONG TERM...(Sunday night through Saturday)
Issued at 123 PM CDT Sat Jul 20 2019
Dry with warming temperatures highlight the extended forecast
period.
Monday through Wednesday will see the development of a large
downstream h500 trough east of the Mississippi Valley, with an
upstream h500 ridge over Montana/Idaho. This pattern will bring
broad subsidence to the region and maintain dry weather for the
northern plains through Wednesday. We expect a slow warming trend
also during this period as the ridge axis slides east, from the
70s to around 80 on Monday, to the lower to middle 80s Tuesday, to
the 80s to around 90 Wednesday and Thursday. Another cold front
is expected to arrive on Thursday night and Friday bringing a bit
cooler air and scattered thunderstorms to the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 614 PM CDT Sat Jul 20 2019
VFR conditions are expected through the forecast period. We will
see showers and a few thunderstorms move into southwest North
Dakota early Sunday morning and spread east and slightly north.
This continues Sunday afternoon central and east. Will keep VCTS
out of the terminal forecasts for now due to their low
predictability. Will continue to carry a VCSH for those terminals
likely to see some rain.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...NH
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
756 PM MDT Sat Jul 20 2019
.MESOSCALE UPDATE...
Issued at 756 PM MDT Sat Jul 20 2019
We cancelled the Severe Thunderstorm Watch for Laramie County
given instability is dropping and diminished risk for getting
stronger updrafts. We will leave PoPs in the 50 percent or so
range given scattered showers moving in from the west. Also will
raise PoPs a bit for the Chugwater and Wheatland areas next couple
of hours. Otherwise...raised PoPs a small bit farther east into
the Nebraska Panhandle as this area of showers and isolated
thunderstorms moves east late this evening and overnight.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 232 PM MDT Sat Jul 20 2019
Latest satellite loop was showing some towering cumulus developing
over the Laramie Range. However, the bulk of the convection is
currently along the Colorado Front Range. The Colorado Front Range
does not appear to be as capped as our forecast area today. Low
clouds have been fairly stout this afternoon due to CINH values
(200-300j/kg) after the passage of the frontal boundary earlier
this morning. Therefore, we are thinking that this convection
developing over the Laramie Range may weaken a bit as it pushes
east into the capped region during the next hour or so. However,
as the afternoon wears on, the cap should begin to weaken
resulting in better upscale growth. The latest HRRR guidance was
showing the convection being delayed from previous runs. This may
be a result of it underdoing the cap. The NAM depicted this cap
being a little stronger today and keeps most of the convection
along the Laramie Range and mostly west of Cheyenne. However,
during the last hour or so, we have seen a bit more thinning of
the clouds which is indicative of the cap trying to erode. SPC
just issued a watch for Laramie county through 11pm, but at this
point we believe that the best threat for this convection will be
between 6pm and 9pm with the main threat being large hail, due to
it being more elevated.
Later tonight we will most likely see low clouds/patchy fog
develop along and east of the Laramie Range, due to copious
amounts of low level moisture in place. In fact, we may have some
dense fog along the foothills and I-80 summit.
Another frontal boundary is progged to move through the area on
Sunday. Tough to say how deep this boundary will be, but the
moisture will continue be quite deep. Therefore, one cannot rule
out more thunderstorm development along the Laramie Range.
.LONG TERM...(Monday night through Friday)
Issued at 257 AM MDT Sat Jul 20 2019
The extended forecast period will be characterized by a typical mid-
July weather pattern across the central Rockies, w/ quasi-zonal flow
aloft on the northern fringe of broad & flat ridging anchored across
the southwestern CONUS. Numerous mid-level disturbances are expected
to traverse the flow, but in general we can anticipate daily chances
for convection across southeast WY and the western NE Panhandle thru
much of the week, mainly in the afternoons & evenings. Any risks for
severe storms will depend on the timing of individual waves, but the
potential will exist for parts of the area next week. Otherwise, the
general outlook features afternoon highs in the 80s (perhaps low 90s
in the Platte River Valley), and light winds each day.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 756 PM MDT Sat Jul 20 2019
Will keep mention of showers going for Laramie and Cheyenne, with
a showers or thunder vicinity farther east into the Nebraska
Panhandle. Brought in a period of IFR/LIFR ceilings with MVFR
ceilings to most of the Panhandle late tonight into tomorrow
morning given favorable moisture and wind profiles.
&&
.FIRE WEATHER...
Issued at 232 PM MDT Sat Jul 20 2019
Fire weather conditions will be quite minimal this weekend, due
higher daytime humidities. However, if we do receive a lightning
start we may have some potential for gusty northeast winds
resulting in larger spread. Drier conditions are anticipated next
week. This combined with afternoon thunderstorms may result in the
potential for any start to become more explosive.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...JG
SHORT TERM...REC
LONG TERM...CLH
AVIATION...JG
FIRE WEATHER...REC
Area Forecast Discussion
National Weather Service Grand Junction CO
549 PM MDT Sat Jul 20 2019
.SHORT TERM...(Tonight through Sunday night)
Issued at 306 PM MDT Sat Jul 20 2019
A weak shortwave, that brought some early morning thunder to the
region, continues to move across Colorado at this hour bringing
more showers and storms to the San Juans and areas along the
Continental Divide. A few stray returns are showing up for the
Grand Mesa and Moffat county so bumped up PoPs a bit to account
for this. Later shifts will need to keep an eye on this convection
and bump up PoPs, if appropriate. The NAMNEST and HRRR are both
handling this convection fairly well and have all showers and
storms ending by 8PM. As peak heating ends, and the upper level
support shifts to the front range, it follows that convection will
die so forecast follows suit. Winds will become more northerly,
for the most part, which will usher in some drier, and cooler,
air.
A drier day is in the forecast on Sunday as PWATs lower. Light
westerly flow is expected aloft with light west to southwest flow
at the surface. An isolated shower or storm can not be completely
ruled out along the divide given a bit of remaining instability to
the east, however any showers will diminish quickly before sunset.
Expect similar high temperatures across the western slope on
Sunday as were seen on Saturday.
.LONG TERM...(Monday through Saturday)
Issued at 306 PM MDT Sat Jul 20 2019
A large amplitude area of high pressure will be centered over our
CWA Monday and persist through much of the week. Subsidence aloft
will cap most convection as well as decreased moisture though a
stray shower or storm may be possible along the highest peaks of
the Continental Divide for Monday and Tuesday. While we remain
mostly dry, models continue to indicate a stream of moisture
moving up from the south but only reaching Arizona and New Mexico
through midweek. Wednesday onwards, this moisture looks to get
entrained in the anticyclonic flow and as a weak wave drifts
across the northern tier states, this moisture finally moves into
our area. Mid to long term models have been fairly consistent
showing an uptick in convection and rainfall Wednesday through
Saturday. While the moisture tap isn`t as apparent, some hints of
it remain. Expecting most of the convection to be recycled
moisture from the initial push. Temperatures will start out fairly
warm and from midweek onwards, increased clouds and precip will
drop daytime highs a few degrees.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 541 PM MDT Sat Jul 20 2019
Showers and thunderstorms will diminish in intensity through the
evening in northern and central Colorado. HDN, EGE, RIL and
possibly ASE may see a few more brief bouts of rain with some
thunder before things die down around sunset. CIG and VIS will
remain VFR, however an isolated heavier storm could briefly
reduce HDN and EGE to MVFR or break ILS CIG thresholds. Expect
clearing overnight with VFR at at all terminals throughout the day
on Sunday.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...TGR/MAC
LONG TERM...TGR
AVIATION...MAC
Area Forecast Discussion
National Weather Service Lincoln IL
737 PM CDT Sat Jul 20 2019
.UPDATE...
Issued at 737 PM CDT Sat Jul 20 2019
Had to make some significant updates to the forecast for the
western CWA for tonight. MCS across Iowa continues to grow, with
storms riding along the earlier mentioned outflow boundary. Latest
radar imagery shows the line of storms starting to cross the
Missouri border, and is likely to clip the western CWA in a
couple hours. Severe thunderstorm watch was recently issued from
about Peoria-Petersburg westward to account for this possibility.
The boundary itself is now edging into the far northern CWA, and
should provide a significant cooldown as it makes it further into
the area.
In terms of other headlines, the northern half of the Excessive
Heat Warning was allowed to expire at 7 pm. The southern half
remains in effect through Sunday, though as previously mentioned,
there is considerable uncertainty with the portion north of I-70.
Will defer to the overnight shift for any changes after the
evening models arrive.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 328 PM CDT Sat Jul 20 2019
A well-defined outflow boundary generated by a cluster of
convection that tracked from northern Iowa to the
Illinois/Wisconsin border is sinking southward this
afternoon...with 20z/3pm satellite/radar imagery showing it
extending from north of Moline to near Omaha. A few thunderstorm
cells have developed across northeast Iowa over the past couple
of hours; however, the remainder of the boundary is inactive.
With a well-capped airmass to the south characterized by a maximum
warm layer temp of 23C at 850mb, think additional development is
unlikely. As a result, will carry dry conditions across the board
through the evening hours. Additional convection will develop on
the nose of a low-level jet across central/eastern Iowa later this
evening...with this activity gradually developing southward into
the northern KILX CWA overnight. Model solutions vary, but a clear
slowing trend has been noted on successive runs of the HRRR
indicating storms may not arrive in the Peoria area until dawn
Sunday. Have scaled back PoPs accordingly...with likely limited to
locations along/northwest of a Rushville to Minonk line well
after midnight.
The consensus of CAMs suggests the early morning convection will
tend to dissipate north of the I-72 corridor Sunday morning, with
perhaps little re-development until late afternoon across the SE
CWA. Based on good model agreement, have carried likely PoPs
along/northwest of a Rushville to Minonk line through early
morning, then along/southeast of I-70 after 21z as storms fire
along the prevailing outflow boundary from the morning convection.
Due to cloud cover and scattered showers/storms, temperatures
will be considerably cooler on Sunday...with highs remaining in
the 80s across the northern half of the area. Given expected
cooling, have dropped McLean, Logan, and DeWitt counties from the
Excessive Heat Warning on Sunday. If current trends continue,
additional counties will need to be dropped as well...with 100
plus heat index values limited to locations along/south of I-70.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 328 PM CDT Sat Jul 20 2019
The outflow generated convection will exit the SE CWA by early
Sunday evening; however, additional scattered activity will be
possible Sunday night into Monday morning as the trailing upper
short-wave tracks through the region. Once this feature and its
associated cold front pass, all solutions point to deep N/NW flow
and a period of below normal temps for much of next week. In fact,
the latest MEX guidance suggests highs struggling to reach 80
degrees Monday through Wednesday...with overnight lows dipping
into the upper 50s and lower 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 624 PM CDT Sat Jul 20 2019
Quiet in the very short term, but some challenges with wind shifts
and convective chances further into the evening. Latest surface
obs and radar show a well defined wind shift dropping southeast
toward KGBG. Time-of-arrival tool would suggest it reaching KPIA
toward 04-05Z if it keeps on the current track. Meanwhile,
thunderstorms across central Iowa have been moving southeast
toward the western extension of the boundary. Most of the high-res
models aren`t handling that very well, though the GFS is close and
hints at an arrival at KPIA around mid to late evening. Have added
a mention of VCSH there beginning 04Z and moved up the TEMPO MVFR
period as well. Elsewhere, have kept the mentions more vague
(VCTS/VCSH) for now, with some adjustments in time. By late Sunday
morning, winds will be shifting toward the north as a cold front
pushes through, which should mark an end to the rain chances.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 7 PM CDT Sunday for ILZ044>046-
049>057-061>063-066>068-071>073.
&&
$$
UPDATE...Geelhart
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Melbourne FL
905 PM EDT Sat Jul 20 2019
.DISCUSSION...
Diurnal convection has concentrated over the west FL Peninsula this
evng...over east central FL it has all but burned itself except for
isold shras/tsras over west Okeechobee county. Latest RAP40
analysis shows the H100-H70 Bermuda Ridge axis bisecting the FL
Peninsula from E/NE to W/SW...generating 5-10KTS of S/SE flow acrs
the CWA. Low/mid lvl moisture is on the modest side with H100-H70
mean RH values btwn 70-75pct, H85-H50 avg dewpoint depressions btwn
5-7C. Dynamic support is weak with upstream mid lvl vort/omega
fields and upr lvl divergence fields largely flat...strong pockets
of these fields are noted over the west central and northeast
peninsula, but are assocd with lingering diurnal convection and will
diminish once these storms dissipate.
With the mean H100-H70 lyr as weak as it is, modest low lvl
moisture, and negligible mid/upr lvl support, tsras over land seem
too low to mention. The HRRR outperformed the 6KM WRF and it keeps
the CWA more or less dry. Update will limit areal precip to the
Treasure Coast, and only a slgt chc at that.
&&
.AVIATION...Thru 22/00Z.
Sfc Winds: Thu 21/04Z...E/SE 4-7KTS bcmg vrbl AOB 3KTS. Btwn 21/12Z-
21/15Z...bcmg S/SE 5-8KTS. Btwn 21/15Z-21/18Z...coastal sites bcmg
E/SE 8-12KTS. Btwn 21/18Z-21/21Z...KMCO/KSFB/KISM bcmg E/SE 6-
10KTS...KLEE bcmg W/SW 6-10KTS.
Vsbys/WX/Cigs: Thru 21/12Z...E of KVRB-KOBE slgt chc MVFR shras.
Btwn 21/12Z-21/16Z...coastal sites slgt chc MVFR shras/IFR tsras.
Aft 21/16Z...chc MVFR shras/IFR tsras all sites.
&&
.MARINE...
Favorable boating conds overnight as the lcl Atlc remains directly
under the Bermuda Ridge axis. Light to gentle SErly breeze with
seas AOB 2FT. Scattered showers/isold tstms south of the Cape.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Bragaw/Sedlock
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
800 PM EDT Sat Jul 20 2019
.UPDATE...Latest RAP model has Atlantic high pressure stretching
west across much of the Gulf of Mexico...with an axis through
north-central FL through Sun. This will maintain abundant
moisture...with model PWAT values around 2 inches and a
prevailing southeasterly lower level flow. Although winds shift
to onshore in Sun afternoon sea breezes. Sun is expected to be
similar to today - sunny to mostly sunny in the morning then
increasing clouds as showers and thunderstorms form mainly inland
early afternoon and increase and congregate along the Gulf coast
mid to late afternoon.
The strong to severe thunderstorms of this afternoon are now
winding down and slipping out over the Gulf and should exit
coastal areas between 8 and 9 pm. However cloudiness and mostly
light rain/showers will continue a bit later for some
locations...clearing out by midnight. Overall the forecasts look
good but will make minor near term adjustments to better
refection ongoing conditions.
&&
.AVIATION...
21/00Z TAFs. Afternoon convection has just about cleared all the
terminals but will keep VCNTY remarks TIL 02-03Z from SRQ
northward. Anticipate TSRA with PSBL MVFR/LCL IFR AFT 18Z. Winds
become VRBL/easterly for overnight then pick up during Sun as
they shift to SE then S or SW.
&&
.MARINE...
Prevailing southeast winds...except shifting to onshore an an
afternoon sea breeze...at 10 knots or less with seas 2 feet or
less for the rest of the weekend. Main concern will be
thunderstorms with locally higher winds and seas. High pressure
currently across north-central FL settles down over south FL
early next week with a southwest to west flow pattern setting up.
&&
.Preliminary Point Temps/PoPs...
TPA 76 91 76 91 / 30 40 30 40
FMY 75 91 75 91 / 20 50 40 50
GIF 75 93 74 93 / 30 60 10 60
SRQ 75 91 75 91 / 30 30 40 40
BKV 73 92 72 92 / 30 40 20 40
SPG 76 91 76 91 / 30 30 40 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...09/Rude
UPPER AIR...27/Shiveley
DECISION SUPPORT...13/Oglesby
Area Forecast Discussion
National Weather Service Tucson AZ
841 PM MST Sat Jul 20 2019
.SYNOPSIS...High pressure and warm temperatures aloft will limit
thunderstorm development this weekend with just a few storms in the
White Mountains and near the International Border. Increased
moisture and a more favorable flow should result in an increase in
thunderstorm coverage Monday and Tuesday before some drier air moves
in around Wednesday and Thursday with reduced thunderstorm chances.
&&
.DISCUSSION...For those of you in Tucson experiencing thunderstorm
withdrawal, don`t look at the 21/00Z sounding. It`s not a pretty
sight. PW is down around 1.1" without even a sliver of instability.
That being said, some very impressive thunderstorm complexes
developed this afternoon/evening in northern Sonora. This was the
result of an inverted trough working through the Gulf of California
and moisture should be increasing across our area due to these
features. Dew points near Yuma are back into the 60s. Looking closer
to home, it wasn`t a total shutout as a handful of storms developed
and hugged the International Border in Santa Cruz County, but no
gauges measured more than a few hundredths. Not expecting to see any
activity overnight and tomorrow should favor our southern border yet
again. For additional details about improving rain chances next
week, please see the previous discussion below.
&&
.AVIATION...Valid through 22/06Z.
SCT-BKN clouds 12k-18k ft MSL this evening mainly along the
International Border. Cloud cover will diminish overnight before SCT-
BKN decks return Sunday afternoon, with isolated -TSRA/-SHRA south
of KTUS. Surface winds generally less than 12 kts through the
period, favoring WLY-NWLY direction Sunday afternoon with gusts up
to 20 kts. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Expect gusty afternoon northwest winds on Sunday
across the Upper Gila River Valley. 20-foot winds elsewhere will
generally be under 15 mph. The general trend of reduced shower and
thunderstorm activity continues this weekend, with isolated cells
along the International Border and across the White Mountains.
Scattered to numerous thunderstorms are expected Monday afternoon
and evening over much of southeastern Arizona. Broad thunderstorm
coverage remains on Tuesday, decreasing by the middle of the week.
&&
.PREV DISCUSSION...Another low grade monsoon day with below average
moisture for late July. Precipitable water values around 75 to 80
percent of normals at 1.1 to 1.2 inches, but much deeper moisture is
not far away. 1.5 inches in far northern Sonora with 1.8 inches as
far north as the central Gulf and Hermosillo. For today we`ll have
to settle for mainly border storms.
We`re seeing some really good signals that will change things by
late Sunday into Monday. First of all we`re seeing the start of a
surge through the lower western deserts with Yuma dew points jumping
back into the middle 50s (up 20 degrees over the past 24 hours).
KYUX wind profile shows it`s just seeping in at this point with only
5 to 10 kts up to 5k feet. Storms are organizing quite nicely just
south of the border with strong outflows pushing deep into our area
on the HRRR ensembles this evening. The easterly impulse pushing
from the Mexican coast into the southern half of the Gulf of
California should help push the intensity of the surge over the next
36 hours. This alone would indicate a strong upturn in activity, but
the best thunderstorm days for our corner of the state also engage
an easterly moisture source. I like the latest NAEFS mean integrated
WV transport with a push from southwest New Mexico and northern
Chihuahua Monday and Monday night. GEFS plumes suggest at least 1.45
inches precipitable water by Monday afternoon, with operational GFS
as high as 1.6 inches. NCEP SREF plumes argue for for a ML CAPE only
in the 800-1k range, and H5 theta-e values are a tad high, but
vigorous southerly outflow is likely from initial storm formation
Monday afternoon. Interesting to note effective vertical wind shear
in the 25-30kt range on SREF plumes as well. The main story for the
lower deserts may end up being a strong chance at deep outflow from
the Mogollon Rim as well for Monday afternoon and evening. That
would put prime time for Pima and Pinal county valley locations
after 5 PM. Dust could end up being a concern.
Tuesday would likely be a recovery day if the Monday forecast works
out. We`ll see on that. We will still have plenty of boundary layer
moisture to recycle the second half of next week, but are unlikely
to maintain a deep fetch of moisture with an easterly component to
our mid level flow periodically drying out (with limited Gulf of
Mexico influence). However, with the high center finally in a
position where it wobbles back and forth overhead to northwest to
northeast of us, the overall trend will be better.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Howlett
Prev Discussion...Meyer/Pawlak
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