Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/05/18
Area Forecast Discussion
National Weather Service La Crosse WI
659 PM CDT Wed Jul 4 2018
.UPDATE...
Issued at 659 PM CDT Wed Jul 4 2018
The severe weather threat had exited the area for this evening.
Some rises are possible on areas streams as heavy rainfall from
storms today makes its way into the river systems. Additional
storms are possible later tonight mainly south of Interstate 90
but any severe weather should stay south of the area.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 317 PM CDT Wed Jul 4 2018
Main focus is on short term convective potential. Storms have been
slowly increasing this afternoon in the vicinity of a convectively
generated MCV over southern MN and northenr IA and remnant outflow
boundary farther north and east. Ample instability is in place with
RAP analyses showing MLCAPE of 2500 to 3500 J/kg from southeast MN
into northeast IA and western WI ahead of the rain-cooled outflow
air. 0-6 km and 0-3 km shear are lacking with the stronger flow
displaced well north. However, given the instability and the
boundaries/MCV to help aid organization, a window for a few strong
to severe storms will exist this afternoon into early evening. Still
expect damaging winds and heavy rain to be the primary hazards given
very warm temps aloft, but some hail is possible.
Given this evolution, confidence is decreasing in strong or severe
storms later this evening and tonight with the approach of the main
cold front and upper shortwave trough sliding off to the north in
the wake of the afternoon storms. Did keeps some lower end
shower/storm chances going, but it is possible that many areas will
end up dry for evening activities.
Will trim the northern and western edge of the Heat Advisory but keep
it going farther to the south and east at this time.
Drier and cooler air will work in on Thursday behind the front on
Thursday although a few showers or storms could persist into the
morning.
.LONG TERM...(Thursday night through Wednesday)
Issued at 317 PM CDT Wed Jul 4 2018
Much quieter weather is expected late this week into the weekend
with broad surface through mid-level ridging in place. A shortwave
trough passing across southern Canada Sunday and Sunday night may
drag a surface boundary south into the area, but right now
confidence in showers/storms is low. Otherwise, surface ridging
will remain in place into early and middle of next week with
southerly flow helping to bring warmer air back into the area.
Temps will gradually warm from the upper 70s to mid 80s Friday and
Saturday into the 80s to perhaps low 90s by the middle of next
week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 659 PM CDT Wed Jul 4 2018
VFR conditions are expected at the TAF sites. Isolated showers and
possibly a thunderstorm cannot be ruled out tonight but the bulk
of this activity should stay south of the TAF sites.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
UPDATE...Wetenkamp
SHORT TERM...JM
LONG TERM...JM
AVIATION...Wetenkamp
Area Forecast Discussion
National Weather Service Burlington VT
754 PM EDT Wed Jul 4 2018
.SYNOPSIS...
Hot weather will continue through Thursday as strong high
pressure remains across the area. The chances of showers and
thunderstorms increase later Thursday afternoon into Friday
morning as a cold front crosses the area. Behind this front,
cooler, more seasonal temperatures are expected for the upcoming
weekend.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
As of 650 PM EDT Wednesday...Another hot day across the North
Country with BTV hitting 95 degrees and atop Mount Mansfield
tying their all time record high temp of 84 degrees again.
However, dewpoints currently in the mid 50s to lower 60s has
resulted in cooler heat index values in most areas, but have
jumped into the l/m 60s per the 7 PM, with a 70 dewpoint at mss.
As sfc high pres shifts to our east tonight, south/southwest
winds just off the deck at 10 to 15 knots will help advect
deeper moisture back into the North Country overnight. Soundings
show bl dewpoints increasing quickly after sunset tonight into
the 60s with some values approaching 70 degrees across the SLV
and CPV by sunrise on Thursday. The airmass will become very
muggy again with heat advisory looking good for Thursday. Latest
rap does show some potential for mixing of slightly drier air
aloft toward the sfc, which should keep values below the
readings experienced on Sunday. Otherwise, a very quiet and warm
night expected with lows ranging from the l/m 60s mountain
valleys to lower 70s cpv/slv.
Agree with previous forecaster thinking with regards to
convection on Thursday aftn/evening. Looks like a classic pulse
environment with high cape (2000 j/kg) and weak shear (0 to 6
km <25 knots) and limited forcing. Also, deep dry layer on
soundings btwn 800mb and 500mb might limit areal coverage of
convection. However, deep layer mixing thru 750mb with steep
lapse rates and dcape values around 1300 j/kg, would support the
threat for an isolated svr with damaging winds as the primary
hazard, in the stronger more robust updrafts. SPC day 2 has
most of our cwa in marginal risk, which looks reasonable given
the expected pre- storm convective environment.
Previous discussion below:
Southwesterly return flow will develop over the region tonight
as high pressure overhead shifts eastward and off the Atlantic
Coast. This will allow us to tap into a warmer, higher humidity
air mass currently over the Ohio River Valley. Thus, expect
temperatures tonight to be quite a bit warmer than last night.
The Champlain and Saint Lawrence Valleys will remain in the low
to mid 70s, while the remainder of the CWA will bottom out in
the mid to upper 60s overnight. As we pull in moisture in
addition to the warmer air to our southwest, expect air to feel
increasingly muggy overnight into tomorrow.
As low pressure over central Canada shifts eastward Thursday, the
pressure gradient will increase over New England, allowing for
southwesterly flow to strengthen. Warm air/moisture advection
will continue through the day ahead of an approaching cold front
pushing east through the Great Lakes Region. Expect clouds to
spread over the region from west to east through the day.
Despite the cloud cover however, Thursday will be very hot and
muggy. Temperatures will once again be in the low 90s in the
Champlain and Saint Lawrence Valleys and upper 80s elsewhere.
Dewpoints will be higher than today however, so heat indices
will be in the upper 90s up to 100 during the afternoon hours. A
heat advisory is in effect from noon to 8 PM Thursday for the
Saint Lawrence Valley, western Champlain Valley of New York, and
central and northern Vermont.
During the day Thursday, some moderate instability will build in
the atmosphere (MUCAPE values progged in excess of 2,000 J/kg),
so could see some convective showers develop during the day as
heights slowly fall ahead of the approaching trough. Forcing
will be limited however, so not expecting widespread convection.
Nonetheless, any showers that do develop will have plenty of
moisture (Forecast PW values > 1.8") and warm air to work with,
so could produce locally heavy rainfall and some gusty winds.
As we transition to the overnight hours Thursday night, expect any
convective showers/thunderstorms that have developed to weaken as we
lose instability and the atmosphere becomes capped. However,
attention quickly then turns to the approaching cold front,
which will trigger more rain showers as it pushes through from
west to east overnight. While we will have lost the better
daytime instability, still will likely have some elevated
instability to work with, so a few thunderstorms are not out of
the question in the overnight hours. 0-6km bulk shear values
between 20 and 40 kts could allow for some more organized
storms to develop along the front, with the primary threats
being locally heavy rainfall and some gusty winds. Once the
front pushes through, we`ll finally usher in long awaited
cooler, drier air from Canada, finally marking the end of this
summer heat wave that will remain in the record books for a
quite some time.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 331 PM EDT Wednesday...Relief from our heat wave
finally arrives on Friday as a cold front crosses the North Country.
This front will bisect the region from northeast to southwest Friday
morning, separating the warm humid air to the south and cooler,
drier air to the north. Showers and possible thunderstorms will
likely be ongoing across eastern VT Friday morning ahead of the
front, but these will quickly be shunted to the south and east by
the afternoon as the front pushes into souther/eastern New England.
Clearing will take place post-front, though expect we`ll see
scattered cumulus lingering into the afternoon. Winds will turn to
the northwest and become breezy behind the front, ushering in a much
more comfortable airmass. Highs will be in the lower to mid 70s in
the mountains, while the wider valleys will likely be in the upper
70s to around 80. Skies will clear out overnight, and with dewpoints
in the 40s and 50s, expect it will be a very refreshing night after
the prolonged heat and humidity.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 331 PM EDT Wednesday...It`s shaping up to be a
beautiful weekend as high pressure crests directly over the area.
This will lead to lots of sunshine and mainly light winds. Saturday
will be the cooler of the two days with highs in the 70s areawide,
while Sunday`s temperatures will top out around 80 in most
locations. The next chance for rain arrives Monday into Monday night
as a weak trough/frontal boundary sinks south out of Canada. This
feature will hang around at least through Tuesday, keeping the
threat of showers/thunderstorms in the forecast. Wednesday is a
little more questionable as the GFS shows a ridge building in while
the ECMWF has an upper low dipping right over the North Country.
Have gone with just a slight chance of showers for now. Temperatures
through the middle of next week will be a bit above normal with
slightly muggier conditions than over the weekend, but not anything
like what we`ve seen this week.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Through 00Z Friday...Mainly VFR conditions through the period
for most TAF sites...exceptions will be at KSLK/KMPV/KRUT where
nearly calm winds at the surface and moisture advection
overnight will provide conditions conducive for some MVFR fog
development between 07-11z. Thursday winds will turn out of the
south between 10-15 kt with gusts upwards of 20 kt later in the
afternoon at all sites except KPBG which should remain with a SE
lake breeze throughout much of the day. Afternoon thunderstorms
may be possible across the area Thursday so have mention of
VCSH at all TAF sites mainly after 18z. A cold front approaches
from the west toward the end of this TAF period.
Outlook...
Thursday Night: VFR. Likely SHRA, Chance TSRA.
Friday: Mainly VFR, with local MVFR possible. Chance SHRA, Chance
TSRA.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. Slight chance SHRA.
&&
.CLIMATE...
Max Temp Records July 4th through 5th:
Date KBTV KMPV K1V4 KMSS KPBG KSLK
07/04 98|1911 92|1983 100|1911 95|1949 95|1955 94|1921
07/05 98|1911 90|2010 99|1911 93|1949 97|2010 95|1928
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Heat Advisory from noon to 8 PM EDT Thursday for VTZ001>012-
016>019.
NY...Heat Advisory from noon to 8 PM EDT Thursday for NYZ026>028-
035-087.
&&
$$
SYNOPSIS...RSD
NEAR TERM...RSD/Taber
SHORT TERM...Hastings
LONG TERM...Hastings
AVIATION...LaRocca/RSD/Taber
CLIMATE...WFO BTV
Area Forecast Discussion
National Weather Service Caribou ME
914 PM EDT Wed Jul 4 2018
.SYNOPSIS...
A ridge of high pressure builds over the region on Thursday. A
strong cold front will approach Thursday night and cross the
area Friday morning. High pressure will bring cooler and drier
air into the region late Friday into Saturday.
&&
.NEAR TERM /THROUGH THURSDAY/...
9:14 pm update: One lone shower developed near Eagle Lake
shortly after 8 pm, and it fell apart by 9 pm just west of
Washburn. The shower never looked too impressive on radar with
little reflectivity aloft. There are a few healthier looking
showers showing up on MRMS just along and just west of the Saint
Lawrence River. As the region remains on the periphery of a
strong upper ridge, an isolated shower or thunderstorm could
develop in situ or move into the area from the west/northwest.
The best chance of a shower or thunderstorm the remainder of the
night will be across northern Aroostook County, and mainly from
03-06Z. Made some tweaks to the forecast for the remainder of
the night based on the latest observations and radar.
Previous discussion:
Humidity will be on the increase tonight into Thursday w/yet
another hot day expected for Thursday. But before that, there is
some hint at the potential for a couple of tstms this evening.
Beach Hazard Statement will expire at 8 PM.
The latest suite of mesoscale guidance including the RAP and
HRRR have backed up on any convection until much later this
afternoon into the evening. Dewpoints have been slow to increase
so far today, but are still progged to increase over the next
3-4 hrs. The latest sfc analysis showed the higher
dewpoints(mid/upper 60s) to the sw. As winds turn to a more ssw
direction this evening and overnight, this will push those
higher dewpoints ne. Low/mid level lapse rates will steepen and
some moisture does look like it gets advected into the region.
0-6KM shear of 30 kts and inverted v-type sounding lends support
for some strong downdrafts if storms can get going. Will keep
mention of strong wind gusts for any storms. Activity should be
done by midnight w/clearing. Some patchy fog is expected as
well. Overnight lows will be in the 60s.
For Thursday, heat index values are forecast to increase into
the mid and possibly upper 90s, mainly away from the Bangor and
Downeast region due to the ssw wind. Upper ridge looks like it
builds over the region. The 12Z NAM/GFS show this well. Decided
to go w/a Heat Advisory for the Central Maine Highlands and the
Millinocket and Houlton region. Further n and w, readings look
to be a bit cooler attm. This will need to be assessed by the
later crews if the advisory needs to be expanded further n.
Daytime temps are expected to be in the low to mid 90s w/the
exception of the Downeast coast. As far as precip goes, it
should be dry until later Thursday night. More on this in the
medium range below.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Thursday night will be warm and steamy ahead of an approaching
cold front from Quebec. Lows Thursday night will likely not get
out of the lower 70s in most places. The warm temperatures and
dew points in the upper 60s to near 70 will result in a rough
sleeping night for those without air conditioning. Coastal
stratus is likely to be an issue as well, as southerly winds
transport higher dew point air across the Gulf of Maine,
resulting in low clouds and patchy fog for the coast. Expect a
few showers and thunderstorms to develop across northwest Maine
after midnight in advance of the approaching cold front.
The cold front will cross far Northern Aroostook County and
the St. John Valley shortly after daybreak Friday and then
continue to push southeast off the down east coast by late
afternoon. Shower and thunderstorms are expected to accompany
the passage of the front on Friday. The early timing of the
front will not be favorable for widespread severe weather.
However, the best chance for any stronger storms would be
across down east, do to the somewhat later timing of the front.
Will not include any enhanced wording at this point and let
midnight crew re-evaluate the threat. Did mention the chance
for some heavier rain in any thunderstorms for central and
downeast with pwat/s close to two inches. The cold front will be
push offshore by sunset Friday. A much drier and cooler air
mass is expected to overspread the region in the wake of the
frontal passage Friday night making for much more comfortable
sleeping weather. Lows by Saturday morning are expected to range
from the upper 40s to near 50 north and lower 50s downeast.
A large ridge of high pressure will build east from the Great
Lakes region on Saturday. Expect partly/mainly sunny skies on
Saturday. Highs will be in the low to mid 70s which is close to
normal for this time of year.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
After the brief heat relief on Saturday, ridging between systems
will again send temperatures above normal Sunday and Monday.
Without the persistence of a large, nearly CONUS-wide ridge
deflecting systems north, the heat won`t be as stagnant.
Next system to impact Maine will be Monday afternoon overnight
into Tuesday. 12Z GFS continues with a cold front solution
exiting off the coast Tuesday morning. The CMC tries to
replicate this but then develops a more progressive closed low
compared to the ECMWF. Will keep these solutions in mind by
lingering chance PoPs over northern areas. A lot of interaction
occurs off the east coast depending how the front exits the
region, which will have impacts on how progressive the early to
mid-week system will be.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
NEAR TERM: VFR conditions are expected through Thursday at the
terminals.
SHORT TERM: VFR conditions are expected at the Aroostook County
terminals Thursday evening. Scattered showers and thunderstorms
are expected to develop across far northwest Aroostook County
after midnight. Moisture advecting in off the coastal waters
will result in low clouds and patchy fog with IFR or lower
conditions late Thursday night at KBGR/KBHB. Widespread showers
and the chance for thunderstorms can be expected on Friday as a
cold front crosses the region. The front will reach KFVE shortly
after daybreak and clear the down east coast late Friday
afternoon. MVFR or lower conditions are possible in any heavier
showers or thunderstorms on Friday, especially at KBGR/KBHB.
Clearing skies and VFR conditions will develop from northwest to
southeast in the wake of the frontal passage. VFR conditions are
expected are expected Saturday through Tuesday.
&&
.MARINE...
NEAR TERM: No headlines expected into Thursday. Winds/seas will
pick up to 10-15 kts by Thursday afternoon as winds go ssw. Seas
are forecast to build to heights of 3-4 ft by late in the day on
Thursday.
SHORT TERM: Winds/seas could begin to approach SCA levels as we go
into Thursday night and Friday in the southwest flow ahead of
the approaching cold front. Visibility will be reduced to 1 to
3 NM in areas of fog Thursday night and in areas of fog,
showers, and thunderstorms on Friday. Winds/seas will then
remain below advisory criteria much of the remainder of the long
term.
&&
.CLIMATE...
The high temperature this afternoon at Caribou was 90 degrees.
This was the first 90 degree day since June 11, 2017. On average,
Caribou averages one 90 degree day every other year; however,
many years there are none, and some have a few to several days
with a high of 90 degrees or warmer. The high of 90 this afternoon
fell shy of the record high of 92 degrees, set in 1983.
At Bangor, the high temperature this afternoon was 94 degrees.
This was the warmest temperature observed since July 22, 2011.
The high of 94 degrees today fell shy of the record high of 99
degrees, set in 1949. On average Bangor averages 4 days with a
high of 90 or above each year. The last time there was a year
without a 90 degree day was in 2014; and 1995 holds the top
honors with a total of 23 days with a high of 90 or above.
The record highs for tomorrow, 7/5 are:
Caribou: 92F, set in 1983
Bangor: 95F, set in 1935
Houlton: 93F, set in 1983 and again in 2000
Millinocket: 92F, set in 1983
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Heat Advisory from 1 PM to 7 PM EDT Thursday for MEZ005-006-
011-015-016-031-032.
MARINE...None.
&&
$$
Near Term...CB/Hewitt
Short Term...Duda
Long Term...Cornwell/Duda
Aviation...CB/Hewitt/Duda
Marine...CB/Hewitt/Duda
Climate...CB
Area Forecast Discussion
National Weather Service State College PA
1110 PM EDT Wed Jul 4 2018
.SYNOPSIS...
Heat and humidity will continue at least until a cold front
pushes southeast through the region Thursday night and early
Friday. Cooler and less humid air moving in behind the cold
front will last all weekend.
&&
.NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...
Almost all precip is gone from the CWA, and skies are even
mainly clear in the NErn third. IR shows cloud tops cooling in
wrn PA, but some ltg still going near Warren Co and weak showers
also trying to push in from the west as outflow boundary
impinges upon the wrn mtns. Will adjust PoPs for the recent
trends, with a lingering sprinkle possible over much of the area
overnight. PWATs remain very high, so it might not take much
lift to make a cell grow. For the most part, though, it is
pretty stable.
Prev...
Quite the active afternoon is finally showing signs of calming
down. Earlier showers and thunderstorms organized around a weak
low level boundary under a mid level low. The storms were fueled
by a moisture rich environment with PWATs in excess of 2 inches
common over almost the entire CWA.
The rain is most organized from Schuylkill and southern
Columbia counties down into the vicinity of Thomasville. The
activity now seems mainly focused around the plethora of outflow
boundaries that have been laid out around the region from the
earlier widespread storms. SPC meso page indicates overall
instability is on the wane as more and more of the area gets
worked over by the rain and comes under the upper cloud
umbrella.
The HRRR just keeps the storms going through midnight which
seems unreliable in such a weakly forced environment. I trimmed
the POPs down expecting activity to continue to follow the usual
diurnal decline in the absences of some sort of strong forcing
mechanism.
Temps tonight will be quite uncomfortable once again, with mins
only dipping into the upper 60s to lower 70s.
&&
.SHORT TERM /7 AM THURSDAY MORNING THROUGH FRIDAY/...
The sfc wind becomes more SWrly in the west for the day on
Thursday and should help to focus some increase in moisture
there.
The lake breeze in the far NW and terrain influences elsewhere
along the Alleghenies should provide focus for convection, along
with random/differential heating and meandering weak outflow
boundaries from the recent convection.
Upper heights slowly lower a few decameters thru the day and
Thursday night as a weak pre- frontal trough moves in from the
NW. So, it should be easier to get more convection going.
The Day2 SVR Outlook from SPC does indicate that slightly
stronger winds aloft on Thurs PM (mainly across northern PA and
into New York State) could support isolated wind damage.
Thursday night looks very disorganized, but could be the time to
include the highest PoPs, at least for the NW half of the CWA.
The front approaches the NW zones around 12Z Fri, and moves
through with some alacrity on Friday morning. All guidance
pushes the front thru all but the far SE by the middle of the
afternoon. Therefore, it would be tough to see strong convection
without the benefit of daytime/peak heating for all but the SE
on Friday. But, the PoPs should be OK at categorical for the
morning and early aftn for the central and srn zones.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
*Cooler and refreshingly less humid air will arrive this
weekend and may last into Monday.
The cold front should be well to our south at 00Z Sat. Drier and
There is some question as to how much upper ridging can rebound
into early next week. Relief from the relentlessly hot/humid
weather will arrive this weekend as cooler and less humid air
sweeps southeast from Canada.
Showers may drop in from the Great Lakes by the mid-week period,
but Sat-Mon looks dry with seasonable temps, and welcome surface
dewpoints in the 40s and 50s.
PWAT values plummet to an impressive minus 2-3 sigma Saturday
morning, then stay in the minus 1-2 sigma range into early
Monday as an area of high pressure (1024-1028 mb on the GEFS)
drifts SE from the upper midwest and becomes located over the
state Sunday morning.
In contrast to the fans and AC units we had constantly running
throughout the week, this weekend and early next week will give
us the opportunity to get out the blankets (if you choose to
sleep with the windows open) Friday night through Sunday night,
as temps slide well into the 40s for mins across the northern
mtns, and upper 40s and 50s elsewhere.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Area of rain and thunderstorms that plagued the north and
central airfields this afternoon has sunk into the southeast.
KMDT and KLNS will see -SHRA and VCTS for the next few hours
before everything diminishes. Since all areas saw heavy
rainfall today, added BR in the overnight period.
Similar set up tomorrow as today so used persistence from last
night and early today for the extended portion of the forecast.
.Outlook...
Fri...Shower or thunderstorm impacts possible, mainly in the
morning.
Sat-Mon...No sig wx expected.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Dangelo/La Corte
NEAR TERM...Dangelo/La Corte
SHORT TERM...Dangelo/Lambert
LONG TERM...Lambert/Tyburski
AVIATION...Tyburski
Area Forecast Discussion
National Weather Service Dodge City KS
505 PM CDT Wed Jul 4 2018
...Updated Aviation...
.SHORT TERM...(This evening through Thursday)
Issued at 155 PM CDT Wed Jul 4 2018
Vis satellite shows some weak cumulus buildups across SE Colorado.
Have only slight pops near the Colorado border to account if an isolated
storm should develop in this region during the late afternoon and slowly
drift to the state border. Confidence on this is not particularly high
as mid level winds are very weak. Additionally, some of the meso models
like the ARW and NMMB were showing early morning convection as the main
trof swings thru just to our north. Did have some slight pops in there
but decided to get rid of these as confidence is just not high enough.
Recent versions of the HRRR show dry conditions prevailing through
the overnight. Even if those models were partially correct, coverage
would be extremely isolated and most areas will remain completely dry
through the short term period. Otherwise, lows tonight should be in
the upper 60s to lower 70s.
For tomorrow, we will see slightly cooler highs with values in the upper
80s to around 90F. Some of the models do mix out more and thus have
higher temps, however, there might be lingering mid level clouds that
could reduce mixing slightly. Otherwise, storms tomorrow evening will
be isolated once again with much of the activity remaining across Colorado.
It is too early at this time to get rid of pops completely, particularly
across the west and north zones where these areas are in closer proximity
to whatever does develop.
.LONG TERM...(Thursday night through Wednesday)
Issued at 155 PM CDT Wed Jul 4 2018
Isolated thunderstorms are still possible, however, with low certainty
for Friday and into the weekend. Again, not expecting widespread storms.
Near normal temperatures will continue. The ridge starts to build over
the Plains next business week with highs increasing. Values should
trend to slightly above normal by the end of the extended period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 505 PM CDT Wed Jul 4 2018
VFR will continue to prevail through this TAF cycle. Isolated
convection near the CO/KS border is expected to have no impacts on
the airports this evening. Gusty SE winds will diminish after
00z Thu, with light SE winds prevailing overnight. Thunderstorms
are expected tonight in Nebraska, and some models such as the
latest HRRR and the 12z ECMWF suggests some of this activity will
build southward and approach HYS late tonight (09-12z Thu). Have
very little confidence in these solutions, but included a VCTS/CB
mention at HYS around 09z. Also kept TSRA out of the TAFs through
Thursday afternoon, although some isolated activity will likely
exist at peak heating. Otherwise, a cumulus field and light SE
winds are expected Thursday afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 70 91 69 90 / 10 20 10 20
GCK 69 91 68 89 / 10 20 20 20
EHA 66 90 67 90 / 10 20 20 10
LBL 68 92 68 90 / 10 10 10 10
HYS 70 91 69 89 / 20 20 30 40
P28 74 93 71 92 / 0 10 10 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Sugden
LONG TERM...Sugden
AVIATION...Turner
Area Forecast Discussion
National Weather Service Sioux Falls SD
1057 PM CDT Wed Jul 4 2018
.SHORT TERM...(This evening through Thursday)
Issued at 259 PM CDT Wed Jul 4 2018
The 4th of July has certainly been an interesting day weatherwise.
Early morning MCV tracking across the CWA forced severe convection
over the eastern portions of the forecast area, with continued weak
synoptic lift trailing across the Missouri River valley for much of
the day. The end result has been a general stabilization of the
atmosphere north of this convection, along with cooler temperatures
than expected. Generally, model guidance has proven fairly useless
today with poor initializations across the board, with only the RAP
and the afternoon runs of the HRRR providing some value.
This afternoon and tonight: The greatest severe weather risks are
going to be focused along or south of the Missouri River this
afternoon, as a shortwave tracks northward into the area. Latest
mesoanalysis suggests MLCAPE values approaching 2000 J/KG south of
the CWA, but overall marginal shear. Now that the MCV has moved
far enough to the east, we should begin to see 850 mb flow focus
itself across north central Nebraska, where new convection should
form quickly along a convergence axis between Oneill and Ainsworth.
If short term guidance is correct, this should relieve some of the
pressure on ongoing convection in Charles Mix and Bon Homme
counties. A small scale MCS cluster may develop and move across
northern Nebraska into the evening. Further north, not as
impressed with rain or convection risks through the evening
festivities. It`s certainly possible the developed stratiform
region of convection further south could clip the I-90 areas, but
those chances are lower now. The only other area to watch will be
with a frontal boundary dropping southward this evening. Convergence
is minimal, but could see an isolated shower or storm form on this
boundary as it moves south this evening.
While most models are NOT indicating this potential, I do see
some concern for redevelopment of convection after midnight south
of I- 90 as the 850 mb boundary remains planted in the area. There
could be just enough convergence and enhancement of the LLJ to
produce a linger band of moderate rains between Sioux Falls and
Sioux City. Will bump up the QPF amounts in this area, but must
stress this is low confidence on occurring.
Thursday-Thursday night: High pressure will bring cooler
temperatures and drier air southward on Thursday. The 850 MB
boundary will fail to clear the CWA however, and this certainly
could bring the potential for a few daybreak showers and storms into
Friday morning. Later shifts may need to add this potential into
the forecast.
.LONG TERM...(Thursday night through Wednesday)
Issued at 259 PM CDT Wed Jul 4 2018
Friday-Sunday: Mid-level height rises will bring an increase in
temperatures and humidity back into the region for this weekend. A
growing 597DM ridge overhead should suppress convection this
weekend. A lone precipitation chance could present itself late
Sunday evening over northern South Dakota and western Minnesota
along a poorly defined front.
Next week: Medium range guidance seems to suggest that we`ll
continue to grow a mid-level ridge over the region, again keeping
precipitation chances on the lower end. Temperatures will trend
above average, with rather oppressive humidity settling into the
region.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1046 PM CDT Wed Jul 4 2018
Showers may linger through the lower MO River Valley into portions
of northwestern IA during the overnight hours. By mid morning on
Thursday any activity will end across the area with VFR conditions
through the period.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...Dux
LONG TERM...Dux
AVIATION...JM
Area Forecast Discussion
National Weather Service Grand Junction CO
943 PM MDT Wed Jul 4 2018
.UPDATE...
Issued at 943 PM MDT Wed Jul 4 2018
After looking at the 00Z run of the latest HRRR smoke forecast,
have decided to go ahead and include the Highway 82 corridor from
Basalt northwest to just south of Glenwood Springs and the Highway
133 corridor south through Carbondale to the Dense Smoke Advisory
tonight. The Lake Christine Fire grew to over 2300 acres today
and, once the nocturnal inversion sets up tonight, smoke should
settle into those lower elevations.
&&
.SHORT TERM...(Tonight through Thursday night)
Issued at 220 PM MDT Wed Jul 4 2018
Heights will rise through this period as a large upper level high
pressure center shifts from the Ohio Valley to the UT/CO region.
Southerly steering flow on the western periphery of the anti-
cyclone will persist through Thursday, then becoming light and variable
under the center of high pressure Thursday night. Convection is
having a tough time gaining any appreciable depth today so far.
Expect any isolated showers/storms to dissipate quickly with
sunset. Smoke from the 416, Burro and now the Lake Christine
wildfires will affect areas downwind this afternoon, then after
the inversion sets up late this evening, will begin to flow
downvalley. Have issued a Dense Smoke Advisory again for the
Animas River Valley/550 corridor downvalley from the 416 fire
where persistent dense smoke has been a problem each night. Will
have to keep an eye on the Hwy 82 corridor northwest of Basalt for
dense smoke issues if the Lake Christine fire continues to grow.
A subtle vorticity maximum and some increase in precipitable water
Thursday should yield a little better chance of showers/storms in
the afternoon, but focused over the higher terrain of Colorado
from the Divide to the San Juan Mtns.
.LONG TERM...(Friday through Wednesday)
Issued at 220 PM MDT Wed Jul 4 2018
Strong upper level high pressure will remain centered over UT/CO
through Sunday, then models agree on it migrating back to the
Midwest/Mississippi Valley early next week as an upper level
trough moves across the Pac NW and northern Rockies. The big
forecast challenge during this period is figuring out
precipitation chances and coverage. Models are suggesting quite an
increase in precipitable water and instability by Friday. However,
the core of the higher moisture associated with an easterly wave
over the Texas coast today will be suppressed well to our south as
the high pressure aloft sits directly overhead. While it is
possible to see available moisture increase under the high
pressure aloft, it seems reasonable to expect at least a delay of
onset. Models are responding to the higher moisture and CAPE and
increasing coverage of showers/thunderstorms. We are a little
suspect so are not getting too excited yet. However, we will issue
a Special Weather Statement for south of I-70 to address the
possibility of increased thunderstorms. With weak steering flow,
any storms that do develop will be slow-moving and have the
potential to cause flash flooding, especially if over recent burn
scars.
When the high pressure center migrates east next week, flow
between that and the approaching trough will set up a more
reasonable expectation for higher moisture moving over the region
and attendant increase in shower/thunderstorm activity.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 943 PM MDT Wed Jul 4 2018
VFR conditions will prevail at all TAF sites over the next 24
hours. Increased moisture on Thursday will allow for an increase
in mid and high level clouds as well as better shower and
thunderstorm coverage over the Colorado mountains after 18Z.
Outflow winds to 35 knots will be the main impact from these
storms through sunset Thursday evening.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Dense Smoke Advisory until 10 AM MDT Thursday for COZ008-010-019-
022.
UT...None.
&&
$$
UPDATE...MMS
SHORT TERM...BM
LONG TERM...BM
AVIATION...MMS
Area Forecast Discussion
National Weather Service Green Bay WI
1033 PM CDT Wed Jul 4 2018
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Thursday
Issued at 334 PM CDT Wed Jul 4 2018
Scattered thunderstorms have Popped up as expected across much of
the forecast area in a very unstable airmass. Two primary areas of
focus are storms that have developed along the lake breeze over
southern Door County. These storms have been very slow moving
given the very weak vertical wind shear and are being modulated by
thunderstorm outflow and aforementioned lake breeze. Recent radar
trends indicate storms continue to develop along thunderstorm
outflow and are training across the same area over southwest Door
County. Rainfall rates of 1 to 2 inches per hour are likely and
have already received a report of 3 inches southwest of SUE. Have
issued a flood advisory to address this situation.
West of the Fox Valley additional storms have formed along a line
from western Shawano across Menominee into northern Oconto
counties. Again these storms are training along the same general
area but so far rainfall amounts have been less than an inch
locally.
Overall storm coverage will likely increase slightly for the
remainder of the afternoon but they will be generally disorganized
and pulse-like in nature. Storms that are slow moving or training
will definitely be capable of producing a couple inches of rain
in localized areas. Given the amount of instability, a few
updrafts could be strong enough to generate hail up to a half inch
in diameter and perhaps a wind gust to 45 mph. Overall storms
should remain just below severe limits but will be monitoring
closely.
Finally, remnant MCS moving across northcentral Wisconsin is
continuing to weaken. Last few runs of the HRRR support that
trend. However its rain-cooled outflow will likely interact with
storms west of the Fox Valley and lead to an uptick in the
convective coverage and intensity there.
Over southwest Wisconsin another MCS has been strengthening as it
interacts with outflow boundary downstream. These storms have been
the strongest are have the best potential for producing severe
weather. Latest HRRR also suggests these storms should generally
stay south of the forecast area or perhaps clip southwest
Marathon and Wood counties this evening. SPC has retained slight
risk into that area overnight which seems reasonable.
Weak cold front will slowly sag southeast across the forecast
area overnight and will keep chances for showers and storms in the
forecast until Thursday morning. Overall coverage of convection
should begin to wane after sunset. RAP and HRRR suggest could be
a few storms along the boundary over the southern Fox Vally until
about 18 UTC Thursday. Thus maintained chance pops in that
region. By Thursday afternoon somewhat cooler and drier airmass
should slowly infiltrate the area as winds turn northwest begins
the front.
.LONG TERM...Thursday Night Through Wednesday
Issued at 334 PM CDT Wed Jul 4 2018
Medium to long-range models continue to be in very good agreement
on the placement of a strong upper-level high pressure system
across the central Rockies through the weekend, stretching into
the Ohio Valley late in the weekend and early next week. Surface
high pressure will spread over the Great Lakes late in the week
then shift to the east early next week. These systems will bring
quiet weather to the region, along with cooler and much less
humid conditions through Sunday afternoon. The chance for more
active weather looks to arrive late Sunday into early next week as
the upper ridge flattens, heights fall as a shortwave crosses the
northern U.S., and a boundary sags into the region.
Cold front will be well south of the area by Thursday night into
Friday, with surface high pressure working into the western Great
Lakes. It will be much cooler and less humid with slightly below
normal low temps ranging from the lower 50s (a few upper 40s
possible) north to the middle 50s to around 60 in the Fox Valley
and lakeshore. Friday looks to be a very pleasant and comfortable
summer day with plenty of sunshine with highs in the upper 70s to
lower 80s for most spots, except a few degrees cooler near Lake
Michigan. The quiet weather continues into Saturday as the high
pressure slides into Lower Michigan. Humidity levels will increase
slightly, but should still be a pretty comfortable day with highs
in the lower to middle 80s (slightly cooler near the lake).
As the surface high shifts east of the region Saturday night into
Sunday, return flow starts to ramp up across the area. Temps and
dewpoints will continue to slowly creep up, but it doesn`t look to
be as tropical as it was on/around July 4th, with dewpoints only
in the lower to possibly middle 60s and temps in the middle 80s
away from Lake Michigan. Precip chances still look very low as
models show better warm air advection, low level jet, moisture,
and the surface boundary remaining to our northwest. Shower/storm
chances increase as we head into Sunday night and Monday as the
boundary sags south into the area and moisture increases.
Still a little to early to determine how intense/widespread the
shower/storm activity will be, with slight timing differences
impacting if storms can take advantage of peak heating.
Convergence doesn`t look overly impressive with no clear low level
jet pointed in our direction. Setup warrants slight/chance POPs
for now. Precipitable waters over 1.5 inches by Monday afternoon,
so where storms do form, heavy rain will be possible. Dewpoints
climb into the 60s to near 70 on Monday, providing for a pretty
sticky day. Models not in any agreement on how things play out
with the boundary and what arrives mid-week but it looks to remain
very summer-like.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1033 PM CDT Wed Jul 4 2018
Showers and thunderstorms have come to an end across the area
overnight. Recent model runs keep the area dry through the
overnight with some breaks in the clouds. These breaks could cause
some fog with MVFR or IFR conditions given the recent rainfall.
Any fog that forms will dissipate quickly Thursday morning. A
secondary cold front may bring some showers to the area on
Thursday, mainly across the southern TAF sites. However coverage
and confidence is too low to include in this set of TAFs.
Conditions behind this front will clear out from north to south as
high pressure builds in from the west.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....ESB
LONG TERM......Bersch
AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Jacksonville FL
952 PM EDT Wed Jul 4 2018
.UPDATE...
The upper level low is now centered in the Ocala area with the
convection over land waning due to the loss of diurnal heating.
The flow around the system will keep a few light showers moving in
from off the ocean but they shouldn`t progress more that 10 or 20
miles inland. They are small and moving quick so durations will be
quite limited.
&&
.AVIATION...
With respect to the update above will keep VCSH at all fields,
except KGNV, overnight as the showers move in from off the ocean.
Should be no serious visibility or ceiling restriction and
durations will be quite brief. The HRRR continues to indicate an
increase in shower activity after 08:00 utc so have added a few
Tempo groups for that time period, if only because the showers
could be more numerous.
&&
.MARINE...High pressure well northeast of the waters will maintain
an onshore flow through Saturday. A western Atlantic begins to build
south of the waters over the weekend providing a light offshore flow
with afternoon seabreezes near the coast. A weak back door front
will wash out across the waters early next week. Scattered showers
and storms.
Rip Currents: Moderate risk through Thursday due to an onshore flow
and surf/seas nearshore of 2-3 ft.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 72 90 71 91 / 30 40 20 40
SSI 77 87 76 87 / 40 40 30 30
JAX 72 88 73 91 / 30 50 30 40
SGJ 75 87 73 88 / 30 50 30 50
GNV 71 90 72 90 / 40 60 30 60
OCF 71 90 73 89 / 40 70 40 60
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Sandrik/Nelson/Corless
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
655 PM CDT Wed Jul 4 2018
.SHORT TERM... (Through Late Thursday Afternoon)
Issued at 402 PM CDT Wed Jul 4 2018
Isolated diurnally-driven thunderstorms are possible during the heat
of the afternoon. Any SHRA/TSRA which develop should dissipate early
this evening.
Light south to southeast winds are expected through the early
evening hours before winds turn light/variable later tonight. Smoke
from area fireworks displays may struggle to dissipate this evening
due to these low wind speeds as well as little mechanical mixing
overnight; BUFKIT profiles from the RAP and NAM both show very light
winds in the lowest few thousand feet AGL. Winds will become
westerly to northwesterly after daybreak on Thu.
A low pressure system moving through Canada will push a cold front
into the western Great Lakes tonight. This front will continue to
sag southward and then become more zonally oriented on Thu as it
continues to drift southward into MO/IL.
Hot and humid conditions will persist through tomorrow across most
of the area, although parts of northeastern MO and west central IL
could see some relief during the afternoon when clouds and
thunderstorms are expected to develop near the sagging cold front
and/or near a wind shift line ahead of the T/Td discontinuity
associated with the true frontal boundary.
The existing Heat Advisory looks reasonable considering today`s
hot/humid conditions will be followed by little overnight relief and
yet another day of heat/humidity on Thu. Overnight lows tonight
should be in the mid/upper 70s across most of the area, and slightly
warmer highs on Thu will yield heat indices of 105-107 across the
advisory area on Thu. Farther west, slightly lower dew points will
produce slightly lower heat index values of 100-104. Depending on
the extent of cloud cover, the Heat Advisory may need to be expanded
westward for areas near and south of the Missouri River.
Kanofsky
.LONG TERM... (Thursday Night through Next Wednesday)
Issued at 402 PM CDT Wed Jul 4 2018
The cold front should be drifting through Missouri and into central
and southern Illinois Thursday night. The eastern periphery of the
H5 ridge will be over the lower Missouri and middle Mississippi
Valleys Thursday evening. Mid to upper level lapse rates are not
particularly impressive with the upper ridge overhead, but low to
mid level lapse rates are forecast to be between 7-8C/km for a
few hours during the evening resulting in MUCAPE in excess of 2200
J/Kg. CINH values are rather high, so surface based convection
seems unlikely, and this is probably why most of the models really
back off their QPF during the evening. However, am concerned that
the PoPs these lower QPF values yield may not be representative
of the actual precipitation chances. Have therefore bumped the
chance of precip up a bit for most locations on Thursday night.
The front is expected to slow a bit on Friday morning and hang
over southern Missouri/Illinois. This should provide a focus for
additional scattered convection through Friday afternoon.
The mid Mississippi Valley is in store for some spectacular mid-
summer weather this weekend. Medium range guidance continues to
show a sprawling Canadian high moving into the upper Midwest and
Great Lakes region. Below normal highs in the mid 80s are expected
for most of the area each day. Saturday and Sunday morning lows
will be in the lower 60s and even upper 50s.
The upper level ridge will build back over the region early next
week. Temperatures will drift back up into the 90s across most of
the region and humidity levels will increase again as southerly flow
is reestablished over the mid Mississippi Valley. Have some low
PoPs in the forecast as the higher RH moves back into the area, but
at this point timing and coverage is low confidence.
Carney
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 633 PM CDT Wed Jul 4 2018
Mainly dry and VFR conditions are expected at the terminals during
the period. Only exceptions will be this evening when there will
be the possibility for lingering smoke from fireworks. There will
also be an increasing chance for thunderstorms over northern
Missouri and central Illinois into KUIN as a cold front moves
south into the area. Any storm could bring MVFR/possible IFR
conditions and brief downpours. Southerly winds will become light
and variable as the front approaches the area and then shift
northwesterly behind the front.
SPECIFICS FOR KSTL:
Mainly dry and VFR conditions are expected through the period.
Only exception will be this evening when there will be the
possibility for lingering smoke from fireworks. Southerly winds
will turn light and variable this evening but then turn
northwesterly behind a cold front tomorrow.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory until 8 PM CDT this evening for Audrain MO-Boone
MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
Knox MO-Lewis MO-Lincoln MO-Marion MO-Moniteau MO-Monroe MO-
Montgomery MO-Osage MO-Pike MO-Ralls MO-Shelby MO-Warren MO.
Heat Advisory until 8 PM CDT Thursday for Iron MO-Jefferson MO-
Madison MO-Reynolds MO-Saint Charles MO-Saint Francois MO-
Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO-
Washington MO.
IL...Heat Advisory until 8 PM CDT this evening for Adams IL-Brown IL-
Pike IL.
Heat Advisory until 8 PM CDT Thursday for Bond IL-Calhoun IL-
Clinton IL-Fayette IL-Greene IL-Jersey IL-Macoupin IL-
Madison IL-Marion IL-Monroe IL-Montgomery IL-Randolph IL-
Saint Clair IL-Washington IL.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Lubbock TX
639 PM CDT Wed Jul 4 2018
.AVIATION...
Deep easterly flow becoming firmly established with upper ridge
center relocating over the central Rockies and high plains by late
Thursday. An upper impulse in the easterly flow, moving to the
west over the southern Texas Coastal Plains, will steer far to
our south early Thursday. Expect, however, in increase in low
level moisture early Thursday - enough for low clouds - but how
low is uncertain. Latest HRRR continues to indicate a chance for
at least brief IFR ceilings reaching KLBB during the pre-dawn
hours Thursday, but not seeing this on other solutions. Have added
a FEW020 at KLBB for now and keep an eye on trends, updating as
necessary. Otherwise continuing to favor cloud decks just above
MVFR. RMcQueen
&&
.PREV DISCUSSION... /issued 327 PM CDT Wed Jul 4 2018/
DISCUSSION...
A little bit of a welcome cooling will occur after today with
increased chances of precipitation for the weekend.
The mid level moisture plume that has been overhead the past
several days is still not totally scoured out. It will still
provide a slight chance of thunderstorms for the rest of this
afternoon into the early evening with greatest chances across the
extreme southern Texas Panhandle. Some of the cumulus field has
become more agitated and enhanced around the edge of the caprock
from Briscoe into Floyd Counties. Sufficient instability around
500-1000 J/kg under a deeply mixed and warm atmosphere will lead
to high based and unorganized isolated storms as far east as the
edge of the caprock. Stronger storms will exist in eastern New
Mexico and may extend into the extreme southwestern Texas
Panhandle.
An expansive upper level ridge will shift to the north tomorrow
taking with it the remaining portion of the mid level moisture
plume. The center of the ridge will shift farther to the west on
Friday allowing stronger low level moisture advection into West
Texas. This will generally keep temperatures closer to seasonal
averages this weekend. Models continues to depict weak short waves
rotating around the east/southeastern side of the upper ridge
which will provide better chances for thunderstorms this weekend
into early next week. It still remains extremely difficult and
unclear to pin down any time for better chances of precipitation.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
99/99/05
Area Forecast Discussion
National Weather Service Riverton WY
240 PM MDT Wed Jul 4 2018
.SHORT TERM...(This evening through Thursday)
Issued at 240 PM MDT Wed Jul 4 2018
Visible satellite imagery shows cumulus field across the western
mountains and the Great Divide Basin Wednesday afternoon. The
southern Absaroka Range has the best potential for isolated
convection to develop around 3pm/Wed before winding down by
9pm/Thu. Recent runs of the HRRR are trying to develop isolated
convection from the cumulus field over the Great Divide Basin and
bring it northeast through Natrona County. This possibility cannot
be ruled out, but would expect little more than gusty outflow
wind of 30-40 mph. Any jet energy of consequence has pulled away
to the north and a ribbon of CIN is still in place across central
Wyoming. Any weak showers or storms that develop will be
diurnally driven and will dissipate by late Wednesday evening. It
will be mostly clear overnight with the possible exception of
Natrona County. Boundary layer relative humidity along with
easterly upslope flow across the county could lead to the
development of a lower cloud deck early Thursday, generally
between 4am and 10am. 500mb heights will rise Thursday as 600dm
height center sets-up over eastern Colorado/western Kansas. Thus,
it will be warmer Thursday with temperatures at least slightly
above normal. Southeast return flow around high pressure in the
Northern Plains will transport low-level moisture into Johnson and
Natrona counties Thursday. Pseudo-dry line along the east slopes
of the Bighorn Range down to Hiland will separate the higher dew
points of 50-55F from rapidly decreasing dew points west of this
line. The higher dew point air coupled with favorable directional
shear profile should lead to thunderstorms, some possibly strong,
in Johnson and Natrona counties late Thursday afternoon. SPC day
2 outlook now includes this area in a marginal risk for severe
thunderstorms. The higher terrain, especially the Bighorn Range,
would be the likely area for initial convective development around
3-4pm/Thu. There will also be enough mid-level moisture in
southerly flow aloft to initiate weak convection over the central
and northern mountains again Thursday afternoon, similar to
Wednesday.
.LONG TERM...(Thursday night through Wednesday)
Issued at 240 PM MDT Wed Jul 4 2018
South-southwest flow bringing hot and relatively dry air north
across western and central Wyoming will support mainly isolated
showers and thunderstorms over the central and northern mountains
Thursday evening. Then, dry and hot conditions will dominate the
weather Friday with even hotter temperatures on Saturday when much
of the lower elevations east of the Continental Divide could
exceed 100 degrees. There is an outside chance of isolated
thunderstorms across the south Saturday afternoon spreading north
into the western and central mountains on Sunday. Some cooling is
expected Tuesday and Wednesday with isolated mainly afternoon and
evening showers and thunderstorms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday)
Issued at 240 PM MDT Wed Jul 4 2018
VFR conditions expected through 00Z/Friday at all terminals with one
short duration exception. Boundary layer moisture will increase from
the east at KCPR early Thursday in association with return flow
around high pressure in the Northern Plains. This moisture push and
weak upslope flow may very well generate lower ceilings and
localized IFR or MVFR around KCPR between 10Z-16Z/Thu. This would
lead to mountain top obscurations above about 7,000 ft MSL across
Natrona County. Isolated weak convection this evening will be
diurnally driven and end around 03Z/Thu. Mid-level moisture in
southerly flow aloft will provide a similar convective set-up
Thursday with isolated late day showers and storms moving east off
the northern and central mountains.
&&
.FIRE WEATHER...
Issued AT 240 PM MDT Wed Jul 4 2018
A cold front slipped south through central Wyoming early Wednesday.
This will keep fire weather concerns below critical through the
remainder of Wednesday afternoon. Warmer and drier air will
remain in place into the evening hours across zones 277, 278, and
279, but wind speeds will generally be 15 mph or less. Isolated
showers and storms over the central and northern mountains will
likely dissipate as they move east off the mountains. The primary
hazard will be gusty outflow wind of 30 to 40 mph. It will be
warmer across the entire forecast area Thursday as high pressure
takes control over the central Rockies. For the most part,
relative humidity will remain above 15 percent with zones 280 and
281 the most likely locations for wind speeds of 15 to 20 mph.
This wind will be from the southeast and will transport low-level
moisture into these zones. Late day isolated showers and storms
will again form over the central and northern mountains Thursday.
The moist, low-level southeast flow will also produce isolated
showers and storms over zones 280 and 281. Conditions will
continue to trend hotter and drier Friday and Saturday. Not only
may Saturday be the warmest day of the season, but increasing
westerly wind is likely to lead to elevated fire weather
conditions.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CNJ
LONG TERM...Baker
AVIATION...CNJ
FIRE WEATHER...CNJ
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
453 PM MDT Wed Jul 4 2018
.DISCUSSION...(This Evening Through Wednesday)
Issued at 148 PM MDT Wed Jul 4 2018
The latest water vapor images and RAP 500-mb analysis show a
broad ridge extending from the East Coast back to CO/NM. One
short-wave trough/upper low was spinning over Saskatchewan/
Manitoba, with a larger upper low off the Pacific Northwest Coast.
A trailing cold front from the southern Canada low has pushed
through all the CWA, but moist and unstable air was lingering over
south-central SD where showers/storms were occurring. The rest of
the CWA was relatively dry with northwest surface flow bringing
dew points in the lower 40s to upper 50s. Other than south-central
SD, the rest of the CWA was mostly sunny, except for some
stratocumulus over the central/western Black Hills. The showers/
storms over south-central SD should move eastward by 03z as the
cold front continues to move southeast.
On the large scale, the upper high/ridge will build westward to near
the four-corners area by late Friday, fostering a very warm pattern
through the weekend. Saturday should be the hottest day with highs
well into the 90s. Rainfall chances will be minimal, but a few
thunderstorms will be possible at times as subtle/weak short-wave
troughs rotate around the ridge. This will be aided by evapotran-
spiration given the anomalous greenness and surface moisture from
the rainfall over the past several weeks, allowing for humidity
and CAPE to build up. The ridge is forecast to flatten some next
week, which may be associated with a slightly better chance for
thunderstorms.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Thursday Evening)
Issued At 453 PM MDT Wed Jul 4 2018
VFR conditions are expected through the period.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION...Bunkers
AVIATION...JC