Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/03/16
Area Forecast Discussion
National Weather Service La Crosse WI
642 PM CDT FRI SEP 2 2016
.SHORT TERM...(This evening through Saturday)
Issued at 245 PM CDT Fri Sep 2 2016
Latest 19z surface analysis shows high pressure centered over
northern Wisconsin into northern Michigan. This is producing mostly
sunny skies and some diurnal cumulus clouds across the forecast
area per latest visible satellite imagery.
Tonight into Saturday...Surface/upper level ridge over the Great
Lakes Region will continue to dominate the forecast area. Light
winds and clear skies will result in patchy to areas of fog in the
Wisconsin river valley and favored locations in central Wisconsin.
The 02.12z GFS/NAM and 02.15z RAP hint at wind speeds of 15 to 20
knots at or above 300 feet. This will inhibit fog formation in the
Mississippi river and its tributaries. With surface/upper level
ridge ridge in control Saturday...the forecast area is expected to
remain dry...along with seasonable temperatures.
.LONG TERM...(Saturday night through Friday)
Issued at 245 PM CDT Fri Sep 2 2016
Sunday into Monday...Upper level ridge flattens out and
southwesterly flow aloft develops over the High Plains and the
Upper Midwest. The forecast area should remain dry Sunday...as the
02.12z GFS/NAM/ECMWF suggest lift/forcing/moisture convergence in
association with shortwave troughs embedded in the southwesterly
flow to be west of the forecast area. As upper level trough
deepens over the Rocky Mountains and surface front moves slowly
southeast Sunday night into Monday...moisture transport/convergence
begins to increase after 06z Monday across the far
northwest/western sections of the forecast area...with the
stronger low level jet/moisture transport/convergence west of the
forecast area. Have continued chances of showers/thunderstorms
mainly across western/northwest sections of the forecast area.
During this time frame...severe threat looks low as the higher
instability remains west of the forecast area and the
deterministic models show 0-3km shear around 20 knots.
The main concerns Monday night through Friday revolve around
thunderstorm chances, particularly Tuesday through Wednesday.
An upper-level longwave trough parked over the western CONUS will
place the Upper Midwest under southwesterly flow through Wednesday
night. The first in a series of shortwaves will pass by to our
northwest Monday night. Associated shower and thunderstorm activity
may sneak into our northern areas. A frontal boundary is progged to
set up from the Central High Plains extending into the Great Lakes
region on Tuesday. This quasi-stationary boundary should be the
focus for shower and thunderstorm development Tuesday and Wednesday,
aided by a strong low-level jet, ample moisture transport, and
subtle disturbances moving through aloft. Strong to severe storms
may be possible Tuesday into Wednesday, especially if the best shear
and instability line up with each other. Another concern is a
prolonged heavy rain potential, which will be dependent on how far
southeast the frontal boundary drifts on Wednesday. The upper-level
trough finally kicks eastward out of the northern Rockies by
Thursday morning, with the ECMWF continuing to be the faster
solution. This should clear our area of precipitation chances by
Thursday evening, if not sooner.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 642 PM CDT Fri Sep 2 2016
VFR conditions will be the rule at KRST/KLSE through the period.
While skies will become mostly clear overnight, expect increasing
southerly flow, especially atop the nocturnal boundary layer.
These stronger winds will likely prohibit widespread valley fog
from developing. Some thermal based cumulus are possible by
Saturday afternoon in the 3000 to 4000 ft agl layer. Light
southeast wind this evening and overnight will increase and shift
to the south by Saturday afternoon.
&&
.ARX Watches/Warnings/Advisories...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...DTJ
LONG TERM...DTJ/MH
AVIATION...ROGERS
Area Forecast Discussion
National Weather Service Bismarck ND
849 PM CDT FRI SEP 2 2016
.UPDATE...
Issued at 849 PM CDT Fri Sep 2 2016
Latest surface analysis places a cold front from near Regina south
to Wolf Point, Montana and snaking southwest into Billings, Montana.
An area of showers and isolated thunderstorms developing along/ahead
of the front, just south of Wolf Point, per latest HRRR forecast
will continue to move northeast into Williams/DivideCounties from
03z-07z. Chance to Likely pops have been inserted here. Main
threat is wind gusts. Within the last hour or so near Miles City,
Montana, wind gusts reached 54 mph with this area of precipitation.
Downdraft cape remains high at 1400 to 1500 j/kg, however, surface
dewpoints not as dry in northwestern ND as they were in eastern
Montana prior to the cold front. Nonetheless, will be monitoring
potentially strong winds as this precipitation area pushes through.
Once this area of precipitation exits into Canada by 08z, the rest
of the night appears dry. Next chance of precipitation arrives in
northwest ND mid morning Saturday.
UPDATE Issued at 534 PM CDT Fri Sep 2 2016
Have decided to cancel the wind advisory as sustained winds and
gusts are not meeting criteria. It will remain breezy this evening
and winds may briefly be enhanced central ND into the James River
Valley as mixing stronger winds aloft down to the surface as a
weak line of showers moves through. Currently, the showers are aligned
from southwest Sioux County, to Burleigh county, and northeast to
Pierce County.
Otherwise, farther west, a cumulus field continues to develop over
eastern Montana, ahead of a cold front. Per latest HRRR, an area
of showers and thunderstorms are expected to grown this evening. The
latest HRRR shows a line of showers and thunderstorms developing
between now and 03z/10PM CDT Friday, then crossing into our
western border thereafter. The HRRR indicates that northwest ND
would be the favored area for precipitation and have adjusted
pops in this region. Rest of forecast remains on track.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 1238 PM CDT Fri Sep 2 2016
The main focus for the short term is winds and precipitation
chances.
Afternoon winds so far have remained just below Wind Advisory
criteria, with sustained speeds around 25 mph and gusts around or just
less than 40 mph. Wind speeds will diminish somewhat this evening
as diurnal heating and mixing ends. However, a tight pressure
gradient will remain over the eastern half of North Dakota and a
low level jet may intensify late tonight across east central North
Dakota. This could keep gusty winds around 30 mph through the
overnight hours for portions of the James Valley.
So far today precipitation has been rather scattered and weak.
Very little if any precipitation is reaching the ground across
western North Dakota. Latest runs of short term guidance continue
to trend dryer for this afternoon and evening and the 18z special
sounding shows a rather substantial cap. However, an upper level
shortwave trough is expected to swing through later this afternoon
and evening. This could enhance the potential for precipitation
later this afternoon and evening across central and eastern North
Dakota and will therefore keep a mention of a slight chance of
light rain showers in the forecast. There have been a few
lightning strikes from time to time and with forecast
showalter indices around -5 will keep a mention of thunderstorms
in the forecast as well.
.LONG TERM...(Saturday night through Friday)
Issued at 1238 PM CDT Fri Sep 2 2016
Possible heavy rain and severe weather will highlight the
extended forecast.
A slow moving upper level trough will impact the Northern Plains
this weekend into early next week. A moisture plume will push
precipitable water values above the 99th percentile and will
support the possibility for heavy rainfall across central and
eastern North Dakota Sunday afternoon and Sunday night. At the
same time cape and shear could be substantial enough to produce
some strong thunderstorms with large hail and damaging winds
Sunday afternoon and evening. Some uncertainty on how much surface
heating will occur if ongoing showers and thunderstorms limit the
afternoon heating, but at this time it seems plausible that some
portions of southern North Dakota will be under the threat for
strong thunderstorms.
By Monday the cold front will bring cooler and more stable air to
the region. More widespread showers are expected across the
northwest North Dakota where the strongest winds aloft will be
found.
Somewhat cooler weather is expected Tuesday through Thursday with
a chance for scattered showers and isolated thunderstorms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 534 PM CDT Fri Sep 2 2016
A cold front will slowly move into western ND after 06z, and then
continues into the central terminals Saturday afternoon, before
stalling prior to getting into KJMS. Hence, ahead of the cold
front Friday night, expect a vcsh/vcts at KISN and possibly KDIK,
then shifting into KMOT/KBIS after 18z Saturday. Vfr cigs/vsbys
still expected with the frontal passage.
&&
.BIS Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...AC/KS
Area Forecast Discussion
National Weather Service Spokane WA
446 PM PDT Fri Sep 2 2016
.SYNOPSIS...
An autumn like weather pattern is expected for the Labor Day
weekend and into next week. Cool temperatures will privily with
scattered showers and possibly a few thunderstorms from time
mainly concentrated over the mountains. No big warm up is
expected through the end of next week.
&&
.DISCUSSION...
Tonight through Sunday...Satellite reveals a cool upper level
trough settling in over the forecast area this afternoon. The
initial cold front associated with this trough passed through last
night...and now radar suggests a secondary cold front over the
Cascades this afternoon with a line of showers set to break out
into the basin...with popcorn showers and a few thunderstorms
forming ahead of it over the cool but moist and unstable air mass
ahead of it over eastern Washington. It will take much of this
evening for these showers and isolated thunderstorms to work
through the forecast area...with just about any location being
subject to a brief shower or storm this evening...but probably the
greatest concentration will occur over the northeast Washington
mountains and the north Idaho panhandle. A few lingering showers
will likely persist over these orographically favorable regions
well into the night. As is often the case with these transiting
troughs skies will probably clear out over the basin overnight and
become more scattered over the northern mountains. This will allow
some radiational cooling by dawn with some patchy fog developing
in the northern valleys and some chilly and damp morning low
temperatures to start the holiday weekend.
Saturday through Sunday will be dominated by the continued
presence of the upper level trough with high confidence of
continued cooler than normal temperatures...however
precipitation-wise the weekend may not be too bad for outdoor
recreation. Models are in reasonably good agreement in
aggressively digging the base of the trough deep into Oregon. This
will probably leave the forecast area in a sort of col region
where there will be insufficient dynamic support to trigger
showers over the basin...with scattered hit-and-miss showers and a
few thunderstorms concentrated over the mountain peaks ringing the
basin. The uncertainty lays with the Sunday afternoon time frame
where a deformation region over western Montana may bleed over the
Bitterroots and bring an elevated chance of showers to the Idaho
Panhandle.
So...for barbecues in the basin this weekend there are no real
worries. For camping in the mountains pack warm cloths and rain
gear but expect substantial dry periods with some sunbreaks each
day. /Fugazzi
Monday through Friday:
The region is expected to remain in a trough wave pattern for the
week ahead. The troughs are not expected to be as strong as over
the weekend and will mainly impact the Northern counties and Idaho
Panhandle. The first trough will be on Monday. This is expected
to be the strongest of the shortwave troughs. The models are
indicating strongest instability in extreme Northeast WA and the
Northern ID Panhandle by Monday afternoon. This could trigger an
isolated lightning strike in the that region. The Columbia Basin
will remain relatively dry while most mountain terrain could
experience some rain showers. This will carry on through Tuesday.
By Wednesday the trough flattens and a zonal flow is expected to
produce some breezy conditions in along the Cascades. By Thursday,
another trough will drop into the region from the Northwest and
bring another round of showers to the higher terrain in the
region. Models are indicating potential thunderstorms for the
Idaho Panhandle. Temperatures for the region will in the 70s range
for highs and the 40s for lows. Some of the extreme North areas
could see lows in the mid 30s. /JDC
&&
.AVIATION...
00Z TAFS: Showers and isold t-storms will impact Ern WA and N ID
through 3-5Z then dry conditions will return. Most activity will
focus along a frontal boundary that currently stretches from
Republic to Moses Lake and 00z TAFS utilized HRRR and other CAM
models to time this line through Spokane-Cd`A. Brief wind gusts
near 25 mph could also accompany this line. Pullman and Lewiston
should mainly be brushed by the southern tail of this line of
convection. After 12z...we will be looking for a very small threat
of stratus developing over the Palouse and possibly into the
Spokane-Cd`A Area. Conditions look less favorable then last night
when rain fell in the Basin so will only carry few at this time.
/sb
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 46 68 48 69 48 70 / 50 10 10 10 10 20
Coeur d`Alene 45 67 44 69 45 69 / 50 10 10 10 20 20
Pullman 41 67 41 69 42 69 / 20 10 10 10 20 10
Lewiston 50 74 49 74 51 74 / 20 10 10 10 20 10
Colville 40 71 40 73 42 72 / 60 20 20 10 30 30
Sandpoint 42 67 40 68 42 66 / 60 20 10 20 30 30
Kellogg 43 65 41 65 42 66 / 40 10 10 30 40 40
Moses Lake 44 73 46 75 47 74 / 20 0 10 10 0 0
Wenatchee 51 71 51 73 52 74 / 20 10 10 10 0 0
Omak 46 74 46 76 47 75 / 30 10 20 20 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Las Vegas NV
838 PM PDT FRI SEP 2 2016
.SYNOPSIS...A few more showers and thunderstorms will be possible
over northern Mohave County Saturday. Otherwise, the region will be
dry at least through Tuesday. Temperatures will fall to about five
degrees below normal Sunday and Monday before rising slightly later
in the week.
&&
.UPDATE...Based on radar and satellite trends as well as the latest
HRRR and RAP runs, showers/thunderstorms are done for the night in
Mohave County. The forecast updated accordingly. -Harrison-
&&
.PREV DISCUSSION...
317 PM PDT FRI SEP 2 2016
.SHORT TERM...through Monday night. Thunderstorms over Mohave County
have been less numerous today than yesterday, as expected. This
trend should continue tomorrow as drier air makes slow eastward
progress through our area in response to the trough moving slowly
into the West Coast. As the trough makes further progress on Sunday,
dry air will take over the entire CWA, and temperatures will also
drop to about five degrees below normal. Another concern will be
winds through the weekend. Conditions will be close to Red Flag
Warning criteria, but it appears that any stations which meet
criteria will be isolated in space and time and not widespread.
Winds should relax a bit on Monday, with temperatures remaining
about five degrees below normal.
.LONG TERM...Tuesday through Friday.
Tuesday onward will see the longwave trough generally begin to lift
out and flatten out over the central US. Expect temperatures to
gradually recover a few degrees as this happens. Shortwaves passing
by to the north could yield breezy afternoons once again mid-week.
The focus then turns toward the tropics. Both the GFS and euro
develop a tropical system and bring it by the mouth of the Gulf of
Baja. This is favorable to initiate a poleward surge of tropical
moisture that would reach the area sometime in the Wednesday and
Thursday timeframe. However, the models begin to diverge after
Tuesday. The Euro keeps the tropical system more intact as it tracks
up the Baja, but the GFS, not so much.
At this time, models are still inconsistent run-to-run, but there is
subtle agreement that the best chances of thunderstorms, are they to
happen, is Mohave county late in the week. However, any
precipitation chances are contingent on the track of a tropical
system that is days away from even developing. In other words,
confidence cannot get much lower despite model indications.
&&
.AVIATION...For McCarran...Gusty south to southwesterly winds will
relax overnight, potentially favoring more of a southeast direction
before a period of light and variable in the morning. Gusty
southwest winds will develop once again by tomorrow afternoon.
For the rest of southern Nevada...northwest Arizona...and southeast
California...Not a lot of change expected for the region through
tomorrow. Winds will relax overnight with gusty south to
southwesterly winds picking back up once again tomorrow.
&&
.SPOTTER INFORMATION STATEMENT...Thunderstorms are expected to
primarily occur over Mohave County today. Spotters are encouraged to
report significant weather according to standard operating
procedures.
&&
$$
Morgan/Steele
For more forecast information...see us on our webpage:
http://weather.gov/lasvegas or follow us on Facebook and Twitter
Area Forecast Discussion
National Weather Service Dodge City KS
409 AM CDT SAT SEP 3 2016
...Updated Short Term and Long Term Sections...
.SHORT TERM...(Today and tonight)
Issued at 408 AM CDT Sat Sep 3 2016
Water vapor satellite and RAP analysis show an elongated mid
tropospheric trough axis extending from eastern SD down into western
KS. This is in advance of a much larger scale west-southwest flow
pattern extending all the way to the Pacific Coast of California.
The persistent west-southwest flow aloft will keep the lower
tropospheric lee trough in place across easterN Colorado. As far as
precipitation goes, convergence and warm advection in the 850-700mb
layer provided enough upward vertical motion to support a narrow
axis of weak convection along roughly a Dighton to Garden City to
Liberal line (as of 0850z). This axis of shower/thunderstorm
activity will advance east through the morning hours, and we will
keep some 20 POPs in for this scattered convective activity.
Surface winds will ramp up today as the pressure gradient tightens
with deepening lee trough (sub-1000mb). Gradient will support
strongest winds generally west of Highway 283 to the Colorado border
where sustained 20 knots should be common this afternoon. Boundary
layer convergence along the lee trough axis will be in the
traditional location of Baca County, CO into far east central CO. We
will have some slight chance POPs along the CO border from late
afternoon into the early evening. We will have some Chance POPs,
around 30 percent, later in the evening from roughly Scott City to
Wakeeney to Hays where a more organized MCS may track across
northwest KS, perhaps clipping these areas.
.LONG TERM...(Sunday through Friday)
Issued at 408 AM CDT Sat Sep 3 2016
A mean longwave trough will be the story across the western CONUS
through much of this period. This will keep western Kansas in a
general southwest flow pattern aloft, keeping the leeside trough in
the lower levels a prevailing feature through the holiday weekend
into much of next week. Downslope of the higher terrain of New
Mexico will lead to increased capping in the 850-700mb layer, which
will make it more difficult to get thunderstorm activity much of
this period. Nevertheless, a few isolated to widely scattered
thunderstorms will be possible late afternoon and evening in
traditional lee trough convergence zones in far west central/far
southwest KS Sunday, Monday, and even into Tuesday. By Wednesday,
there are indications from the ECMWF and GFS that a fairly
formidable wave/jet streak will finally come out into the High
Plains, which would advance the lee trough across western Kansas,
pushing the precipitation chances farther east. Still though, the
best upper jet and baroclinic zone supporting larger scale upward
vertical motion will be up into Nebraska, so it is hard to really
find much to get too excited about regarding widespread thunderstorm
activity with a lot of precipitation. We will not likely have a
decent front push through our region again until at the very end of
this forecast period (Sep 9-10).
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1231 AM CDT Sat Sep 3 2016
Should see the development of MVFR stratus around 09z as low level
moisture continues to push north into western KS. Stratus layer
should be concentrated in the 1500 to 2500 foot layer, so IFR
category is not expected, however MVFR will be likely through
around 15 or 16Z. A leeside trough will continue to deepen across
eastern Colorado in the afternoon, leading to breezy if not windy
conditions. GCK terminal will see strongest winds with sustained
around 20 knots in the mid to late afternoon, including some gusts
to 30 knots.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 84 66 89 70 / 20 10 10 10
GCK 86 66 92 69 / 20 20 20 10
EHA 89 65 91 67 / 20 30 20 10
LBL 87 66 91 70 / 20 10 20 10
HYS 84 66 89 71 / 20 40 10 10
P28 85 68 88 71 / 10 10 10 10
&&
.DDC Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Umscheid
AREA FORECAST DISCUSSION
National Weather Service New Orleans LA
342 AM CDT SAT SEP 3 2016
.SHORT TERM...
Drier air has filtered in to northern portions of the forecast
area as a weak frontal boundary sagged south towards the Gulf of
Mexico. Currently the front appears to be located from south of
Lafayette to Lake Pontchartrain to north of Mobile. There is about
a 7 to 10 degree difference in dewpoints between north and south
of the boundary. Thinking that this will be a large contributing
factor to where convection initiates this afternoon. Thus believe
that the GFS and ECMWF indicate thunderstorms developing too far
north in the CWA while the HRRR shows storms more correlated to
where the higher surface moisture is. So have adjusted today`s
pops accordingly with near 60% from a HUM to MSY to GPT line and
barely 20% from BTR to MCB to capture the more isolated convection
expected there. Glancing at model soundings, an inverted-V becomes
apparent during the afternoon hours along with dry air aloft
which would suggest the potential for microbursts. A few storms
could produce damaging winds in the strong to maybe severe range.
Otherwise, highs should be running in the low to mid 90s with New
Orleans and Hammond being the hotspots.
.LONG TERM...
The upper trough to the east will be quickly lifting northeast
while while a maritime upper level ridge builds over the gulf
south over the next few days. This will promote moisture return to
the whole forecast area and subsequently higher chance for
rainfall. Expect a typical diurnal pattern with convection
initiating late morning and thunderstorms carrying over into the
afternoon and early evening hours. Greatest coverage at this time
appears to be Sunday and Labor day at around 30 to 50%. The ridge
will begin to translate into a more continental ridge and then
start to shield the CWA from convection as the center moves close
to the northern coast of the Gulf of Mexico.
MEFFER
&&
.AVIATION... VFR conditions should remain through the morning hours
at all terminals. Better chances for sh/ts will exist along and
south of a line from Donaldsonville, LA to Poplarville, MS. Tempo
groups will be used for these areas. To the north of that line,
thunderstorms will still be possible but not as numerous. TAF
updates for these areas should suffice. Microburst potential will be
higher today but since this is a conditional field, it will mean
that a thunderstorm will have to develop nearby or over the field to
receive strong or damaging wind speeds.
&&
.MARINE...
Light winds and low seas expected for the remainder of this forecast
package. Nocturnal sh/ts will continue as well through the week.
&&
.DECISION SUPPORT...
DSS code: Green.
Deployed: None.
Activation: None.
Activities: None.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning
or advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
tropical events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
direct tropical threats; Events of National Significance.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 91 73 90 73 / 20 10 40 20
BTR 92 74 90 74 / 20 10 50 20
ASD 91 76 90 76 / 50 30 50 20
MSY 94 81 92 81 / 50 30 50 20
GPT 88 77 88 76 / 60 40 50 20
PQL 89 73 88 74 / 50 40 40 20
&&
.LIX Watches/Warnings/Advisories...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion...DELAYED
National Weather Service Melbourne FL
449 AM EDT SAT SEP 3 2016
.DISCUSSION...
...High Rain Chances Today...
...Moderate Rip Current Risk...
Today-Tonight...
A weak trough trailing from Hermine will extend into the northern
peninsula. A swath of high moisture will extend across central
Florida with precipitable water values at or above 2 inches
areawide. Aloft, weak ridging will be nosing back towards the
southern peninsula. This is relevant to the forecast as there
should not be as much convection in the eastern Gulf of Mexico
sending debris clouds across the area. Hence there will be a
little more daytime heating, which will allow more convection to
break out.
Prevailing southwest flow through a deep layer will push
showers/storms across the area during the afternoon and early
evening. MOS PoPs were high across the entire area, 60-80 percent
except in the far southeast. Don`t see much reason to differ
greatly from those values, but have capped them at 70 percent.
Temps aloft will continue to not be so cool and wind fields have
greatly diminished, but brief microbursts producing wind gusts
40-50 mph will be possible. With a little more heating today,
there should be an uptick in lightning with a few strong storms
producing frequent strikes. High atmospheric moisture will also
lead to local 2-3 inch rainfall amounts.
Expect most of the convection to diminish by sunset, but will
keep a small PoP a little past 00z since the environment is so
moist.
Max temps should be a degree or two higher over most of the area,
upper 80s with a few readings reaching 90 degrees especially
across the south.
Sun-Mon...Hermine will transition to offshore of the DE/NJ coasts
through the period well away from FL. The trailing band of deep
tropical moisture and weak sfc trough remains stretched from the
circulation back across the Mid-Atlantic waters and across the north
half of the peninsula. High pressure desires to re-establish aloft
with sfc ridging working hard to intrude across the western Atlantic
toward FL. The result is a general SW-S wind flow and variable at
times in vicinity of the trough. Rain chances will have a north to
south distribution once again with better chances north of Orlando.
Cloud cover and enhanced rain chances will keep oppressive heat
dialed back with Max Temps in the U80s/L90s, but conditions will
remain muggy. Min temps M/U70s.
Tue-Fri...GFS/ECMWF Models in general agreement to have Hermine hang
around offshore of the NJ coast through mid week but then ECMWF
kicks it NE while the GFS much slower to do likewise toward the end
of the week. Locally, the aforementioned moisture band will thin
(and locally dry) and the weak sfc trough will wash as high pressure
bridges and associated axis relocates. Onshore flow should
eventually win out as the week progresses. Late week may realize a
return of moisture from the southeast. So, slightly lower rain
chances by mid-week then with a reversed south to north distribution
beyond. Max temps in the U80s/L90s and Mins in the M/U70s.
&&
.AVIATION...
VFR conditions this morning except for local MVFR ceilings. Numerous
showers and scattered storms will move northeast across the
peninsula mainly during the afternoon hours. Have not included
tempo groups yet but plan to include at most sites as cloud/heating
trends become more apparent and the HRRR model settles in on a basic
overall scenario. Local strong wind gusts will still be possible,
but not nearly as widespread as yesterday.
&&
.MARINE...
Today-Tonight...The Atlantic high pressure ridge nosing back towards
the southern peninsula has already decreased the pressure gradient
substantially. Expect south/southwest winds 10 knots or less with
seas 2-3 feet. The HRRR model is suggesting a rather long line of
showers/storms moving across the coast this afternoon and well out
into the Atlantic. Therefore would expect Special Marine Warnings
along most of the coast for wind gusts around 35 knots.
Remainder of Holiday Weekend...winds and seas will be below
cautionary concerns with winds 10 knots or less. Winds generally
south to southwest but variable in vicinity of a weak sfc trough
diminishing across north FL. Seas around 2 feet nearshore and 3-4
feet offshore Sun, but with an up-tick to 3-5 feet building on Mon,
especially south of Sebastian from swell.
Early Next Week...Southeast winds overspread as high pressure moves
in. Speeds 10 knots or less with seas 3-4 feet nearshore and up to
5 feet well offshore south of Sebastian.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 88 74 87 74 / 70 30 60 30
MCO 88 74 91 75 / 70 20 60 30
MLB 89 74 90 75 / 60 30 30 30
VRB 89 73 90 75 / 60 30 30 30
LEE 87 75 88 75 / 70 20 60 30
SFB 89 75 90 74 / 70 20 60 30
ORL 88 75 90 75 / 70 20 60 30
FPR 90 73 90 75 / 60 30 20 30
&&
.MLB Watches/Warnings/Advisories...
FL...None.
AM...None.
&&
$$
SHORT TERM...Lascody
LONG TERM....Sharp
Area Forecast Discussion
National Weather Service Omaha/Valley NE
339 AM CDT SAT SEP 3 2016
.SHORT TERM...(today through Monday)
Issued at 338 AM CDT SAT SEP 3 2016
Manual 00z upper-air analysis revealed a mid-level trough over
western Canada into the Pacific Northwest with a weaker downstream
perturbation over the northern and central High Plains. Meanwhile
farther east, an amplified ridge stretched from Ontario into the
southern High Plains. In the low levels, plan-view observations
and 00z sounding data indicated a meridionally oriented moisture
axis over the central High Plains, which is likely in the process
of shifting east with the nocturnally veering LLJ. Weak air mass
destabilization associated with the moisture advection coupled
with forcing for upward vertical motion attendant to the migratory
mid-level trough should be sufficient to foster isolated showers
and thunderstorms which could move into our area later this
morning.
Recent runs of the operational and experimental HRRR
suggest that some of this convection could persist into this
afternoon across portions of east-central and southeast Nebraska.
The distribution and duration of this convection and it`s
associated cloud cover will have implications on this afternoon`s
high temperatures with values in the mid to upper 70s currently
anticipated. Deeper mixing of strong low-level flow should yield
breezy conditions, mainly over northeast Nebraska.
Tonight, deeper-layer forcing for ascent will shift east of the
area in tandem with the passage of the mid-level trough. However,
a nocturnal LLJ will once again become established over the mid
Missouri Valley with moisture and warm thermal fluxes enhancing
destabilization/lift and the potential for widely scattered
thunderstorms, which will be most probable over northeast
Nebraska. Some of this activity could linger through Sunday
morning over northeast Nebraska and west-central Iowa with residual
clouds potentially limiting daytime heating in those locations. As
such, we have lowered afternoon highs slightly. A 40-45 kt
southerly LLJ will be maintained through the day with diurnal
mixing resulting in breezy to windy conditions by afternoon.
Sunday night, a weak mid-level wave will translate northeast
through the Dakotas, focusing the greatest potential for nocturnal
convection to our north. But, given the presence of a 40-50 kt
LLJ, and the continued moistening and destabilization of the
ambient air mass, a chance of thunderstorms will exist with the
highest probability of occurrence across the northern half of the
CWA. On Monday, a significant short-wave trough will eject from
the western U.S. long-wave trough across the northern High Plains,
forcing an associated surface cold front to a location just
northwest of our area by afternoon. A pronounced low-level thermal
ridge is forecast ahead of the front, boosting high temperatures
in the upper 80s to lower 90s with gusty south winds.
.LONG TERM...(Monday night through Friday)
Issued at 338 AM CDT SAT SEP 3 2016
Consensus of 00z medium-range guidance is suggestive that the
western U.S. trough initially centered from the northern
Intermountain Region to lower Colorado Valley will progress east
and de-amplify with time, eventually moving through the northern
and central Plains Wednesday into Wednesday night. At the surface,
a cold front will settle south into at least the northern portion
of our area Monday night before oscillating north and south over
the same general area through mid week. This boundary will be the
primary focus for episodic thunderstorm activity, some of which
could be strong to severe with localized flooding also possible.
The mid-level pattern will temporarily transition to zonal over
the the north-central CONUS on Thursday before the pattern
amplifies with the approach of at least one substantial short-wave
trough into the northern Plains next week. This upper-air pattern
configuration will maintain the presence of a low-level
baroclinic zone in the region, which in turn, will support a
continued chance of thunderstorms through the remainder of the
extended period.
&&
.AVIATION...(06Z TAFS for KOFK...KLNK and KOMA.)
Issued at 1143 PM CDT FRI SEP 2 2016
VFR conditions are forecast through Saturday evening with
broken high clouds through the afternoon. Scattered to broken
cumulus clouds near FL050 are expected during the late morning and
afternoon, with south to southeast winds increasing into the 15 to
25 kt range.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Mead
LONG TERM...Mead
AVIATION...Dergan
Area Forecast Discussion
National Weather Service Pueblo CO
1127 PM MDT FRI SEP 2 2016
.SHORT TERM...(This evening through Saturday)
Issued at 224 PM MDT Fri Sep 2 2016
...Warming up tomorrow...
Pretty pronounced shortwave now moving through western CO per WV
imagery...and will move through southeastern CO over the next few
hours. Sct storms should continue to develop in a broken SW-NE line
that will shift through the I-25 corridor late this afternoon, then
clear into the E Plains after 00Z. Models indicate that some
lingering Isold convection could continue through
tonight...especially over the Upper Arkansas and Pikes Peak Region,
but the bulk of the heavier precip should be done by this evening.
Current analysis is showing 1-2000 j/kg of CAPE and 30-40 kts bulk
shear over the Plains, so despite the relatively calm start to
convection this afternoon, still see the threat of some svr storms
later this afternoon, particularly over the SE Plains. Hail to half-
dollar size and wind gusts to 60 mph will be the main svr threats
from the strongest cells than can remain reasonably isolated during
this period.
Tonight into tomorrow...convection should wind down as the short wave
moves off to our east. Could see some areas of low clouds develop or
persist overnight depending on extent of precip. SW flow will
increase on Saturday which will bring warmer wx to our area for the
weekend...with temps near 90 degrees over the Plains tomorrow. Best
forcing for storms will be north of our area, but cannot rule out
some Isold activity over the plains. Severe parameters tomorrow will
be more favorable for organized storms...so could once again see
some strong to svr storms develop, particularly over the far Ern
Plains. Rose
.LONG TERM...(Saturday night through Friday)
Issued at 224 PM MDT Fri Sep 2 2016
Sat night and Sun, an upper level trof will be over the western
U.S., with southwest flow aloft over the forecast area. It looks
like mainly isold pcpn wl be possible Sat evening, and mainly over
and near the mtns, with most if not all activity ending by late
night. Sun a weak shortwave trof wl move acrs the forecast area in
the morning and afternoon hours. This disturbance may help kick off
few showers and storms, but conditions wl generally be dry and only
isold pcpn is expected. Breezy south to southwest winds are expected
on Sun, and High temps should be around average in the San Luis
Valley, and a little above average acrs the southeast plains.
The sw flow aloft continues on Labor Day as an upr trof remains over
the wrn portions of the country. Should see some breezy south to
southwest winds again. Mon looks like a relatively dry day, but by
evening, the NAM and the ECMWF show showers/tstms acrs the southeast
corner of CO. The GFS shows chances for more widespread pcpn.
On Tue, the upr trof out west moves closer to CO and the tap of
monsoon moisture into the state returns. Thus, with the increased
moisture, there wl be a better chance for showers and tstms,
especially over and near the higher terrain. The upr trof then
moves acrs the state on Wed and Wed night with drier westerly flow
expected. High temps on Tue and Wed are expected to be around
average for the southeast plains, and a little below average in the
high valleys.
Dry westerly flow continues on Thu. Then on Fri, a new upr trof
moves into the northern Rockies and over CO, bringing more moisture
to the area and chances for pcpn and maybe a slight cooling.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1119 PM MDT Fri Sep 2 2016
Small but rather vigorous area of convection coming northeastward
over the San Juans as of 05z, and will add a vcts mention at
KALS to account for at least remnants of this area moving across
the valley through 09z. KCOS and KPUB should remain VFR through
the night, as past few runs of the HRRR show a nly component to low
level winds through sunrise, which should keep stratus at bay. On
Sat, air mass over the area will continue to dry, especially over
the mountains and I-25 corridor. Will keep any mention of VCTS
out of all tafs at this point, as most storms will be fairly high
based and should stay close to the higher terrain through the
day. Perhaps a few stronger storms may develop on the far eastern
plains near the KS border toward 00z, as weak boundary and higher
CAPE air mass interact.
&&
.PUB Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...ROSE
LONG TERM...28
AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Bismarck ND
921 AM CDT SAT SEP 3 2016
.UPDATE...
Issued at 908 AM CDT Sat Sep 3 2016
Showers with a few thunderstorms continue along and behind a
frontal boundary stretched through western North Dakota. For mid-
morning update have adjusted precipitation chances a bit to line
up with latest radar trends. Have also incorporated some HRRR
guidance which seems to have a handle on the precipitation
pushing in from Montana, but not on the activity already draped
over northwest North Dakota.
UPDATE Issued at 632 AM CDT Sat Sep 3 2016
At 6 am CDT a cold frontal boundary extended from near Minot
southwest to near Dickinson then into western South Dakota. The
front will be the focus for increasing chances for thunderstorms
today and tonight as it becomes nearly stationary across the
region.
So far the frontal boundary has been rather quiet as the stronger
shear remains to the west and the normal diurnal trends are in
place. Expect the thunderstorms to become more numerous along the
boundary especially by late this afternoon and early evening.
This forecast will mainly update current conditions as the
forecast looks to be on track.
&&
.SHORT TERM...(Today and tonight)
Issued at 254 AM CDT Sat Sep 3 2016
The highlights of the short term will be the potential for strong
thunderstorms along a slowly advancing cold front in central
North Dakota late this afternoon and tonight.
A well developed h500 west coast trough will continue to slowly
evolve, move east and bring increasing southwest winds aloft to
the region. Tonight the cold front will be aligned with the flow
aloft and the 30+ kt bulk shear will be increasing across the
region. At the same time cape values of 2000 will line up along
the frontal boundary. There is a marginal threat for severe
weather during the late afternoon and evening hours across
central and east central North Dakota. Highs today will be warmest
along the cold front in central North Dakota where high
temperatures could reach the mid 80s. Otherwise 70s to lower 80s.
Tonights lows will be in the mid 50s to lower 60s.
.LONG TERM...(Sunday through Friday)
Issued at 254 AM CDT Sat Sep 3 2016
The highlights for the extended include the threat for severe
weather on Sunday, which is an extension of the saturday night
threat, and potential moderate to heavy rainfall.
Sunday will see stronger wind shear with the best cape focused
along the slowly moving cold front now forecast near the James
river valley. With the moderate to strong wind shear aligned with
the cold front the thunderstorms are forecast to quickly form
into lines and possibly bowing line segments bringing the initial
threat large hail transitioning to damaging winds. A slight risk
for severe weather is expected sunday and sunday evening for this.
The heavy rain potential is highlighted due to high precipitable
water (near 99th climatological percentile) for this time of the
year. Also with the flow aloft nearly parallel to the frontal
boundary the thunderstorm lines will likely follow the MBE (meso-
Beta element) scale of motion which will be generally a slow
eastward progression. Fast moving cells within the line will move
northeast but the line movement will be slowly east. Moderate to
heavy rainfall is possible across the James river valley sunday
and Sunday night. Too much uncertainty now to include and flash
flood watches and dont feel the rainfall will be enough to
warrant it. however 2 to 3 inches of rainfall in 6 to 12 hours is
possible with locally higher amounts.
the remainder of the week will see several more shortwaves moving
through persistent southwest flow aloft as this h500 trough
remains across the region. So an active but cool weather pattern
will round out the week with highs mainly in the 60s.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 632 AM CDT Sat Sep 3 2016
The chances for showers and thunderstorms will be on the
increase, especially after 00z Sunday. The best chances should be
at KBIS and KJMS as a frontal boundary moves across the area.
Ceilings and visibilities should fall into at least the MVFR range.
Thought about going lower (IFR), but held off since it appears most
model solutions wait to bring that in until just after 12 Sunday.
&&
.BIS Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...JJS
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...CK
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
1040 AM CDT SAT SEP 3 2016
.DISCUSSION...Water vapor imagery shows a mid level vorticity
center over the coastal waters with a slow drift to the southwest.
Models show this vorticity maximum moving into the lower and
middle Texas coast this afternoon. Adequate moisture is in place
over the region with precipitable water values around 2 inches.
Latest HRRR along with SREF indicate scattered convection will
develop over the coastal plains this afternoon. Raised PoPs 10
percent over this region. Kept a lingering slight chance PoP in
the Victoria area into early this evening. No changes to the
current temperature forecast.
&&
.PREVIOUS DISCUSSION... /Issued 632 AM CDT SAT SEP 3 2016/
DISCUSSION...
See 12Z Aviation discussion.
AVIATION...
Main issue remains whether there will be showers at the terminals
(even possible thunder). Overall, did not change too much in the
previous thinking, going with VCSH/TEMPO SHRA at KALI AND KCRP
(TEMPO SHRA group between 15Z and 21Z...earlier at KCRP and later
at KALI), with VCTS/TEMPO TSRA at KVCT for afternoon period. At
KLRD, went with VCSH (instead of VCTS) as confidence in thunder
getting that far west is not expected now. VFR outside of
convection through 04/06Z, with winds becoming more east but
generally staying less than 11 knots for all terminals (maybe a
bit higher at KCRP), with diminishing winds (becoming light again)
after sunset. Could have some light fog at KALI and KVCT, but
confidence having that after 04/06Z is to put in KVCT and only
going 6SM at this time as model sounding not hinting at it very
much.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 95 77 94 78 94 / 30 20 40 20 40
Victoria 94 74 93 75 91 / 40 20 40 20 40
Laredo 98 77 96 78 96 / 20 10 20 10 20
Alice 96 75 95 76 95 / 30 10 40 20 30
Rockport 91 79 92 81 92 / 30 20 40 20 40
Cotulla 97 76 95 77 95 / 20 10 20 10 30
Kingsville 97 75 95 77 94 / 30 20 40 20 40
Navy Corpus 92 80 91 81 92 / 30 20 40 20 40
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
TMT/89...SHORT TERM
Area Forecast Discussion
National Weather Service Dodge City KS
542 AM CDT SAT SEP 3 2016
...Updated aviation section...
.SHORT TERM...(Today and tonight)
Issued at 408 AM CDT Sat Sep 3 2016
Water vapor satellite and RAP analysis show an elongated mid
tropospheric trough axis extending from eastern SD down into western
KS. This is in advance of a much larger scale west-southwest flow
pattern extending all the way to the Pacific Coast of California.
The persistent west-southwest flow aloft will keep the lower
tropospheric lee trough in place across easterN Colorado. As far as
precipitation goes, convergence and warm advection in the 850-700mb
layer provided enough upward vertical motion to support a narrow
axis of weak convection along roughly a Dighton to Garden City to
Liberal line (as of 0850z). This axis of shower/thunderstorm
activity will advance east through the morning hours, and we will
keep some 20 POPs in for this scattered convective activity.
Surface winds will ramp up today as the pressure gradient tightens
with deepening lee trough (sub-1000mb). Gradient will support
strongest winds generally west of Highway 283 to the Colorado border
where sustained 20 knots should be common this afternoon. Boundary
layer convergence along the lee trough axis will be in the
traditional location of Baca County, CO into far east central CO. We
will have some slight chance POPs along the CO border from late
afternoon into the early evening. We will have some Chance POPs,
around 30 percent, later in the evening from roughly Scott City to
Wakeeney to Hays where a more organized MCS may track across
northwest KS, perhaps clipping these areas.
.LONG TERM...(Sunday through Friday)
Issued at 408 AM CDT Sat Sep 3 2016
A mean longwave trough will be the story across the western CONUS
through much of this period. This will keep western Kansas in a
general southwest flow pattern aloft, keeping the leeside trough in
the lower levels a prevailing feature through the holiday weekend
into much of next week. Downslope of the higher terrain of New
Mexico will lead to increased capping in the 850-700mb layer, which
will make it more difficult to get thunderstorm activity much of
this period. Nevertheless, a few isolated to widely scattered
thunderstorms will be possible late afternoon and evening in
traditional lee trough convergence zones in far west central/far
southwest KS Sunday, Monday, and even into Tuesday. By Wednesday,
there are indications from the ECMWF and GFS that a fairly
formidable wave/jet streak will finally come out into the High
Plains, which would advance the lee trough across western Kansas,
pushing the precipitation chances farther east. Still though, the
best upper jet and baroclinic zone supporting larger scale upward
vertical motion will be up into Nebraska, so it is hard to really
find much to get too excited about regarding widespread thunderstorm
activity with a lot of precipitation. We will not likely have a
decent front push through our region again until at the very end of
this forecast period (Sep 9-10).
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 541 AM CDT Sat Sep 3 2016
MVFR conditions will continue this morning due to low level
clouds. VFR conditions are then expected from late morning into
the afternoon hours. Lee troughing will continue across eastern
Colorado leading to southerly winds felt at the TAF sites. Breezy
conditions are expected from late morning through the early
evening as the atmosphere mixes and the pressure gradient
tightens.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 84 66 89 70 / 30 10 10 10
GCK 86 66 92 69 / 20 20 20 10
EHA 89 65 91 67 / 20 30 20 10
LBL 87 66 91 70 / 20 10 20 10
HYS 84 66 89 71 / 30 40 10 10
P28 85 68 88 71 / 20 10 10 10
&&
.DDC Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Hovorka_42
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1029 AM CDT SAT SEP 3 2016
.UPDATE...
Isolated weak convection continues in a convergence zone over the
Winter Garden area near Uvalde. Visible imagery shows ACCAS or
other pre-convective cumulus around South Central Texas. The
latest TTech WRF and HRRR runs have widespread, weak convection
this afternoon. In contrast, the NCAR ensemble members have
significant convection with some isolated heavy rain pockets,
especially over the Hill Country. We believe the most likely
evolution will be in-between, scattered weak convection, but the
strongest storms over the Hill Country. All of the grid, text, and
graphic forecasts were just updated to re-trend variables and re-
focus PoPs.
&&
.PREV DISCUSSION... /ISSUED 400 AM CDT SAT SEP 3 2016/
SHORT TERM (Today through Sunday)...
Similar pattern to yesterday expected today. Again expecting
isolated to scattered convection beginning around 18Z and
persisting through 00Z. PWATs and instability suggest another
possibility for localized heavy rainfall and generally slow moving
cells. Storms yesterday were able to produce healthy outflow
boundaries triggering multiple interactions and additional cell
development by late afternoon. Would expect more of the same again
this afternoon...increasing coverage by peak heating hours.
Should again see this activity wane quickly after dark with only
a couple cells remaining after 00Z. Lows have been able to fall a
few degrees below guidance tonight due to lack of cloud cover
overnight. Trended similarly for tomorrow night as well.
The focus for Sunday (and through Wednesday) will then turn to the
Coastal Plains and areas generally along and east of the I-35 corridor
for PoPs. This is largely due to the strengthening ridge over the
MS river valley. It does appear that good deep layer moisture will
advect onshore Sunday afternoon and spread westward. Superblend
suggested areas south of I-10 and east of I-35 were the preferred
areas for PoPs and diminishing westward. Think this is fair as
models are suggesting a pretty strong PWAT gradient from west to
east.
LONG TERM (Sunday Night through Friday)...
Similar pattern expected Monday through Wednesday...with generally
lowering PoP chances each day. As the upper ridge continues to
strengthen through the week, the ability for good deep layer
moisture from the gulf to advect westward diminishes...and by late
in the week, the ridge axis spans from Del Rio up through the
Tennessee Valley.
GFS/ECMWF/Canadian all agree on a tropical system coming on shore
to Baja California by Wednesday and bringing significant Pacific
moisture across Far West Texas and New Mexico but due to the
orientation of the upper high at that point, we will likely miss
out on that moisture tap. Thus, a dry forecast and likely hotter
forecast looks in store for the late week and into the weekend.
Trended a couple degrees above Superblend for late in the week.
MEX and ECE were both suggesting at least a couple degrees above
Superblend and agree with the lack of moisture and ridge axis
overtop.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 91 74 91 76 91 / 30 10 20 10 30
Austin Bergstrom Intl Airport 91 73 91 75 91 / 30 10 30 10 30
New Braunfels Muni Airport 92 73 91 75 91 / 30 10 30 10 30
Burnet Muni Airport 89 73 89 74 89 / 20 10 20 10 30
Del Rio Intl Airport 93 74 92 76 91 / 30 10 10 10 20
Georgetown Muni Airport 90 74 91 76 90 / 20 10 20 10 30
Hondo Muni Airport 92 74 91 75 92 / 30 10 20 10 30
San Marcos Muni Airport 91 72 90 74 90 / 30 10 30 10 30
La Grange - Fayette Regional 92 75 91 77 92 / 30 10 30 10 40
San Antonio Intl Airport 92 75 91 77 91 / 30 10 30 10 30
Stinson Muni Airport 93 76 92 77 93 / 30 10 30 10 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...26
Synoptic/Grids...Allen
Public Service/Data Collection...33
Area Forecast Discussion
National Weather Service Goodland KS
542 AM MDT SAT SEP 3 2016
.SHORT TERM...(Today through Monday night)
Issued at 418 AM MDT Sat Sep 3 2016
Morning WV imagery and RAP upper level analysis shows a shortwave
trough currently moving east of our CWA. A strong upper level jet
is digging into western Colorado. Surface low pressure is in place
across eastern Colorado with south-southwest gradient across our
CWA.
Today-Tonight: They day starts off with subsidence in wake of the
departing shortwave trough. As the upper level jet moves eastward
large scale forcing should recover and the combination of a very
deep moist air mass, moderate instability, and weak surface
convergence should lead to thunderstorm development with increasing
coverage in the late afternoon and evening. There should be very
good deep layer shear (Bulk effective shear around 45kt) and 0-3km
helicity around 200 m2/s2 favorable of supercell development and an
elevated risk for severe weather across our CWA. Trend in high
resolution guidance is for activity to merge into several clusters or
MCS and transition eastward through the evening. I trended PoPs
upwards, and if precip signal continues in short range guidance I
could see bumping PoPs up further (once there is a better handle on
covergence zones). As mean flow shifts to the SW WAA should increase
and model consensus is for slightly warmer temperatures. Main period
of warming will get underway tonight and afterwards.
Sunday-Monday night: SW aloft persists with warming temperatures and
shift in main storm track slightly to the north. There should be
enough instability/weak forcing to support isolated (or scattered)
thunderstorm development over parts of our CWA, though trend right
now favors locations north of our CWA. Temperatures will also
recover in this pattern, with above normal highs in the 90s
across our CWA and lows near 70 in our east.
.LONG TERM...(Tuesday through Friday)
Issued at 309 AM MDT Sat Sep 3 2016
The long term period has two opportunities for precipitation over
the CWA. The first is Tuesday, where a continuing southwest flow
into the region is present due to a trough in the western CONUS and
ridge in the eastern CONUS. Guidance is showing a cold front moving
into the northern periphery of the CWA Tuesday and continuing south
through the day. This will help with storm development in the
northern counties of the CWA. Come late Wednesday, the front and
trough will have moved east of the region bringing zonal flow over
the CWA. This will bring dry conditions to the area through
Thursday. The second opportunity for precipitation will be Friday.
This is due to another trough moving into the region and bringing a
cold front with it. Current model runs and guidance have the front
moving over the eastern CWA counties, which will likely be the
location for storm development. Will keep an eye on timing and
location of the frontal boundaries as the week progresses.
Temperatures are expected to be in the mid to upper 80s through the
period. Friday could potentially see temperatures in the 70s over
some locations if the cold front moves in quicker.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 541 AM MDT Sat Sep 3 2016
IFR CIGS will be possible this morning and again late tonight at
both KGLD and KMCK. Better chances this morning will be at KGLD
and at KMCK around sunrise Sunday morning. Thunderstorms should
develop over parts of the region by midday with better coverage in
the late afternoon and evening period. Severe thunderstorms (large
hail/strong winds/heavy rain) will be possible, but confidence is
too low to prevail more than VCTS at this time. Better coverage
may remain south of KMCK based on most model trends. Gusty winds
should continue through the day due to tight surface gradient in
place over the region. 12-17kt winds should generally prevail out
of the south through the TAF period. A few gusts 25-30kt will be
possible during the afternoon.
&&
.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...CLT
AVIATION...DR
Area Forecast Discussion
National Weather Service New Orleans LA
817 AM CDT SAT SEP 3 2016
...SOUNDING DISCUSSION...
With a little cooling and drier air on the Northshore there is
a greater radiation inversion at the sfc than has been observed
in a while. It will mix out quickly with morning heating. Overall
the airmass is drier with PW closer to average at 1.9 inches.
Enough instability is present for storms later today with mixed
layer CAPE at 1400 J/KG. Slightly more instability is present across
areas to the south and east of Slidell where the more moist
airmass remains. Winds though are very light through the profile
going from southerly just above the sfc to westerly by 800 mb.
Krautmann
&&
.PREV DISCUSSION... /issued 342 AM CDT SAT SEP 3 2016/
SHORT TERM...
Drier air has filtered in to northern portions of the forecast
area as a weak frontal boundary sagged south towards the Gulf of
Mexico. Currently the front appears to be located from south of
Lafayette to Lake Pontchartrain to north of Mobile. There is about
a 7 to 10 degree difference in dewpoints between north and south
of the boundary. Thinking that this will be a large contributing
factor to where convection initiates this afternoon. Thus believe
that the GFS and ECMWF indicate thunderstorms developing too far
north in the CWA while the HRRR shows storms more correlated to
where the higher surface moisture is. So have adjusted today`s
pops accordingly with near 60% from a HUM to MSY to GPT line and
barely 20% from BTR to MCB to capture the more isolated convection
expected there. Glancing at model soundings, an inverted-V becomes
apparent during the afternoon hours along with dry air aloft
which would suggest the potential for microbursts. A few storms
could produce damaging winds in the strong to maybe severe range.
Otherwise, highs should be running in the low to mid 90s with New
Orleans and Hammond being the hotspots.
LONG TERM...
The upper trough to the east will be quickly lifting northeast
while while a maritime upper level ridge builds over the gulf
south over the next few days. This will promote moisture return to
the whole forecast area and subsequently higher chance for
rainfall. Expect a typical diurnal pattern with convection
initiating late morning and thunderstorms carrying over into the
afternoon and early evening hours. Greatest coverage at this time
appears to be Sunday and Labor day at around 30 to 50%. The ridge
will begin to translate into a more continental ridge and then
start to shield the CWA from convection as the center moves close
to the northern coast of the Gulf of Mexico.
MEFFER
AVIATION... VFR conditions should remain through the morning hours
at all terminals. Better chances for sh/ts will exist along and
south of a line from Donaldsonville, LA to Poplarville, MS. Tempo
groups will be used for these areas. To the north of that line,
thunderstorms will still be possible but not as numerous. TAF
updates for these areas should suffice. Microburst potential will be
higher today but since this is a conditional field, it will mean
that a thunderstorm will have to develop nearby or over the field to
receive strong or damaging wind speeds.
MARINE...
Light winds and low seas expected for the remainder of this forecast
package. Nocturnal sh/ts will continue as well through the week.
DECISION SUPPORT...
DSS code: Green.
Deployed: None.
Activation: None.
Activities: None.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning
or advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
tropical events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
direct tropical threats; Events of National Significance.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 91 73 90 73 / 20 10 40 20
BTR 92 74 90 74 / 20 10 50 20
ASD 91 76 90 76 / 50 30 50 20
MSY 94 81 92 81 / 50 30 50 20
GPT 88 77 88 76 / 60 40 50 20
PQL 89 73 88 74 / 50 40 40 20
&&
.LIX Watches/Warnings/Advisories...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Omaha/Valley NE
628 AM CDT SAT SEP 3 2016
.SHORT TERM...(today through Monday)
Issued at 338 AM CDT SAT SEP 3 2016
Manual 00z upper-air analysis revealed a mid-level trough over
western Canada into the Pacific Northwest with a weaker downstream
perturbation over the northern and central High Plains. Meanwhile
farther east, an amplified ridge stretched from Ontario into the
southern High Plains. In the low levels, plan-view observations
and 00z sounding data indicated a meridionally oriented moisture
axis over the central High Plains, which is likely in the process
of shifting east with the nocturnally veering LLJ. Weak air mass
destabilization associated with the moisture advection coupled
with forcing for upward vertical motion attendant to the migratory
mid-level trough should be sufficient to foster isolated showers
and thunderstorms which could move into our area later this
morning.
Recent runs of the operational and experimental HRRR
suggest that some of this convection could persist into this
afternoon across portions of east-central and southeast Nebraska.
The distribution and duration of this convection and it`s
associated cloud cover will have implications on this afternoon`s
high temperatures with values in the mid to upper 70s currently
anticipated. Deeper mixing of strong low-level flow should yield
breezy conditions, mainly over northeast Nebraska.
Tonight, deeper-layer forcing for ascent will shift east of the
area in tandem with the passage of the mid-level trough. However,
a nocturnal LLJ will once again become established over the mid
Missouri Valley with moisture and warm thermal fluxes enhancing
destabilization/lift and the potential for widely scattered
thunderstorms, which will be most probable over northeast
Nebraska. Some of this activity could linger through Sunday
morning over northeast Nebraska and west-central Iowa with residual
clouds potentially limiting daytime heating in those locations. As
such, we have lowered afternoon highs slightly. A 40-45 kt
southerly LLJ will be maintained through the day with diurnal
mixing resulting in breezy to windy conditions by afternoon.
Sunday night, a weak mid-level wave will translate northeast
through the Dakotas, focusing the greatest potential for nocturnal
convection to our north. But, given the presence of a 40-50 kt
LLJ, and the continued moistening and destabilization of the
ambient air mass, a chance of thunderstorms will exist with the
highest probability of occurrence across the northern half of the
CWA. On Monday, a significant short-wave trough will eject from
the western U.S. long-wave trough across the northern High Plains,
forcing an associated surface cold front to a location just
northwest of our area by afternoon. A pronounced low-level thermal
ridge is forecast ahead of the front, boosting high temperatures
in the upper 80s to lower 90s with gusty south winds.
.LONG TERM...(Monday night through Friday)
Issued at 338 AM CDT SAT SEP 3 2016
Consensus of 00z medium-range guidance is suggestive that the
western U.S. trough initially centered from the northern
Intermountain Region to lower Colorado Valley will progress east
and de-amplify with time, eventually moving through the northern
and central Plains Wednesday into Wednesday night. At the surface,
a cold front will settle south into at least the northern portion
of our area Monday night before oscillating north and south over
the same general area through mid week. This boundary will be the
primary focus for episodic thunderstorm activity, some of which
could be strong to severe with localized flooding also possible.
The mid-level pattern will temporarily transition to zonal over
the the north-central CONUS on Thursday before the pattern
amplifies with the approach of at least one substantial short-wave
trough into the northern Plains next week. This upper-air pattern
configuration will maintain the presence of a low-level
baroclinic zone in the region, which in turn, will support a
continued chance of thunderstorms through the remainder of the
extended period.
&&
.AVIATION...(12Z TAFS for KOFK...KLNK and KOMA.)
Issued at 623 AM CDT SAT SEP 3 2016
VFR conditions should dominate the TAF cycle. A few showers are
passing near KOFK but not close enough to include in the TAF.
Given isolated nature, will hold off on mention unless something
develops. Better chance of showers in the area will be tonight,
and have included a PROB30 group for showers with a slightly
lowered visibility. Could see some thunder, but at this range,
will keep it at a shower mention. Kept precip mention out of KOMA
and KLNK as chances are lower. Confidence is lower in evolution of
showers or isolated storms today and tonight near those sites, and
will wait for better agreement or for development to show itself
before mentioning. At all sites, southeast winds should increase
with gusts from late morning to sunset, then decrease diurnally
this evening and tonight.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Mead
LONG TERM...Mead
AVIATION...Mayes
Area Forecast Discussion
National Weather Service Tucson AZ
345 AM MST SAT SEP 3 2016
.SYNOPSIS...Dry conditions through Monday except for a few
thunderstorms this afternoon mainly across the White Mountains.
Expect slightly above average daytime temperatures this holiday
weekend. Increasing moisture from the south will then provide a
chance of showers and thunderstorms during the middle and latter
part of the upcoming week.
&&
.DISCUSSION...Upper level trough axis adjacent the West Coast with
an upper ridge axis extending from Texas northeastward into the Great
Lakes region early this morning. This pattern has resulted in a very
dry regime above 500 mb across southeast Arizona as per the 03/00Z
KTWC sounding and water vapor imagery. Meanwhile, dewpoints at lower
elevations valid 3 AM MST ranged from the upper 50s across eastern
sections to the mid 40s from Tucson westward into western Pima Co.
03/00Z Univ of AZ WRF NAM/GFS and several HRRR solutions were
similar with depicting the potential for a few showers/tstms to
occur this afternoon mainly across the White Mountains. There
appears to be enough moisture to justify a slight chance of showers/
tstms this afternoon and early this evening across the Galiuro and
Pinaleno Mountains including Mount Graham, and across the Chiricahua
Mountains in eastern Cochise County. Any showers/tstms should end
around sunset this evening followed by precip-free conditions area-
wide late tonight through Monday evening.
Thereafter, increasing moisture is progged via the 03/00Z GFS/CMC/
ECMWF to be drawn northward across the area starting as early as
late Monday night, though more likely Tuesday into Wednesday, ahead
of a tropical system approaching southern Baja California. There
continued to be fairly pronounced differences between the
deterministic GFS/ECMWF solutions regarding the path of the deepest
moisture ahead of this system.
The ECMWF remained similar versus previous ECMWF solutions with
keeping the mid-level circulation intact and progressively northward
across the Baja Peninsula and eventually into the northern Gulf of
California by Wednesday night. Thus, the higher liquid amounts as
per the ECMWF were west of this forecast area across southwest
Arizona and eventually into south central Arizona by next Thursday.
However, the GFS remained fairly similar versus previous GFS
solutions with shunting the deeper moisture east of this forecast
area and into the southern Rockies. Have noted that the 03/00Z GFS
did trend higher with liquid amounts across southeast Arizona Wed-
Thur versus 24 hours ago.
The upshot: a slight chance of showers/tstms across much of
southeast Arizona by Tue afternoon followed by chance-category PoPs
across much of this forecast area Wed-Thur. Would not be surprised
to see PoPs increased, and perhaps fairly substantially, with
subsequent forecast issuances. Moisture is progged to linger Friday
for at least a slight chance of showers/tstms area-wide.
High temps thru Labor Day will average just a few degs above
seasonal normals, then cooler temps will likely prevail by next
Wednesday in response to increased moisture across the area.
&&
.AVIATION...VALID THRU 04/12Z.
Isolated -TSRA/-SHRA mainly across the White Mountains NE of KSAD
this afternoon. Otherwise, clear skies west of KTUS and a FEW to SCT
clouds around 10k-15k ft msl into Sunday morning. Surface wind this
afternoon sly/swly 12-16 kts with gusts to near 25 kts. Surface wind
variable in direction less than 10 kts at other times. Aviation
discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Dry conditions through Monday except for a few
thunderstorms this afternoon mainly across the White Mountains.
Scattered thunderstorms should return to the area by Wednesday and
continue into next Friday as moisture increases from the south.
Expect occasionally gusty south to southwest afternoon winds through
Monday. 20-foot winds will generally be less than 15 mph except near
thunderstorms during the middle and latter part of next week.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
DISCUSSION...Francis
AVIATION/FIRE WEATHER...GL
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Area Forecast Discussion...corrected
National Weather Service Cheyenne WY
322 PM MDT SAT SEP 3 2016
.SHORT TERM...(This evening through Monday)
Issued at 315 PM MDT Sat Sep 3 2016
Current KCYS radar loop this afternoon shows two areas of locally
heavy rainfall associated with thunderstorms...one is associated
with the main upper level jet moving into Wyoming with training
thunderstorms developing near and south of the Colorado border and
moving northeast over central Wyoming...mainly west of I25. The
other area is associated with a shortwave disturbance over far
southeast Wyoming and the southern Nebraska panhandle. This
shortwave has seemed to stall this afternoon although models have
it progressing eastward by this evening. There has been some
impressive rainfall amounts based on radar estimates with this
activity...up to 4 inches of rain has fallen across Kimball and
far eastern Laramie county so far. This rainfall will slowly move
eastward into this evening...but additional rainfall is possible
as thunderstorms are developing further west. Some hail and gusty
winds are expected with these stronger thunderstorms.
Expect convection to linger through midnight tonight...especially
north of I80 as the upper level jet nudges east and strengthens
through tonight. Models indicate a large area of upper level
diffluence stretching from Rawlins to Chadron Nebraska. This
appears to be the most favorable area for lines of showers and
thunderstorms as convection will become more elevated in nature
through the night. In addition...current models show a quasi-
stationary front drifting southward into Converse and Niobrara
counties...which will likely enhance llvl lift. The southern
branch of the jet will become more active as well...so kept 25 to
40 percent POP along I80.
Models show the stationary front lifting back northward on
Sunday...before it moves south across the forecast area Sunday
night. High res models still hinting towards mid to late morning
thunderstorms developing over southeast Wyoming along a dryline-
like boundary moving eastward. Thunderstorms will likely occur
mid morning to early afternoon across southeast Wyoming...and
mainly in the afternoon across western Nebraska. Increased POP
further east across western Nebraska in the afternoon and lowered
POP further west for the afternoon. Some of these thunderstorms
may become strong during the afternoon across western Nebraska with
hail and gusty winds. Behind the dryline...humidities will rapidly
lower with southwest winds gusting around 40 mph at times west of
I-25. A cooler airmass will spread from north to south Sunday
night and into Monday...with early morning lows in the 40`s over
most of southeast Wyoming. Upper level trough axis will lift
northeast for Monday...as much drier air moves into the forecast
area. Any showers and tstorms will be well north of I80 and mainly
across northern Wyoming with a few cells possible across Converse
and Niobrara counties in the afternoon.
.LONG TERM...(Monday night through Saturday)
Issued at 222 PM MDT Sat Sep 3 2016
The quasi-stationary frontal boundary sags a bit farther south
as the upper trough moves through by late Monday but remains close
enough that we should see post-frontal moisture hang in across far
SE Wyoming and the Nebraska Panhandle Tuesday. We keep some late
afternoon showers and isolated storms going across our eastern
zones late Tuesday afternoon into Tuesday evening. Then as the
upper trough moves farther east, we see deeper layer dry air move
in from the southwest which should keep us rain-free through late
in the week.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1159 AM MDT Sat Sep 3 2016
Scattered showers and isolated thunderstorms developing from the
Rawlins area east across the Laramie and Cheyenne aviation areas.
We expect to see showers and thunderstorms in the vicinity of
those airports through the afternoon into the early evening before
diminishing...with scattered showers and thunderstorms developing
along I-25 moving east into the western Nebraska Panhandle through
the late afternoon and evening hours. Most storms should diminish
in the Panhandle by midnight. NAM is forecasting low ceilings and
fog Alliance to Sidney after midnight. Depending on how much rain
and surface saturation they get over there this evening, that
could happen. GFS and HRRR models not hitting the fog and low
stratus at all over there, so for now trended Alliance and Sidney
down to MVFR towards daybreak.
&&
.FIRE WEATHER...
Issued at 222 PM MDT Sat Sep 3 2016
FIRE WEATHER CONCERNS WILL REMAIN MINIMAL THROUGH THE WEEKEND AS
DAYTIME HUMIDITIES ARE EXPECTED TO BE AROUND 25 PERCENT OR HIGHER.
BREEZY SOUTHWEST WINDS WILL PREVAIL ALONG AND WEST OF I-25, WITH
GUSTS OF 35 TO 45 MPH POSSIBLE FOR LOWER ELEVATIONS OF CARBON
COUNTY SUNDAY AFTERNOON. CHANCES FOR SHOWERS AND THUNDERSTORMS ARE
EXPECTED THROUGH THE WEEKEND AS WELL, WITH WETTING RAINS A GOOD
POSSIBILITY. MONDAY LOOKS TO BE DRIER WITH GUSTY WINDS, SO WE MAY
SEE A RETURN OF FIRE WEATHER CONCERNS AT THAT TIME.
&&
.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&
$$
SHORT TERM...TJT
LONG TERM...JG
AVIATION...JG
FIRE WEATHER...JG
Area Forecast Discussion
National Weather Service Memphis TN
258 PM CDT SAT SEP 3 2016
.DISCUSSION...Surface analysis this afternoon places Post-Tropical
Cyclone Hermine while a 1025 mb ridge of high pressure is centered
over the Great Lakes Region. This ridge of high pressure is
producing sunny/mostly sunny skies across the Mid-South and
temperatures as of 2 pm CDT in the 80s across most locations.
The ridge of high pressure is expected to bring rain free weather
to the Mid-South tonight through Sunday night. Lows tonight will
be in the 60s to around 70 degrees and a few degrees warmer on
Sunday night. Highs on Sunday will be in the upper 80s to lower
90s.
The ridge of high pressure is expected to move slightly east by
next week resulting in a gradual return of southerly winds along
with slightly warmer temperatures and accompanying low level
moisture. Isolated showers and thunderstorms will be possible
mainly during the afternoon and perhaps early evening hours each
day during peak heating, with the best coverage mainly along and
west of the Mississippi River.
Long term models indicate mid-level height falls towards next
weekend as a mid level upper level trough and associated cold
front move through the Lower Mississippi Valley next Saturday.
This will bring slightly better shower and thunderstorm chances to
the forecast area, especially along and north of I-40.
CJC
&&
.AVIATION...18Z TAFs
VFR and light winds to prevail through the next 24 hours. Will
need to watch for low level moisture return at TUP during the late
overnight. This is depicted by the NAM but not the RAP or GFS
LAMP guidance.
PWB
18Z TAFs
VFR and light winds to prevail through the next 24 hours. Will
need to watch for low level moisture return at TUP during the late
overnight. This is depicted by the NAM but not the RAP or GFS
LAMP guidance.
PWB
&&
.MEG Watches/Warnings/Advisories...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Omaha/Valley NE
314 PM CDT SAT SEP 3 2016
.SHORT TERM...(tonight through Tuesday)
Issued at 315 PM CDT SAT SEP 3 2016
The main forecast concerns are in regards to thunderstorm chances
for the next few days.
Main features from the 12z upper air charts include the following.
At 300 mb...a jet streak of around 90 knots at 300 mb was noted
from western Montana into Saskatchewan. This was in the somewhat
confluent mid level flow ahead the trough that extended from
Alberta down to off the central California coast. 12 hour 500 mb
height falls were generally 20 to 60 meters east of the trough.
Monsoonal 700 mb moisture was highest from Mexico northward into
southern and western Colorado...with dewpoints of 5 to 8 degrees
Celsius. Thermal ridge at 700 mb stretched from New Mexico up into
Manitoba and western Ontario. Moist axis at 850 mb stretched from
Texas and New Mexico northward into the Dakotas. The 12Z KOAX
sounding only showed about 0.72 PW but had modest lapse rates
above 700 mb. Showers and thunderstorms to the west today have
produced some local rain amounts near an inch.
Some of the hi-res short range models tend to break up the
activity currently between Omaha and Hastings. Although the RAP13
model may be a bit overdone with amounts and coverage...it
appeared at least reasonable with its forecast this evening. Will
keep rain amounts mostly under 0.25 inches but heavier amounts are
possible. KLNK soundings from the RAP model show elevated CAPE of
around 400 J/kg with parcels originating around 750 mb. Eventually
that will spread toward KOMA. PW values are expected to increase
into the 1.5 to 2.0 inch range tonight...as a low level jet of
40-45 knots develops. RAP and some recent runs of the ESRL HRRR
show precipitation lasting into at least Sunday morning before
mostly lifting off to the northeast. Will stay fairly close to the
previous forecast highs of 80 to 85...with the warmest values in
our western counties.
The main area of convection by late Sunday afternoon should be
over the Dakotas...along and behind a cold front. Storms may
develop southward into the moist axis as a low level jet of 50-55
knots develops in the evening. Chances before midnight will be
highest in our northern counties...but will probably develop
farther south after midnight. Some severe storms appear possible
mainly in northeast Nebraska.
At this time...we have Monday as mainly dry. Decent pressure
gradient and mixing should bring breezy/windy conditions and highs
near 90 or in the lower 90s. Convection will be possible Monday
night but best forcing will likely stay to our west and north.
Storm chances should be highest in northeast Nebraska in the
evening. Shear and instability parameters support the slight risk
shown in the SPC Day 3 outlook.
By 12Z Tuesday...the 500 mb trough axis should extend from Alberta
to southern California...with our area remaining in modest
southwest mid level flow. We will also likely still be in the high
PW plume extending up from Mexico. Model agreement is only fair on
how things will play out for Tuesday. The 12Z ECMWF is more
generous with precipitation during the day for our area compared
to the GFS. Kept highest chances now in our northern zones.
.LONG TERM...(Tuesday night through Saturday)
Issued at 315 CDT SAT SEP 3 2016
Pattern for Tuesday night suggest heavy rain potential along with
a risk of severe storms with a slow moving front in our northern
areas. That is forecast to push south Wednesday and Wednesday
night. Kept rain chances highest near the front and expect some
drier air to move into northeast Nebraska by 12Z Thursday. By
that time...the 500 mb flow should be more zonal. Thursday rain
chances seem pretty low but will increase Thursday night as
southerly lower tropospheric flow increases. Models are in fairly
good agreement that a modest shortwave trough will approach from
the northwest Friday. There are some timing differences but it
should turn drier and cooler by Saturday.
&&
.AVIATION...(18Z TAFS for KOFK...KLNK and KOMA.)
Issued at 1228 PM CDT SAT SEP 3 2016
A few light showers may impact KLNK this afternoon but otherwise
VFR conditions are expected through much of the period. Did add a
PROB30 group for a few showers during the overnight and early
morning hours at both KOMA and KLNK. Increasing southwesterly low
level jet could provide a few hours of wind shear but have left
out at this point as it seem marginal. Otherwise...near term
forecast model guidance is hinting at an MVFR deck overnight in
KOFK so did put a group in for this as well.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Kern
Area Forecast Discussion
National Weather Service Pueblo CO
237 PM MDT SAT SEP 3 2016
.SHORT TERM...(This evening through Sunday)
Issued at 220 PM MDT Sat Sep 3 2016
This early afternoon some isold showers and thunderstorms had
developed from around the I-25 corridor and Palmer Dvd and westward.
A weak disturbance wl continue moving through east central and
northeast CO this afternoon and evening. Although there wl be the
possibility of isold storms ovr much of the area this evening, the
best chances wl be ovr northern portions of the forecast area, from
the central CO mtns, acrs Teller and El Paso counties and eastward.
Radar at 140 pm was showing a line of convection from north of Limon
to northeast El Paso county. The HRRR continues to show a line of
convection ovr northeast and east central CO this afternoon and
early this evening, then moving into northwest KS. This line of
convection may brush Kiowa county and could bring some heavy rain.
The latest meso analysis is showing 2000+ J/kg of CAPE ovr east
central CO and ovr the far sern corner of CO. The NAM forecast for
late this afternoon/early this evening has 0-6 km bulk shear values
of 40-50 kts ovr Kiowa county. If the convection does moves thru the
far eastern portions of the sern plains, there will be the
possibility of some severe weather, with large hail and damaging
winds being the main threats.
By late evening chances for thunderstorms will mostly end, however
locations near the KS border may see some lingering convection until
around midnight, and there could be some isolated showers or tstms
thru the night and into Sun morning along the Continental Divide.
Drier conditions are then expected on Sun, with little chance for
pcpn, but there could be a few shower/storms ovr the hyr trrn. With
an upper level trof being ovr the western U.S., the flow aloft ovr
the area will be southwesterly. At the surface, breezy south to
southwest winds can be expected, especially in the afternoon and
early evening hours. High temps on Sun are expected to be a little
above average acrs the southeast plains, and around average in the
high valleys.
.LONG TERM...(Sunday night through Saturday)
Issued at 220 PM MDT Sat Sep 3 2016
...Dry and warm week ahead...
A trough will slowly progress eastward this coming week, moving
from the great basin early on Monday to the Rockies by mid-week,
then on to the Mississippi Valley late in the week. This will
bring and extended period of dry and very warm weather.
Temperatures during this time will run from 5 to 10 degrees above
average over the Plains. Will see highs in the lower 90s for the
first half of the week as southwesterly flow persists over our
area. On Monday and Tuesday, some moisture will be drawn up from
the south as southerly flow increases over our area. This will
bring a slight chance of convection, mainly over southern portions
of our CWA. A couple of storms out over the Plains could be on the
strong to severe side given the increased winds aloft and
corresponding increase in bulk shears. Tuesday afternoon-eve looks
like the best bet for any svr at this time.
By the latter part of the week, the upper low will eject
northeastward into E Canada and SW flow will transition to
Westerly and finally Northwesterly by next week`s end, and this
will tend to bring continued breezy, warm, and dry conditions to
our area. It probably wont be until late next weekend or early the
following week that we see a return of any significant moisture.
Rose
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 220 PM MDT Sat Sep 3 2016
VFR conditions are expected at the terminal forecast sites thru the
next 24 hrs. There will be a slight chance for showers and tstms in
the vcnty of the forecast sites this evening. Breezy south to
southwest winds with gusts of 20-30 kts are forecast for Sun
afternoon.
&&
.PUB Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...ROSE
AVIATION...28