Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/28/17
Area Forecast Discussion
National Weather Service Wilmington OH
1018 PM EDT Sun Aug 27 2017
.SYNOPSIS...
A surface trough will rotate northwest into the region tonight.
An upper level low and its associated embedded disturbances will
bring unsettled weather to the region for Monday and Tuesday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Upper level low over the upper MS Valley will drop towards the
Ohio Valley tonight. A shortwave rotating around the low is
forecast to rotate around the base of the low late tonight.
Showers are expected to develop ahead of this feature. However
the trend of the models is to slow the eastward progression of
the pcpn, so delayed the onset of the pcpn by a couple of hours,
which keeps the majority of the fa dry tonight.
Pooling dewpoints along an inverted trof, well help keep
temperatures up. Expect lows tonight in the upper 50s to the
lower 60s.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
The embedded s/wv will move northeast across the forecast area
Monday morning into Monday mid afternoon. This feature will
combine with weak low level forcing from the inverted trof to
bring scattered to likely showers. Highest probability for
measurable pcpn will be across our northwest zones, with the
southeast having the lowest threat. There will be a chance of
thunderstorms, mainly during the afternoon, as diurnal
instability occurs. Temperatures will reflect where cloud cover
is the thickest and rain chances the highest. Highs will range
from the mid 70s northwest to the lower 80s south/southeast.
For Monday night, the center of the upper level closed low will
begin rotating east/southeast toward northeast Illinois/northwest
Indiana. We may see a lull in precipitation Monday evening into
early Tuesday morning as the first s/wv moves away from our
region followed by another embedded s/wv rotating around the
base of the upper level low. Have increased PoPs late for the
next feature. Instability will wane overnight which should at
least diminish the thunderstorm threat. Overnight lows will be
pretty uniform in the lower 60s given cloud cover.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Period beings with a closed H5 low centered nr Chicago. The
models work this system eastward on Tuesday, while filling it.
There should be enough lift to continue with likely PoPs for
Tuesday. The atmosphere becomes marginally unstable by late
Tuesday morning, so continued with the mention of a chance of
thunder.
As the low transitions to an open wave Tuesday night, the lift
weakens and expect the pcpn to taper off during Tuesday night. Have
increased the PoPs on Wednesday however as diurnally driven
instability produces some pop up convection.
Active pattern continues on Thursday as a cold front drops down
through the Great Lakes. The GFS is stronger and quicker with
precipitation than the ECMWF. Went with a compromise and kept pops
in the low chance category.
Models solutions differ from here forward. The GFS has a strong high
pressure over the Lakes which provides dry weather for Friday and
Saturday. The 00Z ECMWF supported this, but now the 12Z ECMWF is
weakening the high and is bringing the remnants of Harvey northward,
reaching the fa Friday night. The GEFS and ECMWF means are slower
than operation ECMWF, so leaned towards the 12Z GFS/00Z ECMWF
solution and waited until Sunday to bring pcpn chances back into the
region. Will have to keep an eye on the trends of the models, as
this might need to be adjusted.
Temperatures will remain slightly below normal through the
period.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
A closed H5 low will drop from nrn WI down towards the region
tonight. Around the low, a vort max will rotate up the Ohio
Valley. In response to the forcing, an area of showers will move
from IL to ern IN by 12Z. Previous runs of the RAP and the GFS
have been trying to develop some SHRA in the Scioto Valley along
an inverted sfc trof between 09-12Z. This seems to be an out
lying solution as the latest runs are backing off of this and
focusing on the pcpn coming in from IN.
The pcpn from the west will push into the tafs after 12Z, with
the best coverage around and north of the KDAY area. As the
atmosphere warms and becomes unstable, there should be scattered
thunderstorms across the region. So started the tafs off with a
VCSH at 13-15z, then transitioned VCTS by 15-17Z. Threw in a
tempo TS at TDAY from 15-19Z to cover the best chances.
The H5 low, will continue to work towards the fa during the day
Monday, but it will be filling. This means weakening lift by
late afternoon, so transitioned back to VCSH for the end of the
taf period.
OUTLOOK...Thunderstorms possible Monday night into Tuesday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Hickman
NEAR TERM...Sites
SHORT TERM...Hickman
LONG TERM...Sites
AVIATION...Sites
Area Forecast Discussion
National Weather Service Northern Indiana
737 PM EDT Sun Aug 27 2017
.SYNOPSIS...
Issued at 338 PM EDT Sun Aug 27 2017
Low pressure is expected to drop slowly southeast from the upper
Midwest tonight and Monday, then east across our area Tuesday.
This system will bring an increasing chance of showers into the
area tonight, with scattered showers and thunderstorms expected
Monday and Tuesday. Isolated showers are still possible over
eastern portions of the area Wednesday as the low moves away and
weakens. A cold front is expected to move across the area
Wednesday night and Thursday bringing a low chance of showers,
followed by cool and dry conditions Thursday night and Friday as
high pressure moves east across the Great Lakes.
&&
.UPDATE...
Issued at 720 PM EDT Sun Aug 27 2017
Initial band of showers/isol thunder was attempting to work east
to impact NW parts of the forecast area. However, surface
observations should little if anything reaching the ground at this
point and back edge of radar returns look to be eroding leading
to a low confidence forecast into this evening. HRRR attempts to
expand coverage and even brings activity well into eastern areas.
As a result, will continue to monitor, but make no changes.
Equally unsure as to how overnight will unfold with new convection
developing from central WI into eastern Iowa. Increase in pops
may be needed if this can expand and better organize
Otherwise did some minor adjustments to cloud cover.
&&
.SHORT TERM...(This Evening through Monday)
Issued at 338 PM EDT Sun Aug 27 2017
Moisture contg to slowly increase across our area from the top
down within w-sw flow aloft ahead of upr low dropping slowly sse
from ne MN. Shrtwv rotating around the low will move east across
IL tonight and then ne across our cwa Monday, likely accompanied
by at least sct showers. Fairly steep mid level lapse rates
initially tonight could support isolated thunderstorms, but
chances still too low to add mention to fcst. Better chc of
thunderstorms Monday with diurnal heating allowing for a little
more, though still weak airmass destabilization. Cloud cover
expected to limit diurnal temp ranges somewhat in this period with
lows tonight fcst near 60 and highs Monday in the mid 70s.
&&
.LONG TERM...(Monday Night through Sunday)
Issued at 338 PM EDT Sun Aug 27 2017
Sct showers and a few tstms expected to cont Mon night as upr low
approaches and continues Tue as low moves slowly east across our
area. Wk wind flow beneath the upr low combined with moist
airmass and moderate diurnal instability could result in some
funnel/landspout activity Tue aftn. Upr low should move east of
the area and shear out Tue night, though, wk trailing shrtwv in nw
flow behind it could spark a few showers eastern portion of cwa
Wed. Tail end of cdfnt associated with stronger shrtwv movg across
se Canada/U.S. should move across our cwa Wed ngt/Thu with wk
forcing/instability and limited moisture supporting 15-30% chc of
showers. Strong sfc high movg across the upr grtlks behind this
front should provide mainly clear skies with blo normal temps in
our area Thu ngt-Fri.
As usual, by days 6-7 medium range model`s solutions diverge
significantly with poor run-run continuity yielding considerable
uncertainty in the fcst attm. Latest GEM/ECMWF suggest to varying
degree that shearing out remnants of T.S. Harvey will lift ne
into or through the OH Valley this weekend with associated showers
psbly reaching our area. By Sunday-Monday GFS/ECMWF
digging nrn stream shrtwv into or toward the upr Grtlks with
accompanying cdfnt apchg our area though considerable timing
differences, while Canadian lingering Harvey remnants over the OH
valley with more subdued nrn stream. Attm, opted for a dry fcst
Sat with 20-25% chc of showers by Sunday aftn with temps returning
to at or slightly above normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 720 PM EDT Sun Aug 27 2017
Will continue with VFR conditions through the period with some
potential for a few showers after 6Z at KSBN and more towards
morning at KFWA. Lots of uncertainty as to how precip may unfold
with upstream appearance not overly impressive. Better chance for
some impacts arrives at KFWA after 18Z Mon.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
UPDATE...Fisher
SYNOPSIS...JT
SHORT TERM...JT
LONG TERM...JT
AVIATION...Fisher
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Area Forecast Discussion
National Weather Service Lubbock TX
859 PM CDT Sun Aug 27 2017
.UPDATE...
Quick update issued to adjust precip chances for tonight. Based on
latest guidance handling of MCS up in the Panhandle, rain chances
have shifted to the west. Will trim PoPs northeast and extend and
increase into chance category across the northwest.
&&
.PREV DISCUSSION... /issued 612 PM CDT Sun Aug 27 2017/
AVIATION...
VFR conditions to continue this evening. Models are showing
convection in the Panhandle dying out before pushing into the LUB
forecast area. Should it hold on, PVW and CDS would be the most
likely to be affected but not until around midnight. Confidence in
this happening is too low for TAF mention, though. A northerly
wind shift will occur after 1 AM, but it will be barely noticeable
as winds are expected to remain below 6 KT.
PREV DISCUSSION... /issued 300 PM CDT Sun Aug 27 2017/
DISCUSSION...
Hi-res models such as the HRRR and Texas Tech WRF show convection
pushing into the FA later tonight along an outflow boundary that is
currently stalled across northern OK and southwestern KS. Given
subsidence aloft and the lack of any discernible weakness in the
upper ridge the main forcing mechanism appears to be the boundary
itself. Surface moisture continues to remain in place across the
region leaving little effort for at least rain showers to develop. A
separate front is currently stalled across northern KS behind the
outflow boundary and is progged to push into the FA by tomorrow
giving one last chance for rain for the coming week.
Models are starting to agree with the future progression of the
remnants of Harvey by bringing it north to northeastward to the
Arklatex region later this week. For the most part this will keep
the FA under dry air and subsidence. The GFS keeps the remnants of
Harvey far enough westward by the weekend to give the Rolling Plains
a chance for rainfall. The ECMWF, however, keeps Harvey further
eastward closer to southern AR/northern LA which would keep the
Rolling Plains dry. The final path will be determined by how much
the Hudson Bay Low amplifies. The ECMWF has a much more pronounced
amplification which pulls Harvey northeastward.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
07/74
Area Forecast Discussion
National Weather Service Memphis TN
913 PM CDT Sun Aug 27 2017
.UPDATE...
At 9 PM CDT a calm evening is ongoing across the Mid-South.
Temperatures are in the low 70s to low 80s, but on track to
overnight lows in the upper 60s to lower 70s. Mid to upper level
clouds have been present over much of the region this evening,
and some shower activity continues over the southern portions of
the FA. This activity will likely continue into the night. The
forecast is currently on track, and no updates are necessary.
ZDM
&&
.PREV DISCUSSION... /issued 254 PM CDT Sun Aug 27 2017/
DISCUSSION...Surface analysis this afternoon places Tropical
Storm Harvey near Victoria, Texas while a weak cold front is
located over portions of Iowa and Kansas. Some moisture from
Harvey has made its way into the Mid-South with regional WSR-88D
radars indicating the development of showers and thunderstorms
mainly across portions of South/East Arkansas and North
Mississippi. As of 2 PM CDT, temperatures across the Mid-South are
in the 80s across most locations.
Short term models including the HRRR indicate the potential for
some isolated to perhaps scattered showers and thunderstorms to
continue for the remainder of the afternoon into tonight.
Convective coverage is anticipated to increase towards Monday
morning as a weak shortwave trough and associated cold front
drops into the Lower Mississippi Valley for Monday and Tuesday.
Isolated to scattered shower and thunderstorm chances are
anticipated to linger across the Mid-South through mid-week as
this front weakens further across the region.
Latest 12Z long term model trends indicate the future remnants of
Tropical Storm Harvey will be located somewhat east of earlier
forecasts. Interestingly enough the 12Z ECMWF quickly moves the
remnants over the Mid-South by Friday/Saturday and gradually
departs towards the end of next weekend. This would suggest a
potential for heavy rainfall perhaps late this week into the
upcoming weekend if current model trends persist and inclusion
into the hazardous weather outlook.
CJC
&&
.AVIATION...
00Z TAFs
Midlevel VFR ceilings to continue through this evening and
overnight. Isolated -SHRA will prevail mainly south and west of
MEM.
Latest few runs of the HRRR model depict a low level convergence
zone from MEM to MKL on Monday, with -SHRA forming as early as
15Z. Some thunder will be possible later in the afternoon, given
sufficient surface heating. Otherwise, status quo on Monday, with
VFR cigs and light surface winds.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
732 PM EDT Sun Aug 27 2017
.SHORT TERM...(This evening through Monday)
Issued at 406 PM EDT SUN AUG 27 2017
WV imagery and RAP analysis indicated a mid/upper level low near
KDLH, resulting in cyclonic srly flow through the cwa. a shortwave
trough near the WI/MI border supported a couple of bands of showers
through the cntrl and ern cwa along with a smaller area of tsra
lifting into Marquette county where MUCAPE values were in the 500-
800 J/Kg range. Additional weak shrtwvs were located upstream from
MN into wrn WI. At the surface, an occluded front extended southward
from low pres over the MN arrowhead.
Tonight, Models suggest that as the mid level low slowly moves into
sw WI the moisture advection and weak to moderate 850-500 qvector
conv will diminish with decreasing shra coverage. MUCAPE values
should remain high enough this evening to support a few tsra but
will drop off overnight with any isold tsra mainly over the far
south.
Monday, isold/sct shra are expected to linger over cntrl Upper
Michigan with an inverted sfc trough extending northward from the
low sagging into nrn IL and the possibility of another weak shrtwv
rotating into the area. MUCAPE values may also be high enough to
near 500 J/Kg again to support some isold tsra by afternoon with
pcpn coverage increasing.
.LONG TERM...(Monday night through Sunday)
Issued at 324 PM EDT SUN AUG 27 2017
Only weather resembling anything significant in the long term is
cold/frost potential Wed night and more so Thu night when skies will
be clear and winds light. That is the only part of the forecast
where grids were changed from the blended initialization, in which a
50/50 blend of BCCONSAll and WPCGuide was loaded for min temps.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 732 PM EDT SUN AUG 27 2017
MVFR conditions will gradually degrade to IFR ceilings and
occasionally visibilities tonight as showers dissipate and fog
develops overnight. While there will be some improvement Monday
morning, VFR conditions will not return until after 18Z at KCMX and
KSAW and until late in the forecast at KIWD.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 406 PM EDT SUN AUG 27 2017
Southeast winds to near 30 knots late today will diminish to 15 to
25 knots tonight as low pressure weakens and sags to the south.
Winds will then remain below 20 knots through the rest of the
forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 8 PM EDT this evening for MIZ014.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Titus
AVIATION...RJT
MARINE...JLB
Area Forecast Discussion
National Weather Service Omaha/Valley NE
754 PM CDT Sun Aug 27 2017
.UPDATE...
Issued at 752 PM CDT Sun Aug 27 2017
Added a slight chance of showers and rumbles of thunder to western
IA through the evening. Couple of showers out there now attached
to vort lobe as shown on water vapor imagery, and latest HRRR
model continues to move these south through our western IA
counties.
Isolated thunderstorms in southeast NE have now moved into
northeast KS, so that area should remain dry.
&&
.SHORT TERM...(Tonight through Wednesday)
Issued at 313 PM CDT Sun Aug 27 2017
Mainly dry and continued cool weather is expected through mid week.
Strong vorticity maximum rotating around upper low in northern
Minnesota dived through central Nebraska overnight and this morning,
triggering a line of wind-producing thunderstorms across central and
a small part of eastern Nebraska. System was currently moving off to
our southeast, taking precipitation and associated cloud cover with
it. Another weak mid level wave rotating through western Iowa this
afternoon was helping to steepen lapse rates in that area, leading
to some broken cumulus cloud cover. A few showers may result from
this instability, but precip and cloud cover should be quick to
dissipate with sunset and loss of surface heating.
Then surface high pressure is forecast to settle south across the
region tonight and linger into Tuesday. Cool and dry north through
east low level flow is expected during this time, keeping
temperatures on the cooler side of normal under mainly clear skies.
By Wednesday, sprawling ridge in the western U.S. will drift a
little east, allowing for warmer air to spread through central
Nebraska and into western sections of our CWA. Also, lowering
surface pressures in the High Plains will promote return flow to
parts of eastern Nebraska at that time, but robust moisture return
will be held in check as surface high ridges into the Southern
Plains and effectively cuts off Gulf moisture.
So temperatures will start off in the upper 70s or lower 80s for
highs Monday, gaining a category or so each day, putting highs
closer to the middle 80s by Wednesday. Most lows should average 55
to 60 each morning.
Also of note, with high pressure overhead tonight, diminishing winds
and cloud cover will allow temperatures to drop to well below
afternoon UPS crossover temperatures, suggesting areas of fog are
likely overnight and Monday morning. However drying low levels and
some mixing with winds only slowly diminishing may limit reduced
visibilities in some areas. Still have enough confidence to mention
areas of fog in grids.
.LONG TERM...(Wednesday night through Sunday)
Issued at 313 PM CDT Sun Aug 27 2017
The mainly dry weather pattern will likely hold through the end of
the week and into next weekend. Upper ridging in the West will get
suppressed south as longwave trough moves onto the Pacific Northwest
coast Wednesday and into the Northern Rockies on Thursday. This wave
will dampen as it moves into the Plains, with models suggesting only
a minor shortwave tracking across the Dakotas and Nebraska Thursday
night and Friday. A weak frontal boundary will follow that wave,
settling across Nebraska and Iowa on Sunday. Varying model solutions
hint at sporadic chances for showers with shortwave energy Thursday
night and Friday, then with frontal system on Sunday. While upper
flow pattern is handled similarly between most long range output,
little consistency is offered regarding finer details and resulting
precipitation. Thus the best course of action at this time is to
maintain status quo and not change much from our current forecast of
mainly dry and temps in the 60s/80s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 607 PM CDT Sun Aug 27 2017
There area a couple of showers/thundershowers in the area, but not
expected to impact any TAF sites. VFR conditions at both
KOMA/KLNK, but some MVFR fog could develop at KOMA 11-13z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
UPDATE...DeWald
SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...DeWald
Area Forecast Discussion
National Weather Service Phoenix AZ
303 PM MST Sun Aug 27 2017
.SYNOPSIS...
Above normal temperatures will continue this week as strong high
pressure remains firmly entrenched over the interior West. A
modest increase in moisture levels is anticipated today and could
result in an uptick in thunderstorm activity this afternoon and
evening, mainly east of the Phoenix area. Thunderstorm chances
will remain limited across the lower deserts into the middle of
this week, with the possibility of cooler temperatures and
increasing moisture across the region by next weekend.
&&
.DISCUSSION...
Rest of Today and Tonight...
Storm activity early this afternoon is indeed looking quite
similar to 24 hours ago with a bit more coverage over Yavapai
County. HRRR has been pretty consistent in depicting storm
activity the rest of the afternoon playing out quite similarly to
yesterday with storms forming over moving toward the lower
elevations of northeast Maricopa County (metro Phoenix) and
Northern Pinal County late this afternoon but struggling to
maintain themselves. In the process however, strong winds can be
expected. Other CAMs such as NAM Nest and UofA WRF- GFS are not
quite as enthusiastic. Of note though, the 18Z NAM Nest has more
activity than it`s 12Z run. With the winds will be potential for
blowing dust but anticipate the fetch of the winds will not be
over prime dust generating areas. Thus expect reduced visibilities
will not be like a classic dust storm situation but enough to
insert mention of patchy blowing dust for metro Phoenix and
northern Pinal County. There is also potential for heavy rain but
expect it will be quite isolated and be more likely to occur
over/near foothill areas. Otherwise, don`t expect much in the way
of precip with this first round of convection. CAMS also depict a
follow-on batch of weaker showers moving through south-central
Arizona this evening. Some of the solutions show these showers
making it west of the Lower Colorado River Valley by 12Z. Overall
though, they won`t add up to much. This nocturnal activity appears
to be associated with a slow moving short wave depicted by the
RAP. Even the GFS indicates some sort of disturbance moving
through tonight but it seems to originate with model convection
over NE New Mexico.
Monday through Wednesday...
The high remains centered to our north with an easterly component
to the steering flow. However, drier continental air begins moving
in and thus, anticipate a bit of a downtrend in convective
activity. For a large part of our area (SE AZ and far SE CA),
convection related hazards will not be a factor but rather heat is
the issue. With no real downtrend in temps expected, extended the Excessive
Heat Warning for much of SW AZ and our part of CA through
Wednesday.
Thursday through Sunday...
Things may get a little more interesting into next weekend, as
models are fairly consistent showing a tropical system approaching
the tip of Baja by Thursday, and slowly moving
west/northwestward, potentially spreading a plume of moisture
northward into the Southwest. Also of interest, there is the
possibility that mid-level moisture associated with the remnants
of Harvey could get caught up in easterly flow aloft, and move
westward across west Texas and northwest Mexico. While uncertainty
surrounding each of these scenarios and the overall large-scale
pattern is still high, it still bears worth watching for
associated impacts of increased rainfall/thunderstorm potential.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
Storms currently forming in Gila County are expected to move down
near the TAF sites late this afternoon/early evening and
dissipate as they do so. Despite weakening storms in the valley,
outflow winds will still be a concern favoring the east to north-
east direction. Currently have outflow winds in the TAFs but no
blowing dust as there is low confidence that will actually happen.
Light and isolated showers may linger through late tonight before
dissipating. Very similar conditions are expected tomorrow with a
chance of afternoon/evening thunderstorms.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns for the next 24 hours as winds generally
remain south at KBLH and from the southeast at KIPL. There is a
chance winds may switch west to southwest at KIPL late this
evening but confidence remains low on that particular solution.
Skies will remain mostly clear.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday:
Storms will generally stay confined to the mountains through our
extended period although late afternoon storms in and around
Maricopa County, especially those locations near the valley`s
edge, is certainly not out of the question. SE California is
expected to remain dry. Minimum afternoon humidity will vary
between 15-20% for the lower elevations while temperatures will
remain above average through at least Thursday. Winds will remain
light and typical for this time of year although outflow winds
generated from nearby thunderstorms will be gusty and erratic.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Wednesday for AZZ530-532-
533-536.
CA...Excessive Heat Warning until 8 PM PDT Wednesday for CAZ561-563-
565>570.
&&
$$
Visit us on Facebook, Twitter, and at weather.gov/phoenix
DISCUSSION...AJ/Rogers
AVIATION...Wilson
FIRE WEATHER...Wilson
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Monday)
Issued at 242 PM CDT Sun Aug 27 2017
The morning MCS has moved through the area with only a few showers
left in east central KS. The synoptic cold front resides somewhere
around the I-70 corridor and is forecasted to continue southward
through the evening although the convergence appears rather weak.
Strong cin has been left in the wake of the MCS, so additional
development along the front seems unlikely. A majority of the models
keep the area try with only a few solutions showing an isolated
shower or storm through early evening. Dry air will slowly filter
into the area, so once temperatures cool after sunset fog might be
possible especially under clear skies. Overnight the surface ridge
stays west and north, so calm winds seem unlikely across eastern KS
therefore the boundary layer could stay partially mixed. The RAP
soundings show fog developing in the late evening before the
advection increases behind the front mainly across east central KS.
This is also where a majority of the high res models show the fog
potential. Regardless patchy fog may be possible late this evening
and overnight. With northerly flow aloft the surface high pressure
builds into the forecast area tomorrow with highs approaching lower
80s.
.LONG TERM...(Monday night through Sunday)
Issued at 242 PM CDT Sun Aug 27 2017
Upper troughing occurs across the Great Lakes while expansive ridge
builds over the western CONUS results in northeast Kansas remaining
on the dry and mild side. A weak embedded shortwave trough attempts
to develop light qpf over the central Plains Wednesday night,
however with much of the available moisture focusing with remnants
of Hurricane Harvey, kept a dry forecast through the weekend.
By Friday night into Saturday, the remnant moisture and convection
associated with Hurricane Harvey begins to lift northward. Dependent
on the timing of a passing upper trough over the Great Lakes region,
a few showers and thunderstorms may impact areas of southeast Kansas
and southern Missouri. The GFS is slower with the timing of the
upper trough and therefore brings more precipitation into southern
Kansas for the weekend. With the high uncertainty, have left a
slight chance mention on Friday night, with optimal chances residing
in Oklahoma and Missouri.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 622 PM CDT Sun Aug 27 2017
For the 00z TAFs, showers near KMHK will continue to track further
south early this evening, with dry conditions expected through the
TAF period. The main concern will be for the potential of patchy
fog development a few hours before sunrise, as a result of the
recent rainfall and the light and variable winds in place. This
patchy fog may result in MVFR vis conditions through sunrise, and
cannot rule out the possibility of some lower vis conditions near
KTOP/KFOE. Once the fog dissipates Monday morning, expect VFR
conditions for the remainder of the day.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Sanders
LONG TERM...Prieto
AVIATION...Hennecke
Area Forecast Discussion
National Weather Service Tucson AZ
903 PM MST Sun Aug 27 2017
.SYNOPSIS...A low grade monsoon pattern will prevail through much
of the coming week. Adequate moisture will produce isolated to
scattered mainly afternoon and evening thunderstorms, with the
greatest coverage east of Tucson and tending to favor mountains.
An increase in moisture may bring a corresponding increase in
thunderstorms over the weekend or early next week. Daytime
temperatures will be above seasonal normals through much of the
week.
&&
.DISCUSSION...Another strong and organized outflow from the
Mogollon Rim this afternoon. The big difference for most of our
area compared to yesterday is a drop off in available moisture. A
brisk easterly flow imported precipitable water values below 1
inch from southwest New Mexico into southeast Arizona, with the
00Z KTWC sounding coming in at 0.87 inches. As such, eastern
portions of the outflow did little more than generate gusty winds
and dust, with most of the benefit from the extra lift felt in
areas north and northwest of Tucson. The sun`s down and the
outflows are pushing into lower desert locations, so expect a
general clearing trend overnight. Please see the previous
discussion below for additional details beyond tonight.
&&
.AVIATION...Valid thru 29/06Z.
Clearing overnight with Isold -TSRA/-SHRA mainly N-NE of KTUS
again after 29/20Z. Otherwise VFR conditions. SFC wind E-SE 5-15
kts with localized gusts to 20 kts. Aviation discussion not
updated for TAF amendments.
&&
.FIRE WEATHER...Easterly winds will prevail across the region
thru much of the week. They will be enhanced later tonight into
Monday where 20-foot winds speeds will be 12-17 mph with gusts of
15-25 mph. Isolated showers and thunderstorms will be around
through Thursday with an uptick in areal coverage possible next
weekend or early next week.
&&
.PREV DISCUSSION...A strong ridge north of our area (over the
central Great Basin) is dominating our weather. An easterly to
northeasterly flow around this feature is bringing in a little bit
of drying this afternoon, but all is not lost. The rim is quite
active with a more organized outflow than I expected pushing into
northern Graham county. Above average height and thickness values
from the ridge means above average heat as well. Latest HRRR
trends hinting at a few storms around the area this afternoon
after all.
With troughiness upstream through eastern states, we`ll keep a
ridge centered north of our area through most of the coming week.
In general that will mean a low grade monsoon forecast, with the
exception of one or two afternoons with stronger outflows off the
rim providing extra lift (Tuesday?).
It`s that time of year though. As we head into September we`ll
start staring harder at the tropical Eastern Pacific. NHC has some
organization likely just south of Baja in the next several days
(probably around mid week). Ensemble means and model consensus
showing fairly good agreement (for this far out) in bringing a
tropical storm northward over or just west of the southern Baja
Peninsula Friday, then near central Baja over the weekend. That
would at least help push a deep surge of moisture northward late
next weekend or early next week. Something to keep an eye on.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Meyer
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