Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/22/16
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
552 PM MDT WED SEP 21 2016
.AVIATION...
00Z TAF CYCLE
Showers and thunderstorms are smattered across northern and
central NM early this evening and are rapidly moving
northeastward. Some storms thru the eve may produce wind gusts to
40-45kts. Storms across the plains should diminish with sunset,
though across central NM, storms may linger to 06Z or thereabouts.
Some areas of MVFR cigs are possible overnight, particularly
across far NW NM toward sunrise, but not too confident it will
occur. Another round of storms will develop on Thursday favoring
areas btw the ContDvd and the east slopes of the Central Mtn
Chain. Additionally, breezy to locally windy conditions will
develop by early afternoon. Wind gusts between 25 and 30kts will
be common through early eve.
34
&&
.PREV DISCUSSION...319 PM MDT WED SEP 21 2016...
.SYNOPSIS...
Scattered showers and thunderstorms will move northeast across New
Mexico through Friday. Some of the stronger storms may produce brief
strong wind gusts and perhaps some small hail. Temperatures will be
above normal in many areas through Friday before a strong cold front
surges through the state by late in the day. Low temperatures will
be the coldest since last spring for much of the state. Lows will
range from the 20s and 30s across the northern and western high
terrain to the 40s and 50s across the eastern plains. Temperatures
will likely stay cooler through early next week with a chance for
some showers across the eastern half of the state.
&&
.DISCUSSION...
The remnant upper level wave from what was formerly Hurricane Paine
is shifting quickly northeast across NM this afternoon. It`s low
level center dissipated off the northern Baja and any moisture that
was associated with it has been washed out across a vast area of the
southwest CONUS. Enough forcing is present aloft to combine with
afternoon heating for a decent crop of storms around the central and
western high terrain. Activity is cruising along and has potential
to tap stronger winds aloft. Strong outflow winds and perhaps some
small hail are possible with any of the stronger storms. The latest
HRRR and SPC SSEO merges convection into an area over the San Juan
Mts and the RGV this evening. Thursday is expected to be a repeat of
today with perhaps a better focus along and west of the Cont Dvd.
Friday will be a dynamic day across NM as a potent Pacific cold
front surges southeast through the area. High temperatures will
still be quite warm ahead of the front. Veering wind profiles and
abundant moisture still in place over the region should allow for
at least a thin line of storms along the main frontal forcing. 12Z
guidance is still paltry with precip development and has actually
trended drier than previous runs. Will maintain chance POPs for now.
700mb temps fall from near +14C to around +4C behind the front.
This strong cold advection along with impressive dry air advection
will lead into the coldest night since last spring for much of the
state. Folks around Farmington will want to keep a close eye on the
min temp forecast as we are currently advertising 35F. Sheltered
areas that are typically colder may see their first freeze.
Overall Saturday appears to be a tranquil day with cool northwest
flow over the state. Max temps will be 10 to 20F colder than Friday.
The upper level trough is now shown by most of the 12Z guidance to
push slowly east away from the area while developing into a large
scale upper low over the Great Plains. This is yet another change in
the outlook so confidence remains low. Nonetheless, temps will stay
cooler through early next week with the greatest potential for any
precip over the east.
Guyer
&&
.FIRE WEATHER...
Moisture levels surface and aloft considerably higher today than
on Tue thanks in large part to moisture shunted northeast from
the remnants of once Hurricane Paine. Enough sunshine has
materialized to generate some spotty showers and thunderstorms
across roughly the nw half of the fcst area. More isolated
activity struggling to keep going just east and ne of the
Sacramento mtns. Majority of the storms should be able to manage
wetting rainfall.
On Thu this moisture will begin to yield a bit to a drier sw flow
out ahead of a deepening trough aloft moving into the Great Basin.
Winds through a deep atmospheric layer over NM will be picking up
as the upper trough and associated Pacific cold front approach.
Lee side surface troughing across the east Thu will encourage
development of breezy to locally windy conditions most areas by
aftn. Despite some modest drying in the atmosphere Thu there will
still be a decent chance of a few showers and storms mainly to the
west of the eastern plains thanks to the dynamic forcing of the
approaching trough. The main Pacific front should push into and
through NM between late Thu night and Fri but moisture will be
less Fri than Thu so fewer wetting showers and storms are
expected, especially east of the Continental Divide. High temps
behind the front across nw and west central NM will be a few to
around 10 degrees below seasonal normals.
With passage of a pretty healthy back door front Sat night and Sun
daytime temps will be below normal pretty much all across the area.
Chances for wetting rain later in the weekend and early next week
still look to be less than what appeared would be the case a day or
two ago, though eastern areas still have a pretty good chance. a
developing closed low over to just west of the state looks a little
less likely now than was the case over 24 hours ago. In fact by mid
to late week next week daytime temps may head back well above
normal. The Canadian fcst model though is still holding to a
somewhat weaker upper low or deep trough hanging out over the state
so dry and warmer for this time period not certain yet by any means.
43
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service La Crosse WI
645 PM CDT Wed Sep 21 2016
.SHORT TERM...(This evening through Friday)
Issued at 358 PM CDT Wed Sep 21 2016
Rain...rain...go away! Unfortunately that doesn`t seem very likely
as we wrap up the work week, with the main forecast concern being
timing, placement, and amounts of additional heavy rainfall...not to
mention the potential for severe storms into this evening. Midday
analysis places a warm front just touching our far southwestern CWA,
slowly bowing northward courtesy of diurnal mixing, with dew points
making a sizable jump toward the lower 70s west of the Mississippi
River. In the presence of quite steep low/mid level lapse rates,
that added moisture has led to CAPE values surging into the 3000+
J/kg range, with all focus for the next couple of hours on the
potential for severe storms. Overall deep shear isn`t terribly
impressive, but 0-1/0-2km shear is rather impressive in the 30-40
knot range, with good turning right along the warm front. Given
lower LCL heights and said shear, can`t at all rule out a few
tornadoes developing the next few hours, in addition to the
potential for some pretty large hail given normalized CAPE values of
around 0.4...indicative of some impressive instability. Could see
individual storms merge into more of a cluster with time with
perhaps an increasing wind threat.
Not to be forgotten, the even larger issue in the longer term
remains heavy rain potential into tonight and perhaps much of
Thursday as well. Approach of our next ripple in the flow and
associated even deeper surge of tropical moisture from the remnants
of Paine should work in tandem with another nocturnal increase in
low level jet forcing/moisture transport to deliver another
expanding axis of convection somewhere across the area. That
"somewhere" may ultimately be just a touch farther north than seen
last night as the better mass convergence focuses initially
along/north of I-94, but with hints among recent runs of CAM
guidance that we will see another southward drift with time - in
line with Corfidi vector propagation. Given PWAT values near the top
of the chart for late September and the tropical tap/strong elevated
instability/3-4km warm cloud depths, don`t have any reason why
storms won`t produce another 2-3 inches where they persist, with
localized amounts again up to 5 inches as noted with last night`s
convection. Of course, exact placement is all but impossible to nail
down even at this hour, but suffice it to say flash flooding
concerns remain high, especially with many areas primed last night
with heavy rains.
Beyond tomorrow morning, don`t have the best feeling how things will
play out, but with the warm frontal boundary still draped nearby and
persistent lift/instability near that feature, can`t at all rule out
periods of showers and storms hanging tight through Thursday night
and even into Friday. Should see southern areas increasingly become
capped with time into Friday as upper troughing digging through the
Rockies builds sharp ridging aloft across the Mississippi valley.
.LONG TERM...(Friday Night through Wednesday)
Issued at 358 PM CDT Wed Sep 21 2016
Looking like the active weather pattern will continue into early
next week, with quite the upper trough (very fall-like) progged by
the majority of medium range guidance to work east through the
Plains into Saturday. Modest height falls, upper divergence, and
enhanced jet help should ignite yet another axis of showers and
likely some thunder across much of the region into Saturday night,
with some potential for severe storms pending timing given increased
shear aloft. There remains some question about how fast this system
will progress, with the ECMWF steadfast in its idea of a much slower
progression as more energy rounds the trough base and works a
frontal wave through the area toward Tuesday or Wednesday. The GFS
meanwhile also remains steadfast with its faster solution and a much
farther north closing off of an upper level low into early next
week. At this point, don`t have any reason to go one way or the
other but the overall idea is still for continued rain chances at
various times, with perhaps a trend toward much cooler conditions
toward midweek. Will have to watch this pattern closely as the last
thing we need here is additional heavy rainfall (or any rain for
that matter), and the potential is there for another bout of
widespread heavier precipitation into the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 645 PM CDT Wed Sep 21 2016
Convection continues to expand north of the warm front over
northern Iowa. The latest run of the HRRR lifts this northeast and
into KRST early this evening with MVFR conditions possible. More
activity expected to develop along the nearly stationary cold
front that extends from southwest Minnesota into northern
Wisconsin as the low level jet impinges on it. This should bring
a line of storms south into both airports overnight with IFR/MVFR
conditions expected. Once this line moves by, some suggestion by
the hi-res meso scale models that the rest of Thursday could then
be dry. For now will go with VFR conditions behind the line of
storms with VCSH in the event it does not end up being all that
clean.
&&
.HYDROLOGY...
Issued at 358 PM CDT Wed Sep 21 2016
Plenty of water yet to come per our current forecast, with flash
flooding concerns first and foremost the main concern overnight.
Many spots along and either side of the Mississippi picked up a
solid 2-4 inches overnight with some flash flooding/mud slides
noted. Additional forecast rainfall of 2-3 inches with localized
much higher amounts under any training storms should have little
trouble producing additional flash flood concerns tonight, though
the exact location of heaviest rain does remain somewhat in
question.
Looking longer term, river flooding on most if not all river
systems will become a bigger issue the next few days, with hints
that we may well see another bout of heavy rain later Saturday
into Sunday. We definitely don`t need that, but given the setup,
don`t be shocked to see upward trends on river forecasts over the
next couple of days.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Flash Flood Watch through Thursday evening for WIZ017-029-
032>034-041>044-053>055-061.
MN...Flash Flood Watch through Thursday evening for MNZ079-086>088-
094>096.
IA...Flash Flood Watch through Thursday evening for IAZ008>011-018-
019-029-030.
&&
$$
SHORT TERM...Lawrence
LONG TERM...Lawrence
AVIATION...04
HYDROLOGY...Lawrence
Area Forecast Discussion
National Weather Service Cleveland OH
919 PM EDT WED SEP 21 2016
.SYNOPSIS...
High pressure will remain in control of the weather across the
region into Thursday. A cold front will move into the Great Lakes
on Friday then sag south of the area by Friday night. A cooler
Canadian high pressure will arrive Saturday into Sunday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
High pressure located over the central SOuthern Tier of NY will
remain strong enough to keep the showers and thunderstorms well
west of the County Warning Area through the night.
Only minor changes to cloud cover and hourly temperatures were
made to reflect current trends.
Previous Discussion...
A few clouds around this evening...primarily across northern OH
and nw PA. Some of this is afternoon cumulus which will fade
quickly late this afternoon. The mid/high clouds emanated from a
decaying MCS across MI this morning. They should drift across the
lake this evening. Although it cannot be ruled out
entirely...current satellite trends do not look favorable for
shower/ts development across southeast MI...so Toledo and across
the lake should stay dry. HRRR only guidance showing development
early this evening. Otherwise another quiet night with high
pressure overhead. Temperatures will be running above normal
tonight...but still a number of inland locations will get into the
50s.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
Pattern begins to amplify for the remainder of the week. While an
upper low takes up the Rockies/West Coast and ridge will build
across the Mississippi Valley. Precipitation Thursday will remain
north of the area along stalled frontal boundary across the Great
Lakes. This will provide yet another day with temperatures well
above normal. For reference...normals have now dropped into the
lower 70s.
A shortwave across central Canada will carve a trough across New
England and bring the Great Lakes front southward. This front has
the cooler weather bottled up to its north...so with its passage
Friday temperatures will be brought back closer to normal going
into the weekend. We will still likely reach and top 80 degrees
Friday. Saturday all will be in the 70s with some upper 60s likely
for highs across nw PA and a north-northeast flow. Little has
changed with the outlook for precipitation with this front.
Moisture and lift limited. Will continue with silent 20 percent
chances Friday into Saturday.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A rather substantial shift in the long range models is noted over
the last 24 hours with a trend towards an upper level low closing
off over the plains states. This blocking pattern would support a
high amplitude ridge building back into the Great Lakes Region with
temperatures trending warmer through the extended. Models had shown
this blocking pattern last weekend and feel the shift back to it is
supported by the strong upper jet over the North Pacific. With that
said, started trending the forecast drier and warmer during the
early part of next week. This pattern shift will need to continue to
be monitored on later model cycles.
&&
.AVIATION /00Z Thursday THROUGH Monday/...
VFR conditions with only cirrus will continue through the
overnight. Expect patchy mvfr br toward daybreak.
OUTLOOK...Some MVFR possible Saturday night in scattered shra/tsra.
&&
.MARINE...
A ridge over the eastern Great Lakes will shift south and weaken
through the end of the week. A weak area of low pressure will pass
north of Lake Erie on Thursday with a weak cold front settling south
across the lake on Friday. Northeast winds of 10-20 knots will
develop behind the front Friday afternoon and night causing waves to
build to 2 to 4 feet into Saturday morning. High pressure will
strengthen over the eastern Great Lakes over the weekend maintaining
easterly winds on the lake.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Oudeman
NEAR TERM...Mullen/Oudeman
SHORT TERM...Oudeman
LONG TERM...KEC
AVIATION...DJB
MARINE...KEC
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
640 PM CDT Wed Sep 21 2016
.SHORT TERM.../This evening through Thursday/
Issued at 344 PM CDT Wed Sep 21 2016
The primary concern into tonight is obviously convective trends
include heavy rain and severe potential. The current Grinnell-Forest
City outflow boundary from morning convection continues to try and
initiate new convection but is having little luck sustaining
anything or anchoring to it. A detailed look at the cells and radar
fineline notes development on either side of the boundary suggesting
this is mainly elevated. Thus even though uncapped 3000 j/kg MLCapes
are in place just west of the feature there seems to be regarding rainfall
potential, precipitable water and warm cloud depth values are not
extreme, but seasonally high vs climatology promoting efficient
rainfall rates. The outflow boundary has reduced confidence in
high resolution solutions, but the HRRR, RAP and HopWRF had the
best handling on earlier Upper MS Valley convection and suggest
the northern few tiers of IA, eastward to the MS river could get
hit with heavy rains overnight with 15z ESRL HRRR amounts up to an
alarming 5-10 inches and the 15z HopWRF showing high neighborhood
probabilities of at least 5 inches over NE IA out of our forecast
area. Other models only show a few inches however, which is
possible if the stronger Corfidi vector movement makes the
convection too progressive north to south. So again it needs to be
emphasized that a very high impact event is certainly possible but
with somewhat diminished confidence due to model spread and
uncertainties.
Remember that this uncertainty is also carried over into the current
river forecasts which include 48 hours worth of QPF rather than the
typical warm season 24 hours. Current QPF depicts a widespread but
middle of the road 2-3 inches of rainfall affecting the Winnebago
and Cedar basins which results in moderate flooding in several
locations. Changes in location or rainfall amounts on either side of
that spread could result in lower or higher forecast stages. This is
why Hydrological Outlooks rather than warnings have been issued
until confidence in locations and magnitude increases.ow chances
of anything getting rooted surface based at the moment.
Convergence is shallow per the lack of 0-2km moisture convergence
and surface winds east of the boundary are veering suggesting a
downward trend in overall convergence. Some strong to severe
elevated storms are still possible however with higher effective
shear and ESRH still in place north and east of the boundary.
The question into tonight then turns to where new MCS development
will occur and its movement. Confidence is not the highest however
as none of the models are handling the strength of the outflow
boundary well. Examination of 305K isent surfaces show the NAM and
GFS focusing 30-40kts of flow and convergence from the Mason City
area into southern MN while the latest Rap washes this out more and
highlights MN. The latest objective analysis shows the 925/850mb
fronts and associated frontogenesis into MN so this would appear to
be the favored MCS genesis region. It does not mean IA will be
spared however. The strength of the inflow results in Corfidi
vectors with a pronounced southern motion suggesting the MCS will
eventually be drawn into IA. MUCapes of a few thousand should
persist into the night with around 30kts of effective shear
suggesting severe storms would remain possible with favorable shear
orientation north to south into IA.
.LONG TERM.../Thursday night through Wednesday/
Issued at 344 PM CDT Wed Sep 21 2016
Little change in going forecast for the next few days. Confidence in
overall trends for heavy rainfall potential remains high...but
details still debatable due to daily mesoscale interactions.
By early Thursday morning still expecting ongoing convection
across the north with old outflow boundary still the focus for
some thunderstorm activity over the north half of the forecast
area. Though the better forcing will be in the overnight period
tonight...there will still be enough instability during the
morning and afternoon hours to promote thunderstorms with locally
heavy rainfall potential over the north half of the forecast area.
Will maintain FFA across the area through tomorrow afternoon.
Through the night another strong push of thetae advection will
precede the next upstream wave propagating northeast by 12z
Friday. Most of any convection should be confined to the north
third Thursday night and north into Minnesota. With the boundary
holding on there will still be the potential for additional
locally heavy rainfall across the north. If trends continue...
there may be a need for an extension of headlines there. By 12z
Friday models push the warm front well into southern Minnesota.
This will temporarily limit convection over our area as all of the
forcing will be moving north. With the warm sector fully realized
once again Friday...highs will move back into the upper 80s to
lower 90s during the afternoon hours. Surface dew points will
again remain rather uncomfortable in the mid to upper 60s...with
heat indices well into the 90s by late afternoon. With the approach
of an upper level trough over the northern Plains Saturday a cool
front will move into the area by 12-18z. Models have advanced the
front a bit faster...though the boundary begins to slow as it
crosses the region from Sunday through Monday morning. Unfortunately...
the tropical moisture feed will remain intact just along and east
of this boundary. There is some uncertainty but if the boundary is
hung up long enough additional moderate to locally heavy rainfall
amounts of 1 to 2 inches may occur over the region between Saturday
evening and Monday morning...especially east of I35. The GFS and
Euro diverge thereafter...with the GFS focusing the boundary southeast
of the region from Monday through Wednesday. The Euro holds the boundary
over eastern Iowa and with a more northerly track of the northern
Plains system into midweek next week as well as a rather strong southern
stream H500 system developing by 12z Monday. The GFS has the northern
system looping back southeast by 00z into the Central Plains with
virtually no southern stream component at H500 at that time. The
result here is that the surface boundary and rain is pushed out of
the region by the GFS. For comparison...the GEM is even slower and
farther west than the Euro. At this time...will have to weight the
Euro/GEM solutions a bit higher and will need to closely monitor
trends through the weekend. If the latter proves a better solution...the
resultant rainfall over the region could additionally add several
more inches of precipitation on top of what is projected through
Monday. The reason...both the direct fetch from the Gulf and potential
for another old tropical system being injected into the area from
the southern Plains. Highs next week should be cooler with extensive
cloud cover and chances for rainfall.
&&
.AVIATION.../For the 00Z TAFS through 00Z Thursday evening/
Issued at 640 PM CDT Wed Sep 21 2016
Storms continue to form right near KMCW, so have continued the
mention of TSRA this evening. Looks like there should be a break
late this evening, before more storms form across southern MN and
drop southward impacting KMCW toward 06Z or so. Otherwise storms
moving southward may roll through the northern TAF sites and near
KDSM with lingering shower activity into Thursday. Winds remain
out of the south. Expect CIGS around MVFR to low VFR with the
storms.
&&
.HYDROLOGY...
Issued at 344 PM CDT Wed Sep 21 2016
Regarding rainfall potential, precipitable water and warm cloud
depth values are not extreme, but seasonally high vs climatology
promoting efficient rainfall rates. The outflow boundary has reduced
confidence in high resolution solutions, but the HRRR, RAP and
HopWRF had the best handling on earlier Upper MS Valley convection
and suggest the northern few tiers of IA, eastward to the MS river
could get hit with heavy rains overnight with 15z ESRL HRRR amounts
up to an alarming 5-10 inches and the 15z HopWRF showing high
neighborhood probabilities of at least 5 inches over NE IA out of
our forecast area. Other models only show a few inches however,
which is possible if the stronger Corfidi vector movement makes the
convection too progressive north to south. So again it needs to be
emphasized that a very high impact event is certainly possible but
with somewhat diminished confidence due to model spread and
uncertainties.
Remember that this uncertainty is also carried over into the current
river forecasts which include 48 hours worth of QPF rather than the
typical warm season 24 hours. Current QPF depicts a widespread but
middle of the road 2-3 inches of rainfall affecting the Winnebago
and Cedar basins which results in moderate flooding in several
locations. Changes in location or rainfall amounts on either side of
that spread could result in lower or higher forecast stages. This is
why Hydrological Outlooks rather than warnings have been issued
until confidence in locations and magnitude increases.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Thursday evening for IAZ004>007-
015>017.
Flash Flood Watch through Thursday evening for IAZ023>028-
033>039-044>048.
&&
$$
SHORT TERM...Small
LONG TERM...REV
AVIATION...Beerends
HYDROLOGY...Small
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1148 PM EDT WED SEP 21 2016
.AVIATION...
Remnant showers/thunderstorms are still expected to largely pass
north of the southeast Mi terminals overnight and this morning.
There is a small chance that a stray shower/thunderstorm may impact
MBS. Given the trends for convection to weaken as it approaches the
more stable mid level profile over Lower Mi, the chance of a
thunderstorm will continue to be left out of the MBS TAF.
Despite periodic high clouds traversing the area, boundary layer
moisture and radiational cooling have already led to some fog
development. This has been more extensive across the Saginaw Valley
where afternoon low level moisture advection was a little stronger.
Observational trends certainly support maintaining a mention of fog
in the terminals through daybreak. The likelihood of additional
cirrus debris advancing across the area during the early morning may
slow the pace of cooling and thus suggests refraining from going too
low with early morning visibilities just yet.
For DTW...
There was a weak southeasterly wind off Lake Erie this evening which
nudged sfc dewpoints up a little. The thicker cirrus should also
remain farther north and west. So radiational cooling will provide a
good chance for some MVFR type vsby in fog around daybreak.
//DTW Threshold Probabilities...
* None
&&
.PREV DISCUSSION...
Issued at 927 PM EDT Wed SEP 21 2016
UPDATE...
Radar/Satellite imagery indicates at least a couple short wave
featured across nrn Wisconsin. These impulses will track across
Upper Mi and the straits tonight into Thurs morning. This will
allow showers and a few thunderstorms to slowly extend from nrn
Wisconsin into northern Michigan, while the deeper convection
holds well west of the area within the quasi stationary convective
clusters across MN/IA/wrn Wi. There will remain a localized region
of mid level subsidence and associated drier mid level air across
Se Mi tonight well into Thursday. This should largely hold the
more organized showers and thunderstorms to the north and
northwest of the forecast area overnight and Thursday. Given how
far south some of the convection has developed in ern Wisconsin
this evening, it seems plausible that some stray showers/isolated
thunderstorms may impact the Saginaw Valley and tip of the thumb
overnight. This fully supports the low chance pop in the forecast
(along and north of a Saginaw to Sandusky line) overnight and
during the day Thursday. The only update to the forecast will be
to push the chances of rain back a few hours tonight based on
current trends and to lower forecast min temps a couple degrees
in the thumb where current temps are already nearing forecast
lows.
PREV DISCUSSION...
Issued at 344 PM EDT Wed SEP 21 2016
DISCUSSION...
Energetic upper levels continue through mid week as a nearly zonal
140+ knot jet streaks across the US/Canada border. Weak southern
stream jet lifting northeast out of the developing west coast upper
level trough, will send a series of shortwaves through the plains
and into northern MI. The pattern has also resulted in a broad
surface developing over the central plains with a warm front taking
shape across the Central Great Lakes. This pattern will deviate very
little now through the end of the week as the strong Hudson Bay low
remains in place.
Area should remain dry through the rest of the evening and into the
overnight hours as subsidence in the wake of the early afternoon MCS
settles over southern MI. Hires HRRR and RAP advertise some
redevelopment this evening along I94 on the sinking outflow boundary
but confidence is low in the occuring. The current cap will make it
hard for anything to develop, even with a bit of late afternoon
heating. Radar trends through the day have shown the convection
struggling to advance much further west than Chicago away from the
stronger height falls. Without any forcing locally and no shortwaves
to speak of during the evening, think convection will struggle even
with peak heating as skies begin to clear out somewhat.
Tonight through Friday will focus on the warm frontal positioning
and shortwaves/MCSs that will ripple along the front for possible
showers and thunderstorms. Models have shifted north with the
positioning of the surface front which in turn refocuses the
developing isentropic forcing north. A brief shortwave ridge
rounding the base of the Hudson Bay low will allow the jet to arch
northward as well which will steer the approaching shortwaves
further north as well. All this leads to shifting the pops north
which really only leaves the Saginaw Valley and northern Thumb with
a short at precip through Thursday. Will highlight the period from
09-15Z Thursday for the best opportunity as the shortwave lifts
through northern lower aided by nocturnal low level jet and next
surge of theta e. The rest of the afternoon will likely dry out for
everyone again but with the front just to the north will leave a
slight chance for the extreme north.
The front will start to sag southward into mid MI Thursday night as
a strong trough rotates around the Hudson Bay low giving it a push.
It should passing through southeast MI by Friday afternoon which
will be the next chance for showers and thunderstorms. Should see a
good thermal gradient across southern MI on Friday with the front
draped across the region. This will mark the end of the current
stretch of 80 degree days as highs north of I69 will struggle to
reach 70 with strengthening northeast flow off Lake Huron. Timing of
the front will decide just how warm the Metro Detroit area can get
before cooling back off.
High pressure over Ontario will keep surface flow with an easterly
component locally over the weekend. Sharp NW/SE low-mid level theta-E
boundary across SE MI, and cannot totally rule out some light
showers Saturday with weak positive theta-E advection and PWAT
around 1.5 inches, but at this point expect most of the weekend to be
dry. Low predictability early next week with guidance indicating a
cutoff low taking shape somewhere to our west over the Northern
Plains/Upper Midwest, with meridionally-oriented moisture plume
ahead of it. Eastward progression of these features will determine
rain chances early next week, and not a whole lot of model consensus
at this point, so chance PoPs early next week will suffice for now.
Despite rather warm mid-level temps, easterly surface flow is
expected to keep temps in check near or slightly above normal.
MARINE...
A front will remain stalled over the northern Great Lakes tonight
through Thursday. An active pattern of showers and thunderstorms
will be the primary marine weather impact, mainly over northern Lake
Huron, while wind and waves remains light/low over other marine
areas. That will change Thursday night and Friday as the front
settles southward into Ohio and opens moderate northeast flow over
all areas. The long fetch of onshore, unstable flow over southern
Lake Huron and into Saginaw Bay will likely produce waves exceeding
SCA levels through Friday night before high pressure settles in
Saturday.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....SC
UPDATE.......SC
DISCUSSION...DRK/DT
MARINE.......BT
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Goodland KS
532 PM MDT WED SEP 21 2016
.UPDATE...
Issued at 527 PM MDT Wed Sep 21 2016
Added areas of fog and low clouds for northwest half of the area
after midnight and into Thursday morning. HRRR suggests both will
develop as cold front sags southward overnight and post frontal
low level upslope develops.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 1210 PM MDT Wed Sep 21 2016
Midday analysis of satellite and radar indicate only partial
clearing for the western half of the CWA with very light isolated showers
in the eastern portions of the area. High resolution data does not
develop much in the way of precipitation through the afternoon
hours with only isolated slgt chc to chc showers expected through
the afternoon and into the evening. Should start to see some
isolated activity in the east and southeastern portions of the CWA
with areas west and northwest remaining dry.
Temperatures have been steadily rising through the morning and we
remain on track to reach our afternoon high in the lower 90s. Lows
tonight should fall into the middle 50s to middle 60s but this
will be cloud cover dependent as the temperatures will be slower
to respond in areas with persistent cloud cover.
Another warmer than average day is in store tomorrow with high
pressure positioned just far enough west to continue the influence
on our temperatures. Subsidence on the western fringe of the ridge
combined with relatively dry air at the surface will keep
precipitation out of the forecast through Thursday afternoon.
Highs should once more reach the lower 90s.
.LONG TERM...(Thursday night through Wednesday)
Issued at 224 PM MDT Wed Sep 21 2016
For the extended period...the main wx concern will focus on a strong
upper low/trough which currently sits off the Pacific coast. This
system will move northeast thru Rockies slowly Thursday night on
thru the upcoming weekend...and eventually set up over the
Northern Plains region before becoming a cutoff/meandering upper
system by next Monday into the middle of next week.
The first chance for precipitation during the extended occurs as a
weak warm front lifts thru the region thursday night...followed by
a cold front for the overnight period into Friday. These occur
out ahead of the upper trough as it lifts thru the Rockies.
Enough instability ahead of the front will warrant mention from
SPC of a Marginal risk for some isolated t-storms w/ the main
focus along the KS/CO border.
The latter half of the extended period will focus on the WNW
circulation over the area. The combination of the upper low over
the Northern Plains and surface high pressure over the NC Rockies
will keep breezy conditions in place. Overall...increased cloud
cover thru the period possible with a few weak shortwaves rounding
the low circulation to help enhance.
For temps...above normal numbers expected before the passage of
the cold front...then the increased WNW surface flow will usher in
a cooler airmass with temps at or just below normal. Looking for
highs to range in the 78-88 range to start...tapering down to
mainly the mid to upper 60s for the remainder. Overnight lows
taper down from near 60F to mainly the 40s by next Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 527 PM MDT Wed Sep 21 2016
Main aviation concern will be the possibility of low clouds and
reduced visibility in fog overnight and into Thursday morning. A
cold front will sag southward tonight and both are expected to
develop in the post frontal low level upslope environment.
Conditions will gradually improve through Thursday morning.
&&
.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...024
SHORT TERM...TL
LONG TERM...JN
AVIATION...024
Area Forecast Discussion
National Weather Service Green Bay WI
1040 PM CDT WED SEP 21 2016
Updated aviation portion for 06Z TAF issuance
.UPDATE...
Issued at 1037 PM CDT Wed Sep 21 2016
Considered trimming back the northern and eastern portion of the
Flash flood Watch this evening with current radar trends. After a
period of heavy convection over parts of Central Wisconsin early
this evening, precipitation has shifted to a stratiform type of
rain over much of the area including northern wisconsin. Radar
rainfall rates were much higher across the north compared to
ground truth. Recent nam has shifted rain to the north
tonight, so was reluctant to pull any headline at this time. In
addition convection was developing upstream over East Central
Minnesota and will be working into the state overnight and PWATS
were forecast to increase. Will let the overnight crew adjust
headlines with the next suite of data. Will likely cancel flash
flood warnings for now but head to areal due rising rivers.
&&
.SHORT TERM...Tonight and Thursday
Issued at 226 PM CDT Wed Sep 21 2016
The latest RAP analysis and satellite/radar imagery show a surface
warm front snaking from southern Minnesota to northern Illinois
early this afternoon. Showers and thunderstorms continue to fire
along the boundary over the same areas that received heavy rainfall
last nite, namely southeast Minnesota and southern Wisconsin.
Additional storms are firing over western Wisconsin in a region of
low level moisture convergence. These storms will likely continue
to develop and push into the I-39/route 51 corridor later this
afternoon. An isolated severe storm will be possible from Lincoln
to Waushara counties with mu capes above 1000 j/kg and 0-6 km shear
of 45-50 kts. As a weak shortwave lifts across the Plains and into
the western Great Lakes tonight, thunderstorm trends and potential
for heavy rain/severe weather are the main forecast concerns.
Tonight...An active period of weather, with an atmosphere conducive
for heavy rainfall. A weak shortwave, currently over southwest
Nebraska will lift northeast and across the region late tonight.
Ahead of the shortwave, a strengthening 30-40 kt low level jet is
anticipated to ride over the slowly northward advancing warm front
later this afternoon into this evening. With ample instability and
shear as shown on mesoanalysis imagery, showers and thunderstorms
are expected to develop and expand upstream of the current
thunderstorm activity over southern and central Minnesota, before
sliding east through the night. Elevated capes of 1000-1500 j/kg
suggest a severe storm cannot be ruled out through the evening,
especially over areas from west of the Fox Valley and south of route
29. In addition, long duration of forcing combined with plentiful
moisture (pwats of 1.75 to 2.00) continues to imply that a flood or
flash flood threat is possible. The latest guidance shows that
central WI from Lincoln to Waushara counties have the most risk for
receiving heavy rainfall, with amounts of 1-3 inches possible
(locally higher). Though concerns are not as high for flooding
further east within the flood watch, potential for heavy rain will
remain, especially over the southern Fox Valley where rainfall over
an inch has already fallen early this morning. Temps ranging from
the mid 50s north to mid 60s south.
Thursday...Model guidance continues to show that the front will
remain stalled over central and northeast Wisconsin. Though weak
shortwave impulses will be passing to the east during the morning,
periods of showers and storms will likely continue through the day.
Weaker forcing and instability suggests rainfall only has a limited
potential to be on the heavy side, so thinking additional amounts of
a quarter to a half inch will be possible, locally higher in storms.
With the rainfall and clouds, temps will remain cooler in the mid
60s to mid 70s.
.LONG TERM...Thursday Night Through Wednesday
Issued at 226 PM CDT Wed Sep 21 2016
A frontal boundary that was just to the southwest of Wisconsin
early this afternoon is the main concern through the end of the
week before a surface low pressure system brings a cold front into
the state.
The approaching warm front will keep at least a chance for
showers and thunderstorms in the forecast through Saturday
morning. Central and east central Wisconsin will be the main
concern for heavy rainfall since the front is expected to be in
that general area before it finally makes a stronger push to the
northeast and clears the state late in the week. Looks like there
could be a period of dry weather, with not even a slight chance
POP, Saturday afternoon but confidence in timing is low.
Have shower and thunderstorm chances returning with the approach
of a cold front from the west, which may take a while to clear the
state. The 12Z GFS, ECMWF and Canadian all started to exhibit
significant differences for early next week but all looked quite
wet through the end of the forecast period.
Highs during the day should be within a couple of degrees of
normal, and lows should be warmer than normal due to all of the
clouds and rain.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1040 PM CDT Wed Sep 21 2016
A nearly stationary frontal boundary extending from west to east
over the state will be a focus of showers and storms tonight into
Thursday. Cigs and vsbys will continue to deteriorate tonight and
continue into Thursday. Slightly drier air across parts of
northeast Wisconsin were keeping vfr conditions lingering late
this Wednesday evening.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Thursday evening FOR WIZ018>020-030-
031-035>040-045-048>050.
&&
$$
UPDATE.........TDH
SHORT TERM.....MPC
LONG TERM......MG
AVIATION.......TDH
Area Forecast Discussion
National Weather Service Wilmington NC
1125 PM EDT Wed Sep 21 2016
.SYNOPSIS...
The remnant circulation of former Tropical Storm Julia will maintain
scattered showers through Friday. Drier weather should develop
Saturday as high pressure pokes in from the north. A cold front will
move through early Sunday, followed by several days of onshore winds
and slightly cooler temperatures next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 1030 PM Wednesday...Have upped POPs to likely as convection
over the adjacent Atl waters has already begun its development and
its push inland. Already, a few cells have pushed onshore. One of
them went directly over ILM ASOS, and deposited 0.85 inches of
rainfall in 30 minutes. With PWS at or higher than 2.00 inches,
this pcpn activity will be quite zealous in its production of QPF
amounts. Have updated the QPF with hier amounts for the overnight
period.
No lightning strikes with this activity at the moment. Will
continue to mention isolated thunder...and the heavy rain
phraseology. Have upped mins, hourly temps and dewpts by 1 to 3
degrees across the ILM CWA due to the clouds and pcpn.
Previous.....................................................
As of 815 PM Wednesday...Main feature, the upper low, initially
will be directly overhead this evening. During the overnight,
models are in a general agreement in the upper low meandering
slightly to the southwest. This will result instead of a
northerly component to the winds aloft early this evening, winds
aloft will become more SE to S oriented due to the
counterclockwise rotation around this upper low. Thus instead of
wraparound moisture, will be dealing with direct moisture from off
the Atlantic. PWs will increase to over 2.00 inches across the
majority of the ILM CWA, except the far NW portions will it remain
below. This via latest GFSbufr soundings. The onshore movement of
pcpn will pick later tonight, mainly during the pre-dawn THU hours
thru the late morning daytime Thu hrs. This to reflect the
nocturnal Atlantic engine revving up an area of showers and
tstorms followed by the onshore movement then redirected toward
the wsw-sw, associated with the upper low`s circulation. The pcpn
over the north and west of the I-95 corridor will be far lighter
with no deep convection. Again, the deeper convection and threat
for thunder will remain closer to the coast. With high PWs, the
rainfall accompanying the stronger activity will be highlighted
with heavy rain phraseology. This already occurring over a 10-20
mile wide band of convection extending from Burgaw, across Bolton
and Tabor City to Pamplico. Other concern will be another night of
widespread low stratus, which seems feasible except along the
immediate coast where pcpn will be moving onshore. Current min
temp fcst looking aok.$$ AMZ250-220745- COASTAL WATERS FROM
SURF CITY TO CAPE FEAR NC OUT 20 NM- 827 PM EDT WED SEP 21 2016
.OVERNIGHT...E WINDS 10 KT. SEAS 2 TO 3 FT. A CHANCE OF SHOWERS WITH
ISOLATED TSTMS. .THU...NE WINDS 10 KT. SEAS 3 FT. SHOWERS LIKELY
WITH ISOLATED TSTMS. .THU NIGHT...E WINDS 10 KT OR LESS. SEAS 3 TO
4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI...NE WINDS 10 KT
OR LESS...INCREASING TO 10 KT IN THE AFTERNOON. SEAS 3 TO 4 FT. A
CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI NIGHT...NE WINDS 10 KT.
SEAS 3 FT. A SLIGHT CHANCE OF SHOWERS WITH ISOLATED TSTMS.
.SAT...NE WINDS 10 KT. SEAS 3 TO 4 FT. .SAT NIGHT...E WINDS 10 KT.
SEAS 3 FT. .SUN...E WINDS 10 KT. SEAS 3 TO 4 FT. .MON...E WINDS
10 TO 15 KT. SEAS 3 FT. WINDS AND SEAS HIGHER IN AND NEAR TSTMS.
$$ AMZ252-220745- COASTAL WATERS FROM CAPE FEAR NC TO LITTLE RIVER
INLET SC OUT 20 NM- 827 PM EDT WED SEP 21 2016 .OVERNIGHT...E WINDS
10 KT. SEAS AROUND 2 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS.
.THU...NE WINDS 10 KT. SEAS 2 TO 3 FT. SHOWERS LIKELY WITH ISOLATED
TSTMS. .THU NIGHT...SE WINDS 10 KT OR LESS. SEAS 2 TO 4 FT. A
CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI...E WINDS 10 KT OR LESS.
SEAS 2 TO 4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI
NIGHT...NE WINDS 10 KT. SEAS 2 TO 3 FT. A CHANCE OF SHOWERS WITH
ISOLATED TSTMS. .SAT...NE WINDS 10 KT. SEAS 2 TO 4 FT. .SAT
NIGHT...E WINDS 10 KT. SEAS 2 TO 4 FT. .SUN...E WINDS 10 KT. SEAS
2 TO 4 FT. A CHANCE OF SHOWERS AND TSTMS THROUGH THE NIGHT.
.MON...E WINDS 10 TO 15 KT. SEAS 2 TO 4 FT. A CHANCE OF SHOWERS AND
TSTMS THROUGH THE NIGHT. WINDS AND SEAS HIGHER IN AND NEAR TSTMS.
$$ AMZ254-220745- COASTAL WATERS FROM LITTLE RIVER INLET TO
MURRELLS INLET SC OUT 20 NM- 827 PM EDT WED SEP 21 2016
.OVERNIGHT...E WINDS 10 KT OR LESS. SEAS 2 FT. A CHANCE OF SHOWERS
WITH ISOLATED TSTMS. .THU...NE WINDS 10 KT. SEAS 2 TO 3 FT. SHOWERS
LIKELY WITH ISOLATED TSTMS. .THU NIGHT...E WINDS 10 KT OR LESS.
SEAS 2 TO 4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI...E
WINDS 10 KT OR LESS. SEAS 2 TO 4 FT. A CHANCE OF SHOWERS WITH
ISOLATED TSTMS. .FRI NIGHT...NE WINDS 10 KT. SEAS 2 FT. A SLIGHT
CHANCE OF SHOWERS WITH ISOLATED TSTMS. .SAT...NE WINDS 10 KT. SEAS
2 TO 3 FT. .SAT NIGHT...E WINDS 10 KT. SEAS 2 FT. .SUN...E WINDS
10 KT. SEAS 2 TO 3 FT...BUILDING TO 2 TO 4 FT. A CHANCE OF SHOWERS
AND TSTMS THROUGH THE NIGHT. .MON...E WINDS 10 TO 15 KT. SEAS 2 TO
3 FT. A CHANCE OF SHOWERS AND TSTMS. WINDS AND SEAS HIGHER IN AND
NEAR TSTMS. $$ AMZ256-220745- COASTAL WATERS FROM MURRELLS INLET
TO SOUTH SANTEE RIVER SC OUT 20 NM- 827 PM EDT WED SEP 21 2016
.OVERNIGHT...E WINDS 10 KT OR LESS...INCREASING TO 10 KT. SEAS 2 FT.
A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .THU...NE WINDS 10 KT.
SEAS 2 TO 3 FT. SHOWERS LIKELY WITH ISOLATED TSTMS. .THU NIGHT...E
WINDS 10 KT OR LESS. SEAS 3 FT. SHOWERS LIKELY WITH ISOLATED TSTMS.
.FRI...E WINDS 10 KT OR LESS. SEAS 3 FT. A CHANCE OF SHOWERS WITH
ISOLATED TSTMS. .FRI NIGHT...NE WINDS 10 KT OR LESS. SEAS 3 FT. A
SLIGHT CHANCE OF SHOWERS WITH ISOLATED TSTMS. .SAT...NE WINDS 10 KT.
SEAS 3 FT. .SAT NIGHT...E WINDS 10 KT. SEAS 3 FT...SUBSIDING TO
2 FT AFTER MIDNIGHT. .SUN...E WINDS 10 KT. SEAS 2 TO
3 FT...BUILDING TO 3 TO 4 FT. A CHANCE OF SHOWERS AND TSTMS THROUGH
THE NIGHT. .MON...E WINDS 10 TO 15 KT. SEAS 3 FT. A CHANCE OF
SHOWERS AND TSTMS. WINDS AND SEAS HIGHER IN AND NEAR TSTMS. $$
DCH
Previous........................................................
As of 300 PM Wednesday...Low pressure over southeast NC will
drift slowly SW becoming more elongated along the SC coast by this
evening with a trough extending northward from center of low. An
easterly on shore flow will exist on the front end of low/east
side of trough along the coast and continued NE-N flow inland, on
back end of low/west side of trough. This pseudo warm front/trough
will provide a warmer easterly flow and will allow for some
drying and thinning of the clouds. At the same time energy will
continue to rotate around this upper low combining with deeper
layer moisture inland to produce showers and isolated
thunderstorms wrapping around to the S-SE into Northeast SC. Pcp
water values show a plume of deeper layer moisture with values
over 2 inches running from VA/NC coast around to the SW to S
through central NC/SC. Coastal NC will have some drier air
wrapping around from the S to SE with pcp water values down closer
to 1.7 inches this aftn. Overall, instability will remain marginal
due in part to significant cloud cover, so although clouds will
blanket most of the area, expect modest QPF amounts of most areas
with greatest amounts aligned inland mainly just west of I-95
corridor. If areas break out along the coast, expect some heating
and differential heating to produce some further convective
development mainly across central portions of forecast area inland
from the coast.
As this deep low drifts S-SW toward the GA/SC coast through
tonight, some deeper layer moisture will wrap back around over
the Cape Fear region and should increase shwr activity over the
eastern portions of the forecast area overnight as moisture and
showers spread from the coastal waters along the coast in a
deeper E-SE flow. Expect mainly light to moderate rain but some
embedded heavier rain amounts are possible. Overall the cool pool
aloft and continued moist flow will produce plenty of clouds and
potential for pcp through tonight.
Temperatures inland in northerly flow on back side of low will
remain in the mid 70s this aftn while temps along the coast will
reach over 80 especially where some breaks or thinning in the
clouds occurs.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...The persistent mid to upper low will
become more elongated and may drift westward before opening up
into a trough along the east coast and moving off shore by Fri
night. The center of the low will remain south of the area with
trough extending northward maintaining a deeper on shore flow
through the period. The trough looks like it will be just along or
off shore which will keep a N-NE flow over much of the area but
should see more of an E-SE flow at times along the coast and off
shore as trough and diurnal shifts take place. Pcp water values
will remain up above 1.75 inches through much of the period in a
very moist air mass. With such deep layer moisture and a deep
low/trough over the region through the period, expect unsettled
weather to continue. While POP areal coverage should remain
scattered most of this period, there will be bands of showers with
more moderate to heavy rain across portions of the area associated
with upper level energy rotating around over the region.
Drying will finally take place late Fri into early Saturday as
trough finally moves off to the east. Skies will begin to clear
from west to east leaving partly cloudy skies by Fri night over
most places. Max temps will reach near or around 80 during the
afternoons overnight lows near 70 Thurs night but slightly lower
Fri night as some clearing occurs.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 300 PM Wednesday...The upper levels will certainly not look
anything like summer with a very amplified trough-ridge-trough
pattern expected to develop across North America. Models have
struggled to form a consensus over the past few days with details,
however the new 12z GFS may be on to something with its depiction of
an Omega block developing by Tuesday. Due to this blocked pattern,
the potential of a strong cold frontal passage late this month is now
in jeopardy and we may remain in the tropical/subtropical humidity
through the remainder of September.
A 500 mb ridge centered across the Mississippi Valley on Saturday
will only slowly work east into the Carolinas by Tuesday and Wednesday.
A deep upper level low moving across the Canadian Maritime provinces
will push a cold front southward along the East Coast, reaching the
Carolinas early Sunday. The surface high behind this front won`t dive
south, and in fact may only reach coastal New England by late Tuesday
or Wednesday. This will create an extended period of onshore winds
and the potential for scattered showers as a band of convergence
behind the old front could settle across the area, coincident with at
least shallow Atlantic moisture.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
As of 00Z...A low level convergence boundary will affect LBT and FLO
through about 01Z, with most of the convection dissipating after
that. Overnight, fairly high confidence for IFR conditions at all
locations with abundant low level moisture. Surface low pressure
will have convection on the increase toward morning at ILM, well
depicted by the HRRR model. This precip will likely continue through
early afternoon, spreading inland after that. Light mainly northeast
flow through midday on Thursday.
EXTENDED OUTLOOK...Isolated to scattered afternoon
and early evening convection possible underneath the cutoff upper
low through Friday. MVFR/IFR morning stratus/fog possible each day
through Sunday.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1030 PM Wednesday...This update concerned with PCPN
coverage. Have upped the shra and isolated thunder coverage
overnight based on latest 88D trends and near term Model guidance
ie. HRRR and the RAP.
Previous.....................................................
As of 830 PM Wednesday...Have increased the coverage and POPs
associated with the development of convection over the Atlantic
waters during the pre-dawn Thu hours thru mid to late daytime
morning Thursday. The cloud to ocean lightning strikes will be
limited, however the main concern will be the reduced VSBY, less
than 1 nm at times, caused by the heavy rainfall. Current wind
fcst will mainly be from an easterly direction, with a relaxed sfc
pg, speeds will be around 10 kt. Significant seas will run 2 to
around 3 ft. This depends on how much of an influence the T.S.
Karl fore-runners have on the local waters. At this point,
wavewatch3 and local Swan models, both indicate a 1.5 to 2.5 foot
ese hurricane swell at 10-12 second periods. This will become the
dominating feature to the significant seas spectrum by daybreak
Thu.
Previous.......................................................
As of 300 PM Wednesday...A deep low over the Cape Fear region
will drift southwest through tonight. This will result in a weak
pressure gradient with winds 10 knots or less through the day.
Wind direction will also be somewhat variable, but in general, an
onshore flow will continue as the low center drifts southwest. It
should kick back to a more northeasterly direction close the coast
on the back end of the low and more E-SE farther off shore on the
front end of low. Mid- level dry air over the waters is expected
to limit storm development today, but should increase overnight in
deeper on shore flow. Seas will remain less than 3 ft mixing in
with some longer period SE swells arriving tonight.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...Low pressure will weaken south of the
waters with trough aligned up the coast through the period.
This will keep an on shore flow through the period and depending
on the exact position of the trough, the winds will fluctuate
between E-SE to E-NE over the waters...remaining 10 kts or less.
Winds will turn more northerly and pick up a bit by Fri night as
low finally moves off to the east. Showers and isolated TSTMS
will remain in the mix. Seas will basically remain 3 ft or less
with a slight, slow and steady rise as a longer period up to 12
second SE swells mix in.
LONG TERM /SATURDAY THROUGH MONDAY/...
As of 300 PM Wednesday...Julia`s remnants should be long gone from
the weather map by Saturday. High pressure dropping southward from
the southern portion of Hudson Bay will push a cold front through the
Carolinas early Sunday. This front will sink to coastal Georgia
Monday with easterly winds developing across the Carolinas. Scattered
showers should develop mainly behind the front beginning Sunday
night.
Wave heights of 2-3 feet are expected south of Cape Fear Saturday
into the first half of Sunday, with the potential for 3-4 foot seas
near and north of Cape Fear due to residual swells emanating from
distant Tropical Storm Karl. By Sunday night modest onshore winds
will create the potential of shorter period 2-4 foot waves away
throughout the area, continuing into Monday.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...TRA
NEAR TERM...DCH/RGZ
SHORT TERM...RGZ
LONG TERM...TRA
AVIATION...DL
MARINE...
Area Forecast Discussion
National Weather Service Northern Indiana
751 PM EDT Wed Sep 21 2016
.SYNOPSIS...
Issued at 326 AM EDT Wed Sep 21 2016
High pressure will continue to provide fair weather as it remains
stationary across the area through Thursday night. Lows tonight
and Thursday night will be in the lower to middle 60s, with highs
Thursday and in the mid 80s. A weak cold front will move across
the area Friday, bringing a slight chance of thunderstorms
northeast of a South Bend to Defiance line. Slightly cooler air
will follow the front into the area over the weekend. A slow
moving low pressure system is expected to move into the area early
next week bringing our next chance of rain.
&&
.SHORT TERM...(This Evening through Thursday)
Issued at 324 PM EDT Wed Sep 21 2016
So far upstream convection has behaved as advertised and continues
to weaken as it moves east out of deeper instability and away from
stronger synoptic forcing. HRRR still wants to occasionally develop
an isolated cell in our north through 00z with modest instability
and decent mid level lapse rates. So far outflow boundaries have not
been strong enough to force any development. Vis sat loop does show
some cu trying to develop over the northwest in vicinity of where
HRRR has tried to convect. Also watching remnant convection sliding
southeast from northern Illinois. Will carry the slight chance pops
over the north and northwest through 00z followed by dry conditions
for the overnight period as main front lifts north. This boundary now
looks to reside far enough north on Thursday that pcpn chances will
be 10 percent or less and upstream convective complex tonight over
WI to stay north of our area tomorrow. Should still see some cloud
debris but expect more sun than today and temps will once again
recover nicely well into the 80s. ECE MOS kicking out upper 80s over
parts of the region but will hold shy of this in the mid 80s with
the potential for the debris clouds at times.
&&
.LONG TERM...(Thursday Night through Wednesday)
Issued at 324 PM EDT Wed Sep 21 2016
Upper level pattern to transition from zonal to a meridional flow
through the period. This will complicate forecast by early next
week with various model solutions revolving around cut off upper
low and an occluded front.
Backdoor front will begin to slide into the area later Friday and
Friday night. Moisture limited and not much synoptic forcing. Slight
chance pops continue in the northeast. This boundary will bring
northeast winds and cooler temps through the weekend but still above
normal for late September. Highs in the middle to upper 70s still
expected.
More uncertainty exists with potential frontal boundary early next
week. GFS and ECMWF continue to have differences with respect to a
cut off upper low over the central CONUS and how an occluded front
associated with it will translate east. GFS continues to be faster
model while ECMWF remains slower. These differences being dictated
by large trough off the northeast CONUS and stout ridge between that
trough and the developing upper low over northern Plains. GFS wants
to push sfc boundary through the ridge while ECMWF stalls this
boundary to our west. For now will be using the Superblend init
until more certainty develops. Preference is toward ECMWF as GFS has
a bias of breaking down ridges and seems to be doing that here as
well. Temps remain mild in the 70s but should trend closer to normal
next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 733 PM EDT Wed Sep 21 2016
Sfc ridge extending from the ne U.S. across IN will persist through
the period resulting in dry conditions. TS will continue to develop
along a stnry front across WI/MN/IA and propagate sewd but dissipate
or turn more s-sw toward unstable airmass over the MS valley with
just some mid-high clouds advancing across our area. Given
stagnant airmass over the area, a repeat of mvfr vsbys in br
around dawn likely again in the Maumee valley including fwa Thu
morning.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...jt
SHORT TERM...Lashley
LONG TERM...Lashley
AVIATION...JT
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Area Forecast Discussion
National Weather Service Medford OR
857 PM PDT WED SEP 21 2016
Updated to include information about snow in the Cascades.
.SHORT TERM...The upper level low over the area has brought isolated
thunderstorms and scattered showers this evening across inland
areas including Douglas, Josephine, Jackson, Siskiyou and Klamath
Counties. The chance for thunderstorms will continue late this
evening but expect storms to remain isolated. Also the best area
for storm development will be over central and eastern Siskiyou,
Klamath and western Lake counties. These storms have mainly
brought light to moderate rain with occasional lightning.
After midnight, models continue to show that thunderstorm chances
will diminish but showers will continue for as the low remains in
place over the area. The best chances for showers will be from the
from the I-5 corridor eastward. The high resolution HRRR also
shows some isolated showers along the coast from around Cape
Blanco southward tonight. So have added a slight chance for showers
to these coastal areas. Of note, models are highlighting the around
0.1 to 0.2 inches of precipitation in the Cascades overnight into
early Thursday morning. With the cold air mass moving into the area
and snow levels lowering to around 6000 feet elevation, expect
these showers to bring 1 to 3 inches of snow to the higher portions
of the Southern Oregon Cascades. Snow is expected to melt fairly
quickly though due to warm ground temperatures.
Otherwise, the forecast remains on track for Thursday with continued
showers expected for inland areas Thursday morning and then the
focus of showers will shift more from the Cascades east in the
afternoon. A slight risk for thunderstorms is also expected in
east side areas, mainly over Modoc and Lake Counties Thursday
afternoon. As the low moves east of the area Thursday evening,
expect diminishing showers. Behind the low, a cold air mass will
be in place across the east side Thursday night and Friday
morning, with low temperatures expected near or below freezing for
valleys east of the Cascades.
&&
.AVIATION...21/18Z TAF CYCLE...The main concern through this evening
will be gusty winds which could cause some turbulence east of the
Cascades especially near thunderstorms where winds could become
gusty and erratic. There is a slight chance for thunderstorms in
the Cascades, Siskiyous and across Siskiyou and Klamath counties
late this afternoon and evening. Any storms will end this evening,
but showers will persist mainly east of the Cascades. Tonight into
tomorrow morning, a good portion of the forecast area will likely
become MVFR with increasing moisture in the region. Most areas
should clear to VFR by late tomorrow morning, with gusty winds
expected east of the Cascades. -BPN/SK
&&
.MARINE...Updated 840 PM PDT Wednesday 21 September 2016...A weak
front will move through Friday afternoon...bringing increasing south
winds and choppy seas. Long period westerly swell will arrive
Friday night into Saturday. A thermal trough will develop Saturday
into Sunday...bringing strong north winds and steep seas. The
trough will weaken Monday. Winds will diminish and seas will subside
at that time.
&&
.PREV DISCUSSION... /Issued 334 PM PDT WED SEP 21 2016/
DISCUSSION...Cooler, breezy, and occasionally wet weather is in
store through Friday. A cold upper level trough has reached the
coast and will move across the area tonight. Instability will
increase this evening and will result in at least a slight chance
of showers for most of the area through tonight. These will be
mainly over the higher terrain...especially over the Siskiyou and
Cascade mountains and Cascade foothills. There is also the
possibility of a few embedded thunderstorms through this evening.
The highest probability of showers along the I-5 corridor will be
shortly after midnight into early Thursday morning with the aid
of an embedded shortwave.
On Thursday, the risk of showers and thunderstorms will shift east
with a focus from the Cascades across the east side. Precipitation
amounts during tonight and tomorrow will mainly be light with
amounts of less than 0.05 inches. But, given the showery nature,
some areas in the Cascades may receive around a half an inch. Snow
levels will drop from around 7500 feet to around 6000 feet with up
to an inch of snow expected.
Showers are expected to taper off over the Cascades and east side
during Thursday evening with a lingering slight chance of
thunderstorms over the Warner Mountains of Lake and Modoc
Counties.
A break between systems on Thursday night will be short. Clouds
are expected increase from the west late Thursday night as a
weakening warm front approaches. Despite the trend of its
strength, it will still be moderately strong as moves into the
coastal waters then likely brings rain to the coast during Friday
morning. There is a high probability of light west side rain from
Friday morning through Friday evening with a chance of rain along
the I-5 corridor by early afternoon. Little, if any precipitation
will reach the east side during Friday night.
A strong high pressure ridge is still indicated to build from the
eastern Pacific into our area during the weekend into Monday. This
will bring a drastic warming and drying trend with inland high
temperatures on Sunday expected to 15 to 30 degrees higher than on
Friday.
Beyond Monday, model agreement diminishes. There is high
uncertainty regarding the strength and timing of a trough that
will move out of the Gulf of Alaska toward the Pacific Northwest.
The GFS is notably faster and likely too fast with the arrival of
this trough. Moisture with the trough is likely to remain mostly
and perhaps exclusively north of our area. An associated weak
front would likely lead to at least slight cooling toward mid-week
and could produce an episode of stronger than typical east side
winds.
FIRE WEATHER...Updated 100 PM Wednesday 21 September 2016...An
upper low is swinging eastward into the forecast area this
afternoon. Ahead of this trough, gusty southwest to west winds are
expected this afternoon over much of the East Side. Also, a dry
slot is being observed on the water vapor imagery pushing over
areas east of the Cascades, and this will bring lower humidities
to that area this afternoon. Due to these factors, a Red Flag
Warning continues for portions of Modoc County this afternoon
through early evening.
In addition to the gusty winds and low RH, showers and thunderstorms
will bring some wetting rains to the forecast area this afternoon
through Thursday. We are highly confident that the Cascades north of
Highway 140 will receive wetting rains. Several models suggest at
least 0.5 inches of rain will fall there this afternoon through
Thursday. Additionally, the high terrain of the Fremont NF will
likely see wetting rains. Outside of those areas, less than a
quarter inch of rain is expected, with the lowest amounts at the
coast and in the lowest elevation valleys. The upper low is
progressing steadily to the east, and moisture is not impressively
deep, so widespread wetting rains across the forecast area are not
expected.
Thunderstorms are expected in some places today, mainly over higher
terrain. Rain will accompany these storms today into tomorrow.
Additionally, the air mass is cooling as the upper low moves inland,
and snow levels will drop to near 6000 feet by Thursday morning.
There will be ongoing showers at this time, so some areas will
likely see some snowfall. Crews on fires such as the Soup Complex
will experience some cold and potentially wet/snowy weather Thursday
morning.
Warm frontal precipitation will brush the areas along and west of
the Cascades with light precipitation on Friday. The consensus of
models suggests the potential for wetting rains again in the
Cascades north of Crater Lake, while other areas will likely see
less than a tenth of an inch of rainfall.
Warm and dry conditions will follow the cool and moist pattern from
Saturday through early next week at least.
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.
CA...None.
Pacific Coastal Waters...None.
$$
CC/CC/CC
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1047 PM CDT WED SEP 21 2016
.SHORT TERM...(This evening through Thursday)
Issued at 326 PM CDT Wed Sep 21 2016
The next 12 hours will feature widespread showers and
thunderstorms across a large portion of Minnesota and western
Wisconsin. While a few straight-line wind gusts and a weak tornado
are not impossible, the two greater threats this evening are
heavy rain with the potential for flash flooding and hail between
1-2" in diameter.
You don`t have to be a meteorology major to find the main warm
front this afternoon in Minnesota. North of a line from roughly
Granite Falls, to the southern Twin Cities metro, to Eau Claire
there is overcast skies temperatures in the 60s and northwest
surface winds. South of this line, the winds are southerly and
temperatures are in the 70s and 80s with dewpoints in the 70s. The
instability gradient is stretched out along this line with max
values near 3500-4000 J/kg (SBCAPE and MLCAPE) in far south
central MN and near 0 J/kg in the far northern TC metro. Good
elevated instability and steep mid-level lapse rates extends well
north of the surface boundary. In addition to the building
instability, the 925-850mb moisture transport and warm advection
have increased quite a bit over the past couple hours. The FGEN
in this area has also increased since mid afternoon. The result
has been the expansion of thunder along or north of the boundary.
Storms have been efficient rainfall producers with rain rates
between 2-3". The storms have also been efficient hail producers
as well, not too much of a surprise given the instability in the
hail growth zone, shear profile, and due to the fact that the
surface temperatures are in the 60s along and north of the
boundary. We expect the radar scope to continue to expand in
coverage this evening. The placement of the Flash Flood Watch is
still looking good, although some of the convective allowing
models are developing convection back farther to the southwest.
Though the HRRR has admittedly struggled with the short term
trends. Settle in, its going to be a busy night for weather in
MN/WI over the next 12 hours. There will likely be elevated hail
and heavy rain north of the front that move east northeast, but
there will also likely be a broken line of storms that form along
the boundary and sag south with time.
.LONG TERM...(Thursday night through Wednesday)
Issued at 326 PM CDT Wed Sep 21 2016
Highly amplified flow in the extended will evolve into a cut off low
which is a pattern that has high uncertainty. For that reason and
given the high impact weather expected in the next 24 hours, did not
stray from blended guidance in the extended period. There`s a few
highlights below.
The warm front responsible for the heavy rain will be laid out
somewhere along I-90. Storms should continue to Thursday night. On
Friday the warm front will lift northward and showers and
thunderstorm chances will be tied to the front. There will be warm
and dry conditions in the warm sector, but this will be short-lived
as a cold front moves in Saturday and brings a few showers and
thunderstorms.
Beyond this period, the upper level wave will cut off and bring a
prolonged period of clouds and light rain. As mentioned above, there
is uncertainty in this pattern, so would not be surprised if the
forecast changes. The GFS is a bit quicker with the cutoff low, but
the ECMWF catches up by the middle of next week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1047 PM CDT Wed Sep 21 2016
SCT SHRA/TSRA will continue for much of the night across
eastern/southern MN and western WI. MVFR ceilings will deteriorate
to IFR during the overnight hours and continue Thursday morning
before slowly improving back to MVFR for the afternoon/evening.
Visibilities will be highly variable due to the precipitation. SCT
SHRA/TSRA expected to become dominate again late Thursday
afternoon across southern MN with the activity spreading northward
Thursday night. Mainly ENE winds 6-12 knots through the period.
KMSP...SCT SHRA/TSRA will occur through the first 6 hours of the
TAF along with ceilings deteriorating to IFR. Ceilings will be
slow to improve during the day. SHRA/TSRA chances rise again
Thursday evening.
/OUTLOOK FOR KMSP/
Fri...MVFR/SHRA possible. Wind E 5-15kts.
Sat...VFR with MVFR/TSRA likely. Wind SE at 10g15kts.
Sun...VFR. Wind W-SW 10g20kts.
&&
.MPX Watches/Warnings/Advisories...
WI...Flash Flood Watch through Thursday evening for WIZ024-026-028.
Flash Flood Watch until 7 AM CDT Thursday for WIZ014>016-023-025-
027.
MN...Flash Flood Watch through Thursday evening for MNZ067-069-070-
074>078-082>085-091>093.
Flash Flood Watch until 7 AM CDT Thursday for MNZ051>053-059>063-
066-068.
&&
$$
SHORT TERM...CLF
LONG TERM...JRB
AVIATION...RAH
Area Forecast Discussion
National Weather Service Marquette MI
903 PM EDT WED SEP 21 2016
.UPDATE...
Issued at 902 PM EDT WED SEP 21 2016
Based on radar trends showing a sharp back wrn edge of the area of
showers moving thru nw WI, diminishing ltg trends within the showers
over Upr MI/adjoing nrn WI and more resilient dry air to the n,
lowered fcst pops by accelerated the drying trend fm the nnw as shown
by the latest HRRR model run. The new fcst still retains the
categorical/hier likely pops over the s half or so of the cwa. The
main reason this pcpn area wl not expand farther to the n and thus
diminish faster is the axis of robust convection dvlpg fm scentral MN
into central WI closer to h85 warm fnt/fgen axis/area of pwat aprchg
2 inches/sharper differential dvgc fm h85 thru h3/hier mucape aoa 2k
j/kg is robbing mstr inflow into Upr MI and lowering the chc for
deeper saturation over this area. &&
.SHORT TERM...(This evening through Thursday)
Issued at 358 PM EDT WED SEP 21 2016
Dry air exists over the northern CWA where a SFC ridge extends. A
SFC low over the central plains has an inverted trough extending NE
across WI and lower MI, with an area of convection along the
elevated portion of the warm front over a good portion of WI. Most
do not initialize well with the current convection, and those poorly
initializing models blow convection up across the SW CWA this
evening as the warm front moves north and LLJ ramps up. If the front
can move into the area with the LLJ, heavy rainfall would be a
significant issue this evening and tonight as warm cloud depths
would be over 11kft, PWATs near 1.75" and storm motion slow and
nearly parallel to the front. Several inches of rain would be
possible especially along the WI border. However, models that do
initialize well (or at least better) with the WI convection (HRRR,
HRRR-EXP, Canadian-Regional) keep heaviest precip will south of the
area as the LLJ will be hindered north of that convection and the
front may not even make it into the area. These models do bring
precip into the area, just not the heaviest. Could still see 0.50-
1.00 inches right along the WI border. Thu should see overall
diminishing precip chances, but isolate to scattered showers will
continue to be possible through the day, especially over the south.
The Keweenaw will see the lowest precip chances through tomorrow,
possibly being dry much of the time.
.
.LONG TERM...(Thursday night through Wednesday)
Issued at 445 PM EDT WED SEP 21 2016
An amplified pattern will prevail with a prominent mid/upper level
ridge from the se CONUS through central Canada by this weekend and a
trough slowly moving through the wrn CONUS. Although the models were
in agreement with the development of a cutoff low over the cntrl
CONUS there were large inconsistencies and run to run variations
with the evolution and position of the low. So, uncertainty is
higher than usual for this time frame with low forecast confidence.
Thursday night into Friday, as the mid/upper level ridge builds to
the west, sfc high pres over nrn Ontario will build to the south
with drier air pushing into the nrn Great Lakes. This will push most
of the pcpn south of the cwa. However, there still may be some light
showers south central Thursday evening and far south overnight with
weak bands of fgen to the north of the 850 mb front.
Friday night and Saturday, the models were in better agreement that
a stronger band of 700-500 mb fgen will develop in response to the
amplifying ridge to the west and upper level div with the right
entrance of the 250-300 mb jet to the northeast. This will support
at least chance pops over most of the area by late fri night into
sat morning. There is still some uncertainty with the impact of the
antecedent dry airmass on the progression of the pcpn.
Sunday through Wednesday, the developing blocking pattern will slow
the advance of the pcpn associated with the strong moisture
transport and forcing ahead of the plains trough with the highest
pops mainly from sun night through mon. Even with the higher
uncertainty with the cutoff low, shra chances are expected to linger
through wed with the potential for the low lingering just to the
west, per 12z GFS/GEFS/ECMWF.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 747 PM EDT WED SEP 21 2016
An area of showers will impact mainly IWD and SAW tngt. As the rain
grdly moistens the initially dry llvls, expect VFR conditions this
evng to deteriorate to IFR cigs at IWD and SAW late tngt toward
sunrise. CMX wl remain under the influence of drier llvl air and
very likely see fewer -shra and no worse than MVFR cigs. Not out of
the question a TS could impact IWD this evng, but included no more
than a VCTS group as the probability is not that hi per recent ltg
trends. The arrival of some drier air wl end the showers and result
in a grdl improvement in conditions on Thu.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 358 PM EDT WED SEP 21 2016
NE flow over Lake Superior with SFC trough moving into Upper MI and
SFC ridge over Ontario could support some higher wind gusts to 25
knots over the western half of the lake into Thu and across the
entire lake Thu night into Fri. As the Canadian high builds more
over the Upper Lakes, winds will dip below 20 kts Friday night into
Saturday night. Southerly winds will increase late Sunday into Mon
to 25 to 30 knots over mainly the north central and eastern part of
the lake as a low pressure trough approaches from the west.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
UPDATE...KC
SHORT TERM...Titus
LONG TERM...JLB
AVIATION...KC
MARINE...Titus
Area Forecast Discussion
National Weather Service Spokane WA
825 PM PDT Wed Sep 21 2016
.SYNOPSIS...
Unsettled weather is expected late today through Thursday as a
large area of low pressure slowly moves by the region. Look for
breezy north winds at times. Thursday will be the coolest and
dampest day of the week. Then by Friday and through the weekend,
high pressure will arrive with less wind, warmer and dry weather.
&&
.DISCUSSION...
Update: The forecast has been updated to mainly lower POP`s into
Thursday morning. Overall a bit of a complex weather situation
through Thursday morning and have utilized satellite
trends...latest HRRR runs...and the 18z/00z model guidance. Large
closed low near Medford, Oregon this evening with a plume of
moisture being drawn north ahead of it across extreme SE
Washington, Idaho Panhandle, and western Montana. The latest model
guidance keeps the deep moisture generally east of the area,
clipping the Camas Prairie and Idaho Panhandle. A wave that is
riding this moisture plume has generated scattered showers and
even a few thunderstorms this evening near the Rathdrum and
Bayview areas. This wave will continue to move north with
increasing showers over the North Idaho Panhandle this evening.
Water vapor shows drier air moving in behind this wave with
satellite showing a large area of clearing from Colville to
Davenport through the Upper Columbia Basin. The Cascades,
Wenatchee area, and Okanogan Valley are staying west of this dry
air and will continue to see isolated showers this evening.
Overnight into Thursday morning another wave coming around the low
moves north out of Oregon into SE Washington giving the Pullman
and Lewiston areas as well as locations south of our area (Tri
Cities) the best chance for rain showers. Further north latest
models suggest more hit and miss showers and thus have lowered
POP`s for much of North Central and NE Washington Thursday morning
to chance instead of likely. JW
&&
.AVIATION...
00Z TAFS: Scattered showers are expected this evening with rain
showers likely for SE Washington and the Lewiston area Thursday
morning. CIG`s are expected to lower, but confidence on the
precise amount is low due to model differences with intensity and
coverage of rain and consequent moistening of the boundary layer.
Most TAF sites are expected to remain VFR...with a chance of MVFR
conditions for KPUW 13z-19z. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 48 61 46 64 44 67 / 30 50 20 10 10 0
Coeur d`Alene 49 61 48 64 44 65 / 40 50 20 10 10 10
Pullman 47 56 44 62 42 65 / 40 60 30 10 10 10
Lewiston 52 62 51 69 50 70 / 50 60 40 10 10 10
Colville 45 64 42 69 40 70 / 40 50 10 10 10 0
Sandpoint 47 60 41 63 39 64 / 40 50 20 10 10 10
Kellogg 45 58 43 59 41 61 / 50 50 30 10 20 10
Moses Lake 49 67 43 70 43 72 / 20 30 10 10 10 0
Wenatchee 50 66 48 69 48 73 / 20 20 10 10 10 0
Omak 47 66 45 72 44 74 / 20 40 10 10 10 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Blacksburg VA
758 PM EDT Wed Sep 21 2016
.SYNOPSIS...
An upper low will meander across the eastern Carolinas through
Thursday before finally weakening and shifting offshore by the end
of the week. High pressure will gradually build in from the west
Friday into Saturday. A backdoor cold front drops south through
the area late Saturday into Saturday night followed by cooler
high pressure Sunday into early next week.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 245 PM EDT Wednesday...
Closed low over the Southeast Coast will continue to interact with
the Post tropical remnants of Julia during the period. As been the
case for a couple of runs, the ECMWF and NAM remain slightly west
of the GFS. One of the forecast challenges is the western edge of
the moisture and the sharp gradient in showers. The HiResw-arw-east,
wrf-arw-rnk, RAP and HRRR support the mention of isolated to
scattered showers in southeast portions of forecast area this
afternoon into tonight.
The upper low remains fixed across the coastal Carolinas tonight
into Thursday morning. believe that shower coverage may wrap
tighter towards the coast tonight with drier air pushing into
northwest portions of forecast area. Cloud cover tonight will vary
from clear in the northwest to cloudy in the southeast. Lows tonight
will range from the mid 50s in the northwest mountains to the
mid 60s in the east.
The closed upper low will slowly weaken and lift northeast on
Thursday. The result of this transition will be even less coverage
of isolated showers across the south and southeastern portion of the
region. High temperatures Thursday will vary from the mid 70s in the
mountains to the lower 80s in the Piedmont.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 230 PM EDT Wednesday...
Persistent upper low will finally open up and shift northeast
Thursday night in response to ridging nudging east from the
Midwest. However may still be enough moisture around with the
deformation axis on the back of the coastal system to produce a
few added showers far southeast so left in an isolated mention
early.
Otherwise expecting a drier northerly flow to take shape under weak
high pressure later Thursday night into early Saturday. This should
bring clearing/sunny skies for late week into the weekend. However
passing 500 mb trough well to the north by Saturday will propel a
backdoor cold front toward the area Saturday afternoon and into parts
of the region Saturday night. This a bit slower than previous given
strong upper ridging overhead and warmth ahead of the front that should
slow it down until Saturday night. Other than perhaps some developing
post frontal low level cloudiness by late Saturday per the GFS, deep
moisture to remain limited so not including any pops with the boundary
for now. Given gradual 850 mb warming Friday and weak compression
ahead of the front Saturday, looks like will return to above
normal highs with mostly low/mid 80s both days with most surface
based cool advection holding off until Saturday night at this
point.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 130 PM EDT Wednesday...
High amplitude blocky pattern looks to evolve later in the weekend into
next week as potential cut off upper lows develop off New England and
across the upper Midwest. This could basically sandwich the area within
a sharp shortwave ridge axis between these two features pending exactly
where the upper block develops. Differences between models continue in
regards to strength of the upper systems and subsequent speed of
surface features in this setup. However still appears will see a rather
significant backdoor cold front drop south into the region by Saturday
night/early Sunday before the boundary fades crossing into the
Carolinas. Guidance still suggests some spotty shower potential Sunday
with the front aloft nearby and developing onshore flow. Thus thinking
more clouds and spotty shower pops Sunday and southern sections Sunday
night with a shallow moisture axis lingering but iffy.
Lots of uncertainty to take shape early next week as model spread
remains large in just how fast a second cold front to the west will be
able to slide east given eastern ridging in place. Latest 12Z GFS
has continued to make a shift toward the slower ECMWF from
overnight in keeping this slow moving front west of the mountains
through midweek. However these solutions remain much slower and
stronger than the GEFS which looks too weak/fast in lifting
support out to to the north, while spilling the front quickly
east. Overall the slower scenario would keep the area in more or
less a more stable low level wedge formation per high pressure to
the north under ridging aloft. Tendency in this setup likely to
lead to more clouds and spotty showers/drizzle including much
cooler temperatures into midweek. Therefore have trended in this
direction with highs below Mos, but still mostly 70s and lows 50s-
mid 60s, although highs by early week could be only in the 60s if
more widespread low clouds do materialize.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 750 PM EDT Wednesday...
Scattered to broken stratocumulus remained circulating around low
pressure off the South Carolina coast. The western edge of the MVFR
ceilings and light to moderate showers was east of a line from
KFVX to KGSO. Medium confidence that the precipitation and lower
ceilings will stay east of KLYH and KDAN through midnight. MVFR
clouds will then spread west to the Blue Ridge, including at KROA,
through sunrise. Otherwise a large cirrus shield covered much of
Virginia and northern North Carolina this evening. High clouds
will remain in place through Thursday.
Have included LIFR fog in the western river valleys, including at
KLWB. This will depend on the thinning and erosion of the high
clouds. The more cloud cover, the less likely dense fog will
develop. Any morning fog and low clouds will lift by mid morning,
return all taf sites to VFR conditions by Thursday afternoon.
GFS/HRRR and RAP guidance all keep a majority of any precipitation
along and south of the Virginia/North Carolina border on Thursday.
Extended aviation discussion...
The slight chance of MVFR showers will remain just east of KLYH and
KDAN through Thursday night. VFR conditions will prevail Thursday
night outside of late night/early morning fog/low clouds. GFS/ECMWF
have been consistent in filling and lifting out the low to the
northeast on Friday. VFR conditions will prevail on Friday.
A back-door cold front will come through the Mid-Atlantic region
on Saturday. High pressure will build in for Sunday. The chance of
precipitation or any sub VFR conditions will increase through the
day Sunday and into Sunday night.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH/RAB/WP
NEAR TERM...KK
SHORT TERM...JH
LONG TERM...JH
AVIATION...AMS/KK
Area Forecast Discussion
National Weather Service Billings MT
359 AM MDT Thu Sep 22 2016
.SHORT TERM...valid for Tdy and Fri...
Damp 3 days ahead for the region as well above normal moisture
content in the airmass will combine with a favorable upper level
flow to produce bursts of moisture into the region. Timing
continues to shift on the heaviest precipitation regarding this
system and latest guidance is decreasing precipitation amounts
today and Friday and shifting the emphasis to Friday night and
Saturday for south central and southeast Montana.
Expect persistent drizzle in a good portion of the region today as
upslope flow continues and guidance shows saturated boundary layer
moisture for most of the day. Expecting showers to move through
the area in southerly flow aloft but this activity appears to be
more hit or miss according to the latest HRRR. All models and HRRR
hint at a broader outbreak of convective activity early this
evening as a 700mb trowal rotates into the area around the
upstream low over southern Idaho.
Friday becomes complex as the upper low shifts towards the area
and generates cyclogenesis over northern Wyoming but this looks to
favor dry slotting for most of the area. There also may be a
subtle downsloping role due to such strong southerly 700mb flow.
Precipitation will increase Friday night as the low tracks into
the area and becomes upslopish at the mid levels for the Beartooth
and Absaroka Mountains with the best moisture spreading from there
into the adjacent plains.
Bottom line its a damp pattern and shower activity is going to
have precipitation amounts be widely varied with the best windows
for moisture this evening and Friday evening in the short term.
borsum
.LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...
Little in the way of changes for the extended forecast
period...with bulk of the period under influence of upper level
high pressure. There remains a bit of model uncertainty with the departure of
the upper level low pressure system...but generally agree last
remnant exiting to the east by Sunday evening.
Models indicate a good chance for precip across the bulk of the
region through the day Saturday...with best chances shifting
eastward overnight. Made a few minor adjustments for
timing...generally spreading likely pops back to the west for
Saturday morning...with improved model agreement. Expect outdoor
activities to be impacted from continued wet conditions. Expect
mostly clear conditions across the bulk of the region for
Sunday...as last remnants exit east through the
afternoon/evening. Warming trend should begin Sunday...as temps
climb back into the 60s.
Models are in pretty good agreement on a blocking ridge of high
pressure developing over the northeast CONUS by Sunday...which is
then progged to shift eastward through the middle of the work
week. Dry conditions should prevail...with a gradually warming
into the low 70s by the end of the period. AAG
&&
.AVIATION...
Areas of rain...drizzle...and fog are occurring across western
routes this morning. Flight conditions range from VLIFR in KBIL to
MVFR in KSHR and KLVM. VFR conditions prevail over eastern
routes...under partly cloudy skies this morning. Rain and
drizzle...with lowering cigs...are expected to overspread all
routes through today...with an isolated thunderstorm possible this
afternoon. Mainly MVFR conditions are expected through the day in
precip...but localized LIFR to VLIFR are possible in heavier
precip and areas of fog this morning and later tonight. Area
mountains will be mostly obscured through the period. AAG
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Fri Sat Sun Mon Tue Wed
-------------------------------------------------------
BIL 063 051/058 047/056 044/063 042/065 044/068 046/071
8/T 95/R 66/W 31/B 01/U 11/U 11/U
LVM 059 046/055 043/054 038/062 039/065 042/070 044/072
8/W 87/R 73/W 21/B 01/U 11/U 11/U
HDN 069 051/062 047/056 043/064 040/064 043/067 045/070
6/T 95/R 66/W 31/B 01/U 11/U 11/U
MLS 064 053/063 048/054 042/062 040/063 041/065 044/068
7/T 76/R 66/W 61/N 11/U 11/U 11/U
4BQ 066 053/070 048/056 041/061 037/061 039/065 042/070
4/T 74/R 56/W 41/B 11/U 11/U 11/U
BHK 060 049/061 048/054 041/057 039/059 040/061 041/064
5/T 57/R 65/W 52/W 11/U 11/U 11/U
SHR 070 052/065 045/054 041/060 039/062 040/066 042/070
7/T 85/R 66/W 31/B 11/U 11/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Cheyenne WY
237 AM MDT THU SEP 22 2016
.SHORT TERM...(Today through Friday night)
Issued at 215 AM MDT Thu Sep 22 2016
Obs show low clouds becoming more and more widespread for areas
to the east of the Laramie Range as light northeasterly sfc winds
transport llvl moisture into the area. Expecting cigs/vis to
continue to lower through 12Z with widespread LIFR/IFR conditions.
Extended fog all the way westward to the Laramie Range through mid
morning. Temps will be about 10 degrees cooler across the plains,
especially in the Nebraska Panhandle where low clouds will likely
persist through the early aftn. Pressure falls will occur through
the day over central WY with south-to-southeasterly winds becoming
breezy by late aftn into the evening. With the best forcing
remaining over the western half of WY, kept POPs mostly in the
20-40 percent range for areas along and west of the Laramie Range
through the evening. The HRRR and NCAR ensemble is not showing much
activity over the plains and especially the Nebraska Panhandle
where the airmass will be mostly capped.
Strong closed upper low is progged to move into southwest WY by
Friday aftn with cooling aloft and upper level diffluence
increasing for areas to the east of the Laramie Range. The models
continue to be in good agreement at showing showers and isolated
tstms developing over much of the plains of southeast WY into
portions of the Nebraska Panhandle by the aftn and evening, in the
convergence along the cold front. The cold frontal passage will
occur through the evening with breezy west to southwest winds
developing by late Friday night over southeast WY as the 700 mb
CAG-CPR gradient rises to 40-50 meters.
.LONG TERM...(Saturday through Wednesday)
Issued at 215 AM MDT Thu Sep 22 2016
More Autumn like weather in store for the weekend as low pressure
slowly moves through the area. Strong cold front associated with
the low looks to move through Saturday morning. 700mb temperatures
fall below freezing, down to -2C across the mountains to our west.
Pretty good bet that the Snowy and Sierra Madre Ranges will see
snow.
Going to see an increase in winds as well Saturday as GFS 700mb
winds at 55kts. 700mb Craig to Casper height gradient in excess of
60mtrs as well. If the low continues to track the way the GFS is
forecasting, we could be looking at more winds than precip with
this low.
Cold and windy conditions continue Saturday night into Sunday with
the upper low tracking into western North Dakota. 850mb winds in
the panhandle 40-45kts, so wind headlines will probably be needed
out that way, at least Advisory level if not warning.
Freezing temperatures for lows Monday morning across much of the
CWFA as skies clear out and winds ease. Looking at 20s for lows
across southeast Wyoming and low 30s across the Panhandle.
Start warming after Monday morning as 700mb temperatures climb
back above freezing and upper ridge begins to build back into the
area.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1101 PM MDT Wed Sep 21 2016
Stratus beginning to develop over northern Nebraska Panhandle and
will move southwest into the Cheyenne area by 09Z. Could see low
ceilings lasting most of the morning for our Nebraska Panhandle
airports as well as KCYS. Generally followed latest HRRR guidance
on timing of stratus onset and duration.
&&
.FIRE WEATHER...
Issued at 215 AM MDT Thu Sep 22 2016
No fire weather concerns through the end of the week. Temperatures
will cool over the next few days, and especially after Friday
evening behind a cold front. Minimum afternoon humidity values
will mostly be above 30 percent. Along with an increase in cloud
cover, there will be a chance of showers and thunderstorms through
Friday, mostly during the afternoons and evenings.
&&
.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&
$$
SHORT TERM...ZF
LONG TERM...GCC
AVIATION...GCC
FIRE WEATHER...ZF
Area Forecast Discussion
National Weather Service Duluth MN
320 AM CDT THU SEP 22 2016
.SHORT TERM...(Today through Friday)
Issued at 320 AM CDT Thu Sep 22 2016
Surface high pressure over Saskatchewan/Manitoba will shift east
into northern Ontario today into Friday, so the Northland`s dry
northeast flow today will become easterly Friday. Expect generally
seasonal weather.
Today...An area of low pressure in the Central Plains had a
trough/stationary front extending to northwest Wisconsin as of
early this morning, and it could be the trigger for showers and
some thunder today. However, the radar trends have been shifting
the precipitation farther south, suggesting drier weather for the
Northland. The dry RAP seems to be following the latest radar
trends the best among the rest of the models, so leaned on the
drier RAP. Now there only remains low chances of showers and
thunder across parts of northwest Wisconsin. One feature the
models have not captured has been the showers across the Arrowhead
early this morning. These showers seem to be tied to a mid-level
deformation band...which disappears later this morning. Highs
today will be in the lower 60s.
Tonight...There will be clearing tonight. Lows will range the
lower 40s across northern Minnesota to the upper 40s and lower
50s across the southern forecast area. Friday`s highs will be in
the lower 60s.
.LONG TERM...(Friday night through Wednesday)
Issued at 320 AM CDT Thu Sep 22 2016
Focus is on next low pressure system which will lift a warm front
across the upper midwest Friday night into Saturday. This front
and associated warm air advection is expected to be the focus for
showers and a few thunderstorms. There will be a breif dry period
late in the day saturday, as models suggest a dry slot pushes into
the Northland. However, the break will be short lived as the cold
front sweeps across the region, triggering another round of
showers and thunderstorms Sunday.
The rain chances will remain in the forecast into next week as a
slow moving upper level low tracks across northern minnesota. The
GFS bufr soundings show steep lapse rates associated with the low
as 850 hPa temps fall into the single digits. Although timing
differs with the gfs showing the slower trend, long range model
suggest high pressure builds into the region for the later half of
the week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 320 AM CDT Thu Sep 22 2016
A stationary front will gradually slide southeastward from southern
MN and central WI into northern IA and southern WI by Thursday
evening. This will result in showers and storms impacting KHYR and
potentially moving into KDLH/KBRD tonight. This will bring MVFR to
IFR ceilings or lower as the lower levels moisten per the latest
RAP/HRRR. In the heavier showers/storms expect visibility
reduction, with visibility lowering most likely at KHYR. Kept in
the MVFR range based on surrounding observations, but lower is
possible.
Will gradually see conditions improve to VFR at KDLH/KBRD/KHYR as
the front slides away allowing drier air to move in from the
northwest. Expect VFR conditions to develop late in the TAF period
for KHYR and around 12Z to 15Z for KDLH/KBRD.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 63 49 61 52 / 10 10 10 50
INL 64 42 65 50 / 0 0 0 50
BRD 67 52 64 56 / 10 10 20 40
HYR 64 52 64 54 / 40 10 10 40
ASX 62 51 63 52 / 20 10 0 40
&&
.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...Small Craft Advisory until midnight CDT Friday night for LSZ121-
141>148.
&&
$$
SHORT TERM...Grochocinski
LONG TERM...Graning
AVIATION...WL
Area Forecast Discussion
National Weather Service Goodland KS
300 AM MDT THU SEP 22 2016
.SHORT TERM...(Today through Saturday night)
Issued at 300 AM MDT Thu Sep 22 2016
Early morning RAP and satellite analysis show a large scale
trough over the western US, with a closed center near the
California/Oregon border. Ridging extends across the central US
into the Northern Rockies, with SW flow over the intermountain West.
Today-Tonight: A quasi-stationary front will remain either over the
northern part of our CWA or just north of our CWA complicating temp
forecast. WAA south of this feature should support highs in the 90s,
while north highs may struggle to reach the low 80s (depending on
cloud cover). Precip chances are minimal due to storm track to our
west, and a very dry/stable in place over much of our CWA. There is
a weak precip signal in high resolution guidance in our west
associated with elevated instability above dry adiabatic layer. A
few thunderstorms may develop and attempt to track northeast late
this afternoon and evening with steepening lapse rates near the
surface trough along the CO border ahead of front, but confidence
is low. I introduced slight chances in eastern CO for now.
Friday-Friday night: Large scale forcing increases with entrance
region of jet ahead of large scale trough transitioning over our
CWA. Dry line develops near the CO border and could act as focus for
possible thunderstorm development early in the afternoon Friday
before main period of forcing occurs Friday evening. Biggest question
is going to be low level moisture along/east of this trough and
impact on instability. NAM currently shows ML CAPE around 1500 J/KG
which could be sufficient for an elevated risk of severe
thunderstorms considering the very high shear values ahead of trough
(50kt+ effective shear values). Based on soundings if favorable CAPE
materializes we may see potential for thunderstorms to merge in a
cluster or squall line with a potential for a widespread severe wind
event. Severe hail may be a secondary threat at this point, unless
we see better CAPE profiles than currently advertised.
Other forecast issue of concern Friday would be potential for near
critical fire weather conditions in eastern Colorado as windy
conditions are expected (gusts 40-45 mph possible). There is enough
spread on Tds between models but good mixing may support RH values
dropping below 20 percent in our west (behind dry line). Will need
to monitor.
Saturday-Saturday night: Post frontal air mass with subsidence
building from the northwest should preclude precip chances in all
but our far east/southeast. Expect temperatures to return to near
seasonal normals (highs around 80 and lows in the 40s to the lower
50s).
.LONG TERM...(Sunday through Wednesday)
Issued at 227 AM MDT Thu Sep 22 2016
The long term period is looking to be dry for the entire period.
Yet, there are some major discrepancies between the GFS and EC. The
current model run for the GFS has an exiting deep trough impacting
the region through Tuesday night with a ridge building in behind it.
The EC is much different, with the bulk of that trough moving out of
the region Sunday and then developing a closed low off the trough
over the southwestern states. That closed low is embedded under a
ridge that is over the region. So as far as the models go, there is
little confidence in which one will hold true at this point. One
thing to mention is that Sunday and Monday nights could potentially
see temperatures drop into the mid to upper 30s in some locations.
Will keep an eye on this due to the possibility for a frost
advisory. Otherwise, high temperatures are expected to be in the 60s
and 70s through the entire period, which is about average or just
under for this time of year.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1127 PM MDT Wed Sep 21 2016
Main aviation concern will be the possibility of low clouds and
reduced visibility in fog overnight and into Thursday morning. A
cold front will sag southward tonight and both are expected to
develop in the post frontal low level upslope environment.
Conditions will gradually improve through Thursday morning.
&&
.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...CLT
AVIATION...024
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
329 AM EDT Thu Sep 22 2016
.SYNOPSIS...
A weak area of low pressure lingering along the coast of the
Carolinas today will drift east on Friday. A broad upper ridge and
surface high pressure will build over the region during the weekend
as temperatures rise well above normal again.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 250 AM Thu: Still dealing with the effects of easterly flow
around sfc/upper low over the Carolina coast. Pockets of light
showers continue to move WSW from the Triangle to the Piedmont
Triad, and while they thin out as they move into the drier air
over our CWFA, they are beginning to make inroads. HRRR expects
they will reach the Hwy 321 corridor before fizzling out around
daybreak. A chance-range PoP is retained over the ern zones thru
the morning. Thicker and lower cloud deck will also move in this
morning, and guidance consensus indicates that will hang around
well into the afternoon. Max temps are impacted, being just a
couple degrees above normal across most of the area--the upper
Savannah valley is expected to remain sunnier and still reach the
upper 80s in spots.
While some pockets of light stratiform rain will move through the
Piedmont at times today, convection is expected to be a bit more
widespread than yesterday, on account of slightly improved lapse
rates. Meso models depict isolated convection over the Blue Ridge
and parts of the lower Piedmont, similar to what verified yesterday,
though with a little more QPF. Thunder is still too unlikely to
mention. The low wobbles slightly northeast along the coast tonight,
keeping the low level pattern pretty much the same. High pressure
strengthens a bit over the Mid-Atlantic and down the southern Apps;
this holds back the advance of clouds and precip, chances of which
taper off overnight. Min temps across the area will be around 10
degrees above normal.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
As of 230 AM EDT Thursday...still expecting the weekend to be
relatively benign weather-wise...although quite warm. The model
guidance continues to show the old upper low opening up and filling
along the Carolina coast on Friday, although at least some remnant
of the upper system appears to be left to drift westward along the
Gulf Coast, underneath the upper ridge, on Saturday. Whether or not
this feature is the actual upper low should be immaterial, as the
western Carolinas come under the influence of the amplifying upper
ridge from Friday thru Saturday. The plume of wrap-around moisture
might be sufficient to maintain a few showers over the eastern zones
early in the day on Friday, but this will get pushed off to the east
in the afternoon. Some instability over the SW mountains of NC might
allow for a few showers over the higher terrain in the afternoon.
Otherwise, expect most locations to remain dry with high temps
climbing five degrees or so warmer than Thursday, back to almost
Summer-like heat. That trend will continue into Saturday with only a
few ridge-top showers able to break through a strong cap. High temps
should be well above normal...and very much like summer. Uncertainty
begins to creep in from the east on Sunday with some indication that
surface high pressure moving across the Gt Lakes will impose an
easterly flow that will bring some Atlantic moisture over the
region. Fcst soundings from the GFS show the low level moisture
allowing for more sfc-based buoyancy...enough to warrant a chance of
precip over the mtns and foothills by afternoon. This seems
reasonable enough to keep a small chance in the fcst. Temps may be
held in check by increased cloud cover Sunday afternoon, at least
over the NC part of the fcst area.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
As of 315 AM Thursday...you would find it difficult to remember a
time in your recent memory when the operational runs of the medium
range models had less run-to-run continuity and less agreement with
the upper pattern as you see by the middle of next week. Whether the
pattern will remain progressive or amplified or become blocked is
difficult to determine right now, leading to much greater
uncertainty than usual for this time of year. There is at least some
agreement that at some point a frontal boundary will get strung out
close to the fcst area in the middle or late part of the week, so
there is hope of getting some much-needed rain. Details are very
sketchy though. At this point, prefer to not make any changes in the
medium range and will look toward hopefully seeing some consistency
and/or trend in the next model cycle.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
At KCLT: Low pressure over the eastern Carolinas will sustain
northeasterly flow over the field thru the period. MVFR to IFR
stratus will expand westward thru central NC early this AM, along
with bands of light showers. MOS guidance generally progs KCLT
seeing IFR by daybreak, whereas raw models (including hi-res runs)
generally favor low MVFR. The best performing guidance in this
pattern has been raw, but with IFR under 100 SM away, I can`t deny
the possibility. Hence TEMPO IFR for now; will refine this at 09z
per latest guid/obs. The moist layer is deep enough that daytime
improvement will be much slower than usual. Lapse rates are a tad
more favorable than those Wed, so SCT SHRA are expected this aftn.
Elsewhere: MVFR cigs are expected to advect over KHKY/KGSP/KGMU
around dawn or a little later. KHKY has a small chance at IFR,
with same reasoning as outlined for KCLT above. Some sprinkles
are possible in the morning as bands of better forcing round the
low. Also, once cigs finally lift and/or scatter a bit, there
should be more coverage of aftn SHRA than the past couple days,
though still too isolated to mention in TAFs. Winds mainly NE thru
the period, with no restrictions anticipated tonight prior to 06z.
Outlook: Meandering low pressure along the Carolina coast will
persist thru Friday. This will allow isolated to scattered diurnal
convection to continue especially east of I-77, and periodic
chances for restrictive cigs. Meanwhile, a new cold front will be
approaching from the northeast Sunday, but with sparse precipitation
expected at this point.
Confidence Table...
07-13Z 13-19Z 19-01Z 01-06Z
KCLT High 91% High 97% High 97% High 100%
KGSP High 99% High 88% High 100% High 100%
KAVL High 84% High 94% High 100% High 100%
KHKY High 98% High 89% High 100% High 100%
KGMU High 100% High 88% High 100% High 100%
KAND High 100% High 90% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...PM
NEAR TERM...Wimberley
SHORT TERM...PM
LONG TERM...PM
AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Mobile AL
445 AM CDT THU SEP 22 2016
.NEAR TERM /Now Through Thursday night/...Surface high pressure ridge
that has been over the region builds slightly today and tonight,
resulting in a generally light and variable wind flow across the
region (although becoming predominately southwesterly near shore late
this afternoon with daytime heating developing a weak sea breeze
circulation). In the upper levels 500mb low over the Carolina`s early
this morning will likely open into a trof by tonight...with upper
high pressure noted just to the west of the fcst area over eastern
Texas and Louisiana. Models indicate that the resultant north to
northeast flow aloft may allow weak shortwave energy to move south
over or near western portions of fcst area today. With this...we
could see some isolated afternoon showers or storms over the western
zones (primarily from Mobile/Baldwin counties and points northward
and westward). ECMWF advertises essentially no PoP today...while GFS
shows very isolated. Even Hi-Res HRRR indicates very isolated
coverages...so opted to not include a rain chance for today(although
a very isolated shower or storm could be possible over the western
zones as mentioned above). Expect temperatures to again heat up into
the lower 90s over interior locations today (which is nearly 10
degrees above normal) and upper 80s to near 90 at the coast (also
above normal...by 6-8 degrees for those locations). Low temperatures
tonight expected to be above normal as well (by 5 to 10 degrees or
so) ranging from upper 60s to near 70s inland to low to mid 70s at
the coast. 12/DS
.SHORT TERM /Friday Through Saturday night/...Several strong
shortwaves swing slowly east over the western Conus to the Rockies,
with a piece breaking off an forming a closed low over the Desert
Southwest. More energy organizes into a deep upper low over the
Canadian Maritimes through the same period, and in combination with
the western trough, builds a strong upper ridge over the Mississippi
River Valley. The opening upper system over the Carolina coast
continues to weaken into a weak shortwave system, but remains strong
enough to create a surface circulation strong enough to disrupt a
surface ridge stretching south along the Appalachians into Saturday
night.
For the forecast, subsidence from the building upper trough will
continue to keep temperatures will above seasonal levels (low to mid
90s for highs, upper 60s to low 70s for lows). With the surface ridge
disrupted by a weak surface low/circulation, a diurnally driven
daytime Gulf breeze/ night-time land breeze setup will create a few
offshore shra/tsra, which will move inland with the Gulf breeze. As
the Gulf breeze brings increasing moisture inland, am expecting
precip chances to slowly creep up into the weekend.
/16
.LONG TERM /Sunday Through Wednesday/...The extended continues to be a
bear, with inconsistency between models and temporal inconsistencies.
The latest medium range model runs are consistent in advertising a
piece of energy breaking off the southern end the western upper
trough, but the handling of the northern end is the where the
problems lies. The GFS in now advertising the western trough working
with the southward shifting Canadian upper low to build an upper
trough over the Eastern Seaboard (like the ECMWF was advertising
yesterday), whilst todays ECMWF run is advertising the northern piece
of energy moving east over the Northern Plains/Great lakes region to
the Mid Atlantic region. Even with the ECMWF advertising a flattening
of the upper ridge, it is keeping it strong enough to advertise a
warmer solution than the GFS. The difference is closer than
yesterday, but is still significant enough to keep from saying they
are in general agreement. Both are advertising a weak surface front
being pushed towards the fa (from the nw by the GFS, from the n by
the ECMWF), then stalling it close (ECMWF) or over (GFS) the fa by
Wednesday evening. The GFS is also advertising a wetter solution then
ECMWF, with the boundary stalled over the fa. Have went with a
blended approach for the forecast, with temps remaining well above
seasonal levels and chance of rain a bit above seasonal.
/16
&&
.MARINE...A high pressure ridge will persist over and just north of
the coastal waters through them remainder of the week and into the
early part of next week. Winds will remain light (generally 10 knots
or less) and sea states will remain small (occasionally 1 to 2 feet
at the most...generally 1 foot or less). Only isolated to ocnly
scattered showers and storms over the marine area. 12/DS
&&
.PRELIMINARY POINT TEMPS/POPS...
Mobile 92 71 93 71 / 10 0 20 10
Pensacola 90 74 91 73 / 10 0 20 10
Destin 89 77 90 75 / 10 0 20 10
Evergreen 92 70 93 69 / 10 0 10 0
Waynesboro 93 70 92 68 / 10 10 10 0
Camden 92 70 93 68 / 10 10 10 0
Crestview 93 69 95 68 / 10 0 10 10
&&
.MOB Watches/Warnings/Advisories...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Phoenix AZ
250 AM MST THU SEP 22 2016
.SYNOPSIS...
Showers and a few thunderstorms will be possible today along and
ahead of a cold front moving through the region. This front will
bring gusty winds, drier air, and slightly cooler temperatures for
the remainder of the week. Breezy, but otherwise quiet weather will
be the rule for the weekend and into early next week along with a
warming trend.
&&
.DISCUSSION...
Impressive and unseasonably cool upper low continued to take shape
along the northern California and Pacific NW coast early this
morning, and latest guidance is consistent in calling for this low
to progressively dive to the southeast today and push into the
desert southwest bringing scattered to numerous showers along with
embedded thunderstorms to the lower deserts during the day today.
Ample moisture is already in place across the lower deserts; surface
dewpoints at 2 am were mostly in the mid to upper 60s with values as
high as low 70s across portions of the lower Colorado River valley.
IR imagery showed variable amounts of low to mid cloud over the
western AZ and southeast CA deserts although current radar showed
little in terms of shower activity. Through about sunrise, QG
forcing is not especially strong and local models do not really show
much convection developing until around 12z or so this morning.
As the main upper low center drops into central Nevada this
afternoon, a well defined frontal band oriented mostly north to
south will push across the western AZ deserts and into south central
arizona; some of the best QG forcing/Q convergence fields move into
the central deserts this afternoon and the associated UVV will act
on a very moist airmass to generate widespread showers with embedded
thunderstorm. Latest HRRR depicts this scenario very nicely and our
forecast timing of the front will mirror the HRRR timing. POPs have
been raised into the 50-60 percent ballpark across much of the
central deserts with the best chances for rainfall in the greater
Phoenix area to occur during the afternoon today. These higher POPs
are supported by the latest NAEFS POPs guidance.
Gusty west winds are expected to develop over the western deserts
this afternoon behind the front, with the strongest winds likely to
occur over favored areas of Imperial county; peak gusts to 35 mph
are likely. There may be some patchy blowing dust occurring due to
the wind, but recent rains in the area will limit the potential for
any significant dust and as such we will not mention blowing dust in
our forecast grids at this time. As far as temperatures go today,
with thickness values lowering to around 576dm and with considerable
lower clouds and showers in the area, high temperatures will fall to
well below seasonal normal values with many lower AZ deserts falling
into the upper 80s to low 90s. Phoenix should see a high around 90
today which would be 8 degrees below normal.
Upper low center will quickly move east into Utah tonight and most
of the strong QG forcing will shift well east of Phoenix; as such
POPs tonight will focus across the higher terrain of southern Gila
County with values as high as 40 percent or so. Rain chances will
quickly diminish this evening over the south central deserts; rain
chances in Phoenix will lower to around 10-15 percent after midnight.
On Friday, the main upper low is forecast to quickly lift off to the
northeast but a much drier and more subsident northwest flow aloft
will overspread the deserts. Outside of a lingering slight chance of
showers over southern Gila County we can expect generally sunny
skies over the lower deserts with continued below seasonal normal
high temperatures. PWAT values are forecast to fall to around one
quarter of inch over much of the lower central deserts by Friday
afternoon and the surface dewpoints in the Phoenix area will fall
from the mid to upper 60s today into the upper teens to mid 20s.
Over the weekend and into next week, dry conditions are forecast
area wide with no threat of precipitation. A large upper ridge will
initially amplify along the west coast giving a dry northerly flow
to the area but early next week the ridge will flatten somewhat but
continue giving dry northwest flow into the lower deserts. Expect
generally sunny days and clear nights this weekend into the middle
portion of next week along with a gradually warming trend. High
temperatures will climb into the mid to upper 90s over most of the
lower deserts by the early to middle part of next week.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
After little aviation impacts this evening, the potential for lower
cigs and frontal rain bands will be the main aviation
problem/challenge for Thursday. Cigs could drop to a 6K ft level as
early as sunrise Thursday morning, with more likely filling and
development though the morning hours. Confidence is good that a band
of rain showers along with gusty SW winds and lower cigs 5-6K ft
will pass through terminal sites Thursday afternoon before rapid
improvement Thursday evening.
Southeast California/Southwest Arizona including KIPL and KBLH:
Aviation conditions will continue to improve overnight though cigs
in a 8K-12K ft range should prevail through Thursday morning. The
primary aviation problem will be gusty W/SW winds Thursday afternoon
behind a cold front. Frequent gusts over 25kt will be likely, and
brief periods of winds nearing 35kt are possible around and west of
KIPL.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Friday through Tuesday...
High pressure will move into the region and bring very dry air along
with temperatures near or just below seasonable values. Minimum
humidity values will drop into the teens all areas Saturday/Sunday,
then show a slight upward trend into next week. Breezy winds can be
expected Friday through Monday. Critical thresholds may be touched
at times, especially across southeast California and the Lower
Colorado River Valley.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter reports may be needed locally Thursday afternoon across the
Phoenix area.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...CB
AVIATION...MO
FIRE WEATHER...Iniguez
Area Forecast Discussion
National Weather Service Pueblo CO
1126 PM MDT WED SEP 21 2016
.SHORT TERM...(This evening through Thursday)
Issued at 255 PM MDT Wed Sep 21 2016
...A Warm and Breezy Thursday...
Current water vapor imagery and upper air analysis is indicating
moist southwest flow aloft across the state, as remnant moisture
from tropical system Paine continues to lift out across the region.
Water vapor imagery is also indicating drier air embedded within the
flow across the Desert Southwest moving into western New Mexico and
western Colorado, ahead of an upper trough digging across the West
Coast at this time. Regional radars indicating isolated to scattered
showers lifting north and east across the region, with a few
thunderstorms across northwestern New Mexico at this time.
Tonight and tomorrow...Latest models remain in fairly good agreement
with southwest flow aloft slowly increasing across the region
through the day tomorrow, as digging upper trough across the West
Coast carves out an upper low across the Great Basin tomorrow
afternoon.
With that said, should continue to see showers with a few embedded
thunderstorms moving across the area through the rest of the
afternoon and into the early evening, with HRRR remaining consistent
with the best coverage of storms being across the Pikes Peak region
and the Raton Mesa region into Baca County. Showers and storms to
diminish through the late evening, with loss of solar heating.
However, could see some showers developing across the ContDvd and
especially the southwest mountains, into early tomorrow morning,
with increasing orographic flow. Overnight lows to be at or above
seasonal average, especially across the eastern plains, where lee
troughing will keep breezy southerly winds across the far se plains
overnight.
Will see more sun across the area early tomorrow, and with the
increasing flow aloft and lee troughing across the plains, should
see breezy southerly winds mixing across the area through the late
morning and afternoon. Mid and upper level moisture slowly increases
across the area again ahead of the Great Basin system, along with
southerly low level winds across the plains keeping low level
moisture in place, owning to another round of isolated to scattered
afternoon showers and storms, with the best coverage over and near
the higher terrain. Models continue to suggest near record high
temperatures in the 80s to lower 90s across the plains for tomorrow,
with highs in the 60s and 70s across the higher terrain and mainly
40s and 50s at the peaks. Current records for tomorrow are 85F at
ALS...88F at COS and 93F at PUB.
.LONG TERM...(Thursday night through Wednesday)
Issued at 255 PM MDT Wed Sep 21 2016
...Critical Fire Weather conditions I-25 corridor...Severe
thunderstorm potential eastern plains...and snow possible higher
mountains Friday...
Western U.S. upper low will move across the Great Basin Thursday
night before lifting northeastward into WY and MT Friday and
Friday night. Deep southerly flow across the plains will advect 50
dewpoints northward into the southeast plains Thurs night into
Friday morning. Initially will see some showers confined to the
mountains Thurs night and Fri with snow levels down to around
12kft at times along the continental divide. Dry air moves in
Friday afternoon as the trof axis moves across...which shallows out
the moisture along the continental divide. By this time...westerly
winds will be spreading eastward into the plains...sharpening up a
dry line just east of the I-25 corridor. All areas will see gusty
west to southwest winds west of the dry line...and gusty southerly
winds to the east of the dry line. CAPE values could be up to
around 1000 J/kg (according to the NAM12) with deep layer shears
around 30-40 kts. This will lead to a potential for severe
thunderstorms across the eastern counties including...Kiowa...
Bent...Prowers and Baca. Severe wind gusts and large hail will be
the primary storm threats.
To the west...RHs dropping to around 15 percent...and
the dry fuels will combine with gusty winds up to 40 mph to
create the potential for critical fire weather conditions Friday
afternoon and evening along the I-25 corridor. There are still
some questions as to the position of the dry line and how low
surface dew points will drop...however NAM12 seems too moist which
is its bias...and have leaned grids towards the drier GFS and EC
solutions for locations west of the dry line. For now have
restricted the Fire Weather Watch to the southern I-25 corridor
and a couple counties bordering to the east...but its possible
that the watch may need to be expanded northward and eastward a
bit more. Will let later shifts make any needed adjustments.
As the trof axis lifts out to the north Friday night...should see
drying conditions from west to east overnight. Any snowfall into
the mountains looks brief and relatively light...with spotty
amounts of an inch or two possible above 12kft. The San Luis
Valley could see a fairly widespread hard freeze Friday night.
While the main upper low lifts off to the northeast...more energy
digging into the base of the trof across CO will keep generally
unsettled weather over the region through the weekend. A cold
front will drop through the region on Saturday with another surge
of colder air for Saturday night. Models keep majority of
precipitation across the southeast mountains and adjacent plains
where H7 temperatures dropping to 0 to -2C could drive snow levels
down to 9kft or a tad lower Sat night and again Sunday night. EC
and GFS differ with QPF during these periods...with EC on the
wetter side. Hard to say at this point how much snow will fall
across the southeast mountains...but at this point a few inches
of wet snow across the higher elevations look possible as GFS has
trended back towards a wetter solution.
Models shift the upper low eastward into the plains early next
week...though differ with the track as GFS keeps the upper low
center to the north across the Dakotas through Wed...while ECs
track is farther south. Either way...CO is on the back side of the
system with drier but cooler northerly flow. This will keep below
normal temperatures across the region through the longer ranges.
-KT
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1126 PM MDT Wed Sep 21 2016
VFR conditions expected to persist at COS, PUB and ALS over the next
24 hours. Mid and high level moisture streaming across the 4
Corners will continue intermittent cloud cover across all of the
forecast area overnight. Isolated showers over the S Sangres will
continue tonight into the early morning hrs. Otherwise, look for
convection to fire up over the higher terrain by late morning,
then isolated convection will spread across the TAF sites of KALS
and KCOS through the aftn. Surface winds will persist out of the
south. Moore
&&
.PUB Watches/Warnings/Advisories...
Fire Weather Watch from Friday afternoon through Friday evening
for COZ227>232.
&&
$$
SHORT TERM...MW
LONG TERM...KT
AVIATION...MOORE
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
323 AM CDT THU SEP 22 2016
.SHORT TERM...(Today and tonight)
Issued at 319 AM CDT Thu Sep 22 2016
Current water vapor shows several weak mid level shortwaves moving
out over the plains this morning. The associated weak isentropic
lift is expected between now and late morning mainly over north
central and far northern KS. This is where isolated to scattered
showers and possibly some thunder may occur. The GFS seems quite
bullish with the amount of QPF especially given the fact no other
models agree with these amounts. Also, there is a small complex of
decaying storms over southwest KS. Any remnant MCV could reach north
central KS later this morning and bring a slight chance for showers
as well. Only the HRRR is showing this activity will reach the
forecast area. After late morning the chances should diminish. High
clouds associated with the tropical moisture fetch will stick around
until at least the evening. Highs today look to reach the upper 80s
to lower 90s with dew points in the upper 60s. Winds will become
gusty out of the south again today mainly during the late morning
and early afternoon. Quiet weather continues tonight with partly
cloudy skies and lows in the mid 60s.
.LONG TERM...(Friday through Wednesday)
Issued at 319 AM CDT Thu Sep 22 2016
Friday, the downstream ridge across the plains and mid MS river
valley will amplify as the upper trough across the western US
deepens. Friday will be another warm day with south-southeast winds
of 15 to 25 MPH. Highs will reach the upper 80s to lower 90s.
Thunderstorms that develop across western KS during the early
evening hours may reach the western counties of the CWA late Friday
night.
Saturday through Sunday night, An intense upper level trough across
the Western US on Friday will begin to shear apart as if moves east
across the plains. There will be stronger ascent ahead of the
positive tilt upper wave as it moves east across KS Saturday night
through Sunday night. There will be a good transport of deep gulf
moisture northeast across eastern KS at 850mb, ahead of the upper
trough Saturday night through Sunday. Both the GFS and ECMWF
forecast a widespread QPF of 1 to 3 inches across the CWA. If the
rain falls over a 24 to 36 hour period then there will probably only
be minor flooding possible. However, stronger thunderstorms may
train from southwest to northeast across portions of the CWA
Saturday evening into Sunday morning which may produce a greater
potential for flash flooding. The next few shifts will have to watch
the potential for flooding Saturday night into Sunday.
Since the upper trough begins to shear apart as it moves into the
plains, the 0-6 KM effective shear weakens during the afternoon
hours. Given MLCAPES of 1500-2500 there could be a few pulse severe
storms that develop along the surface front across west central KS,
then may move into the western counties of the CWA before the
stronger ascent moves east along the front and develops a line
of showers and thunderstorms during the evening hours of Sunday.
The GFS is more progressive moving the upper trough east across the
plains and the heavier rain may move southeast of the CWA during
the mid morning hours of Sunday. If the GFS were to verify the
surface front will move southeast across the CWA during the early
morning hours of Sunday and skies may clear from northwest to
southeast during the afternoon hours. The ECMWF is slower moving the
positive tilt H5 trough across the plains on Sunday and keeps
widespread showers and elevated thunderstorms across much of the CWA
through the day Sunday and into Sunday night as isentropic lift
continues north of the surface cold front.
Monday through Tuesday, Once again the ECMWF and GFS solutions
diverge as the ECMWF continues to amplify the southern section of
the upper level trough across southwest NM, then lifts the H5 trough
northeast across the plains by mid week. The GFS keeps the northern
branch of the H5 trough amplified as it shifts northeast across the
Great Lake States. If the ECMWF verifies there will be at least a
slight chances for showers and thunderstorms through the week. If the
GFS were to verify then expect dry conditions through the week.
Highs will be around 70 on Monday with temperatures warning into the
mid to upper 70s by Thursday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1154 PM CDT Wed Sep 21 2016
VFR conditions are likely through the TAF period with increased
wind speeds during the late morning through afternoon hours. 2000
foot AGL winds will be in the 30-35 kt range through 12Z, which
should be slightly less than LLWS criteria.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Sanders
LONG TERM...Gargan
AVIATION...Barjenbruch
Area Forecast Discussion
National Weather Service Cheyenne WY
509 AM MDT THU SEP 22 2016
.SHORT TERM...(Today through Friday night)
Issued at 215 AM MDT Thu Sep 22 2016
Obs show low clouds becoming more and more widespread for areas
to the east of the Laramie Range as light northeasterly sfc winds
transport llvl moisture into the area. Expecting cigs/vis to
continue to lower through 12Z with widespread LIFR/IFR conditions.
Extended fog all the way westward to the Laramie Range through mid
morning. Temps will be about 10 degrees cooler across the plains,
especially in the Nebraska Panhandle where low clouds will likely
persist through the early aftn. Pressure falls will occur through
the day over central WY with south-to-southeasterly winds becoming
breezy by late aftn into the evening. With the best forcing
remaining over the western half of WY, kept POPs mostly in the
20-40 percent range for areas along and west of the Laramie Range
through the evening. The HRRR and NCAR ensemble is not showing much
activity over the plains and especially the Nebraska Panhandle
where the airmass will be mostly capped.
Strong closed upper low is progged to move into southwest WY by
Friday aftn with cooling aloft and upper level diffluence
increasing for areas to the east of the Laramie Range. The models
continue to be in good agreement at showing showers and isolated
tstms developing over much of the plains of southeast WY into
portions of the Nebraska Panhandle by the aftn and evening, in the
convergence along the cold front. The cold frontal passage will
occur through the evening with breezy west to southwest winds
developing by late Friday night over southeast WY as the 700 mb
CAG-CPR gradient rises to 40-50 meters.
.LONG TERM...(Saturday through Wednesday)
Issued at 215 AM MDT Thu Sep 22 2016
More Autumn like weather in store for the weekend as low pressure
slowly moves through the area. Strong cold front associated with
the low looks to move through Saturday morning. 700mb temperatures
fall below freezing, down to -2C across the mountains to our west.
Pretty good bet that the Snowy and Sierra Madre Ranges will see
snow.
Going to see an increase in winds as well Saturday as GFS 700mb
winds at 55kts. 700mb Craig to Casper height gradient in excess of
60mtrs as well. If the low continues to track the way the GFS is
forecasting, we could be looking at more winds than precip with
this low.
Cold and windy conditions continue Saturday night into Sunday with
the upper low tracking into western North Dakota. 850mb winds in
the panhandle 40-45kts, so wind headlines will probably be needed
out that way, at least Advisory level if not warning.
Freezing temperatures for lows Monday morning across much of the
CWFA as skies clear out and winds ease. Looking at 20s for lows
across southeast Wyoming and low 30s across the Panhandle.
Start warming after Monday morning as 700mb temperatures climb
back above freezing and upper ridge begins to build back into the
area.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 507 AM MDT Thu Sep 22 2016
Followed latest HRRR guidance on the 12Z TAFs. Looks like stratus
will stay in across the Nebraska Panhandle and KCYS through 18Z
before breaking. Low clouds expected to return tonight, maybe a
little earlier than when it formed this morning.
&&
.FIRE WEATHER...
Issued at 215 AM MDT Thu Sep 22 2016
No fire weather concerns through the end of the week. Temperatures
will cool over the next few days, and especially after Friday
evening behind a cold front. Minimum afternoon humidity values
will mostly be above 30 percent. Along with an increase in cloud
cover, there will be a chance of showers and thunderstorms through
Friday, mostly during the afternoons and evenings.
&&
.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&
$$
SHORT TERM...ZF
LONG TERM...GCC
AVIATION...GCC
FIRE WEATHER...ZF
Area Forecast Discussion
National Weather Service Duluth MN
652 AM CDT THU SEP 22 2016
.SHORT TERM...(Today through Friday)
Issued at 320 AM CDT Thu Sep 22 2016
Surface high pressure over Saskatchewan/Manitoba will shift east
into northern Ontario today into Friday, so the Northland`s dry
northeast flow today will become easterly Friday. Expect generally
seasonal weather.
Today...An area of low pressure in the Central Plains had a
trough/stationary front extending to northwest Wisconsin as of
early this morning, and it could be the trigger for showers and
some thunder today. However, the radar trends have been shifting
the precipitation farther south, suggesting drier weather for the
Northland. The dry RAP seems to be following the latest radar
trends the best among the rest of the models, so leaned on the
drier RAP. Now there only remains low chances of showers and
thunder across parts of northwest Wisconsin. One feature the
models have not captured has been the showers across the Arrowhead
early this morning. These showers seem to be tied to a mid-level
deformation band...which disappears later this morning. Highs
today will be in the lower 60s.
Tonight...There will be clearing tonight. Lows will range the
lower 40s across northern Minnesota to the upper 40s and lower
50s across the southern forecast area. Friday`s highs will be in
the lower 60s.
.LONG TERM...(Friday night through Wednesday)
Issued at 320 AM CDT Thu Sep 22 2016
Focus is on next low pressure system which will lift a warm front
across the upper midwest Friday night into Saturday. This front
and associated warm air advection is expected to be the focus for
showers and a few thunderstorms. There will be a breif dry period
late in the day saturday, as models suggest a dry slot pushes into
the Northland. However, the break will be short lived as the cold
front sweeps across the region, triggering another round of
showers and thunderstorms Sunday.
The rain chances will remain in the forecast into next week as a
slow moving upper level low tracks across northern minnesota. The
GFS bufr soundings show steep lapse rates associated with the low
as 850 hPa temps fall into the single digits. Although timing
differs with the gfs showing the slower trend, long range model
suggest high pressure builds into the region for the later half of
the week.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 639 AM CDT Thu Sep 22 2016
Low clouds and areas of drizzle will be common at Kbrd, kdlh and
Khyr this morning. Conditions are expected to IMPROVE to vfr
through the afternoon...then return to mvfr overnight as
precipitation spreads northward back into the forecast area. The
KINL terminal is expected to remain in the drier air
today...remaining vfr through the taf period. The lowest
conditiionswill be found at KBRD and KHYR.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 63 49 61 52 / 10 10 10 50
INL 64 42 65 50 / 0 0 0 50
BRD 67 52 64 56 / 10 10 20 40
HYR 64 52 64 54 / 30 10 10 40
ASX 62 51 63 52 / 20 10 0 40
&&
.DLH Watches/Warnings/Advisories...
WI...Beach Hazards Statement through this evening for WIZ001.
MN...Beach Hazards Statement through this evening for MNZ037.
LS...Small Craft Advisory until midnight CDT Friday night for LSZ121-
141>148.
&&
$$
SHORT TERM...Grochocinski
LONG TERM...Graning
AVIATION...Graning
Area Forecast Discussion
National Weather Service Goodland KS
542 AM MDT THU SEP 22 2016
.SHORT TERM...(Today through Saturday night)
Issued at 300 AM MDT Thu Sep 22 2016
Early morning RAP and satellite analysis show a large scale
trough over the western US, with a closed center near the
California/Oregon border. Ridging extends across the central US
into the Northern Rockies, with SW flow over the intermountain West.
Today-Tonight: A quasi-stationary front will remain either over the
northern part of our CWA or just north of our CWA complicating temp
forecast. WAA south of this feature should support highs in the 90s,
while north highs may struggle to reach the low 80s (depending on
cloud cover). Precip chances are minimal due to storm track to our
west, and a very dry/stable in place over much of our CWA. There is
a weak precip signal in high resolution guidance in our west
associated with elevated instability above dry adiabatic layer. A
few thunderstorms may develop and attempt to track northeast late
this afternoon and evening with steepening lapse rates near the
surface trough along the CO border ahead of front, but confidence
is low. I introduced slight chances in eastern CO for now.
Friday-Friday night: Large scale forcing increases with entrance
region of jet ahead of large scale trough transitioning over our
CWA. Dry line develops near the CO border and could act as focus for
possible thunderstorm development early in the afternoon Friday
before main period of forcing occurs Friday evening. Biggest question
is going to be low level moisture along/east of this trough and
impact on instability. NAM currently shows ML CAPE around 1500 J/KG
which could be sufficient for an elevated risk of severe
thunderstorms considering the very high shear values ahead of trough
(50kt+ effective shear values). Based on soundings if favorable CAPE
materializes we may see potential for thunderstorms to merge in a
cluster or squall line with a potential for a widespread severe wind
event. Severe hail may be a secondary threat at this point, unless
we see better CAPE profiles than currently advertised.
Other forecast issue of concern Friday would be potential for near
critical fire weather conditions in eastern Colorado as windy
conditions are expected (gusts 40-45 mph possible). There is enough
spread on Tds between models but good mixing may support RH values
dropping below 20 percent in our west (behind dry line). Will need
to monitor.
Saturday-Saturday night: Post frontal air mass with subsidence
building from the northwest should preclude precip chances in all
but our far east/southeast. Expect temperatures to return to near
seasonal normals (highs around 80 and lows in the 40s to the lower
50s).
.LONG TERM...(Sunday through Wednesday)
Issued at 227 AM MDT Thu Sep 22 2016
The long term period is looking to be dry for the entire period.
Yet, there are some major discrepancies between the GFS and EC. The
current model run for the GFS has an exiting deep trough impacting
the region through Tuesday night with a ridge building in behind it.
The EC is much different, with the bulk of that trough moving out of
the region Sunday and then developing a closed low off the trough
over the southwestern states. That closed low is embedded under a
ridge that is over the region. So as far as the models go, there is
little confidence in which one will hold true at this point. One
thing to mention is that Sunday and Monday nights could potentially
see temperatures drop into the mid to upper 30s in some locations.
Will keep an eye on this due to the possibility for a frost
advisory. Otherwise, high temperatures are expected to be in the 60s
and 70s through the entire period, which is about average or just
under for this time of year.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 542 AM MDT Thu Sep 22 2016
Low stratus (already at KMCK) will continue to spread south
towards KGLD, and fog should eventually spread towards both
terminals. IFR CIGS are likely through about 16Z and IFR vis will
be possible. Conditions should improve by late morning. A few high
based showers or thunderstorms will be possible in the
afternoon/evening mainly in eastern Colorado, and confidence is
low that this activity would reach the vicinity of either KGLD or
KMCK. Winds should shift to the south and increase around 00Z with
low level wind shear likely at KMCK after 09Z.
&&
.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...CLT
AVIATION...DR
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1024 AM EDT Thu Sep 22 2016
.SYNOPSIS...
A weak area of low pressure lingering along the coast of the
Carolinas today will drift east on Friday. A broad upper ridge and
surface high pressure will build over the region during the weekend
as temperatures rise well above normal again.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1020 AM EDT Thursday: Not much change needed/made to the
fcst with this update as the region remains under the influence
of the weak stacked low pressure system along the Carolina coast.
As a result, moisture wrapping around the cyclonic flow continues
to advect across the NC/SC piedmont leading to light dz/ra as
well as low stratus. Thus, made a few tweaks to sky accounting
for current stratus placement per visible sat, as well as a few
adjustments to recent temperature trends. Did blend in the latest
campop for pops, which didn`t really yield any sig changes.
Previous Discussion: Still dealing with the effects of easterly
flow around sfc/upper low over the Carolina coast. Pockets of
light showers continue to spin across the Triad and into the NW
Piedmont. Based on the consensus of recent HRRR runs, they may be
able to push as far west as the Hwy 221 corridor by mid-morning. A
thicker and lower cloud deck will also move in this morning, and
guidance mostly indicates that will hang around well into the
afternoon. Max temps are impacted, being just a couple degrees
above normal across most of the area--the upper Savannah valley is
expected to remain sunnier and still reach the upper 80s in spots.
While some pockets of light stratiform rain will move through
the Piedmont at times today, convection is expected to be a bit
less isolated/infrequent than yesterday, on account of slightly
improved lapse rates. Meso models depict isolated convection over
the Blue Ridge and parts of the lower Piedmont, similar to what
verified yesterday, though with a little more QPF. Thunder is still
too unlikely to mention. The low wobbles slightly northeast along
the coast tonight, keeping the low level pattern pretty much the
same. 06z models trended cloudier for tonight, so with this update
I raised sky cover a bit, but still think there will be a decent
gradient across the area. Min temps will be around 10 degrees
above normal.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
As of 230 AM EDT Thursday...still expecting the weekend to be
relatively benign weather-wise...although quite warm. The model
guidance continues to show the old upper low opening up and filling
along the Carolina coast on Friday, although at least some remnant
of the upper system appears to be left to drift westward along the
Gulf Coast, underneath the upper ridge, on Saturday. Whether or not
this feature is the actual upper low should be immaterial, as the
western Carolinas come under the influence of the amplifying upper
ridge from Friday thru Saturday. The plume of wrap-around moisture
might be sufficient to maintain a few showers over the eastern zones
early in the day on Friday, but this will get pushed off to the east
in the afternoon. Some instability over the SW mountains of NC might
allow for a few showers over the higher terrain in the afternoon.
Otherwise, expect most locations to remain dry with high temps
climbing five degrees or so warmer than Thursday, back to almost
Summer-like heat. That trend will continue into Saturday with only a
few ridge-top showers able to break through a strong cap. High temps
should be well above normal...and very much like summer. Uncertainty
begins to creep in from the east on Sunday with some indication that
surface high pressure moving across the Gt Lakes will impose an
easterly flow that will bring some Atlantic moisture over the
region. Fcst soundings from the GFS show the low level moisture
allowing for more sfc-based buoyancy...enough to warrant a chance of
precip over the mtns and foothills by afternoon. This seems
reasonable enough to keep a small chance in the fcst. Temps may be
held in check by increased cloud cover Sunday afternoon, at least
over the NC part of the fcst area.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
As of 315 AM Thursday...you would find it difficult to remember a
time in your recent memory when the operational runs of the medium
range models had less run-to-run continuity and less agreement with
the upper pattern as you see by the middle of next week. Whether the
pattern will remain progressive or amplified or become blocked is
difficult to determine right now, leading to much greater
uncertainty than usual for this time of year. There is at least some
agreement that at some point a frontal boundary will get strung out
close to the fcst area in the middle or late part of the week, so
there is hope of getting some much-needed rain. Details are very
sketchy though. At this point, prefer to not make any changes in the
medium range and will look toward hopefully seeing some consistency
and/or trend in the next model cycle.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
At KCLT: Low pressure over the eastern Carolinas will sustain a
breezy northeasterly flow over the field thru the period. MVFR
stratus will expand westward thru central NC in the first few hrs
of the period, along with bands of light showers. Can`t absolutely
rule out IFR early on, but it is unlikely given how slowly it
advanced in the predawn hours. The moist layer is deep enough that
daytime improvement will be much slower than usual. Lapse rates
are a tad more favorable than those Wed, so a few SHRA may be
around during the afternoon; chance is too low to mention at this
issuance. Tonight, with the pattern having changed very little,
MVFR cigs again are likely to expand over the field after midnight.
Elsewhere: MVFR cigs are expected to expand as far west as KHKY/KGSP
before that deck begins to dissipate. Abundant low VFR cloud is
expected to hang around into afternoon, however. Some sprinkles
are possible in the morning as bands of better forcing round the
low. Also, once cigs finally lift and/or scatter a bit, a few
diurnally driven SHRA may develop, though still too isolated to
mention in TAFs. Winds mainly NE thru the period, with some low-end
gusts in the middle of the day. MVFR cigs are expected to advect
in from the east again overnight tonight, similar to how they did
so early today. Profiles look a bit more favorable for valley fog,
too, so a vsby restriction is introduced at KAVL.
Outlook: Meandering low pressure along the Carolina coast will
persist thru Friday. This will allow isolated to scattered diurnal
convection to continue especially east of I-77, and periodic
chances for restrictive cigs. Meanwhile, a new cold front will be
approaching from the northeast Sunday, but with sparse precipitation
expected at this point.
Confidence Table...
14-20Z 20-02Z 02-08Z 08-12Z
KCLT High 96% High 94% High 100% High 97%
KGSP High 87% High 100% High 100% High 100%
KAVL High 100% High 100% High 100% Med 77%
KHKY High 98% High 100% High 100% Med 71%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...PM
NEAR TERM...CDG/Wimberley
SHORT TERM...PM
LONG TERM...PM
AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Melbourne FL
950 AM EDT THU SEP 22 2016
.UPDATE...
Surface/satellite observations continue to indicate a broad and
diffuse surface trough extending from a weak low pressure area and
its attendant frontal boundary along the GA/SC/NC coast to just east
of central Florida. Water vapor and RAP analysis fields show the mid
and upper level trough near and west of this feature elongating to
the SW due to deformation being imposed by strong ridges to its west
and east.
Morning RAOB data shows local air mass has dried out a little, with
mean PWATs in the 1.7"/1.8" range at JAX/TBW/XMR and around 1.9" at
MFL. H50 temps are averaging a tepid -6C. Both the RAOBs and CCAFS
915MHZ DRWP data show very light SW flow throughout the column,
averaging about 6-8KT, except for a small layer of 11-14KT winds
between H80 and H50. Setup of weak steering and seasonable PWAT
values portends a rather nondescript convective day, with local sea,
lake and t-storm outflow boundaries dominant. Lightning and ponding
from locally heavy downpours the main concerns with todays storms.
Maybe a slightly better chance for storms down near Lake Okeechobee
owing to slightly higher PWAT and sea/lake breeze interaction. See
no compelling reason to adjust the inherited forecast of 20-30 pct.
&&
.AVIATION...VFR to start, with ISOLD-SCT diurnal SHRA/TS increasing
in coverage starting about 17Z-18Z. for better or worse, tweaked the
12Z TAFs to confine VCTS south of LEE-SFB-DAB. POPs in the 20-30 pct
range didn`t warrant TEMPO groups, however best chance for TS INVOF
MLB-SUA corridor looks to be 17-21Z, and 20Z-24Z for ISM-MCO VCNTY.
&&
.MARINE...Light offshore component to wind flow will yield to diurnal
sea breeze circulation during the afternoon, with a small chance for
offshore moving storms late in the day, mainly near the coast. Seas
1.5 - 2.0FT near shore and 2.0 - 2.5FT well offshore. Given current
conditions, plan to shave about half a foot from the grids.
&&
FORECAST UPDATE...Cristaldi
IMPACT WX/RADAR...Glitto
&&
.PREV DISCUSSION... /issued 335 AM EDT Thu Sep 22 2016/
Fri-Fri night...Weakening shortwave troughing along the eastern
seaboard continues to do so over this period. In turn, shortwave
ridging amplifies from the northwest Gulf through the Eastern Plains
and Upper Midwest. At the surface, weak high pressure encompasses
much of the Gulf Coast States with a very weak pressure gradient
across ECFL. Light/variable morning winds will become onshore in the
afternoon as the east coast sea breeze develops and pushes slowly
inland. Greater deep layer moisture will be confined to the Treasure
Coast (PWAT greater than 2 inches), while PWAT values to the north
across the I-4 corridor will flirt with only 1.50 inches. Will keep
30 percent POPs across the I-4 corridor, which may be generous, and
40 to 50 percent POPs southward toward the Treasure Coast. The storm
steering flow will remain fairly light at 5 to 10 mph out of the
southwest. A few afternoon/early evening storms may move off of the
east coast south from the Cape.
Winds will become light/variable again in the evening/overnight.
Highs in the U80s to near 90 degrees near the east coast and
generally L90s into the interior. Overnight conditions remain
warm/humid with lows in the L-M70s.
Sat-Wed...Shortwave ridging aloft remains forecast to build across
the eastern CONUS this weekend, continuing to amplify to the east of
the Ohio/Tennessee Valleys Mon-Tue, then getting nudged off of the
Atlantic seaboard Tue night/Wed as a fairly strong upper-level
trough plows through much of the central CONUS and upper Midwest.
The pressure gradient will remain very weak with light/variable
winds overnight/early morning becoming onshore each afternoon as the
east coast sea breeze develops and pushes inland. Deep layer
moisture values increase areawide through the period, promoting 40
to 50 percent chances of afternoon and early evening showers/storms.
Storm motion will remain out of the west or southwest, albeit light,
into Mon then will become easterly Tue/Wed as onshore flow deepens
over the area. Main storm threats will remain heavy downpours,
lightning, and some brief gusty winds.
Expect some long period swells to impact the east coast beaches and
possibly bringing a higher rip current risk by Friday and into the
weekend. Highs/lows near to slightly above normal through the
extended.
&&
.AVIATION...Lingering isolated showers/storms produced local IFR-
MVFR during the overnight from KMLB-KSUA, but a diminishing trend
is underway and most terminals will be VFR this morning. The
highest chance for afternoon/evening storms looks to be southward
from KMCO-KTIX.
&&
.MARINE...
Today-Tonight...Generally favorable boating conditions continuing,
though mariners will need to keep aware of isolated to scattered
showers/storms that form over land this afternoon/evening and push
slowly back to the coast.
Otherwise, a weak pressure gradient in place will yield
light/variable morning winds, which become onshore by early
afternoon as the sea breeze forms. Light winds again in the evening,
gradually becoming offshore after midnight. The Wave Watch model
looks slightly better than the local wave model, though seas
will be rather benign with swells 2 feet nearshore and 3 feet
offshore.
Fri-Mon...A weak pressure gradient will continue over the local
coastal waters promoting a gentle to light breeze. TC Karl will re-
curve away from the area, sending a small-moderate swell into the
local waters. Seas generally 2-3FT near shore and 4FT (or a little
higher) over the open Atlantic, decreasing by Monday as the local
swell generated by Karl decays. Isolated to scattered lightning
storms will continue in the forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 88 73 88 72 / 20 20 30 20
MCO 91 74 92 73 / 30 20 30 20
MLB 89 75 90 74 / 40 30 30 30
VRB 89 75 89 72 / 40 30 40 30
LEE 91 74 91 74 / 20 20 30 20
SFB 91 74 91 74 / 20 20 30 20
ORL 91 75 92 75 / 30 20 30 20
FPR 90 74 90 72 / 40 30 40 30
&&
.MLB Watches/Warnings/Advisories...
FL...None.
AM...None.
&&
$$
Area Forecast Discussion
National Weather Service Mobile AL
651 AM CDT THU SEP 22 2016
.DISCUSSION...Updated for latest aviation discussion below.
&&
.AVIATION...
22/12Z issuance...VFR conditions will continue through the forecast
period. Some isolated showers or storms from Mobile Bay area northward
and westward this afternoon with brief periods of MVFR possible...but
overall coverage is expected to be very sparse and only included
VCTS at terminals. Surface winds light and variable for most
locations...with brief period of more predominant southeast winds
near the coast this afternoon. 12/DS
&&
.PREV DISCUSSION... /issued 445 AM CDT THU SEP 22 2016/
NEAR TERM /Now Through Thursday night/...Surface high pressure ridge
that has been over the region builds slightly today and tonight,
resulting in a generally light and variable wind flow across the
region (although becoming predominately southwesterly near shore late
this afternoon with daytime heating developing a weak sea breeze
circulation). In the upper levels 500mb low over the Carolina`s early
this morning will likely open into a trof by tonight...with upper
high pressure noted just to the west of the fcst area over eastern
Texas and Louisiana. Models indicate that the resultant north to
northeast flow aloft may allow weak shortwave energy to move south
over or near western portions of fcst area today. With this...we
could see some isolated afternoon showers or storms over the western
zones (primarily from Mobile/Baldwin counties and points northward
and westward). ECMWF advertises essentially no PoP today...while GFS
shows very isolated. Even Hi-Res HRRR indicates very isolated
coverages...so opted to not include a rain chance for today(although
a very isolated shower or storm could be possible over the western
zones as mentioned above). Expect temperatures to again heat up into
the lower 90s over interior locations today (which is nearly 10
degrees above normal) and upper 80s to near 90 at the coast (also
above normal...by 6-8 degrees for those locations). Low temperatures
tonight expected to be above normal as well (by 5 to 10 degrees or
so) ranging from upper 60s to near 70s inland to low to mid 70s at
the coast. 12/DS
SHORT TERM /Friday Through Saturday night/...Several strong
shortwaves swing slowly east over the western Conus to the Rockies,
with a piece breaking off an forming a closed low over the Desert
Southwest. More energy organizes into a deep upper low over the
Canadian Maritimes through the same period, and in combination with
the western trough, builds a strong upper ridge over the Mississippi
River Valley. The opening upper system over the Carolina coast
continues to weaken into a weak shortwave system, but remains strong
enough to create a surface circulation strong enough to disrupt a
surface ridge stretching south along the Appalachians into Saturday
night.
For the forecast, subsidence from the building upper trough will
continue to keep temperatures will above seasonal levels (low to mid
90s for highs, upper 60s to low 70s for lows). With the surface ridge
disrupted by a weak surface low/circulation, a diurnally driven
daytime Gulf breeze/ night-time land breeze setup will create a few
offshore shra/tsra, which will move inland with the Gulf breeze. As
the Gulf breeze brings increasing moisture inland, am expecting
precip chances to slowly creep up into the weekend.
/16
LONG TERM /Sunday Through Wednesday/...The extended continues to be a
bear, with inconsistency between models and temporal inconsistencies.
The latest medium range model runs are consistent in advertising a
piece of energy breaking off the southern end the western upper
trough, but the handling of the northern end is the where the
problems lies. The GFS in now advertising the western trough working
with the southward shifting Canadian upper low to build an upper
trough over the Eastern Seaboard (like the ECMWF was advertising
yesterday), whilst todays ECMWF run is advertising the northern piece
of energy moving east over the Northern Plains/Great lakes region to
the Mid Atlantic region. Even with the ECMWF advertising a flattening
of the upper ridge, it is keeping it strong enough to advertise a
warmer solution than the GFS. The difference is closer than
yesterday, but is still significant enough to keep from saying they
are in general agreement. Both are advertising a weak surface front
being pushed towards the fa (from the nw by the GFS, from the n by
the ECMWF), then stalling it close (ECMWF) or over (GFS) the fa by
Wednesday evening. The GFS is also advertising a wetter solution then
ECMWF, with the boundary stalled over the fa. Have went with a
blended approach for the forecast, with temps remaining well above
seasonal levels and chance of rain a bit above seasonal.
/16
MARINE...A high pressure ridge will persist over and just north of
the coastal waters through them remainder of the week and into the
early part of next week. Winds will remain light (generally 10 knots
or less) and sea states will remain small (occasionally 1 to 2 feet
at the most...generally 1 foot or less). Only isolated to ocnly
scattered showers and storms over the marine area. 12/DS
&&
.MOB Watches/Warnings/Advisories...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Phoenix AZ
618 AM MST THU SEP 22 2016
.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS.
&&
.SYNOPSIS...
Showers and a few thunderstorms will be possible today along and
ahead of a cold front moving through the region. This front will
bring gusty winds, drier air, and slightly cooler temperatures for
the remainder of the week. Breezy, but otherwise quiet weather will
be the rule for the weekend and into early next week along with a
warming trend.
&&
.DISCUSSION...
Impressive and unseasonably cool upper low continued to take shape
along the northern California and Pacific NW coast early this
morning, and latest guidance is consistent in calling for this low
to progressively dive to the southeast today and push into the
desert southwest bringing scattered to numerous showers along with
embedded thunderstorms to the lower deserts during the day today.
Ample moisture is already in place across the lower deserts; surface
dewpoints at 2 am were mostly in the mid to upper 60s with values as
high as low 70s across portions of the lower Colorado River valley.
IR imagery showed variable amounts of low to mid cloud over the
western AZ and southeast CA deserts although current radar showed
little in terms of shower activity. Through about sunrise, QG
forcing is not especially strong and local models do not really show
much convection developing until around 12z or so this morning.
As the main upper low center drops into central Nevada this
afternoon, a well defined frontal band oriented mostly north to
south will push across the western AZ deserts and into south central
arizona; some of the best QG forcing/Q convergence fields move into
the central deserts this afternoon and the associated UVV will act
on a very moist airmass to generate widespread showers with embedded
thunderstorm. Latest HRRR depicts this scenario very nicely and our
forecast timing of the front will mirror the HRRR timing. POPs have
been raised into the 50-60 percent ballpark across much of the
central deserts with the best chances for rainfall in the greater
Phoenix area to occur during the afternoon today. These higher POPs
are supported by the latest NAEFS POPs guidance.
Gusty west winds are expected to develop over the western deserts
this afternoon behind the front, with the strongest winds likely to
occur over favored areas of Imperial county; peak gusts to 35 mph
are likely. There may be some patchy blowing dust occurring due to
the wind, but recent rains in the area will limit the potential for
any significant dust and as such we will not mention blowing dust in
our forecast grids at this time. As far as temperatures go today,
with thickness values lowering to around 576dm and with considerable
lower clouds and showers in the area, high temperatures will fall to
well below seasonal normal values with many lower AZ deserts falling
into the upper 80s to low 90s. Phoenix should see a high around 90
today which would be 8 degrees below normal.
Upper low center will quickly move east into Utah tonight and most
of the strong QG forcing will shift well east of Phoenix; as such
POPs tonight will focus across the higher terrain of southern Gila
County with values as high as 40 percent or so. Rain chances will
quickly diminish this evening over the south central deserts; rain
chances in Phoenix will lower to around 10-15 percent after midnight.
On Friday, the main upper low is forecast to quickly lift off to the
northeast but a much drier and more subsident northwest flow aloft
will overspread the deserts. Outside of a lingering slight chance of
showers over southern Gila County we can expect generally sunny
skies over the lower deserts with continued below seasonal normal
high temperatures. PWAT values are forecast to fall to around one
quarter of inch over much of the lower central deserts by Friday
afternoon and the surface dewpoints in the Phoenix area will fall
from the mid to upper 60s today into the upper teens to mid 20s.
Over the weekend and into next week, dry conditions are forecast
area wide with no threat of precipitation. A large upper ridge will
initially amplify along the west coast giving a dry northerly flow
to the area but early next week the ridge will flatten somewhat but
continue giving dry northwest flow into the lower deserts. Expect
generally sunny days and clear nights this weekend into the middle
portion of next week along with a gradually warming trend. High
temperatures will climb into the mid to upper 90s over most of the
lower deserts by the early to middle part of next week.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
A cold front will approach from the west, crossing through the
terminals from mid to late afternoon along with rain showers and
isolated thunderstorms likely beginning about 22Z. Expect low cloud
cigs from 5-6Kft. for most of the day before skies begin to scatter
beginning in the the late afternoon and early evening. Light winds
in the morning should become breezy and southerly by late morning,
and then southwesterly to westerly with gusts of 17-22kts.
beginning in the early afternoon. Westerly winds will begin to taper
off to 7-10 kts. beginning in the early evening.
Southeast California/Southwest Arizona including KIPL and KBLH:
Clear to partly cloudy skies with few to sct low clouds near 6-7
Kft. will become clear by late morning at both sites. Breezy
westerly winds at KIPL will become windy by late morning with gusts
of 21-30kts. Meanwhile windy southwesterly winds will develop at
KBLH by late morning with gusts of 25-28kts.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday...
Very dry northwesterly flow aloft behind a trough to the east on
Saturday will eventually be replaced by a dry ridge of high pressure
on Wednesday along with below normal high temperatures throughout
the period. Breezy to occasionally windy northerly component winds
will prevail out west, especially along the lower Colorado river
valley each afternoon through Monday with gusts of 20 to 28 mph,
although conditions are not expected to reach critical thresholds
at this time. Gusty northeasterly winds will then spread into the
lower deserts and the higher terrain of southern Gila county
beginning Tuesday. Minimum RH of 13 to 20 percent on Saturday will
slowly increase each day until reaching only 20 to 30 percent on
Wednesday. Fair overnight recoveries on Saturday will improve to
fair to good by Tuesday.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter reports may be needed locally Thursday afternoon across the
Phoenix area.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...CB
AVIATION...Sawtelle
FIRE WEATHER...Sawtelle
...Update to aviation forecast discussion...
.SHORT TERM...(Today and tonight)
Issued at 319 AM CDT Thu Sep 22 2016
Current water vapor shows several weak mid level shortwaves moving
out over the plains this morning. The associated weak isentropic
lift is expected between now and late morning mainly over north
central and far northern KS. This is where isolated to scattered
showers and possibly some thunder may occur. The GFS seems quite
bullish with the amount of QPF especially given the fact no other
models agree with these amounts. Also, there is a small complex of
decaying storms over southwest KS. Any remnant MCV could reach north
central KS later this morning and bring a slight chance for showers
as well. Only the HRRR is showing this activity will reach the
forecast area. After late morning the chances should diminish. High
clouds associated with the tropical moisture fetch will stick around
until at least the evening. Highs today look to reach the upper 80s
to lower 90s with dew points in the upper 60s. Winds will become
gusty out of the south again today mainly during the late morning
and early afternoon. Quiet weather continues tonight with partly
cloudy skies and lows in the mid 60s.
.LONG TERM...(Friday through Wednesday)
Issued at 319 AM CDT Thu Sep 22 2016
Friday, the downstream ridge across the plains and mid MS river
valley will amplify as the upper trough across the western US
deepens. Friday will be another warm day with south-southeast winds
of 15 to 25 MPH. Highs will reach the upper 80s to lower 90s.
Thunderstorms that develop across western KS during the early
evening hours may reach the western counties of the CWA late Friday
night.
Saturday through Sunday night, An intense upper level trough across
the Western US on Friday will begin to shear apart as if moves east
across the plains. There will be stronger ascent ahead of the
positive tilt upper wave as it moves east across KS Saturday night
through Sunday night. There will be a good transport of deep gulf
moisture northeast across eastern KS at 850mb, ahead of the upper
trough Saturday night through Sunday. Both the GFS and ECMWF
forecast a widespread QPF of 1 to 3 inches across the CWA. If the
rain falls over a 24 to 36 hour period then there will probably only
be minor flooding possible. However, stronger thunderstorms may
train from southwest to northeast across portions of the CWA
Saturday evening into Sunday morning which may produce a greater
potential for flash flooding. The next few shifts will have to watch
the potential for flooding Saturday night into Sunday.
Since the upper trough begins to shear apart as it moves into the
plains, the 0-6 KM effective shear weakens during the afternoon
hours. Given MLCAPES of 1500-2500 there could be a few pulse severe
storms that develop along the surface front across west central KS,
then may move into the western counties of the CWA before the
stronger ascent moves east along the front and develops a line
of showers and thunderstorms during the evening hours of Sunday.
The GFS is more progressive moving the upper trough east across the
plains and the heavier rain may move southeast of the CWA during
the mid morning hours of Sunday. If the GFS were to verify the
surface front will move southeast across the CWA during the early
morning hours of Sunday and skies may clear from northwest to
southeast during the afternoon hours. The ECMWF is slower moving the
positive tilt H5 trough across the plains on Sunday and keeps
widespread showers and elevated thunderstorms across much of the CWA
through the day Sunday and into Sunday night as isentropic lift
continues north of the surface cold front.
Monday through Tuesday, Once again the ECMWF and GFS solutions
diverge as the ECMWF continues to amplify the southern section of
the upper level trough across southwest NM, then lifts the H5 trough
northeast across the plains by mid week. The GFS keeps the northern
branch of the H5 trough amplified as it shifts northeast across the
Great Lake States. If the ECMWF verifies there will be at least a
slight chances for showers and thunderstorms through the week. If the
GFS were to verify then expect dry conditions through the week.
Highs will be around 70 on Monday with temperatures warning into the
mid to upper 70s by Thursday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 609 AM CDT Thu Sep 22 2016
VFR conditions expected through the taf period.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Sanders
LONG TERM...Gargan
AVIATION...Sanders
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
338 PM CDT Thu Sep 22 2016
.SHORT TERM.../This evening through Friday/
Issued at 307 PM CDT Thu Sep 22 2016
The situation is still conducive for heavy rains tonight but
hopefully not to the same extent as yesterday. Water vapor imagery
does not show the moisture fetch to the same degree as was shown
Wednesday, but there is a decided back edge to the vertical motion
passing through the Plains into western KS/NE which should aid lift
into the night. This has resulted in weak but broad mid level
kinematic forcing with a ribbon of somewhat favorable mid level temp
and theta-e lapse rates from KS into IA. Thermodynamically the
forcing is somewhat better with 850/700mb warm advection noted into
IA and 0-2km moisture pooling into our baroclinic zone as well. 20Z
surface analysis shows at least two boundaries, one tied into low
pressure near Lincoln between Red Oak and Atlantic, another farther
northeast through the Des Moines metro area more associated with
previous MCS outflow and likely another from Estherville to Grinnell
with seems to be immediately associated with the weak MCS. This
will provide for ample isentropic lift into the night, but the flow
is weaker along the 305K inflow surface vs last night, down to 15-
30kts. RAP elevated instability layers suggest elevated CAPEs will
reach uncapped 1500 j/kg later tonight sustaining additional MCS
development. There could be a few strong to severe storms, but
overall the Marginal Risk seems fine due to reduced effective shear.
.LONG TERM.../Friday night through Thursday/
Issued at 307 PM CDT Thu Sep 22 2016
Expecting some early morning ongoing convection across the eastern
and northeastern areas to end by mid to late morning. Warm front
will finally retreat north into the afternoon hours with rather warm
and humid conditions across the area for the remainder of the day.
Some cloud cover extending across the northeast with light showers
then will give way to some sun in the afternoon. As has been
advertised...highs will warm into the upper 80s to lower 90s over
the south with the upper 70s in the far north by late day Friday. No
rainfall is expected until the long wave trough approaches Saturday
morning with showers and thunderstorms moving into Central Iowa by
mid to late afternoon. Remnant tropical moisture from Paine will
probably still be available at this time across our area. With a
ribbon of higher precipitable water and decent convergence along the
boundary...will likely see a decent rain event with up to an inch
additional from Saturday evening through Sunday. Once this feature
pulls east...the models are in some consensus for next week. Both
the Euro and GFS now suggest that the H500 long wave trough will
keep the moisture channel south and east of the region. This should
allow for a period of little to no precipitation and help the river
situation across the area. Temperatures next week look cooler and
more seasonal for the first week of fall.
&&
.AVIATION.../For the 18Z TAFS through 18Z Friday afternoon/
Issued at 139 PM CDT Thu Sep 22 2016
Conditions are generally improving with VFR in most locations and
only a few MVFR spots. Weak convection will also linger in the
KALO area through the afternoon. The question becomes convection
and cig/vsby trends into the night and there is low confidence
again in that regard. Until confidence increases have only
included VFR conditions and vicinity wording rather than prolonged
periods of thunder and/or category degradations.
&&
.HYDROLOGY...
Issued at 307 PM CDT Thu Sep 22 2016
Magnitude and placement of the heavy rains will be key tonight. As
mentioned above the environment is not as favorable as last night
but still supports heave rain. The surface based potential is trying
to recover with uncapped 1500-2500 j/kg MLCAPEs now in place over SW
IA. This recovery may be too late to get anything going, but will
likely aid slightly elevated convection just to the north and east
tonight. The latest objective analysis pegs 0-2km moisture
convergence along the Highway 20 to 30 corridors so this will be the
favored location, likely anchored along or just south of the current
Waterloo MCS which won`t go away. Precipitable waters are already
around 2 with warm cloud depths higher than yesterday to 4km. Thus
the moisture transport and instability components will not be as
good as yesterday, but efficient rains are still anticipated. This
will result in 1 rainfall amounts through the aforementioned
favored corridor with locally higher amounts from 2-3 possible,
thankfully south of where yesterday`s heavy rain occurred. Storms
will not be fast moving with a mean of only 15-20kts and Corfidi
vectors slow to the south. Thus have kept the flash flood watch in
place through 18z Fri and expanded down to the full Highway 30
corridor from Guthrie County eastward. A small section of west
central IA counties has been canceled however, which does not seem
to be under the gun and didn`t receive much rain overnight.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Friday afternoon for IAZ004>007-
015>017-023>028-034>039-046>050.
&&
$$
SHORT TERM...Small
LONG TERM...REV
AVIATION...Small
HYDROLOGY...Small
Area Forecast Discussion
National Weather Service Hastings NE
417 PM CDT THU SEP 22 2016
.SHORT TERM...(This evening through Sunday daytime)
Issued at 417 PM CDT Thu Sep 22 2016
Forecast highlights/overview of these next 72 hours:
The primary concern through these 72 hours centers around the
still-somewhat- unclear rain/thunderstorm chances centered on the
Friday night- Saturday night time frame (rain chances/PoPs have
been held below "likely" 60+ percentages at this time due to
inherent uncertainty in coverage). Assuming that at least
isolated/scattered activity is able to develop during this time
frame, a few strong to severe storms are not out of the question,
especially Saturday afternoon within eastern parts of the CWA.
Turning back to the nearer-term, have left the forecast void of
any mentionable (meaning 15+ percent) shower/storm chances through
tonight, but these chances are not necessarily "zero" either.
There is some concern for at least patchy fog development mainly
within counties along/especially north of I-80 tonight, with a few
higher-res models such as the HRRR suggesting that this fog could
be a bit more widespread/impactful. For now, have not gotten very
aggressive but did at least introduce a mention of "patchy fog
with visibility less than 1 mile" to tonight`s forecast.
Temperature-wise, unlike today, Friday is expected to have a more
uniform temperature regime with well-above normal heat in all
areas. Then, a gradual cool-down should occur over the weekend,
with highs by Sunday actually slightly below normal (and roughly
20 degrees cooler than Friday).
Taking a look at the current scene as of 330 PM (and as outlined
in the "update" discussion earlier this morning)...sky
cover/temperature forecasting has been a bit of an "adventure"
today thanks to a stark division between widespread sun/heat over
southern/eastern counties and a nearly solid deck of low stratus
clouds over many northern/western counties. As expected, the
southern/eastern edges of this low stratus has in fact slowly
retreated/eroded off to the north and west in response to daytime
heating and mixing. Gave a "best shot" at where actual high temps
will end up, but currently it appears a rather big gradient from
low-mid 70s far north/west-central...mid 70s to low 80s in the
central Tri-Cities area...and noticeably hotter upper 80s to low
and even mid-90s in far eastern and southern counties (hottest of
all in our southern-most KS zones). At the surface, the edge of
this stratus is fairly closely tied to the position of a nearly-
stationary front that is draped across the CWA from west-southeast
to east-northeast. Fairly light north/northeast breezes prevail
north of this boundary while southerly breezes prevail to its
south...and a hodge-podge of light/variable in between. In the
mid-upper levels, a period of weak/subtle ridging appears to be in
control of the Central Plains between a departing shortwave over
IA, and a powerful/highly-amplified trough over the western CONUS
featuring a deep closed low centered over NV.
Now looking ahead forecast-wise through these next 6 day/night
forecast periods...
This evening/tonight:
Despite various hints in various models that at least spotty
shower/thunderstorm activity could at least flirt with the fringes
of our CWA (especially northern areas after dark), decided that
the overall coverage of any of this possible activity within our
borders would remain closer to 10 percent than 20 percent, and
thus these chances are below mentionable thresholds (in other
words, the forecast reads as "dry" but please note that chances
are not necessarily zero). Certaintly, the most legitimate
rain/storm chances tonight should focus north of our CWA from
northern NE eastward into IA, where mid level temps are a touch
cooler and where there is better convergence near the nose of a
modest low level jet. At the surface, the aforementioned front
draped across the heart of the CWA will slowly lift northward as
a warm front overnight in response to low pressure deepening to
the west, turning breezes more southerly as it does so. It is
still unclear exactly what the low stratus deck does, as its
northward-retreat is likely to stall out for a time around
nightfall, keeping it stubbornly over our northern/west-central
zones well into the night before eventually vacating our CWA for
good. As mentioned in the opening paragraph, there are hints of
fog development overnight mainly in counties north of the I-80
corridor, and have introduced a generic "patchy with visibility
less than one mile" to get the ball rolling this direction. Temp-
wise, if anything nudged down lows very slightly, aiming for mid-
upper 60s most areas but low 60s far north.
Friday daytime/night:
This is "part 1" of our upcoming rain/storm chances, and
confidence is pretty high that they will not even arrive in
western zones until after dark. In the mid-upper levels, the
aforementioned deep western trough will gradually approach/invade
the Central Plains, with its primary mid level vort max reaching
western WY by late afternoon, and into southeast MT by daybreak
Saturday. Ahead of this system, confidence remains rather high in
a dry, mostly sunny and very warm (some would say hot) day with
noticeably breezy southerly winds overtaking the entire CWA as the
warm front blasts well to our north. Made little change to high
temps/winds, as the entire CWA is expected to top out 88-91 in the
presence of sustained south winds 15-25 MPH and gusts 25-25 MPH,
highest in the afternoon. Then, as the night wears on, forcing
gradually increases from the west, and fairly low chances for
isolated to perhaps scattered of showers/thunderstorms arrive to
the western CWA before midnight and then expand CWA-wide late in
the night. Can`t completely rule out a rogue strong to marginally
severe storm mainly with hail, but this should be the exception.
The invading north-south oriented synoptic cold front may be right
on our western doorstep by night`s end, but ahead of this boundary
low temps should hold up mid-upper 60s most areas.
Saturday daytime/night:
This is "part 2" of the storm chances, but confidence in areal
coverage of this rainfall is still not high enough to justify
"likely" PoPs within the CWA. Certainly though, chances are higher
in southern/eastern counties than they are in northern/western
counties (which could really end up missing out on things). In the
mid-upper levels, the main vort max swings north toward ND during
this time, while the large-scale trough trailing to its south
slowly edges east through the Plains. Meanwhile at the surface,
barring some fairly big changes, models have seemingly settled on
a steady west-to-east progression of the synoptic cold front
through the CWA during this time. Based on instability/shear progs
and the timing of the boundary, especially our eastern-most
counties may see at least a brief severe storm threat Saturday
afternoon along this front, and agree with the SPC putting these
areas in a Marginal Risk. This will bear watching, because if the
front slows at all, then more of our CWA may be in a severe risk
mainly for large hail/wind. Taking the latest models literally
(especially the NAM) suggest that the majority of shower/storm
chances may be over with by sunset. However, models such as the
ECMWF/GFS are slower with precip departure, and thus will linger
modest PoPS through the night especially in eastern/southern
zones. High temps are aimed low 80s most areas and with With
cooler air invading, lows expected to drop into the 50s nearly all
areas.
Sunday daytime:
Although it could be a close call in extreme southeast zones,
confidence was high enough to leave the entire CWA void of
shower/storm chances behind the departing cold front. As a result,
we are looking at a "fallish" day featuring plenty of sunshine,
cooler temps and breezy northwest winds averaging 15-20 MPH with
higher gusts. If anything, nudged up highs 1-2 degrees given
expectation of sun/decent mixing, aiming for 69-72 most areas.
.LONG TERM...(Sunday night through Thursday)
Issued at 417 PM CDT Thu Sep 22 2016
Fall-like conditions are forecast to continue on into the beginning
of the next work week, with temps climbing back to normal by mid-
week.
The main change made to the forecast for the long term was to remove
precipitation chances. At the start of the period, models are in
pretty good agreement showing the main upper level trough axis
continuing to push through/east of the CWA. By 12z Monday, the axis
looks to extend from central MN south through central KS, with
northwesterly winds in place across the CWA. That northwesterly flow
aloft remains in place through at least Mon/Tues, as ridging over
off the west coast starts pushing east through the Rockies. As we
get into Wed/Thurs, that ridging moves onto the Plains/right over
the CWA. The 12Z run of the ECMWF/GFS are in good agreement showing
little in the way of disturbances moving through, keeping this dry.
The 12Z run of the Canadian is an outlier, keeping a massive cut off
lower pressure system over the central CONUS through the period.
At the surface, high pressure builds into the region behind the
weekend frontal passage, with light, northerly winds on Monday
turning more variable for Tuesday. Return southerly flow looks to
return for mid-week. As far as temperatures go, not expecting a lot
of change for Mon/Tues compared to Sun, with highs generally in the
mid-upper 60s and dewpoints in the 30s and 40s. Warmer temps
forecast for mid-week with the upper ridge building in, reaching the
mid 70s by Thursday.
&&
.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Friday afternoon)
Issued at 1237 PM CDT Thu Sep 22 2016
Although confidence is rather high in VFR conditions especially by
the final 6 hours of the period Friday, and confidence is high in
IFR/MVFR ceiling at least during these first 2-4 hours this
afternoon, there is still a fair degree of uncertainty lurking
within the hours in between. Read on for more element-specific
details...
Ceiling/visibility:
Needless to say, ceiling trends have gotten considerably more
pessimistic since the last routine 12z issuance, especially for
these first 12 hours. A low stratus deck (currently IFR) has moved
southward into the area, and although confidence is high that it
will persist at KGRI/KEAR for at least a few more hours, already
by late this afternoon there are some models/guidance that try
scattering it out while others hold firm at MVFR levels. For now,
will side with the more pessimistic side of solutions and maintain
MVFR well into tonight before bringing back VFR by around 07z as
this low cloud deck is expected to finally retreat northward by
then (if it hasn`t already), with VFR thereafter. As for
visibility, cannot rule out at least some light fog overnight, but
for now have kept visibility low-end VFR and only "hinted" at
possible fog with a "6SM BR" mention.
Surface wind and low level wind shear (LLWS):
At the surface, winds will undergo some noticeable changes during
the period. Starting off this afternoon/evening, a fairly light
north/northeast breeze will prevail just to the north of a nearly
stationary front. Then, during the latter half of the period, and
especially during the final 6 hours, a switch to a more pronounced
southerly wind will take hold as this front surges northward. By
the last few hours of the period around mid-day Friday, gusts of
at least 20-25kt should be common. Meanwhile, accounting for
increasing southerly winds just above the surface tonight, have
introduced a period of fairly marginal LLWS from 07z-14z as the
magnitude of shear between the surface and roughly 1000 ft should
average around 30kt during this time frame.
Precipitation/thunderstorm chances:
Although there is a very small, non-zero chance of a passing
shower/weak thunderstorm mainly tonight, this chance is certainly
too low for formal TAF inclusion.
&&
.GID Watches/Warnings/Advisories...
NE...None.
KS...None.
&&
$$
SHORT TERM...Pfannkuch
LONG TERM...ADP
AVIATION...Pfannkuch
Forecast discussion for routine afternoon forecast issuance
.SYNOPSIS...
Issued at 223 PM CDT Thu Sep 22 2016
A break in the excessively wet weather, but temperatures remaining
near or above seasonal normals.
Currently on the large scale, strong Pacific jet splits near the
West Coast before merging back together in the Great Lakes region.
The pattern will be slowly progressive, especially early in the
forecast period. Ridging building northeast from the eastern
Pacific will force the location of the split eastward into the
Plains by the weekend. Thereafter, the evolution of the flow
regime becomes uncertain as the medium range models offer varying
ideas on the handling of the remnants of the current southern
stream upper trough. That uncertainty will impact precipitation
chances during the latter part of the forecast period.
Temperatures are expected to remain near to modestly above
seasonal normals through most of the the period, though they could
tail off late. Shower chances will continue the next couple days,
especially across the southern part of the forecast area. But
rainfall amounts should remain on the light side. Precipitation
chances during the middle to latter part of the period will depend
on the evolution of the current southern stream upper trough now
over the western CONUS, and thus are a low-confidence aspect of
the forecast. The best estimate is that rainfall totals for the
next 7 days will end up AOA normal, though at this point amounts
do not look excessive.
&&
.SHORT TERM...Tonight and Friday
Issued at 223 PM CDT Thu Sep 22 2016
The latest RAP analysis and satellite/radar imagery show a nearly
stationary surface cold front stretching from west-central WI to
near Wausaukee early this afternoon. Scattered morning showers died
off along the boundary by midday, but the hi-res models continue to
indicate that a few showers will be possible over east-central and
far northeast WI and within a pwat axis through the rest of the
afternoon. Not convinced that will occur since there is little to no
instability, but left a small chance just in case. Observations
also indicate the presence of some drizzle over far northwest
Wisconsin within a band of low clouds behind the front. Some of
this drizzle could move into Vilas county later this afternoon. As
the front finally makes a move southward tonight, small precip
chances and cloud cover are the main forecast concerns.
Tonight...The cold front will finally move south across central and
northeast WI this evening, and into southern WI overnight. Position
of the pwat axis and hi-res models indicate that east-central WI
could see a shower or two early in the evening before the front
exits the forecast area. But will leave a slight chance across the
south in case the front is slower to exit than progged. Otherwise,
should see widespread cloudiness linger behind the front per
satellite imagery. A developing northeast breeze should keep the
boundary layer churned up to limit fog potential even after all of
the rainfall. Lows falling to near 50 in the north to near 60 in
the south.
Friday...The cold front will settle over far southwest Wisconsin and
northern Illinois. A band of low clouds are expected to remain
behind the front, which should keep central and east-central WI more
cloudy than over northern WI, where northeast winds will push in
drier air. Cannot rule out a few showers over central and east-
central WI in a region of modest mid-level fgen. Because of more
sunshine, northern WI could be as warm or warmer than locations
further south. Will go with highs mostly in the mid 60s.
.LONG TERM...Friday Night Through Thursday
Issued at 223 PM CDT Thu Sep 22 2016
Weak isentropic lift will begin spreading back across the area
Friday night. That seems worthy of having chance PoPs expand
northeast across most of the area during the night, though with
limited instability opted to leave thunder out of the forecast.
Though confidence in precipitation forecast for the rest of the
period is probably lower than normal, leaned toward the ECMWF for
PoPs. The 12Z EC was fairly consistent with its previous run, and
exhibited decent consistency with the GFS ensemble mean. That
resulted in a prolonged period of chance PoPs as the upper trough
crosses the area. The best chance for rain looks to be Sunday and
Sunday night, though that could easily chance in later forecasts.
No significant changes were necessary to the extended forecast
initialization grids based on a broad blend of guidance products.
&&
.AVIATION...for 18Z TAF Issuance
Issued at 1155 AM CDT Thu Sep 22 2016
A nearly stationary frontal boundary extending from west to east
over northern WI will slowly sag south tonight. Some spotty light
showers may still impact the Fox Valley and lakeshore areas for the
rest of the afternoon into tonight, but not expecting much impact to
the flight categories. Plenty of uncertainty in regards to ceilings
behind the front tonight. Guidance is all over the map, but based
on the widespread ifr cigs right behind the front, expect ifr/mvfr
cigs to spread southward late this evening and overnight. Since
will have a NE wind, think fog potential/low vsbys is less of a
concern, especially over eastern WI. Ceilings then should improve
my late morning on Friday.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....MPC
LONG TERM......Skowronski
AVIATION.......MPC
Area Forecast Discussion
National Weather Service Wilmington NC
640 PM EDT Thu Sep 22 2016
.SYNOPSIS...
Weakening low pressure will drift offshore of the Carolinas
through late Friday, taking the rainfall threat with it.
Weak high pressure accompanied by drier air will prevail on
Saturday. A modest cold front will drop south across the area
early Sunday. Modest high pressure will follow and ridge across
the area from the NE states through the early to mid week period
of next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 600 PM Thursday...POPs have been increased thruout this
evening with the going concern being the continued moderate to
heavy rain being produced by the convection. Lightning data has
been limited/sparse across the Carolinas and therefore will just
mention isolated thunder thru mid-evening. With the moderate to
heavy rain persisting well into this evening, unlike what the
latest HRRR and RAP indicate, have updated the pcpn phraseology to
include "heavy rain". In addition, with a half a dozen of Flood
Advisories issued, have updated the Hazardous Weather Outlook to
include the potential for temporary ponding or shallow flooding
from this evenings local heavy rains.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Low pressure over the Cape Fear area will
weaken and move east through Friday as high pressure builds down
from the north. The main mid to upper trough will lift off to the
north and east and a ridge builds over the southeast, although both
the ECMWF and the GFS show a low cutting off from the main trough
and lingering across the deep south into Sun. A weak backdoor
front will make its way south through VA and into NC Sat night and
should reach into SC by Sun morning. Pcp water values up close to
1.9 inches on Fri mainly aligned along the SC/NC coast will
diminish to less than 1.5 inches by Sat aftn with drier air and
subsidence finally scouring out the remaining moisture from this
persistent remnant low from Julia. Therefore, will continue with
higher pops and greatest chc of shwrs/tstms on Fri mainly east of
I-95 to the coast as sfc low remains just off the tip of Cape
Fear. Expect clearing to occur through late Fri into Sat as Dry
air and subsidence work there way south and east as upper ridge
builds east through Saturday. This should produce plenty of
sunshine across much of the area, but lingering moisture along the
coast should produce some cu and possibly some isolated showers
mainly over the SC coast Sat aftn. Not expecting much change in
the feel of the air mass with humid weather continuing. Clouds
will be tough to break on Fri with continued showers and therefore
expect high to be in the 70s much of the day, but places that
break out in the afternoon should reach into the 80s. Saturday will
warm well into the 80s with a good deal of sunshine across much of
the area. Overnight lows will be in the mid 60s to around 70.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 300 AM Thursday...A mid-and-upper level ridge axis will
shift from the TN valley Sunday to the east coast by Tuesday, and
will amplify between two anomalously strong upper lows into a
Omega block-type pattern. At the surface, high pressure will
ridge down across the mid-Atlantic states and produce onshore
flow through the period. Although the primary belts of deepest
moisture will remain south and west of the area, persistent
onshore flow below 850 mb would provide sufficient moisture to
support scattered showers.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 18Z...Expect at least tempo mvfr conditions into the evening
hours in scattered showers and thunderstorms. conditions are
expected to deteriorate to ifr levels again tonight with a slow
transition after sunrise to vfr or mvfr conditions. light, mainly
northeast to east winds are expected through the taf period.
EXTENDED OUTLOOK...Isolated to scattered convection, mainly during
the afternoon and evening hours is possible beneath the cutoff upper
low through Friday. MVFR/IFR morning stratus/fog possible each day
through Saturday. Expect mainly VFR Sunday through Tuesday.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 600 PM Thursday...A relatively relaxed sfc pg will yield 10
kt or less wind speeds tonight. The progged sfc pressure field
itself paints the elongated sfc low, underneath the upper low,
straddling the coasts of NC and SC thru tonight. Could go variable
in direction especially with speeds only at 5 to 10 kt, but
instead will identify the more predominate directions, southeast
to south. Significant seas will primarily be driven by a 1.5 to
2.5 foot, e to ese ground swell from distant Tropical Cyclone
Karl. Latest Spectral Density Chart for 41013 indicates the ese
11-13 second period Karl swell is definitely driving the
significant seas.
Have increased the convection coverage this evening based on
latest KLTX 88D trends. In addition, have highlighted the
persistent convection over the northern-most waters oriented
parallel to Cape Fear, as it pushes northward and onshore.
Waterspout(s) has/have been sighted earlier today in the vicinity
of this pcpn. Will mention this waterspout risk until sunset in
the Hazardous Weather Outlook.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Low pressure just off the tip of Cape
Fear will finally move away as high pressure builds down behind
through Saturday. A cold front will drop south reaching NC Sat
night and should move through the waters by Sun morning. This may
be fairly transparent as winds will have already shifted to the
N-NE by late Fri as low weakens and shifts east. Therefore light
and variable winds on Fri will become northerly by early Sat and
will remain N to NE through Sat night increasing up to 15 kts.
Seas 3 ft or less will increase up to 2 to 4 ft into Sat night. A
longer period SE-E swell will continue through the weekend, up to
11 to 12 seconds.
LONG TERM /SUNDAY THROUGH MONDAY/...
As of 300 AM Thursday...Surface high pressure will build down the
eastern seaboard behind a cold front, which should be crossing
the waters during the day Sunday. With a blocked upper-level
pattern developing through the first of the week, the surface high
will persist and result in onshore flow through Monday. It does
still appear that 3-4 foot swells every 10 seconds will continue
into Sunday from distant tropical system Karl, falling off to a
2-3 foot wind wave by Monday.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH
SHORT TERM...RGZ
LONG TERM...CRM/RGZ
AVIATION...SGL
Area Forecast Discussion
National Weather Service Lincoln IL
300 PM CDT THU SEP 22 2016
.SHORT TERM...(This evening through Friday)
ISSUED AT 259 PM CDT Thu Sep 22 2016
Unseasonably warm conditions will continue in the short term as
upper level ridging holds over much of the Midwest and a nearly
stationary front remains from eastern Nebraska across central Iowa
into southern WI.
Spotty showers across southeast Iowa this afternoon are trying to
work their way into northwest IL, but plenty of mid-level dry air
should result in rapid dissipation. Wouldn`t be surprised to see a
few sprinkles make it through toward Galesburg early this evening,
but not enough for measurable rainfall. Only the GFS and SREF are
allowing for light rainfall overnight, with the other models
continuing dry weather for us and keeping the focus on waterlogged
areas of NE Iowa and SW Wisconsin overnight.
The upper level ridge is expected to strengthen a bit over us on
Friday which will keep the synoptic front to our north. This will
result in another very warm day with highs around 90 in much of
central IL. The exception will be in areas roughly north of I-74
where a few more clouds will keep temps in the mid 80s. With the
front to our north and only a light south wind/very weak convergence
will keep the rain chances out of the forecast through Friday.
&&
.LONG TERM...(Friday night through Thursday)
ISSUED AT 259 PM CDT Thu Sep 22 2016
The 12z models have kept a similar solution for Friday night
through Sunday, with warm and humid conditions in Illinois under
upper level ridging. A long wave trough over the central Rockies on
Friday with lift NE toward Canada this weekend. This will cause a
sharpening of the ridge across Illinois. Southwest flow aloft will
increase as a result, bringing a continued flow of low level warmth
and humidity. Highs will likely maintain in the mid 80s to around 90
Saturday and Sunday, with overnight lows in the mid to upper 60s.
Dewpoints will linger in the mid to upper 60s, creating a muggy
weekend.
Precip chances for the first half of the weekend look to remain
primarily north of Illinois, closer to a warm frontal boundary.
However, there is continued support in the ECMWF, GFS and NAM that a
cold front will push across IL on Sunday or Sunday evening. The NAM
is the fastest, pushing it to the Indiana border by 7 pm
Sunday/00z Mon. The GFS and ECMWF are next in timing, indicating the
front should reach the Indiana border shortly after 06z/1am Monday.
The Canadian Global halts the front near the Mississippi river in
response to cutting off the Plains upper low and drifting it south
toward Oklahoma on Monday. We held with the consensus of a frontal
passage later on Sunday into Sunday evening, with increasing chances
of storms Sunday afternoon west of I-57. Storm chances look to
continue in the post frontal airmass through Monday, as the upper
level trough axis finally progresses across the area.
A cooler and less humid air mass will arrive for Monday, and linger
through Thursday. While we see slight chances of diurnal showers
each day due to steep mid level lapse rates, most areas should
remain dry. High temps from Monday to Thursday should be in the mid
70s, with lows in the mid 50s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1251 PM CDT Thu Sep 22 2016
Mainly thin cirrus clouds were moving east-southeast into central
and eastern Illinois early this afternoon from the remnants of
early morning thunderstorms back in northern Iowa. At the surface
the main synoptic front extended from the central Plains across
central Iowa into southern WI, with an outflow boundary from
southwest WI into eastern IA. These boundaries are expected to
stay north of the region today so a southwest wind should prevail.
A little more mixing than previously anticipated will allow winds
to stay at or a bit above 10kts in central/eastern IL the rest of
the afternoon.
Weak wind fields and very few clouds this evening should lead to
rapid decoupling of the low levels of the atmosphere and pretty
strong inversion. The RAP and CONSShort point to light fog
developing toward daybreak, so included MVFR visibility for the
TAF sites along the I-74 corridor. A lower crossover temperature
at SPI and DEC should keep light fog from forming.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Miller
LONG TERM...Shimon
AVIATION...Miller
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
416 PM CDT THU SEP 22 2016
.SHORT TERM...(This evening through Friday)
Issued at 415 PM CDT Thu Sep 22 2016
Warm front this afternoon has made it down to about I-80 in Iowa. It
will begin lifting back north tonight. This will maintain the cloud
cover overhead through the night and the day on Friday, but precip
fortunately looks to be lacking. There are a couple of reasons for
this. One, we have building heights at h5. Two, the 925-850 winds
will be diverging over the region with a weak segment going from
Iowa toward southern WI and the main push going from the eastern
Dakotas to the western Dakotas. This 925-850 setup looks to stay
with us through the day on Friday with the models showing their
primary focuses for precip through Friday across northeast Iowa into
southern WI and way out in the northern high Plains. As a result,
cut back considerably on PoPs tonight through Friday, with most of
the area remaining dry through the short term. Isolated activity in
the form of mostly showers as opposed to thunderstorms, is looking
to be the best we see as the boundary lifts back north.
.LONG TERM...(Friday night through Thursday)
Issued at 415 PM CDT Thu Sep 22 2016
We will finally get the upper trough to our west out of here by the
end of the weekend, but until then we`ll have a few more periods of
precipitation with which to contend. It appears most activity will
be to our north Friday night with the warm front and better
isentropic lift located there, although some low PoPs for part of
the area are still warranted. The western upper trough will start to
shift east on Saturday, helping the surface low lift north to near
the North Dakota/Canada border and push the cold frontal boundary
east toward Minnesota. We should see fairly SHRA/TSRA develop in a
north-south axis across the area during the afternoon as some upper
divergence and DPVA work into the area and help take advantage of
decent moisture and some instability. Although the cold front will
certainly not be a fast mover, it should move quickly enough to
avoid any widespread flooding issues. But, any additional
precipitation will certainly be problematic at this point, and it
looks like we could have some areas with over an inch of rain from
Saturday afternoon through Sunday morning, and it will unfortunately
be over the central and eastern portion of the area which has seen
substantial rain of late. The cold front will push east of the area
by Sunday evening, but we will then have the upper low and low level
cyclonic flow linger into Tuesday. So, although the widespread
precipitation will be done, we`ll likely see scattered showers
Monday into Tuesday with cool temperatures. Things then dry out and
start warming up for Wednesday and Thursday as the upper low shifts
east and a surface high and rising heights work into the area.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 123 PM CDT Thu Sep 22 2016
Main question this period is how much influence will dry air from east
winds emanating from a Hudson high influence the area. The hrrr
is the most aggressive with pushing MVFR or lower cigs southwest
of the MN river, with most terminals going vfr late this afternoon
and remaining there through much of the night. SREF probs are
similar as well. Was not quite that aggressive with the TAFs, but
did introduce significant VFR periods to WI terminals who will be
closer to the high and was conservative with keeping IFR
conditions tonight confined to RWF. Also kept TAFs dry, with most
models indicating we`ll see two focused areas of precip through
Friday morning. One down toward northeast IA into southwest WI and
the other way back in the western Dakotas.
KMSP...CIGS are the main issue here. We may see a passing shower
Friday afternoon as the warm front lifts back north, but this TAF
period is looking to bring a much needed 30 hour break from
precip. For CIGs, LAMP maintains an MVFR cig the whole period,
which is plausible, but the SREF and HRRR have MSP going VFR
tonight. Of course we could always head the other direction as
east winds are a favorable direction for getting low CIGs, which
is why we split the difference for now and went with a low MVFR
cigs returning tonight.
/OUTLOOK FOR KMSP/
Sat...VFR with MVFR/TSRA likely late. Wind SE at 10g15kts.
Sun...VFR. Wind W-SW 10g20kts.
Mon...Chc mvfr/-shra. Wind SW 5-10kts.
&&
.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&
$$
SHORT TERM...MPG
LONG TERM...
AVIATION...MPG
Area Forecast Discussion
National Weather Service Phoenix AZ
222 PM MST THU SEP 22 2016
.SYNOPSIS...
Showers and a few thunderstorms will be possible today along and
ahead of a cold front moving through the region. This front will
bring gusty winds, drier air, and slightly cooler temperatures for
the remainder of the week. Breezy, but otherwise quiet weather will
be the rule for the weekend and into early next week along with a
warming trend.
&&
.DISCUSSION...
Initial line of showers steadily dissipated as it tracked eastward
across the Phoenix area early this afternoon. In its wake, more
scattered but organized storms have developed across portions of
western Maricopa County within a moist and unstable environment with
dewpoints as high as the lower 70s yielding MLCAPEs exceeding 1000
J/kg. Meanwhile, NAEFS percentiles show a widespread area of
anomalous PWATs, exceeding the 90th percentile across central AZ
extending northward.
Latest runs of the HRRR continue to have a good handle on the
situation and indicate that additional activity will develop this
afternoon before dissipating around 5pm. The strongest storms are
expected generally to the north and west, where temperatures aloft
are cooler and in the vicinity of the strongest deep-layer shear
associated with the closed low across central California. Main
threats include brief heavy rain, strong winds gusts and small hail. Otherwise,
PoPs remain in the forecast overnight for southern Gila County.
Global models continue to suggest strong vorticity-forced ascent
ahead of the trough axis will tap into some residual moisture to
generate scattered showers in these areas.
&&
.PREVIOUS DISCUSSION...
Gusty west winds are expected to develop over the western deserts
this afternoon behind the front, with the strongest winds likely to
occur over favored areas of Imperial county; peak gusts to 35 mph
are likely. There may be some patchy blowing dust occurring due to
the wind, but recent rains in the area will limit the potential for
any significant dust and as such we will not mention blowing dust in
our forecast grids at this time. As far as temperatures go today,
with thickness values lowering to around 576dm and with considerable
lower clouds and showers in the area, high temperatures will fall to
well below seasonal normal values with many lower AZ deserts falling
into the upper 80s to low 90s. Phoenix should see a high around 90
today which would be 8 degrees below normal.
On Friday, the main upper low is forecast to quickly lift off to the
northeast but a much drier and more subsident northwest flow aloft
will overspread the deserts. Outside of a lingering slight chance of
showers over southern Gila County we can expect generally sunny skies
over the lower deserts with continued below seasonal normal high
temperatures. PWAT values are forecast to fall to around one quarter
of inch over much of the lower central deserts by Friday afternoon
and the surface dewpoints in the Phoenix area will fall from the mid
to upper 60s today into the upper teens to mid 20s.
Over the weekend and into next week, dry conditions are forecast
area wide with no threat of precipitation. A large upper ridge will
initially amplify along the west coast giving a dry northerly flow
to the area but early next week the ridge will flatten somewhat but
continue giving dry northwest flow into the lower deserts. Expect
generally sunny days and clear nights this weekend into the middle
portion of next week along with a gradually warming trend. High
temperatures will climb into the mid to upper 90s over most of the
lower deserts by the early to middle part of next week.
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Shower and thunderstorms continue to develop upstream of the Phoenix
area terminals and all terminals stand a chance to see some precip
activity through the evening hours. Airfield vsbys may take a sudden
drop under the heaviest shower activity and resulting winds will
also be on the rather variable and erratic side. Otherwise, CIGs
will linger 3-5kft into the evening before transitioning eastward
with FEW to SCT clouds lingering after sunset. Any continuing shower
activity should move and stay east of the terminals for the
overnight hours.
Southeast California/Southwest Arizona including KIPL and KBLH:
Breezy to windy conditions to persist for KIPL and KBLH as a cold
front continues to pass through the region. Gusts 25 to 30kts will
linger into the overnight, with sustained winds holding in the 10 to
15kt range. Skies will remain mostly clear with any shower activity
remaining well to the east of the River and the terminals.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday...
Very dry northwesterly flow aloft behind a trough to the east on
Saturday will eventually be replaced by a dry ridge of high pressure
on Wednesday along with below normal high temperatures throughout
the period. Breezy to occasionally windy northerly component winds
will prevail out west, especially along the lower Colorado river
valley each afternoon through Monday with gusts of 20 to 28 mph,
although conditions are not expected to reach critical thresholds
at this time. Gusty northeasterly winds will then spread into the
lower deserts and the higher terrain of southern Gila county
beginning Tuesday. Minimum RH of 13 to 20 percent on Saturday will
slowly increase each day until reaching only 20 to 30 percent on
Wednesday. Fair overnight recoveries on Saturday will improve to
fair to good by Tuesday.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter reports may be needed locally this afternoon across the
Phoenix area.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
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DISCUSSION...Hirsch
PREVIOUS DISCUSSION...CB
AVIATION...Nolte
FIRE WEATHER...Sawtelle