Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/01/17
Area Forecast Discussion...Updated
National Weather Service Billings MT
931 PM MDT Fri Mar 31 2017
.UPDATE...
IR imagery showing warming cloud tops across the region and radar
is showing a solid decrease in activity. HRRR continues to
dissipate the activity by 09z so only expect another inch of snow
at most over the Big Horns so have cancelled all highlights. High
clouds moving in from the northwest may slow the development of
fog in areas where precipitation has ended but a lot of moisture
is around so expect some patchy fog to develop. Update sent.
borsum
&&
.SHORT TERM...valid for Sat and Sun...
850 mb frontal zone has been extending from the Bighorn mountains
northeastward through southeastern Montana for most of the day
today. Have seen an inch or more of rainfall in the foothills
today and several inches of snow in the Bighorn Mountains over the
last few hours. Have started to see weakening trends on radar for
the bands over Sheridan and Big Horn counties, but rain chances
will continue into the overnight hours in those locations.
Possible fog development tonight over the central Plains with weak
winds and copious low-level moisture remaining from the rain.
Clearing and warming conditions expected this weekend with
temperatures in the low 60s expected during the day. The next
system arrives Sunday evening, which is a bit earlier than
previous model runs. Models have had significant differences in
the qpf locations through Monday. Bottom line, unsettled and
cooler conditions for Sunday night and Monday, with rain to
rain/snow mix in the lower elevations and a couple inches of snow
in the mountains. Walsh
.LONG TERM...valid for Mon...Tue...Wed...Thu...Fri...
No big changes to the going forecast this afternoon. Pacific trof
drops through the area in an open wave fashion Monday into
Tuesday, with less of an opportunity for a discrete circulation
to develop. This continues a trend that began yesterday toward
lower precipitation totals though chances for a shower remain
fairly high. Best chances for rain/snow look to arrive Monday
night into Tuesday. Amplified ridge builds in for Wednesday and
may persist into Saturday before another Pacific trof builds in.
This provides several dry days in a row with temperatures in the
60s for the area. Chambers
&&
.AVIATION...
Expect MVFR over south central MT and north central WY through
this evening. Rain showers with local IFR should be confined
mainly to south of KBIL and KMLS and near KSHR through this
evening. Fog/low clouds with IFR-LIFR could develop mainly after
05z tonight across the lower elevations affecting KBIL, KMLS,
KSHR and KBHK. The mountains will be obscured this evening.
Obscurations will decrease overnight. RMS/Chambers
&&
.PRELIMINARY POINT TEMP/POPS...
Sat Sun Mon Tue Wed Thu Fri
-----------------------------------------------------------
BIL 039/061 044/059 035/049 031/050 032/058 039/065 042/066
21/U 13/W 54/R 53/W 11/B 11/B 11/B
LVM 033/058 038/056 028/045 025/049 028/057 034/064 038/064
20/U 24/W 44/O 42/W 11/B 11/N 11/B
HDN 039/062 041/061 034/051 030/052 030/059 034/066 038/068
21/U 02/W 54/R 53/W 11/B 11/B 11/B
MLS 040/062 044/062 038/052 033/052 032/059 035/066 041/070
21/B 11/B 35/R 54/W 11/B 00/B 11/U
4BQ 039/061 042/061 036/050 031/048 029/056 033/063 038/068
41/U 01/B 64/R 54/W 21/B 01/B 11/U
BHK 037/060 040/061 035/051 031/049 028/054 030/062 037/067
21/U 01/B 45/R 55/W 21/U 10/B 11/U
SHR 035/058 037/056 032/047 029/047 028/055 032/063 036/065
61/U 13/W 56/O 54/W 11/B 11/B 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Quad Cities IA IL
706 PM CDT Fri Mar 31 2017
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 330 PM CDT Fri Mar 31 2017
With cyclone departing acrs the eastern OH RVR Valley, a large high
pressure complex will look to slide in behind it acrs the upper
Midwest. A passing bout of upper ridge lobe also to adjust itself
acrs the region for the start of the weekend, while the next weather
maker cyclone organizes over the southwestern CONUS.
&&
.SHORT TERM...(This Evening through Saturday)
ISSUED AT 330 PM CDT Fri Mar 31 2017
Tonight...The big challenge will be timing of clearing and resultant
effect on temps and possible ground occurring phenomena such as fog
and/or frost. Clouds have been stubborn to clear locally, and may
have to wait until diurnal processes shut down toward and after
sunset for a more hastened erosion south out of WI and MN. Also
ridge-riding vort max aloft seen on current water vapor loop
spilling down acrs eastern IA currently, not helping any clearing
trends until it passes into east central IL by mid evening. Have
used current satellite extrapolation and timing off latest HRRR ESRL
CIGs prog to try and time clearing from the north. This generally
brings clearing of the lower stratocu deck down to I80 by 8-9 pm,
and almost out of the southern CWA by midnight. Then just a few
streaks of cirrus into the early morning hours.
With light winds with arrival of sfc ridge, the clearing skies, and
moist sfc layer, the concern turns to fog development by early Sat
morning. But most fog progs and HiRes VSBY solutions don`t produce
much fog besides ambient 3-6SM toward dawn which would not be really
zone mention worthy. The processes may go more into shallow layer
ground fog, heavy dew or frost production, if sfc temps can cool
into the mid to lower 30s like forecast. But will expand at least
patchy fog late tonight acrs the north central into eastern third to
half of the CWA, in areas most likely to stay calm under clear skies
the longest. But low confidence in this, and if the entire area
clears out, the entire CWA may be suspect to at least patchy and
valley fog by early Sat morning.
Saturday...We should have at least partial sunshine in the morning
to midday especially acrs the eastern half of the area, before mid
and high level clouds thicken from the west and southwest ahead of
the next incoming impulse. This should allow for enough insolation
to help temps reach fcst highs of the mid to upper 50s in most of
the area, although still wet terrain and weak mixing make for worry
of a temp bust...not to mention if clouds come in even faster.
Half of the various 12z or later model runs keep the area dry thru
00z Sun, while several others break out overrunning light precip
acrs portions of the CWA especially north of I80. Will keep the fcst
dry and bank on dry low to mid layers to keep any precip that manages
to form aloft, in virga form. A few sprinkles at worst.
..12..
.LONG TERM...(Saturday Night through next Friday)
ISSUED AT 330 PM CDT Fri Mar 31 2017
Near to slightly above normal temperatures and several periods of
rain and isolated thunderstorms are the main highlights of the long
term forecast period.
Saturday night, synoptic forcing associated with a large upper low
moving out of the southern plains will be on the increase. A few
showers may spread into the far southwest counties before daybreak.
The initial wave will produce widespread showers through the day on
Sunday. Confidence is lower regarding the path of the second, more
potent wave. Synoptic models continue to indicate a variety of
solutions for Sunday night into Monday, ranging from the mainly dry
GFS, to the ECMWF, which spread significant rain over the entire
area. The best course for now is to keep pops in the 30-50 percent
range. If the ECMWF ends up closer to reality, temps will need to be
lowered quite a bit on Monday.
Looking ahead, the upper ridge will traverse the area Monday night
into Tuesday, ahead of the next significant system. Model spread is
still quite large, as the system will not come on short until late
Sunday. Thus, forecast confidence in track, timing, and impacts
remains very low. Rain is possible as early as late Tuesday
afternoon, and could even extend into Thursday if the less progressive
solutions verify. Have added some isolated thunder for late Tuesday
morning into Wednesday morning, which looks to be the favored period
for WAA. Some severe weather cannot be discounted with such a strong
system, although details are still uncertain. Some snow could even
occur Wednesday night across the north.
Thursday night into Friday, the amplified upper trough will begin to
head east as cool air settles over the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
ISSUED AT 702 PM CDT Fri Mar 31 2017
Low clouds with MVFR bases will dissipate from north to south this
evening. Then, VFR conditions will prevail with fair skies and light
northerly winds and possibly light fog toward morning. Saturday will
be fair with increasing high clouds in the afternoon as winds shift
to light easterly.
&&
.HYDROLOGY...
Issued at 1139 AM CDT Fri Mar 31 2017
Latest trends support cancelling the flood watches on the Wapsipinicon
River near DeWitt and the Iowa River at Marengo. DeWitt has crested
below flood stage and is on the way down, while Marengo is now forecast
to crest around a foot below flood stage.
Elsewhere, rises continue on the Rock River. Latest forecasts call
for crests near flood stage.
Looking ahead, additional rainfall Sunday into Monday does not look
to be enough to cause significant additional rises. However, another
more potent storm around mid week shows some potential for moderate
to locally heavy rainfall.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...RP Kinney
AVIATION...Nichols
HYDROLOGY...RP Kinney
Area Forecast Discussion
National Weather Service Lincoln IL
914 PM CDT Fri Mar 31 2017
.UPDATE...
Issued at 910 PM CDT Fri Mar 31 2017
Made a few adjustments to the cloud cover rest of tonight, but
otherwise forecast seems on track. Low clouds were decreasing
along and north of I-80 at mid evening and will decrease from
north to south overnight over central IL, lasting longest in
southeast IL into Sat morning. Lows by dawn to range from lower
30s from Lincoln north, to the upper 30s to near 40F in southeast
IL which stay cloudy tonight. North winds 5-15 mph this evening to
be 5-10 mph overnight.
02Z/9 pm surface map shows 1004 mb low pressure over sw PA while a
deepening 1002 mb low pressure was just off the mid Atlantic
coast. Aloft a 553 dm 500 mb low/trof was over western NY/PA and
extending into central VA. Models deepen surface low pressure off
the southern New England coast by dawn Sat while upper level trof
pushes off the Atlantic coast. Meanwhile upper level ridge over
the central plains shifts eastward toward IL/MS river valley by
Sat morning. 1025 mb surface high pressure along the southern
Saskachewan and Manitoba province line to build over IA by dawn.
This will continue to decrease the MVFR clouds from north to south
over central IL overnight and over southeast IL Sat morning.
Overcast low clouds holding temps in the low to mid 40s at mid
evening. But once low clouds decrease, temps should slip into the
30s, while southeast IL from I-70 southeast only drops to around
40F where low clouds continue rest of tonight into part of Sat
morning.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 242 PM CDT Fri Mar 31 2017
Clouds continue to blanket central Illinois this afternoon, with the
closest clearing observed well to the north across central/northern
Wisconsin. As low pressure currently over eastern Ohio moves
further away, this area of clearing will pivot southward tonight.
HRRR continues to suggest skies will begin to clear north of Peoria
by late evening...with clearing advancing southward into the
Springfield area toward dawn. Given a continued N/NE fetch within
the cloud-bearing layer, think the eastern KILX CWA along and east
of I-57 will remain cloudy through the entire night. Overnight low
temperatures will be coldest in the lower to middle 30s where
clearing occurs soonest...but will remain around 40 degrees further
southeast where clouds will persist. Low clouds will eventually
exit the E/SE KILX CWA on Saturday: however, increasing high clouds
ahead of the next system will generally yield a partly sunny day.
Despite the partial sunshine, a cool northeasterly breeze will keep
high temperatures in the middle to upper 50s.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 242 PM CDT Fri Mar 31 2017
The upper air pattern over North America is expected to remain
very active through this forecast period as a powerful 250 mb jet
tracks across the central Pacific. Several low amplitude waves
embedded in the fast flow over the Pacific track into the western
U.S. and amplify as the move into the longwave trough position
over the western U.S. Based on morning upper air analysis, there
appears to be at least 3 distinct waves that we will have to deal
with over the next 5 to 7 days, bringing rain chances to central
Illinois just about every 2 to 3 days. Unfortunately, with such an
active/fast flow across the Pacific, timing and magnitude of
these low amplitude waves into the country and east through the
southern Plains and Midwest are a challenge for models and
continue to be so with the 12z runs. This will continue to keep
chance POPs going a majority of the days in this forecast period.
The first of these waves shows up quite nicely on satellite data
over northern Arizona and with track east across the southern Plains
with most models continuing to shift the upper wave mainly to the
east early next week. The main question with this sytem will be the
amount of low level moisture able to advect north with as much
convection that is forecast along the lower Mississippi Valley
later in the weekend into early Monday. The latest ECMWF, and to
a certain exent the NAM, show quite a bit of convection well
south of our area with both models suggesting some convective
feedback issues resulting in a further north track with the
surface low. Based on the stronger 500 mb wind fields displaced
further south, the track suggested by the GFS looks more reasonable
at this time. Rain with this system will approach our area later
Sunday as low level warm advection increases in advance of the
upper. Shower and low thunder chances continue Sunday night into
Monday as the surface wave tracks south of the region with the
highest rain chances along and south of I-72. With the next
upstream kicker/shortwave trough already pushing into the central
Rockies later Monday, the early week wave should progress east of
the area Monday night into early Tuesday taking most of the
precip to our east.
Models continue to suggest a more vigorous system amplifying across
the Rockies and into the Plains late Tuesday into Wednesday bringing
another round of showers and thunderstorms to parts of the region.
Main question with this system will be with the amount of low level
moisture available ahead of the strong wave as the previous shortwave
that brought the rains to our area on Monday will scour out the low
level moisture as it shifts off to our east Monday night into Tuesday.
However, models have trended slower with the mid-week system which
may allow Gulf moisture to return, at least over our east and southeast
counties Wednesday afternoon. Believe the slowing trend seen with
the 12z models may be the way to go with this more amplified upper
trough, as we see little in the way of a significant upstream
kicker/shortwave to its west as the system closes off a low at
500 MB just to our west late Wednesday. Showers, and at this point,
low thunder chances will push into the west late Tuesday, more
likely Tuesday night and Wednesday with any pre-frontal convective
activity slated for Wednesday afternoon/evening based on the slower
trends in models. As the system, shifts across our area Wednesday
night into Thursday, a weak wave trailing along the southern
periphery of the deepeing upper trof may bring a continuation of
the showers along with a change to colder weather for the end of
the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 659 PM CDT Fri Mar 31 2017
1004 mb surface low pressure over sw PA and 553 dm 500 mb low
over the upper/eastern Ohio river valley, will track off the mid
Atantic coast by 06Z/1 am tonight. Upper level ridge over the
central plains will shift east into IL by 18Z/Sat while 1024 mb
high pressure over southeast Saskachawan settles into IL.
Widespread MVFR ceilings of 1-2.5k ft over central IL early this
evening (as low as 900 ft at BMI) while these clouds scatter out
north of IL over southern WI and northeast IA. Went a couple hours
slower than the HRRR model with scattering out these clouds at
PIA around 05Z, along I-55 between 07-09Z and at DEC and CMI
10-12Z. Will see scattered to broken cirrus clouds around 25k ft
spread into central IL Sat morning. NNW winds 7-13 kts early this
evening to weaken during tonight and veer NE during Sat morning.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...07
SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...07
Area Forecast Discussion
National Weather Service Indianapolis IN
1151 PM EDT Fri Mar 31 2017
.UPDATE...
The Aviation section has been updated below.
&&
.SYNOPSIS...
Issued at 318 PM EDT Fri Mar 31 2017
Cool...cloudy weather will persist through early Saturday as low
pressure moves away from the region. A dry and seasonable weekend
is then expected with high pressure moving through the Great
Lakes. The active and unsettled weather pattern of late will
return for next week with two separate systems impacting the Ohio
Valley during the early and middle part of the week.
&&
.NEAR TERM /Tonight/...
Issued at 1045 PM EDT Fri Mar 31 2017
Going forecast is in excellent shape, although did tweak min temps
down slightly per latest HRRR and obs trends, which particularly
pointed out the northwestern portion of the area with potential to
get a couple of degrees cooler than forecast. Previous discussion
follows.
Issued at 318 PM EDT Fri Mar 31 2017
Chilly..raw and damp day ongoing across central Indiana as the
region resides in the backwash of the surface low tracking east into
western Pennsylvania late this afternoon. Trailing surface trough
extending W/SW from the low remains across the southeast portion of
central Indiana with the bulk of the steadier light rainfall and
drizzle focused near and east of the trough. Temperatures had slowly
fallen over much of the area as the afternoon progressed. 19Z temps
ranged from near 40 in the lower Wabash Valley to the mid 50s just
ahead of the boundary over the far southeast sections of the
forecast area.
Upper low and aforementioned surface wave will continue to move away
to the east with energy transferring to a deepening surface low off
of the Mid Atlantic coast tonight. More persistent and widespread
light showers will move into Ohio by late this afternoon with the
surface trough. While some lingering spotty light showers and/or
drizzle will remain a possibility through early evening...expecting
dry weather tonight as surface ridging begins to encroach on the
Ohio Valley from the west.
While the drier air will progressively expand into the region
tonight...the focus will be in the mid levels with deep moisture
remaining trapped within a shallow layer in the low levels. Model
soundings and RH progs indicate a sharpening to the inversion
tonight due to the advection of the drier air above 5kft. This will
maintain the thick stratus deck residing across the Ohio Valley and
Great Lakes all night for much of the region. Cyclonic flow
persisting over the region will support a continued northerly flow
tonight with winds at 5-10mph. Cannot entirely rule out pockets of
drizzle at times overnight as well...but confidence is not high
enough for a mention in the forecast at this time.
Temps...MOS guidance looks far too cool tonight considering presence
of the stratus and likelihood that the lower levels cannot decouple.
Raw model guidance matched low level thermals much more closely with
lows ranging from the mid 30s north to around 40 south of Interstate
70.
&&
.SHORT TERM /Saturday through Monday/...
Issued at 318 PM EDT Fri Mar 31 2017
Forecast challenges focus on how quickly the stratus mixes out on
Saturday...temps through the weekend...and rain/thunder potential
Monday with the next storm system set to impact the Ohio Valley.
Progressively drier air and subsidence will overspread the forecast
area from the northwest on Saturday and should finally work its way
into the boundary layer by late morning which will finally weaken
the inversion and enable scattering of the low clouds around midday.
The center of the surface high will drift across the region Saturday
night into Sunday keeping weather quiet and bringing partly cloudy
skies at a minimum. The sun will make its reappearance for Saturday
afternoon with a period of mainly clear skies lingering into
Saturday night before more expansive mid and high level clouds lift
up and overtop of the expanding ridge aloft and across the region.
Focus for the latter half of the short term is on the deep upper low
currently residing across the Four Corners region this afternoon.
The upper energy will kick out east into Texas and the southern
Plains by late weekend before being drawn northeast into the Ohio
and Tennessee V6alleys by late Monday.
Initially Sunday...east-southeast winds will maintain dry air
through the lowest 10kft or so even as mid and high level clouds
continue to increase as moisture aloft surges into the region.
Saturation within the boundary layer will likely not come until the
predawn hours Monday as deeper isentropic lift commences through the
column with the expansion of moisture into the Tennessee Valley
along a developing warm front. Will hold off on any precip mention
until late Sunday night as a result...with the combination of
moisture overrunning the frontal boundary and increasing lift
supporting a rapid expansion in rainfall coverage over the region by
early Monday.
Still some model differences in play at this point...but overall
consensus is for the frontal boundary to set up near the Ohio River
on Monday with a surface wave set to track along it. Precip water
values will rise above 1.25 inches over most of the forecast area
Monday and the combination of deep moisture and lift warrant
categorical pops. Enough instability aloft noted across the area to
continue with a mention of thunderstorms for Monday as well. Looks
like potential certainly there for another spring soaking with up to
an inch possible for most of central Indiana by early Tuesday once
the system departs.
Temps...considering the uncertainty with how quickly the low clouds
mix out Saturday...trended highs towards the cooler MAV guidance in
the mid 50s most areas. Should see temps surge into the 60s for both
Sunday and Monday and low level thermals support. Utilized a model
blend for lows through the period.
&&
.LONG TERM /Monday night through Friday/...
Issued at 252 PM EDT Fri Mar 31 2017
Monday night a system will be moving through to the south of the
area keeping rain and chances for storms in the area early with
precip ending from northwest to southeast by morning as dry
conditions advect in. Tuesday brief upper ridging will slide
through to keep dry conditions in place until Tuesday night, when
a weak wave will bring in some shower chances overnight. An upper
low will wrap up before swinging out of the plains and through the
Midwest, and this will bring chances for rain and thunderstorms
Wednesday and Wednesday night, with more showers possible
Thursday. Thursday night in the wake of the cold frontal passage
temperatures will plummet, and it looks like these cooler
temperatures will hang around for a couple days at least. With
some upper forcing rotating through the upper low north of the
area could see some chances for a rain/snow mix to end the week.
&&
.AVIATION /Discussion for the 01/06Z TAFs/...
Issued at 1151 PM EDT Fri Mar 31 2017
Widespread MVFR ceilings will persist through the night. VFR
conditions appear likely to return tomorrow afternoon.
Widespread cloud cover noted on satellite imagery trapped beneath
a stout subsidence inversion aloft. This inversion will persist
through the night and into Saturday, which will keep the cloud
cover in place.
Clearing has progressed across northern Illinois but has struggled
to make eastward progression. Will have to monitor this overnight.
Ceilings will gradually lift Saturday morning and VFR conditions
will likely return by early afternoon.
Winds throughout the period will generally be northwesterly
through northerly at 10KT or less.
No significant obstructions to visibility are expected through the
period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...Ryan
NEAR TERM...Ryan/NIELD
SHORT TERM...Ryan
LONG TERM...CP
AVIATION...NIELD
Area Forecast Discussion
National Weather Service Omaha/Valley NE
625 PM CDT Fri Mar 31 2017
.SHORT TERM...(Tonight through Monday)
Issued at 305 PM CDT Fri Mar 31 2017
Main forecast concerns are timing and amounts of precipitation,
especially from Saturday into Sunday.
System that brought rain to the area earlier in the week continued
to move off to the east, and a new closed low was over the four
corners region. That system had 12 hour height falls of over 200
meters this morning in Arizona. There were also 120 knot jetstream
level winds on the west and south sides of that system. 850 mb
moisture across the southern and central parts of the Plains was
pretty low.
Tonight, we should see some breaks in the cloudiness which will
allow temperatures to fall into the 35 to 40 degree range for
lows. Surface ridge axis will slide east, and just how much that
will affect the development of showers is not known. The RAP and
experimental HRRR runs seem to suggest showers are possible by
around sunrise Saturday across southeast Nebraska. The 12Z NAM
also developed precipitation, but much heavier.
The main closed should drop to the southeast through Saturday,
then move east or southeast through Sunday and start to open up.
By Sunday evening, a shortwave trough should be digging southeast
toward Idaho. That will move southeast and strengthen slightly.
In general, model agreement is OK from Saturday Night into
Monday. Chances for amounts of 0.25 or higher will be across
southeast Nebraska and southwest Iowa, closest to the forcing
from the system to the south.
.LONG TERM...(Monday night through Friday)
Issued at 305 PM CDT Fri Mar 31 2017
The 12Z GFS and Canadian models develop a closed 500 mb
circulation near the NM/CO/OK border area by mid day Tuesday,
then track that northeast through Wednesday. Current indications
suggest there will be enough elevated instability for some
thunderstorms into the southern parts of the forecast area for
Tuesday afternoon into Tuesday night. But the operational GFS
solution looked too strong with the 500 mb low. A ridge over the
Rockies on Wednesday/Thursday, should build over the region with
dry conditions Thursday night into Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 621 PM CDT Fri Mar 31 2017
VFR cigs near FL040 and light northeast winds can be expected
through at least 06Z, then cigs will lower to MVFR at KLNK and
KOMA before 12Z. Areas of MVFR fog are also possible at all sites
around 12Z. Rain is forecast to move in from the southwest,
initially spotty much of the day Saturday so was not mentioned in
TAFs. More widespread rains affecting KOMA and KLNK are expected
after the end of the TAF period.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Dergan
Area Forecast Discussion
National Weather Service Blacksburg VA
1136 PM EDT Fri Mar 31 2017
.SYNOPSIS...
A cold front will move east across the region and move into thew
Atlantic ocean tonight. High pressure will build across the region
for the weekend.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1130 PM EDT Friday...
Upper level low and vorticities waves beginning to move east of
the Blue Ridge late this evening. Deep northwesterly flow has
cleared rain out over the piedmont. Same northwest flow across
the mountains has thick low clouds with rain along western
slopes and drizzle elsewhere. Precipitation, especially along
western slopes, will continue through sunrise with low clouds
lingering into the afternoon.
Not much cold air behind the front. Morning lows will range in
the 40s across the mountains to near 50F east.
As of 535 PM EDT Friday...
Updating PoPs as convection tracks east of the area earlier than
expected. Upper level low continues to spin over the Ohio
Valley this evening to keep bands of light showers rotating
across the mountains. Highest PoPs through the night will be
along western slopes of SE WV. Pressure rises behind the front
will also bring breezy and gusty conditions to the mountains
tonight.
As of 320 PM EDT Friday...
Residual cool wedge across northeast portion of forecast area this
afternoon will erode as warm front pushes north this afternoon into
tonight. Meanwhile, cold front continues to march east into the
mountains. This cold front will move east tonight and push further
out into the Atlantic ocean overnight. High pressure in the Ohio
Valley will build southeast into our region on Saturday.
Severe threat will be rather short lived, with the convective line
reaching the Atlantic coast by/just after sunset, nocturnal
stabilization and the advancing front should allow for threat to
drop off quickly. The best chances of strong storms are where
temperatures have warmed into the lower 70 degrees F with dewpoints
in the lower 60s. Across southern portions of Forecast area, 0-3 km
lapse rates are steepening and may aid in leading to potential for
localized damaging winds as storms develop and intensify. Strong
southwesterly low- to mid-level flow (40-55 kt at 500 mb) will serve
to organize updrafts. The main threats will be hail and gusty winds
with the stronger cores as storms develop eastward near/along the
NC/VA border this afternoon into tonight. The Storm Prediction
Center in SWODY1 has outlooked areas east of a LYH-DAN line for
Slight Risk of severe weather for this afternoon into tonight.
Shaped the pops in isc grids towards a blend of HRRR and HiResw-arw
East.
In the wake of cold front, conditions will improve with clearing
taking place tonight. As High pressure builds in for tonight, expect
breezy conditions with northwest winds of 15 to 25 mph. West of the
Blue Ridge, and more so for the higher terrain of WV and far western
VA and into the NC mountains, some lingering low clouds and light
precipitation (showers) may continue per shallow moist northwest
flow. Low temperatures tonight will range from the upper 30s in the
northern mountains to near 50 in the Piedmont.
Northwest flow aloft returns for Saturday. Under cold advection
aloft, 850 mb temperatures by early afternoon cool to values ranging
from +1 to +5C. Any lingering upslope showers along the western
slopes will dry up quickly. Utilized the NAM and continuity for pops
on Saturday. High temperatures will vary from the the mid 40s in
northwest Greenbrier county to the lower 70s in the Piedmont.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 319 PM EDT Friday...
High pressure is firmly in control at the start of the period. Winds
will have begun to die down as the pressure gradient weakens. Skies
will be sunny providing a benign Sunday with high temperatures in
the 60s.
Overnight on Sunday into Monday, the high will begin
shifting eastward as a low begins to track toward the region from
the midwest. Increased cloud cover will begin to move in ahead of
the low and also from a shift to a southerly flow. Showers begin to
move into the region Monday morning, beginning mainly in the
mountains of northwest NC. Over the course of the day precip looks
to be limited along the ridge early until larger scale forcing moves
in to cause the PoPs to be more likely everywhere. The heaviest
amounts be along and near the Blue Ridge. Isolated thunder within
the showers can be expected. All in all, the situations looks to
play out very similarly to what we have seen the past 18-24 hours.
Heaviest and mostly likely PoP looks to occur during the afternoon
into the evening.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 319 PM EDT Friday...
Winds will begin to pick up Monday night into Tuesday as the
pressure gradient begins to strengthen around the low. These
increased winds should first be noticed along the southern ridges as
850mb winds during the morning are between 40-50 kts from the south
at this point. Post frontal passage, winds will shift westerly and
stronger gusts will be seen throughout the region.
Wrap around moisture from the low will continue to be an issue for
the region Tuesday into Wednesday. This will be particularly
noticeable in the northwest ridges which are typically susceptible
to upslope precipitation as well. Models still have a lot of
variance regarding the timing and strength of the next system to
reach the region on Thursday. As of now, leaning toward the European
solution which shows the onset of at least some light precip early
in the morning Thursday.
After this system passes, temperatures will be noticeably cooler for
the end of the week into the weekend, so much that some nocturnal
snow may be seen along the western ridges late Friday night.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
As of 722 PM EDT Friday...
An upper level low pressure over the Ohio Valley will continue
to track east to the Mid Atlantic region overnight. The trailing
cold front will move east of the piedmont (KLYH-KDAN) by 01Z
Saturday/9pm Friday.
Skies will remain cloudy across the forecast area through
midnight then downsloping winds will help scour clouds east of
the Blue Ridge. Upslope winds and low level moisture will keep
skies cloudy across the mountains into Saturday morning. A few
light rain showers may pass over the mountains overnight, but
any reducing visibilities will be those along western slopes
(KBLF). Ceilings along western slopes will also remain MVFR to
tempo IFR into Saturday morning. Across the rest of the
mountains, ceilings will range from 2500-3500 feet.
Pressure rises and gradient will keep breezy and gusty
conditions along and west of the Blue Ridge into Saturday
afternoon. Breezy conditions are expected across the piedmont
once inversion breaks by 9 AM Saturday.
Medium confidence in ceilings, visibilities and winds during the
taf period.
Extended Aviation Discussion...
VFR will return for Saturday evening through Sunday under
diminishing winds as high pressure slides across. Next similar
low pressure system to that seen at the end of this week will
approach by Monday with sub-VFR conditions likely returning
Sunday night into Monday as rain again transitions to showers
and storms to start the week.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...KK
NEAR TERM...KK/RCS
SHORT TERM...JR
LONG TERM...JR
AVIATION...KK/RCS