Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/12/18
Area Forecast Discussion
National Weather Service La Crosse WI
556 PM CDT Sun Mar 11 2018
.SHORT TERM...(This evening through Monday)
Issued at 218 PM CDT Sun Mar 11 2018
Early afternoon surface analysis showed a weak surface cold
front/wind shift extending from east-central Minnesota through
central Iowa. Visible satellite showed an expansive area of stratus
stretching from the Minnesota/Canadian border south through the
local forecast area, reaching as far as southern Missouri and
Kansas. The stratus will remain over the area through Monday.
Morning RAP runs indicated clearing for areas west of the
Mississippi River on Monday morning, though the latest runs trended
farther west with the western edge of the clouds, similar to the
11.12Z NAM, GFS, and ECMWF, so only a small portion of the area may
see clearing before clouds fill back in Monday afternoon.
Despite the widespread low clouds, any precipitation chances are
confined to the far northern forecast area as an upper level short
wave slides just north of the area this evening, potentially
providing just enough lift to squeeze out some flurries and/or
sprinkles. Another slightly stronger wave will take a similar path
Monday afternoon/evening, but little to no snow accumulation is
expected.
Temperature-wise, expect lows tonight in the 20s and highs tomorrow
in the 30s to lower 40s, but cloud trends will certainly play a role
in this. Should southeast Minnesota and northeast Iowa see a bit
more clearing tonight, may need to bump down lows tonight and bump
up highs Monday.
.LONG TERM...(Monday night through Sunday)
Issued at 218 PM CDT Sun Mar 11 2018
11.12Z models are in agreement that there will be long wave
troughing in place over the eastern part of the country to start
the week. A system coming across eastern Canada will help to
amplify this troughing and an embedded short wave trough will
cross the Great Lakes and bring some weak forcing across
Wisconsin Monday night. This forcing could be enough for a little
bit of light snow south of Lake Superior with some flurries
possible over all but the far western sections of the state.
Outside of this system, there does not look to be a chance for any
precipitation until late in the week.
As the eastern trough moves slowly out over the Atlantic, the long
wave ridging over the Rockies will slide east and over the Midwest
for the middle of the week. This will allow some warmer air to
move over the region with highs Thursday and Friday expected to be
in the 40s to lower 50s.
The chances for some precipitation will also return starting
Friday and continue on and off through the weekend. Right now, the
models are in agreement of a cut off low with long wave troughing
developing off the Pacific Coast during the middle of the week. A
short wave trough ejected from this system looks to top the ridge
axis and move across the Upper Midwest Friday and Friday night.
This will bring a chance of rain to the area with a little bit of
light snow possible Friday night. The Pacific system then looks to
open up and move east over the weekend with the remains of it
coming across the region Sunday. Some differences between the
models on how strong the system will still be at that time, but
with temperatures remaining in the 40s and 50s, will again be
mainly rain with a little bit of light snow possible Saturday
night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 556 PM CDT Sun Mar 11 2018
Big variety of flight categories across the area this evening,
ranging from some LIFR near the Minnesota-Iowa border to generally
VFR conditions in southern Wisconsin.
Weak short wave passing through just enough to provide subtle lift
and with weak cold air advection, producing brief period of lower
visibilities just along cold front. Expect this lowering trend to
move in this evening, but then improve somewhat as wave passes.
Still likely looking at IFR conditions though for most until higher
ceilings make it closer to daybreak Monday.
Some clearing expected from the west, but next short wave that drops
into western Great Lakes Monday could swing clouds back in from the
north.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...CA
LONG TERM...04
AVIATION...Shea
Area Forecast Discussion
National Weather Service Bismarck ND
938 PM CDT Sun Mar 11 2018
.UPDATE...
Issued at 938 PM CDT Sun Mar 11 2018
Going forecast remains in good shape. No changes needed.
UPDATE Issued at 635 PM CDT Sun Mar 11 2018
Going forecast remains in good shape with areas of fog expected
later on. Some models continue to be more aggressive with the fog
and some continue to hold back. Therefore, feel a mention of
areas of fog throughout western and central North Dakota continues
to be a good choice.
&&
.SHORT TERM...(This evening through Monday)
Issued at 137 PM CDT Sun Mar 11 2018
Fog potential and temperatures will be the main forecast problem
in the short term period.
Currently, high pressure is situated over the MONDAK region with
westerly winds of 5 to 10 mph over the forecast area and sunny
skies. Temperatures got a slow start this morning but have
recovered nicely and are in the 20s to mid 30s.
Expect full sunshine for the remainder of the afternoon with the
potential for a rise of a few more degrees most areas.
The main forecast challenge tonight will be the potential for fog
development most anywhere within the CWA. Forecast models bring
the surface high into central North Dakota by 12 UTC Monday. A
light northerly flow remains over eastern portions of central ND
with the sfc ridge axis over central ND and little or no return
flow until you get into far western ND. We utilized a blend of
some of the colder guidance for low temperatures tonight with
readings in the single digits above zero to the lower teens. With
widespread cold temperatures and clear skies, most areas are
expected to drop below their crossover temperature, so the
potential for radiation fog looks pretty good. Mesoscale models
are all showing hints of fog (in varying degrees) over western and
central ND. NAM RAP and GFS Bufkit soundings all show the
potential for fog late this evening into Monday morning.
We do think there will be some fog tonight into Monday. Problem
is, with the expansive surface high, it could occur most anywhere
within the CWA. It does appear that the moisture is shallow,
comprising only the lowest couple hundred feet of the atmosphere.
And there is the question about exactly when and where it does
develop. We decided to mention areas of fog rather than patchy,
across most of the CWA. Will let the evening and overnight shifts
fine tune and handle any highlights as uncertainty remains in how
dense and widespread the fog may become.
Once fog dissipates on Monday it should be mostly sunny with highs
mainly in the 30s.
.LONG TERM...(Monday night through Sunday)
Issued at 137 PM CDT Sun Mar 11 2018
The surface high pressure ridge mentioned in the short term does
not move very far east Monday and we will probably see another
period of fog Monday night into Tuesday morning.
Exactly when and where any fog develops and how long it remains
each morning could end up playing havoc with our forecast
temperatures early to mid week. But in general we are anticipating
quiet weather (not including fog) through mid week as high
pressure remains in control at the surface and aloft. Highs are
expected to be in the upper 20s to upper 30s Monday, mostly 30s on
Tuesday, and mid 30s to upper 40s Wednesday.
As we move into the latter portions of the work week (Thu-Fri) and
through the weekend, a western U.S. trough will begin to influence
our weather. The GFS is the most progressive of the medium range
models bringing the initial shortwave energy from the western
trough, across the forecast area Thursday into Friday. The ECMWF
and Global Gem are more stubborn with the downstream ridging ahead
of the upper low, lingering over the northern plains into the
early weekend. Either way, at this time it appears like small
chances of precipitation, either Thursday into Friday (GFS),
Friday into Saturday (GEM) or maybe nothing at all (ECMWF). A more
potent wave moves into the central portion of the U.S. late in the
weekend. Still a lot of uncertainty at this time but the medium
range model consensus is to keep the brunt of this system to our
south, with only the GFS bringing QPF into our far southern
counties. It is a potent system, so will need to monitor through
the upcoming week.
Temperatures cool late week and through the weekend but still
remain seasonable with mostly 30s for highs and teens for lows.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 635 PM CDT Sun Mar 11 2018
Areas of fog are expected to develop over central and western
North Dakota late this evening and remain through mid-morning
Monday. With that said, there is still a lot of question on
exactly where the fog will develop and how poor visibility can
become. Therefore, will mention visibility reduction for ISN as
higher confidence exists there, and will mention VCFG in remaining
locations until we have higher confidence on the fog development.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJS
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...JJS
Area Forecast Discussion
National Weather Service Caribou ME
1043 PM EDT Sun Mar 11 2018
.SYNOPSIS...
Low pressure will begin to move east into the Canadian
Maritimes overnight as weak high pressure builds north of the
area into Monday. Low pressure will develop off the southeast
coast Monday and then intensify as it moves northeast toward
Nova Scotia by early Wednesday.
&&
.NEAR TERM /THROUGH MONDAY/...
1045 PM Update...
Snow that set up earlier across the County has died out w/one
last batch dropping through the Masardis and Oxbow region as
convergence weakens. The 00z CAR sounding showed moisture
hanging in below 850 mbs and cooling overnight will allow for
some fog development. The 00Z NAM and RAP support this setup and
decided to add fog overnight into Monday morning. Clouds were
hanging on mainly over eastern areas including the Downeast
while the rest of the region showed clearing. Low clouds look
like they will set up by early morning especially across the
northern and eastern border w/the fog. This will also hold
temps up some. Clayton Lake down to 21F w/clear skies and light
winds. Temps will drop into the teens especially across the w
and nw areas where clearing will hold on.
Previous Discussion...
Expect mainly cloudy skies across northern and central areas
overnight and partly cloudy down east. Lows tonight will range
from the low to mid 20s north and mid to upper 20s north.
Weak ridging will remain across the region on Monday with mainly
cloudy skies north and central areas and partly to mostly cloudy
skies down east. Highs on Monday will be in the mid to upper 30s
north and lower 40s central and down east.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Cldnss will increase from SW to NE Mon ngt as intensifying
secondary sfc low pres from the SE states begins to apch from
the SW. Sn from this system first onsets into SW Downeast areas
erly to mid morn Tue and spreads Nwrd to the St John Vly by late
aftn.
Best mdt/hvy snfl banding again looks to set up for Downeast and
Wrn ptns of the FA Tue aftn into Tue eve before weakening and
lifting toward E Cntrl areas ovrngt Tue. Subsequently, similar
to the last major system from this past midweek, greatest snfl
potential will be ovr Downeast and Cntrl highland areas as sfc
low pres tracks toward Wrn Nova Scotia, but with lesser cut-off
of stm total snfl to Nrn and Ern areas, so that we can confidently
issue an area wide wntr atm watch. Organized banding of snfl
will first lift N of the Srn hlf of the FA by Wed morn and last
out of far Nrn areas by Wed eve.
Cldnss and sn shwrs will then be most persistent across the N
hlf of the FA Wed ngt as upper lvl low pres lingers ovr New Eng.
Temps will cont fairly mild, cold enough for a sn event across
our FA, xcpt perhaps briefly mixed with rn attms alg the
immediate Downeast coast late Tue aftn into the ovrngt hrs,
with the trend of ovrngt lows contg to be well abv avg for this
tm of season. Sn will mix with rn across much of Downeast ME by
Wed aftn and erly eve as precip lightens and transitions to
shwrs as Sfc-BL temps rise abv fzg.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Sfc low pres will only slowly exit NE of the Gulf of St
Lawrence Thu as upper low pres finally opens up and exits E of
ME. This will keep cldnss and sct sn shwrs and aftn lower trrn
rn/sn shwrs going spcly ovr Nrn ptns of the Rgn. Conditions then
gradually improve Fri into the weekend with progressively less
in the way of sn shwrs and cld cvr with slightly colder temps as
the first fresh semi-arctic air mass arrives from Cntrl Can in
about 2 to 3 weeks.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
NEAR TERM: Any remaining diurnally driven snow showers will be
winding down by late afternoon. VFR ceilings early this evening
are expected to lower to MVFR later tonight, mainly
KFVE/KCAR/KPQI/KHUL, otherwise VFR elsewhere. MVFR ceilings
across the north are likely to persist into Monday morning
before giving way to VFR by afternoon.
SHORT TO LONG TERM: VFR conditions xpctd Mon ngt...then clgs and
vsbys lowering to IFR and then LIFR/VLIFR in sn from SW to NE
across the TAF sites Tue, contg Tue ngt into Wed before
improving to MVFR from SW to NE Wed aftn into Wed ngt.
Conditions improve to VFR Downeast sites Thu, but cont MVFR
across Nrn TAF sites in clds and ocnl vsbys with sn shwrs. All
sites should then be VFR later Thu ngt thru Fri.
&&
.MARINE...
NEAR TERM: Wind/seas will remain below advisory levels through
the day Monday.
SHORT TO LONG TERM: Winds and seas ramp up quickly late Mon ngt
thru Tue morn to potential gales ovr the inner bay and harbor
waters to potential storm force ovr our outer waters by Tue aftn
into Tue eve. Winds and seas will then slowly decrease ovrngt
Tue and Wed with an intervening gale hdln likely needed ovr our
outer MZs and an SCA for our inner bay/harbor waters. Kept close
to blended WW3/NWPS guidance for fcst wv hts.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Watch from Tuesday afternoon through Wednesday
evening for MEZ001>006.
Winter Storm Watch from Tuesday morning through Wednesday
afternoon for MEZ010-011-015>017-029>032.
MARINE...Gale Watch from late Monday night through late Tuesday night
for ANZ052.
Storm Watch from Tuesday afternoon through Tuesday evening for
ANZ050-051.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Des Moines IA
615 PM CDT Sun Mar 11 2018
.SHORT TERM.../Tonight through Monday/
Issued at 317 PM CDT Sun Mar 11 2018
Day Cloud Phase Distinction RGB from GOES-East shows plenty of
clouds over the western part of the state with breaks in the clouds
over south central Iowa with even more sunshine over southeast Iowa
at 230pm. However, to the north and west GOES imagery shows plenty
of clouds with a back edge from International Falls, MN to near
Aberdeen, SD to near O`Neill, NE. Therefore, any peeks of sunshine
or clear sky this afternoon or early this evening will give way to
clouds as low stratus moves over the state. Beneath the stratus,
question is whether there is enough moisture depth and lift for
freezing drizzle or squeeze anything out. Cross sections and
soundings from the NAM and RAP and less so with the GFS show low
level saturation around 1km with dry air above this moisture.
However, lift is quite weak with a microbar/second or so at best.
Therefore, will keep the forecast dry overnight at this time.
The clearing edge of the clouds will reach the northwest part of the
forecast area after midnight and move southeastward through the
remainder of the night into Monday morning. Much of central Iowa
will have ample sunshine by late morning at the latest. While an
upper level trough will begin to develop over the eastern US on
Monday, this will keep Iowa within a northwest flow regime as a
surface high pressure approaches from the Dakotas. Winds may perk up
a bit late in the morning into the afternoon being sustained at 10
to 20 mph. Sunshine will help to warm temperatures tomorrow as 850mb
temperatures maybe rise 1 or 2C. Highs will range from the the low
30s near the Minnesota border to the 40s over central and southern
Iowa.
.LONG TERM.../Monday night through Sunday/
Issued at 317 PM CDT Sun Mar 11 2018
Upper ridging will commence to the west while over the Great Lakes a
deep trough will set up. A shortwave dropping down the Great Lakes
low will buckle the flow over the Upper Midwest and while we will be
dry...we will be slowly moderating in temperature through Tuesday
and perhaps Wednesday as well. All models move the upper ridge east
but only so far as the Rockies which still keeps our area in a deep
northwest flow. By late week the upper ridge moves over the Upper
Midwest but now the Euro brings a system further into the west
coast/Rockies that breaks down the ridge somewhat. While we will be
warmer for the end of the week...there is about a 10 degree
difference in the MOS output for highs between the Euro and the GFS
as a result of this change in the Euro. The Canadian model is still
similar to the GFS. The result of this was that I knocked highs
down several degrees, especially on Friday to account for some
modification to the ridge.
The next chance for precip is still in the Friday timeframe as all
models bring a shortwave across the Plains...the intensity of which
varies greatly. In addition to the upper level feature, a surface
low will develop over the Plains with a frontal boundary extending
somewhere across Missouri or Iowa which will move across the region
through Friday. There is some weak instability with this Friday
system as well and I tried to indicate this with the use of more
convective wording with respect to precip. Showers were indicated
where during times of better instability.
On Sunday a stronger low moves in from the west coast and into the
Plains by Sunday evening. A decent surface low develops with this
system though at this timeframe the models are all over the place
with where these features set up. We`ll likely see widespread
precip develop with this Sunday night through Monday morning. At
this point, temps look warm enough for rain during the day and
likely a mix across at least northern locations at night. We will
need better clarity from the models before defining specific details
on ptype. Temps will at least be spring-like with highs in the
upper 40s north to around 60 south and lows in the 30s and 40s.
&&
.AVIATION.../For the 00Z TAFS through 00Z Monday evening/
Issued at 615 PM CDT Sun Mar 11 2018
Main challenge will be continued stratus overnight and increasing
winds Monday aft 14z. Upper level system pulling out but area of
low level moisture remains trapped w/i the boundary layer. A few
breaks in the MVFR deck showing up near KDSM at 23z but solid
shield of MVFR/at time IFR remains over much of the region. This
will slide southeast through 12-14z Monday...keeping most of the
area within MVFR/IFR overnight. Will likely see improvement 10-12z
at KFOD/KMCW then southeast thereafter. Winds will increase from
the northwest aft 12-14z with mixing gusts to 18-24kts through
near end of period as VFR conditions return. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Ansorge
LONG TERM...FAB
AVIATION...REV
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1049 PM EDT Sun Mar 11 2018
.SYNOPSIS...
A complex surface low will move across our region from the west
overnight and early Monday, bringing widespread precipitation to the
area. As the low moves offshore, colder and drier high pressure will
build to our west late Monday and Tuesday and persist through
midweek. This will result in below normal temperatures and a chance
for additional snow flurries near the North Carolina and Tennessee
border. Temperatures will warm up later in the week.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 1030 PM EDT: The incoming 00Z NAM continues to feature fairly
robust QPF on the northwest side of the passing surface low to our
southeast early Monday. It also has cooler raw model 2-m
temperatures across much of western NC as precipitation rates pick
up Monday morning from the foothills east through piedmont through
18Z. The hazards were already adjusted this evening to make the
Winter Storm Warning countywide across Avery, and the primary
question mark going forward continues to be the potential for
accumulating snow out along the I-40 corridor across the piedmont,
with more snow also mixing in under heavier showers southward along
the I-77 corridor midday. With the forecast trending cooler and
somewhat wetter in these areas, some one-half inch to inch snow
amounts are showing up across parts of Davie County and northern
Alexander County. Since the full 00Z suite is just starting to
arrive, and the latest RAP runs are a bit warmer, will likely defer
to the midnight shift in collaboration with WFO RAH, on any eastward
expansion of the Winter Weather Advisories for Monday.
Otherwise, the latest water vapor imagery shows the deepening closed
system moving southeast across western TN late this evening. The
primary surface low was analyzed just west of the southern
Appalachians across extreme eastern TN, with a secondary low
developing along the Carolina/GA coast. Regional radar returns
continue to blossom overhead, with better rates developing closer to
the upper low off to our west. A cold rain is expected in most
areas, but locations within the advisories/warnings are already at
or near freezing along the higher peaks, so a mixed bag should begin
during the overnight hours, trending toward snow as the surface low
passes to the south and snow levels steadily fall toward daybreak.
Still anticipate some measure of dry slotting arriving from the
southwest through Monday afternoon. This should permit late day
precipitation to pare back to northwest upslope snowfall in the
western mountains by evening.
&&
.SHORT TERM /MONDAY NIGHT THROUGH THURSDAY/...
As of 255 PM EDT Sunday: The upper low from Monday moves east of the
area Monday night but a trough remains over the eastern CONUS
through Thursday. A series of strong short waves drop through the
trough and across the area Monday night and Tuesday night. These
waves will bring periods of NW flow snow to the NC mountains both
nights. There should be around an inch of additional snow for the
favored upslope areas both nights but 2 inches can`t be ruled out.
Windy conditions will continue across the mountains along with below
normal temps through Wednesday night. Despite the wind and cold
temps, any below zero wind chill values should be limited to ridges
above 5000 feet. Temps warm back to near normal for Thursday as
heights begin to rise with the trough axis moving east. However,
windy conditions will continue.
Outside of the mountains expect dry and breezy to windy conditions
through the period. Looks like enough moisture will be associated
with the short waves for some clouds to break containment and spread
out across the foothills and piedmont. However, no precipitation is
expected. Temps show a similar trend to the mountains with below
normal readings until Thursday when they rise to near normal.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
As of 250 PM EDT Sunday: The medium range forecast period
begins Thursday night as latest guidance continues to prog an
evolving unsettled weather pattern for the weekend.
With a northward expanding sfc high pressure over GOM/FL panhandle
into the Carolinas, upper ridge across the eastern half of the US
will continue to propagate eastward and weaken as it does so
Thursday night and throughout the day on Friday. Meanwhile, back to
the west, an upper level disturbance will aid in the development of
a sfc low across the central plains at the end of a week, allowing
for a warm front to extend eastward and just north of the FA through
the weekend, placing the FA essentially in the warm sector. Tapping
into GOM moisture with the gradual return of SW flow, this along
with isentropic lift will increase chances for scattered showers
beginning as early as Friday afternoon across the western portions
of the FA, filling in overnight into Saturday morning, tapering off
just past the forecast period per latest guidance. Would not
entirely rule out an isolated thunderstorm or two as well on
Saturday afternoon given weak instability. Temperatures are expected
to remain around or just above normal through the forecast period.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
AT KCLT: Radar coverage continues to blossom rapidly and rain will
fall through the overnight hours along with IFR visibility and IFR
to LIFR cigs. The main question mark for KCLT is the potential for
snow showers to mix in with the precipitation on Monday. The
deformation zone forcing and steepening upper lapse rates suggest
high enough precipitation rates to mention a RASN mix after 15Z.
Light accumulations at the airfield cannot be ruled out if the
showers get heavy enough 15Z to 18Z. Otherwise, expect steady NE
winds early, becoming gusty N late with cigs improving through MVFR
late in the day on Monday.
Elsewhere: IFR cigs are generally already in place around the region
this evening, and cigs should fall rapidly to LIFR along with IFR
visibility in rain and fog as low pressure approaches from the west.
Snow showers mixing in with the rain will be a concern mainly from
KAVL to KHKY Monday morning, with just a cold rain at the Upstate SC
TAF sites. Cigs will improve from the southwest through MVFR with
some drying through the afternoon hours. Anticipate steady NE winds
across the foothills the first half of the period, becoming
northerly and gusty on Monday. At KAVL, southeast winds early will
toggle NW overnight and become stronger through the day, with G25kt
at times late. LIFR to IFR cigs early will gradually improve through
MVFR throughout Monday afternoon behind the passing shower bands.
Outlook: Improving conditions are expected Monday night into Tuesday
with dry high pressure building in from the northwest. Northwest
flow moisture could keep some clouds in at KAVL from time to time
through mid week.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT Med 65% Med 67% Med 77% High 92%
KGSP Med 72% Med 66% High 82% High 90%
KAVL Med 61% Med 73% High 81% High 90%
KHKY Med 64% Med 65% Med 71% Med 78%
KGMU Med 75% Med 66% High 83% High 92%
KAND Med 78% Med 66% Med 73% 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...Winter Storm Warning until midnight EDT Monday night for
NCZ033-049-050.
Winter Weather Advisory until midnight EDT Monday night for
NCZ048>052.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...RWH
LONG TERM...SGL
AVIATION...HG
Area Forecast Discussion
National Weather Service Wilmington OH
844 PM EDT Sun Mar 11 2018
.SYNOPSIS...
Low pressure will track across the Tennessee Valley tonight into
Monday morning. An upper level trough moving across the Great
Lakes into New England through mid week will bring much below
normal temperatures and scattered showers. A warming trend will
ensue for the end of the week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Surface low pressure over the Tennessee Valley will lift
northeast over the Appalachians through tonight. Precipitation
associated with this has been spreading eastward across southern
Indiana and western/central Kentucky this evening. The high res
models have been slowly trending farther north with the
northern extent of their pcpn and have now come a bit more in
line with the 12Z/18Z synoptic models. As a result, have trended
pops up across our far southern tier of counties through the
early morning hours. Ptype will be an issue as we are still in
the lower 40s along and south of the Ohio River. However, areas
to our west have been wet bulbing with pcpn onset and changing
over to snow fairly quickly. Will therefore allow for a
rain/snow mix initially but then transition over to snow within
the first hour or so. The last couple of runs of the HRRR and
RAP our both bringing close to a quarter of an inch of QPF into
the far southern portions of Owen County, with about a tenth of
an inch of QPF elsewhere across our far southern CWA border.
Some of this may initially fall as rain, but with a faster
changeover to snow expected, have nudged up snow accumulations a
bit across our southern areas. With 1 to locally 2 inches of
snow possible across at least southern portions of Owen County,
have opted to go ahead and issue a winter weather advisory for
them. Elsewhere across our far south, for now will stick with
the SPS with any accums generally an inch or less.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Northern stream short wave will dive south southeast Monday into
Monday night as it carves out an upper trough. This initial
energy will result in scattered showers occurring, mainly in the
afternoon into the evening. At this point, it appears that
temperatures will initially be warm enough for this to be rain,
but any heavier passing convective elements could result in a
mix. And temperatures may cool enough late in the afternoon into
the evening for there to be some snow showers. Higher coverage
of showers will be from west central Ohio into central Ohio.
Activity should diminish by late evening with some clearing into
the overnight hours. Forecast temperatures are near or just a
bit cooler than guidance consensus.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
The long term will be characterized by an upper level trough across
the east coast and ridging over the Mountain West. The GEFS and GEPS
in general shows the lower heights remaining through the work week
with above normal heights progressing east for next weekend.
An upper level low Tuesday morning will be centered over
southeastern Ontario with a potent surface low pressure located off
the east coast. Across Ohio the upper level trough axis will be
centered just off to our west. 850 mb temperatures fall to around 9
degrees C below zero with 1000/850 mb thicknesses forecast to be
around 1285 m. These type of temperatures and thicknesses would
support highs in the mid to upper 30s across the area. The other
concern for Tuesday will be the potential for widespread snow
showers. DGZ lapse rates are around -8 degrees C/ km with more than
sufficient lapse rates, and DGZ RH. The PV anomaly is also
sufficient, but looks to support more cellular development. The main
unknown here is pavement temperatures. For now will leave mention
out of HWO, but Tuesday travelers should check back on the forecast
as we continue to refine.
Tuesday night into Wednesday morning another shortwave will dive
south out of Ontario and move overhead. This will bring one more
reinforcing shot of cold air to the region before the trough axis
begins to modulate. As the trough axis starts to pull east Wednesday
afternoon snow showers will start to come to an end. With this being
said, 850 mb temperatures are forecast to be around 9 degrees C
below zero. Thursday afternoon one more shortwave will dive
southeast out of Ontario and head southeast across eastern Ohio. The
main energy will miss us to the east meaning the warming trend will
start to commence Thursday even as a cold front stalls out across
the Indiana, Ohio, Kentucky border. The latest CMC would support a
slightly further west track of the shortwave or slightly colder
conditions. Either way highs nearing 50 degrees (or near normal)
will be possible Thursday.
Friday, pieces of energy from the upper level low off the west coast
will begin to eject east with heights rising across the region.
There is significant model disagreement here on timing though as the
ECMWF, GFS, and CMC all handle things slightly different. Overall
the GFS appears to be to quick with the upper level low pushing east
while the CMC looks to slow. The old 00z ECMWF splits the
difference. The new 12z ECMWF is completely different and pushes the
front through the entire central United States (which appears to be
an outlier). Saturday into Sunday another wave will push east with a
cold front stalling out again near the Indiana, Ohio, Kentucky
border. Timing is all over the place here. The old 00z ECMWF stalls
the front across the area Friday evening and then keeps it there
through Sunday morning. The GFS stalls the front out Sunday morning,
but quickly lifts it north. The CMC follows closer to the ECMWF. For
now have trended the forecast to the CMC/ ECMWF solutions, but
confidence is low here.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
A low pressure system will lift northeast across the Tennessee
Valley overnight. Precipitation associated with this will
affect areas mainly to the south of the Ohio River this evening
and into the early morning hours. It looks like KCVG/KLUK will
remain on the northern fringe of this. Have left them dry but it
will be tough to rule out a brief rain or snow shower through
the first 6 hours or so of the TAF period. Generally expect just
mid level clouds into the early morning hours, but if KCVG/KLUK
were to get a shower, a brief period of MVFR conditions would
not be out of the question there.
The low will lift off to the northeast later tonight, allowing
for some clearing late tonight into Monday morning. However,
some lower end VFR stratocu will work back in from the
northwest later Monday morning and into the afternoon. This
stratocu may eventually drop down into MVFR category toward he
tail end of the KCVG 30 hour TAF period.
OUTLOOK...MVFR ceilings possible Monday night into Wednesday
morning.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...Winter Weather Advisory until 8 AM EDT Monday for KYZ094.
IN...None.
&&
$$
SYNOPSIS...
NEAR TERM...JGL
SHORT TERM...
LONG TERM...Haines
AVIATION...JGL
Area Forecast Discussion
National Weather Service Melbourne FL
1010 PM EDT Sun Mar 11 2018
.DISCUSSION...
...Fast Moving Showers and a Few Strong Storms Late Tonight Through
Early Monday...
Sufficient heating and low level moisture combined with mesoscale
sea/lake breeze boundaries to produce a few heavy showers late this
afternoon and early evening on the east side of the FL peninsula. A
couple of narrow swaths of beneficial 0.25"-0.50" rains (and no
lightning) occurred across north Lake county, Geneva and the Merritt
Island NWR. This activity has weakened and pushed offshore with
sunset so the remainder of the evening should be rain-free though
quite mild with min temps holding in the mid 60s most areas.
Cold front approaches north Florida late tonight accompanied by an
increase in pre-frontal moisture, a weak mid level vort lobe sliding
east ahead of the main short wave trough, and a large swath of upper
level jet divergence. Expect re-development of precip across
northern sections after midnight, esp during the pre dawn hours.
HRRR and local WRF also indicate an increase in convection moving
onshore SW FL off the Gulf which may affect Martin county after
midnight.
The cold front will move into the northern CWA by mid morning
Monday, sweeping across the central and southern counties by mid to
late afternoon. Highest rain chances early in the day, rapidly
ending from NW to SE through the afternoon, followed by clearing
skies north-central. Maxes in the L-M70s north, U70s south. Strong
west winds will develop behind the front gusting 30-35 mph so a Lake
Wind Advisory looks warranted.
Significant increase in mean layer wind fields forecast for late
tonight/early Monday. Flow looks unidirectional, with 850MB winds
increasing to 30-40KT and an 850-500MB storm motion vector closer
to 45-50KT. However, timing and instability considerations are likely
to mitigate the threat for severe storms, however mean wind fields
support potential for strong gusts in any deeper convection (heavy
rain showers or storms).
&&
.AVIATION...VFR through about 06Z. Potential for some IFR stratus
ahead to form out ahead of the front (through about 10-12Z north,
possibly hanging on a little later central-south. Expect increasing
coverage of showers along with a few storms. Highest chance looks to
start around 09Z @KLEE-KDAB 12Z@KISM-KMCO-KTIX, and 14Z-16Z MLB-SUA.
Have added LLWS (low level wind shear) at MCO/DAB/LEE/SFB/TIX
beginning 07Z due to increase in wind fields just above the boundary
layer.
&&
.MARINE...
Tonight...SW-W winds will increase to around 20KT well offshore late
tonight-early Monday ahead of the strong cold front. However, seas
will be slow to fully respond given the offshore trajectory. So will
continue a Caution headline for the offshore waters overnight.
Monday...(previous) Winds shifting to NW and increasing further 25-
30KT) through late afternoon will bring higher winds/seas (up to 9FT
or so) closer to shore. Started an SCA beyond 20 nautical miles by
mid-morning Monday, with extension into the nearshore water by mid
afternoon, with hazardous boating conditions continuing through
Monday night.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 64 74 42 65 / 60 70 10 0
MCO 66 75 44 68 / 30 70 0 0
MLB 67 76 43 70 / 30 70 10 0
VRB 67 75 44 69 / 30 80 10 0
LEE 65 72 43 67 / 60 70 0 0
SFB 65 75 44 66 / 50 70 0 0
ORL 66 74 46 68 / 40 70 0 0
FPR 66 75 43 70 / 30 80 10 0
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 4 PM Monday to 8 AM EDT Tuesday for
Flagler Beach to Volusia-Brevard County Line 0-20 nm- Sebastian
Inlet to Jupiter Inlet 0-20 nm-Volusia-Brevard County Line to
Sebastian Inlet 0-20 nm.
Small Craft Advisory from 10 AM Monday to 8 AM EDT Tuesday for
Flagler Beach to Volusia-Brevard County Line 20-60 nm-
Sebastian Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard
County Line to Sebastian Inlet 20-60 nm.
$$
Kelly/Weitlich
Area Forecast Discussion
National Weather Service Nashville TN
930 PM CDT Sun Mar 11 2018
.DISCUSSION...
Surface low now moving out of southeastern Middle Tennessee, with
colder air now surging in behind it. At 02z temperatures were
already in the middle to upper 30s over the northwest, with the
edge of a Kentucky snow band now just starting to nose into the
Land Between the Lakes area. Latest HRRR snowfall prediction for
overnight and Monday morning, is closely aligned with ongoing
forecast and placement of snow advisory area. Still looks like
temperatures will cool to the freezing mark in the advisory area
by late tonight, allowing for up to 2 inches of accumulation.
Latest short-term model runs suggest that snow area will linger a
tad longer over our eastern areas between 12z and 15z Monday, and
have increased PoPs to likely for those areas, before tapering
them back to chance PoPs between 15z and 18z. Eastern areas will
be dry slotted until late tonight, which will give midnight shift
a chance to gauge our ongoing snow advisory area and determine if
additional counties might need to be added along the southern and
eastern fringe. However, as mentioned earlier, ongoing forecast
still looks pretty reasonable.
Expect a messy early morning commute on Monday in the advisory
area. However, skies clear quickly behind the departing snow, and
temperatures will rapidly recover into the 40s, allowing for some
pretty quick melting of this late season shot of snow.
Have updated grids to more closely agree with latest trends, but
ongoing forecast remains pretty much the same.
&&
.AVIATION...
00Z TAF DISCUSSION.
A low pressure area will pass east of the Mid-State by 06z, with
gusty north winds and a transitioning precipitation pattern
developing from west to east overnight. Rain is expected to
change to a mix of rain and snow, as colder air pushes in from the
north, on the back side of the low. It`s possible that late
tonight and early Monday, precipitation will change to all snow,
before the precipitation finally ends and skies clear between 14z
and 16z. However,a batch of stratocumulus is forecast to sweep in
from the northwest during the mid-to-late afternoon on Monday.
IFR conditions will prevail at CKV, BNA and MQY through about
15z. MVFR conditions at CSV will deteriorate to IFR later tonight
and continue through about 16z. Skies clear from west to east
during the mid-to-late morning on Monday, but then you can expect
a broken deck of stratocumulus to bring VFR ceilings to area
terminals during the mid-to-late afternoon.
Frequent wind gusts to 22 kts are expected through most of the
forecast period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 33 49 31 47 28 / 90 10 0 0 0
Clarksville 30 48 29 45 26 / 90 0 0 0 0
Crossville 31 43 27 40 22 / 90 60 10 0 10
Columbia 32 49 30 48 27 / 80 10 0 0 0
Lawrenceburg 33 49 29 48 26 / 70 20 0 0 0
Waverly 31 49 30 47 27 / 80 0 0 0 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 7 AM CDT Monday for Cheatham-Clay-
Davidson-Dickson-Houston-Humphreys-Jackson-Macon-Montgomery-
Overton-Pickett-Robertson-Smith-Stewart-Sumner-Trousdale-Wilson.
&&
$$
DISCUSSION......19
AVIATION........08