Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/09/19
Area Forecast Discussion
National Weather Service Denver/Boulder CO
855 PM MST Fri Mar 8 2019
.UPDATE...
Issued at 827 PM MST Fri Mar 8 2019
Overall the forecast appears to be on track for this evening. We
made some minor adjustments to the pops based off the radar this
evening. Most of the precipitation so far has fallen as rainfall
but should start to see it mix or change over the snow is it
continues to track east. The main line of precipitation is fairly
progressive, and is moving across the Denver area at this time.
Could see a brief period of moderate rain showers, with a mix of
snow. There could be enough to produce a quick of inch of snow or
slush is it passes by. Not much lightning generated by this
except along the WY/CO border earlier this evening. Still a chance
over the next hour or so. This is the main band for the plains
this evening, anything after that should be light and brief. Gusty
downslope winds will develop in the foothills overnight. No
changes to the current highlights in effect for the mountains and
foothills. Westerly winds will gradually increase across the
northeast plains tonight into Saturday morning, then strongest
from around 10 am to 4 pm Saturday.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 224 PM MST Fri Mar 8 2019
Very active weather pattern over the next 12 hours. Water vapor
satellite imagery showing a short wave trough spinning over Utah.
This trough will track east across Colorado tonight. Lift ahead of
this trough will continue to produce widespread snow across the
mountains of Colorado. In addition to this, the airmass is
unstable with surface based CAPE off the RAP up to 400 J/kg.
Because of the lift and instability, showers and a few
thunderstorms will likely produce areas of heavy snowfall.
Snowfall rates will top 2 inches an hour for a short time under to
strongest convection. Mountain roads will become snowpacked and
slippery by sunset. Convection then rolls off the foothills after
00Z. The airmass should be warm enough for mainly rain. However,
under the stronger convection, snow and ice pellets will be
possible. If this occurs, expect accumulation to be less than an
inch. Over the far northeast corner of Colorado, ahead of the
convection, drizzle will be possible. Temperatures should be warm
enough that it would not be freezing drizzle.
Strongest mountain stable layer occurs 12Z to 18Z Saturday. This
combined with subsidence behind the exiting system and strong flow
aloft will result in very windy conditions for the higher
mountains and Front Range Foothills. Will upgrade the High Wind
Watch to a Warning. Will need a decent mountain wave to form to
help accelerate winds down the foothills. Models show a mountain
wave forming late tonight and Saturday morning. Will it be enough
to help winds reach 75mph? Tough call, so confidence on Warning is
on the low side. Windy conditions will prevail across northeast
Colorado as well Saturday. Right now, appears gust to 50 mph will
be possible, so no High Wind Warning at this time.
There will be enough moisture embedded in the strong flow aloft
to produce orographic snow showers over the mountains late tonight
and Saturday. Additional snowfall will be light for the mountains
Saturday. Most locations will see little if any snowfall,
orographic favored areas may see up to 2 inches of snow.
.LONG TERM...(Saturday night through Friday)
Issued at 224 PM MST Fri Mar 8 2019
For Saturday night, the winds will be diminishing across the far
northeast plains as the storm system rapidly shifts into the
upper Midwest. There will areas of continued light snow in the
mountains, but amounts will be minimal.
For Sunday and Sunday night, a more tranquil day across Colorado
as high pressure ridge builds into the state. The flow aloft will
be shifting back more southwest in response to the next Pacific
system which will be digging down into Baja by early next week.
There will still be some snow showers in the mountains, but
moisture trajectories look to keep most of the showers over
northwest Colorado, including portions of Jackson county and
lesser snow chances further south along the I70 corridor. The
plains will be dry and mild on Sunday but should see an influx of
low level moisture Sunday night into Monday morning. A developing
Denver cyclone may also result in low clouds and fog moving into
the Denver area as well. Deeper subtropical moisture riding along
a jet streak will also be advecting into the region during the
day on Monday in advance of the strong upper low over Baja. Expect
scattered showers to develop across the plains, especially
southern sections over the Palmer Divide and Lincoln county.
The main question through the middle of next week is the track
of the Baja low as it moves northeast through Wednesday. There
is a bit better continuity in model track again today with the low
moving into southeast Colorado late Tuesday and early Wednesday
before moving it into eastern Nebraska by late Wednesday. The
European/Canadian solutions show this the most, while the GFS
track is still a bit further east and south. With this overall
track, there is a threat of heavy snow somewhere over eastern
Colorado early next week especially if European/Canadian verifies.
For Thursday and Friday, there will still be a fair amount of
troughiness over the region for a continued chance of snow
showers over the mountains. The plains will generally be dry for
later in the week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 827 PM MST Fri Mar 8 2019
Main band of showers moving across the terminals at this time.
Rain or a rain/snow mix will produce MVFR cigs and vsby
restrictions through 05z then a steady improvement thereafter.
Heavier showers activity could produce ice pellets and/or snow.
If any accumulations were to occur they will be light. Gusty
west/northwest winds to 25-30 kts also possible. That will
decrease as well for from around 05-08z.
VFR the rest of the period. On Saturday, partly cloudy to mostly
sunny skies will prevail Saturday. Gusty northwest winds to 30
knots will be possible after 15Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from midnight tonight to noon MST Saturday for
COZ035-036.
Winter Storm Warning until 6 AM MST Saturday for COZ031-033-034.
&&
$$
UPDATE...Cooper
SHORT TERM...Meier
LONG TERM...Entrekin
AVIATION...Cooper
Area Forecast Discussion...Updated
National Weather Service Billings MT
900 PM MST Fri Mar 8 2019
.UPDATE...
Satellite and radar continue to show the shortwave tracking
through northeast Wyoming and southeast Montana. The RAP continues
to have the heaviest snowfall across mainly Powder River and
Carter counties, in the warning area. Webcams show a similar
trend. The highlight look in good shape. Reimer
&&
.SHORT TERM...valid for Sat and Sun...
Current satellite imagery shows a shortwave lifting thru the great
basin in SW flow aloft, and a weak cut off low over the PacNW.
Diffluence aloft is increasing in response to the energy to our
south, and latest mid level analyses show backing winds. Precip is
moving into northern WY as upslope flow continues to deepen. We
have seen areas of light snow today, mainly in our west from
Livingston to Judith Gap and in the east close to the Dakotas
border, but the main event is beginning this evening.
Have made no changes to our current winter highlights. Strongest
ascent will clip far southeast MT, and this is where the heaviest
snow will fall (warnings are in effect for Powder River and Carter
counties). Forecast amounts of 5-9 inches are in line with
consensus model QPF fields, and the Garcia method of using mixing
ratios on an isentropic surface. So there is some confidence here.
That being said, latest HRRR and RAP runs have shifted the 700mb
low a bit further to the NW, which shifts the axis of heavier snow
a bit further into our cwa, to include eastern Sheridan to Fallon
counties. Have adjusted amounts up slightly to accommodate a
slight shift. Places like Broadus, Ekalaka and Alzada will see a
good dose of snow tonight thru Saturday morning. Places like
Sheridan, Lame Deer and Baker will see a good snowfall but in the
3-6 inch range. Further west, the ascent is much weaker but will
linger due to weak but slow-moving low to our west. A few inches
of snow are possible along our western foothills. As for Billings,
we are largely between the two areas of forcing and will see less
accumulation. It will snow some here in the city, but have
lowered forecast amounts to 1-2 inches. Even less snow (under an
inch if any) will fall along the Musselshell River. We will dry
out by Saturday afternoon and early evening as the shortwave
shifts east. We will see a split NW flow and dry conditions
Saturday night through Sunday night.
Temperatures will remain below normal with highs ranging from the
mid 20s to mid 30s the next two days, coldest in our east.
JKL
.LONG TERM...valid for Mon...Tue...Wed...Thu...Fri...
The forecast area will be between systems Monday into Tuesday. A
split flow aloft will be over the forecast area along with some
weak ridging and subsidence. This will result in dry conditions
and mild temperatures prevailing. Monday and Tuesday will see the
warmest temperatures of the week with middle 30s to lower 40s
common, which continues to be below normal.
The next chance for snow will be arriving Wednesday and Thursday
as another upper low will move out of the four corners region.
This will, along with an associated surface low, intensify and
move into the central plains region. Models differ in the strength
of the upper low but do agree on keeping the heaviest of the
precipitation east of our forecast area across Nebraska and South
Dakota. However, at the same time, another surface low will move
southeast across Idaho with general troughiness over the Northern
Rockies. This will result in temperatures cooling back into the
20s and 30s along with a good chance of snow. Timing is still too
far out for details so monitor the forecast as we go through this
weekend into early next week. Hooley
&&
.AVIATION...
Snow will continue with IFR conditions overnight over southeast
MT and north central WY. Over south central MT, MVFR conditions
with snow will improve later tonight to VFR. Mountains will be
obscured. Winds will be gusty in the KSHR area. RMS
&&
.PRELIMINARY POINT TEMP/POPS...
Sat Sun Mon Tue Wed Thu Fri
-----------------------------------------------------------
BIL 020/031 010/033 014/038 020/041 020/035 021/032 013/031
85/S 00/U 00/U 01/U 23/S 31/E 00/U
LVM 015/027 005/030 008/036 015/037 016/029 014/027 008/029
96/S 00/U 00/U 02/S 33/S 21/B 10/B
HDN 017/031 004/032 006/037 013/040 015/034 019/032 008/030
95/S 00/U 00/U 01/U 24/S 31/E 10/B
MLS 018/025 004/027 006/033 013/036 016/031 020/029 009/026
96/S 00/U 00/U 00/B 13/S 32/S 10/B
4BQ 019/029 006/031 007/038 017/040 017/033 019/030 011/029
+8/S 10/B 00/U 01/B 14/S 53/S 10/B
BHK 018/025 006/026 006/033 017/036 018/029 019/027 010/024
+9/S 10/B 00/U 01/B 13/S 63/S 10/B
SHR 018/030 007/033 010/039 018/043 020/034 019/030 011/030
97/S 00/U 00/U 01/B 24/S 42/S 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect until 11 AM MST Saturday
FOR ZONES 30>33-35-38-57-58.
Winter Weather Advisory in effect until 5 PM MST Saturday FOR
ZONES 34-39>41-56-64>66.
Winter Storm Warning in effect until 5 PM MST Saturday FOR
ZONES 36-37.
WY...Winter Weather Advisory in effect until 11 AM MST Saturday
FOR ZONE 99.
Winter Weather Advisory in effect until 5 PM MST Saturday FOR
ZONE 98.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
1014 PM EST Fri Mar 8 2019
.SYNOPSIS...
A frontal boundary over the northern Midlands will slowly
sink southward into Saturday resulting in showers. As a strong
low pressure system develops in the upper Midwest over the
weekend, a cold front will approach the Carolinas and Georgia.
Scattered showers and a few thunderstorms are expected ahead of
the front by late Sunday. The front may stall near the area into
early next week. A wide range of temperatures will occur
Saturday as weak wedge conditions develop in the South Carolina
Piedmont north of the front. Above normal temperatures are
expected late in the weekend ahead of the next cold front.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
An east-west oriented front will extend through the central or
south part of the forecast area tonight. There will be a series
of mid-level shortwave troughs in the flat flow. The models
indicate continued isentropic lift supporting rain. The rain
should be mainly in the north section where deeper moisture has
overspread the area. Radar trends support a considerable
gradient in pops from north to south. Trends support mainly
light rainfall amounts of one quarter of an inch or less
late tonight. The RAP keeps negative showalter index values
west of the forecast area overnight. The trend has been for
lightning to dissipate as it moves eastward and toward the
forecast area from north-central Georgia. We forecasted just
isolated thunderstorms in the west part overnight.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Saturday...Frontal boundary remains across the area in the
morning then will lift slowly north. In-situ wedge across the
north Midlands most of the day will keep temperatures down a
bit. Weak isentropic lift possibly increasing across the north
Midlands should result in a few scattered showers mainly in the
morning. There appears to be a shortwave trough moving through
the area in the afternoon and with diurnal heating there may be
some lingering showers although the front appears to be north
of the area. Upper-level ridging and drier air should limit
showers in the afternoon as the front moves north of the area.
Moisture may be a limiting factor but precipitable water near
1.25 inches. Will continue slight chance pops across the western
Midlands late Saturday afternoon into evening. Blended
temperature guidance appears on track with above normal
temperatures over much of the region as warm front moves slowly
north. Tricky temperatures forecast north Midlands where in-situ
wedge may be slow to erode.
Sunday...little change from previous forecast. A deep mature
cyclone will lift northeastward from the Central Plains into the
Great Lakes region Saturday night and then into eastern Canada
Sunday pushing a cold front into the forecast area by the
evening. There are some ingredient in place for convection but
severe weather threat appears limited as the greatest moisture
flux and wind shear shift through the area Sunday morning and
out of the region by the time the axis of highest precipitable
water values and instability arrive with the front late in the
afternoon. Most of the upper dynamics will be well north of the
forecast area as well leaving the frontal boundary as the
primary forcing element. Will continue to carry high chance to
low likely pops with the highest pops in the southeastern
portion of the forecast area during the evening hours. QPF
across the north Midlands appears to be more limited with 12z
guidance. Temperatures well above normal Sunday afternoon ahead
of the front...approaching 80 degrees in the southeast
Midlands/CSRA.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Frontal boundary appears to be well south of the area Monday
resulting in a dry forecast through at least midweek as surface
and highly amplified upper ridge builds over the eastern CONUS.
Another deep low moves into the central Plains Wednesday. Upper
ridge axis moves east of the area Thursday which will allow
some shortwave troughs to move into the area. Moisture may be
increasing ahead of an approaching cold front late in the week.
Temperatures during this period will be near to above normal.
Temps should be in the 70s to near 80 Friday ahead of the
front.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Shallow surface frontal boundary stalled NE-SW from KFLO-KXNO-
KDNL. Wedge conditions developing over the Upstate and Piedmont
to the north. Radar and satellite support 2 upper troughs with
deeper moisture and shower activity...one sinking ESE through
Central SC right now and another upstream in N GA. Both of these
will develop showers and tempo MVFR conditions within the TAF
period, with heaviest precipitation expected at KCAE/KCUB.
Difficult cig/vis forecast as front is expected to wave slightly
north and south in response to each trough approach/passage
with deepest moisture and solid IFR conditions north of the
front. Used a combination of LAMP and HRRR model guidance to
indicate moderate confidence in MVFR conditions with showers and
IFR conditions at KCAE/KCUB after second trough passage...with
improvement after 17-21Z tomorrow as front returns north as a
warm front. MVFR expected at AGS/DNL/OGB as the front remains
just overhead or slightly to the north...with earlier
improvement after 18Z.
EXTENDED AVIATION OUTLOOK... Flight restrictions again possibly
returning Saturday night into Sunday. Showers and isolated
strong thunderstorms possible Sunday afternoon/evening with
another cold front. High pressure builds in slowly Monday
through Wednesday with no expected restrictions.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99
Area Forecast Discussion
National Weather Service Wilmington NC
940 PM EST Fri Mar 8 2019
.SYNOPSIS...
A weak cold front will drop south and stall over the area overnight
before returning north as a warm front by Sunday. A cold front
will cross the region late Sunday, possibly accompanied by
thunderstorms. Dry weather then returns under high pressure
early next week.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
As of 930 PM Friday...Rain has continued to spread farther south
than any model thought possible this evening. Surface
observations show rain has reached the ground as far south as
Kingstree, Marion, and Myrtle Beach. High radar reflectivity
values in the Lumberton area earlier were partially the result
of bright-banding as the radar beam encountered the freezing/
melting level only 6000 feet aloft.
Although I`m still not excited about any model`s initialization
of the current frontal position or rainfall distribution, the
01z RAP isn`t bad and correctly paints rain farther south than
any other model guidance. It shows our area entering a relative
lull in rainfall rates and coverage now through about midnight,
followed by a second wave of more concentrated rain north of
Kingstree, Conway, and Myrtle Beach early Saturday morning.
This second wave should then begin to diminish before daybreak
Saturday leaving cloudy skies in its wake.
Changes with this update centered on adjusting the frontal
position southward now and through the night to match
observations of NE winds in the Myrtle Beach/Marion/Florence
area, and the aforementioned PoP/Wx adjustments. Discussion from
630 PM follows...
A solid area of rain extends from Burgaw westward across
Elizabethtown, Lumberton, and Bennettsville, then farther west
across Charlotte and into upstate South Carolina. This appears
to be associated with isentropic lift centered near the 300K
theta surface, approximately 9000 feet AGL. The majority of
models don`t show the lift quite far enough south to account for
the current positioning of echoes on radar, so I`ve had to
manually adjust the forecast slightly to introduce better rain
chances across our northern South Carolina counties and into the
Wilmington area for this evening.
Hourly temperatures have been adjusted to reflect a large area
of 60+ degree readings lingering for most areas south of the
east-west front extending from just north of Florence,
Whiteville and Wilmington. Overall synoptic thinking for
overnight has changed little with the progression of this front
as it is expected to slowly sink farther south across South
Carolina. Discussion from 300 PM follows...
Latest radar imagery showed a line of rain showers moving into
the forecast area just to the west of the I-95 corridor during
the early afternoon ahead of a weak front that is pushing into
the southeast portions of the CONUS. Temperatures across the
region ranged from 64 near Whiteville to 57 near Maxton, with
other temperatures in the upper 50s and lower 60s.
Models prog the approaching cold front to push through the region
staring this afternoon and early evening past the I-95 corridor on a
line from Burgaw to Florence, and eventually pushing to North
Carolina coastal locations by late this evening and overnight.
South Carolina coastal locations are not anticipated to receive very
much in the way of new precipitation tonight.
Front will stall across the area Saturday, but latest projections
are fairly quiet as to expected precipitation. Some scattered rain
showers will be lingering mainly in North Carolina along the stalled
boundary, but Saturday afternoon should be dry with mostly cloudy
skies. High temperatures will vary Saturday due to orientation of
the frontal boundary, ranging from the upper 50s in North Carolina
to the low 70s for inland South Carolina.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...Initially south to southwest flow at low
levels and a deep westerly flow aloft will exist, with moisture
mainly confined below 10 ft and some upper level moisture
through much of Sunday. Therefore, expect some clouds around on
Sunday, but the best moisture and pcp chances will come heading
in the eve. Pcp water will reach 1.5 inches just ahead of the
cold front, and best mid to upper level support comes together
late Sun eve as shortwave pushes cold front through the area.
Overall, does not look like atmosphere will be conducive for
severe weather, but an isolated damaging wind gust is possible.
Expect very warm temps on Sun, reaching well into the 70s with
lows in the 50s Sun night.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...High pressure will build in behind cold
front through Mon but some lingering moisture will remain in the
mid to upper levels through Mon as ridge to the south holds it
up a bit. Expect seasonable weather through mid week with plenty
of sunshine for the most part, as ridge builds up from the
south and high pressure migrates across the northeast. As ridge
becomes more amplified up the Southeast coast through mid week,
some high clouds may spill over the ridge into the area, so can
not rule out clouds at times, but this will also help to warm up
the air mass, especially Thurs into Fri as WAA occurs with
southerly return flow as high pressure shifts off the coast and
farther east. Chance of rain will increase heading into Fri and the
weekend as cold front approaches from the west. Warm temps on
Mon will get knocked back down toward climo Tues and Wed and the
warm again Thurs into Fri.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 00Z...VFR ceilings as a stalled frontal boundary begins to
move to the south overnight. Showers will develop and move west to
east along the boundary throughout the period. By morning, a stratus
event is likely as the front stalls to the south of the Myrtles and
a high pressure system to the NE brings IFR conditions to all
terminals. High confidence in IFR at the inland terminals, but
coastal terminals may see the influence of the warm ocean water,
possible lifting IFR to MVFR or VFR. Shower chances will continue
throughout the day on Saturday, but decrease after morning. Toward
the end of the period, the front will get a push from the south and
this should provide clearing from south to north across the area
with VFR returning ahead of a cold front on Sunday.
Extended Outlook...Possible MVFR/IFR from clouds and showers
associated with a frontal boundary in the area Sunday into Mon. VFR
Tues & Wed.
&&
.MARINE...
As of 930 PM Friday...The front has slid south the coast to
Myrtle Beach where northeast winds are now being reported.
The front shouldn`t move significantly farther south, and I
actually expect winds to maintain a southerly component in the
Winyah Bay/Georgetown area overnight. Seas have begun to build
by 0.5 to 1.0 feet over the past several hours due to swell
arriving from a large area of stronger winds well offshore.
Discussion from 630 PM follows...
Winds and seas remain benign this evening as a weak front
slowly settles south toward Cape Fear. This should eventually
make it down to the Grand Strand area late tonight. Southerly
winds will shift north to northeasterly as the front passes by,
with speeds generally 10 kt or less. Buoy- reported waves are
currently only 1.5 to 2.5 feet across the area, but should build
by about a foot overnight due to stronger winds developing well
offshore. Discussion from 300 PM follows...
Main concern is the possibility of marine fog offshore Saturday
afternoon into Saturday night.
Quiet conditions offshore with waves between 2 and 4 feet through
Saturday night. Mainly onshore winds up to 10 kts can be expected
as a frontal boundary approaches, but does not quite cross the
offshore waters. An occasional gust to 15 mph could occur tonight
and Saturday afternoon.
Winds will increase out of the S-SW through Sunday, ahead of an
approaching cold front. WNA model continues to keep winds and
seas just below SCA thresholds, but will be close. Northerly
flow will develop early Mon as high pressure builds in behind
cold front and will pick up slightly in NE push on Tues. The
high will migrate eastward but remain north of the waters
through mid week with an on shore flow developing on Wed before
winds come around to the S by Thurs. Seas up to 4 to 5 ft Sun
evening will trend downward on Mon. Should see only a slight bump
up in seas on Tues and again on Wed in on shore flow, but
overall expect seas in the 2 to 4 ft range between Mon aftn and
Thurs.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MCK
NEAR TERM...TRA/MCK
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...21
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
958 PM EST Fri Mar 8 2019
.SYNOPSIS...
Mostly cloudy conditions are expected tonight behind a wave of
low pressure. Showers and possibly thunderstorms will accompany
strong low pressure Saturday and Saturday night, along with
windy conditions lasting through Sunday behind a cold front.
High pressure is forecast to provide dry weather Monday and
Tuesday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
A sharp line has been drawn across the ILN CWA tonight with
regards to cloud cover, with stratus remaining in place across
the southern half, and skies becoming basically clear across the
northern half. A quicker erosion of this cloud deck has slowed
over the past few hours, but looking at GOES-E nighttime
microphysics RGB imagery, it does still appear that a slow
erosion is ongoing. Thus, some continued expansion of the
clearing is expected over the next several hours, before clouds
likely begin to expand again closer to morning. At some point,
high clouds will also begin to spill over the forecast area.
The most difficult part of the forecast tonight is with regards
to fog, as the clearing does present the possibility that some
fog could develop in the northern half of the forecast area.
While SREF probabilities have continued to indicate this
possibility, LAMP guidance and HRRR visibility projections have
not been as robust with fog development. In addition, winds are
expected to begin a gradual increase after 06Z. For this reason,
fog was kept out of the grids -- though some MVFR-type
restrictions to visibility might still be possible.
Where the clearing has developed, temperatures are falling at a
quicker rate than previously forecast, so some reductions were
made to the min temp grids in the northern half of the forecast
area.
Looking into tomorrow, the overall thinking regarding the
forecast has not changed too much tonight. Some adjustments
were made to the grids to delay the onset of precipitation,
which looks like it will not be enveloping the Cincinnati area
until about 18Z.
Previous discussion >
Wave of low pressure producing light precip is moving east. This
is leaving the ILN area in a weak easterly flow in the
circulation around high pressure centered over the Eastern Great
Lakes. Little mixing during the evening and early in the
overnight hours should allow clouds to persist under a low level
inversion, and patchy fog may form. Later tonight, winds and
mixing will begin to increase in the tightening pressure
gradient ahead of a warm front developing in front of deepening
low pressure. This should allow fog to dissipate, and clouds
should show a decreasing trend, especially across northern
counties farther from the warm front. Cloud cover will help
temperatures remain much higher than in recent nights, with lows
forecast to range from the upper 20s north up to the mid 30s
south.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Deep low pressure will be traveling across Iowa on Saturday,
before crossing Lake Michigan Saturday night. There will be very
strong moisture transport and lift on a 70 knot 850 mb jet ahead
the low, and a warm front will provide added convergence that
will enhance shower development. Also may observe some
thunderstorms forming in elevated instability. With showers
overspreading the area Saturday and continuing into Saturday
night, around an inch of rain falling on wet soils may lead to
isolated high water issues.
Another problem will be strong winds resulting from the tight
pressure gradient around the low. South winds could gust to 30
knots by Saturday evening, with gusts in the low 30s possible
Saturday night as winds shift to a more westerly direction in
the vicinity of a cold front trailing the low.
For the first time in several days, temperatures will rise above
normal in most locations due to warm advection on the southerly
flow, with highs ranging from the mid 40s north to the mid and
upper 50s south.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
For Sunday into Sunday night. low pressure and mid level energy will
continue to move away to the northeast into Canada. It will remain
breezy to windy with the highest wind gusts approaching 40 to 45 mph
in the northwest zones with 25 to 35 mph elsewhere. Winds should
diminish Sunday night as the pressure gradient relaxes and the
mixing depth shrinks with diurnal cooling. Skies will range from
partly cloudy south to mostly cloudy north in a glancing blow of
CAA. Highs on Sunday will range from the lower 40s northwest to the
upper 50s southeast. Lows Sunday night will range from the upper 20s
northwest to the mid 30s southeast.
High pressure will build south into the region Monday into Monday
night, and then it will push east of the area on Tuesday. Mostly
sunny skies are expected Monday and Tuesday with mainly clear skies
Monday night. Temperatures will average a little bit below normal.
A highly amplified upper level flow pattern is forecast to develop
across the CONUS mid to late next week. A mid level ridge will
eventually be replaced by a shearing mid level trough. This pattern
will be slow to develop and move through the region due to its
amplification, and as such a, cold front doesn`t push through the
area until Thursday night/Friday. The chances of showers will
increase through the period. The first likelihood will be Wednesday
night into Thursday in a zone of strong, moist ascent associated
with a LLJ. Another chance will increase once again Thursday night
into Friday morning with the passage of the cold front. Temperatures
will warm into the 60s by Thursday ahead of the front, then drop
back down into the 40s and 50s in the wake of the front on Friday.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Precipitation has ended across the area for the night, but some
persisting MVFR/IFR ceilings remain in place, especially at the
KCVG/KLUK/KILN airports. Some brief MVFR ceilings may be
possible at KDAY/KCMH/KLCK as well. These clouds should break up
to some degree tonight, allowing for some periods of VFR
ceilings even at the Cincinnati airports. However, there is also
a chance of some MVFR fog development as well, particularly from
about 06Z-13Z.
On Saturday, winds will shift to the southeast and begin to pick
up in intensity, with some gusts to around 20 knots possible by
18Z. Clouds will gradually thicken, with the greatest chance for
MVFR ceilings during the morning once again at the Cincinnati
airports.
Chances for showers and embedded thunderstorms will increase at
the end of the TAF period, especially heading into Saturday
evening. LLWS is also expected during the evening.
OUTLOOK...MVFR/IFR conditions are expected with rain and
thunderstorms on Saturday night, along with gusty winds. MVFR
conditions are possible on Sunday, along with gusty winds.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Coniglio
NEAR TERM...Coniglio/Hatzos
SHORT TERM...Coniglio
LONG TERM...Hickman
AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Key West FL
907 PM EST Fri Mar 8 2019
.DISCUSSION...In the middle and upper levels(700-200 mb), latest
available satellite imagery overlaid with model streamline
analysis depict the axis of a developing full latitudinal
negatively tilted trough across the Western CONUS with axis from
the Bitteroots SSW to Southern New Mexico. Conversely and
downstream of that the axis of a ridge is oriented from the
Western Gulf of Mexico northwards to Western Ontario. South
Florida and the Keys are beneath the eastern periphery if the
approaching ridge axis.
At the surface and in the lower to mid levels(Surface to 700 mb),
latest available marine and land surface observations and analysis
detail the center of a 1030 mb surface anticyclone parked over the
Western Atlantic near 35N 70W. South Florida and the Keys lie
beneath the southwestern periphery of the ridging. The 00Z evening
sounding illustrated just gentle to moderate mostly east winds
just off the surface to about 825 mb, with a 2 degree C inversion
from about 835 to 810 mb, and the column was still dry with PWAT
only at .98 inches.
.CURRENTLY...As of 800 pm, skies are mostly clear across the Keys
Island Chain and surrounding waters. Radar does detect a weak band
of light showers moving slowly northwest towards the Ocean Reef
and Southeastern Dade County, with false returns elsewhere.
Temperatures across the islands are in the middle 70s with
dewpoints in the middle 60s. C-man stations along the Florida Reef
are recording east winds between 10 and 15 knots, with islands
sensors mainly east near 10 mph.
.SHORT TERM...Overnight, latest available forecast soundings
indicate that PWAT should remain near one inch overnight. Surface
ridging should remain in place from near 35N 70W southwest to
South Georgia. Since a few showers are presently in close
proximity to the Upper Keys, and the latest HRRR hints a few
showers could move over the Middle Keys towards daybreak, will
maintain a dime pop overnight, but any of these will be very brief
and sparse. Low temperatures should only fall into the lower 70s
as winds should remain mostly east. The ongoing forecast is on
track so no changes on this cycle.
&&
.MARINE...Overnight, Gentle to moderate breezes are expected
overnight, with now headlines or advisories anticipated. Winds
near 15 knots will be found out in the Florida Straits and 10 to
15 knots elsewhere.
&&
.AVIATION...VFR conditions expected at both the KEYW and KMTH
island terminals. Winds will be from around 100 degrees aoa 8-10
knots with a few gusts.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...Futterman
Aviation/Nowcasts....Futterman
Upper Air/Data Collection......SD
Visit us on the web at weather.gov/key
Follow us on Facebook and Twitter at:
www.facebook.com/nwskeywest
www.twitter.com/nwskeywest
Updated for 00Z Aviation Forecast Discussion below.
&&
.PREV DISCUSSION... /issued 334 PM CST Fri Mar 8 2019/
DISCUSSION...
A warm front remains draped across the Mid-South this afternoon.
The front currently stretches from Forrest City to Decaturville.
North of the front, temperatures are in the mid 40s to mid 50s
with patchy showers and areas of fog. South of the front,
temperatures are in the upper 50s to upper 60s with patchy
showers. The front is forecast to shift slightly to the south by
00Z. This will turn Memphis and the rest of the West Tennessee
winds to the northeast. The front will begin lifting back to the
north after midnight. Patchy showers will continue to be possible
across the CWA. In addition, fog will continue to occur north of
the front. The fog may become dense and a Dense Fog Advisory may
become necessary as Little Rock is already sitting at 1/8th of a
mile as it sits just north of the front. This may happen at more
sites after sunset.
After midnight, the warm front will begin lifting to the north as
a potent upper trof digs into the Southern Plains. Several CAM
models show thunderstorms blossoming along the warm front just
before 12Z. These thunderstorms will be elevated in nature but
will be capable of producing large hail. Threat area will be for
locations along and north of Interstate 40.
As the warm front surges north by 15Z. A second round of
thunderstorm activity will begin to push in from the west ahead of
a pre-frontal trof. This activity will quickly push east into
Middle Tennessee by midday as a third round of thunderstorm
activity will develop along the cold front. This activity will
push across the CWA during the late afternoon into the early
afternoon hours. This third round of activity is the one of most
concern as it will occur with the best instability. There have
been concerns that the potent shortwave would lift off to the
northeast before this convection would develop. The latest 18Z NAM
shows that the shortwave will be passing through the region just
as these thunderstorms will be developing. The Enhanced Risk has
been pushed to the north to align with the stronger forcing for
ascent than the previous DAY 2 issued early this morning. Greatest area
of concern for severe thunderstorms with the possibility of
tornadoes will be across Northeast Arkansas, the Missouri Bootheel
into Northwest Tennessee. South of this area, there remains
questions on how far removed from the forcing will the
thunderstorms still be able to become severe. The 12Z NSSL WRF
and 12Z HRRR show a vigorous line tracking across North
Mississippi while other CAM models show limited development south
of Interstate 40. Thus a lot of questions remain about tomorrow
and a lot it just comes down to timing of the shortwave. Stay
tuned for forecasts updates with the latest information.
Besides the threat for severe thunderstorms, gusty southerly winds
will occur across the Mid-South by mid-morning. A Wind Advisory
may be needed across much of the Mid-South.
High pressure will build into the region Sunday into early next
week. A few upper level disturbances will move through the zonal
flow producing small light rain chances across North Mississippi
and East Central Arkansas at times. After a warm day on Saturday,
temperatures will return with highs in the 50s for much of the
area.
Another potent upper trof will approach the Mid-South by
Wednesday. The ECMWF continues to be much slower with the
progression of the associated cold front than the GFS and
Canadian. This would result in quite a bit of rain falling over
the Mid-South during the Wednesday Night through Thursday Night
time frame. This would increase the risk for flooding with an
already saturated ground. Severe weather chances with this system
look limited at this time as the SFC low will occlude as the front
pushes into the area and will pinch off the instability. Stay
tuned.
KRM
&&
.AVIATION...
00Z TAFs
23Z surface analysis showed a stationary front just south of MEM,
near OLV, with modified marine air immediately south. Short range
guidance from RAP, HRRR, NAM-3km depict this surface front dropping
slightly south through the MEM inbound push this evening, then
pushing quickly north by 10Z or so. IFR will be likely to the
north of the front.
TS chances continue this evening and overnight, but likelihood
too low for mention. TS chances increase after 12Z from the west,
with the approach of pre-frontal surface trof and stronger support
aloft. Will likely see a lull in TS activity once this pre-frontal
trof lifts east, and winds veer to the southwest late morning / early
afternoon. During this lull, low level jet will be strong, varying
from 50 to as much as 70 KTs late morning through midafternoon.
The LAV MOS guidance MVFR CIGs may be a little too pessimistic
during this period.
As mentioned in the public discussion, there are questions related
to TS coverage with the late afternoon/early evening cold frontal
passage. Best TS chances appear for TUP Saturday evening, after
the valid TAF period.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
533 PM CST Fri Mar 8 2019
.UPDATE...For 00Z Aviation discussion below
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 315 PM CST Fri Mar 8 2019
The previous forecast remains on track. The only change was to try
to tighten up the snowfall gradient on the southern edge of the
heavy snowfall area. As of now it appears that snowfall gradient
will extend from just west of Mankato through the Twin Cities. This
gradient will wash out north and east of the Twin Cities as
temperatures cool overnight and the snow becomes more widespread.
Given the uncertainty, decided to keep the Winter Storm Watch going
since there could be significant sleet accumulation, plus the precip
will fall with winds of 20 to 25 mph.
Tried to use the forecast soundings off the HRRR to get an idea of
where the warm nose would persist, and where it would wetbulb down
below freezing. Generally speaking areas west of the Lower Minnesota
River Valley will have mainly snow, but areas to the east will have
a wintry mix cut down on the overall snowfall totals. This ends up
putting the northwest part of the Twin Cities in the 8-10" snowfall
range, with the southeast part in the 4-6" range. A subtle change of
1 or 2 degrees will make all the difference, so could easily see
this forecast changing over the next 24 hours.
The upper level wave driving this system will take on a negative
tilt, so that should enhance the forcing and lead to some
impressive snowfall rates of 1 to perhaps 2 inches per hour. East
wind of 20 to 25 mph will lead to drifting snow, so with the full
snowbanks could see drifts of 2 or 3 feet very common across the
Winter Storm Warned area. In the wake of this storm winds will
continue in western and southern Minnesota, so the Winter Storm
Warning will continue through Sunday morning. Do not expect
blizzard conditions since the cold air advection is not overly
strong, and the surface low remains fairly steady with minimum
pressure around 988 mb. The precip will end across western MN on
Sunday, and winds will decrease.
.LONG TERM...(Sunday through Friday)
Issued at 330 PM CST Fri Mar 8 2019
Headlines will gradually end over the CWA during the day Sunday
as the snow ends and winds subside in the wake of the storm. Highs
pressure and quieter conditions will remain Monday and Monday
night with below normal temperatures.
The next strong storm system is forecast to rotate through the
southwest CONUS trough and lift into the Colorado/Oklahoma
panhandle region by Wednesday morning. Long term deterministic
models are more in line with the more western track the previous
12z GFS model run indicated yesterday. With this track, the
surface low will lift north/northeast toward central MN by
Thursday morning. Deeper moisture is expected to lift north ahead
of the storm, with integrated water vapor transport(IVT)
standardized anomalies of 3 to 4 standard deviations above normal
moving into southern MN Wednesday. Precipitable water values of 2
to 3 standard deviations above normal are forecast for the same
time period. This would bring at least 0.75 inch PW`s with the 12z
GFS indicating at least 1 inch. The heaviest precipitation is
expected to occur later Tuesday night through Wednesday evening as
the main low lifts across MN. QPF should range rather high with
the event, with 1 to 2 inches likely across much of the MN
portion of the CWA. We could see a rain/snow mix develop into
Tuesday night as the surface low approaches, with much of the
precipitation expected to fall as rain Wednesday. Some isolated thunder
will also be possible, especially over the southeast as the low
moves across Minnesota. The best LI`s trend slightly negative over
the southeast as a pocket of mid level lapse rates of around 7-7.5
C/km moves into south central MN Wednesday afternoon. This will
no doubt generate some localized flooding, especially in urban
areas where storm drains remain snow covered or frozen. Also,
small streams will likely see water rises over the ice. It will
overall begin to ripen the snow pack along with air temperatures
rising to the lower 40s across the easter CWA.
The system lifts through Thursday with precipitation ending
Thursday night. Temperatures are expected to trend back below
normal again for Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 534 PM CST Fri Mar 8 2019
The primary change in the TAFs was to introduce more of a wintry
mix at central/southern sites. KAXN and KSTC should see primarily
snow as the precipitation type, but KRWF/KMKT/KMSP/KRNH/KEAU will
most likely see a mix until late Saturday afternoon. That could
include a period of freezing drizzle at event onset for some, but
surface temperatures look to warm above freezing between 18Z and
20Z. By 00Z Sunday, snow should be falling area-wide, with the
heaviest at northern/western sites (KSTC/AXN/KRWF, and KMKT on the
eastern edge of the heavy snow axis). East/southeast winds will
become gusty on Saturday.
KMSP...
Main change was to include a longer duration of a wintry mix, with
the transition to all snow not expected to occur until 22Z Sat.
When the precip starts around the noon hour, surface temps should
be above freezing, so do not expect freezing rain/drizzle at this
time. Sleet will however be a possibility until the transition to
snow occurs around 22Z. LIFR conditions are possible during the
evening.
/OUTLOOK FOR KMSP/
Sun...MVFR/IFR with -SN early. Then, MVFR. Wind NW 15-20G25 kts.
Mon...VFR. Wind WNW 10 kts.
Tue...VFR. Wind SE 10-15 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Warning from noon CST Saturday to 7 AM CDT Sunday
for WIZ014-023>026.
Winter Storm Warning from 3 PM CST Saturday to 10 AM CDT Sunday
for WIZ015-016-027-028.
MN...Winter Storm Warning from 9 AM CST Saturday to 1 PM CDT Sunday
for MNZ041-042-048-049-057>059-066>069-076-077.
Winter Storm Warning from noon CST Saturday to 7 AM CDT Sunday
for MNZ043>045-050>053-060>063-070-078.
Winter Storm Warning from 6 AM CST Saturday to 1 PM CDT Sunday
for MNZ047-054>056-064-065-073>075-082-083.
Winter Storm Watch from Saturday morning through Sunday
afternoon for MNZ084-085-091>093.
&&
$$
SHORT TERM...JRB
LONG TERM...DWE
AVIATION...LS
Area Forecast Discussion
National Weather Service Marquette MI
636 PM EST Fri Mar 8 2019
.SHORT TERM...(This evening through Saturday)
Issued at 314 PM EST FRI MAR 8 2019
Earlier this morning an upper level trough passed over Southern
California and has since reached the Rockies. This is also evident
through the general upper-level troughing across the western
portions of the CONUS with slight ridging through the Central Plains
this afternoon. Light WAA and 290K-295K isentropic lift can be seen
on both the GFS and RAP this afternoon through tonight in west and
southern portions of Upper Michigan. This slight lift has led a
broad area of higher clouds for the UP and will have the additional
chance to produce a few flurries this evening. Accumulations, if
any, will be light as moisture is lacking through the DGZ with
saturation staying at 3kft or less.
Increasing clouds tonight will provide warmer lows tonight than the
last few nights. Clouds out east will be delayed and temperatures
have been lowered accordingly. For Saturday, clouds will continue to
build throughout the area as a broad area of WAA and isentropic lift
continue ahead of the surface low that will impact us Saturday night
into Sunday morning.
.LONG TERM...(Saturday night through Friday)
Issued at 319 PM EST FRI MAR 8 2019
Still looking at two systems for our area Saturday night into Sunday
then again Wednesday and Thursday. Weekend system will produce
moderate accumulations of wet/heavy snow along with gusty winds and
patchy blowing snow on Sunday. Second system looks warmer with
mainly rain expected.
Upper level trough over the southwest CONUS moves to the central
Plains by Saturday afternoon with sfc low deepening to around 990mb
near Kansas City. Negative tilted upper trough and associated 988 mb
sfc low is expected to lift into the Upper Great Lakes Saturday
night with sfc low staying around 988mb reaching northern Lk
Michigan by daybreak Sunday. Overall the general idea of this system
remains consistent; marginal QPF amounts for a warning snow event,
lower SLRs/wetter snow and gusty nw winds on Sunday as the system
exits the area. Trends are farther east with sfc low track, so other
than some drizzle/freezing drizzle late Saturday night over the
southeast/east forecast area, looks like ptype for all areas remains
snow. Majority of steadier/accumulating snow does not arrive until
late Saturday evening, even over the south and WI border zones. Will
keep the SPS going and let mid shift see if any areas will need a
warning. Otherwise, they can put advisory out for most if not all of
western and central Upper Michigan for the expected wet and heavy
snow.
Behind the system Sunday night and Monday, nw winds will result in
light lake effect downstream of any openings in the ice cover on Lk
Superior. Deep moisture and H85 temps are marginal leaving only
shallow moist layer with sub 5kft inversion height. High pressure
ridge Monday night through Tuesday night will keep weather dry.
Temps on Tuesday may reach well into the 30s, if not even over 40F
as long as mid clouds hold off til later in the day or at night.
Next system arrives late Tuesday night through Wednesday with
primary surge of precipitation lifting through on Thursday. Upper
level system gets deflected north as it grinds into strong upper
ridge over eastern North America. Sfc low tracks farther west than
this weekend system, so looks like a warmer system for sure with
rain the main ptype until colder air works back in later Thursday or
Thursday night. 12z GFS was a lot wetter with this system with over
an inch of qpf encroaching on western Upper Michigan. GEFS
probabilities hint at higher qpf over far west Upper Michigan as
well and on to the west over Lk Superior. Previous runs of the GFS
were more toned down though, as are the current forecasts of the
ECMWF and GEM-NH.
Temps should rise into the upper 30s or lower 40s on Wednesday, only
fall into the lower 30s on Wednesday night and push back into the
40s on Thursday before cooler air moves in from the west late
Thursday or Thursday night as upper low and sfc low head east as
bulk of jet energy surges ahead of the trough making it more
progressive. Even though it is a short duration warm up, could see
at least some limited responses from melting snow. Forecast dwpnts
reach lower 40s over the south but stay in the 30s elsewhere. The
higher dwpnts will help the melting process and could also result in
better chances of advection fog as the higher dwpnts flow across the
melting snowpack. Both of these issues will have to be addressed as
we get closer to this system. Please note that our office has
started issuing our routine spring hydrologic outlooks (ESFMQT)
with complete details on current and expected snowpack and weather
conditions, especially in regard to flooding potential.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 634 PM EST FRI MAR 8 2019
VFR conditions are expected through the TAF period at KCMX and
KSAW. Expect VFR conditions at IWD to slowly become MVFR late
tonight/Saturday morning as lower upstream ceilings move into the
area. It is possible that IWD will go between VFR and MVFR
through the period. &&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 314 PM EST FRI MAR 8 2019
Winds over Lake Superior will approach 30 knots on Saturday night
and and then expect low-end gales Sunday afternoon. Winds will
drop below 20 knots Monday night until Wednesday as winds will
approach 30 knots again. Expect gusts over Lake Superior in the 20
to 30 knot range through the rest of the forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JAW
LONG TERM...JLA
AVIATION...Voss
MARINE...JAW
Area Forecast Discussion
National Weather Service San Francisco Bay Area
411 PM PST Fri Mar 8 2019
.SYNOPSIS...Light shower activity across the Monterey Bay will
taper off through the afternoon and evening. A different storm
system will bring another shot of beneficial rain tomorrow with
lingering showers into tomorrow night. Dry high pressure returns
Monday with another chance of light rain by Tuesday as another
fast moving system passes through.
&&
.DISCUSSION...as of 01:45 PM PST Friday...A weak disturbance
passing through California has helped to excite a broad unstable
airmass in place across the state and the nearby coastal waters.
Visible satellite imagery depicts scattered cumulus clouds
developing in this unstable air mass while KMUX radar shows light
to moderate returns under the deeper convective cells. Radar
returns have generally been below the threshold that would signify
hail while convective cloudtops are at a relatively shallow
5000-10000 feet. That said, convective shower activity has been
slightly more robust and widespread than models suggested, with
isolated showers as far north as the Golden Gate into the early
afternoon. The bulk of the shower activity has been focused across
the Monterey Bay and Big Sur regions, where generally 0.05-0.20"
of rain has fallen since midnight. Showers will likely continue
across the Monterey Bay region through the afternoon before
finally tapering off later this evening.
Temperatures began the day 3 to 10 degrees cooler than the
previous morning given the cooler air mass and pockets of mostly
clear skies, but are now running in line with yesterdays mid 50s
readings. These temperatures are roughly 8 to 12 degrees below
normal readings for early March. Temperatures tonight are expected
to be slightly cooler than last night, particularly for the inland
portions of the region though overnight lows may be limited by
increased cloud covering from an approaching storm system set to
arrive Saturday morning.
Short term forecast models generally agree that a storm system
currently 600 miles west of Point Mendocino will begin to spread
another round of precipitation across the region prior to sunrise
Saturday morning. Lighter warm sector precipitation should give
way to occasionally moderate frontal precipitation shortly after
sunrise for the North Bay before shifting southward and inland
through the day. The local WRF and HRRR suggest that the frontal
precipitation will shift south of the Golden Gate by the late
morning before spreading deeper southward and inland by the early
afternoon. Lighter post frontal showers will then persist through
the remainder of the day before mostly tapering off overnight
Saturday into Sunday. A few weak isolated showers could persist
into Sunday, but most locations should remain dry given the
limited coverage and intensity. Storm total rain from this system
should be highest across the North Bay, particularly the coastal
range, where up to 1.50 to 2.00" are possible The North Bay
valleys could see around 0.75 - 1.00" while locations farther
southward and inland will see progressively less, such as around
0.50" near San Francisco and Oakland and 0.25-0.33" near San Jose
and Monterey. Southerly winds will become breezy to occasionally
gusty through Saturday morning but are expected to remain below
wind advisory criteria throughout the storm system.
A muted warming and drying trend is forecast to occur on Monday
under weak high pressure aloft. This is trend ends abruptly as a
different storm system is set to impact the area on Tuesday.
Models agree this system will be weaker than previous storm
systems and move at a quick clip. Light rain accumulations are
expected through the day Tuesday, but may be enough to be a
nuisance for any outdoor events and rush hour commutes.
Dry conditions return for the tail end of the week from Wednesday
through Friday though models hint at another weak wet system
impacting the area next weekend.
&&
.AVIATION...as of 4:00 PM PST Friday...Quiet afternoon with mainly
scattered cumulus clouds. VFR expected tonight. The next system
will spread lower cigs into the Bay Area after 12Z with a short
period of steady light rain Saturday afternoon. Northwest winds
this evening switching to the southeast late tonight. Southeast
winds gusting to 20 kt Saturday morning.
Vicinity of KSFO...VFR through tonight. Northwest winds gusting to
25 kt through 04Z. Increasing clouds with cigs 3500-4500 ft
Saturday morning. VCSH possible after 12Z with more widespread
coverage of light rain late Saturday morning through Saturday
afternoon. Southeast winds increasing to 15-20 kt late Saturday
morning.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR with scattered clouds tonight.
Increasing clouds after 12Z with light rain in the afternoon.
Northwest winds 5 to 10 knots becoming SE overnight.
&&
.MARINE...as of 03:39 PM PST Friday...While wind speeds have
diminished this afternoon, winds will being to increase late
tonight into Saturday morning in advance of an approaching storm
system. This system will result in gusty winds into Saturday
along with a chance of rain showers. Another system will arrive
on Tuesday with stronger northwest winds and rain showers.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm from 9 PM
SCA...SF Bay from 3 AM
SCA...Pt Arena to Pt Reyes 0-10 nm from 3 AM
SCA...Pt Reyes to Pigeon Pt 0-10 nm from 3 AM
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 3 AM
&&
$$
PUBLIC FORECAST: DRP
AVIATION: W Pi
MARINE: RGass
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Raleigh NC
937 PM EST Fri Mar 8 2019
.SYNOPSIS...
A stationary front will linger across South Carolina and Georgia
through Saturday night. A surge of warm and moist air aloft will
produce areas of light precipitation over North Carolina through
tonight. The stationary front to the south will lift north as a warm
front late Saturday and Sunday, before a cold front crosses the area
Sunday night. Dry weather will return under high pressure early next
week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 935 PM Friday...
Evening update: Intensity of the rainfall has decreased over the
past couple of hours as a wave moved south and east of the area.
Still expecting light rain or drizzle south of 64 but areas to the
north have seen an end to the rain at this point. SREF and HRRR
visibility fields are targeting the Triad for potential areas of fog
overnight. So far visibilities have dropped but only to MVFR levels.
CAMs also suggesting another weak wave moving through the southern
counties between 6 and 9z. Lowered low temperatures a bit across the
north as have already reached the upper 30s. Expect mid 30s across
the north to low 40s south. Previous discussion follows. -Ellis
Widespread light rain is currently crossing S and E portions of the
forecast area at a much faster pace than CAM runs from just a few
hours ago depicted. Only the RAP appears to be catching up to
reality, although it, too, is a couple of hours too slow.
Nevertheless, the precip has been mostly light, a trace to a couple
of hundredths of an inch, owing to the still-fairly-high cloud bases
and continued dry low levels. The leading subtle perturbation
helping to drive this current rainfall will exit to our east
shortly, creating a relative lull with only patchy light rain for an
hour or two. But additional rain now over TN associated with another
mid level perturbation is poised to overspread NC starting late this
afternoon, and high rain chances should continue well into tonight,
with the greatest coverage across southern NC where low level moist
upglide will be strongest and deepest, through the 285-295K layer,
near the low level frontal zone sitting across SC. Mid-upper levels
will dry a bit across NW and far N sections later tonight, so expect
a trend toward lighter and more patchy rain and areas of drizzle
there overnight, while higher pops for mostly rain persist across
the south. Thick overcast skies will dominate, with areas of fog
developing, particularly across far N and NW sections, within deeply
stable air. Lows are expected to range from the upper 30s N to mid
40s S. -GIH
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 340 PM Friday...
The stable pool will remain locked in over central NC through much
of Sat, albeit with rising cloud bases, with high pressure centered
over W Quebec nosing southward. The W-to-E frontal zone will hold
just to our S into the afternoon, but is expected to edge northward
into the SE CWA late in the day. 850 mb winds from the SW will
increase through the day, strongest over the W, as a potent
shortwave trough over the central CONUS lifts NE into the Great
Lakes Sat/Sat night. Moist upglide will persist, deepest over the SW
CWA, although the downstream ridge axis shifting over the Carolinas
and subsequent drying aloft (above minus 5C) will limit precip
amounts especially over NE sections to patchy rain/drizzle. The
shortwave trough itself will track well to our NW but the increasing
mid level flow over the NW CWA will re-moisten the mid levels there
late Sat into Sat night, and pops in the NW Piedmont will be trended
back up to good chances, with lower pops in the E and SE closer to
the offshore-drifting mid level ridge axis. Expect highs Sat to be
in the mid 40s NW ranging to upper 50s-near 60 in the SE. Will
maintain chance pops Sat night, higher NW and lower SE, with temps
rising as the warm front advances to the N and NW. The stable air
mass is likely to hold over the NW Piedmont, however, and temps
there should rise just into the upper 40s to near 50, while the
remainder of the forecast area gets well into the 50s. -GIH
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 255 PM Friday...
The main wx story for Sunday and Sunday night will be the passage of
a cold front, progged to move across our CWA during the late day,
into the evening hours. In advance of this front, several bands of
showers will move across our area, but we noted that QPF values have
been trending down with recent model runs, thanks in part to the
bulk of the upper energy lifting by well to our north. In any
event, look for QPF ranging from about 1/4 to 1/2 inch, highest east
of I-95.
The front and assoc moisture is then progged to move well to our
south by mid-day Monday, with a clearing sky trend to follow. With
a sfc and mid level ridge building over the region, look for fair
weather through at least mid-day Thursday, before the risk for rain
increases again late-week assoc with the next cold front approaching
and progged to move through on Friday. Given the slower movement of
that front and prolonged pre-frontal moisture advection, rain
amounts with that front should be heavier than the rain with
Sunday`s front.
Temps next week will run above normal most of the week, with Tuesday
night into Wednesday being the coolest period, thanks to northerly
low level flow associated with high pressure building in from the
north.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 730 PM Friday...
An area of light to moderate rain is currently moving across central
NC, producing sub-VFR conditions. The bulk of the rain will exit to
the east, though lingering rain and/or drizzle will persist into
Saturday, especially across the Piedmont. This will lead to lowering
cigs and visbys this evening and tonight as a CAD airmass becomes
locked in across the area. Cigs may briefly improve some across the
far eastern and southern TAF sites on Saturday, though likely to
remain below a thousand feet as the main surface cold front remains
to the south of the area.
Outlook: Sub-VFR conditions will continue through the remainder of
Sat night with patchy drizzle and light rain, most prevalent at
INT/GSO. Strengthening low level winds, atop the cold stable surface
airmass, from the SW Sat night may allows for a risk of LLWS at 2000
ft AGL as winds increase to 40-45 kts (at 2k ft). Warm weather is
expected Sun but with likely MVFR conditions and brief showers with
a passing cold front. An isolated storm is possible near FAY late
Sun. VFR conditions are likely to return for Mon/Tue/Wed as the
front settles to our S and high pressure builds in.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Blaes
NEAR TERM...Ellis/Hartfield
SHORT TERM...Hartfield
LONG TERM...np
AVIATION...BSD/Hartfield
Area Forecast Discussion
National Weather Service Tulsa OK
941 PM CST Fri Mar 8 2019
.DISCUSSION...
Forecast was updated to insert patchy dense fog mention and issue
a dense fog advisory for Carroll and Madison counties in AR thru 6
AM. Cool and moist conditions north of the warm front across
northern AR has allowed dense fog to develop. A check of
observations around the area does suggest it is patchy though. The
latest HRRR suggests that the best fog potential will stay over
north central AR and south central MO tonight.
Lacy
&&
.PREV DISCUSSION... /Issued 752 PM CST Fri Mar 8 2019/
UPDATE...
Some minor tweaks were made to the forecast tonight. See
discussion below.
DISCUSSION...
The forecast remains on track for the most part. The warm front,
which will play a role in the severe potential late tonight into
Saturday morning, is, in a sense, pivoting at this hour. The
western portion of the front, currently aligned from NE-SW into
northern TX, is beginning to lift north in response to the
deepening surface low over eastern CO. The eastern portion of the
front is remaining quasi-stationary over southern AR. By late
tonight, the warm front may gain a NW-SE orientation as the
western portion of the front is drawn north toward the surface
low. The theme of the forecast remains the same. Storms will
develop late tonight, likely elevated to start, across NE OK.
Other storms will get going over south central OK ahead of the
Pacific front closer to 12Z and will progress across southeast OK
and into western AR thru early Saturday morning. Storms along and
south of the warm front will pose a limited tornado threat, with
large hail to 2 inches in diameter the main threat. Damaging winds
are a threat as well, even north of the front where a shallow
stable layer near the surface will exist. The tornado
probabilities on the DSP (Decision Support Page) were tweaked to
show the expected orientation of the warm front tonight. Overnight
low temp forecast was adjusted as well with some sites already
below the forecast, though they should be near their mins now with
a steady or slow rise in temps after midnight.
Lacy
PREV DISCUSSION... /Issued 552 PM CST Fri Mar 8 2019/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
MVFR ceilings are expected to spread back over the CWA this
evening and overnight tonight ahead of an approaching dryline and
cold front. Thunderstorm are forecast to develop late tonight
across Eastern Oklahoma and move into Northwest Arkansas early
Saturday morning ahead of the dryline. IFR conditions and gusty
winds will be possible within the convection. Continued with tempo
groups for timing. Behind the convection...VFR conditions with
gusty southwest winds becoming gusty to strong westerly winds and
mostly clear conditions from west to east during the mid morning
to early afternoon hours Saturday.
PREV DISCUSSION... /Issued 256 PM CST Fri Mar 8 2019/
DISCUSSION...
Severe weather likely overnight with the potential for very large
hail, including at least a limited tornado threat along and south
of I-40. This afternoon, frontal boundary was located over far
southeast Oklahoma near a Wilburton, Poteau line. South of the
boundary, temperatures have warmed into the lower 70s.
Strong upper storm system currently located over southern NV will
shift east tonight, becoming negatively tilted as upper trough axis
lifts into the central Plains by Saturday morning. In response,
multiple clusters of strong to severe thunderstorms are expected
to develop by 09Z with storms rapidly spreading through all of
eastern Oklahoma by 12Z and across the remainder of northwest
Arkansas by 15Z. Elevated instability in excess of 2000 J/KG in a
few areas, coupled with strong deep layer shear around 60-70 knots
will support embedded supercells with the potential for very
large hail up to the size of tennis balls given the cold temperatures
aloft/steep lapse rates. In addition, warm front is forecast to
lift near or just south of I-40 by this time, which could provide
an enhanced severe threat with damaging winds and a few brief
tornadoes possible.
Thunderstorms will likely shift east of the region by mid morning
Saturday with the severe weather threat ending. Still expect
strong/gusty west winds to develop behind departing system with
gusts to 35-40 mph across far northeast Oklahoma. Although
widespread precipitation is expected, fine fuels will rapidly dry
out Saturday afternoon as temperatures warm into the upper 60s to
lower 70s with RH values in the 25-35 percent range.
Active weather pattern will continue into the early to middle part
of next week as another strong/highly amplified upper trough
moves out the desert southwest into the southern/central Plains.
Shower/thunderstorm chances will increase by Tuesday as stronger
isentropic lift develops north of frontal boundary ahead of main
storm system. Models in better agreement concerning timing of main
convective line Tuesday night into Wednesday morning with heavy
rainfall possible. Although surface based instability is expected
to be marginal, very strong low level wind fields suggest at least
a limited severe threat in addition to the heavy rainfall potential.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 50 71 35 54 / 90 50 0 0
FSM 54 74 41 60 / 90 80 0 0
MLC 54 74 40 53 / 90 50 0 10
BVO 48 67 30 53 / 90 50 0 0
FYV 49 68 34 53 / 90 90 0 0
BYV 42 68 36 54 / 90 90 0 0
MKO 51 69 38 53 / 90 60 0 10
MIO 47 67 34 52 / 90 80 0 0
F10 49 71 38 52 / 90 50 0 10
HHW 63 74 42 58 / 80 60 10 20
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...Dense Fog Advisory until 6 AM CST Saturday for ARZ002-011.
&&
$$
LONG TERM....30