Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/01/19
Area Forecast Discussion
National Weather Service Bismarck ND
852 PM CST Thu Jan 31 2019
.UPDATE...
Issued at 852 PM CST Thu Jan 31 2019
The 01Z RAP has caught on to a trend of lowering cloud heights
across south central North Dakota, and now paints a large swath of
dense fog developing overnight east of the Missouri River and
generally between Highway 200 and the South Dakota border. Added a
patchy fog mention to the forecast to account for this. While
confidence in the low clouds is high because it is already being
observed, other parameters (such as high clouds and stronger
winds just above the surface) do not favor fog development. Will
continue to monitor closely.
UPDATE Issued at 549 PM CST Thu Jan 31 2019
Made some minor adjustments to overnight temperatures. Lows are
expected to occur by around 9 PM CST, with slowly rising
temperatures thereafter. Otherwise, blended in current
observations and trends for this update.
&&
.SHORT TERM...(This evening through Friday)
Issued at 205 PM CST Thu Jan 31 2019
Low temperatures will be a challenging forecast tonight,
particularly as the low-level air mass continues to modify on
warm air advection, but the 12 UTC guidance numbers are
relatively closely clustered with lows ranging from around just
below zero at Jamestown to the lower 20s in western ND.
A surface warm front is expected to move through all of western
and central North Dakota by Friday morning, yielding favorable
southwesterly boundary layer flow and a significantly-warmer air
mass. While uncertainty remains in the impact of the pre-existing
snowpack on surface warming, there has been strong run-to-run and
model-to-model consistency in this warmup and so we are
relatively confident in temperatures hitting the 30s for all of
western and most of central North Dakota. Low to mid 40s are
likely across the southwest.
.LONG TERM...(Friday night through Thursday)
Issued at 205 PM CST Thu Jan 31 2019
Long term forecast highlights include accumulating snow and
blowing snow Sunday and Monday, and the return of dangerous wind
chills next week.
Guidance suggests that a shallow cool frontal zone may drop
southward through northwest and central ND on Saturday, and
boundary layer winds are forecast to become more east-
southeasterly, which is less favorable for warming given the broad
upslope nature of their trajectory. Moreover, this scenario may
yield significant stratus development, especially near and to the
cool side of the shallow frontal zone, wherever it winds up. As a
result, forecast highs Saturday are cooler in most locales.
Thereafter, the 12 UTC GFS, ECMWF, and Canadian models and their
ensembles continued calling for southwest flow aloft developing by
Sunday as a mean 500 mb trough develops in the western U.S., and
they also continue to agree that a strong shortwave trough will
eject across the northern Plains Sunday into Monday. There remains
a broad consensus in the potential for accumulating snow and
blowing snow in this timeframe, although GEFS plumes show a large
spread in potential QPF outcomes, which is not surprising given
that even the deterministic 12 UTC GFS and ECMWF show two subtly
different outcomes to this event, with the ECMWF now stronger but
still further north than the GFS. Regardless, flow aloft is
expected to be progressive, which means that this shortwave may
exit quickly, but could also allow for another to be quick on its
heels with another chance of snow by Tuesday. In addition,
guidance continues to advertise a return of Arctic air,
particularly behind the second trough passage when 850 mb
temperatures may reach -30 C over western and central ND by
Wednesday, likely heralding renewed wind chill hazards.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 852 PM CST Thu Jan 31 2019
A tricky cloud forecast has materialized at KBIS. Lowering
ceilings had been observed over the past several hours, and latest
guidance suggested this trend would continue. However, the low
clouds have now shifted just to the east of KBIS. The expectation
at this time is that KBIS will remain on the western edge of the
IFR cloud deck until around 09Z. Will continue to monitor closely.
Confidence in lowering ceilings is much higher at KJMS, which is
firmly situated in the middle of the stratus deck. Could also see
MVFR visibilities from BR develop there, with conditions improving
around 15Z.
PREVIOUS DISCUSSION...MVFR ceilings remain possible across
central and eastern ND early this evening. These should gradually
transition to VFR from west to east later this evening. VFR
conditions are otherwise expected through this forecast period,
with light southerly winds.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Hollan
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...Hollan
Area Forecast Discussion
National Weather Service Caribou ME
914 PM EST Thu Jan 31 2019
.SYNOPSIS...
High pressure will build south of the area Tonight into Friday.
A low over Quebec with an associated trough will move through
the area Friday night and Saturday bringing a chance for snow.
&&
.NEAR TERM /THROUGH FRIDAY/...
9:14 pm: A cold night across the FA with temperatures mostly in
the single digits below zero north and single digits above zero
Down East. Along the coast there are still some spots in the low
to mid teens. The lowest wind chills are across the far north
with a wind chill of -23F at Frenchville and -20F at Caribou as
of 9 pm. Updated with the latest observations and made a few
minor tweaks, but overall the ongoing forecast is fine with no
significant changes at this time.
Previous discussion:
Main item this term will be the winds and continued cold temps.
Snow showers and blowing snow across the north and west this
afternoon will wind down later this afternoon into the early
evening. Sfc trof is forecast to swing across the region by the
evening. Partial clearing is expected tonight w/the winds
staying up overnight. This will lead to some very cold wind
chills into Friday morning with this very cold airmass in place.
Winds will drop off some overnight, but confidence is high that
speeds till hold up around 10 mph even outside the higher
terrain. The 16Z RAP and 12Z NAM match up well w/this setup.
Per collaboration w/GYX, put up a Wind Chill Advisory for the
northern 1/2 of the CWA including the Greenville region into
Friday morning.
Remaining very cold for Friday as the regime remains under a
cyclonic flow aloft. This will allow another sfc trof to slide
across the region Friday. WSW winds will kick up to 10-15 mph
sustained w/gusts near 25 mph. This in turn will lead to some
blowing snow especially across the north and western zones, but
less coverage. Once again, daytime temps will be well below
normal for the 1st day of February. CONSRAW guidance looked to
be in line w/the current situation and since this cold airmass
holds, decided to blend in its temps for daytime highs for
Friday. This yielded single numbers across the north and west
w/low to mid teens central and downeast. Winds will drop off
some later Friday night as the gradient relaxes, but speeds are
forecast to still be above 6 mph. This will allow for the blyr
to mix out keep a lid on any strong inversion. A disturbance is
shown by the ECMWF and GFS to move toward the region later
Friday night w/clouds gradually increasing. Most of this
cloudiness will be above 12k ft.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
A low pressure system in SW Quebec will bring snow to Maine
early in the period. The low pressure will move into the Gulf of
Maine as a Canadian high pressure ridge builds south across
Maine. The ridge will crest over the area Sunday morning then
build east of the area by the end of the period. A deep low in
the southern NE with a trough extending east into SW Quebec will
affect the area early in the long term period.
Loaded a blend of the GFS/NAM/ECMWF/GEM to smooth out the minor
differences in the models. Used NWPSCG1CAR for seas in the
coastal waters. Used Wind gust by factor through 12z added 15
kts to wnds for gusts, used GYX Wnd Gust tool for Gust for the
remainder of short term. Used GFS for QPF.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
The extended period will consist of rapidly moving systems. Lows
with associated frontal system rapidly moving through, brief
high pressure ridges separating the system. Generally mild day
time temperatures with cold nights through the period.
A low pressure system over Nebraska with trough extending east
into SE Quebec will begin to affect Maine early in the period.
The low will move NE into northern Iowa the warm front will
move into central Maine Monday morning. The low will continue to
track NE to the central Great lakes. The warm front will remain
across central Maine. Tuesday morning the low will continue
moving NE into central Quebec, the warm front will lift NE into
Northern New Brunswick, the cold front will move into western
Maine. Tuesday evening the low will track northeast into The
Gulf of St Lawrence. A Canadian high will build into western
Maine Tuesday evening and build trough the area by Wednesday
evening as the next system moves into western Maine. Early
Thursday morning the next frontal system will move into western
Maine and will move east of the area Thursday evening. Higher
pressure will build in through the end of the period.
Loaded a blend to smooth out the differences in the models,
however the solution leans more towards the ECMWF solution. Used
NAWAVE4 for seas in the coastal waters. Used windgust by factor
tool.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: VFR the remainder of tonight into Friday.
SHORT TERM: An area of lower pressure will move through the area
early in the period. MVFR lowered IFR in snow across the area
during the day Saturday, improving conditions Saturday
afternoon, to MVFR with snow coming to and end early evening.
Skies will clear conditions improve to VFR. A high pressure
ridge will build through the area Saturday night through Sunday
afternoon. Increasing clouds and decreasing ceilings Sunday
afternoon. A trough of lower pressure will extend into Maine
Sunday night. MVFR with conditions fall to IFR in snow Sunday
night through the end of period as a from Nebraska move
northeast into southern Ontario. Its associated warm front will
extend through central Maine.
&&
.MARINE...
NEAR TERM: A gale warning remain in effect overnight. A trof is
expected to swing across the region on Friday which will allow
for the winds to kick up again. There is a chance that the Gale
Warning may need to be extended for a few more hrs Friday
morning. Winds look as though they will drop off by the
afternoon and continue that trend into Friday night. Seas will
start to subside on Friday due to the continued offshore flow.
SHORT TERM: A Small Craft Advisory maybe required Saturday
morning for winds and seas otherwise winds and seas will below
SCA criteria.
&&
.CLIMATE...
Not looking likely that there will be any add`l snow at Caribou
through midnight and that our monthly total will be 59.8",
which is just one tenth of an inch shy of the all-time monthly
record that was established in December 1972.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Wind Chill Advisory from 2 AM to 9 AM EST Friday for
MEZ001>006-010.
MARINE...Freezing Spray Advisory until 7 AM EST Friday for ANZ050>052.
Gale Warning until 5 AM EST Friday for ANZ050>052.
&&
$$
Near Term...CB/Hewitt
Short Term...Norton
Long Term...Norton
Aviation...CB/Hewitt/Norton
Marine...CB/Hewitt/Norton
Climate...CB
Area Forecast Discussion
National Weather Service Houston/Galveston TX
817 PM CST Thu Jan 31 2019
.DISCUSSION...
The bulk of the rainfall activity is now occuring over the Gulf
waters expanding northwards but remaining over portions of the
coastal regions. For the most part, the activity has been light to
moderate inland with a few stronger showers producing moderate to
heavy rain over the waters. As a weak shortwave moves across the
forecast area overnight, expect the heavy activity to persist over
the Gulf waters through around 05-06Z with some lingering light
showers likely to move across the southern portions of the CWA
from time to time. Forecast soundings and model guidance continue
to indicate patchy fog development overnight through early
morning hours Friday. Rain chances will decrease as upper level
ridging moves across the region Friday. Temperatures were
slightly adjusted to better represent the current obs, but
overall, no significant changes were made to the previous forecast
package.
&&
.PREV DISCUSSION... /ISSUED 550 PM CST Thu Jan 31 2019/
AVIATION...
Very messy aviation conditions expected for the next 24 hours. A
weak short wave will bring light/moderate rain to area TAF sites
through 03-04z with the rain tapering off after 04z. A mix of
IFR/LIFR ceilings is expected through Friday morning with ceilings
possibly mixing out to MVFR by Friday afternoon. Moisture trapped
beneath an inversion will keep a mix of IFR/MVFR ceilings on
Friday night. 43
PREV DISCUSSION... /ISSUED 342 PM CST Thu Jan 31 2019/
DISCUSSION...
3PM temperatures are in the upper 50s to low 60s area wide, with
dewpoints in the mid 50s. Radar imagery shows most of the showers
and isolated thunderstorms concentrated along and south of I-10
and over the Gulf waters this afternoon. Short term guidance such
as the HRRR and TT WRF show precipitation inland winding down a
few hours after sunset around 9 PM this evening, but remaining
over the Gulf waters. The shortwave embedded in the upper-level
flow and coastal trough which is currently located in the
northwestern corner of the Gulf of Mexico will both slide eastward
overnight tonight and out of the region.
With a warm air advection pattern in place, low temperatures tonight
will again be warmer than last night, bottoming out in the 50s
region wide. Forecast soundings as well as SREF guidance are both
indicating the possibility of some patchy fog developing west of
I-45 before spreading eastward, beginning overnight and continuing
into the early morning hours Friday. Upper-level ridging will
fill in behind the shortwave, but should be fairly short lived, as
our next disturbance translates across the TX Panhandle and
through SE TX by early Saturday morning.
Still holding on to precip chances through the remainder of the
week and into the next, as multiple disturbances shift over the
region. On Saturday the atmospheric column will quickly moisten,
with a fairly saturated profile in place from 700 mb to the
surface by the afternoon hours. PW values will approach 1.0-1.2
inches area wide. Saturday should provide our next best shot of
showers and isolated thunderstorms. A muggy warm pattern remains
in place Sunday with yet another chance for showers. A weak front
Monday will stall out just north of the forecast area, keeping SE
TX under a bubble of warm moist air and onshore flow. Winds may
turn slightly more out of the west in our northern reaches around
College Station as a result of this weak front Monday, but quickly
turn back out of the south by Tuesday.
The next cold front isn`t expected to push through the region
until mid to late next week. Global guidance still diverge on both
the timing and amount of precipitation associated with this
boundary. One thing that the various global guidance did have in
common was the increase in moisture and precipitation both along
and behind the frontal passage in the 12Z runs. GFS remains the
fastest solution, with the wind shift hitting the coast by early
Thursday morning, while both the Canadian and ECMWF remain about 6
to 18 hours slower, with the ECMWF being faster than the Canadian
in the most recent run. Remaining consistent with the current
forecast given the variability amongst the models, and trended
towards the slower solutions, placing the front off the coast
closer to Thursday afternoon. Thursday should be the start of
cooler temperatures and drier dewpoints.
Hathaway
MARINE...
Prolonged fetch of moderate east winds has caused seas to increase.
Look for an additional bump in the seas tonight as the pressure
gradient slightly tightens and winds increase. Will go ahead and go
with an advisory for the Gulf waters tonight. Prevailing areas of
rain with some embedded storms should move off to the east late
tonight. Winds will decrease and slowly veer more toward the se this
weekend.
A favorable setup for sea fog development (warm airmass over cold
shelf waters) will be in place this weekend into next week. This
could end up being a somewhat prolonged fog event as the next front
isn`t forecast to push off the coast until early Thursday. 47
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 52 65 55 67 57 / 20 20 20 40 10
Houston (IAH) 51 66 56 68 57 / 40 20 20 40 30
Galveston (GLS) 55 62 57 63 58 / 80 20 20 40 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Small Craft Advisory until 6 AM CST Friday for the following
zones: Coastal waters from Freeport to Matagorda Ship
Channel TX out 20 NM...Coastal waters from High Island to
Freeport TX out 20 NM...Waters from Freeport to Matagorda
Ship Channel TX from 20 to 60 NM...Waters from High Island
to Freeport TX from 20 to 60 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION until 1 AM CST Friday for
the following zones: Matagorda Bay.
&&
$$
Discussion...24
Aviation/Marine...43
Area Forecast Discussion
National Weather Service Lincoln IL
914 PM CST Thu Jan 31 2019
.UPDATE...
Issued at 914 PM CST Thu Jan 31 2019
Snow is still occurring across northern parts of the CWA with most
of the snow occurring north of I-74. The snow has been light for
the most part and accumulations have only been around an inch from
the few reports that we have received. Expecting the snow to
continue this evening but begin ending around and after midnight.
Additional accumulation will also be limited with no more than one
half to one inch possible. Will be making some adjustments to
some of the forecast, but nothing major as everything looks on
track. Will keep advisory going in the north til after midnight,
but may end up ending it sooner than 3 am, given the lack of snow.
Advisory in the southeast will continue as forecast as precip is
still expected to advect into the area into the overnight hours.
Update will be out shortly.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 323 PM CST Thu Jan 31 2019
Short-wave trough diving southeastward through Minnesota/Iowa is
producing a swath of snow from eastern Iowa into north-central
Illinois this afternoon. 21z/3pm KILX radar imagery shows snow
falling along/north of a Galesburg to Bloomington line. HRRR has
been consistently suggesting the snow will develop slightly further
southward over the next few hours...with the heaviest/steadiest
snow concentrated along and north of the I-74 corridor. Due to the
very cold airmass still in place, snow-to-liquid ratios will average
around 25:1 across the northern CWA. As a result, am expecting
snow accumulations of 2-3 inches from I-74 northward...with around
4 inches along a Lacon...to Lexington...to Hoopeston line. There
will be a sharp gradient on the south edge of the snow area, so
amounts will quickly decrease further southwest...with no snow
expected along/south of a Rushville...to Taylorville...to Robinson
line. The snow will come to an end from northwest to southeast by
mid to late evening.
Light precip will develop on the back side of the departing wave
across the SE CWA overnight:however, with forecast soundings
indicating a lack of ice crystals, think any precip that occurs
will be in the form of freezing rain. Ice accumulations will be
less than one tenth of an inch, but will still be significant
enough to create a thin glaze of ice on the very cold roadways. As
a result, will be issuing a Winter Weather Advisory south of I-70
for late tonight into early Friday morning.
Once the early morning freezing rain comes to an end across the
SE, mostly cloudy and milder condtions are anticipated for the
remainder of the day. High temperatures will climb above freezing
everywhere south of I-72...with readings approaching the 40-degree
mark around Flora and Lawrenceville.
.LONG TERM...(Friday night through Thursday)
ISSUED AT 323 PM CST Thu Jan 31 2019
Significant pattern change will lead to a major warm-up this
weekend into early next week. The warming trend will be tempered
by the existing snow cover across central Illinois, as much of the
energy will initially go into melting the snow. Have therefore
lowered high temperatures across the northern half of the CWA on
Saturday...opting to keep locations along/north of a Macomb to
Bloomington line in the 30s...while areas further south where
little to no snow cover exists rise well into the 40s and even
lower 50s. Lowered highs along/north of I-74 into the middle to
upper 40s on Sunday due to residual snow cover, with all other
locations surging into the middle to upper 50s. By Monday, think
little or no snow will remain...so am expecting highs to range
from the lower 50s far NW around Galesburg to the upper 50s and
lower 60s further southeast across the rest of the area. Due to
the much warmer airmass flowing northward over the cold snow pack,
fog/drizzle will be a good bet across the northern half of the
CWA Saturday and Sunday.
Low pressure will develop in the lee of the Rockies across
northeast Colorado on Sunday...then will track into the northern
Great Lakes by Monday evening. With this particular track, central
Illinois will remain in the warm sector...with rain developing
late Sunday night into Monday. Once the low passes to the
northeast, it will drag a cold front through the area by Monday
evening...bringing an end to the rain and introducing slightly
cooler conditions. After a brief respite from the active weather
Monday night into Tuesday morning, another low ejecting out of the
Rockies will bring rain or a rain/snow mix Tuesday afternoon into
Wednesday. After that, a return to typical wintertime cold is
anticipated for the end of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 547 PM CST Thu Jan 31 2019
Forecast for SPI will be VFR through the period with clouds
through the night and then scattering out during the morning
hours. DEC will be VFR as well, but could see some flurries this
evening, ending around midnight or sooner. Like SPI, clouds will
scatter out during the morning. The other sites, PIA, BMI, and CMI
will see light snow this evening. PIA is currently at MVFR with
3sm vis and light snow. IFR conditions area still possible for a
couple of hours as snow should continue and could get worse off
and on. This applies to BMI and CMI, just the TEMPO IFR conditions
will last longer. Then before midnight at PIA to around midnight
at CMI, snow should have pushed east of the sites and VFR
conditions will prevail remainder of the TAF period. Clouds will
scatter out at these sites as well during the late morning. Winds
will be easterly through the night and then become variable during
the morning hours into the afternoon. Wind speeds of 10-12kts
likely tonight, but decrease overnight.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 3 AM CST Friday for ILZ027>031-037-
038-043>046.
Winter Weather Advisory until 9 AM CST Friday for ILZ066>068-
071>073.
&&
$$
UPDATE...Auten
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Auten
Area Forecast Discussion
National Weather Service Louisville KY
901 PM EST Thu Jan 31 2019
.Forecast Update...
Issued at 900 PM EST Thu Jan 31 2019
Currently have a nice band of snow falling over central IN, being
forced by the left exit region of an upper jet. This jet will push
east overnight, taking the better forcing with it. Our weather will
be more from gently upslope in the form of a warm front in the
region. Current KY Mesonet temperature readings show a gradient of
teens in northern KY to low 30s along our border with TN. Though
winds currently are from the east at most locations, we should see a
little more of a wind shift as the night continues and a warm
frontal boundary sets up. Isentropic lift along this boundary should
force new precipitation to develop a little after midnight west of I-
65 and continue forming eastward with that slab lift forcing precip
along and east of I-65 in the 9Z time frame.
Precip type is the next question mark. Time-height sections across
the region do show deep enough layer lift/moisture for us to see ice
crystals with the onset of precip, thus the snow forecast. As we get
into the mid morning hours we lose that moisture aloft, allowing for
a transition to more supercooled liquid droplets. With cold pavement
temperatures, still think we will see a switch to freezing rain and
then rain by late morning as we "warm" up. The end of the period
will switch more to drizzly conditions as we continue to lose
moisture aloft. Have updated the forecast with the latest high-res
forecasts, and the changes are not that significant. The areal
coverage of the advisory headline and the ongoing forecast still
looks good...so not planning a zone update at this time.
&&
.Short Term...(This evening through Friday)
Issued at 315 PM EST Thu Jan 31 2019
...Winter Weather Advisory for south-central Indiana and much of
central KY late tonight and Friday morning...
The weather is quiet this afternoon as mid and high clouds continue
to stream across the forecast area. Temps continue to slowly
moderate through the teens across northern counties and the 20s over
south-central KY.
The main concern occurs late tonight and Fri morning as a weak
shortwave digs SE within NW flow aloft. Models show decent low-level
warm advection/isentropic lift tonight. This will create gradual air
mass saturation as weak upward moisture transport continues. The
question is how soon and deep saturation will occur vs. boundary
layer warming late tonight across central KY. It appears temps will
bottom out this evening, then slowly rise overnight. Interestingly,
the HRRR has been showing a weak surface boundary developing W-E
over central KY in its raw surface temps with warming to its south,
and cooler, more steady or just slowly rising temps to its north.
The other caveat is temps aloft in the saturated layer. Model
soundings show saturation up to around -10 C which is just starting
to tough the dendritic snow growth zone (DGZ). However, ice
nucleation can initiate at temps a little warmer than -10 C, so am
still expecting precip to start out as light snow across southern IN
and north-central/east-central KY. However, may lose ice crystal
formation aloft by daybreak Fri and/or there could be a slightly
above freezing warm layer develop aloft. This would mean precip
changing to light freezing rain or perhaps a little sleet. While
total precip amounts will be light, any freezing precip will cause
impacts, especially for the morning rush. Snow amounts should be
under an inch in most places.
Over south-central KY, high res models show surface temps warming
overnight to above freezing. While this could occur, ambient road
and elevated surface temps will still be below freezing for awhile,
i.e., lag the air temp warmup. Thus, there could be a period of some
light freezing rain or drizzle over central KY/parts of south-
central KY, perhaps starting off as a very brief period of snow.
Over far south-central KY, think the warmup will be fast enough and
any precip start late enough to preclude much impact.
Based on all info, a Winter Weather Advisory is being issued for all
of south-central IN and much of central KY from 08-16 UTC, i.e., 3
am EST/2 am CST til 11 am EST/10 am CST. The southern edge of the
Advisory runs from Butler to Hart to Casey County. It is possible
that southern parts of the Advisory may be canceled before the
expiration time.
For the rest of Friday, surface temps will warm above freezing
areawide. While the precip will be moving out or dissipating with
time, low clouds will persist and there could be some liquid
drizzle. Expect high temps Fri afternoon in the upper 30s over the
Bluegrass to low-mid 40s in south-central KY.
.Long Term...(Friday night through Thursday)
Issued at 255 PM EST Thu Jan 31 2019
A nice warm-up is still expected starting this weekend as upper
level ridging moves in from the west, and the arctic high departs
off to the east. Highs on Saturday will get well into the 50s, and
60s look attainable by Sunday. Still thinking we`ll keep the weekend
dry, though some weak passing 500mb waves will bring some periods of
clouds and possibly some drizzle for parts of the weekend.
An active pattern will begin to take shape starting Monday. An area
of low pressure with an associated cold front will move into the
Midwest Monday morning. WAA ahead of the cold front will pull up
moisture and warmer air from the south. Should be enough
lift/forcing to generate some showers, and perhaps even some
isolated storms, Monday afternoon and evening. Models vary on how
far south the cold front will drop Monday night, but all are in good
agreement with it lifting as a warm front Tuesday and seeing the
warm air build back in quickly.
A strong cold front is then forecast to impact the region Wednesday.
Warm air and gulf moisture will stream in from the south ahead of
this front, and the combination of lift/forcing should result in
widespread showers. Model soundings show some weak instability with
strong shear, so will have to keep an eye on storm potential in the
coming days. Colder, drier conditions are anticipated behind the
front in the late week period.
&&
.Aviation...(00Z TAF Issuance)
Updated at 615 PM EST Thu Jan 31 2019
Wintry mix scenario setting up for Friday morning, as a warm front
slowly advances north across the region. Complicating the forecast
is the very cold ground temperatures, which should allow for a
period of freezing rain or snow in the SDF/LEX terminals and perhaps
HNB early Friday. That precip will transition over to light rain
before ending with a residual low-cloud deck the rest of the day
Friday. Winds will be somewhat variable as that front crosses, with
southerly winds taking over at least at LEX/BWG later in the period.
We could see a brief window of low-level wind shear at those sites
as well.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory from 3 AM EST /2 AM CST/ to 11 AM EST
/10 AM CST/ Friday for INZ076>079-083-084-089>092.
KY...Winter Weather Advisory from 3 AM EST /2 AM CST/ to 11 AM EST
/10 AM CST/ Friday for KYZ023>043-045>049-053>057-061>067.
&&
$$
Update...RJS
Short Term...TWF
Long Term....DM
Aviation...RJS
Area Forecast Discussion
National Weather Service San Diego CA
200 PM PST Thu Jan 31 2019
.SYNOPSIS...
A fast-moving low pressure system from the northwest will continue
to bring showers through early evening with scattered thunderstorms.
Friday will be dry but cool. A larger stronger storm will bring
widespread rain, with heavy rain on south-facing mountain slopes
late Friday night and Saturday. Strong winds are likely Saturday in
some areas Saturday. After the frontal passage late Saturday, some
snow will fall in the mountains. Low pressure continuing to the
north will bring occasional showers Sunday through Tuesday with fair
weather returning by Wednesday.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Showers and scattered thunderstorms continue moving through the
region this afternoon, with tapering from northwest to southeast
late this afternoon and this evening. Latest HRRR has most of the
precip ending by 8 PM except over eastern San Diego County and the
Riverside County mountains. Snow levels are quite high, generally
above 7000 feet, with only minor amounts of snow falling near
highest peaks.
Friday should have quite a bit of cloud cover but should be
precipitation-free being between systems. The Saturday system will
have an atmospheric river and that will combine with strong
orographics in the low-level saturated south-southwest flow to bring
heavy amounts of precip on the south/southwest facing mountain
slopes. A few light showers could start as early as late Friday
night, but the main orographic precip will occur Saturday, then the
frontal passage combined with favorable jet stream dynamics likely
will bring a period of heavy precip at lower elevations as well late
Saturday afternoon/early Saturday evening. Saturday rainfall will
likely be 1 inch or more in most areas except the deserts, but some
south slopes in SBD could get 5-8 inches. A flash flood watch will
be needed for the burn scars and may be needed for some non-burn
scar locations as well, including in Orange County and SW San
Bernardino County. Snow levels should be quite high Saturday,
probably at/above 8000 feet, then lower to 5000-6000 feet after
frontal passage, and moisture could remain deep enough (to over
10000 feet MSL) in the WSW flow for substantial mountain snows,
especially in San Bernardino County. There could be 6 or more inches
of snow Saturday night/Sunday in the SBD County mountains. Also,
strong south winds will be a problem in San Bernardino County as the
strong winds aloft will be brought to the surface due to a mountain
wave, mainly over the northern SBD county slopes and into the
adjacent deserts. Gust potential is around 80 MPH in places near
Lucerne Valley during the day Saturday, though winds will weaken
somewhat after the front passes through late in the day and shifts
the winds more westerly. Some coastal sites may have wind gusts over
40 MPH with the front late Saturday.
Onshore flow and continuous moisture to 800-700 MB should continue
showers Sunday wiht another strong upper low progged to move through
mainly northern/central California Monday into Tuesday. As we will
be on the south side of this storm with a weaker surface low, the
precip amounts will be considerably lower than Saturday. Fair
weather likely will return Wednesday, with a ridge developing off
the coast, though not a strong one.
&&
.AVIATION...
312100Z...Coast to Mountains: Areas of low clouds west of the mtns,
with bases 1500-2500 feet msl and tops to 9000 feet. Areas of inland
vis 2-5 miles. Showers and isolated TSTMS until 05Z. Cigs/vis
reduced in rain and fog, with higher terrain obscured. After 04Z
cigs will lift to around 3000 feet with SCT low clouds lingering
overnight. Confidence in cig impacts at TAF sites is low after 04Z.
Deserts: Variable clouds AOA 12000 feet. Lower clouds with bases
3000-5000 feet and showers between 22-05Z. TSTMS will be possible as
well this afternoon. Clearing after 05Z.
&&
.MARINE...
South winds today with isolated gusts over 20 knots. Showers and
isolated thunderstorms this afternoon. A frontal passage will
produce a sharp wind shift from southerly to westerly during the
afternoon. A more substantial storm system Friday night and Saturday
will bring stronger winds approaching gale force and larger swell.
Winds will decrease Sunday, but swell will peak then, possibly
creating hazardous seas.
&&
.BEACHES...
A winter storm will bring ISOLATED lightning strikes at the beaches
this afternoon.
&&
.SKYWARN...
Skywarn activation will be needed beginning at noon.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Watch from Saturday morning through Saturday afternoon
for Apple and Lucerne Valleys-San Bernardino County
Mountains.
Beach Hazards Statement until 7 PM PST this evening for Orange
County Coastal Areas-San Diego County Coastal Areas.
Flash Flood Watch until 6 PM PST this evening for Santa Ana
Mountains and Foothills.
PZ...NONE.
&&
$$
PUBLIC...Maxwell
AVIATION/MARINE/BEACHES...PG