Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/11/17
Area Forecast Discussion
National Weather Service La Crosse WI
547 PM CST Fri Feb 10 2017
.SHORT TERM...(Tonight through Saturday night)
Issued at 238 PM CST Fri Feb 10 2017
Main fcst concerns this period are precip chances mainly Sat
afternoon/evening, temperatures thru the period.
18z data analysis had a 994mb low near KINL, tracking east along the
MN/Ont border. Broad south and SW sfc-850mb flow across the region
south of this low at mid-day, spreading strong warming north/east
across MN/IA/WI. Cloud cover mainly a sct-bkn veil of cirrus,
allowing for plenty of sunshine to reach the ground across most of
MN/IA/WI. Where the ground was snow-free or nearly so across parts
of MN/IA, 18z temps were already warming into the low-mid 40s, with
low-mid 30s common over our mostly snow covered fcst area.
Model runs of 10.12 initialized well. Solutions, at least at 500mb,
remain similar for stronger shortwave to move across the nortern
Rockies tonight, into the northern plains Sat then into the Upper
Midwest Sat night. Trend by Sat night favors faster of the earlier
model runs, with the mid level trough axis to near the MS River
at 12z Sun. Some detail differences by Sat afternoon/night, but
overall the short-term fcst confidence is good this cycle.
For the short term, a dry, quiet, mild night tonight with the sfc-
700mb layer remaining on the dry side and actually dominated by WNW
cold advection flow. Moisture/cloud increase tonight above 700mb
with any forcing/lift remaining on the weak side in zonal flow
over the region. Forcing/lift increases across the area Sat with
approach of the mid level shortwave, with a weak/mdt band of mid
level FN convergence developing/moving somewhere across the
central/south parts of the fcst area Sat afternoon/evening.
925-850mb flow remains NW-N Sat with weak cold advection, with
model soundings/x-sections showing the 925-800mb layer struggling
to saturate with the weak/mdt lift above it. Area radars should be
lit up pretty good with returns by Sat afternoon/evening but
question is how much of this will actually reach the ground with
the drier air below 800mb. Some model consensus there will be a
brief period of moisture increase in the sfc-800mb layer sometime
Sat night with approach of the shortwave trough and PV
advection/dynamic cooling of the column. Expect there will be a
rather narrow band of precip reaching the ground late Sat
afternoon/evening were the strongest of the lifting mechanisms
overlap. This could be anywhere from along I-90 to a KOLZ-KDBQ
line. For now small chances of precip these areas Sat afternoon
then more 20-40% chances Sat evening into the overnight hours
reasonable.
Evaporative cooling into the dry sub-cloud layer would drop max
wet- bulb zero values into the -1.5C to +2.5C range by Sat
afternoon, with potential of a wintry mix of precip types. With
weaker lift and boundary layer temps looking be in the upper
30s/low 40s, bulk of precip chances Sat afternoon into early Sat
evening as -RA. With both dynamic and BL cooling Sat night, precip
would gradually change to -SN thru Sat evening into the
overnight, until mid level drying behind the 700mb trough axis
warms the cloud tops to above -10C. Perhaps a small -FZRA chance
toward Sun morning, but by then bulk of the lift is gone along
with precip chances. A blend of the guidance lows/highs for
tonight thru Sat night, with lows tonight/Sat night near/above the
normal highs, looks reasonable.
.LONG TERM...(Sunday through Friday)
Issued at 238 PM CST Fri Feb 10 2017
For Sunday thru Monday night: main fcst concerns this period are
mild temperatures.
Tight consensus among 10/12z models for the trough axis to move
quickly east of the area Sun, then shortwave ridging to build across
the region Sun night. This ahead of a stronger northern stream
shortwave to drop toward/across Lk Superior Mon/Mon night, with the
mid level flow strong NW by 12z Tue. Fcst confidence for Sun thru
Mon night is good this cycle.
With the sfc-mid level trough quickly exiting east Sun, any
lingering precip chances Sun morning over the NE end of the fcst are
very early in the day. Deep layered subsidence to spread across the
area Sun, but will have to watch for some lower moisture/clouds that
could get trapped under the subsidence inversion thru much of Sun.
With anti-cyclonic low level flow/high pressure building in,
consensus of decreasing clouds thru Sun is reasonable. After a bit
of a post low/trough cool down Sun, the next round of 925-850mb
warm advection quickly spreads across the area Sun night/Mon under
the shortwave ridging. 925mb temps back to near/above 0C by Mon
afternoon. If mixed that deep would support highs in the 40s. With
what is looking to be mostly sunny skies and SW winds of 10-20
mph for mixing, trended Mon highs 2 to 3 degrees above the
consensus. for now. With a deep, dry airmass over the area Mon,
and the lower level source region from the central/northern
plains, sfc-700mb trough axis with the shortwave dropping across
Lk Superior looks to do little more than bring a wind shift to the
NW Mon night. Other than warming highs a few degrees Mon,
consensus highs/lows for the rest of the Sun-Mon night period
look to be in the ballpark.
For Tuesday through Friday (days 4 to 7): main fcst concerns this
period are generally temperatures.
Medium range model runs of 10/00z/10.12z are in decent agreement on
a stronger norhtern stream shortwave dropping into the western great
lakes Tue, with a mid level low then migrating across the great
lakes into New England Wed/Thu. All this sets the area up under
stronger NNW mid level flow for Tue-Thu as some troughing lingers
over the great lakes and weak secondary shortwaves ripple down thru
the flow. Lesser model detail agreement by Fri, but consensus has
the pattern progressing as strong Pac energy moving onto the west
coast shoves rather strong ridging eastward into central NOAM.
Fcst confidence for Tue-Fri is average to good this cycle.
Tue-Fri continues to trend as a dry period with the NNW flow aloft
and the main shortwave energy passing north/east of the fcst area.
Lower level trough/front passes with the great lakes shortwave Tue.
Perhaps a small -SN chance NE of I-94 on Tue with its passage, but
looks mainly usher a cooler airmass/Can high pressure into the
region for Wed/Thu. The cooling only looks to send 850mb temps back
to near normal for Wed, with low level warm advection already
returning for Thu. This mainly dry W to SW flow from the central/
northern plains. With the mid level ridging being pushed into the
plains Fri, mdt/strong low level warm advection continue into Fri.
925-850mb temps progged to back to near/above 0C by Fri. Depending
on depth of diunral mixing, highs Fri could be well into the 40s
once again. For now, model/ensemble consensus of highs/lows for Tue
thru Fri looks good, remaining above normal for perhaps all but Wed
as the coldest core of low level air behind the Tue shortwave moves
across the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 547 PM CST Fri Feb 10 2017
VFR conditions expected through Saturday, although the ceilings
will be lowering through the day. An area of low pressure
currently over Colorado, will move east into central Illinois by
late Saturday afternoon as a weak short wave trough works across
the Upper Midwest. There should be good frontogenesis north of the
surface low and this forcing combined with the lift from the short
wave trough will work to saturate the column and cause ceilings to
lower. There is a lot of uncertainty whether this forcing will be
strong enough and remain over the area long enough to produce any
precipitation. Forecast soundings from the 10.18Z NAM and 10.21Z
RAP indicate a very dry sub cloud layer will be in place that
should cause most of the precipitation to evaporate and stay with
a dry forecast through the period.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...04
Area Forecast Discussion
National Weather Service Denver/Boulder CO
901 PM MST Fri Feb 10 2017
.UPDATE...
Issued at 900 PM MST Fri Feb 10 2017
Not many updates needed to the forecast for the next 24 hours.
Winds have weakened across the foothills and I-25 urban corridor
and should remain that way overnight. Winds will remain across the
Plains as well until the cold front impacts Colorado. Latest
high-res model guidance has the wind shift entering Colorado from
the north around 8 AM and reaching Denver metro around 10 AM, and
given this is not an arctic front the timing seems reasonable. By
noon the front should reach Limon and clear the BOU CWA early
afternoon. Behind the front winds will pick up significantly out
of the north and northeast at 15-25 mph and keep temperatures in
check...highs tomorrow in the mid 50s look on track most areas,
though Lincoln County could warm into the 60s before the front
arrives.
In the mountains strong WSW winds will continue overnight in the
25-35 mph range with a few gusts to 50 mph possible across the
highest mountain passes above 9500 feet. HRRR and ESRL HRRR have
precipitation beginning in the next few hours and latest
radar/satellite data show increasing echoes across western
Colorado moving east. Increased PoPs in the mountains to account
for the earlier arrival of precipitation. Temps are still warm
across the mountain valleys so it may start off as rain, but
expect it change over to snow quickly.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 331 PM MST Fri Feb 10 2017
Wind event across the forecast area has been slowly winding down
through the afternoon as temperatures climbed to record levels for
the month of February. Still seeing wind gusts of 45 to 60 MPH in
the foothills of Boulder County and gusts to 20 to 30 MPH on the
Plains and over the Palmer Divide. Fire danger levels remain
elevated due to the warm temperatures, low humidities and gusty
winds. Will let the Red Flag Warning remain in effect until the
early evening, when temperatures and winds come down.
In the mountains, moisture will be increasing from the west during
the evening hours with a mix of rain and snow expected to begin by
midnight. Mountain temperatures are warm this afternoon, but as
the moisture increases this evening and precipitation begins,
evaporative cooling of the column should be enough to keep any
mountain rainfall short-lived. Most mountain areas should be
receiving snow by sunrise. Models keep the precipitation from the
approaching system in the mountains, due to the strong westerly
component in the flow pattern. Thus only slight chance pops are
included on the plains. Snowfall amounts in the mountains could be
some 2 to 4 inches by sunrise and another 4 to 8 inches through
tomorrow afternoon. Will not issue any highlights at this time
since weather systems coming from the southwest tend to favor the
San Juan mountains, and reduce the amount of snow that falls in
Grand and Summit Counties. The other story tomorrow will be the
much cooler temperatures across the plains, as highs in the lower
to mid 50s will seem downright chilly after today`s record
breaking numbers.
.LONG TERM...(Saturday night through Friday)
Issued at 331 PM MST Fri Feb 10 2017
Models show a southwesterly jet maximum over the CWA Saturday
night. There is weak upper ridging in place Sunday with a closed
low over northern Baja Mexico by late afternoon. A weak upper
trough is progged to move across the CWA on Monday. Weak
northeasterly winds aloft are progged Monday night. There is
benign synoptic scale energy for the CWA on the QG Omega fields
Saturday night through Monday night. There is upslope in the lower
levels Saturday night. Southerly winds are progged Sunday and
Sunday night. There is more upslope progged Monday and much of
Monday night. For moisture, there is quite a bit progged for the
CWA in the mid and upper levels Saturday night, but not much in
the lower levels. There is better low level moisture on Sunday,
but its not as deep as Saturday night. Sunday night dries out
quite a bit, with a tad of moisture lingering in the high
mountains. There is some upper level moisture around here and
there Monday and Monday night. The QPF fields show a tad of
measurable precipitation over the southern CWA Saturday night and
over just the southwestern CWA Sunday in the day. There is a
little bit more over the southern high mountains on Monday. For
pops, will go with "likely"s for most areas of the CWA Saturday
evening. Pops will decrease overnight, with the best remaining
over the high mountains south of I-70 and Park County. By Sunday,
there will be minor pops relegated to the southwest corner of the
CWA. For temperatures, Sunday`s highs are 4-7 C colder than
Saturday`s. Monday`s highs are 2-5 C warmer than Sunday`s. For the
later days, Tuesday through Friday, models have upper ridging and
fairly weak northerly flow aloft all four days. There is little
moisture. Temperatures will be above seasonal normals.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 900 PM MST Fri Feb 10 2017
Winds across all three terminals have finally weakened this
evening. Expect westerly winds all three terminals, with DEN and
APA shifting to a drainage pattern after 08Z. BJC should stay
westerly overnight. On Saturday a cold front will impact the three
terminals. High res model guidance has it impacting DEN around
17Z, with APA and BJC less than an hour after that. Winds will
shift to the northeast behind the front. VFR conditions expected
with the frontal passage given the still sizable T/Td speads near
the surface. Rain chances increase at all three terminals after as
the cold air deepens and lift develops associated with the jet
streak, roughly after 23Z. MVFR conditions are possible after 23Z
as well with the precipitation and increased moisture in the low-
levels. At this point the precipitation should fall as rain until
06Z on Sunday. Any snow amounts look to be an inch or less at the
three terminals, with the best chance of accumulating snow at APA
and BJC with deeper low-level upslope flow.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Schlatter
SHORT TERM...Dankers
LONG TERM...RJK
AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Taunton MA
954 PM EST Fri Feb 10 2017
.SYNOPSIS...
A warm front approaches the region tonight and produces a
period of light snow with 1 to 3 inches of accumulation likely
by Saturday morning. Low pressure then brings a wintry mix of
precipitation and heavy snow to the area Sunday into late Sunday
night or Monday along with strong winds as low pressure
intensifies rapidly east of Cape Cod. Dry weather likely returns
Tuesday and then another chance of snow Wednesday and/or
Thursday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
10 pm update...
Radar confirms snowing aloft across southern New England but
very dry air near the surface (dew pts in the single digits) is
eroding the snow before reaching the ground. New 00z NAM has
snow overspreading the region between 10 pm and 1 am from west
east. Based on upstream observations this seems reasonable.
Steadiest snow appears to fall between 1 am and 4 am. 00z NAM as
well as latest runs from the HRRR and RAP continue to generate a
few tenths of qpf overnight with snow ending 7 am to 10 am
across the region. So overall not much change from previous
forecast with the expectation of an inch or two of snow for most
locations, isolated amounts up to 3 inches possible. By no means
a lot of snow but enough for snow covered roads and slippery
travel into Sat morning. Previous discussion below.
===============================================================
Previous Discussion...
No major changes with the forecast for tonight. Still appears
to be a good overrunning setup tonight as a warm front
approaches our region. No real question on precipitation type,
it will be a light snow. The most likely window for snowfall
should start between 10 pm and 1 am, and end later Saturday
morning. Most of the snow should fall tonight. Expecting a
general 1 to 3 inches of snow, with locally higher amounts up to
4 inches possible. It`s marginal, so no Winter Weather
Advisories have been issued.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Saturday...Precipitation gradually ends from west to east
Saturday morning. Most of the region should be dry by mid
morning. Developing south winds may be strong enough to push
temperatures above freezing, which means the precipitation may
end as a brief period of rain or a rain/snow mix towards the
south coast of New England, particularly across Nantucket.
Not a big storm by any stretch but snow covered roads will
result in slippery travel Saturday morning.
Near normal temperatures.
Saturday night...This is where the forecast starts getting
tricky. Surface temperatures should be sufficiently cold at the
surface to support snow across much of southern New England. One
issue will be how quickly we can moisten the dendritic snow
growth region, another will be low level temperatures above the
ground.
The lack of moisture in the snow growth region might lead to a
period of freezing rain or freezing drizzle early Sunday
morning. The thermal profiles may also contribute to that
potential. It`s also possible we could get a wintry mix across
southern New England, with rain toward the coast and a
snow/sleet mix farther inland.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Highlights...
* Intense coastal storm will lead to multi-hazard system occurring
Sunday into Monday
* High pressure on Tuesday into Wednesday
* Low confidence on another coastal system Thursday into Friday
Pattern Overview...
12z Guidance is in general agreement for the medium range but begin
to diverge for the long term. Building ridge across the northwest
CONUS will keep New England in a trough pattern for the remainder of
the period. Appears winter is here to stay. Attention first towards
weak ridging on Sunday morning as dynamic shortwave moves over
southern New England. This wave will develop and bomb out a surface
low just to the east of the area. This system will result in several
hazards for Sunday into Monday. Northwest flow aloft will continue
across New England before another dynamic shortwave moves over the
region. This is more uncertainty with this system, especially with
the low level features. The GFS appears more progressive and to late
to capture southern Plains surface low into a coastal storm, where
the EC is more amplified resulting in coastal low pressure late Wed
into Thursday. Ensembles are also indicating large spread so low
confidence beyond Wednesday night and beyond.
Sunday into Monday...
** Heavy snowfall possible north of the Mass Pike
** Strong wind gusts across eastern Mass
** Coastal Flooding issues are possible especially near the Cape and
Islands
Digging trough and closed upper level low will approach southern New
England on Sunday/Monday. Ahead of this system, WAA will lead to
overrunning Sunday morning resulting in wintry precip especially
across CT/western MA.
As the system advances, both 500 mb and 700 mb closed low
strengthens considerable, developing a surface low south of the
region on Sunday. As upper level jet dynamics moves into the region,
anticipate the surface low to bomb out east of southern New England
by Sunday night. This system has some incredible dynamics and
impressive low level baroclinic zone as well as a hint of rather
extreme deepening with a tropopause fold. Still some difference in
the placement of the low as the GFS is on the eastern side of the
envelope, but both of the deterministic and ensemble guidance is
pin-pointing this low to develop south of the region before
strengthening east of the area by Sunday night/Monday morning.
Biggest question with this system is the thermal profiles. Placement
of the low can change temperatures a few degrees which could result
in different p-types. Consensus is snow north of the Pike for the
event, with the potential for wintry mix across northern CT and into
NW RI. Rain along the I-95 corridor towards the Cape and the Islands
as the low moves eastward bringing in warmer air. As the low moves
east of southern New England and strengthens considerably, appears
that strong CAA will move-in collapsing the temperature profile and
changing the p-type to all snow by Sunday night/Monday morning.
Again the p-types can change in the coming days but this is general
consensus as of now. Went ahead an issued a winter storm watch with
surrounding WFOs. The watch is located where highest confidence of
6+ inches of snow could occur. There is the potential that the watch
may be expanded if the thermals are cooler than currently
advertised. Aside from the watch, winter weather advisories may be
needed for snow, sleet, freezing rain or the combinations of the
three. Still have a few more guidance cycles to determine this
outcome.
As the surface low undergoes bomb cyclogenesis, the pressure
gradient will tighten significantly. This will result in 925 mb LLJ
reaching between 40-50 kts. Steep Lapse rates and good mixing will
help bring these strong gusts down to the surface. Appears that
locations across eastern MA has the best shot to see wind gusts near
40-50 mph. This will result in wind headlines as well as blowing and
drifting snow on Monday.
Northerly to northeast winds on Monday will result in building seas
and storm surge. This surge combined with the seas and wind gusts
could result in minor to moderate coastal flooding across the
northern shoreline of the Cape, Cape Ann and Nantucket. Coastal
erosion is also possible.
Overall still some uncertainties with this system. However
confidence is increasing in heavy snow north of the Pike and gusty
winds across the east coastal MA. More details will be resolved in
the upcoming forecast so stay tuned.
Tuesday and Wednesday...
Weak ridging aloft will yield to a break in the precipitation on
Tuesday. Another weak wave will move through the area on Wednesday
which could out put some showers across southern New England. Low
confidence on Wednesday forecast as models are diverging on timing
and strength.
Wednesday night into Thursday...
Lots of uncertainty with this system as the EC brings another
impressive coastal storm to the region while the GFS is dry.
Ensembles guidance in both the GEFS and ECENS are still all over the
place as the potential outcomes to this system. Will need to watch
this timeframe over the next several days to get a better idea of
what could occur.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
03z update...
Not much change from previous TAFs. Snow arrives 03z-06z with
steadiest snow 06z-09z and then tapering off 12z-15z.
Accumulations mainly an inch or two with a few locations up to
3" possible. Snow will be accompanied by mainly MVFR conditions
with isolated brief IFR possible. Previous discussion below.
=================================================================
Tonight...
VFR at sunset but MVFR conditions in light snow arriving across
western sections of CT/MA toward midnight, and then eastward
into RI and eastern MA after midnight. Snow intensity may
approach moderate toward 12z Sat.
Saturday...
MVFR much of the day. Light to moderate snow in the morning,
ending as some light rain across CT/RI and southeast MA in the
afternoon. Storm total snow accumulation of 1-3 inches.
Saturday night...Moderate confidence. Areas of MVFR-IFR cigs and
vsbys may occur. Anticipate a few areas of -SN possibly mixed with
sleet south of a kBOS-kCEF-kBAF line. Patchy -FZDL or -FZRA
possible as well.
KBOS TAF...High forecast in trends. May see lingering snow
showers into the day Saturday.
KBDL TAF...High forecast confidence.
Outlook /Sunday through Wednesday/...
Sunday through Monday...Moderate Confidence. MVFR/IFR to start as
wintry mix moves into the region. Anticipate different p-types across
the terminals with snow to the north and rain to the south.
Conditions will deteriorate through the day and into the evening to
IFR/LIFR as any rain switches to snow. Anticipate gusty northerly
winds by Sunday night into Monday near 30-50 kts. BLSN is possible
on Monday.
Tuesday...VFR.
Wednesday...VFR with the potential for MVFr in any passing snow
shower.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
10 pm update...
Tranquil weather with ridge of high pressure moving across the
waters. Warm front approaches overnight and results in light
snow with vsbys 1-3 miles. Otherwise light winds and modest
seas. Previous discussion below.
====================================================================
Short Range /through Saturday/...High forecast confidence
through Saturday.
Tonight...
Winds diminish as high pressure moves across the waters.
However, snow overspreads the region, reducing vsby to 1 to 3
miles.
Saturday...
Weak low pres tracks directly over southern New England. This
results in light ESE winds becoming variable. Snow and rain in the
morning limit vsby but improve by afternoon on most waters.
Saturday Night...Winds expected to remain less than 25 kt.
However, increasing north winds and arriving swell may lead to
rough seas across some of the eastern coastal waters.
Outlook /Sunday through Wednesday/...
Confidence...Moderate.
***Intensifying storm system early Monday will result in high seas
and near storm force wind gusts***
***This could become a very dangerous scenario for mariners on
waters east or southeast of New England.***
Building seas across the region as surface low south of New England
begins to intensify and approaches the Gulf Of Maine. This type of
storm and how quickly is strengthens will result in the risk for
strong northerly winds near storm force, and waves in excess of 15-
20 feet for late Sunday night into Monday. Went ahead an issued a
storm force watch for immediate northerly ocean zones where
confidence is highest.
Tuesday...Winds should have diminished and seas should continue to
gradually subside.
Wednesday...Another coastal low system is possible on Wednesday.
This may result in build seas and winds across the waters.
&&
.TIDES/COASTAL FLOODING...
Risking is increase for the potential for coastal flooding
around the Monday midday high tide. 925 mb northerly jet
increases to near 40-50 kts. The potential for these gusts to
mix down as well as build seas could result in a surge that will
impact the along the north side of the Cape (Sandwich to
Dennis) and Nantucket Harbor. Still some uncertainty with this
system but appears that minor to moderate coastal flooding is
possible. However all of this will depend upon exact positioning
and timing of a potential explosive development of an intense
coastal storm.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Storm Watch from Sunday morning through Monday evening
for MAZ002>006-008>012-026.
RI...None.
MARINE...Storm Watch from late Sunday night through Monday evening for
ANZ250.
Small Craft Advisory until midnight EST tonight for ANZ250-254-
255.
Small Craft Advisory until 10 PM EST this evening for ANZ256.
&&
$$
SYNOPSIS...Belk/Dunten
NEAR TERM...Belk/Nocera/Dunten
SHORT TERM...Belk
LONG TERM...Dunten
AVIATION...Belk/Nocera/Dunten
MARINE...Belk/Nocera/Dunten
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service State College PA
1022 PM EST Fri Feb 10 2017
.SYNOPSIS...
A storm system will move through the region Saturday night and
Sunday. High pressure will return for early next week. After a
mild weekend, the cold front associated with this storm will
bring cooler conditions for Monday.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
Warm advection is helping support an area of light precip moving
out of eastern Ohio into western Pa. The HRRR has some
diminishing returns over the next few hours while the remainder
of the deterministic models show no QPF. I inserted the chance
for some flurries but no actual measurable precip for the
overnight.
The southerly flow will allow temperatures to stay steady or rise
as the night progresses.
&&
.SHORT TERM /MIDNIGHT THROUGH 6 PM SATURDAY/...
The snow will slip eastward and out of our hair this evening.
An upslope component to the southwest wind may lead to a few
flurries or sprinkles tonight, but clouds are the more-likely
result for the west. Temps should be rising by midnight, and
mins will likely be early in the night for most locations. Mid
20s to upper 30s will be around by Sat morning, and widespread
40s and lower 50s S are expected for the afternoon. However, a
marked increase in moisture will occur on Saturday evening with
dewpoints into the 30s and lower 40s by midnight. Rain should
develop over the west in the mid to late afternoon. This will
spread to the east and get everyone wet. Very high POPs are in
order for a 12 to 15 hour period.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Another highly energetic shortwave aloft will dive SE from the
upper great lakes to impact much of the NE U.S. for the second
half of this upcoming weekend.
Mid-level warm advection and increasing large-scale upper
diffluence late Saturday night and Sunday will lead to warm
advection precip as an area of high PWAT air (in excess of 1
inch) is transported NE from the Ohio River Valley and lifted
over a warm front (banked along the front range of the
Alleghenies. This front will have a tough time moving to the NE
across our CWA and scouring out the dense, shallow cold air
trapped across PA to the east of the Allegheny front.
Went a few to svrl deg F below the NBM`s fcst highs for Sunday
(Esp across the Susquehanna RIver Valley).
Model trends over the past 24 hours brought the Clipper/sfc low
track further to the south, and somewhere across the southern
half of PA or northern VA during the day Sunday.
The 12Z GFS is the weakest and furthest north with the low
track, while the 10/09Z SREF, NAM and EC are all quite similar
with the track of the main low just south of the Mason/Dixon
line, followed by rapid intensification off the NJ/Southern New
England Coasts Sunday Evening into early Monday.
Precip type will be a difficult call at several phases of the
storm (Clipper). Areas of -FZRA (and even a little sleet or wet
snow at the start near and north of RT 6) are likely across the
northern mtns of PA during the Day Sunday, before colder air
sweeps SE acrs the commonwealth and changes precip back to a few
periods of snow or snow showers with minor accums in most
places by Sunday evening. Periods of plain rain are expected
across the southern half of the state...with pockets of freezing
rain possible near the I-80 corridor.
The increasingly strong and gusty winds are another concern as
the sfc low rapidly deepens just off the New England Coast
Sunday night and Monday. Northwest wind gusts of 35-45 mph range
(with locally higher gusts possible) appear quite likely later
Sunday night into Monday. Still plenty of time to assess the
situation before pulling the trigger on a wind advisory.
Collaborated with surrounding WFOs and WPC WWD Graphics to
paint in some light ice accums Sunday. No FZRA or Winter Weather
Advisory planned yet, but will continue to mention it in the
HWO.
A narrow north/south wedge of miler air will follow the passage
of an inverted trough late Sunday afternoon, prior to the
arrival of the deeper colder air.
This will cause a quick/brief jump in temps back to near normal
highs across much of the region. However, the Scent Counties
and Laurel Highlands will surge into the 40s to l50s
respectively.
Snow showers and perhaps some brief squalls will accompany the
passage of the main upper vort max/mid level thermal trough
Sunday night with additional minor accums of a coating to 1/2
inch throughout the Ridge and Valley Region (and perhaps a few
inches across the snowbelt of NW PA and also the Laurel
Highlands.
Winds will gradually slacken Mon night into Tuesday as a ridge
of high pressure slides east from the Ohio Valley.
An area of low-mid level Warm Advection induced light snow may
brush the NW mtns Tuesday as another (initially weak) nrn stream
wave approaches from the Upper Glakes.
12Z EC continues its trend of being the most aggressive with
sfc low development to the South of PA during the midweek period
as it`s the outlier model with substantial phasing of nrn and
srn stream energy over the eastern U.S. and SERN Canada. Went
the mid ground between the aggressive EC and a host of other
model data (w/respect to POPS for snow). 12Z GEFS keeps the 2
separate stream waves detached with our region dominated by the
nrn stream for the second half of the week.
Another shot of cold air with gusty NW winds and mtns snow
showers will close out the week with low pressure deepening to
some degree near or off the New England Coast.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
A band of light snow associated with a warm front over the Great
Lakes has lifted north of the region this evening. Upstream
observations and model soundings support widespread VFR
conditions for the rest of the night. The only exception may be
developing low CIGs toward dawn at BFD/JST.
A strong SW flow aloft will create a period of LLWS over much of
the region overnight. Model soundings indicate the stronger
winds will begin mixing to ground level at JST by around 03Z,
ending the threat of LLWS there. Elsewhere, model soundings
indicate the inversion height and associated shear will occur
above 2kft at IPT, so no LLWS expected there overnight.
An increasingly moist westerly flow will develop Saturday,
likely resulting in IFR/low MVFR CIGs at BFD/JST, where the
moist flow rises over the Allegheny Plateau, and possible MVFR
CIGs east of the mountains.
Outlook...
Sun...Daytime rain/low CIGs likely. Evening shsn/reduced vsby
likely at BFD/JST and improvement further east.
Mon...Windy. AM shsn/reduced vsby possible BFD/JST.
Tue...No sig wx expected.
Wed...Snow showers/VIS reductions possible BFD/JST.
&&
.EQUIPMENT...
KFIG surface observation will be off line until further notice
due to failed power feed.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Dangelo/Gartner
LONG TERM...Lambert
AVIATION...Fitzgerald
EQUIPMENT...
Area Forecast Discussion
National Weather Service Lincoln IL
836 PM CST Fri Feb 10 2017
.UPDATE...
Issued at 836 PM CST Fri Feb 10 2017
A weak boundary approaching from the NW continues to help shift
the surface pressure gradient responsible for today`s windy
conditions off to the southeast. Meanwhile...low pressure
developing into far western KS will continue to approach overnight
interacting with the boundary over central IL by morning. As a
result...extensive high cloudiness over the area will eventually
be replaced by low cloud and drizzle working its way northward
Saturday morning. Fog may also develop overnight...especially
along the boundary where winds are weakest...however extensive
high cloudiness seems it may mitigate the radiational cooling
needed to form fog so latest guidance continues to be non-
aggressive on fog overnight. No significant updates planned at
this time to afternoon forecast package.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 310 PM CST Fri Feb 10 2017
20z/2pm surface analysis shows 1031mb high anchored over the
southeast CONUS...while a 997mb low tracks across northern
Minnesota. The pressure gradient between these two features
continues to provide brisk southerly winds across central Illinois
this afternoon...with wind gusts in the 25-35mph range. As the
pressure gradient gradually relaxes, winds will decrease to 10-15mph
early this evening...then will drop to less than 10mph overnight.
With diminishing winds and only high/thin cirrus overhead, the
potential will exist for fog development overnight...particularly
across the northern half of the KILX CWA where recent snow melt has
added copious amounts of moisture to the boundary layer. Latest
HRRR shows fog developing along/north of a Rushville to Danville
line after midnight.
With a frontal boundary settling southward into central Illinois,
winds will become light across the entire area during the day
Saturday. As additional moisture is advected northward across the
boundary, low clouds and fog will become widespread through the
afternoon. Forecast soundings indicate saturation from the surface
only up to about 900mb. Given the shallow boundary layer moisture,
think the chances for measurable precip are slim. As a result, will
only mention low chance PoPs for showers during the afternoon. Main
story will be the fog and drizzle...along with the warm
temperatures. High temperatures will mainly be in the upper 40s and
lower 50s...but will reach the upper 50s and lower 60s south of I-70
where southwesterly winds will persist the longest.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 310 PM CST Fri Feb 10 2017
Low pressure will pass across Illinois Saturday evening triggering
light rain. Very shallow moisture profiles might even support
drizzle instead of rain at times depending on how much isentropic
lift develops. Stronger lift would favor rain. The 12z models are in
decent agreement that the low will track roughly along I-70,
advancing into Indiana by midnight. The highest rain chances
continue to be focused east of I-57 during the evening, with precip
tapering off after midnight in the wake of the low.
The low departure will signal the arrival of colder air under
advancing high pressure, creating some non-diurnal temperature
swings across southeast IL on Sunday. Morning temps south of I-72
look to continue to drop a few degrees after sunrise on Sunday,
before beginning to rise again late morning into afternoon. Areas N
of I-72 should see a typical hourly temperature pattern, with rising
temps from sunrise into mid-afternoon. Despite the colder air, highs
should still climb above normal, with low 40s north of Peoria and
low 50s south of I-70.
The remainder of the extended looks to be free of precipitation as
the main weather maker in the southern stream drifts from the Four
Corners region due eastward toward the Gulf states, instead of
closer to Illinois. The northern stream system will pass north of
Illinois into the Great Lakes, dragging a dry cold front/trough
through Illinois on Tuesday. That push of colder air will drop temps
to around normal for Tuesday night through Wednesday night. With the
colder air in place on Wednesday, the 12z ECMWF continued its trend
of extending Lake Effect precipitation southward toward Vermilion
and Edgar counties. Have increase clouds a bit in that area, but
left precip out of Wednesday for now.
Gradual warming will prevail for the rest of the week, as southerly
winds develop later on Thursday and continue on Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 557 PM CST Fri Feb 10 2017
Southerly winds will diminish this evening as a boundary settles
closer to the area from the north weakening pressure gradients
over central IL. With the weakening surface winds...lingering
swift WSW flow aloft will allow for a period of low level wind
shear this evening...diminishing overnight as weaker winds
associated with a pressure trough aloft approach. With the lighter
winds moving in from the north and copious low level
moisture...fog potential will develop overnight particularly at
KPIA-KBMI. At this point...guidance suggests MVFR vsby. A low
pressure system tracking toward southern IL from the central
Plains will then bring copious low level moisture interacting with
the boundary across central IL to bring IFR ceilings, drizzle, and
fog after 12-17Z, particularly south of KPIA-KBMI. Winds at the
surface will be fairly light and variable from late in the night
through Saturday, but likely becoming predominantly E-NE toward
the end of the forecast period.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...37
SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...37
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1049 PM EST Fri Feb 10 2017
.UPDATE...
Issued at 1049 PM EST FRI FEB 10 2017
The mixing continues, as even the mesonet at Quicksand has
recovered sharply into the mid 50s. The latest satellite still
shows plenty of thinness upstream, especially south of the
Mountain Parkway, so will maintain the potential for the valleys
to cool off, in some cases once again through the 06z time frame.
UPDATE Issued at 859 PM EST FRI FEB 10 2017
South to southwest winds have kept things mixed in most locations,
with even a few places at their high for the day right now, like
the mesonet at Whitesburg, currently reporting 58 degrees. The
mesonet at Quicksand has exceeded cool expectations, having
dropped rapidly between 6 and 8 pm. They are currently reporting
37 degrees, with most other locations reporting anywhere from the
upper 40s to mid 50s. The surface pressure gradient looks to
slacken after 03z, and current satellite trends suggest still
fairly thin cloud cover in place. As such, will hold onto the idea
of decoupling, but just delaying it more until between 03 and
06z. Clouds will be on the increase between 06 and 09z, with
readings likely leveling off or even coming up once again. The
latest HRRR continues to support some potential light
precipitation along and west of the I-75 corridor towards 12z, so
will maintain the slight rain chances. Updates will be out
shortly.
UPDATE Issued at 653 PM EST FRI FEB 10 2017
The forecast is on track. Freshened up the hourly temperature drop
off through early this evening, based on the latest trends in
observations. Will have to see how well some of the valleys
decouple, as several hours of partly cloudy to mostly clear skies
look on tap and surface winds remain out of the south southwest.
For now, think that temperatures in the lower 40s look reasonable
for some of the cooler sites. Updates have been sent.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 325 PM EST FRI FEB 10 2017
A rather zonal pattern is in place from the Central to Eastern
Conus. At the surface, high pressure is shifting to the east of
the area while the pressure gradient has increased ahead of an
area of low pressure over the Plains. Temperatures have moderated
significantly since yesterday afternoon with most locations in
the 40s to lower 50s at this time in the warm advection pattern.
Dewpoints however have been slower to recover and are in the teens
to lower 20s. Winds have been a bit on the gusty side with gusts
as high as 15 to 20 mph. A shortwave trough is currently moving
across Ontario and the Great Lakes region while another shortwave
trough is moving across the Western Conus.
The Great Lakes shortwave will pass by well north of the area
tonight and into early on Saturday. Meanwhile, the northern
portion of the trough now moving across the Western Conus is
projected to quickly move across the Western US and reach the
Plains late Saturday and into Saturday night. The surface high
will continue to depart to the east and southeast of the area and
move off into the Atlantic tonight. Meanwhile surface low pressure
will gradually organize across the Plains tonight and into
Saturday before tracking into the Mid MS Valley and lower OH
Valley regions late Saturday and into Saturday night.
Return moisture will increase across the area tonight as the high
departs and ahead of the developing low pressure system over the
Central Plains. The pressure gradient will also be strong enough
to transport enough low level moisture into the area below 700 mb
for threat of light showers starting very late tonight and into
Saturday morning. The shower chances will persist through the day
on Saturday with the highest chances in the west. Shower chances
will be greater, however, on Saturday night as the surface low
passes by to the northwest of the area and a cold front and upper
level trough approach.
Temperatures will be on the mild side tonight as the pressure
gradient remains rather steep. However, some eastern valleys may
experience a period of lighter winds in the evening and a breif
decoupling. Some of the deeper valley temperatures were lowered
below model guidance blends but not nearly as low as the Coop MOS.
Low clouds will persist through the remainder of the period with
even milder temperatures on Saturday and little diurnal range into
Saturday night.
.LONG TERM...(Sunday through Friday)
Issued at 245 PM EST FRI FEB 10 2017
Models in decent agreement from Sunday into Tuesday. Looks like a
cold front will dive south across the area on Sunday with good
rain chances ahead of this boundary on Sunday. Temperatures will
then plunge behind the front for the start of the new week. High
pressure will bring moderating temperatures for the first part of
next week as it traverses the region.
The real complex part of the forecast comes Tuesday night through
Wednesday evening as we may see the northern and southern stream
start to interact with each other. The degree of interaction will
determine exactly how the weather plays out for the middle of the
week. The ECMWF has these two waves phasing completely over our
region generating a surface low that will track to our southeast.
This scenario would lead to high potential for accumulating snows
over some portion of our area, especially southeast Kentucky. The
GFS keeps these two systems separate with almost no phasing. That
scenario would likely keep us mainly dry. With this said, had to
include an extended period of pops from Tuesday night through
Wednesday evening to account for a potential phased system. Will
include a mention of snow in the HWO with the possibility of more
phasing. Another cold shot will follow on Thursday and have
undercut guidance significantly as highs will struggle to get much
above the mid 30s on Thursday. Looks like we may start to warm
again as we head into next weekend as the weather dries out again.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 653 PM EST FRI FEB 10 2017
Scattered mid and high level clouds will be seen through 06z,
before ceilings gradually lower through dawn, as a low level jet
ramps up across the Ohio Valley. Eventually, MVFR/IFR clouds will
develop and continue through the day on Saturday, with some
scattered light rain showers seen at times. Low level wind shear
will be prevalent through around 12z, with southwest winds of
between 5 and 10 kts at the surface continuing through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...JP
LONG TERM...KAS
AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
540 PM CST Fri Feb 10 2017
.SHORT TERM...(This evening through Saturday)
Issued at 347 PM CST Fri Feb 10 2017
Main concern for the short term is the cold front dropping south
in northern MN and the stratus behind it. This front will make it
down to about the Iowa border by Saturday morning, where it will
wash out. The HRRR shows this stratus spreading south through the
night, though even if we don`t get these low clouds, we will have
plenty of Pacific moisture streaming overhead through the night,
so we will at least have plenty of mid/upper level cloudiness.
The remnants of the front will then become a part of our one
chance for precip over the next week Sat afternoon into Sat
night. The Canadian/ECMWF show a band of precip developing to the
north of this boundary during the day Saturday, with the ARW,
NMM, and experimental HRRR showing a narrow band of precip
developing in either northern IA or southern MN as well. The
NAM/GFS both show issues with there being enough low level
moisture to allow for precip, so we have small chance pops down
there. Though it will be cooler in the wake of the cold front
tomorrow, we`ll still see highs get into the upper 30s, so p-type
with anything we see will be rain.
.LONG TERM...(Saturday night through Friday)
Issued at 347 PM CST Fri Feb 10 2017
The only chance for precip during the long term comes right out
the gate Saturday night. It will also remain mild, save for a
brief retreat in temperatures Wednesday thanks to a backdoor cold
front coming in Tuesday night.
The forcing for precip chances Saturday night will be driven by
the wave currently coming onshore in Washington. This shortwave
will be working across MN Saturday evening. The Canadian/ECMWF,
which have precip Sat afternoon, build that precip northeast into
western WI through the night, while the dry NAM/GFS remain dry.
Given the disagreements, continued low chance pops into Saturday
night. For p-type, have gone pretty simple, starting with rain and
transitioning to snow through the night as temperatures cool.
Like Saturday afternoon, QPF looks marginal, so any snowfall
amounts would be nothing more than a dusting.
For next week, there are no systems of much organization coming
across the upper Midwest, with the week looking to be dry
locally. Today, the GFS/ECMWF are both now showing a backdoor cold
front coming west out of the Great Lakes Tuesday night, this
looks to bring a brief pause in our thaw Wednesday, when
temperatures look to retreat back closer to or even a little below
normal. However, we`ve seen the models bounce around quite a bit
in the last couple of days with how far west this front will make
it mid-week, so our forecast is a bit warmer than what the 12z
GFS/ECWMF would say. This cool down will be short lived as both
the GFS and ECMWF show upper ridging building into central North
America by the end of the week, with h5 heights building to in
excess of 564dm in southern MN, so we`lllikely finish next week
with highs topping 50 for parts southern MN once again.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 540 PM CST Fri Feb 10 2017
An east-west cold front across northern MN this evening will slip
slowly south overnight. MVFR/IFR ceilings trail the front and
these ceilings will arrive into central MN after 06z and approach
the Twin Cities and western WI by daybreak Saturday. NAM 0.5 deg
CPD`s show the ceilings then lifting back ENE during the morning
and continuing in the afternoon at KRNH and KEAU. In addition,
due to the influx of low level moisture today, some restriction to
visibility is likely across central MN around daybreak with KAXN
likely the recipient of the lowest values. WSW winds this evening
5-10 knots becoming N 5 knots or less overnight and then WNW 5
knots for Saturday afternoon.
KMSP...Confidence not high on the IFR ceilings Saturday morning
but the timing of the ceilings in the wake of a weak cold front
during the morning where the best low level saturation is progged
makes sense. Improving conditions for the afternoon as the low
level winds back to the WSW pushing the low ceilings off to the
east.
/OUTLOOK FOR KMSP/
SUN...MVFR possible early. Wind NW 10 to 20 kts.
MON...VFR. Wind SW 10 kts.
TUE...VFR. Wind NW 10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
SHORT TERM...MPG
LONG TERM...MPG
AVIATION...RAH
Area Forecast Discussion
National Weather Service Norman OK
949 PM CST Fri Feb 10 2017
.UPDATE...
Updated hourly temperature/dewpoint forecast through 14Z to blend
with current observation trends. Otherwise, no significant
changes were made to the forecast.
&&
.DISCUSSION...
Similar to last night, the NAM12 and HRRR indicate that the
strongest winds will be along a northwest to southeast line from
Woodward to Oklahoma City to Seminole. These areas are expected to
stay the warmest tonight. Slightly cooler temperatures are
expected across north central and southwest Oklahoma, where the
winds will be lighter.
Either way, it will be a seasonably warm night with low temperatures
near average high temperatures for this time of year.
The 11/00Z NAM still indicates record setting temperatures for
tomorrow afternoon. The NAM is forecasting an 850 mb temperature
of ~22C at Norman (OUN) for 00Z tomorrow evening. To put this in
perspective, the record for the entire month of February
(according to the SPC Sounding Climatology Page) is 21.9C.
Mahale
&&
.PREV DISCUSSION... /issued 504 PM CST Fri Feb 10 2017/
DISCUSSION...
Please see the 00Z aviation discussion below.
AVIATION...
VFR will apply through the forecast period. Winds will remain
around 15 to 20 kt before sunset, and then decrease to around 15
kt or less overnight. A few high clouds are expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 54 87 43 54 / 0 0 0 10
Hobart OK 51 89 42 54 / 0 0 0 10
Wichita Falls TX 54 90 46 59 / 0 0 0 10
Gage OK 50 89 37 50 / 0 0 0 10
Ponca City OK 51 84 41 53 / 0 0 0 10
Durant OK 59 83 52 62 / 0 0 10 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Red Flag Warning from 11 AM to 7 PM CST Saturday for OKZ004>030-
033>040-044-045.
TX...Red Flag Warning from 11 AM to 7 PM CST Saturday for TXZ083>090.
&&
$$
10/03