Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/20/18
Area Forecast Discussion
National Weather Service Boston/Norton MA
1023 PM EST Mon Nov 19 2018
.SYNOPSIS...
Developing storm center tonight through Tuesday night will
bring accumulating snows mainly along and N of the MA-Turnpike,
impacting the Tuesday AM commute for some. Otherwise an all rain
or rain/snow mix. Colder weather follows for Wednesday into
Friday, with the possibility of some snow squalls Wednesday.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
1015 PM Update...
Front sitting well off our south coast. Regional radar shows
the heaviest band of precip draped northeast from Hartford
county to Essex county. Previous hi-res solutions showing a bit
of a lull behind the initial line are panning out well...seeing
a bit of a break behind the initial heavier precip. Obs in
Berkshire county show the snow from the past several hours has
stopped. In our area the only observation indicating snow at
this hour is KORE in north central MA, with rain at all other
observation sites. This matches up well with forecast over the
next several hours. No major changes. Most of the impacts from
this system are expected along and north of the MA pike.
Previous Discussion...
Main change with this forecast update is to speed to speed the
timing of the POPs, initial overruning precip is moving across
the area N of a BDL-ORH-BVY line with mixed RA and some SN in
the high terrain along the Berkshires. Watching trends suggest
this first round may actually dissipate in response to continued
deepening of the low pres upstream as it approaches. HRRR seems
to suggest this as well, so POPs will actually decrease a bit
initially until the stronger lift associated with the developing
frontal wave moves in during the early AM hours. Otherwise,
based on latest mesoscale guidance, see no need for significant
changes to snowfall amounts and headlines as they stand.
&&
.SHORT TERM /MIDNIGHT TONIGHT THROUGH TUESDAY NIGHT/...
Tonight through Tuesday...
Strengthening storm system across New England bringing accumulating
around 3-inch snows mostly N of the MA Turnpike, especially the high
terrain. Tuesday AM travel impacts with reduced visibility and snow
on area roadways for those areas noted.
Synoptically. Initial low sweeps New England with maturation further
downstream. Mainly open wave, not so much closed H925-85, tracking
over interior New England around the MA / VT / NH border, low level
convergent focus of the anti-cyclonic warm-moist conveyor belt out
ahead of a digging, sharpening mid-level trof axis and accompanying
vortmax energy. Initiated low to mid level thermal packing as well
as deformation / frontogenesis beneath mid-level ascent and initial
diffluence aloft, majority low-level forcing up thru the dendritic
growth zone, H6-7, so not impressively deep. Omega values through
the column weak, especially through the dendritic growth zone which
happens to exhibit some fairly steep lapse rates. Overall, a decent
front-end thump leading out ahead of the surface to H85 low. The
storm becomes better organized through Tuesday as it exits into the
Gulf of Maine having swept across the Cape Cod Canal around 1 pm.
Challenges. Thermal fields / thickness tell the story. Right on the
freezing cusp with deeper Arctic air absence N, hardly a N/NE high
over Canada. While N isallobaric flow, it`ll only drain S surface
temperatures ranging around 30 with dewpoints a tad lower such that
wet-bulbing can only do so much. Low-level column nearly isothermal
up through H8, warmer air intruding as the H925-85 flow flutters
along the MA / NH / VT border, possibly some drier air working in
through the dendritic growth zone, while fluttering around freezing
as the event evolves into the daylight hours, dealing with forecast
headaches concerning precipitation types and snowfall accumulations
as well as snowfall intensity. Speaking of, as model forecast mass
fields look pretty similar, small-scale focusing forcing mechanisms
vary as discerned via model forecast plume diagrams. Considerable
spread in respect to liquid-equivalent precipitation and snowfall,
the latter ranging from sub-advisory to warning levels in particular
locations. Relates back to snowfall intensity, some low probability
of 1"/hr noted in high-res guidance, and thermal field alignment as
to where the rain / snow cut-off line will be at any one particular
time. Forcing majority is, however, below the dendritic growth zone
with this synoptic setup. Of last note, model forecasts assume that
everything which falls accumulates on the ground which we know is
not always the case. So it`s definitely not easy but we`re going to
do our best as we always do.
Decisions. Despite uncertainties and challenges noted, a consensus
weighted forecast does not seem like a bad idea. Gave greater weight
towards the HREF blended within. With probabilities noted, and the
19.12z forecast suite slightly jogging S, focus is around the MA /
NH / VT border. Coating N of the MA-pike, with 1-3" lower elevations
while 3-6" higher, 500 feet and above especially. Potentially near
warning-level snows up around the N MA towns of Ashburnham, Ashby,
and Townsend. Keep with present N/W MA WINTER WEATHER ADVISORIES.
The storm center sweeping NE across the Cape Cod Canal important
with respect to blustery N/NE winds out ahead.
Impacts. Expect hazardous travel over N/W MA especially the higher
terrain of Worcester Hills and Berkshires. Route 2, western-half of
MA I-90, N MA I-95, I-190 out of Worcester, and the NW beltway of
495 all have the risk of accumulating snows on roadways. Reduced
visibility as well especially within any moderate to heavy snow as
near 1"/hr snowfall rates are possible. Thinking a very low risk of
any mixed wintry precip-types mainly in the form of freezing rain.
Tuesday night...
Turning colder and drier. The storm continuing to deepen into the
Gulf of ME, blustery NW winds follow. Some lingering snow showers
possible, especially for the high terrain. Otherwise the main storm
is the driving cold along with breezy conditions that`ll make it
feel 5 to 10 degrees colder than the forecast nighttime lows around
the low to mid 20s, possibly upper teens for the high terrain.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
4 AM update...
Highlights...
* Arctic front late Wed with snow squalls possible
* Near record cold & bitterly cold wind chills Wed night/Thanksgiving
* Moderating temps and dry Friday into Saturday
* Wintry weather possible Sunday
Overview and model preferences...
The longwave trof which has been a persistent player in the
daily sensible wx across the northeast finally gets a break
later this period, but not before one last push of cold air. Two
mid lvl cutoffs Fujiwhara near Hudson`s Bay with one and its
attendant vort-max sliding close to New England Wed into Thu.
The surface reflection is an arctic cold frontal passage Wed.
This ushers in a very anomalous airmass with H85 temps nearly
-20C below seasonal normal values which will be with us for
Thursday into Saturday. Upper lvl ridge finally shifts E,
shifting the trof offshore by the weekend. However, it too
flattens as a second wave, linked more closely to the southern
stream per latest guidance moves in late weekend into early next
week. Given the guidance has been in fairly good agreement with
this arctic influenced pattern a consensus blend will be used
except for temperatures, which will feature the coldest of the
guidance Wed-Fri.
Details...
Wed...
Arctic cold frontal passage linked to acute, cyclonically-
curved shortwave rotating through the base of the longwave trof
mentioned above. The main issue will be the risk for snow
squalls. Soundings indicate a sfc-H7 which is both moist and
with potentially higher than dry-adiabatic lapse rates. With
this implied instability, cold air aloft and strong dynamic
cooling in play, could very well see brief bursts of heavy snow
impacting commuters. LLJ at the top of this well mixed layer is
around 40 kt, which could mix down some of this momentum to
accompany the snow. Hence the risk for squalls, this will be
something to watch given the typically busy travel day.
Thu...
Core of cold air working E but as nearly 1040mb high pres and
deepening low pres in the Maritimes combine to yield strong
pres rises note very breezy 20-30 kt winds at times as well.
Ambient mixed temps will struggle to break out of the teens and
low 20s, but with winds, expecting chill values int the single
digits to near 0F. With pres gradient weakening late Thu night,
some radiational cooling should allow ambient 2m mins to drop
into the single digits as well. Ocean effect SN for the outer
arm of the Cape particularly thanks to +15C SST-H85 delta-T
values.
Fri and Sat...
Core of high pres slides across New England with the
continuation of dry wx. Temps moderate but remain well below
normal on Fri, with highs only making it into the upper 20s to
low 30s. Overnight mins still cold given good setup for
radiational cooling once again. Highs moderate further Sat,
reaching the low-mid 40s thanks to increase in mid lvl temps.
Sun into Mon...
Will be monitoring low pres development in convection near the
Gulf of Mexico, linked to a S stream shortwave. The track of
this feature is still uncertain given wide model spread and the
features not well sampled at this time. This will dictate
whether its an inland passage (warmer solution) or offshore
track (colder, but also a risk for a miss). Exact p-type details
will be worked out with time.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Tuesday Night/...High Confidence.
Tonight and Tuesday...
Mainly VFR vsby with mixed MVFR/VFR CIGS through about 04Z
south of a line from BDL-ORH-BVY. Areas N will mix MVFR/IFR in
light RA/SN through this time. After 04Z, trend will be toward
mainly IFR all sites except immediate S coast due to lowered
CIGS. VSBYS MVFR/IFR in SN mainly along and N of the Mass Pike
with RA to the S. This continues into Tue with some improvement
after 18Z, slowly from W-E. Winds N-NE.
Tuesday night...
Winds shifting NW as conditions improve towards VFR, the 18z
storm center lifting out into the Gulf of ME. Gusts up to around
25 kts possible especially over the high terrain and along
coastline terminals.
KBOS Terminal...
Moderate confidence, mainly due to uncertainty in timing of
lower categories/precipitation. VFR conditions to gradually give
way to MVFR then IFR with lowered CIGS then vsbys as a mix of
RA/SN develops late tonight. Mainly RA into tomorrow but a brief
change back to SN is possible late tomorrow afternoon before the
precip ceases entirely.
KBDL Terminal...
VFR gives way to mixed MVFR then IFR within the next 3-4 hours.
RASN mix right through the Tuesday morning push, becoming all
rain towards midday. Mostly IFR, improving MVFR to VFR late
Tuesday into Tuesday evening. N winds throughout shifting NW
late. Somewhat breezy, especially late with potential gusts up
to 20 kts.
Outlook /Wednesday through Saturday/...
Wednesday: Mainly VFR, with local IFR possible. Windy with
gusts to 35 kt. Isolated SHSN.
Wednesday Night through Thanksgiving Day: VFR. Windy with gusts
to 35 kt.
Thursday Night: VFR. Windy with areas gusts to 30 kt.
Friday: VFR.
Friday Night: VFR. Breezy.
Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA or
SHSN.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Tuesday Night/...High confidence.
Storm center passing over the Cape Cod Canal around 18z Tuesday.
Will see increasing E/NE winds out ahead especially over the E
waters, S/SW for the S waters. Behind the storm center, winds
turning NW, remaining blustery. Throughout, gusts up around 25
kts possible. Can`t rule out near gale force gusts. SMALL CRAFT
HEADLINES in effect for the later-half of Tuesday going into
Tuesday night as seas build up around 5 to 7 feet on the outer
waters.
Outlook /Wednesday through Saturday/...
Wednesday: Low risk for gale force winds with gusts up to
35 kt. Seas up to 5 ft. Isolated snow showers. Local visibility
1 to 3 nm.
Wednesday Night: Moderate risk for gale force winds with gusts
up to 40 kt. Rough seas up to 10 ft. Isolated snow showers.
Areas of visibility 1 to 3 nm.
Thanksgiving Day: Strong winds with gusts up to 35 kt. Rough
seas up to 10 ft. Isolated snow showers. Areas of visibility
1 to 3 nm.
Thursday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Local rough seas. Local visibility 1 to
3 nm.
Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Friday Night: Winds less than 25 kt.
Saturday: Winds less than 25 kt. Slight chance of rain showers.
&&
.CLIMATE...
With the potential of the coldest air of the season moving into
the region around Thanksgiving, here are the record temperatures
for November 22nd and the holiday of Thanksgiving.
November 22nd
Location / Record Low / Record Minimum High
Boston..........9 (1879) / 24 (1880)
Hartford.......14 (1969) / 27 (1978)
Providence.....16 (1987) / 30 (2008)
Worcester......11 (1987) / 24 (2008)
Thanksgiving
Location / Record Low / Record Minimum High
Boston.........11 (Nov 27, 1873) / 24 (Nov 28, 1901)
Hartford.......12 (Nov 28, 2002) / 27 (Nov 23, 1989)
Providence.....14 (Nov 23, 1972) / 30 (Nov 28, 1996)
Worcester.......9 (Nov 23, 1989) / 22 (Nov 23, 1989)
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Weather Advisory until 5 PM EST Tuesday for MAZ002>004-
008-009-026.
RI...None.
MARINE...Gale Watch from Wednesday evening through Thursday morning for
ANZ231>234-251.
Small Craft Advisory from 4 PM Tuesday to 4 AM EST Wednesday
for ANZ232>234.
Small Craft Advisory from 1 PM Tuesday to 1 AM EST Wednesday
for ANZ231-251.
Gale Watch from Wednesday afternoon through Thursday morning
for ANZ235-237.
Small Craft Advisory from 4 PM Tuesday to 6 AM EST Wednesday
for ANZ235-237.
Gale Watch from Wednesday afternoon through Thursday evening
for ANZ250-254>256.
Small Craft Advisory from 10 AM Tuesday to 6 AM EST Wednesday
for ANZ250.
Small Craft Advisory from 1 PM Tuesday to 6 AM EST Wednesday
for ANZ254>256.
&&
$$
SYNOPSIS...Doody/Sipprell
NEAR TERM...Doody/BW
SHORT TERM...Sipprell
LONG TERM...Doody
AVIATION...Doody/Sipprell
MARINE...Doody/Sipprell
CLIMATE...
Area Forecast Discussion
National Weather Service Hastings NE
559 PM CST Mon Nov 19 2018
.SHORT TERM...(This evening through Tuesday)
Issued at 350 PM CST Mon Nov 19 2018
Aloft: WV imagery/upr-air data and aircraft obs showed a highly-
amplified longwave pattern over the CONUS...with a ridge in the W
and a broad trof extending from Hudson Bay to OK. Thru tomorrow
these features will move E and deamplify a bit. So NW flow will
remain over the Cntrl Plns with heights rising about 80 m at 500
mb.
Surface: Weak low pres was over MI with a cold front extending
back across IA thru the Neb Sandhills then NW into Wrn Canada.
This front will briefly sag SW into the CWA tonight. However...a
weak Clipper will slide down the front to near Lk Winnipeg tonight
and then into the GtLks tomorrow. As a result...the front over
the CWA will move E out of the CWA as a warm front tomorrow
morning. Meanwhile...high pres was over ND at 20Z and it will
slide SSE across Ern Neb/KS tonight.
Now thru sunset: P-M/cldy. Temps overachieved today...but they
have leveled off with the increased cld cover.
LNX radar showed some spotty light returns over the Sandhills...
and ANW did report some sprinkles. Can`t discount a few sprinkles
moving into areas N and W of the Tri-Cities as these returns are
moving SSE.
Tonight: Quite a bit of uncertainty for period 1 of the fcst.
Multi-model cross sections show a lot of RH below 10K ft
suggesting that stratocu will hang around thru much of the night
for parts of the CWA. Unusual as at least some of this is
diurnally driven.
Should be another cold night with lows mostly 19-24F.
Areas of fog could be a problem. There is quite a bit of spread
between mdls that are fcstg fog and those that are not...and am a
bit uncomfortable that the mdls that usually handle fog the best
(GFS MOS and LAMP) don`t have it. That being said...conds appear
favorable. Dwpts are in the low-mid 30s and temps are fcst to
crash way past the cross-over temps. The developing warm front is
also a concern.
For now...used vsbys from consensus of short-term mdls to include
fog W of Hwy 281 mainly over S-cntrl Neb. Keep in mind there is
considerable uncertainty in coverage and how low vsbys might be
(if fog actually forms). This could be a serious weakness in this
fcst.
Tue: If any fog develops...it could take most of the AM to
dissipate given the low sun angle. Otherwise sunny...or becoming
sunny.
Warmer with temps rebounding to a little above normal (mostly
50s).
.LONG TERM...(Tuesday night through Monday)
Issued at 257 PM CST Mon Nov 19 2018
Aloft: The longwaves will cont to be progressive thru this wknd.
The last 2 runs of the EC/GFS/GFS-parallel/GEM/UKMET all fcst the
ridge over the Rckys to crest over the Cntrl Plns Thu AM. The trof
currently over the E Pac will be making its way E and will arrive
here Fri AM. That trof will establish a longwave trof over the
Cntrl USA thru the wknd. A low is fcst to drop out of the GlfAK
and arrive here Sat-Sun where it could deepen over OK or KS.
There is a lot of spread in how the mdls are handling that Sat-
Sun system. The 00Z/12Z EC and 12Z/UKMET are the strongest with a
closed low. The 12Z GFS-parallel is also in that camp. The 06Z/12Z
GFS and 00Z/12Z GEM keep the trof open. See below for commentary
on the sensible wx.
Surface: The CWA will remain in the warm sector Wed-Thu. A Pac
cool front moves thru Fri. An Arctic front will then plunge S out
of Canada Sat while lee cyclogenesis begins over CO. That front
should arrive Sat night and wrap into the low ejecting out of CO.
High pres will build in Mon as this low heads across the GtLks.
Temps: About 10F above normal Wed-Fri for daytime highs which
translates to widespread 50s..and even some low 60s W of Hwy 183.
Back to normal Sat...then 10-15F colder than normal Sun-Mon with
highs in the 30s.
Precip: A bit of light rain possible Thu night into Fri ahead of
the cool front. Some light rain is possible Sat changing to snow
Sat night.
Could we have a winter storm (accumulating snow) Sat night into
Sun? It`s possible. The op EC remains the most aggressive with
this scenario. However...only half of the 00Z EC ensemble members
bring accumulating snow to the CWA. So even though the op runs
are aggressive...there are many ensemble members that are not.
How this sys evolves aloft will have major implications on the
fcst...and possibly important impacts for holiday travelers
returning to the rgn Sun.
Suggest everyone pay attention to the wx and monitor future
fcsts.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 555 PM CST Mon Nov 19 2018
Confidence is lower than normal on ceiling and visibility
conditions late tonight into Tuesday morning given the
possibility of fog. The SREF is showing a pretty good chance for
fog especially from KEAR west, but the HRRR has not been showing
much fog potential. Will call for VFR conditions for now with
limited confidence, but if fog does develop this TAF will need
some big adjustments.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Green Bay WI
533 PM CST Mon Nov 19 2018
Updated aviation portion for 00Z TAF issuance
.SYNOPSIS...
Issued at 222 PM CST Mon Nov 19 2018
Rather quiet but chilly weather will continue through Thanksgiving
Day, with minimal weather-related problems expected as holiday
travelers head out across the area. Warmer weather is expected for
the rest of the holiday weekend, with an increasing chance for
precipitation as well.
The upper flow across North America will become progressive as
flattening flow to the west allows Pacific energy to drive
eastward across the continent. The change will initially lead to
a less amplified and more zonal flow by the weekend. But that is
expected to transition into a highly split flow regime over
central and eastern North America next week.
Temperatures will remain below normal for a couple more days,
begin to warm on Thanksgiving, then spend at least a couple days
above normal. The developing split flow next week is likely to be
characterized by strong blocking over eastern Canada. That will
probably lock a southern stream trough in over the Great Lakes
region, forcing temperatures back below normal by the end of the
period. Little consequential precipitation is expected until the
weekend, when a complex/disjointed looking system is likely to
bring widespread light to perhaps moderate precipitation to the
area. At least initially, temperatures will probably be mild
enough for primarily rain in the south and rain or a wintry mix in
the north. The best estimate is for near or slightly below normal
precipitation amounts for the period.
&&
.SHORT TERM...Tonight and Tuesday
Issued at 222 PM CST Mon Nov 19 2018
The latest RAP analysis and satellite/radar imagery show an area
of low pressure moving east over northern Lower Michigan, and an
associated cold front exiting east-central WI early this
afternoon. Light snow associated with the system has departed to
the east. Meanwhile, after a brief period of clearing right behind
the front, boundary layer instability combined with moisture
fluxes off Lake Superior are pushing additional cloud cover south
over much of the area. Some flurries or light snow showers will be
possible over far northern WI through the end of the afternoon.
Until the next weak clipper arrives on Tuesday afternoon, forecast
concerns mainly revolve around clouds and temps.
Tonight...North flow will continue through the evening behind the
low pressure system. With loss of diurnal instability, think
gradual clearing will take place over parts of central and
northeast WI, but delayed it until late evening and overnight.
However, north- central WI will likely have to wait until
late tonight or into Tuesday morning for clearing to occur when
winds back around to the west and allow for some drier air to push
into that area. Will keep isolated to scattered snow showers in
the forecast for Vilas county due to lake effect. Boundary layer
winds will lighten through the night, and if any clearing occurs
across the north, think temps have potential to tank. But given
the expansive blanket of clouds, stayed conservative with temps.
Lows expected to range from the mid single digits north to the
upper teens near the Lake.
Tuesday...Scattered to broken low clouds may linger over far
northern WI for a few hours in the morning. Otherwise, the surface
ridge axis will quickly move across the area into early afternoon,
which should result in some sunshine over eastern WI. However,
clouds will be rapidly returning ahead of the next clipper and
cold front which will be moving into northwest Wisconsin in the
afternoon. Moisture is extremely limited, but most models generate
about a half inch of snow for the northwoods during the
afternoon. Some slippery roads are possible, mainly over Vilas
and Oneida counties. Highs are forecast to range from the lower
20s north to the lower 30s over the southern Fox Valley.
.LONG TERM...Tuesday Night Through Monday
Issued at 222 PM CST Mon Nov 19 2018
With the large scale pattern becoming progressive, the best
forcing with the system digging southeast from Canada Tuesday
night will pass north of the area. Continued similar to the
previous forecast in having chance PoPs in the north into the
evening, with a period of lake-effect likely in the Lake Superior
snowbelt overnight as the system pulls off to the east. It still
appears possible that a little FZDZ could occur as the system
departs and moisture becomes increasingly shallow.
Models seem to be picking up on the possibility of some lake-
effect off Lake Michigan affecting the east Wednesday night and
Thursday morning as winds shift around to the east. But a very
strong inversion around 850 mb should prevent anything more than
flurries or light snow showers.
The medium range models continue to struggle discerning the
details of the system or series of systems likely to affect the
area during the weekend and early next week. The flow will be
starting to separate as the split becomes more pronounced. That is
likely to keep the best southern stream dynamics and moisture
south and east of the area. There will probably be a few rounds of
light precipitation, the last of which may be a prolonged period
of light snow or snow showers early next week as an upper trough
gets locked into the Great Lakes region.
Overall, no significant changes were necessary to the standard
forecast initialization grids.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 533 PM CST Mon Nov 19 2018
Abundant cloud cover will continue across the western Great Lakes
this evening behind a cold front. Some LES showers will continue
across the north this evening, before diminishing later tonight.
Some drier air is forecast to clear skies out later tonight across
central and east-central Wisconsin as ridging makes its way in
from the west. Skies across the north should remain mostly cloudy
throughout the period. There is some question as to when the
clearing will take place as not all models clear the area out
later tonight into Tuesday morning. If the clearing does occur it
will cloud back up Tuesday afternoon as another clipper system
tracks through the western Great Lakes region. This clipper system
could bring some light snow or even some freezing rain, mainly
across north- central and central Wisconsin. At this point will
leave out the freezing drizzle potential as it is fairly low with
this issuance.
MVFR cigs are expected across the north through tonight, then
briefly rising to VFR later Tuesday morning into the early
afternoon before falling again to MVFR. Further south mainly VFR
conditions are expected through the period, with some MVFR
possible early this evening.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....MPC
LONG TERM......Skowronski
AVIATION.......Kurimski
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1043 PM EST Mon Nov 19 2018
.SYNOPSIS...
Weak low pressure will track east along a stalled frontal
boundary over southern New England late tonight through
Tuesday. Low pressure will continue east into the maritimes
Tuesday night. An arctic front will drop south through the
region on Wednesday. A strong northwest flow will set up behind
the front Wednesday night and Thursday. High pressure will build
in from the west Thursday night and will crest over the region
on Friday. High pressure will shift offshore Friday night and
will hold there through Saturday. A warm front will approach
from the south Saturday night and Sunday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Update...RAP H9 to H8 frontogenesis continues to best describe
areal coverage of radar echoes at this hour. I have adjusted PoP
to match that field. The RAP forecast is for that forcing to
move very little N or S thru morning...but rather slide Ewd on a
parallel line. So I have PoP increasing along that line and
gradually increasing in area as low pressure develops. Otherwise
no major changes.
Previous discussion...Weak surface wave riding along stalled
frontal boundary sitting offshore early this afternoon will
continue east into the maritimes this evening. Lingering rain or
snow showers in midcoast areas should be coming to an end by
late afternoon.
Precipitation ahead of the next wave already edging into the
lower Hudson Valley and expect occasional light rain or snow
showers to brush southern New Hampshire zones during the evening
hours with little if any accumulation. Looking for steadier snow
to shift into southern New Hampshire after midnight...
overspreading the remainder of the forecast area after daybreak
Tuesday.
Have issued Winter Weather Advisories for southern New
Hampshire for late tonight through Tuesday afternoon. Advisories
in coastal and southern interior portions of Maine kick in
around 10Z and go into the early evening. Generally looking for
a 3 to 6 inch snowfall in these areas with the bulk of that
during the daylight hours Tuesday. Some indications of a mix in
the far south and coastal areas during the day Tuesday which may
hold down amounts in those areas. Farther north...2 to 4 inches
will likely cover the mountains and foothills. High temperatures
will range from the mid 20s north to the mid 30s south.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Update...Latest model guidance remains in excellent agreement on
placement of H8 frontogenesis during the day Tue. With the
expectation for the heaviest precip to fall just on the cool
side of that forcing...that places Srn interior NH and coastal
Wrn ME in the prime spot for a high end advisory snowfall. One
thing I am keeping an eye on is the trend for models
transitioning from an open wave at H8 to a closed low in the
Gulf of ME. That is giving some signals for more concentrated
band of snowfall across coastal Wrn ME during the afternoon Tue.
This is most notable on the GFS...RGEM...and ECMWF
solutions...and in good agreement with extended HRRR snowfall
algorithms.
Previous discussion...Have issued Winter Weather Advisories for
southern New Hampshire for late tonight through Tuesday
afternoon. Advisories in coastal and southern interior portions
of Maine kick in around 10Z and go into the early evening.
Generally looking for a 3 to 6 inch snowfall in these areas with
the bulk of that during the daylight hours Tuesday. Some
indications of a mix in the far south and coastal areas during
the day Tuesday which may hold down amounts in those areas.
Farther north...2 to 4 inches will likely cover the mountains
and foothills. High temperatures will range from the mid 20s
north to the mid 30s south.
Low pressure will race east into the maritimes Tuesday night
with snow ending in far eastern zones during the evening hours.
Downsloping winds behind the low will bring partial clearing
overnight. Lows will range from the mid teens north to the mid
20s south.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Arctic cold front comes crashing through the forecast area on
Wednesday, particularly during the afternoon. This arctic front
may herald in the coldest air mass we have seen on Thanksgiving
on record. But first, the airmass along the front will be
conducive to snow squalls. Given the current timing of the
front, the most likely time frame for these will be during the
afternoon hours and may cause brief locally dangerous driving
conditions due to low vsbys in heavy snow along with quickly
slickening road conditions. Not a good combination on the
busiest travel day of the year. Not everyone will see one, but
brief whiteout conditions are quite possible for those that do.
In addition, a weak area of low pressure may accompany this
front - likely moving across central or northern zones. There
may be enough ascent with this feature to drop a couple inches
of snow north of the low track. Have accounted for this
possibility in our snowfall grids. Otherwise, the coldest air we
have likely seen in any recorded November will arrive in the
wake of the front. Highs will likely remain in the teens during
the daylight hours on Thanksgiving day with wind chills around
if not below zero the vast majority of the forecast area.
High pressure crests over the region Friday into Saturday giving
us warmer and less windy weather. Thereafter, several short wave
troughs ejecting out of the central states may affect our region
early next week. As of right now, these could be rain events
after starting as a mix - both Saturday night/Sunday and again
around Monday/Tuesday. However, solutions are likely to change
going forward at this juncture.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
Short Term...MVFR/IFR ceilings this evening. IFR/LIFR
ceilings/vsby developing after midnight and persisting through
Tuesday. Becoming VFR Tuesday night with areas of MVFR ceilings
in the north.
Long Term...Local IFR conditions in snow showers and snow
squalls Wednesday afternoon followed by VFR conditions (MVFR
mountains) Thursday. Winds Wed night and Thu likely gust around
30 kt from the NW. VFR Friday and Saturday with lighter winds.
&&
.MARINE...
Short Term...Have issued SCA`s for the outer waters Tuesday.
Long Term...A strong cold front will move across the forecast
area Wed afternoon or early evening. Gales are possible if not
likely in the wake of the front Wednesday night through
Thursday. A gale watch has been posted.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory from 5 AM to 7 PM EST Tuesday for
MEZ018>028.
NH...Winter Weather Advisory from 2 AM to 5 PM EST Tuesday for
NHZ006>015.
MARINE...Gale Watch from Wednesday afternoon through Thursday evening
for ANZ150-152-154.
Small Craft Advisory from 7 AM to 10 PM EST Tuesday for ANZ150-
152-154.
&&
$$
NEAR TERM...Legro
Area Forecast Discussion
National Weather Service Lincoln IL
738 PM CST Mon Nov 19 2018
.UPDATE...
Issued at 737 PM CST Mon Nov 19 2018
Cold front is showing up on radar from Jacksonville to Bloomington
at 730 pm. Scattered sprinkles and flurries began to develop
around sunset and have picked up on both sides of the front, so
the forecast was recently updated to include a mention in areas
north of I-70 this evening. Temperatures ahead of the front have
not fallen off quite as fast as first thought, but overall low
temperatures still look good.
Updated grids/zones have been sent.
&&
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 245 PM CST Mon Nov 19 2018
Weak cold front over far northwest Illinois will move across our
area this evening bringing another band of cloudiness southeast
into central Illinois. Short term models continue to suggest the
better lift and moisture will be to our north and northeast
tonight but the last few runs of the HRRR model indicated some
isolated rain and snow showers possible over our far eastern
counties this evening. Otherwise, dry weather is expected
overnight as winds shift into the northwest bringing in another
chilly air mass with temperatures to our northwest this afternoon
having a tough time getting out of the middle 20s. We won`t see
anything that cold but a definite chill will be in the air late
tonight with lows dipping to near 20 north to the upper 20s south
of I-70.
High pressure will settle south into the Midwest on Tuesday with
forecast soundings indicating a strengthening subsidence inversion
which may effectively trap the low level moisture/clouds on Tuesday
keeping the cloud cover across the area longer than currently
forecast, especially over the east. Will go with a gradual decrease
in cloud cover from northwest to southeast during the late morning
and early afternoon hours, but confidence not that great on that
happening based off some of the forecast soundings. Temperatures
mostly in the 30s for daytime highs tomorrow.
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 225 PM CST Mon Nov 19 2018
Chilly weather to hold across the forecast area into Wednesday
morning before the pattern begins to shift over the lower 48
as the deep upper low across the upper Great Lakes shifts well
off to our east, while an upper low settles across the southern
Rockies. This should allow more of a west to southwest flow
pattern to develop and bring warmer air into the Midwest for
the second half of the work week. Temperatures by Wednesday and
Thanksgiving day should moderate into the mid 40s to near 50
degrees with afternoon temperatures around 50 on Friday and
the start of the weekend Saturday before we see a cool down
starting Sunday.
As the longwave trof repositions itself across the southern
Rockies late in the, models depict several shortwaves ejecting
across the Plains and into the Midwest bringing an increasing
chance for rain in our area starting on Friday. Unfortunately,
it appears we will have periodic chances for rain into the
weekend and depending on the exact track of the second wave
forecast to come out of the southern Plains later Sunday, there
could be a rain/snow threat Sunday night into Monday, with any
snow chance mainly across our far north based on the latest
track of the surface low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 536 PM CST Mon Nov 19 2018
TAF sites have improved to VFR conditions early this evening,
though there`s some concern that ceilings will regress as the low
level inversion strengthens tonight. Have gone with MVFR
conditions at most sites overnight, though KSPI is more on the
fringe and went with a TEMPO period this evening, as a front
passes. East central Illinois may take until early afternoon
Tuesday to see a significant improvement.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Geelhart
SHORT TERM...Smith
LONG TERM...Smith
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Jacksonville FL
921 PM EST Mon Nov 19 2018
...MILD LOW TEMPS AND AREAS OF FOG AGAIN TONIGHT...
.UPDATE...
Low stratus was settling to the surface as fog already this
evening across SE GA as temps/Tds cool into the low/mid 50s under
a surface ridge axis bringing calm winds. HRRR continued to
resolve this scenario well with advection fog expanding SSW and
filling in across SE GA through the early morning hours, with
another dense fog advisory probable for at least SE GA and
portions of NE FL near the I-10 corridor. A few hours before
sunrise, HRRR trends suggested fog actually scouring out across
our NW GA zones from Jesup toward Douglas as low level mixing
increases ahead of weak surface front sliding south across GA
overnight. Issued a Special Weather Statement (SPS) for all of SE
GA and the I-10 corridor of NE FL to alert of fog development
tonight, with periods of patchy dense expected (dense fog defined
as visibility < 1/4 mile).
Farther south across the remainder of NE FL, dew pt depressions
were larger and the airmass was more mixed due to proximity of a
weak surface trough across central FL. Through the night, expect
more patchy intermittent radiation fog across our southern FL
zones where SREF guidance indicated more passing low/mid clouds
downstream of mid level short wave trough. CAM guidance indicate a
few spotty showers possible after midnight moving across our NE FL
zones associated with the mid level short wave trough and
convergence near the lingering surface trough across central FL,
and trended rain chances at 14% or less for areas along and south
of St. Augustine to Ocala.
Temperatures will trend a bit cooler than last night with low in the
low/mid 50s inland (upper 40s in normally cooler locales) to near
60 toward the Atlantic coast.
&&
.AVIATION...
Restrictions to IFR or lower most probable at JAX, VQQ and CRG
tonight, with MVFR conditions advertised after 08Z for SSI, SGJ
and GNV. Low potential for passing sprinkle/light showers near GNV
and SGJ early Tue morning, but probability too low to include in
TAF at this time. Weak front will slide south of the area through
Tuesday with prevailing VFR conditions by early afternoon and WNW
winds 10 kts or less.
&&
.MARINE...
Light and variable winds over the waters for much of the evening
as a weak high pressure ridge axis extends overhead. Winds will
transition to more NNW after midnight with winds 10 kts or less.
Combined seas 2-4 ft. A few spotty showers possible after midnight
as a weak upper level disturbance moves over the area from the
west.
Rip Currents: Moderate NE FL Tue. Low risk SE GA Tue.
&&
.HYDROLOGY...
The Altamaha River at both Charlotteville and Baxley is forecast
to rise into minor flood through mid-week. River flood warnings
remain in effect.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 52 71 41 64 / 10 10 0 0
SSI 58 71 48 65 / 10 10 0 0
JAX 56 73 47 68 / 10 10 0 0
SGJ 60 73 53 70 / 10 10 0 0
GNV 58 74 47 70 / 10 10 0 0
OCF 60 76 49 72 / 10 10 0 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Enyedi/Kennedy