Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/06/18
Area Forecast Discussion
National Weather Service Caribou ME
1019 PM EST Fri Jan 5 2018
Low pressure will track across Labrador tonight through
Saturday. High pressure will build south of the area Saturday
night into Sunday.
.NEAR TERM /THROUGH SATURDAY/...
10 P.M. Update...Its getting cold out for sure once again, and
the winds are not helping. Wind chill advisories and warnings
are still in good shape, might need to extend the headlines a
little longer into tomorrow. Light snow across the crown is
currently occurring, and could reach as far south as Presque
Isle tonight but expected to make it much further.
700 P.M. Update...Forecast is in good shape overall, just
tweaked the temps a little with this update. Wind chill
headlines look good as temps drop tonight and winds haven`t
weakened much as pressure gradient remains tight over the area,
still about 15mb MSLP across the state. HRRR and NAM are still
showing some light snow rotating back into the Crown of Maine
tonight, so have kept the chance for light snow. There are some
light returns currently on the radar which we are picking up via
Canadian radars. Should only be a dusting to a half an inch of
fluff at the worst.
The powerful storm which brought our blizzard Thursday night
will very slowly continue to lift northeast and away tonight
into Saturday. The gradient behind the low combined with high
pressure pushing in from the west will continue to produce gusty
westerly winds as bitter cold arctic air filters into the
region. A few snow showers will likely continue over
northwestern areas tonight. Otherwise, tonight will be mainly
dry with some patchy blowing snow continuing. The combination of
cold arctic air and gusty winds will require wind chill
warnings for northwestern zones and wind chill advisories for
the rest of the area tonight through Saturday morning.
Otherwise, Saturday will be mostly cloudy with a few snow
showers across the north. High pressure building southwest of
the area combined with some clearing Saturday night will bring a
frigid night with lows dropping from the 20s below over the
northwest to the teens below over much of Downeast. Clouds will
increase Sunday as low pressure moving through central Canada
lifts a weak warm front into the area. Some light snow is
possible across northwestern areas late in the day.
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
High pressure will exit across the maritimes Sunday night, with
a warm front approaching late. Expect mostly cloudy skies along
with a chance of snow across the forecast area Sunday night.
The warm front will cross the region Monday keeping mostly
cloudy skies along with a chance of snow across the region.
Temperatures will be at slightly below normal levels Monday.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A cold/occluded front will cross the region Tuesday with a
chance of light snow or snow showers. High pressure will cross
the region early Wednesday then exit to the east late with a
return flow of warmer air developing. The warm return flow will
persist Thursday in advance of an approaching cold front,
allowing snow to transition to a wintry mix or rain. Uncertainty
still exists regarding specific precipitation types and amounts.
The cold front will then cross the region Friday with the
wintry mix and rain ending in the wake of the cold front. Above
normal level temperatures are expected Tuesday/Thursday/Friday,
with below normal level temperatures Wednesday.
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
NEAR TERM: MVFR conditions in variable low clouds and some
blowing snow will continue across the north through Saturday
morning with VFR conditions expected Downeast. VFR conditions
are expected late Saturday into Sunday. However, conditions may
lower to MVFR across the north in lower clouds and some light
snow late Sunday.
SHORT TERM: MVFR conditions will develop across the region
Sunday night. MVFR/IFR conditions are then expected Monday, with
VFR/MVFR conditions early Tuesday. Generally expect VFR
conditions Tuesday night through much of Wednesday, with MVFR
conditions developing later Wednesday.
NEAR TERM: A gale warning and heavy freezing spray warning will
be up tonight into Saturday with strong gusty winds pulling
frigid Arctic air over the waters. Winds will gradually diminish
later Saturday into Sunday although a SCA will likely be
required following the gale warning through Sunday.
SHORT TERM: Small craft advisory conditions are expected Sunday
night/Monday along with light freezing spray. Visibilities could
be reduced in snow later Sunday night into Monday.
ME...Wind Chill Advisory until 11 AM EST Saturday for MEZ002-005-
Wind Chill Warning until 11 AM EST Saturday for MEZ001-003-004-
MARINE...Heavy Freezing Spray Warning until 3 PM EST Saturday for
Gale Warning until 7 PM EST Saturday for ANZ050>052.
Area Forecast Discussion
National Weather Service Melbourne FL
914 PM EST Fri Jan 5 2018
The main forecast challenges for the overnight period continue to
be the threat for sub-freezing temperatures and how much
radiational cooling will be seen. IR satellite continues to show
a steady stream of higher clouds moving over central Florida from
the Gulf, which will prohibit effective effective radiational
cooling. Latest RAP soundings indicate these high clouds will
stick around for much of the night with the best chance of some
clearing over northern areas late tonight. Light winds and lower
dewpoints will promote temperatures to drop off quickly once there
is enough clearing. Inherited forecast and freeze warnings for
Lake and Volusia counties look good with lows of 29 to 32 degrees.
Farther to the south, where there is more cloud cover forecast,
temperatures will stay a bit "warmer" but still quite cold. Areas
along and south of the I-4 corridor will see low temperatures in
the 33 to 35 degree range and a couple of degrees of warmer closer
to the coast. The immediate Treasure Coast will see lows in the
mid to upper 30s and even low 40s in Martin county.
Tonight(previous)...North winds around 15 knots will continue to
produce choppy seas up to 6 feet in the Gulf Stream and offshore
waters, where a Cautionary Statement will be issued. Otherwise,
seas 3-5 feet.
Saturday(previous)...Surface high pressure settles closer to the
Ohio Valley, keeping north winds around 15 knots through the day.
This will continue to produce less than favorable boating
conditions with choppy seas up to 5 feet offshore and in the Gulf
.PRELIMINARY POINT TEMPS/POPS...
DAB 33 52 41 62 / 0 0 10 10
MCO 35 56 40 64 / 0 0 0 10
MLB 35 58 45 64 / 0 0 20 30
VRB 37 61 47 66 / 0 10 20 30
LEE 32 55 39 63 / 0 0 0 10
SFB 33 55 40 63 / 0 0 10 10
ORL 35 56 42 64 / 0 0 10 10
FPR 36 61 44 66 / 0 10 20 30
FL...Freeze Warning from 3 AM to 8 AM EST Saturday for Coastal
Volusia County-Inland Volusia County-Northern Lake County-
Southern Lake County.
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1000 PM CST Fri Jan 5 2018
.SHORT TERM...(This evening through Saturday)
Issued at 207 PM CST Fri Jan 5 2018
Surface analysis this afternoon shows arctic high pressure
centered near KINL with the potent nor`easter having moved into
the Canadian maritimes and a wave quasi-stationary front extending
southeast from Alberta province through the TX/OK panhandles.
Aloft, the pattern of the deep NOAM trough east with a strong
western ridge continues, keeping the Upper Midwest within dry and
cold northwest flow. The center of the high will slide southeast
along the Mississippi River into the western Ohio Valley by
tomorrow morning then continue moving east tomorrow while the
aforementioned surface front slowly moves east as a warm front.
The main consequence of this scenario will be one more night of
frigid air across the area. However, winds will be just enough
over western and central MN such that they will create wind chills
into the -25F to -30F range late tonight through late Saturday
morning. As such, have opted to issue a Wind Chill Advisory. Even
where winds do go calm, just the slightest bit of wind can create
wind chills in the -15F to -25F range. Otherwise, clear skies will
prevail tonight thru tomorrow morning, resulting in good
radiational cooling with the lighter winds, producing lows
generally in the -10F to -20F range. As for tomorrow, being on the
backside of the high will allow winds to swing around to a warmer
southerly flow. Even with the increase in clouds ahead of the
incoming warm front, warm air advection will commence with highs
generally 10-20 degrees. A weak disturbance driving southeast
within the mean northwest flow will bring some light snow showers
to northern MN through the day on Saturday but the timing of it
should push it off to Saturday night.
.LONG TERM...(Saturday night through Friday)
Issued at 207 PM CST Fri Jan 5 2018
A noticeable transition will commence with the weather over much
of the CONUS, specifically due to changes in the upper level
pattern and the potential for a larger storm in the latter portion
of the next week.
The aforementioned weak upper level disturbance will continue to
drive southeast Saturday night, bringing flurries and light snow
showers for mainly northern and eastern portions of the coverage
area. At most, a tenth or two of snow accumulation may come from
this activity and such accumulations would be rather isolated.
After this minor event, the warm front will push through the area
Saturday night through Sunday, resulting in a very strong warm-up
for Sunday and this warmer air will remain in the area through
Wednesday. Not only will the surface warm font be at play but the
warmer ridge from the western CONUS will, in a weakened form,
shift east which will bring higher H5 heights and aid in
temperatures climbing to the lower to middle 30s Monday-Wednesday.
However, another strong pattern shift will take place Thursday
into Friday in large part due to a potent cutoff low moving
onshore the west coast on Tuesday. Both the ECMWF and GFS agree on
bringing this low across the Rockies and into the Central Plains
Wednesday night. This low is expected to aid in surface
cyclogenesis over CO/NE/OK Wednesday night. Both longer term
models also agree on bringing the system northeast toward the
Great Lakes through midday Thursday. However, there are still some
differences in track and its alignment with deeper moisture, along
with how much cold air the system can entrain within it from
Canada. So, while there is growing confidence on there being a
well-organized storm system which will impact the mid-and-upper
Mississippi River Valley, the details of the exact storm track and
other ingredients, which would then translate to its sensible
precipitation production, remain unclear.
Once this system moves through, there is fairly high confidence
that the week will end with another dose of very cold air,
dropping in from Canada, as the pattern of a deep trough east and
strong ridge west regains control.
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1000 PM CST Fri Jan 5 2018
No issues tonight with high pressure moving through. This high
slides off to the east Saturday and will be responsible for
strengthening southeast winds during the day. As the high slides
east, clouds currently stuck over the Dakotas will start working
east across the MPX area. We should see a narrow strip of 2k-5k ft
cigs work in with lead WAA, similar to what the HRRR shows, so
trended a few hours of a CIG in this range at the terminals based
more on the faster hrrr/nam timing. The 00z NAM and GFS are
trending drier Saturday evening for the MPX area, so feel good
going with a dry forecast for all terminals.
KMSP...latest models are trending drier for Saturday evening, so
feel even stronger about MSP remaining dry.
/OUTLOOK FOR KMSP/
Sun...MVFR cigs with IFR possible. Wind SW 5-10 kts bcmg W.
Mon...VFR. Wind W 5-10 kts.
Tue...VFR. Wind SE 5-10 kts.
MN...Wind Chill Advisory from 3 AM to 10 AM CST Saturday for
Area Forecast Discussion
National Weather Service Blacksburg VA
941 PM EST Fri Jan 5 2018
Strong Arctic high pressure will gradually build in from the
northwest through Saturday resulting in continued bitterly cold
temperatures and low wind chills. The center of the high should
pass overhead by the end of the weekend ahead of the next
complex area of low pressure that arrives by Monday. Weak high
pressure will follow this system with a return to somewhat
warmer weather by the middle of next week.
.NEAR TERM /THROUGH SATURDAY/...
As of 940 PM EST Friday...
No changes were made the location or time of the current wind
chill headlines. A weak upper level wave rotating through the
deep eastern U.S. trof has helped tighten the pressure gradient
and brought an increase to wind gusts in the mountains, as well
as cloud cover. A few bands of light snow have also developed
across the New River and Roanoke Valleys. Added small POPS to
this area and kept higher chance POPS across western Greenbrier
County where upslope flow is greatest.
01Z HRRR shows a slight uptick in low level winds early in the
overnight period before slightly weakening after 10Z, and
adjusted the wind grids and apparent temp grids accordingly.
These winds should help keep low temps slightly above records,
but if winds should decouple in the valleys for only a couple of
hours, records could be reached.
Pressure gradient should continue to weaken Saturday as the center
of the Arctic high slowly approaches from the northwest. However
still enough of a jet aloft to keep blustery conditions in place
despite increasing inversion levels. This will likely keep wind
chill headline criteria going through midday and perhaps longer over
the far west pending temps/winds Saturday morning. Otherwise should
see drier air and subsidence finally win out with sunny skies east
and return of more sunshine mountains during the afternoon if not
sooner. Highs again rather similar to today given little change in
850 mb temps which again support highs mostly teens mountains to
mid/upper 20s east.
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 300 PM EST Friday...
Main highlights in this period include:
- Moderating trend toward less unseasonably cold temperatures
Saturday night through Sunday.
- Light wintry mix to rain on cold pavement event Monday with
potential travel impact Monday.
Amplified mid-level trough associated with anomalously low 850 mb
temperatures with the Arctic air will progress eastward off the
coast Saturday night. In its wake, we`ll see a large dry surface
high pressure and initially zonal mid-level flow take hold.
Anticipate dry conditions Saturday night under high pressure along
with 850 mb temperatures running from -6 in the far southwest to -15
in the central VA Piedmont. Good radiational cooling however will
still lead to another cold night with lows in the single digits to
around 10 above, though without the even lower wind chills. Into
Sunday, initially sunny skies Sunday morning gives way to increased
mid and high clouds ahead of the next low pressure area coming out
of the Deep South. Continued warm advection and decreasing
insolation with time leads to highs within a couple degrees of
Into Sunday night, utilized a modified non-diurnal temperature curve
to show some cooling through the mid-level cloud deck to lowest
values in the 20s early, then begin to hover or slowly rise amid
low-level warm advection by a couple of degrees by daybreak Monday.
Regarding the wintry precip event for the Monday timeframe, today`s
12z NWP suite has shown less QPF than prior runs, as the southern
stream closed low aloft largely dives to our southwest Monday/Monday
night leading to less favorable westerly confluent mid-level flow.
Another source of uncertainty is on precipitation onset and what the
thermal structure is aloft and the related precipitation type. Air
mass below 700 mb to the surface is exceedingly dry per NAM/GFS
BUFKIT leading up to Monday morning. While warm nose temperatures
would support light ice pellets to freezing rain to rain, given the
unsaturated moisture profile, following a colder wet-bulb curve
aloft to the ground may be more appropriate at onset. Current
thinking is that light wet snow may initially begin in the western
Appalachians to the western Blue Ridge through mid-morning Monday,
starting later in the Piedmont. A west to east transition from snow
to freezing rain to cold rain is expected Monday by midday in the
far southwest VA/NC mountains and into the mid-afternoon hours
across the rest of the Blacksburg forecast area. It may take until
late afternoon if at all for wintry precip to fully erode in the
Greenbrier Valley into the Highlands. It`s important to keep in mind
though, that pavement temperatures are likely below freezing and
will likely remain that way through the event. So while air
temperatures may turn above freezing during the day, the
ground/pavement may not recover as rapidly. Even pure cold rain may
still yield slick road conditions given the pavement temperature
conditions. Rain then begins to transition back to light snow
showers in the western upslope areas late Monday night in the wake
of the system with decreasing PoPs. Would expect negligible snow
accumulation amounting to little more than a coating, with the
greater impact being from ice accretion with amounts supporting a
potential light glaze (a few hundreths to as much as 0.10"). Will
continue to highlight potential for wintry mix in the HWO, and it`s
quite possible a winter headline could be needed for this period
once precipitation type uncertainties can be better firmed up. Kept
high temperatures on the low side in the mid/upper 30s given
clouds/precip and some cooling wet-bulb effects, falling only into
the upper 20s to low 30s Monday night.
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 300 PM EST Friday...
Still should have some residual upslope rain/snow showers early
Tuesday in western locales but should end by the morning. The long-
awaited warm-up can then begin later Tuesday, finally returning to
above-normal values into the 40s to lower 50s with plentiful sun.
As surface high to the north slides offshore Tuesday night, wedge
conditions then begin to develop late Tuesday night into the
mid/late week timeframe. As easterly flow becomes enhanced along the
ridges would expect plenty of clouds and cooler, though still
appearing to be near/above normal temperatures. May see off-and-on
light showers but nothing overly impactful at this point.
Into Thursday and beyond, less predictability and solution
consistency then becomes apparent in the 12z NWP suite. This is due
to unsettled weather in the western US/Rockies that eventually
advances eastward. That doesn`t say much, though significant
differences in timing really do limit what may transpire in this
period. It does look quite active with temperatures trending on the
above-normal side of the ledger. Stuck mostly with a blend of
guidance to minimize forecast errors.
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
As of 629 PM EST Friday...
VFR conditions were noted at all TAF sites at 6 PM EST, with VFR
ceilings noted at KBLF and KLWB. As another weak upper level
disturbance moves through this evening, expect winds to increase
slightly and ceilings drop to MVFR levels at KBLF and KLWB after
06Z (1 AM EST).A few snow showers may form at these TAF sites
between 02Z-11Z, but visibilities will remain VFR.
East of the Blue Ridge (KROA/KLYH/KDAN), VFR conditions should
continue with any ceilings at KROA remaining at VFR levels. KBCB
will remain in between with mainly VFR under scattered/broken
low clouds although a brief period of MVFR could occur into
Gusty winds, especially in the mountains, will continue tonight,
and increase during the overnight hours with some gusts over
30kts possible at KROA. Winds will remain gusty Saturday, but
peak wind speeds will be slightly less (15-25 kts) that today.
Of note...the observation from KDAN is unavailable due to
a system processor failure. Will continue to provide a forecast
TAF since VFR and winds remain the only issue at this point.
Will likely be next week before observations resume once parts
arrive and can be put into operational mode at the site.
With surface high pressure moving overhead on Sunday will see
diminishing winds, a return to widespread VFR weather (even in
the mountains), and slowly moderating temperatures.
Arrival of a fast moving low pressure system may result in
another round of sub-VFR flight restrictions mainly west of the
Blue Ridge on Sunday night - spreading east across the Piedmont
on Monday. Widespread MVFR to IFR restrictions with a wintry mix
of precipitation gradually transitioning over to rain is
expected as the system moves northeast through the region on
Monday. Return to VFR across the region should occur on Tuesday
with perhaps only some lingering MVFR cigs across the mountains
early on. Weak wedge develops by Wednesday with possible sub-VFR
in low clouds across much of the region.
Antecedent conditions are dry. In spite of the cold, the
dryness of the current Arctic airmass and lack of meaningful
precipitation the last 30-60 days is beginning to set the stage
for potential fire concerns. Sun angle is low so the active burn
window is small, however with little or no moisture recovery at
night conditions are becoming favorable to sustain fire starts
if they occur. Ignition sources for this time of year given the
cold weather would most likely come from hot ashes being dumped
out by folks using wood stoves.
A continued series of Arctic air masses is expected during the
next couple of days, likely threatening record low maximum
temperatures and perhaps even record low minimum temperatures.
Here are the records into Saturday.
Climate Records Summary
Site MinT Year LoMax Year
KBLF -4 2014 14 1988
KDAN 10 1999 27 1999
KLYH 3 1924 18 1912
KROA 2 1924 18 1912
KRNK -2 2014 13 1959
As of 230 PM EST Friday...
The processor with the automated observing system at Danville
has failed. Thus no observations are being transmitted due to
this issue. There is no estimated time for power restoration as
will be next week before parts on order arrive.
Several stream and river gages have been reporting bad data, and
is due to ice affecting the gage. Most of these have been
deactivated on our web page. Given the dry conditions, the
threat of flooding is zero.
VA...Wind Chill Advisory until noon EST Saturday for VAZ007-009>019-
Wind Chill Warning until noon EST Saturday for VAZ020.
NC...Wind Chill Advisory until noon EST Saturday for NCZ001>006-
WV...Wind Chill Advisory until noon EST Saturday for WVZ042>044-507.
Wind Chill Warning until noon EST Saturday for WVZ508.