Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/04/18
Area Forecast Discussion
National Weather Service Hastings NE
605 PM CST Wed Jan 3 2018
Issued at 559 PM CST Wed Jan 3 2018
Forecast models are hitting the fog pretty hard with the 15Z SREF
showing up to around 75 percent of its members with 1 mile or less
visibility in spots tonight. The 21Z RAP and 22Z HRRR are also
indicating fog with less than 1 mile visibility should develop
later tonight across many of our Nebraska counties. Therefore,
will expand mention of fog in our overnight forecast further east
and increase expected coverage and visibility reductions. Am also
going to add mention of fog to our Hazardous Weather Outlook.
.SHORT TERM...(This evening through Thursday)
Issued at 324 PM CST Wed Jan 3 2018
Satellite and observations continue to show a fairly narrow band of
stratus through the eastern part of the forecast area. In the west,
there are some higher clouds that are moving into the area.
There are a couple of questions for tonight. Several of the models
show that the current band of clouds will dissipate, but should
return as the sun goes down this evening. Have kept some clouds
around during the remainder of the afternoon and into the evening,
but expect that the clouds will be a little higher in the west. As
the lower clouds that are to the north move back into the area later
tonight there could be some fog developing along the clearing line.
There are some concerns with the fog. The higher clouds across the
west could make it a little harder to get some fog, but the
temperatures will still drop off and the temperature/dew point
spread becomes very small. Since the complete extent of the lower
clouds is a bit uncertain, have kept fog across the western part of
the forecast area.
The clouds should start to clear out of the area during the morning
on Thursday. With the sunshine and a little warm advection,
temperatures should be a little warmer for Thursday.
.LONG TERM...(Thursday night through Wednesday)
Issued at 324 PM CST Wed Jan 3 2018
Northwest flow continues Thursday night through Saturday. There will
be a cold front Thursday night with another push of colder air for
Friday, but temperatures should remain around the same as Thursday
for much of the area. By Saturday, warm advection kicks in again,
there should be sunshine and with south winds increasing during the
day, the temperatures should rise closer to near normal temperatures.
They will still be a little below, but it will be the first day
near freezing in nearly two weeks, at least for some locations.
Saturday night into Sunday night there will be an upper level wave
that moves through, as well as a cold front. Models have a few
differences in timing and strength of the system. This has caused
there to be some concern for what will happen. At this time, expect
there to be some precipitation from late Saturday night through
Sunday evening, somewhere around the area. Another concern will be
the precipitation type. There will be warmer temperatures during the
day and there could be a change to rain.
Monday through Wednesday will be another dry period. There will be
northwest flow across the area and with that some temperature
changes, but Monday and Tuesday should be warmer days with a cool
down for Wednesday.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 559 PM CST Wed Jan 3 2018
See update section above regarding fog concerns for tonight. Have
certainly decreased visibilities in the TAFs with this update and
may need to go lower at KGRI if this fog pans out. Will need to
watch out for low clouds and fog tonight through at least mid
morning tomorrow and if fog does form it could take longer to burn
off then currently projected.
Area Forecast Discussion
National Weather Service Mount Holly NJ
933 PM EST Wed Jan 3 2018
Low pressure rapidly intensifies as it quickly moves northward to
the Atlantic waters east of New Jersey Thursday morning, then to the
Canadian Maritimes by Friday. Arctic high pressure will then build
into the East through most of the weekend. Low pressure is forecast
to track near our area early next week.
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
* Major winter storm to impact the region later tonight and
No major changes with the 930 PM update. Snow is beginning to
move into our area and banded structure is already developing
upstream. As a result, the going forecast looks on track. There
remain some differences between the high resolution models as
the HRRR depicts most of the mesoscale banding off shore, while
most of the other models depict banding, especially east of the
I 95 corridor.
Otherwise, bend of LAV/MET/MAV guidance was used with
temperatures. Pops increase from southwest to northeast tonight,
hitting on a thermal gradient providing lift just offshore for
precipitation formation. Snow will be widespread by the morning
commute. Mesoanalysis and more general details below...
A high impact winter storm is still expected to track up the east
coast tonight and Thursday. The first issue is the actual formation
of this low. Model data has struggled for the past several days
regarding how the storm forms with competing low centers.
Modeling has shifted to a more western center closer to the main
temperature gradient. A look at SPC mesoanalysis currently shows the
western low being more dominant. With this being said, the location
of convection will still be an issue as we draw closer to the event.
The further offshore convection fires the less moisture moves into
our region. As a result, the trend has been more precipitation
showing up with the afternoon model data given tendencies to the
western low. On the flip side, a concern still remains that dry air
on the backside of the storm could still lower QPF totals from the
The low pressure system will organize overnight and spread snow
northwest into our region. The 12Z 1/3 NAM soundings are near
freezing a few thousand feet up near the coast so some sleet could
mix in at times tonight.
Snow within the bands does have the potential to be moderate or
heavy at times with mesoscale models keying on this. Thus, large
differences in totals over short ranges could occur. Winds will
increase as well with bufkit soundings yielding gusts from 30-50 mph
in spots. Blowing and drifting of snow are major concerns.
General storm highlights:
Timing: Overnight and Thursday.
1. Blowing and drifting snow will occur regionwide. This will reduce
visibilities and make travel very difficult. The wind may result in
downed trees and power outages as well. The impacts will be rather
high from the blowing and drifting!
2. Snow totals look to range from a couple of inches in the Southern
Poconos up to ten inches at the shore. The Thursday morning commute
will be very difficult with the snow, blowing snow and cold.
3. Based on the increased totals, we expanded the warning further
northwest into Philadelphia and Trenton. An advisory was issued
further north and west. Although some locations may not reach the 2-
3 inch criteria, impacts such as blowing snow and timing with the
morning rush were taken into account.
4. A blizzard warning was issued along the coast given higher winds
5. Try to get any needed travel done this evening if possible.
While the advisories/warnings start this evening it may not be
until late evening or overnight before snow starts.
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
The storm will be the main show. Temperatures were a blend of
MET/MAV and generally in the 20`s. Pops are categorical across the
board, slightly lower in the Southern Poconos given the concern over
dry air on the backside of the storm. Snow should end from southwest
to northeast in the afternoon.
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Summary...Dangerous cold in the wake of the Nor`easter through at
least the first half of the weekend; a warm-up early next week as
low pressure tracks near our area.
Synoptic Overview...A deep upper-level trough in the East weakens
and shifts offshore Saturday night and Sunday. The flow then backs
ahead of the next trough sliding across the Midwest to the Southern
Plains. This combined with a return flow on the backside of
departing cold high pressure will allow the arctic air to start
eroding. Warming takes place early next week as a low pressure
system tracks near our area, however a more southern track may keep
colder low-level air in longer especially north and west of I-95.
For Thursday night through Sunday...Intense low pressure will be
moving into the Canadian Maritimes Thursday night into Friday. This
time frame will be dominated by arctic air and dangerous cold. Some
moderation is expected Sunday though as the major upper-level trough
lifts out. Until then, gusty northwesterly winds will combine with
very cold air temperatures leading to dangerously low wind chills
across the entire area. The gusty winds may continue blowing and
drifting snow into Friday. There is a Wind Chill Watch for the
southern Poconos for Thursday night into Friday. Some areas in this
region are forecast to experience wind chills right around -25F at
times. For now, we will keep the Watch going. Elsewhere, a Wind
Chill Advisory looks to be needed for Thursday night and Friday
morning with wind chills down around -10F. Additional Wind Chill
Advisories will probably be needed for Friday night and Saturday
night. The extent of this will depend on how much the winds stay up,
although it will be so cold just light winds will have an impact on
the wind chill. Overall, a very very cold time frame followed by
some improvement on Sunday as the arctic high starts to shift
For Monday through Wednesday...As the flow initially backs ahead of
the next system, warm air advection occurs as high pressure is to
our east. Low pressure is forecast to track near our area with a
cold front moving through Monday night. Some guidance however is
farther south with the primary surface low development, and if this
occurs the warming would be slowed especially in the low levels.
This could result in a period of some mixed/icy precipitation to
then even some rain as enough warming should take place. More
specifics as we get closer. It then look to turn colder for
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Rest of this afternoon...VFR with an increase in clouds at or above
15,000 feet. Light and variable winds overall.
Tonight...VFR through the evening for most terminals. Snow develops
generally in the 03-09z timeframe with earlier onset mainly at ACY
and MIV. The ceilings will lower to MVFR with visibilities dropping
to MVFR/IFR. Lower confidence with the onset of snow and lower
conditions, especially farther inland. Northerly winds around 5
knots, increasing late to 10-15 knots.
Thursday...Snow with IFR conditions (LIFR at times within heavier
snow where hourly rates could be 1-2 inches) to nearly all
terminals. The snow will end from southwest to northeast during the
afternoon. North to northwest winds increase to 15-25 knots with
gusts 30-40 knots resulting in considerable blowing and drifting
snow. The ceilings/visibilities should improve by later in the
afternoon. Moderate confidence.
Thursday night through Saturday...VFR with northwest
winds 10-20 knots with gusts 25-35 knots. The winds are expected to
diminish some Friday night into Saturday. Moderate to high
Sunday...VFR with west to southwest winds less than 10 knots. High
Monday...MVFR conditions possible with a chance for some mixed
precipitation or rain. Southwesterly winds 5-10 knots. Low to
Seas will gradually build tonight and continue well above five feet
through Thursday. We are still anticipating gales on both the bay
and ocean waters. Storm conditions are possible as well near buoy
44099. No changes to marine headlines as conditions gradually
deteriorate tonight. Precipitation may be mixed with sleet and rain
Thursday night through Saturday...Gale conditions through the
period, with at least moderate freezing spray (especially near the
coast) Thursday night and Friday and a good chance of heavy freezing
spray Friday night and Saturday. Gale warnings will be needed after
the Storm Warning expires for the Atlantic Delaware waters and is
already in effect for Delaware Bay and the New Jersey coastal waters
through Friday night. Low end gales may occur for a time Saturday. A
Freezing Spray Advisory is in effect Thursday night and Friday, and
a Heavy Freezing Spray Watch is in effect Friday night and Saturday.
There is high confidence in gales through at least late Friday and
in freezing spray being an increasingly hazardous threat.
Saturday night...Small craft advisory conditions are forecast, with
light to moderate freezing spray.
Sunday and Monday...Sub-advisory conditions area anticipated.
With the rapidly deepening cyclone off the coast and the full moon
having recently occurred, coastal flooding has become more of a
concern for the Thursday morning high tide. Reports from the
Manasquan area earlier today indicated water reaching portions
of low-water crossings and subsequently freezing. Though minor
flooding was not indicated at any of the official forecast
gauges this morning, the levels will increase with Thursday
morning`s high tide as the low moves into the Mid-Atlantic
The forecasts at tidal gauges along the New Jersey and Delaware
coasts have increased the past couple of days, as well. This
morning`s forecasts show fairly widespread marginal flooding at
gauges from Sandy Hook to Lewes with some potential up portions of
Given these trends, forecast ambient temperatures, and current water
temperatures along the coast, a Coastal Flood Advisory was issued
for the NJ/DE coast around Thursday morning`s high tide. Stagnant
water at high tide has the potential to freeze, creating an additional
impact to the potential for flooding.
Arctic cold will continue its hold on the region through Monday
morning with what we think will be increasing adverse impact on the
infrastructure as one of the most persistent cold outbreaks in
recent memory extends through Sunday January 7.
Additional record lows and record cold maximum temperatures should
be set Friday, Saturday and Sunday. The following list includes
records that may fall.
Record Low Temps for Friday 1/5: also Record low Max
Allentown (ABE).....not likely 15F (1968)
Reading (RDG).......not likely 12F (1904)
Atlantic City (ACY).not likely 18F (1968)
Philadelphia (PHL)..not likely 14F (1904)
Wilmington (ILG)....not likely 16F (1904)
Trenton (TTN).......not likely no rer avbl
Georgetown (GED)....9F (1958) no rer avbl
Mount Pocono (MPO)..not likely no rer avbl
Record Low Temps for Saturday 1/6: also Record low Max
Allentown (ABE).......not likely 13F (1942)
Reading (RDG).........not likely 15F (1912)
Atlantic City (ACY)...4F (1981) 17F (1912)
Philadelphia (PHL)...4F (1896) 18F (1942)
Wilmington (ILG)...7F (1924 and 1946) 20F (1988)
Trenton (TTN)...5F (1896 and 1904) no rer avbl
Georgetown (GED)...6F (1969) no rer avbl
Mount Pocono (MPO).....not likely no rer avbl
Record Low Temperatures for Sunday 1/7:
Allentown (ABE)....-4F (1942)
Atlantic City (ACY).4F (1884)
Philadelphia (PHL)..4F (2014)
Wilmington (ILG)....3F (2014)
Reading (RDG).......0F (2014)
Trenton (TTN).......2F (2014)
Georgetown (GED)....8F (2014)
Mount Pocono (MPO)..-8F (2014)
On the consecutive day below freezing watch: PHL had a high of
33 degrees on Wednesday, ending their consecutive days at or
below freezing at 7 days. This is tied for the 30th longest
stretch of below freezing days. The rest of our climate sites
are still on track to continue the stretch of below freezing
through at least Sunday.
PA...Winter Weather Advisory until 7 PM EST Thursday for PAZ054-055-
Winter Storm Warning until 7 PM EST Thursday for PAZ070-071-
Wind Chill Watch from Thursday evening through Saturday
afternoon for PAZ054-055.
NJ...Winter Weather Advisory until 7 PM EST Thursday for NJZ001-
Winter Storm Warning until 7 PM EST Thursday for NJZ012-
Coastal Flood Advisory from 8 AM to 2 PM EST Thursday for
Blizzard Warning until 7 PM EST Thursday for NJZ013-014-020-
DE...Coastal Flood Advisory from 8 AM to 2 PM EST Thursday for
Blizzard Warning until 7 PM EST Thursday for DEZ003-004.
Winter Storm Warning until 5 PM EST Thursday for DEZ001-002.
MD...Winter Weather Advisory until 7 PM EST Thursday for MDZ008.
Winter Storm Warning until 5 PM EST Thursday for MDZ012-015-
MARINE...Freezing Spray Advisory from 6 PM Thursday to 6 PM EST Friday
Gale Warning until 5 AM EST Saturday for ANZ430-431-450>453.
Storm Warning from 6 AM to 3 PM EST Thursday for ANZ454-455.
Area Forecast Discussion
National Weather Service Tucson AZ
250 PM MST Wed Jan 3 2018
.SYNOPSIS...A weak disturbance will pass through Southern
Arizona bringing a few sprinkles or light showers to the area late
tonight into Thursday. Dry conditions will then prevail Friday into
Saturday. A few showers may develop north of Tucson Saturday night
and Sunday. Unseasonably warm daytime temperatures will also
continue into next week. A stronger storm system may affect the
region by the middle of next week.
.DISCUSSION...Scattered to broken clouds were noted on satellite
imagery this afternoon across much of Southeast Arizona. Though the
area is currently under the influence of an upper ridge, conditions
will change in the coming hours as a shortwave trough approaches
from the southwest. Model solutions over the last 24 hours have
continued to trend upward with regard to PoPs, especially from
Tucson southward and eastward tonight into Thursday. Several hi-res
models including the HRRR and both U of A WRFs show an area of
showers pushing through the region from southwest to northeast late
this evening into early Thursday morning. A few showers may linger
through the day Thursday, but the trough axis and any associated
precip should be clear of the area by Thursday evening. Any
accumulations over the next 24 hours will be very light, generally a
trace to only a few hundredths of an inch at best.
We`ll dry out under ridging for Friday and Saturday with a few
passing high clouds. Upper level flow will flatten out late Saturday
into Sunday with a trough breezing quickly through the four corners.
We may see a few showers across the White Mountains Saturday night
as this happens, but nothing significant. More ridging builds in for
Sunday and Monday, with a weak wobble in the flow potentially firing
off some showers for the Whites again on Tuesday. The forecast could
then get a lot more interesting, as medium range models are
currently advertising a strong area of low pressure to move through
the state next Wednesday or Thursday. The preliminary PoPs inherited
from the midnight shift were increased slightly for days 7 and 8,
though it is likely the forecast will morph several times over the
next week as the details get clearer.
Daytime temperatures this week will continue to run on the warmer
side, generally from 6 to 12 degrees above average.
.AVIATION...Valid thru 05/00Z.
Cloud bases will continue to lower this evening allowing for SCT-BKN
clouds around 10-15k ft AGL. Expect BKN-OVC skies as low as 5-8k ft
AGL after midnight as a weak weather system moves in. Some virga and
-SHRA will be possible tonight and into Thursday morning mainly
south and east of KTUS. Gusty SFC winds will diminish this evening
and become terrain driven at less than 12 kts. Aviation discussion
not updated for TAF amendments.
.FIRE WEATHER...Dry conditions will prevail this evening before a
weak weather system passes through tonight into Thursday morning
creating a slight chance of showers mainly south and east of Tucson.
Winds will remain gusty through this evening before decreasing to
less than 10-15 mph and becoming terrain driven. Drier air will
return through Saturday before another chance of showers arrives
Saturday night into Sunday across the White Mountains.
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson