Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/14/23
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1006 PM EDT Mon Mar 13 2023
.UPDATE...
Issued at 1005 PM EDT MON MAR 13 2023
Low clouds with mainly just flurries or isolated light snow
showers are falling from the radar returns across the region. An
upstream disturbance is leading to more substantial and extensive
returns over southwestern OH, portions of IN and northern KY. This
activity should move across the region tonight accompanied by an
upslope wind component. Isolated to scattered snow showers or
flurries are anticipated and some light accumulations of a dusting
are possible on the ridges where snow showers are more prevalent
and for elevations above 1500 to 2000 feet in the southeast where
a few tenths of an inch could fall in some areas. Other than some
timing adjustments based on radar to pops, temperatures this
evening were lowered a few degrees on average to account for
recent observation trends.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 337 PM EDT MON MAR 13 2023
The afternoon surface analysis shows a trough pushing slowly
across eastern Kentucky. This has helped to generate rain/snow
showers through the afternoon mainly in the far SE, with even
some graupel reported at a few locations in heavier activity where
steeper low level lapse rates reside. Meanwhile, upstream we see
high pressure cresting across the Northern Plains and Upper
Mississippi River Valley. This will be a keep player in the
forecast for Tuesday night. Tonight, a mid and upper level low
will rotate toward the Mid-Atlantic States. The base of this
trough will swing into the Ohio Valley and could generate some
snow shower activity especially in the higher terrain in SE KY,
where favorable upslope flow will continue to develop. This shower
activity is noted on some of the synoptic models including the
ensembles, but also in the HRRR where you can see some weaker
shower activity indicated by the latest output. Given this did
keep a slight chance of snow showers mainly later tonight into
early Tuesday morning. This could lead to some light accumulations
(less than an inch)on mainly grassy surfaces outside of perhaps
Black Mountain and will mention this possibility in the HWO for
now given uncertainty remains.
The snow showers and flurries will wind down through the day
Tuesday, but could linger in the far east until later in the
afternoon given some steeper low level lapse rates noted. Outside
this high pressure will spread toward the Ohio Valley through the
day and skies will slowly clear from west to east. However,
overall diurnally limited day is expected under northwest flow
and cold air advection, with highs topping out in the upper 30s to
lower 40s. This high pressure will crest across eastern Kentucky
by Wednesday morning. The clearing skies and calm conditions will
settle across eastern Kentucky leading to some of the coldest air
we have seen since around February 23rd, with lows in the teens
in the valleys and around 20 degrees on the ridges. Given this did
lean toward the lowest NBM member values, but they may not be low
enough given the diurnally limited day and low dewpoints on
Tuesday afternoon. This will kill or severely impact any
vegetation that has developed or is exposed. This will continue to
be mentioned in the SPS that has been coordinated with KY AG and
surrounding offices.
.LONG TERM...(Wednesday through Monday)
Issued at 422 PM EDT MON MAR 13 2023
The extended portion of the forecast will be plagued by only one
system - but otherwise should be fairly tame, and cool. We will
start off Wednesday morning with surface high pressure centered
across the state, and an exiting trough aloft with building heights
from the west. The clear skies, in addition to increasing
subsidence, and lessoning northerly flow aloft, will allow for a
warm-up in temperatures throughout the day Wednesday (after a very
cold start), with highs generally around or just above 50 degrees.
Did make some adjustments to the overnight low Wednesday
night/Thursday morning - since continued subsidence, clear skies,
and light southerly winds, could bring a good set up for decoupling
in the deeper valleys, especially in the northeast.
Thursday will continue the warming trend, as the upper level ridging
pattern overhead begins to shift farther east, putting us more into
the SW flow side. The same is true for the surface high pressure
system, as it continues to exit east of the state, and allows return
flow to take hold of the state. This SW flow will also be the
precursor for an upper level trough and surface low pressure system
moving in from the west - helping to advect moisture in the form of
clouds into the region ahead of the approaching system.
As of 12Z Thursday, a strong upper level trough will be present
across much of the west-central United States, including the Rockies
and portions of the Great Plains. Meanwhile, an associated surface
low pressure system will be strengthening across the Great Plains.
This whole pattern will continue to shift eastward throughout the
day, with the surface low reaching the Mid/Upper Mississippi Valley
by 0Z Friday. As the system progresses eastward, it will continue to
not only gain strength, but advection from the Gulf will help it to
ramp up in moisture content as well. While there are still quite a
bit of differences in model agreement for the exact placement and
strength of the surface low, there is also very good agreement that
a second shortwave will develop along the eastern fringe of the
trough, and that will help to strengthen the system overall as well.
By 12Z Friday, the center of surface low pressure should be located
across the Great Lakes, dragging a potent cold front with it -
sweeping eastward across the Commonwealth late Thursday night and
into the first part of the day Friday. Given the vast amount of
moisture with this system, there is a good chance that pops could
begin intruding on the JKL CWA by Thursday night, increasing as the
front nears and moves over during the day Friday. Both the GFS and
ECMWF actually spare Kentucky somewhat, showing the highest QPF
swath across the Deep South - closer to the Gulf moisture, and
centered around a potentially secondary low pressure system that
develops along the front. Either way, expect likely pops through the
day Friday. Though with temperatures only topping out in the upper
50s to low 60s, still questionable how much instability we will
actually have here. Not expecting much in the way of thunder or
severe threat.
As quick as this system moves in, it will move back out and east of
the state. The cold front will be out of KY by late Friday, as the
surface low becomes more occluded to our north. Even after the
precip and cold front exit the state, the upper level trough will
still be in place across the Great Lakes Region, and will be
quite strong. Drier northerly flow will move back into place
across the region, but it will also be cold, with the source
region being northern Canada. Temperatures Saturday will top out
in the mid and upper 40s again - which is actually surprising
considering how strong the northerly push is aloft - figured it
might be a bit colder. Winds will also be quite breezy behind the
front, especially during the day Saturday, given the very tight
pressure gradients aloft, and good mixing taking hold. Did not
include any ridge/valley splits or decoupling at this time, as the
strength of the winds could play a role.
The trough will remain in place and continue advecting cooler air
into the region through the rest of the day Sunday as well, with
surface high pressure finally moving in from the NW from Sunday
night through Monday. Either way, conditions may be cool, but they
will be dry to finish out the period. Highs on Sunday will be in the
low to mid 40s still, warming slightly into the upper 40s and low
50s on Monday. Overnight temperatures from Saturday through Sunday
night will be below freezing pretty much everywhere, settling in the
low to mid 20s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 840 PM EDT MON MAR 13 2023
A mixture of MVFR and VFR was reported at issuance time. Mainly
VFR is expected to prevail for the first 3 to 5 hours of the
period, before an approaching disturbance and associated
isolated to scattered snow showers and flurries arrives. As that
system traverses the region mainly MVFR is anticipated across the
southeast and eventually the south for much of the 6Z to 15Z
period, before improvement to VFR in all areas. Winds will
generally be from the WNW to NW through the remainder of the
period at 5 to 10 KT through 12Z, before averaging northwest
around 10KT to end the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...DJ
LONG TERM...JMW
AVIATION...JP
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
958 PM CDT Mon Mar 13 2023
.UPDATE...
Issued at 958 PM CDT Mon Mar 13 2023
Going forecast is in generally good shape this evening, though did
make some tweaks to lower QPF/snow amounts slightly in northwest
IN. Regional radar mosaic depicts somewhat disorganized multi-band
lake effect showers affecting parts of northwest IN at mid-
evening. Web/plow cams across northern Lake and Porter counties
show little/no accumulation or significant impacts to visibility
at this time. Slightly better convergent focus appears to be
located further east into southwest MI/north central IN, though
CAM guidance does suggest this may slip back toward the
Porter/LaPorte county line later tonight. RAP soundings depict
equilibrium heights around 7500 ft will persist through midnight,
then gradually decrease as deep subsidence in the wake of the
departing upper trough leads to lowering inversion heights after
midnight. With generally no accumulation occurring so far, did
trim QPF/snow amounts across northwest IN, with amounts of a trace
to around a half inch expected.
Elsewhere, flurries and light snow showers continue at this hour,
but these will also diminish as subsidence strengthens and begins
to erode from the north. Otherwise, temp and wind trends look good
through the rest of the night.
Ratzer
&&
.SHORT TERM...
Issued at 300 PM CDT Mon Mar 13 2023
Through Tuesday night...
Blustery northerly winds will continue today in the wake if this
mornings cold frontal passage, but speeds are expected to abate
into this evening. The presence of steep low-level lapse rates in
this cold air advective regime will also continue to support a
deck of strato cu with intermittent periods of snow showers and
flurries into early this evening. However, the most pronounced
snow showers are expected to be confined to far eastern IL and
especially into northwestern IN, where improving lake effect
parameters this afternoon and evening will support more
organized snow showers.
Far northwestern IN looks to be under streaming lake effect snow
showers tonight, with the primary focus likely shifting over
Porter county IN later this evening and overnight. Lake induced
equilibrium levels peaking near 8,000 ft tonight should be
sufficiently high enough to bisect through the DGZ as 850 to
surface water temperature differences peak around 15C.
Accordingly, snow rates with these streaming snow showers
could become of moderate intensity at times tonight. While this
may end up resulting in some localized travel impacts across
parts of Porter county IN tonight due to accumulating snow, it
appears the residence time of the snow showers will be somewhat
limited as the better focus gradually sets up east of the area
late tonight. For this reason, it appears some localized amounts
of 1 to perhaps as high as 3" could occur tonight into parts of
Porter county IN. We will continue to message this in our weather
story products.
Outside of the lake effect snow for parts of northwestern IN
there remains some uncertainty as to how quickly things will clear
our tonight as low-level moisture potentially remains trapped
under a subsidence inversion aloft for several more hours. While
satellite trends continue to show holes within the upstream
strato cu deck streaming southward across WI, this deck remains
rather expansive. For this reason, we may be slow to see a total
clearing of the cloud cover tonight. This could ultimately have
some impact on how cold temperatures get overnight. However,
with the potential to see more holes develop through the night I
did not want to make any big changes to temperatures at this
point. We are therefore still expecting lows to fall into the
teens over far northern IL and into the low to mid 20s south.
A surface ridge of high pressure will shift across the area
Tuesday afternoon. Light winds and mainly sunny skies should
result under this high Tuesday afternoon, though temperatures
will remain chilly with highs remaining in the 30s. Thereafter,
another chilly night is likely Tuesday night, but conditions will
begin to warm with a return to southerly flow for Wednesday.
KJB
&&
.LONG TERM...
Issued at 300 PM CDT Mon Mar 13 2023
Wednesday through Monday...
Key Messages:
* Strong weather system to move through the region late week
bringing widespread rain showers Thursday ending with snow
showers/flurries Friday into Saturday
* Strong winds may accompany Thursday-Friday system with gusts
over 40 mph possible, best chances behind cold front on Friday
* Temperature roller coaster continues with highs near 50 mid
week, 30s for the weekend, then 40s early next week
Surface high pressure responsible for a quiet Tuesday will shift
east by Wednesday allowing warm air advection to take hold across
the region aided by lee cyclogenesis east of the Rockies.
Lingering snowpack will limit initial warming on Wednesday,
especially north, though still think mid 40s are attainable there,
with upper 40s to lower 50s expected across the rest of the area.
Aloft the upper jet pattern remains split with a pair of upper
waves traversing the flow across the northern and southern
Rockies. The interaction between these waves and any potential
phasing will play a role in the details for our late week system
which is expected to bring widespread rain showers to the region,
potentially ending with snow showers as the resultant closed upper
low slowly exits the Great Lakes region. Ensemble guidance is in
fairly good agreement with the general placement and evolution of
the surface low, though they vary slightly on the placement and
strength, with the GEFS having a slightly further south and deeper
low compared to the ECMWF Ensembles. In general though, a
sub-1000mb low appears likely with a track somewhere across
northern Illinois/southern Wisconsin. Warm and moist air is
forecast to lift north from the gulf with anomalously high PWATS
feeding over the region. There is a signal in the ensembles that
an axis of lower QPF may focus into at least parts of the local
area limiting QPF amounts some, potentially due to a combination
of convection across the lower Mississippi Valley cutting off
moisture north along with influence of the dry slot. Nevertheless
it looks like localized downpours are likely at times as showers
lift across the area.
Depending on how deep the surface low strengthens and where
exactly it tracks, winds could become quite gusty, especially with
a stronger system. Accordingly, wind gusts in excess of 40mph are
becoming more probable, potentially out of the southwest in the
warm sector Thursday, and more likely in the wake of the cold
frontal passage with northwest winds on Friday.
Gusty winds persisting Friday night into Saturday combined with
temperatures dropping into the lower 20s will will lead to wind
chills in the single digits by Saturday morning and teens through
the daytime hours. Be sure to bundle up this weekend! Temperatures
then very gradually moderate heading into early next week with
mid-upper 30s for highs on Sunday and lower to mid 40s Monday.
Petr
&&
.AVIATION...
For the 00Z TAFs...
- Light snow showers possible through this evening.
- Winds continue to be breezy from the NNW, will diminish gusts
overnight, before winds decrease Tuesday afternoon.
- VFR ceilings take hold, and continue lifting overnight to
clearing skies Tuesday.
Light snow showers will continue through the evening, as
additional moisture filters through the southern Great Lakes. Once
these end, 02-03z, expect dry conditions to prevail throughout
the remainder of the period.
Breezy nnw winds continue to flow across the region, with gusts
in excess of 20-22kts possible for the next few hours, before
gusts begin to diminish overnight. Winds remain nnw/nw overnight
into Tuesday morning ahead of High pressure that will drift
overhead Tuesday afternoon and evening. Some short range models
hint at a weak lake breeze sliding across the southern terminals
Tuesday afternoon, however not enough confidence in distance to
include at ORD due to weak nature and timing of High arrival.
Ceilings are expected to remain VFR across much of the region,
with MVFR ceilings continuing at GYY as nnw winds usher
additional moisture off the lake. Ceilings lift and clear tonight
into Tuesday, as High pressure begins to invade the region.
Baker
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...IN nearshore waters until 9 PM Tuesday.
Small Craft Advisory...IL nearshore waters until 10 AM Tuesday.
&&
$$
Visit us at weather.gov/chicago
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSChicago
www.twitter.com/NWSChicago
www.youtube.com/NWSChicago
Area Forecast Discussion
National Weather Service Mount Holly NJ
901 PM EDT Mon Mar 13 2023
.SYNOPSIS...
A coastal storm will move northeast offshore of the Mid Atlantic and
northeast states tonight through Wednesday. This low will drift out
to sea Thursday as high pressure builds to our south. A cold front
will move across the area Friday into Friday night, before moving
out to sea Saturday. High pressure will build into the region Monday.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
Made some changes to the forecast heading into tonight and
tomorrow with respect to snow amounts, resulting in a downgrade
of Winter Storm Warnings to Winter Weather Advisories in Morris
and Warren Counties. Even there, the advisory-level amounts look
like they will be limited to higher elevations in northwestern
portions of those counties. The axis of precipitation
associated with coastal low pressure intensifying offshore will
continue to lift northward as the storm tracks to near Cape Cod
Tuesday morning. While earlier model runs hung some of this
precipitation farther south and west into our region, the
latest guidance now lifts most of the steadier rain and snow
north of our region overnight. The latest radar as of 9 PM lends
support to these model trends, with diminishing returns to the
south and west. If the latest HRRR is right, even portions of
the Poconos and Sussex County NJ will see precipitation taper
off for awhile overnight. Additionally, the only places that are
seeing snow are above at least 1200 or 1500 ft elevation at the
moment. While colder air advection and some stronger forcing as
the storm intensifies should aid in changing rain to snow at
lower elevations overnight into Tuesday morning, precipitation
amounts look much more limited than earlier expectations. There
is still model support for some wraparound precipitation as the
mid and upper- low shifts offshore later Tuesday morning
through the afternoon, and that will be when lower elevations
including down to the I-95 corridor will have their best shot at
some snow. However, amounts look light, especially from I-78
southward, and will struggle to accumulate, especially on
pavement, during the daytime hours.
Wind advisory continues in effect for the southern half of the
CWA on Tuesday and Tuesday night. The pressure gradient behind
the storm will create gusts of around 45 mph at times during the
late morning and afternoon Tue. It`s possible that more areas
may be added with future forecasts.
Lows tonight will be in the upper 20s to low 30s for our area with
some mid 20s for the Poconos. Highs Tue will be in the low 30s N/W
and in the upper 30/low 40s for most other areas. Some mid 40s are
possible for southern Delaware.
For Tuesday night, light wet snow across the northern areas
will end quickly by the evening and gusty winds will continue
over the area. Lows will be in the 20s for NE PA and northern NJ
while mins in the low 30s will be across Delmarva, metro
Philadelphia and south NJ. Wind chills about 10 degrees colder
than the lows are expected.
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
The coastal low will remain offshore of the Gulf of Alaska
Wednesday, before drifting out to seas Wednesday night through
Thursday. Meanwhile, high pressure will build across the central
Appalachians Wednesday and into the southeastern states
Wednesday night into Thursday. This will create a strong
pressure gradient Wednesday, before it begins to weaken some
overnight into Thursday. Strong, gusty winds will continue into
the day Wednesday with gusts 30-40 mph possible during the day,
before diminishing overnight. Dry conditions will be in place
Wednesday through Thursday night, before the next system
approaches the area.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
On Friday, an area of low pressure will move across the Great
Lakes region, with a cold front approaching the Mid Atlantic
region. This cold front will move across the area Friday night,
while a secondary low develops near the area, before it moves
northeast along the front Saturday. This front will move out to
sea later on Saturday. Rainfall is expected to move into the
area during the day Friday and continue at times Friday night
into Saturday, before ending by Saturday night.
High pressure builds well to our west Sunday while low pressure will
be in place across eastern Canada. This will keep a tight pressure
gradient across the area, leading to gusty winds on Sunday. Wind
gusts of 20-30 mph will be possible. The high will continue to build
eastward across the Mid Atlantic region during the day Monday,
allowing winds to diminish. Dry weather is expected for Sunday
through Monday.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
AVIATION /19Z MONDAY THROUGH SATURDAY/... The following discussion
is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and
surrounding areas.
Tonight (through 12Z)...Lingering IFR ceilings at KMIV/KACY should
lift in the next hour or two as precipitation moves north. Periods
of rain will continue through about 03Z-05Z across the remaining
terminals before tapering off (with the exception of KABE where
precip may linger and changeover to snow showers by morning).
Ceilings should lift to MVFR for all terminals overnight, with
potentially even some VFR for KPHL/KILG/KMIV/KACY late. W-NW winds
of 10-20kts will becoming increasingly gusty through the night with
gusts up to 25-30kts. Low-Medium confidence regarding ceilings
across the area.
Tuesday...Some wrap-around moisture with departing coastal low will
persist through the day. Chance for some snow showers at KABE with a
mixture of rain/snow showers at KRDG/KTTN/KPNE/KPHL. For
KMIV/KACY/KILG, there is a chance for some rain showers, but
predominantly will remain dry. Ceilings will generally be VFR with
potentially some MVFR in some heavier showers. Winds remain elevated
out of the W-NW at 20-30kts with gusts up to 40kts. Medium
confidence.
Tuesday night...VFR with decreasing clouds from south to north. W-NW
winds of 15-20kts with gusts up to 30-35kts.
Outlook...
Wednesday-Wednesday night...VFR conditions expected. Northwest winds
10-15 knots with gusts 20-30 knots during the day, diminishing to 5-
10 knots overnight.
Thursday-Thursday night...VFR conditions expected with increasing
clouds overnight. West winds 5-10 knots with gusts around 15 knots
during the day, becoming southwest around 5 knots overnight.
Friday-Saturday...Generally VFR, with periods of MVFR possible along
with showers likely at times. Southwest 5-10 knots during the day
Friday, becoming west to northwest Friday night, then west Saturday.
&&
.MARINE...
Low pressure strengthens while moving east of our waters tonight.
This strong system will remain just south of New England much of
Tuesday and into Tuesday night. Winds will ramp up this evening with
Gale flags set to go in place overnight. A few Storm force gusts are
possible later Tue into Tue night. Rain tonight and Tuesday. Rough
seas developing.
Outlook...
Wednesday...Gale Warning in effect through Wednesday.
Wednesday night...Small Craft Advisory conditions likely.
Thursday-Thursday night...Small Craft Advisory conditions possible
early, diminishing during the day.
Friday-Saturday...Small Craft Advisory conditions develop during the
day Friday and continue through Saturday.
&&
.TIDES/COASTAL FLOODING...
We will continue with a Coastal Flood Advisory for Ocean County
NJ since there continues to be an accumulation of water in
Barnegat Bay. The last few tide cycles have shown the tidal
gages varying within the Minor tide levels. Once the winds turn
NW/W on Tuesday, the water should decrease back to sub-advisory
levels.
Elsewhere, tides are expected to remain below advisory levels.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Wind Advisory from 1 PM Tuesday to midnight EDT Tuesday night
for PAZ060-070-071-101>106.
Winter Storm Warning until 6 PM EDT Tuesday for PAZ054-055.
NJ...Wind Advisory from 1 PM Tuesday to midnight EDT Tuesday night
for NJZ013>027.
Winter Storm Warning until 6 PM EDT Tuesday for NJZ001.
Winter Weather Advisory until 6 PM EDT Tuesday for NJZ007-008.
Coastal Flood Advisory until 6 AM EDT Tuesday for NJZ020-026.
DE...Wind Advisory from 1 PM Tuesday to midnight EDT Tuesday night
for DEZ001>004.
MD...Wind Advisory from 1 PM Tuesday to midnight EDT Tuesday night
for MDZ012-015-019-020.
MARINE...Gale Warning from 4 AM Tuesday to 6 PM EDT Wednesday for
ANZ430-431-454-455.
Small Craft Advisory until 6 AM EDT Tuesday for ANZ450>453.
Gale Warning from 6 AM Tuesday to 6 PM EDT Wednesday for
ANZ450>453.
Small Craft Advisory until 4 AM EDT Tuesday for ANZ454-455.
&&
$$
SYNOPSIS...OHara
NEAR TERM...Dodd/OHara
SHORT TERM...Robertson
LONG TERM...Robertson
AVIATION...Hoeflich/OHara
MARINE...OHara/Robertson
TIDES/COASTAL FLOODING...O`Hara