Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/24/19
AREA FORECAST DISCUSSION
National Weather Service Albany NY
941 PM EST Sat Feb 23 2019
.SYNOPSIS...
A complex storm system will approach the region from the
western Great Lakes Region and the Mid Atlantic states tonight
initially bringing a wintry mix of precipitation. A secondary
low pressure system near the New Jersey Coast moves toward New
England in the late morning into the afternoon, as the
precipitation will change to rain, as temperatures briefly warm
up. A powerful storm system will be moving across southeastern
Canada Sunday night, as a strong cold front moves across the
region with scattered snow showers, colder temperatures and
extremely windy conditions. Strong to damaging winds will
continue through Monday with some lake effect snow northwest of
the Capital Region.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A Winter Weather Advisory in effect through 7 am EST Sunday for
the western Adirondacks, Mohawk Valley, Taconics, eastern
Catskills, Schoharie Valley, the mid Hudson Valley, Greater
Capital District, and the Helderbergs of eastern New York, the
southern Berkshires of western Massachusetts, and the Litchfield
Hills of northwestern Connecticut...
A Winter Weather Advisory in effect through 10 am EST for the
southern Adirondacks and Lake George Saratoga Region in eastern
New York, the northern Berkshires in western Massachusetts, and
southern Vermont...
As of 941 PM EST...Precipitation not reaching the ground yet
across most of the region, except for over parts of Catskills
Mountains. NYS Mesonet observation indicating 0.01 precip near
western Ulster/Delaware county border. 00Z KALY sounding still
revealed a significant dry layer in the lowest 12,000 ft. It
will still take at least another few hours for precip to reach
the ground in valley locations around the Capital District, and
after midnight farther north. Latest hi-res guidance including
the HRRR and NAMNest indicating light frozen precip through much
of the overnight hours. No changes to current headlines or
snow/ice grids at this time.
A very active next couple of days is expected across eastern NY
and western New England. The first weather hazard to be dealt
with is another bout of light wintry mixed pcpn. High pressure
continues to shift east towards Nova Scotia tonight. The flat
mid-level ridging moves downstream, as a short-wave in the
southwest flow aloft and sfc trough will approach the region.
Isentropic lift increases on the 290K sfc for initially a very
brief period of light snow/sleet quickly changing to freezing
rain or rain, especially between 03Z-07Z. Locations north and
east of the Capital Region will likely have the greatest threat
of an extended period of sleet/freezing rain. Due to wet
bulbing, we were concerned a brief period of icing could occur
in Dutchess and southern Litchfield Counties, so we added them
to advisory. It will take a little time for the column to
saturate.
The low-level ageostrophic flow remains from the north to
northeast overnight, which will likely keep the sfcs coldest
again from Albany north/northeast. We believe the coverage of
the pcpn should rapidly increase from 06Z-11Z, as a secondary
low pressure system associated with a warm or occluded front
approaches from the Delmarva/southern NJ corridor. Meanwhile, a
powerhouse low pressure system associated with a negatively
tilted mid and upper level trough will be moving into the Upper
Midwest and the western Great Lakes Region. This system will be
rapidly deepening and intensifying. An area of upper level
diffluence overspreads the region with a south to southeast LLJ
jet increasing to 35-50+ kt by daybreak, as this should allow
the pcpn to blossom and increase across the entire forecast
area. Based on the latest 12Z HREFS, and the NAM BUFKIT profiles
the greatest threat icing of a tenth an inch or so will be over
the higher terrain, such as the northern Berkshires, southern
Greens, and perhaps the eastern Adirondacks. Most other
locations will likely receive a coating to less than a tenth,
as temps should be rapidly moving upward towards daybreak, as
transition to plain rain is expected especially from Capital
District southward. Lows will be in the 20s to lower 30s, and
then rise after midnight. Some slick spots may be around the
region with the light icy mix. Total snow and sleet will likely
be a coating to maybe an inch in a few spots such as the
southern Greens.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
High Wind Warning in effect from 7 pm EST Sunday to 7 pm EST
Monday for all of eastern NY, except for the mid Hudson Valley
and southern Taconics...
A High Wind Watch is in effect for southern VT and the
Berkshires from 7 pm EST Sunday to 7 pm EST Monday...
A High Wind Watch is in effect for the mid Hudson Valley of
eastern Ulster, Dutchess, and Litchfield Counties (in NW CT)
from 10 pm Sunday to 7 pm Monday...
Tomorrow...The secondary coastal low quickly approaches with a
strong south to southeast LLJ. The 12Z GEFS indicates an H850
+v-wind anomaly /southerlies/ of +2 to +4 STD DEVs above normal
with PWATS briefly getting to +1 to +2 STD DEVs above normal.
Some gusty southeast winds are possible off the western New
England higher terrain and the Taconics in the 30-40 mph. The
pcpn should continue most of the morning, and be enhanced a bit
as the region will be near the left front quadrant of an H250
125-150 jet streak. We did keep the freezing rain threat in east
of the southern Greens Mtns, over the northern Berkshires, and
near the eastern Adirondacks, and the Lake George Region. Temps
finally warm above freezing by the late morning. A tenth or so
of flat ice is possible in a few spots. The NAM/GFS/ECMWF
continue to hint at a dry slot punching into the forecast area
for the afternoon allowing the pcpn to become a bit intermittent
and light. We believe the greatest chance for a lull in the
pcpn is from the Capital Region, and the eastern Catskills south
and west. Temps continue to be very tricky, as the METMOS is
about 7-10 degrees cooler than the warmer GFS MOS. We went about
a 3 degrees cooler than the GFSMOS which is closer to a
superblend and even the EC MOS with upper 30s to lower 40s north
and east of the Capital Region, and mid to upper 40s from the
Capital Region, Mohawk Valley south and east. There could be a
few 50F readings in the Mid Hudson Valley. A secondary low moves
into northern New England, as some cooler air gets drawn back
into the region with a preliminary sfc trough or cold front
moving through with H850 temps falling back to 0C to -5C by
00Z/MON. The winds will begin to increase from the west to
southwest at 15-25 mph with some gusts to 40+ mph, but a strong
frontal passage is expected for the overnight period with a
better surge of cold advection.
Sunday night-Monday...Low pressure continues to deepen and
intensify to 970-975 hPa northeast of Lake Huron and Georgian
Bay. Secondary cold front moves through between 06Z-12Z/MON with
very strong cold advection with H850 temps falling to -10C to
-13C by daybreak.
The low-level sfc pressure gradient increases,and the H850
12Z GEFS +u component of the wind /westerlies/ increases +3 to
+4 STD DEVS above normal. We started the high wind warning early
for eastern NY based on the strengthening winds and the
possibility of starting to transfer momentum from 2-3 kft AGL
of 40-45+ kts at 2-3 kft AGL in the early to mid morning hours.
The isallobaric rise/fall couplet is most impressive over the
northern half or two thirds of the forecast area 8-12 hPa/6-hr
rises between 12Z-18Z, and 18Z-00Z. The funneling down the
Mohawk Valley into the Capital Region should be impressive with
an H925 jet of 45-55 kts. The other concern is that if we mix
deeper to 3-4+ kft AGL we could bring down to the sfc some gusts
in the 50-55+ kt range or so. We believe fairly widespread
damaging winds of 55-65 mph are possible. We upgraded most of
eastern NY to a High Wind Warning. Some locations in the Upper
Hudson River Valley may only get gusts of 45-55 mph, but
downsloping off the Adirondacks could produce damage. How often
do you see the 10-m winds on the GFSMOS product for Albany at 36
kts (at 18Z/MON)?!? A high impact high wind event is expected.
We did expand the High Wind Watch to include the mid Hudson
Valley and NW CT based on collaboration with WFO`s OKX and BOX.
Damaging winds are possible here. We also kept the Watch going
for southern VT and the Berkshires. Likely these areas may need
to be upgraded later or at the very least a Wind Advisory.
Bottom line, we are expecting winds of 20-40 mph with some gusts
up to 65 mph in the warning area, and these may be possible in
the continued Watches. Widespread power outages will be
possible.
The other issue will be upslope/lake enhanced or eventually lake
effect snow for the western Adirondacks shifting into the
western Mohawk Valley Sunday night into Monday. Right now, we
have 3 to 6 inches of snow, which would be advisory levels. This
snow may blow all over the place. We included areas of blowing
snow. We were not confident for a Watch, but will continue to
monitor. A transitory band of lake effect snow may push
southeast into the Mohawk Valley late Monday. We will also have
to watch out for some snow showers or isolated squalls sneaking
down the valley. Parts of the southern Greens could get 1-3+
inches of upslope snow. Lows Sunday night will be in the teens
to lower 20s over the higher terrain, and 20s in the valleys.
Highs Monday will be tricky with the cold advection and
downsloping. We did not go as warm as the GFSMOS guidance. We
went with some lower to mid 30s in the Hudson River Valley
including the Capital District and NW CT. Teens to mid 20s over
the mountains, and mid and upper 20s in the other valley areas.
Monday night...Another sfc trough or cold front moves through
as the winds veer more to the northwest. H850 temps low to -18C
to -26C across the region. Multi-bands of lake effect are
possible over central NY possibly nicking the western Mohawk
Valley and getting into the eastern Catskills, and Schoharie
Valley. Lows fall back into the single digits and teens. Some
below zero readings are possible over the southern Adirondacks.
The winds will begin subside but will still be from the
northwest at 15-25 mph or so overnight. Any lake effect snow
accums will be on the light side. Wind chills may get close to
advisory levels over the southern Dacks (around 20 degrees below
zero). Expect single digits to 10 below zero readings in many
locations
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Global models continue to struggle with consistency throughout
the extended period. However, they are in agreement that
temperatures will remain below normal through the work week
before warming back towards normal levels by the weekend.
To start, lake effect snow showers will be tapering off on
Tuesday as high pressure moves towards the region. Winds will
remain breezy with temperatures in the low teens and 20s during
the afternoon. As high pressure settles in overhead Tuesday
night, temperatures will drop below zero in the Dacks, with
mainly single digits elsewhere. Wind chills may drop towards the
-20 degree mark in the Dacks so wind chill advisory may be
needed. However, winds should diminish quickly.
The rest of the work week looks dry except for a chance for
snow Wed into Wed night. Global models are polar opposites
regarding this potential so have kept mainly slight chance pops
in the forecast. Behind this potential system, ridging builds
into the region resulting in gradually moderating temperatures
and partly sunny skies.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
High and mid level clouds will increase across the terminals
this evening, with cigs gradually lowering. A complex storm
system will approach the region from the western Great Lakes
Region and the Mid Atlantic states tonight, bringing a wintry
mix of precipitation to the terminals spreading from south to
north. At onset of precip, a mix of sleet and freezing rain is
expected, although there could be a brief period of snow as well
at KPSF/KGFL. Precip expected to begin around 04Z at KPOU,
around 06Z at KALB/KPSF, and around 08Z at KGFL. Conditions will
lower to MVFR, and eventually even IFR at KPSF/KPOU late
tonight. Mixed precip will change to rain early Sunday morning
at KPOU/KALB/KPSF, then eventually at KGFL by Noon. Rain will
taper off to scattered showers during the afternoon.
Low level wind shear will develop by early Sunday morning, as a
southeast jet moves overhead. Winds between 35-50 kt at 2000 ft
AGL expected through early afternoon at all terminals. The
southeast jet will move off to the east during the mid to late
afternoon hours, ending the threat for LLWS.
Surface winds overnight will be east-southeast around 5-10 kt,
becoming south-southeast on Sunday. Strong westerly winds will
develop after 00Z Monday.
Outlook...
Sunday Night: High Operational Impact. Very Windy Chance of SHRA...SHSN.
Monday: Very High Operational Impact. High Winds Chance of SHSN.
Monday Night: Moderate Operational Impact. Windy NO SIG WX.
Tuesday: Low Operational Impact. Breezy NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: Low Operational Impact. Slight Chance of SN.
Thursday: No Operational Impact. NO SIG WX.
&&
.HYDROLOGY...
No hydrological significant impacts the next several days.
Another period of wintry mixed precipitation is expected tonight
before changing to all rain on Sunday late morning into the
early afternoon. Rainfall is expected to continue through the
day Sunday, with total QPF amounts generally between a third to
three quarters of an inch with localized higher amounts.
The rainfall, combined with warmer temperatures, will promote
some brief snowmelt and some minor rises on area rivers. The
latest MMEFS this afternoon continues to show no flooding at
this time but will continue to monitor. The tidal gauge at
Poughkeepsie may hit the alert or caution stage late tomorrow
afternoon.
Colder air moves back into the region late Sunday into Sunday
night with lake enhanced or lake effect snowfall the main
precipitation type into Monday night. Cold and mainly dry
weather is expected for Tuesday, and some light snow or snow
showers for the mid week. Flows should lower quickly, and colder
than normal temps are expected for the mid to later portion of
the week. Some ice thickening and reformation is possible.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 7 AM EST Sunday for CTZ001-013.
High Wind Watch from Sunday evening through Monday evening for
CTZ001-013.
NY...High Wind Warning from 7 PM Sunday to 7 PM EST Monday for
NYZ032-033-038>043-047>054-058>061-063-082>084.
Winter Weather Advisory until 7 AM EST Sunday for NYZ032-
038>040-047>054-058>061-063>066-084.
High Wind Watch from Sunday evening through Monday evening for
NYZ064>066.
Winter Weather Advisory until 10 AM EST Sunday for NYZ033-
041>043-082-083.
MA...Winter Weather Advisory until 7 AM EST Sunday for MAZ025.
Winter Weather Advisory until 10 AM EST Sunday for MAZ001.
High Wind Watch from Sunday evening through Monday evening for
MAZ001-025.
VT...Winter Weather Advisory until 10 AM EST Sunday for VTZ013>015.
High Wind Watch from Sunday evening through Monday evening for
VTZ013>015.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...JPV/Wasula
SHORT TERM...Wasula
LONG TERM...JLV
AVIATION...JPV
HYDROLOGY...BGM/Wasula
Area Forecast Discussion
National Weather Service Boston/Norton MA
1041 PM EST Sat Feb 23 2019
.SYNOPSIS...
High pressure builds across the Maritimes tonight. Low pressure
then tracks along the coast Sunday with a wind-swept rain
during the morning tapering off to drizzle in the afternoon. The
exception will be inland where freezing rain/ice during the
morning before changing over to all rain mid to late morning.
Strong to damaging winds develop Sunday night, peaking Monday,
then gradually diminishing into Tuesday. Then bitterly cold
weather overspreads the region Tue night into Wednesday. Not as
cold Thursday and Friday followed by potential winter weather
around next Saturday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
No major changes to the forecast this evening. Low level
humidity still has to increase a bit more before steady
precipitation will reach the ground. Still thinking this will
occur after midnight, but may be a little later than previously
thought. Temperatures will be critical, and will be monitored
closely overnight. Winter Weather Advisories continue for the
threat of freezing rain.
Otherwise, brought the forecast for the next several hours back
in line with observed trends.
715 PM update...
18z models and latest HRRR have slowed onset of precip to about
09z/4 am western CT/MA including Hartford/Springfield then
entering eastern MA/RI around 12z/7 am or thereafter. This
seems reasonable based on latest radar trends and surface
observations with light rain just entering eastern PA and NJ at
7 pm. Part of the reason is downstream upper air pattern is
amplifying with time courtesy of 954 mb low in the north-
central Atlantic. This will result in a slower departure of the
mid level ridge and cold/dry high pressure currently over
eastern Quebec and Maine. Earlier discussion below.
=====================================================================
*** Winter Weather Advisory For Interior Southern New England ***
Dense CI shield has prevented mixing from reaching its full
potential this afternoon, combine this with a slightly colder
than expected start and temps have struggled a bit to reach
initial forecast highs and are generally cooler than forecast.
With highly amplified pattern led by sub 970mb low pres in the
W Atlantic, guidance trend over the last 24-48 hours has been
slower with the onset of isentropic precip shield moving across
the region late tonight, with timing now suggesting it is just
barely reaching W CT after 06Z. This will give more time for
diurnal cooling, which considering the colder than forecast
start, should allow for several locations to dip below freezing,
especially taking wet-bulb processes into account as dwpt
depressions are 5-10F by 03Z.
Meanwhile, as the warm front lifts N, frontal wave looks to
initialize near NJ/Delmarva region within modest convection.
This become elongated as the warm front shifts N and likely
lifts into S New England through Sun afternoon. There is a noted
ageostrophic response to this development, as lower lvl
ageostrophic flow shows strong N component especially areas W of
the Worcester Hills through at least 12-14Z. Given the gradient
flow is more E than SE, there is less opposition to the N
ageostrophic component. With this in mind, will lean more
heavily on the coldest available guidance through the morning
hours, which suggests broader area of PL/SN changing rapidly to
rain along the E and SE regions, but yielding a higher risk for
FZRA across the interior, especially where NOHRSC suggests
continued modest snowpack.
Will expand the Winter WX Advisories to include N CT and N RI as
a result, and lengthen timing for the E Slopes of the Berkshires
and Worcester Hills where ageostrophic northerlies last the
longest. Final SN/PL totals still well under an inch, with ice
totals T-0.25 inches possible, highest in the higher terrain and
where advisories are out the longest.
The advancing warm front, combined with diurnal mixing should
lead to enough sfc warming for a change to rain between 12Z-15Z
from S-N across the region, ending the risk for further ice
threat.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
10AM Sunday through Sunday evening...
With a full change to rain as sfc temps warm above freezing,
attention will shift toward how far N warm sector is able to
reach. The slightly amplified, less progressive pattern hinted
at suggests that the warm front may not lift as far N as
previously though, but looking at a combination of both mass
fields and low-mid lvl thermal profiles, it may reach as far N
as the CT/RI border with MA before meso-low and approaching cold
front forces the entire frontal system eastward during the mid-
late afternoon. With this possibility, there is a low risk for a
brief heavier downpour and even a low risk for a rumble of TS
across mainly SE MA, Cape/Islands with a bit of MU CAPE within
the warm sector. The primary risk would be enhanced rainfall
rates with localized higher totals than the widespread QPF
values of 0.5-0.75 forecast.
As the cold front approaches, mid/upper lvl dry air will be
filtering in, so anticipate transition from RA to a mix of DZ
and BR late afternoon/evening from SW-NE until ana-frontal
mixing can dry out the lower lvls late. Therefore, expect damp
conditions most of the day. Highs in the mid-upper 40s for those
who do get to the warm sector, upper 30s to low 40s further N.
Sun night...
The combination of CAA and dry air entrainment will erode the
lingering fog/low cloud and drizzle through the evening hours.
CAA will be strong, combined with a very robust sfc pres
gradient building as low pres deepens below 970mb near the
Maritimes. Winds should remain below high wind criteria
overnight predominantly due to diurnal inversion development
limiting mixing. However by early AM Mon, the CAA and pres
gradient should overcome the diurnal trend such that gusts could
begin to reach at least wind advisory thresholds. High Wind
Watches were expanded to the remainder of the area during the
overnight hours, although the strongest winds will hold off
until the daylight hours Mon.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
*/ Highlights ...
- Strong to damaging with scattered power outages Monday
- Bitterly cold Tuesday night into Wednesday
- Wintry precipitation possible around next Saturday
Monday ...
Very strong signal for damaging winds and scattered power outages
Monday as low pressure bombs down to 969 over Maine late Monday.
Meanwhile Arctic high pressure at 1040+ mb builds into the high
plains. This creates about a 72 mb pres difference between these two
systems and into New England! In addition cold air advection yields
very steep low level lapse rates with blyr depths to almost 800 mb
with 60-70 kt at this level! Even taking the average Blyr winds via
BUFKIT soundings yields 50-60 kt. Thus above average forecast
confidence (very little forecast uncertainty) that wind gusts of 55
to 65 mph will be common Monday across the entire region. This will
be sufficient for at least scattered tree damage and power outages
region-wide. Thus have issued a High Wind Watch for the entire
region. Wouldn`t be surprised if isolated wind gusts exceed 70 mph
given parameters above along with some downslope acceleration.
Core of cold air is delayed until Tue ngt and Wed so highs Mon in
the 30s but will feel like it`s in the 20s given the very strong
winds. Other than a spot flurry/isolated snow shower via lake effect
connection, dry weather prevails.
Tuesday and Wednesday ...
Very windy Tue but not quite as strong as Monday but second pulse of
strong winds arrive later Tue/Tue ngt with arctic front. Low risk
for snow shower/flurries given lake effect connection continues.
However the big story will be the arctic cold with new 12z EC
offering 925 mb temps Wed morning down to -22C across northern MA!
These values are about -2 to -3 standard deviations below climo.
Thus have blended in some of the colder guidance to reflect this
extreme airmass. In fact thickness may fall just below 500 dam early
Wed! Highs only in the teens and 20s both days with Tue ngt mins in
the single digits and teens but much colder wind chills given
blustery WNW winds.
Thursday and Friday ...
Arctic high builds over the region but winds diminish and airmass
modifies so temps rebound into the 30s. Dry weather Thu but will
have to watch a low amplitude short wave Fri that may bring some
light wintry precip.
Saturday ...
Day 7 here but models have been advertising potential Pacific and
Gulf moisture approaching the region with parent low cutting across
the Great Lakes while secondary low possibly develops somewhere Mid
Atlc region.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Sunday Night/...High confidence.
1040 PM Update...
Previous forecast still looks to be on track. No major changes.
715 pm ...
Not much change from previous TAFs. Onset of precip a bit slower
than previously thought with latest 18z guidance indicating
precip arrives into western MA/CT around 09z and then into
eastern MA/RI around 12z or thereafter. Earlier discussion
below.
================================================================
Through Midnight Local...
VFR. Gradually lowering CIGS and precip approaching from the
W-SW, but it should remain out of the area until after midnight
for all but the very far W MA/CT terminals. Winds light and
variable, but with a slight bend to the east thanks to sea
breezes until the overall wind takes over.
After midnight into late Sunday...
Gradual drop to predominantly IFR with timing off a bit in the
TAFs possible. Mid of FZRA/PL especially interior MA/CT through
the early morning hours, with all rain expected especially after
15Z. Some light ice accums possible especially at terminals in
higher terrain. Mix of BR/DZ will allow the IFR conditions to
linger into Sun evening. Some LLWS especially across SE MA.
Sun night...
Improvement to VFR as BR/DZ ends during the evening. However
winds will be gradually increasing through the overnight hours
with gusts as high as 30 kt out of the W-NW by sunrise Mon.
KBOS Terminal...High confidence in TAF. If any PL/FZRA is
observed, it would be very short-lived, with little to no
accumulation expected.
KBDL Terminal...High confidence in TAF.
Outlook /Monday through Thursday/...
Monday: VFR. Strong winds with gusts up to 60 kt.
Monday Night: VFR. Strong winds with gusts up to 45 kt.
Tuesday through Tuesday Night: VFR. Windy with gusts up to
35 kt.
Wednesday: Mainly VFR, with local IFR possible. Breezy. Slight
chance SHSN.
Wednesday Night: Mainly VFR, with areas IFR possible. Breezy.
Chance SHSN.
Thursday: VFR.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Sunday Night/...High confidence.
Quiet boating weather continues into the evening hours, with
rain/fog overspreading the waters mainly after midnight tonight.
Mix of rain/fog and winds to near Gales expected during the day
on Sunday, mainly out of the east.
Strong W-NW wind gusts begin Sunday night with Storm Gusts
possible as early as midnight Sun night mainly across the S
waters. This expands to all waters by Mon daybreak.
Outlook /Monday through Thursday/...
Monday: Moderate risk for storm force winds with gusts up to
50 kt. Rough seas up to 18 ft.
Monday Night: Moderate risk for gale force winds with gusts up
to 45 kt. Rough seas up to 15 ft.
Tuesday: Moderate risk for gale force winds with gusts up to
40 kt. Rough seas up to 11 ft.
Tuesday Night: Low risk for gale force winds with gusts up to
40 kt. Areas of rough seas.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of snow showers. Areas of visibility 1 to
3 nm.
Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of snow showers. Visibility 1 to 3 nm.
Thursday: Winds less than 25 kt. Local rough seas.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...High Wind Watch from Sunday evening through Monday evening for
CTZ002>004.
Winter Weather Advisory until 7 AM EST Sunday for CTZ002>004.
MA...High Wind Watch from Sunday evening through Monday evening for
MAZ002>024-026.
Winter Weather Advisory until 7 AM EST Sunday for MAZ005-006-
010>013.
Winter Weather Advisory until 10 AM EST Sunday for MAZ002>004-
008-009-026.
RI...High Wind Watch from Sunday evening through Monday evening for
RIZ001>008.
Winter Weather Advisory until 7 AM EST Sunday for RIZ001.
MARINE...Storm Warning from 3 AM to 7 PM EST Monday for ANZ231>234-250-
251.
Storm Warning from 9 AM to 7 PM EST Monday for ANZ230-236.
Storm Warning from 1 AM to 7 PM EST Monday for ANZ235-237.
Storm Warning from 11 PM Sunday to 7 PM EST Monday for
ANZ254>256.
&&
$$
SYNOPSIS...Nocera/Doody
NEAR TERM...Belk/Nocera/Doody
SHORT TERM...Doody
LONG TERM...Nocera
AVIATION...Nocera/Doody
MARINE...Nocera/Doody
AREA FORECAST DISCUSSION
National Weather Service Burlington VT
702 PM EST Sat Feb 23 2019
.SYNOPSIS...
The weather will become unsettled across the North Country tonight
through Monday as a low pressure system moving through the Great
Lakes will bring a wintry mix to the area tonight into Sunday
morning before a changeover to all rain Sunday afternoon, and back
to snow Sunday night. Strong and gusty winds ranging from 25 to 50
mph are also expected across portions of the area. Colder air
returns to the region next week with highs in the teens and single
digit lows through Wednesday night.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 611 PM EST Saturday...Updated to capture latest trends in
temps/dpwts and clouds based on crnt obs/satl data. Temps have
fallen quickly this evening across eastern/central VT valleys
with many locations already in the mid 20s. Have bumped temps
down several degrees to capture the rate of fall this evening,
but expect as clouds and pres gradient increases, temps will
rise aft midnight. Lows generally range from teens nek to
mid/upper 20s. Idea of mixed precip developing after midnight
looks good with a messy and slippery driving conditions expected
Sunday morning. Besides the wintry mix, still anticipating a
period of gusty southeast winds btwn 15z-20z Sunday for the
western slopes of the Greens and northern slopes of the dacks.
Localized gusts up to 45 mph possible with a few isolated power
outages possible. Have continued to cover this potential in the
crnt wsw product.
As powerful 972mb low pres or so races across the Central Great
Lakes into southern Canada on Sunday, very strong and gusty
southwest to west winds develop by Sunday evening. The 21z RAP
shows an impressive 70 to 75 knots 850mb jet couplet passing
across northern NY btwn 07-12z Monday, with soundings suggesting
good deep layer mixing under strong low level caa. High wind
warning looks reasonable based on magnitude of low level wind
fields and depth of mixing potential, which support sfc wind
gusts to at least 60 mph. Would not be surprised a few locations
are 65 mph or so, especially in the Potsdam to Malone areas. In
addition, occasional snow showers will occur, creating hazardous
driving conditions with areas of blowing and drifting snow and
poor vis. The threat for gusty winds shift into VT overnight
Sunday into Monday with localized gusts up to 55 mph likely.
Expect areas of scattered power outages, with some localized
areas of widespread outages anticipated over northern NY. All
covered well in grids and crnt headlines.
Previous discussion below:
Messy weather anticipated through the next 24 hours as a strong
low pressure system moves from the Midwest across the Great
Lakes to our west. Increasing moisture and warm air advection
out ahead of the low will result in a wintry mix of
precipitation, moving in late tonight and continuing through
Sunday morning. Snow will transition to a mix of sleet and
freezing rain, then eventually changing over to just plain rain
by early afternoon from the Green Mountains westward. East of
the Greens, the colder air will be tougher to scour out, so
those areas will continue to see pockets of freezing rain
through the afternoon. Overall QPF amounts will be fairly light,
so snow/sleet will mainly be an inch or less, with up to a
tenth of an inch of ice. This will be enough to cause slick
roads and hazardous travel, so have continued with the Winter
Weather Advisory for the entire area for tonight through Monday.
The other concern for tomorrow will be gusty southeast winds that
will develop during the morning hours in response to the
strengthening low drawing near. Those favored downslope regions
along the western slopes of the Greens and Adirondacks could see
some localized gusts around 50 mph, peaking during the mid to late
morning hours. These wind gusts will be brief and localized,
especially since mixing will not be optimal during the expected
peak, so while some branches or trees may come down, have opted not
to issue any headlines during this time, instead focusing on the
more widespread event for Sunday night and Monday (see Short Term
discussion below).
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 339 PM EST Saturday...The main concern for this time frame will
be widespread strong winds across the region. This will be in
response to the aforementioned low pressure system lifting up to our
northwest, deepening to an impressive 970mb as it does so. Winds
will turn to the west/southwest Sunday evening after a cold frontal
passage, and this cold air advection will make for optimal mixing
and steep low level lapse rates. With a 60+ kt 850mb jet swinging
through, anticipate widespread gusts of 50+ mph. The Saint Lawrence
Valley will see some channeling due to the favorable southwest
direction, along with downsloping on the backside of the northern
Adirondacks. These areas will likely see gusts of 60 mph or more,
peaking late Sunday night into early Monday morning. Have therefore
issued a High Wind Warning for these areas for Sunday evening into
Monday morning. For areas from the Champlain Valley eastward, west
winds will intensify a bit later than over northern NY, and not be
quite as strong owing to the distance from the low center/core of
the jet. Still anticipate gusts up to 55 mph however, especially
from mid to late Monday morning. Accordingly, a Wind Advisory has
been issued for these areas from Sunday evening through Monday.
The cold front and west winds will also serve to switch
precipitation from rain back to snow through Sunday evening, and
allow it to become more focused in the mountains. This persistent
wrap around will likely bring a few inches of snow to the northern
Greens and Adirondacks Sunday night and Monday, before the showers
wind down Monday night. Temperatures will likely fall through the
day Monday, or at best hold steady, with highs in the mid to upper
20s. Colder air begins to settle over the region in earnest Monday
night; lows will be in the single digits above zero in the wider
valleys while the higher elevations will see temperatures drop below
zero.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 339 PM EST Saturday...Large surface high will be established
with northwesterly flow keeping temperatures below average Tuesday
and Wednesday with dry weather. The upper ridge will be positioned
overhead by late Wednesday with flow briefly becoming southwesterly.
The brief, southwest flow comes from a weak clipper system
interacting with a weak surface trough along the thermal gradient
across southern New England. Greater than usual model spread is
evident among the GEFS with some uncertainty as to how far north
precipitation extends to the north of the clipper system. It appears
the system will be piece- meal and relatively unorganized with the
less aggressive FV3 approach more likely. Will maintain the previous
forecast philosophy and keep 20-30% chance of snow late Wednesday
favoring the southern Adirondacks and southern VT. The clipper is
already gone by Thursday morning with high pressure returning. A
gradual warming trend will take place bringing us closer to seasonal
norms. True to the pattern of the last month, a few dry days will be
followed by another system coming in Saturday.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Through 00Z Monday...TAF forecast will start off quiet with
high and mid-level clouds thickening and lowering through the
early overnight hours in advance of the next system to impact
the area. Ceilings will drop to 1000 ft to 3000 ft between 06Z
and 12Z as a warm front moves in and spreads mixed precipitation
through the area. Precipitation will generally start off as some
very light snow or snow/sleet mix after 06Z, then become a
wintry mix of snow, sleet, and freezing rain between 10Z and 15Z
before most areas change over to plain rain by late morning. The
exception will be areas of Vermont east of the Green Mountains,
including KMPV, where warm air will be slower to arrive and snow
and sleet will hold on through the afternoon hours. Winds will
be southeasterly under 10 kts through 06Z, then increase to 15
to 25 kts through late morning with gusts to 40 kts possible
between 15Z and 20Z. Highest gusts are expected along the
western slopes of the Green Mountains (including Rutland) and
along the northwestern slopes of the Adirondack Mountains.
A very strong (70+ kt) low-level jet will push through the area
between 12Z and 21Z, so some low-level wind shear can be
expected at terminals that don`t see gusty winds at the surface.
This will especially be a concern at KSLK and KMSS. In addition
to low-level wind shear, turbulence will be a concern,
especially over the northern Adirondacks in New York and along
and west of the Green Mountains in Vermont.
Outlook...
Sunday Night: Mainly VFR, with local MVFR possible. Strong winds
with gusts to 50 kt. Chance SHSN, Chance SHRA.
Monday: VFR. Strong winds with gusts to 40 kt. Chance SHSN.
Monday Night: VFR. Strong winds with gusts to 40 kt. Chance SHSN.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Slight chance SN.
Wednesday Night: VFR. Slight chance SN.
Thursday: VFR. NO SIG WX.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Winter Weather Advisory from midnight tonight to 9 AM EST
Sunday for VTZ001-002-005-009-011-016>019.
Wind Advisory from 7 PM Sunday to 7 PM EST Monday for
VTZ001>012-016>019.
Winter Weather Advisory from 3 AM to noon EST Sunday for
VTZ003-004-006>008-010-012.
NY...High Wind Warning from 4 PM Sunday to 1 PM EST Monday for
NYZ026-027-029>031-034-087.
Winter Weather Advisory from midnight tonight to 9 AM EST
Sunday for NYZ026>031-034-035-087.
Wind Advisory from 7 PM Sunday to 7 PM EST Monday for NYZ028-
035.
&&
$$
SYNOPSIS...Hastings
NEAR TERM...Hastings/Taber
SHORT TERM...Hastings
LONG TERM...Haynes
AVIATION...RSD
Area Forecast Discussion
National Weather Service Columbia SC
1035 PM EST Sat Feb 23 2019
.SYNOPSIS...
A frontal system will remain in the region through tonight. A
cold front will cross the area Sunday with a dry air mass
overspreading the region during the afternoon. Dry high pressure
will be in control Monday and Tuesday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Surface conditions also showing the surface wedge still holding
strong over the cwa. This is expected to continue the nest
several hours. Satellite loops showing very little movement
along the southern edge of the wedge so far. Winds closer to the
approaching cold front over northwestern GA are showing more of
a south to southeasterly direction, indicating that the wedge
is attempting to weaken and break in that area. Wedge should
remain for much of the night, then begin to lift northward late
tonight just ahead of the cold front. This will keep
temperatures generally in the 40s for a good portion of the
night, then as the wedge begins to lift late tonight,
temperatures should begin rising.
Regional radars continue to show little in the way of rainfall
across the cwa. Nearest rain includes one small batch of showers
along the coast around KSAV, with additional rainfall moving
into northwestern SC ahead of an approaching front. Guidance
generally keeps the rainfall out of the cwa for much of the
night, bringing showers into the western cwa closer to sunrise
just ahead of the cold front. For much of the night, expect
drizzle and fog to develop and possibly become dense at times
as the wedge weakens.
Latest hrrr generally keeps LI values above zero, with some
weak instability possible towards morning due to the wedge
weakening and warmer temperatures pushing into the area.
Expecting mainly rain showers, with possibly an isolated
lightning strike towards sunrise. Overall thunderstorm threat
remains low.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Cold front will cross the forecast area Sunday morning with a
relatively thin line of showers expected as it passes. Despite above
normal PWAT values above 1.5 inches accompanying the front,
925mb/850mb flow will be from the west and downsloping a bit which
will limit rainfall accumulations to less than a quarter of an inch.
Colder air behind the front will be lacking as very warm 850mb
temperatures will be mixing down with the drier air building in
behind the front resulting in well above normal high temperatures in
the 70s. The wind will be one of the higher impact features of the
day as winds will gradually veer to the west behind the front and
increase to 15 to 20 mph with gusts as high as 30-35 mph at times
through the afternoon. A Lake Wind Advisory may be required.
High pressure will settle over the area on Monday under mostly clear
skies and relatively light winds. A light southerly wind will
develop by Tuesday afternoon as the surface high shifts offshore and
some higher clouds move into the region. Temperatures will be near
normal in the 60s both Monday and Tuesday with Tuesday being
slightly warmer but no rain in the forecast either day.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Little change in the thinking regarding the extended forecast today
with medium range models continuing to show some general consensus
in the overall upper pattern. Generally westerly 500mb flow expected
through the period with difficult to time shortwaves moving through
the flow with the GFS being a bit more wet with a few shortwaves
bringing rain to the region Wednesday and again Thursday night into
Friday with a stronger digging trough and front providing another
chance of rain on Saturday. The ECMWF shows a drier forecast with
suppressing the initial shortwaves to the south but also shows the
stronger shortwave for Saturday with rain chances. Will maintain a
persistence forecast until there is better certainty. Temperatures
should generally be near to slightly above normal through the period
although there are some significant differences among the GFS/ECMWF
on Thursday with max temps ranging from lower 70s to mid 50s.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
Expect IFR/LIFR conditions through 12-15Z...improving to MVFR
15-18Z and VFR/breezy after 18Z. Low level wind shear will exist
at all terminals after 03Z...lingering through 15-17Z.
Deep low-level moisture in place in current cold air wedge with
stationary front in southern Georgia...poised to move northward
tonight. SE-SW low-level jet will begin transporting warmer air
northward after 06Z which will strengthen warm air overrunning
of the cold airmass in place. This will continue to support IFR
conditions in stratus/fog/drizzle at all terminals with LIFR
likely as the warm front approaches on its way northward,
starting at AGS/DNL first. As the 30-45 kt low-level jet
establishes after 03Z expect LLWS.
Satellite prognosis and models agree with arrival of a decent
cold front around 10Z at AGS/DNL and 12-13Z at CAE/CUB/OGB. A
sharp increase in winds, a SSW-W windshift and showers will
occur with frontal passage. Stability profiles do not support
thunderstorm development. With thinning low-level moisture,
and G15-25KT winds behind the front, cig/vis will improve to
MVFR and then VFR after 15-17Z.
EXTENDED AVIATION OUTLOOK...High pressure is forecast in the
region Monday and Tuesday with dry conditions and diminished
winds. Widespread restrictions could occur Wednesday associated
with an onshore flow or possible low pressure development just
south of the region.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Charleston SC
937 PM EST Sat Feb 23 2019
.SYNOPSIS...
A warm front will lift north through the forecast area tonight.
Then on Sunday, a cold front will sweep through from the west
and move offshore in the evening. High pressure is expected to
prevail into the middle of next week and an area of low
pressure could pass off the coast late in the week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
The overall thinking has not changed from the previous update.
Sea fog is slowly moving inland along the Georgia and far
southern South Carolina coast, but webcams and surface
observations suggest a Dense Fog Advisory is not yet needed.
Farther inland fog is getting thicker as stratus build-down
commences. Opted to nudge pops to 30% in the Savannah-Beaufort
corridor based on radar and short-term model trends. Also nudged
overnight lows down a few more degrees in some areas per latest
observations. Still expect temperatures to rise overnight as the
warm front eventually overtakes the quasi-stationary wedge front
lurking across the south.
A complex surface pattern is in place this evening as insitu
cold air damming holds across much of North Carolina, South
Carolina and into Georgia. 23/23z surface analysis placed
a stationary wedge front extending from just offshore of the
Charleston County coast to near Hilton Head, then arcing back
inland along the I-16 corridor into central Georgia. North of
the wedge front, fog/stratus with areas of drizzle are common,
while south of the front, much warmer conditions are found with
little in the way of fog/drizzle, except along the immediate
Georgia and far southern South Carolina coast where sea fog is
present. Farther south, a sharpening warm front extended from
roughly Jacksonville, Florida, to Alma, GA, then extending
northwest through central into west-central Georgia near
Columbus, GA. The inland and northward progression of these
features will make for a rather difficult overnight forecast
with a number of forecast challenges to address.
Rain: KCLX/KVAX radars show isolated showers developing just
south of the Altamaha River. This activity appears to correlated
to a small area of enhanced isentropic assent along the 305K
isosurface forming just north of the synoptic warm front. The
23/22z RAP initialized this activity rather well and actually
shows a slight areal expansion over the next several hours as the
region of isentropic lift propagates northeast into parts of
Southeast Georgia and eventually south coastal South Carolina
through 24/06z. Will likely keep pops in the isolated category
for now, but some areas could definitely see a few hundredths
of an inch over the next few hours, including the Savannah Metro
Area. Once this region of lift exits off the middle South
Carolina coast after 1-2 AM, expect a mostly dry night.
Temperatures: A large thermal gradient is in place this evening
with the wedge front bisecting the region. Nighttime lows (6pm-
7am) will likely occur this evening for many locations with
temperatures expected to slowly rise overnight as the wedge
front is eventually overtaken from the south by the synoptic
warm front. By daybreak, temperatures are expected to be in the
mid-upper 60s with breezy conditions. Adjusted nighttime lows
slightly based on current observations and short term trends.
Updated temperatures show lows from the lower 50s across far
interior Southeast South Carolina to the mid 60s along the
Altamaha.
Fog: Coastal webcams, pilot boat reports and a few ship
observations show widespread dense fog has developed across the
nearshore waters of Southeast South Carolina and far southern
South Carolina. This fog is expected to move steadily
inland and north through the evening hours, impacting coastal
Georgia into the Beaufort-Hilton Head areas early, then
spreading well inland and into the Charleston Metro area
overnight. Dense fog is likely to occur with NARRE-TL
probabilities for dense fog running well above 80% in many
areas. Dense Fog Advisories are likely to be issued. The fog is
expected to steadily lift from south-north during the early
morning hours Sunday as the warm front lifts north and low-level
winds increase. Expect the dense fog to mostly clear Southeast
Georgia by 4-5AM and the Charleston Tri-County area by 6-7AM.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
Sunday and Sunday night: A fast moving cold front will approach the
are from the west in the morning and then push offshore by the late
afternoon. Good frontal forcing will result in a band of showers
that should maintain across the forecast area. The best rain chances
will be during the late morning to early afternoon with abrupt
drying taking place behind the front. There are some indications of
very weak instability along and ahead of the front, but not enough
to introduce thunder to the forecast. Temperatures will warm quickly
in the morning with upper 70s and even some low 80s possible
depending on how insolation works out. Southwesterly winds will
become gusty in the morning in the warm mixing ahead of the front,
with gusts into the 25-30 mph range expected. Then behind the front
winds will turn westerly and remain gusty as cooler air starts to
filter in. Through the overnight, skies will clear behind the front
and winds will gradually relax. Lows are forecast to range from
around 40 inland to the mid and upper 40s along the coast.
Lake winds: Wind. around Lake Moultrie will become gusty on Sunday
out of the southwest. Gusts to 25 knots will be possible on the
lakeshore, especially on the south and western sides of the lake.
Then behind a cold front in the afternoon winds will turn more
westerly and northwesterly through the overnight. Gusts to 25 knots
will still be possible and a Lake Wind Advisory could be needed.
Monday through Tuesday: High pressure will prevail through the early
part of the week with quiet conditions. Highs on Monday are forecast
to range from the mid to upper 60s, then into the upper 60s and low
70s on Tuesday. Monday night will bring good radiational cooling
conditions and lows will fall into the upper 30s inland, and mid to
upper 40s along the coast.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Zonal flow in the mid and upper levels will prevail until late in
the week, when a short wave trough is currently forecast to
approach the region. At the surface there remain model differences,
and as such our confidence Wednesday through Friday is low. Due the
uncertainty we have leaned considerably toward the previous forecast
which shows no more than chance PoP`s through the period, while
temps will average above normal as the calendar changes from
February to March.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Widespread fog/stratus is expected to impact both KCHS and KSAV
overnight. The fog could reach KSAV very early, then spread into
the KCHS terminal in the 03-06z timeframe. Vsbys/cigs below
airfield minimums are likely, especially at KSAV where
widespread dense fog is likely. Conditions will improve from
south-north early Sunday as a warm front lifts north, clearing
KSAV by 09-10z and KCHS 11-13z. A period of VFR will occur just
before a cold front pushes through the terminal around 17z. The
front will be accompanied by an area of rain. Introduced 5SM in
-RA for now. West/northwest winds will prevail after FROPA.
Gusty winds will impact the terminal from 12-13z on.
Extended Aviation Outlook: The next chance of any sub-VFR weather
will not be until the middle of next week. Also, gusty SW and W
winds will occur at times Sunday, peaking around 20-25 kt at
both terminals.
&&
.MARINE...
Tonight: Issued a Marine Dense Fog Advisory for the Georgia and
Beaufort nearshore legs through noon Sunday. Widespread dense
sea fog has developed and will move slowly north through the
night, likely impacting Charleston Harbor and the Charleston
nearshore waters. The advisory may need to be expanded later
this evening. Otherwise, winds will turn southerly through the
night with speeds generally holding less than 10 kt. Seas will
average 2-4 ft.
Sunday through Thursday: Southwesterly winds will strengthen and
should help to disperse lingering morning sea fog by the late
morning hours. Winds will become strong enough that Small Craft
Advisories will likely be needed, especially for Charleston Harbor,
the Charleston County waters, and the outer Georgia waters. Then
overnight behind the front, winds will become northwesterly and
remain elevated close to advisory levels. Conditions will then
become much calmer starting Monday as high pressure builds in, well
below advisory thresholds through the latter part of the week.
&&
.CLIMATE...
Record Highs for February 24...
KCHS: 81/2017 and previous
KCXM: 81/1930 KSAV: 86/2012
Record High Mins for February 24...
KCHS: 60/1992 and previous
KCXM: 63/2018
KSAV: 64/1980
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Dense Fog Advisory until noon EST Sunday for AMZ352-354.
&&
$$
Area Forecast Discussion
National Weather Service Des Moines IA
604 PM CST Sat Feb 23 2019
.UPDATE...
Issued at 604 PM CST Sat Feb 23 2019
Portions of the winter weather advisory have been upgraded to a
blizzard warning. List of counties is below and updated headline
product has been sent. /rev
&&
.SHORT TERM.../Tonight through Sunday/
Issued at 313 PM CST Sat Feb 23 2019
...Blizzard Conditions Still Anticipated North and West
The primary concern through the period will obviously remain precip
and wind trends through tomorrow. The long wave trough is currently
moving through the Plains with strong upper level diffluence aiding
broad synoptic scale ascent through the MO Valley. This is preceded
by a potent short wave/PV anomaly across KS which is beginning to
spread notable kinematic forcing into Iowa with strong DPVA and
pressure advection along the the 1.5 PVU surface. This is all phased
with strong thermodynamic support as well with high end warm/theta-e
advection and frontogenetical response. Adding a last layer to the
vertical motion contribution is instability with token MUCAPEs
feeding into the maturing deformation zone and more widespread
negative EPV beyond that. This low static stability is being
realized in smaller convective clusters and narrow SW-NE banding
from KS into IA.
This precip shield was just reaching western sections of the
forecast area at 20z and will quickly spread north and east through
sunset with a mix at first but a quick changeover to snow. The above
factors appear to be essentially steady state as the system moves
through Iowa tonight. With the exception of the 12z ECMWF, most
models have changed little from the current forecast thinking with a
SW to NE stripe of heavy snow from the Denison area toward Algona
and Mason City, with a two to three county boundary either side and
lesser amounts quickly tapering down to an inch. Confidence is low
in these gradient areas with snowfall amounts potentially varying
several inches just across a county. Recent HREF and SREF runs both
have high confidence in 1 inch/hr rates with the HREF even depicting
greater than 70 percent chance of 2 inch/hour rates. Consistent and
more recent RAP and HRRR runs will be favored vs the ECMWF so have
left max axis essentially unchanged and nudged up event total accums
a touch with 10 plus inches now anticipated in the aforementioned
heavy snow axis.
Wind gusts expectations havent changed with widespread 35 to 50 mph
gusts anticipated later tonight into Sunday based on model mixing
projections. Have made minor additions to the Blizzard Warning,
adding a few counties on the south and east flank due to better mesh
with higher snowfall amounts. Impact wise, some power outages may
occur with wet, heavy snow initially with 0-2km 0 to -4C isothermal
profiles at onset before the column cools and winds increase. Also
of note is the potential for weak and/or flat roof structures to be
impacted in the heavy snow axis. Snow depths there are already 6 to
16 inches with an additional 6 to 12 anticipated. One roof collapse
has already recently occurred at a Waterloo school.
The precipitation event itself will not last too long, exiting
northeast Iowa before sunrise. This may be near the time of peak
wind gusts however so significant blowing snow and blizzard
conditions may continue through the day, especially in rural, open
areas. After a buffer zone of Winter Weather Advisory, farther south
and east where appreciable snow is not anticipated the predominate
threat should be wind and a Wind Advisory will remain in effect for
those locations. The winds should subside by Sunday evening leading
to cold temperatures being the primary theme. Widespread sub zero
lows are again expected central and north by Monday morning.
.LONG TERM.../Sunday night through Saturday/
Issued at 313 PM CST Sat Feb 23 2019
The long term remains active but the systems coming across at least
at this point are weaker and do not appear to be big snow producers.
After this weekend system, there will be little rest as a large
Canadian low combined with a building upper ridge across the Rockies
keeps the region in a northwest flow. A shortwave will rotate from
the Northern Plains across the Upper Midwest Monday. At the
surface, high pressure will be over much of the state. Cross
sections show patchy drying in what looks to be fairly shallow
moisture. In addition, models are putting better precip chances
across northern Iowa but the better forcing and theta-e advection
resides from west central Iowa to south central Iowa. Given the
less deep moisture, patchy drying and the displacement of the better
forcing and thermodynamics, snow with this system is expected to be
light...on the order of an inch or less mainly north of highway 20.
Still think this snow band may need to shift further south but will
monitor to see how the surface high develops.
By the time we get to Tuesday, models vary on solutions with the GFS
flattening the ridge as a strong trough drops across the Northern
Plains giving us a more zonal flow. The Euro keeps the upper ridge
building and our area in a northwest flow. Variability with other
models are split between these solutions as well. The similarity is
that they all drop a second weak wave across the region. Theta-e
advection and forcing are a little more focused across northeast
Iowa with this system and moisture is a little better but it may be
better organized east of our forecast area. Since this is the day 4
period, better clarification o n amounts and location will be
attained in the next couple of forecast cycles. High pressure
quickly builds in Wednesday for a cool and dry day.
Late Wednesday night through Thursday morning, another shortwave
sweeps across Iowa and models print out some qpf across southern and
western Iowa but with surface high pressure in place, not sure this
will amount to much. The GFS is far more bullish on this than the
Euro so for now I just have generally lower end chance PoPs going.
By the end of the week, the models develop a far more interesting
looking system with a large Canadian low pushing a deep trough over
the Northern Plains and Upper Midwest. This will surely spell much
colder temps for Iowa next weekend. Models develop snow with this
as well but differ considerably on timing/location. Have high end
chance PoPs across the state during this time but this is just too
far out to assign much certainty to anything. Definitely will be
the system to watch in the next week.
&&
.AVIATION.../For the 00Z TAFS through 00Z Sunday evening/
Issued at 604 PM CST Sat Feb 23 2019
Conditions will drop to VLIFR with near 0 visby for KFOD, and
KMCW...elsewhere possible to see occasional 1/4sm at KDSM and KALO
aft 03-07z as snow hits the area and winds rapidly increase. Very
significant wind gusts will occur from 06-22z over the region as
winds increase to near 30 to 35 kts and gusts exceed 45 kts at
times. Though the boundary layer may briefly decouple between 09z
and 13z...winds expected to again mix deeply to 40 to 45 kts aft
14z Sunday and remain strong much of the remainder of the period.
With that BLSN likely for much of overnight with 1/2sm to 2sm vsby
common even aft 12z Sunday at KMCW/KFOD and 2 to 6sm at KALO and
KDSM at times. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM CST Sunday for IAZ039-049-050-
060-061-072-073-082-083-092-093.
Winter Weather Advisory until 6 PM CST this evening for
IAZ004>007-015>017-023>025-033>035-044>046-057.
Blizzard Warning until 6 PM CST Sunday for IAZ004>007-015>017-
023>028-033>038-044>048-057>059-070-071-081.
Wind Advisory from midnight tonight to 6 PM CST Sunday for
IAZ062-074-075-084>086-094>097.
&&
$$
UPDATE...REV
SHORT TERM...Small
LONG TERM...FAB
AVIATION...REV
Area Forecast Discussion
National Weather Service Hastings NE
824 PM CST Sat Feb 23 2019
.UPDATE...
Issued at 823 PM CST Sat Feb 23 2019
The last of the advisory and warning have been cancelled. There
could still be a few flurries and very patchy blowing snow. There
will probably continue to be some drifting snow in open areas.
UPDATE Issued at 714 PM CST Sat Feb 23 2019
Another chunk of the advisory and warning have ended. Snow
continues to end from west to east across the area this evening.
UPDATE Issued at 604 PM CST Sat Feb 23 2019
Snow is ending in the western part of the forecast area this
evening. There is no restriction in visibility, but there could be
a little drifting snow in open areas. Have cancelled the advisory
in the far west.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 243 PM CST Sat Feb 23 2019
Short term is largely going to plan, but did have to add four
counties on the northwest fringe as a band set up just northwest
of our original blizzard warning. The blizzard warning now
includes Franklin, Adams, Hamilton, and Polk counties. Although
Grand Island has been 1/4SM for the past couple of hours, the edge
of the band lies just to the southeast, and I suspect the 46 mph
wind gusts are helping to knock these visibilities down. We will
have to monitor if the northwest edge of the snow band creeps any
farther northwest. The HRRR and RAP seems to be doing a decent job
on the northwest edge of snowfall. I increased snow amounts an
inch or two over toward Geneva, York, and Osceola areas as the
snow band makes a pivot.
It looks like some snow may hang around a little later into the
evening than previous forecasts, but by 03Z, snow should be pretty
much out of our CWA, with blowing snow continuing to lower
visibility. Kept temps well below guidance for temperatures as
models do not seem to be handling the arctic air well at all. Lows
tonight could hit below zero in our northeast half despite the
wind not completely dying out. We will have some clearing,
however.
Sunday should have sun, but arctic air may keep us from even
achieving teens in the tri-cities, but a bit warmer to our south.
.LONG TERM...(Sunday night through Saturday)
Issued at 243 PM CST Sat Feb 23 2019
Stubborn cold pattern continues for the entire long term.
Temperatures will be well below normal, with highs in the teens
and 20s for the most part. We could see some flurries in the
Monday/Tuesday time frame, but nothing significant.
Next decent shot at snow seems to be Friday next week.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 527 PM CST Sat Feb 23 2019
Snow is rapidly coming to an end in the western part of the area
and visibility is improving. The conditions will continue to
improve for the next couple of hours. There will be some wind
shear toward morning. Skies will be clearing.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
UPDATE...JCB
SHORT TERM...Heinlein
LONG TERM...Heinlein
AVIATION...JCB
Area Forecast Discussion
National Weather Service Grand Rapids MI
936 PM EST Sat Feb 23 2019
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 330 PM EST Sat Feb 23 2019
- Thunderstorms mid to late this evening
- Very windy Sunday through Sunday night with wind damage and
numerous power outages likely
- Colder with snow Sunday through Sunday night
- Blizzard conditions Sunday through Sunday night in central lower
Michigan
&&
.UPDATE...
Issued at 936 PM EST Sat Feb 23 2019
Still getting some reports of icing northeast of GRR, so have
updated the fcst to have a couple more hours of freezing rain
for the Mt Pleasant/Big Rapids areas north. That threat should
end by midnight as the warmer air works north. Tstms are
approaching from the southwest and those should arrive around 11
PM. MUCape peaks around 600 J/KG between midnight and 3 AM, so
best chc during that time. Otherwise latest HRRR showing
widespread 50-55kt wind gusts Sunday afternoon, supporting the
current warnings.
&&
.DISCUSSION...(This evening through next Saturday)
Issued at 330 PM EST Sat Feb 23 2019
Rapid cyclogenesis will occur late today through Sunday as a
998 mb sfc low currently over southeastern Kansas strengthens to
around 972 mb in a position between Sault St Marie and James Bay
early Sunday evening. As noted by our previous shift this strong
of a sfc low will rival the historic fall storms like the 1998
storm, the Fitzgerald storm of 1975 and the Armistice Day storm of
1940.
It will be very windy Sunday through Sunday night as a result of
the pressure gradient between that intense sfc low and a 1040 mb high
over the northern plains states. Wind gusts of up to around 60 to
65 mph are expected which will result in downed trees limbs and
power lines. Numerous power outages are likely. Therefore we will
be issuing a high wind warning for roughly the southern two thirds
of our fcst area.
The strong caa will result in a rapid changeover of rain to snow
mid to late Sunday morning. Snow will then continue Sunday
afternoon through Sunday night as h8 temps plummet to around -18
to -20 C by 12Z Mon. Snow accumulations of an inch or two are
forecast near to south of I-96 although isolated amounts closer to
three inches are possible where lake effect bands are most
persistent.
It is noted that higher resolution short range model guidance has
trended up with qpf and fcst snow accumulations for our northern
fcst area. The 3km nam now shows potential for 5 to 8 inches of
snow near to north of Big Rapids and this notion is supported by
the FV3. So we have raised forecast snow accumulations somewhat
for areas north of I-96 and especially from near Big Rapids
northward.
Blizzard conditions are forecast tomorrow through tomorrow night
up there given the snow in conjunction with wind gusts of 50 to
65 mph. Therefore we have hoisted a blizzard warning for our
northern two tiers of counties (except for Isabella county where
less snow is forecast) for tomorrow through tomorrow night.
Light lake effect snow showers will quickly taper off to just a
few flurries Monday due to the very dry airmass in place by then
and since inversion heights by Monday morning will have crashed
to around 2-3 kft agl.
A broad sfc high pressure ridge will build in to bring a brief
return to more tranquil wx Monday night and Tuesday. However the
next system moving in from the northern Plains states will bring
light snow Tuesday night and Wednesday.
A potentially much stronger system will move nne from the Gulf
Coast region and bring potential for significant snow Friday night
and Saturday. Another shot of arctic air with lake effect snow
showers will follow for the rest of next weekend.
As for late this afternoon and tonight we expect rain showers to
continue across our central and southern fcst area. A wintery mix
of rain/snow/sleet/fzra over our northern fcst area will transition
to plain rain late this aftn/early eve as thermal profiles slowly
moderate up there.
Scattered convection is expected to develop during the mid to late
evening hours tonight as elevated instability increases (h8 li/s
down to -1 to -2) and on the nose of a strong 50-60 kt llj.
Severe wx is unlikely tonight this far north mainly due to weak
instability.
However given this strong of a llj and magnitude of winds in the
lower levels of the atmosphere I would not be surprised if we had
a few strong to marginally severe gusty thunderstorms. The most
likely time frame for these is between 03Z and 07Z tonight.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 710 PM EST Sat Feb 23 2019
The main aviation impact from this storm will be the winds.
Tonight the sfc winds will be easterly at 10 to 20 kts, becoming
southeast 15-25 kts then south overnight. Expect some LLWS since
southerly winds just above the sfc will be increasing to around 50
kts by midnight.
The first big surge of higher sfc wind gusts arrives from the
southwest around 12Z Sunday when gusts to 40 kts are possible,
then the period of highest gusts will be Sunday afternoon and
evening. During this time frequent gusts of 45 to 55 kts are
expected from the west.
IFR conditions will prevail most of time tonight and Sunday,
although a brief period of MVFR or even VFR may occur between
roughly 09z and 13Z Sunday - especially south and east of GRR -
as the dry slot of the system pokes in.
Tonight the IFR conditions will be associated with rain showers,
stratus, and areas of fog. A tstm may even occur between roughly
03Z and 09Z tonight. On Sunday the IFR conditions will be related
to snow and blowing snow, which will be most prevalent and
heaviest in the afternoon.
&&
.HYDROLOGY...
Issued at 330 PM EST Sat Feb 23 2019
A significant warmup as well as rainfall expected this weekend
will start the process of river levels rising again. Anytime we
think about rapid warmups and rainfall this time of year leads to
the logical question about flooding potential. The good news is
that at this point it looks like the rain totals will be low
enough and the warmup will be brief enough to avoid widespread and
significant flooding across our area over the next week. However,
significant rises are very likely on virtually all of our rivers,
and by the first half of next week many of our rivers will again
be near bankfull. We will keep a close eye on forecast trends, but
right now it looks like our rivers should escape without major
issues.
The one fly in the ointment is the renewed threat of ice jams on
some of our rivers. The last big rise on our rivers a few weeks ago
destroyed a lot of the river ice, which will now work to our
advantage (you can`t have an ice jam without ice). Limited amounts
of new ice have formed on parts of the rivers, but most of our
rivers remain mostly ice-free at this time. However, there are some
rivers that still have solid ice covering them, including parts of
the Grand River (Portland, Grand Rapids area, and
Eastmanville/Robinson Township). These areas will be the focus for
potential ice jam formation over the next week, and should be
watched closely.
Once the upcoming warm and windy weather passes, temperatures will
again plunge for next week, which will limit additional snowmelt and
start to give the rivers a chance to recover from all the new
water.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 7 AM Sunday to 7 AM EST Monday for MIZ046-
050>052-056>059-064>067-071>074.
Blizzard Warning from 7 AM Sunday to 7 AM EST Monday for
MIZ037>040-043>045.
&&
$$
UPDATE...Meade
SYNOPSIS...Laurens
DISCUSSION...Laurens
AVIATION...Meade
HYDROLOGY...AMD/63
Area Forecast Discussion
National Weather Service Lincoln IL
945 PM CST Sat Feb 23 2019
.UPDATE...
Issued at 945 PM CST Sat Feb 23 2019
Continued high wind warning central and ne CWA and wind advisory
sw CWA overnight through 6 pm Sunday, and updated NPW product for
this wind headline.
Updated forecast earlier this evening for the areas of dense fog
over portions of central IL north of I-70 and adjusting
thunderstorm chances. Recent update at mid evening was to diminish
the fog from west to east during mid/late evening as SSE winds
shift SSW and increase to breezier levels. A band of showers and
isolated thunderstorms extended from Henry southward along highway
51 with dense fog lifting west of this band of convection as SSE
winds shifting SSW and increase.
03Z/9 pm surface map shows strong 994 mb low pressure near Cedar
Rapids/Marion in east central Iowa with its warm front extending
eastward over northern IL and central IN. Its cold front was over
central MO and into Ozarks of nw AR. Temps have gradually risen
into the mid 40s nw of the IL river at mid evening and upper 50s
from Shelbyville to Charleston/Mattoon to Paris southeast with
Salem up to 61F. Moist dewpoints were close to temperatures.
Models deepen surface low pressure to 982 mb by sunrise as it
ejects ne into northern Lake MI, sweeping a strong cold front
eastward across CWA between midnight and 4 am. Showers and
isolated thunderstorms possible in eastern CWA until midnight,
then wrap around/deformation zone of lighter pcpn to affect mainly
northern/nw CWA overnight with light snow showers possible late
tonight after 3 am. Winds turn west during overnight and increase
to 25-35 mph with gusts of 45-55 mph by late tonight and these
strong winds to continue much of the day Sunday with gusts of
50-60 mph over central and ne CWA in high wind warning. Temps to
fall overnight behind cold front, with mercury levels in upper 20s
and lower 30s by early Sunday morning from I-55 nw and mid to
upper 30s in southeast IL. Wind chills to drop into the upper
teens and lower 20s by sunrise over much of central IL, so a sharp
change from the milder conditions this evening ahead of the cold
front.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 255 PM CST Sat Feb 23 2019
Surface low pressure system off to the west over eastern Kansas
this afternoon is making rapid progress towards the region. Rain
showers continued through the morning, with some ponding already
reported in several areas with rainfall totals less than an inch,
due to snow melt and frozen ground still in place. Warmer air
moving into the area also bringing moisture resulted in some
patchy fog, with a few reports of visibilities less than a
quarter of a mile. The fog will continue intermittently as the
night progresses, with more showers likely until midnight. At that
point, the dry slot should dominate most of Central IL as the low
passes to the north.
The major concern for the forecast tonight is the winds. The upper
low associated with this storm system is negatively tilted
consistently in model depictions as it cross the Mississippi
River Valley. This negative tilt is indicative of a rapidly
developing surface system with a quick tightening pressure
gradient. From 06-09Z the winds strengthen and gusts develop with
momentum transfer maintaining through the overnight hours with the
strong +50kt llvl jet keeping enough turbulence in the boundary
layer. With the sustained winds in excess of 30 mph at times, will
easily hit wind advisory criteria, much less with the gusts up to
50 mph. However, areas NW of a line from roughly Havana to Paris
may end up seeing gusts in excess of 58mph at times, hitting High
Wind Warning criteria. HRRR actually has the gusts at the surface
at the start of the day maxing out in that area. Between the HRRR,
a couple of previous runs of the models, and the tendency of late
for various models to underestimate the winds in Central IL by a
good 5 to 10 mph, have opted to go ahead and replace the High Wind
Watch with a High Wind Warning. Tomorrow will be very windy, with
winds diminishing, but not gone as evening approaches.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 255 PM CST Sat Feb 23 2019
A quick drop in the temperatures for Sunday night through Monday
night will drop Mondays high temperatures to under the freezing
mark for the northern half of the state. After the storm system
passes, much of the country is dominated by zonal flow. The
pattern shift does result in some variations as to the handling of
several quick shortwaves. The GFS brings through a stronger shot
at precip midweek than the ECMWF that keeps it farther to the
north. Some minor pockets of small pops show up in the forecast
with variations in the blended solution. However, a stronger wave
dives into the west coast of the country late Thursday night and
models agree on dropping it into the Rockies and a quick surface
system moving into the Midwest for the weekend. Too early for
details, but it looks like the trend of weekend systems may
continue for Central IL.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 600 PM CST Sat Feb 23 2019
Widespread fog and dense at times into mid evening over central
IL airports with visibilities ranging from 1/4 to 1 mile (BMI has
vsby of 1/8 mile) and ceilings 200 to 300 ft this evening. The fog
should start lifting during mid/late evening as ESE winds 10-15
kts and gusts to 20 kts early this evening shift SSW and increase
to 14-19 kts and gust 20-30 kts. Carried VCSH through mid evening
across central IL. Strong 997 mb low pressure near KC early this
evening, will strengthen to 989 mb as it tracks toward Madison in
south central WI by 06Z/midnight tonight and sweeps a strong cold
front east over central IL. Surface low deepens to 971 mb by 6 pm
Sunday as it tracks toward the Ontario/Quebec province line. Have
LLWS this evening and early overnight with 2k ft sw winds of 45-50
kts. Winds switch sw behind cold front overnight and WNW by dawn
Sunday and increase to 25-35 kts by sunrise with gusts of 40-50
kts late tonight and Sunday.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM CST Sunday for ILZ040-047>052-061>063-
066>068-071>073.
High Wind Warning from 2 AM to 6 PM CST Sunday for ILZ027>031-
036>038-041>046-053>057.
&&
$$
UPDATE...07
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...07
Area Forecast Discussion
National Weather Service Louisville KY
939 PM EST Sat Feb 23 2019
.Forecast Update...
Issued at 930 PM EST Sat Feb 23 2019
Rain and embedded thunderstorms continue tracking NE across central
KY at this time. The heaviest rain continues to be across south-
central KY where Flash Flood Warnings exist for the next couple/few
hours. High rain rates exist in the strongest cells. Be vigilant if
driving - Turn Around, Don`t Drown if flooded roads are encountered.
Steady rain will end after this current shield moves out over the
next hour or two. Nevertheless, areal flooding will continue for a
time after the rain ends. Thus, will keep the current Flood Watch as
is for the time being, with its expiration at 06z. Also, with the
cold front still several hours to our west, there could be isolated
additional showers develop behind this rain shield. There are
several showers now just east of STL, but the latest HRRR keeps
these to our north over the next couple hours. So, any new cells
in our area should be isolated.
...VERY WINDY LATE TONIGHT AND ESPECIALLY SUNDAY...
Want to take this time to again reiterate the real wind hazard for
very late tonight and especially Sunday. Behind the cold frontal
passage toward morning, surface winds first from the SW then from
the W on Sunday will really increase. Our current Wind Advisory
begins at 09z. We expect sustained winds of 20-30 mph with frequent
gusts of 40-50 mph. Could see isolated gusts over 50 mph. Also of
acute interest is that these winds will have numerous hours of
longevity, i.e., all day Sunday. This will create a real and
impactful hazard. With grounds saturated, these winds could uproot
some trees and at least bring limbs down. Some power outages are
likely as well. People driving on north-south-oriented interstates
should use much caution on Sunday due to a stiff cross-wind. Be
aware of the wind on Sunday and exercise caution and good judgment!
&&
.Mesoscale Update...
Issued at 820 PM EST Sat Feb 23 2019
Area of rain continues to propagate NE across central KY, with
additional numerous shower development on west side of the steady
rain, as high res models have indicated this evening. Latest KLVX
and KOHX radar showing some stronger cores/cells entering or moving
toward our SW counties (around and SW of BWG). Latest meso
environment continues to show very strong low-level shear across the
area, but effective shear values are a little less given slight
elevated nature of the stronger cores. There is a narrow axis of
weak CAPE on the western side of the rain, which will move east
through the evening, albeit diminish. Any chance for an isolated
severe cell would be mainly across our southern counties this
evening.
Continue to be more worried about flash flooding this evening,
particularly over south-central KY given prior rains earlier this
evening and afternoon, and the increasing trend in reflectivity
values over our SW as the low-level jet and lifting increase ahead
of the cold front. Expect brief but intense rainfall rates with
these cores, which could easily lead to local flash flooding.
Use caution if driving! Remember, Turn Around, Don`t Drown.
&&
.Short Term...(This evening through Sunday)
Issued at 305 PM EST Sat Feb 23 2019
...Flash Flooding and Severe Storm Risk through Late Evening...
...Windy Sunday...
A complex of showers and storms over western KY and central and
western portions of TN will continue to spread northeast over
central KY/southern Indiana late this afternoon. Soundings indicate
an elevated environment ahead of this complex due to the presence of
a strong LLJ. Because of this, not expecting any immediate severe
risk through early evening. However, an isolated t-storm may
produce small hail ahead of the main storm complex. The main threat
with this afternoon/early evening round of convection will be heavy
rain and flooding. With excellent upper/lower jet support and
higher precipitable water values entering the region, expect
efficient rain producers and moderate to heavy rainfall rates
especially in t-storms. While the Flash Flood Watch still looks to
be in good shape highlighting the area at most risk, south central
KY is especially a concern as they received up to an 1" of rain
already this morning.
The next round of showers/storms will come mid to late evening
primarily between 0-6Z tonight. We`ll enter a more sfc based
environment after the first storm complex moves northeast through
portions of the region. A line or broken line of showers/storms is
expected to develop just ahead of the cold front and push through
mid to late evening. High-res models still show a thin line of
SBCAPE mainly crossing south central KY later this evening. Also,
favorable wind fields will support rotating cellular structures.
southern KY will be the focus for strong to severe storms containing
damaging winds and potentially an isolated tornado. In addition,
the flash flood threat will continue area wide. All of the
showers/storms should exit the region by around midnight.
Behind the cold front, winds will shift to the west-southwest and
become very gusty in a tight pressure gradient on the back side of
the low pressure system. Wind gusts in excess of 35 mph will be
likely late tonight through Sunday area-wide. Wind gusts of 40-45
mph will be most likely over southern Indiana and portions of north
central KY so a Wind Advisory will be issued for that area.
Temperatures will fall into the 40s tonight behind the cold front
and top out in the mid 40s to lower 50s for Sunday highs.
.Long Term...(Sunday night through Saturday)
Issued at 315 PM EST Sat Feb 23 2019
Sunday Night - Wednesday...
Expansive surface high pressure will center of the northern Plains
and then into the Great Lakes region during the early to mid week
time frame. Meanwhile, dry and zonal flow will dominate the upper
pattern into mid week. The combination of these two features will
keep us dry at least through the first part of Wednesday. High
temperatures should run mostly in the mid and upper 40s for highs
across southern IN and central KY. Southern KY will likely reach the
low 50s each day. Lows are expected to be in the 20s Sunday/Monday
night, and then warm to the low and mid 30s for Tuesday night. These
temperatures are at or just below normal for this time of year.
Wednesday Night - Saturday...
Zonal flow is expected to persist over the area through the late
week and into the weekend time frame. However, there will be several
weak disturbances passing through the upper flow that could bring
some precipitation chances. See no reason to change this statement
from the previous forecast...
Low-confidence forecast for the late week and early weekend time
frame as the models diverge. Zonal pattern makes it difficult to
time the weak ripples crossing the area, so for now will go with a
fairly broad-brush 20-30 POP for the latter half of the week.
Whenever precip does fall, it will be scattered and light. Temp
forecast is near normal, which could result in precip type
questions. However it`s worth noting that the colder Euro solution
is also a dry solution, while the GFS has warmer temps to go with
its precip chances. In light of that, the chances for wintry weather
are actually quite low.
&&
.Aviation...(00Z TAF Issuance)
Updated at 700 PM EST Sat Feb 23 2019
Large shield of rain and a few embedded thunderstorms continue to
move NE across central KY early this evening, producing MVFR vsbys
and at times IFR vsbys in heavy rain. Additional showers and a few
storms are expected behind this main area of rain through late this
evening before coming to an end. Ceilings have varied from VFR to
MVFR so far, and model cross-sections suggest some IFR ceilings
could occur at times for the next several hours before a cold front
pushes across the region later tonight.
Current surface winds are from the SE and will slowly increase and
switch to S this evening. Winds 2-3 kft above the ground will
increase to around 50-55 kts, so have included low-level wind shear
for a few hours this evening at the TAF sites.
Late tonight and on Sunday, surface winds will become very gusty,
first from the SW then from the W on Sunday. Expect sustained winds
of 20-25 kts with gusts of 35-40 kts on the back side of strong low
pressure pushing into the Great Lakes area.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Wind Advisory from 4 AM EST /3 AM CST/ to 7 PM EST /6 PM CST/
Sunday for INZ076>079-083-084-089>092.
KY...Wind Advisory from 4 AM EST /3 AM CST/ to 7 PM EST /6 PM CST/
Sunday for KYZ023>043-045>049-053>057-066-067.
Flash Flood Watch until 1 AM EST /midnight CST/ Sunday for
KYZ023>031-033>043-045>049-053>057-061>067-070>078-081-082.
&&
$$
Mesoscale....TWF
Update.......TWF
Short Term...AMS
Long Term....BJS
Aviation.....TWF
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
921 PM CST Sat Feb 23 2019
.UPDATE...
851 PM CST
There continue to be several forecast concerns and challenges
this evening. They include:
1.) Showers and storms moving across the area this evening, with
some small hail potential.
2.) Fog this evening, becoming dense for a period, before
improving after midnight.
3.) Strong winds developing towards daybreak Sunday and continuing
during the day.
Showers and a few thunderstorms continue to shift north-
northeastward across the area this evening. Some of the strongest
storms have produced small hail to the size of peas, or slightly
larger. This activity is likely to wane by midnight as the strong
mid-level impulse pushes overhead.
The surface low is now moving northeastward over east central
Iowa, while the associated surface boundary is shifting northward
into my southern CWA. With the approach of this warm front is
coming the strong northward push of higher dew point air to from
the south. As these mid 40s to near 50 degree dew points continue
to surge northward into the cooler air over far northern IL, there
is likely to be some degraded visibility in fog over the area
through the rest of the evening. There will likely be areas of
dense fog, at times, with visibilities falling to around one
quarter mile. We have tossed around the idea of issuing a dense
fog advisory, similar to our neighbors to the west and north.
However, thus far the lowest visibilities have not been
widespread. Also, with the fog expected to improve quickly by, or
shortly after midnight with the south-southwestward wind shift and
passage of the surface low, we have opted to hold off the
issuance at this time.
The main concern following the passage of the deepening low
tonight is the onset of strong westerly winds very late tonight
and continuing through the day Sunday. Very impressive three hour
pressure rises following the passage of the cold front have been
up to around 10 mb over parts of southeastern KS this evening.
This is to helping to drive some impressive winds with the cold
frontal passage. Directly following the front, areas over
southwestern MO have reported winds gusts of 40-45 KT.
Considering that these strong pressure rises are expected to
strengthen some as they spread northeastward over the area by
daybreak Sunday, we are likely to experience winds gusting to
this magnitude, with 50+ kt winds also likely at times, especially
during the morning. For this reason, no changes are planned to
the going high wind warning. Expect strong winds of 40-45 kt to
continue through the afternoon and evening, before winds abate
Sunday night.
Scattered snow showers are also expected at times during the
morning. While not much snow is expected, the combination of the
snow showers and wind gusts to 50 kt could make for some periods
of reduced visibilities. However, by far the winds will be the
primary hazard for the day.
KJB
&&
.SHORT TERM...
255 PM CST
Through Tonight...
A plethora of weather over the area the next 24 hours as can be
common when a deep low pressure center passes directly over an
area during a transition season. For tonight, the overall threat
of high impact weather for most of the night looks lower, but
several things to keep an eye on. A High Wind Warning goes into
effect at 3 a.m., with strong winds advancing from west to east
across the area during the pre-dawn/sunrise period.
The elevated warm sector continues to overspread the area, with a
somewhat diffuse but assisting coupled upper jet providing
forcing for areas of showers. The showers have been frequent
enough to allow churning/mixing of the lowest levels and prevent
much dense fog along an otherwise favorable warm frontal trough
over northern/central Illinois. These arcs of showers should
continue to lift over the area through the evening, with pockets
of drizzle in-between. With stronger forcing overspreading during
the evening and MUCAPE values of 300-700 J/kg, would expect some
deeper updrafts for February with isolated to scattered storms.
Convective-allowing models such as the HRRR have indicated this
throughout today. A few could have small hail and some will have
brief heavy rain that may allow for spotty nuisance ponding on
roads. As for anything lower-level based later this evening, this
continues to look like a very limited possibility. The surface
triple point will struggle to have an effective air mass in the
immediate low-levels with it, given surface temperatures peaking
in the mid 50s in the southeast CWA this evening and robust
convection in the upstream flow. Will still be something to keep
an eye on for the mid-evening time given the synoptic pattern and
dynamics, and there could still be a few more robust storms in the
southeast CWA, but the trend has been favorable to keep an
isolated wind / brief tornado threat south.
With the upper wave becoming increasingly negatively tiled this
evening, the surface low will deepen to below 990 mb by midnight.
The dry slot will overspread the CWA near that time and winds will
shift southwesterly in direction. The commahead structure of the
cyclone in this mature phase should continue to become more
defined and grow, and given the forecast path of the 700mb low
and wraparound moisture and deformation near that level, would
expect at least the northern half of the CWA to be under this
late. So have precipitation chances increasing back into the
western/northern CWA late tonight, with a propensity to become
more snow showers near daybreak.
MTF
&&
.LONG TERM...
244 PM CST
Sunday through Saturday...
A very active weather pattern is still expected for much of the long
term forecast period. Multiple concerns are expected, including,
strong winds and scattered snow showers on Sunday and couple periods
of rain/snow mid to late next week.
By early Sunday morning, the deepening sfc low should be lifting
newd through the Upper Great Lakes and the strong cold front will
have pushed to the east of the area. Strong pressure rises of 10-12
mb per 3 hrs will be in place across the CWA as the deepening sfc
low lifts away from the region and strong high pressure builds into
the Central Plains. In combination with very strong cold advection
following the passage of the cold front and winds at the top of the
boundary layer of 50-60 kt, rapidly strengthening west winds should
be under way shortly before day break, reaching sustained speeds up
to 40 mph with gusts up to 60 mph. The strong west winds will
likely persist through much of the day and a High Wind Warning has
been issued for early Sunday morning until early Sunday evening.
Some scattered wrap-around snow showers will also be possible during
the morning hours. While little or no accumulation is expected, the
strong winds combined with the scattered snow showers may produce
short period of white-out conditions.
With persistent cold advection setting up following the fropa,
temperatures are expected to fall through the day. Temperatures
should start out Sunday morning in the lower 30s west of the Fox
Valley and I-55 corridor, with mid to upper 30s to the east. By
Sunday evening temperatures should be dropping in to the middle
teens in the Rockford area and the lower 20s south and east of a
Chicago to Peru line. The cold advection will continue overnight,
driving temperatures down into the lower single digits above zero over
the nwrn portions of the CWA to the lower teens for the southeast
sections. While winds are expected to gradually diminish
overnight, speeds should still be around 15 to 25 mph, driving wind
chill readings as low as -10 to -20 F north of a Chicago to Peru
line and -5 to -10 F to the south of that line.
For the remainder of Monday until the end of the period, the upper
level pattern will transition from high amplitude to a more zonal
flow pattern. Weak embedded shortwaves rippling through fast flow
aloft will supporting occasional periods of light snow. However,
given the inherent uncertainty to the timing of short waves tracking
through fast zonal flow aloft, associated PoPs and potential
accumulations are a very low confidence forecast. Following the
cold Monday with highs in the teens northwest to middle 20s
southeast, temperatures for the remainder of the period should be
below seasonal normals.
&&
.AVIATION...
For the 00Z TAFs...
604 PM...Multiple forecast concerns including...
Fog/low clouds this evening.
Chance of thunderstorms mid/late this evening.
Southeast to Southwest wind shift around midnight.
Very strong winds/gusts developing by sunrise Sunday.
Snow showers/snow squalls Sunday morning.
An area of light rain is moving across the terminals early this
evening with prevailing visibilities generally in the 1-2sm range.
Once this activity ends...there will be a brief period were vis
may drop below 1sm. Additional showers and possibly isolated
thunderstorms are then expected to develop during the mid evening
which should help improve any lower visibilities. In addition...
low level wind shear will steadily increase over the next few
hours and this may mix the low levels just enough to prevent any
significant/dense fog. Confidence is low for thunder coverage this
evening and maintained vicinity mention for a 2-3 hour period. By
late evening/early morning...there should be a break in the
precipitation as the area is dry slotted. This should allow cigs
and vis to improve to at least mvfr...possibly vfr.
Easterly winds will become southeasterly this evening with gusts
to 20kts developing. These winds will continue shifting to the
southwest around/shortly after midnight with gusts increasing into
the mid 20kt range. Another period of rain showers will move
across the area during the overnight hours with low mvfr and
possibly brief ifr cigs moving back across the terminals. This
precipitation may mix with light snow or possibly change to all
light snow prior to sunrise.
As the surface low pressure lifts northeast across eastern WI
early Sunday morning...a strong cold front will move across the
terminals shifting winds westerly. Strong pressure rises combined
with the deepening low and a tightening gradient will result in
prevailing wind speeds in the 30-35kt range with gusts into the
45-50kt range. There remains some uncertainty regarding how long
the strongest wind gusts will prevail and while gusts to 40-45kts
are expected through late Sunday afternoon...the period of gusts
to 50kts may end up being shorter than currently indicated. As
these stronger winds arrive...there will likely be a period of
scattered snow showers that should end by mid morning and have
included this potential as tempo mention. cms
&&
.MARINE...
258 PM CST
Following the passage of a strong cold front late tonight, winds
over Lake Michigan are expected to shift to westerly and rapidly
strengthen. Expect a short period of Gale Force winds during the
early morning hours should increase to Storm Force by late morning.
Storm Force gusts will remain possible until early Sunday evening.
therefore, the portion of the Gale Warning for the IL/IN nearshore
waters from 09z Sunday until 00z Monday has been upgraded to a Storm
Warning. After the end of Storm force gust potential, winds should
still be Gale Force until early Monday morning. With very cold air
filtering in behind the cold front, a period of moderate to heavy
freezing spray will be likely from Sunday afternoon through Monday
afternoon. Given some uncertainty to the duration of heavy freezing
spray, will hold off on issuing a Heavy Freezing Spray Warning for
the nearshore waters at this time.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...High Wind Warning...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-
ILZ023-ILZ032-ILZ033-ILZ039...3 AM Sunday to 6 PM Sunday.
IN...High Wind Warning...INZ001-INZ002-INZ010-INZ011-INZ019...3 AM
Sunday to 6 PM Sunday.
LM...Dense Fog Advisory...nearshore waters
until 1 AM Sunday.
Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...3 AM
Sunday to 8 AM Sunday.
Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...10 PM
Sunday to 3 AM Monday.
Storm Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...8 AM
Sunday to 10 PM Sunday.
&&
$$
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Area Forecast Discussion
National Weather Service Paducah KY
929 PM CST Sat Feb 23 2019
.UPDATE...
Issued at 929 PM CST Sat Feb 23 2019
Cancelled the Flash Flood Watch for the remainder of western
Kentucky and updated the forecast to reflect this and reduction
in rain chances for the remainder of the evening. Radar indicates
widely scattered showers across southwest Illinois mid evening,
so maintained a slight chance across the northern half of southern
Illinois, southwest Indiana, and the Kentucky Pennyrile through
the rest of the evening.
Also adjusted wind and wind gust grids with latest CONSShort,
NAMNest, and HRRR guidance. Wind gusts will likely gust as high as
40 to 50 mph across much of the region for a 2 to 3 hour window
immediately behind the cold front between midnight and 6 AM. The
strongest winds will start across the Missouri Ozarks just before
midnight, reaching I-57 and the Paducah area 1 to 2 AM, then
Evansville and Hopkinsville by 3 AM. Winds will remain gusty
through the night and into Sunday, but the strongest winds are
expected in the wake of the front overnight. A few gusts may
exceed 50 mph, especially across the northern tier of southern
Illinois into southwest Indiana.
Otherwise, remainder of forecast is on track and largely
unchanged from prior.
UPDATE Issued at 647 PM CST Sat Feb 23 2019
Updated the forecast to raise wind speeds/gusts overnight and
extend the Wind Advisory to include the entire forecast area. The
advisory still runs from midnight until noon across the northern
half of the area. The southern half runs from midnight until 6 AM.
Available short term model guidance, including the NAMNest, HRRR,
and even blended data suggests the likelihood of wind gusts of 40
to 50 mph in the wake of a cold front after midnight tonight.
Steep lapse rates within the lowest 3-5 kft will promote efficient
mixing of very strong winds aloft to the surface. In this layer,
NAM and GFS forecast soundings indicate winds in excess of 45-50
knots, and much of this momentum will likely translate to the
surface.
The peak period of strongest winds is expected from midnight
until 6 AM across the entire region. Strong gradient winds will
continue through at least the morning hours across the northern
half of the area.
UPDATE Issued at 550 PM CST Sat Feb 23 2019
The AVIATION section has been updated for the 00Z TAF issuance.
UPDATE Issued at 349 PM CST Sat Feb 23 2019
Cancelled a portion of the Flash Flood Watch, northwest of a
Murray to Greenville KY line.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 257 PM CST Sat Feb 23 2019
A very strong storm system lifting northeast into the
Midwest and Great Lakes region tonight will drag a cold front
through the region. Most of the precip wit the system should lie
along a pre-frontal trof ahead of the cold front, so only far
eastern counties will see any shower chances linger into the
evening. Bigger story will lie with the strong and gusty southwest
to westerly winds behind the front. Will continue wind advisory
over about the north half of the forecast region, where gusts
could exceed 40 mph...especially after midnight.
Looking for a breezy but sunny day on Sunday as surface high
pressure drops southeast into the northern Plains and Midwest.
The good news for many is that this high pressure system will
bring us an extended period of dry weather right into mid week,
with seasonably cool conditions.
.LONG TERM...(Wednesday through Saturday)
Issued at 257 PM CST Sat Feb 23 2019
Another cold front will take aim on the forecast area Wednesday.
However, this front looks to be moisture starved with only weak
low level moisture return and very little mid/upper level support.
In fact, H50 flow should be nearly zonal at that time. Another
seasonably chilly high pressure system will move southeast into
the Midwest and Great lakes regions Thursday and Friday. Though
pesky ripples of energy aloft could create some very light rain or
wintry precip during that time, at this time it is looking as
though impacts would be minimal to nil.
Yet another in a series of cold front is expected to push
southeast through the region Friday. Once again, not looking for a
great deal of moisture or lift with the front, so will keep precip
chances pretty low at this time. However, a much stronger
surface high is expected to push southeast into the Plains as we
head into the weekend, bringing another shot of cold Canadian air
with it.
In a nutshell, no Spring conditions yet in sight. Should be an
extended period featuring multiple shots of Canadian air.
&&
.AVIATION...
Issued at 550 PM CST Sat Feb 23 2019
It appears that IFR ceilings will be pushed north of KMVN and KEVV
to begin the period, leaving only a chance of a few hours of MVFR
ceilings moving northeast across most sites later this evening.
Showers will impact KOWB for the next hour or so, but a period or
two of MVFR visibility is the main impact.
Another band of lower clouds, likely MVFR in the north and northeast,
but possibly VFR in the southwest, will push eastward through the
region in the 08Z-14Z time frame. Clear skies are then expected
for the remainder of the day. Winds will veer through the evening
to southwest throughout the region with gusts 20-30kts possible.
Overnight and through the day, west northwest winds will gust over
30kts in most places with 35-40kts possible across the north.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Wind Advisory until 6 AM CST Sunday for ILZ088>094.
Wind Advisory until noon CST Sunday for ILZ075>078-080>087.
MO...Wind Advisory until 6 AM CST Sunday for MOZ086-087-100-107>112-
114.
Wind Advisory until noon CST Sunday for MOZ076.
IN...Wind Advisory until noon CST Sunday for INZ081-082-085>088.
KY...Wind Advisory until 6 AM CST Sunday for KYZ001>013-015>017-021-
022.
Wind Advisory until noon CST Sunday for KYZ014-018>020.
&&
$$
UPDATE...RJP
SHORT TERM...GM
LONG TERM...GM
AVIATION...DRS