Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/13/20
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1035 PM EDT Sun Apr 12 2020
.SYNOPSIS...
Rain will overspread the region during the early
morning, as an intense storm system will impact eastern New York and
western New England into Monday night. The storm will bring strong
to damaging winds to the area along with moderate to heavy rains and
a chance for thunderstorms. In the wake of the system, it will be
cooler for the rest of the week with below normal temperature for
mid April.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 1030 pm EDT...The clouds continue to thicker and lower
ahead of a warm front and the lead short-wave in the deep
southwest flow ahead of a potent mid level short-wave trough
lifting out of the lower MS River Valley, and the Southeast.
A region of upper level diffluence has set up over the
Northeast ahead of the potent digging H500 trough depicted on
the water vapor imagery. We continued to slow the PoPS down
slightly based on current radar returns to the south and the
latest 00Z 3-km HRRR trends. We have now gone with a dry
forecast prior to 06Z/MON for most of the region. The 00Z KALY
soundings is very dry below 700 hPa and it will take a little
time to moisten the low-levels.
The isentropic lift increases quickly as the potent H925/850
LLJ impacts the region between 06Z-12Z/MON. PoPs were increased
to categorical values between 08Z-10Z.
The rain will come down moderate to heavy at times by daybreak.
Southerly winds will increase to 10 to 20 mph with some gusts in
the 25-35+ mph range by sunrise. Lows will be quite mild in the
40s to lower 50s across the region.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
An intense low pressure system will strong to damaging winds to the
area Monday into Monday night along with a moderate to heavy
rainfall and chances for thunderstorms.
High Wind Warning has been issued for northwestern Connecticut and
western Massachusetts for 6 am to 6 pm Monday for southerly
winds.
Wind Advisory has been issued for Warren and Washington
Counties, the Taconics, Mid Hudson Valley and southern Vermont
for 6 am and 6 pm Monday for southerly winds.
Wind Advisory has been issued for Western Adirondacks, Mohawk
Valley, Capital District, Saratoga region, Schoharie Valley,
Helderbergs and eastern Catskills for 6 am to 11 pm Monday for
southerly winds during the day and westerly winds in the
evening.
Anomalies continue to be extremely impressive with 850mb/925mb
winds +4-6 SD, 850mb moisture flux 6+ SD, PWAT +2-3 SD,
500H/700H -3-4SD and surface pressure -4-5SD.
Guidance continues to have a 60 to 90 knots 925mb jet that
passes over the NWS OKX and much of the NWS BOX forecast areas
during the day morning.
Focus for heaviest rain is during the morning hours with the
850mb jet (50 to 80 knots) moving through ahead the system warm
front. Have locally heavy rainfall possible in the morning
mentioned in the forecast.
Focus for thunderstorm threat is during the afternoon in the
warm sector. With warm air advection will have inversion in
place. An instability will be meager. The Storm Prediction
Center has maintained general thunderstorm threat across the
northeastern two-thirds of the forecast area and a marginal risk
for severe across the southwest third where there is a better
chance for some instability to develop.
Activity winds down quickly in the evening. Winds will finally
back off overnight will remain brisk and gusty across much of
the area.
With a mild start to the day highs are expected to be in the mid
50s to mid 60s. With the passage of the system cold air
advection will cause temperatures to drop around 25 degrees with
lows in the 30s to lower 40s with some 20s in the western
Adirondacks.
Colder and more seasonable Tuesday with a longwave trough
across the CONUS with short waves moving through the flow. A
weak wave will pas to our well to our south Tuesday and Tuesday
night with slight chances for showers grazing the southern most
reaches of the forecast area. Colder Tuesday night with lows in
the mid 20s to upper 30s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The main weather headlines during the extended includes 1) the
influence of an amplified mean upper trough that will yield cooler
than normal temp anomalies, if not all of the period, 2) multiple
weak mid-level disturbances that will bring slight or low chances
for some isolated to scattered rain/snow showers to the region
Wednesday through Thursday, 3) a stronger impulse that we continue
to monitor that has the potential to bring a more widespread
threat/chance for precipitation Friday aftn/eve. into Saturday, and
4) the potential for moderating temperatures returning closer to
normal levels next weekend.
Wednesday through Thursday:
Forecast models continue to advertise multiple weak mid-level
impulses that will track along the edge of an attendant upper trough
overhead. This combined with some diurnal surface heating, lake
enhanced and/or orographic (upsloping) effects will help in
aiding/triggering some cloud development and thus the potential for
scattered rain/snow showers. Given the limited amount of available
moisture, significant accumulations of any rain/snow showers are not
expected. The higher terrain areas are most favored to see snow
showers with light accums of a coating to less than a half inch.
Friday through Sunday:
Attention then turns to a strong, more vigorous disturbance that
will dig into the Pacific Northwest/Northern Rockies midweek before
ejecting out of the central U.S. and towards the eastern U.S. late
week into the weekend (second half of Friday into Saturday).
Forecast models (particularly the GFS and Canadian-NH models) have
now come on board with the 00Z ECMWF with this general idea. Given
that we`re still 5 days out, it`s still rather early in terms of
pinpointing the precise track, location, and intensity of this next
storm system. That said, this storm system so far looks to be the
most promising and should this storm system track towards our area,
it has the potential to bring a greater, more widespread chance for
precipitation to the region. Stay tuned for more details as things
further get ironed out. Cloud coverage through Saturday will range
partly to mostly cloudy. Weak riding will build in late Saturday
into Sunday before the next short-wave arrives.
Given that the large scale pattern will be highly amplified early in
the period before relaxing slightly later in the period,
temperatures will start off the period cooler than normal before
moderating to near normal levels late in the period. Wednesday
through Friday, we will see high temperatures in the 40s to near 50
degrees with some cooler temps in the mid and upper 30s over mtns.
On Saturday, high temperatures will be in the 40s to lower 50s and
on Sunday well into the 50s and 40s over the mtns. Overnight low
temperatures will generally run from the 20s into the lower 30s
through the extended. Given that normal high temperatures will run
58-60 degrees during this period, temp anomalies will run 7-9
degrees below average Wednesday through Saturday, and near normal
levels on Sunday.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Clouds will thicken and lower early tonight, and then rain will
overspread the region after midnight, as a warm front
associated with a strong low pressure moving northeast from the
lower and central MS River Valley impacts the area. The low
pressure system will track into the central Great Lakes Region,
as a cold front will move across the region late tomorrow
afternoon into the early evening.
Mid level clouds will increase and lower between 03Z-06Z/MON at
KGFL/KALB/KPOU/KPSF with an increasing southerly flow ahead of
the potent storms system. Initially, light rain will overspread
the terminals, but expect the rainfall to increase between 06Z-
10Z/MON, as cigs/vsbys falling into the MVFR and spotty IFR
range. The best chance for widespread IFR conditions looks like
late Monday morning into the early to mid pm with the cyclone
reaching the OH Valley. The rain will become occasionally
moderate to heavy, as a strong low-level jet focuses the
rainfall. Expect the rain to continue into the pm with a brief
warm sector, where cigs may eventually rise back to low MVFR
levels, but there is a chance some thunderstorms may break out,
and we placed a PROB30 for thunderstorms at all the TAF sites
especially between 19Z-23Z/SUN. Conditions may lower to IFR
levels in the thunderstorms.
Low level wind shear will be dominate starting around 04Z-07Z/
MON from south to north, as the 2 kft AGl winds increase to
40-60 kts. We kept the wind shear going the duration of the TAF
cycle at KGFL...removed the groups between 19Z-20Z/MON at
KPOU/KALB/KPSF. The strong low-level jet will begin to weaken
in the early to mid afternoon, but the cold front will be
approaching.
The sfc winds will be south to southeast at 7-15 kt overnight
with gusts around 20-25 kt developing especially at
KALB/KPOU/KPSF between 08Z-12Z/MON. The winds will become
south to southwest and increase to 14-24 kt with gusts 25-38
kts in late morning into the afternoon.
Outlook...
Monday Night: High Operational Impact. Very Windy. Slight
Chance of SHRA.
Tuesday: Low Operational Impact. Breezy.
Tuesday Night: Low Operational Impact. NO SIG WX.
Wednesday: Low Operational Impact. Slight Chance of SHRA.
Wednesday Night: Low Operational Impact. NO SIG WX.
Thursday: Low Operational Impact. Slight Chance of SHRA...SHSN.
Thursday Night: Low Operational Impact. NO SIG WX.
Friday: Moderate Operational Impact. Chance of SHRA.
&&
.FIRE WEATHER...
An intense storm system will impact the region late tonight into
Monday night bringing strong to damaging winds to the area
along with moderate to heavy rains and chances for
thunderstorms. In the wake of the system, it will be cooler for
the rest of the week with below normal temperature for mid
April.
&&
.HYDROLOGY...
A widespread moderate to heavy rainfall will occur late tonight
through Monday as an intense low pressure system impacts the region.
The Weather Prediction Center has maintained a marginal risk for
excessive rainfall for areas to the south and east of the Capital
District for Monday. Expecting 1 to 2 inches of rainfall across this
area with locally higher amounts across portions of the eastern
Catskill. One to 2 inches is also expected across portions of the
southern Adirondacks and upper Hudson Valley with up to an inch for
the Mohawk and Schoharie Valleys and across the Capital District.
Localized higher amounts are possible where thunderstorms occur.
Urban and poor draining flooding will be possible. At this time,
only Sacandaga River at Hope (Monday evening) and the West Canada at
Hinckley (Tuesday) are expected to exceed flood stage otherwise
river flooding is not expected.
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...High Wind Warning from 6 AM to 6 PM EDT Monday for CTZ001-013.
NY...Wind Advisory from 6 AM to 11 PM EDT Monday for NYZ032-033-
038>041-047>053-058-063-082.
Wind Advisory from 6 AM to 6 PM EDT Monday for NYZ042-043-054-
059>061-064>066-083-084.
MA...High Wind Warning from 6 AM to 6 PM EDT Monday for MAZ001-025.
VT...Wind Advisory from 6 AM to 6 PM EDT Monday for VTZ013>015.
&&
$$
SYNOPSIS...IAA/Wasula
NEAR TERM...Wasula
SHORT TERM...IAA
LONG TERM...Evbuoma/Wasula
AVIATION...Wasula
FIRE WEATHER...IAA
HYDROLOGY...IAA/BGM
Area Forecast Discussion
National Weather Service Bismarck ND
1001 PM CDT Sun Apr 12 2020
.UPDATE...
Issued at 937 PM CDT Sun Apr 12 2020
Latest radar imagery shows snow showers from just south of Minot
extending southwest to Garrison, Hazen Glen Ullin and Dickinson.
Snow showers also extend back west through Watford City, Grassy
Butte and Beach. Snow showers are now winding down in Williston.
The 00 UTC RAP forecast sounding for Bismarck shows strong omega
within the DGZ centered around 07 UTC. 1 UTC RAP analysis also
shows a bullseye of very steep lapse rates centered around
Killdeer and Dickinson at 03 UTC, and propagating to just west of
Bismarck at 07 UTC. then southeast to around Ashley by 10 UTC.
This is congruent with a band of low to mid level FG forcing that
tracks from New Town to Bismarck, then Ashley during the same
timeframe. And at times areas of negative EPV in the 800 to 850 mb
layer. The HRRR is not exactly the same as the RAP but similar.
Both show a couple of enhanced bands of heavier snow. One from
around Watford City south and east into Dunn and Stark counties,
and another from around New Town, south and east along Lake
Sakakawea, to around Bismarck. When we say heavier snow we are
talking 1 to 2 inches, and maybe a locally higher report or two,
compared to a dusting to maybe a half inch. So overall, not
terribly impactful, unless you`re driving through a heavy snow
shower late tonight into early Monday. Also, with the very cold
temperatures, normally wet roads this time of year may be icy
tonight into Monday morning. This was the case earlier this
evening. Wet roads around Williston are now Scattered ice based on
the latest road report. With lows down into the teens tonight,
expect some slippery and possibly partially snow covered roads for
the morning commute.
Used a blend of time lagged rap/hrrr with Official for the
forecast pops through the early morning on Monday. Updated text
products out shortly.
UPDATE Issued at 636 PM CDT Sun Apr 12 2020
A quick update for pops. Latest blend of models brings area of
snow showers currently around Williston, south and east to near
Bismarck/Mandan around Midnight. Occasional moderate to at times
heavy snow showers in the Williston area has resulted in a
quarter to a half inch of accumulation on grassy and elevated
surfaces.
UPDATE Issued at 459 PM CDT Sun Apr 12 2020
Isolated snow showers have developed pretty much across the
forecast area. Updated pops to reflect this. Currently more
numerous snow showers are located across the northwest and north
central and carrying some higher pops here, especially for the
northwest. The northwest and west central will be the focus for
higher pops into the early evening as the forcing associated with
the shortwave trough mentioned in previous discussion.
&&
.SHORT TERM...(This evening through Monday)
Issued at 243 PM CDT Sun Apr 12 2020
Isolated to scattered snow showers/flurries will continue through
the evening across much of western and central North Dakota as a
weak shortwave pushes through the area.
As a midlevel low closes off tonight over northern Manitoba, a
stronger compact shortwave will rotate around it and into western
North Dakota. This wave can currently be seen on water vapor
satellite imagery along the Saskatchewan/Montana border. The NAM
and GFS are in good agreement that a quick moving band of snow
will accompany this feature tonight into Monday morning from
around Williston to the Bismarck/Mandan area and finally down to
the South Dakota border over the southern James River Valley.
While the area of snow will be relatively small and residence
time underneath will be brief, there is a signal that the
strongest part of the band may exhibit a burst of moderate to
heavy snowfall. Both the NAM and GFS show a deep layer of decent
frontogenetical forcing (when looking at filtered 150km
frontogenesis) ideally collocated with strong upper level
Q-vector divergence (smoothed to cancel out the noise of the field
in higher resolution grids) associated with this band. Further,
very steep midlevel lapse rates will be in place with strong omega
maxing out in the dendritic growth zone. Near negative EPV here
suggests a slantwise instability component. Areas along and around
this narrow band of snow can expect a quick half inch to inch of
snow before all is said and done. A few areas could see slightly
more based on the favorable dynamics forecast to be in place.
The wave will quickly depart early on Monday but another weak wave
will rotate around the parent midlevel low that will have drifted
into Ontario by the afternoon. This weak wave will once again
bring isolated to scattered snow showers across the area through
the evening hours before diminishing. Winds will also remain
breezy to windy out of the northwest through the period.
.LONG TERM...(Monday night through Sunday)
Issued at 243 PM CDT Sun Apr 12 2020
High pressure at the surface builds into the region Monday night,
likely setting the stage for the coldest night of the week, with lows
presently forecast in the teens.
Cool weather will continue through the week, with a slow recovery
in temperatures as flow aloft gradually turns more northwest. The
12z NBM guidance that was used for the official forecast calls
for highs returning to the 50s and possibly even the 60s Friday
through the weekend. However, the 12z GEFS members still show
considerable spread with the deamplification of flow aloft and
resultant amount of warming.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 937 PM CDT Sun Apr 12 2020
Scattered to numerous snow showers from Willisson to around Minot
and Rugby, tapering to isolated to scattered from Dickinson to
Bismarck and Jamestown. Began each TAF with a VCSH, except for
KISN with ongoing snow showers as TAF begins. Expect a decrease in
snow shower over central ND in the next hour or two. We do
anticipate an areas of snow showers spreading from current
location around Williston, southeast to around KBIS by around 05
UTC, then southeast toward South Dakota. This area may brush KDIK
also. TAFS indicate a period of reduced visibilities at KDIK and
KBIS tonight with these snow showers. Diurnally driven snow
showers at KMOT will dissipate quickly this evening, and may
linger at KJMS a bit longer. Generally VFR condition except in
areas of moderate to heavy snow showers. Late tonight expect VFR
conditions after snow shower pass. Northwest wind becomes breezy
again Monday afternoon.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...TWH
Area Forecast Discussion
National Weather Service Boston/Norton MA
1002 PM EDT Sun Apr 12 2020
.SYNOPSIS...
A powerful low will track across the Great Lakes late tonight
and Monday, with heavy showers and scattered thunderstorms
during Monday. Strong to damaging winds will likely impact the
region as well. A cold front will swing through Monday evening,
with improving conditions and diminishing west winds. Dry and
seasonable weather on Tuesday. This is followed by cooler
temperatures mid to late in the week. Several chances for
showers mid to late in the week, but no washouts are expected.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
10 PM Update...
No major changes to the forecast in the latest update. Leading
edge of the rain shield now in the Philadelphia area and moving
steadily northeast. Good model agreement among deterministic
and ensemble guidance for rain to overspread western MA/CT just
after midnight and then into RI and eastern MA around daybreak
(~ 6 am). Southerly flow beginning to increase with 22 kt at MVY
and 26 kt at MQE. Winds will continue to increase overnight
although strong to damaging winds hold off until late Mon
morning and especially Mon afternoon.
Previous discussion...
Clouds will continue to thicken as they push across the region
this evening, thanks to mid level westerly winds in place. In
the meantime, long wave H5 trough will continue to dig across
the Mississippi valley, which will cause the steering winds
aloft to back to the SW. This will bring warm air across the
region through the night so, after fall to the mid and upper 40s
early, readings will rise through the remainder of the night.
Most of the 12Z model suite continue to signal a strong H5
short wave in the SW flow moving toward the central Great Lakes
during the night. Excellent lift also in place, so will see
surface low rapidly deepen overnight. Strong low level jet also
in place on the eastern side of this low, so may see S-SW winds
increase after midnight with gusts up to 25-30 kt toward
daybreak, highest along the S coast, Cape Cod and the islands.
Leading edge of showers will push E, reaching western areas by
around midnight, then shifting across the remainder of the
region overnight.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Monday...
*** Strong to Damaging Winds Likely Monday afternoon ***
*** Low risk of isolated flooding with 2"+ rainfall possible ***
Strong Winds...
12Z NAM model continues to show very strong low level southerly
jet moving across E Mass/RI during Monday, on the order of
90-100 kt at H85, with 50-75 kt winds at H925. Big question will
be whether the low level inversion will break if surface temps
become mild enough to bring the strong winds down.
Model guidance has suggested that wind gusts could reach up to
50 to 60 kt as the low level jet passes prior to the cold front
pushing eastward. Looks like the highest winds will occur from
midday through Monday afternoon especially across central and
eastern areas. May see gusts over 60 kt across the southern near
shore waters. Still uncertain whether these winds will mix down
due to colder air below H925 along the S coast. Will need to
monitor the temperature trends during Monday. If increased
mixing does work in at the surface, could see milder temps than
currently forecast which may allow even stronger winds to mix
down.
However, based on the latest guidance, have upgraded to a High
Wind Warning for all areas except Franklin county, where a Wind
Advisory is in effect from midday on Monday into early Monday
night.
Heavy Rain...
Models continue to signal anomalous moisture plume ahead of the
strong Great Lakes system pushing across the region. PWATs up
to 3 to 4 SD above seasonal normal will move across, highest
across central and western areas. Noting the record rainfall
from the SPC sounding climatology for April 13 is 1.32 inches at
KCHH, with the April max rainfall of 1.55 inches. So, as
mentioned in the previous discussion, could see areas of very
heavy rainfall Monday morning into the afternoon. Current
forecast suggests rainfall of 1 to 1.5 inches, possibly up to
1.7 inches across portions of N CT into W RI. Leaned toward the
WPC guidance for QPF amounts. Some question whether winds may
become a bit more SE across western areas, which could add an
upslope component and locally heavier rainfall across the E
slopes of the Berkshires.
Latest update from WPC still keeps the region in a marginal risk for
excessive rainfall on Monday. At this point, leaned toward the WPC
guidance for QPF amounts on this package. So, will continue to
monitor latest guidance for this potential.
Monday night...
As the strong low pushes NE across western Quebec as it deepens
to a sub 980 hPa low, the trailing cold front will swing across
the region Monday evening. The pressure gradient will relax,
allowing winds to diminish as well. Will see SW winds gusting
up to 40-50 kt across eastern areas early, but will diminish to
20-30 kt by around midnight though some higher gusts may linger
across the higher inland terrain and along the coast a bit
longer.
Leftover showers will quickly shift offshore and weaken Monday
evening. Clouds will also dissipate and shift offshore, so skies
will become mostly clear especially across the interior after
midnight. Expect temps to bottom out in the mid to upper 30s
across the higher terrain to the mid-upper 40s along the coastal
plain.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Highlights...
* Active pattern through the extended with several opportunities
for light precipitation. No washouts expected at this point
in time.
* Temperatures trending downward into the middle of the week.
Rebounding late in the week, but still remaining near to
below normal.
Details...
Tuesday...
A cutoff low will be located by James Bay/western Quebec early on
Tuesday. This feature will rotate northward into northern portions
of Quebec. This will keep New England under cyclonic flow. A weak
mid level ridge will build into the Great Lakes. This will nudge a
surface high into southern New England, which will bring dry and
quiet weather.
Will see westerly flow aloft which will advect colder air into the
region at 925 hPa. This will bring some downsloping across the
region, so have increased high temperatures a bit from the previous
forecast. Nudged temperatures up to the 75th percentile of guidance
as there are questions on how much cloud cover will be in place over
the region. If skies are clearer than currently anticipated then
temperature will need to be bumped up further. High temperatures
will be in the 50s across southern New England. Expect cooler
readings along the eastern slopes of the Berkshires.
Good agreement amongst deterministic guidance for strong mixing.
Lapse rates within the boundary layer are adiabatic roughly up to
1.5 km AGL. Right now have gusts of 15 to 20 kts. Not out of the
question that we tap into gusts of 25 to 35 kts if we can completely
mix down winds at higher elevations within the PBL.
Tuesday Night through Wednesday...
Cyclonic flow persists through this time period. Will see a
shortwave trough embedded within the broader cyclonic flow start out
in the Upper Mississippi River Valley Tuesday night and dig into the
central Great Lakes by Wednesday morning. The trough will then lift
into northern New England late on Wednesday. This feature will
interact with the stalled out front extending from the Carolinas to
well offshore of New England. Expect a broad low to develop and ride
along the front. This will bring chances of rain showers with the
best opportunity for these showers across the South Coast, Cape Cod
and the Islands. Expect slight chances further to the north and
west, but should be dry across central and western MA.
Still good agreement amongst deterministic guidance with the
GFS/ECMWF coming more in line with one another today, whereas the
GEM keeps the front further offshore. Ensemble plumes show
clustering of QPF roughly ranging from roughly a tenth of an inch to
a quarter of an inch with the highest amounts expected over
Nantucket and Marthas Vineyard.
Flow aloft will become west northwesterly and advect colder air into
the region. This will bring cooler readings to the region. Low
temperatures heading into Wednesday will generally be in the 30s.
The only exception is along the coast where lows will be around 40.
High temperatures on Wednesday top out in the 40s across the region.
Wednesday Night through Saturday...
Cyclonic flow persists across southern New England through the rest
of the extended. Confidence in the forecast decreases in this window
as models begin to break down the timing and intensity of waves
sliding through and in addition mass fields are significantly
different from model to model and run to run. Due to the uncertainty
have kept the NBM guidance through this window. Still appears that
any precipitation will be light in nature as shortwaves quickly move
through.
High temperatures will be near to below normal during this timeframe
with readings ranging from the 40s to low 50s. Low temperatures will
be in the 30s.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
02z update ... no major changes. Leading edge of rain shield in
Philadelphia area at 02z will overspread western MA/CT around
05z then into RI and eastern MA by 10z. Southerly winds will
continue to increase overnight with LLWS increasing toward 12z
with WS020/18050. Previous discussion below.
================================================================
Tonight...High confidence
VFR initially at all terminals with ceilings gradually lowering
tonight to MVFR as the lower levels moisten and precipitation
moves in. A very strong low will deepen and lift as it moves
into the central Great Lakes. This will bring low level wind
shear to all terminals overnight as the low level jet
strengthens. Somewhat uncertain if it will be more gusty at
times as RAP, HRRR and NAM Bufkit soundings show things remain
decoupled. Have kept gusts out of the forecast across interior
locations, but kept gusts across coastal locations with the
marine layer nearby. Southerly winds at 10-15 kts increasing to
around 15-20 kts late. Gusts of 25-30kts by 12Z. Low level wind
shear of 40-50 kts tonight.
Monday...High confidence. Some uncertainty on how much/frequent the
higher gusts mix down.
Very strong low level wind shear at all terminals through the
day. Expect values of initially 40-50 kts increasing to 60-80+
kts with the highest values expected along the South Coast of
MA and RI. Very strong southerly winds with increasing gusts.
Speeds of 15-25 kts during the morning increasing to 25-35 kts.
Gusts of 25-30 kts increasing to 35-60 kts with the highest
speeds along the South Coast.
MVFR conditions deteriorating to IFR and there may even be
spots of LIFR especially along the South Coast. Widespread
showers, which may be heavy at times. Tried to time out the
period of heavier shower activity with visibility reductions
down to IFR. Not out of the question there could be periods of
LIFR, but have not included in the latest TAF set. Scattered
thunderstorms moving in late in the morning through the
afternoon. Have not included a mention in the latest forecast as
am uncertain on how widespread the activity will be.
Monday night...High confidence.
Showers end from W-E between 01Z to 05Z. Skies scattering out to
VFR. S winds gusting up to around 50 kt across E coastal
terminals early. Winds then shift to W and diminish overnight,
though may see gusts up to 25-35 kt through around 04Z-06Z along
the coast and across higher terrain.
KBOS Terminal...High confidence in the TAF.
KBDL Terminal...High confidence in the TAF.
Outlook /Tuesday through Friday/...
Tuesday: VFR. Breezy.
Tuesday Night through Wednesday: Mainly VFR, with local MVFR
possible. Slight chance SHRA.
Wednesday Night: Mainly VFR, with local IFR possible. Slight
chance SHSN.
Thursday: Mainly VFR, with areas MVFR possible. Breezy. Slight
chance SHRA.
Thursday Night: VFR. Breezy.
Friday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA.
&&
.MARINE...
*** Storm Warning in effect from Monday afternoon into Monday
evening ***
Tonight...
Rapidly deepening low pressure moves across the central Great
Lakes. S winds increase to 20-30 kt toward daybreak on Monday.
Showers move in from W-E after midnight.
Monday...
Southerly winds continue to quickly increase. Expect winds up to
25-40 kt gusting up to 50-60 kt, highest during the afternoon.
Heavy showers move across, along with scattered thunderstorms.
Poor visibility in areas of fog. Seas build to 18-22 feet,
highest on the southern open waters.
Monday night...
S-SW winds 25-35 kt gusting to 50 kt, highest across the eastern
waters early, will shift to W and diminish. Gusts up to 25-35 kt
linger after midnight, but should drop below small craft toward
daybreak Tuesday. Seas up to 18-20 ft offshore and across the
southern waters early, subsiding to 5 to 8 feet on the eastern
waters and up to 11 ft on the southern outer waters by daybreak
Tuesday.
Outlook /Tuesday through Friday/...
Tuesday: Winds less than 25 kt. Rough seas up to 12 ft.
Tuesday Night: Winds less than 25 kt. Local rough seas. Chance
of rain showers.
Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers.
Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.
Thursday: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers.
Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.
Friday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Chance of rain showers.
&&
.TIDES/COASTAL FLOODING...
Southerly winds will intensify tonight and especially on
Monday. The prolonged period of very strong southerly winds in
combination with the Monday afternoon high tide across the
South Coast and Narragansett Bay will lead to elevated water
levels.
Closely stuck to the Stevens Institute guidance and bumped up
values within Narragansett Bay to more closely match this
guidance. There is a wide envelope per the ensemble guidance in
Providence, RI. Astronomical high tides will be around a MLLW
of 4.2 feet during the afternoon. Expecting around a 2.5 to 3.5
ft surge, which will bring MLLW around 7 ft per Stevens
Institute guidance. Though no coastal flooding is currently
anticipated, this will need to be closely monitored in future
forecast updates.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...High Wind Warning from noon to 7 PM EDT Monday for CTZ002>004.
MA...High Wind Warning from 3 PM to 10 PM EDT Monday for MAZ013-
016>021.
High Wind Warning from 3 PM to 7 PM EDT Monday for MAZ005>007-
014-015.
High Wind Warning from noon to 7 PM EDT Monday for MAZ004-
008>012-026.
High Wind Warning from 4 PM to 10 PM EDT Monday for MAZ022>024.
Wind Advisory from noon to 8 PM EDT Monday for MAZ002-003.
RI...High Wind Warning from 1 PM to 10 PM EDT Monday for RIZ003>008.
High Wind Warning from 1 PM to 7 PM EDT Monday for RIZ001-002.
MARINE...Storm Warning from 3 PM to 10 PM EDT Monday for ANZ231-232-251.
Storm Warning from 2 PM to 10 PM EDT Monday for ANZ233-234-250-
254-255.
Storm Warning from 4 PM to 8 PM EDT Monday for ANZ230.
Storm Warning from 2 PM to 9 PM EDT Monday for ANZ236.
Storm Warning from noon to 10 PM EDT Monday for ANZ235-237-256.
&&
$$
SYNOPSIS...BL/EVT
NEAR TERM...Nocera/BL/EVT
SHORT TERM...EVT
LONG TERM...BL
AVIATION...Nocera/BL/EVT
MARINE...BL/EVT
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service State College PA
1113 PM EDT Sun Apr 12 2020
.SYNOPSIS...
Locally heavy downpours are possible through the night as rain
spreads across the area. Strong, gusty winds will also precede
and occur in the wake of a cold front before subsiding Monday
night. Severe thunderstorms may develop along and ahead of the
sharp cold front as it sweeps through the area from Monday
morning through the mid afternoon. Temperatures will drop
sharply Monday afternoon and evening and trend below average for
the rest of the week.
&&
.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
Rain now flowing northward nicely, but light so far. Everything
is on track.
Prev...
Rain just a little slower moving, most likely due to the drier-
than-expected air in the llvls. Lowered dewpoints in many places
and delayed onset of rain. Elevated instability present later
tonight (before sunrise), so also added mention of thunder to
the southern tier and inch it northward thru 10 AM.
Prev...
Mid level altocu clouds and cirrostratus above will vary in
amount and opacity this afternoon. A nearly east/west band of
higher theta-E air in the 800-700 mb layer was leading to some
light rain falling/spreading NNE from SW PA, while mainly
sprinkles and virga were occurring further east, along and to
the north of the Mason Dixon line
Increasing southerly flow/LLJ will transport 1+ inch PWATs into
central PA tonight. Expect widespread rain to overspread the
area by midnight with locally heavy downpours possible into
early Monday morning. The risk for flooding remains low with
forecast rainfall amounts generally around a 0.50 inch or so
ending 12Z Monday.
Posted a Wind Advisory for late tonight through early Monday
evening for the very strong southerly LLJ that will buffet
mainly the ridge tops with 40 to 45KT gusts, but also create
standing waves of strong wind gusts at the base of the first
wave just to the north of the ridges with strong gap winds too.
As a strong Cfront crosses the region later Monday morning
through mid afternoon, we`ll see a transition to west- southwest
wind gusts at the same speeds for much of the Central Ridge and
Valley Region and Susq Valley, while greater 3 hourly sfc
P-Rises of nearly 10mb and strong CAA across the NW Mtns and
Laurels (Closer to the strong sfc low track across Lake Erie)
will help to create wind gusts as high as 50 kts - warranting a
High Wind Warning there (14Z Mon through 00Z Tue).
&&
.SHORT TERM /8 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
Wind fields aloft really crank up into Monday morning with the
southerly LLJ reaching 70-80kts or +4-5SD above the mean across
the eastern half of the area.
A very strong shear/modest CAPE environment is forecast ahead
of a sharp cold front progged to sweep across CPA between
~14-20Z Monday. Assuming clouds breaks can develop in the wake
of the overnight/early morning WAA rains, a significant risk of
organized severe weather will exist with storms capable of
damaging winds (primary threat) but also an isolated tornado or
two.
SPC has maintained its SLGT risk for Monday, including TOR
Probs of 5% over much of our CWA.
This is further supported by the latest, 18Z RAP that is on the
more aggressive side with a nose of 2.5-3.5M2/S2 EHIs spreading
north to the Central Mtns near KUNV by 15Z Monday, within the
belt of 50-65KT South-SSW winds at 850 mb and about 75-100NM
ahead of the Cfront. MU CAPE within this prefrontal, LLJ
instability max will reach 1500-1800 J/KG during the late
morning through early afternoon hours across the eastern half of
the CWA, and will be associated with the primary threat of
lower-topped, fast moving mini-supercells and bow echoes capable
of the localized/enhanced wind damage and a few tornadoes.
Fixed layer sig tor parameter peaks between 2.5 and 4 acrs the
Scent Mtns through the Lower and Mid Susq valley between 15-18Z
Monday. Plan to have plenty of eyes on the KCCX Dual Pol and
regional 88Ds/TDWRs covering our SE Zones where the greatest
SVR/TOR threat appears to be.
Max temps will likely reach the L70s across the Lower
Susquehanna Valley during the early afternoon and will peak in
the 60s elsewhere.
Temps will fall sharply across the NW half of the CWA and into
the 40s-L50s by late afternoon in the wake of the cold front.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
A brief lull in the weather is expected Monday night into
Tuesday, as the cold front pulls east of the area. A weak
disturbance could brush the region with a bit of light rain or
(becoming more likekly) wet snow Tuesday night into Wednesday as
below normal temperatures continue.
Medium range guidance continues to show an anomalous upper
level trough over the Great Lakes and northeastern CONUS through
the remainder of the week into next weekend, supporting a
continued stretch of below normal temperatures. Another weak
disturbance could bring a bit of light rain or wet snow across
the area Wed night into Thurs, with both the ECMWF and GFS
projecting a more substantial area of low pressure to impact the
region Friday into Friday night with a return of breezy
conditions.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Rain showers will overspread from southwest to northeast
overnight. Prevailing MVFR conditions are expected with the
best possibility of IFR at AOO, UNV, and the southeastern
airfields before daybreak.
Gusty winds out of the south and an approaching cold front will
keep LLWS a threat through the morning on Monday. Potential for
a line of severe thunderstorms accompanying the cold front
between 10A and 2P on Monday. Have attempted to time out cold
front and passage of storms in TAfs.
Strong southerly gradient winds gusting up to 40 kts at times
across the higher terrain and downwind (north) of the ridges
will transition into strong WSW post cold frontal winds Monday
(late morning west and early afternoon east)
Tue-Wed...Increasing chance for rain/snow Tue night-Wed.
Thu...Still a chance of rain and snow showers across
the north and west.
Fri...Rain possible with reduced cigs areawide.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 4 AM to 8 PM EDT Monday for PAZ006-011-012-
018-019-025>028-034-035-037-041-042-045-046-049>053-056-058.
High Wind Warning from 10 AM to 8 PM EDT Monday for PAZ004-005-
010-017-024-033.
Wind Advisory from 4 AM to 10 AM EDT Monday for PAZ004-005-010-
017-024-033.
Wind Advisory from 7 AM to 8 PM EDT Monday for PAZ036-057-059-
063>066.
&&
$$
SYNOPSIS...Dangelo/Lambert
NEAR TERM...Dangelo/Lambert/Steinbugl
SHORT TERM...Steinbugl
LONG TERM...RXR/Evanego
AVIATION...Lambert/Banghoff
Area Forecast Discussion
National Weather Service Peachtree City GA
1000 PM EDT Sun Apr 12 2020
.UPDATE...
Still on track for widespread severe storms during the remainder
of this evening and into the overnight period. Have already seen
some potential tornadic storms across the NW. In addition,
training across these areas is leading to flash flood concerns as
well. Wedge that was aiding in keeping things stable across the
region has all but eroded away now, allowing for the CAPE values
to increase from the south. Atmosphere over most of the area is
now primed for the arrival of main event moving through central
Alabama currently. Straight line winds look to be a major concern
with hatched area and 45 percent contour from SPC now over a large
portion of the area. But also still very concerned with tornado
potential along the line as well with high dewpoint environment
feeding into the line as it progresses east. Grids have all of
this covered exceptionally well with all the severe and tor
verbiage in there along with categorical pops. Will make some
minor changes but overall, these grids will ride.
Deese
&&
.PREV DISCUSSION... /issued 742 PM EDT Sun Apr 12 2020/
PREV DISCUSSION... /issued 332 PM EDT Sun Apr 12 2020/
.INCREASED CONCERN OF SIGNIFICANT SEVERE WEATHER OUTBREAK LATE
TODAY INTO EARLY MONDAY MORNING...
SHORT TERM /Rest of today through Monday Night/...
Things should ramp up quickly here for a significant outbreak of
severe storms (possibly the strongest event in at least the last 2
to 3 years) having the big three main threats of strong long-
track tornadoes, damaging winds, and large hail this afternoon
into the overnight. Much of the western CWA remains in a Moderate
Risk with the rest of the area in an Enhanced, though the storm
threats could occur area-wide. All the recent convective
development across the western and northern CWA has been tapping
into mostly elevated instability, though concern is increasing
with the evolution of a warm front/lingering wedge front across
portions of north Georgia (currently extending near the Atlanta
Metro to just south of Athens) as this may end up focusing some
stronger rotating convection tapping into more surface based
energy along with localized enhanced low level helicity and
frontogenetic forcing on top of the ample upper forcing/jet
dynamics. The HRRR continues to ramp up the Sig Tor Param along
and south of this feature that could slowly lift northward this
afternoon into evening and bulk shear vectors have strong veering,
so will need to watch for discrete supercell and tornado
potential even ahead of the main overnight expected storms.
Hi-res CAM consensus continues to have expected intense convective
zones/broken lines with embedded supercells pushing into the CWA
after about 04z (midnight) tonight pushing eastward through the
early morning hours. The HRRR indicates impressive swaths of updraft
helicity along these storms interacting with over 400 m2/s2 of 0-1km
SRH, so there is concern of some strong long-track tornadoes, even
more dangerous given the nocturnal timing. Regardless there will be
a widespread damaging wind threat with a robust 65 kt LLJ and 80-100
kts of bulk deep layer shear as the upper wave swings negative.
Have continued with Flash Flood Watch across the far north where
storm total QPF still looks to be in the 2-4 inch range. Also
continuing the Wind Advisory as the enhanced southerly gradient
winds will be strong especially as we get into the warm sector of
the surface low.
The storm threat looks to exit the southeastern CWA between 12-15z
Monday and west to NW winds behind the front should gradually
decrease during the day with clearing conditions.
Baker
LONG TERM /Tuesday through Sunday/...
The forecast remains mainly on track through the extended period,
with only minor changes made based on the latest guidance. The
previous discussion follows...
King
PREV DISCUSSION... /Issued 740 AM EDT Sun Apr 12 2020/
LONG TERM /Monday Night through Saturday/...
Region remains under a fairly active and progressive pattern through
the extended forecast period. Period starts out mainly dry behind the
strong system impacting the area today through early Monday. A short
wave sweeps along the gulf coast region Tuesday bringing rain chances
back into the forecast area, especially the southern portion of the
area. Instability is marginal at best with limited chances for
thunder with this system. Mainly dry for the latter half of the
work-week with rain chances increasing again next weekend as another
wave approaches. Temperatures remain relatively seasonal through the
period.
20
AVIATION...
00Z UPDATE...
Persistent wedge continues its influence over the ATL area
terminals with IFR conditions continuing. Should see these rapidly
transition to MVFR ahead of severe thunderstorm line. Did choose
to add TEMPO to all sites to account for strong wind potential
with line and have 35G45kts for most sites. This may need to be
increased further with subsequent updates. Line timing is still on
track for after 06Z for ATL and after 09Z for AHN and MCN.
Conditions to clear fast behind the line although wind gusts
should continue for several hours after.
//ATL CONFIDENCE...00Z UPDATE...
Medium on IFR duration.
High on remaining elements.
Deese
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 62 76 50 73 / 100 20 5 5
Atlanta 62 73 48 72 / 100 10 5 5
Blairsville 55 66 41 66 / 100 20 5 10
Cartersville 58 69 44 69 / 100 5 5 5
Columbus 65 80 53 80 / 100 10 5 10
Gainesville 59 71 48 69 / 100 10 5 5
Macon 65 81 53 79 / 100 30 5 10
Rome 58 67 44 68 / 100 5 5 5
Peachtree City 62 75 48 74 / 100 10 5 5
Vidalia 68 84 60 83 / 90 80 10 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 AM EDT Monday for the following zones:
Baldwin...Banks...Barrow...Bartow...Bibb...Bleckley...Butts...
Carroll...Catoosa...Chattahoochee...Chattooga...Cherokee...
Clarke...Clayton...Cobb...Coweta...Crawford...Crisp...Dade...
Dawson...DeKalb...Dodge...Dooly...Douglas...Emanuel...Fannin...
Fayette...Floyd...Forsyth...Gilmer...Glascock...Gordon...
Greene...Gwinnett...Hall...Hancock...Haralson...Harris...Heard...
Henry...Houston...Jackson...Jasper...Jefferson...Johnson...
Jones...Lamar...Laurens...Lumpkin...Macon...Madison...Marion...
Meriwether...Monroe...Montgomery...Morgan...Murray...Muscogee...
Newton...North Fulton...Oconee...Oglethorpe...Paulding...Peach...
Pickens...Pike...Polk...Pulaski...Putnam...Rockdale...Schley...
South Fulton...Spalding...Stewart...Sumter...Talbot...
Taliaferro...Taylor...Telfair...Toombs...Towns...Treutlen...
Troup...Twiggs...Union...Upson...Walker...Walton...Warren...
Washington...Webster...Wheeler...White...Whitfield...Wilcox...
Wilkes...Wilkinson.
Tornado Watch until 11 PM EDT this evening for the following
zones: Bartow...Catoosa...Chattooga...Cherokee...Dawson...
Fannin...Floyd...Gilmer...Gordon...Murray...Pickens...Polk...
Walker...Whitfield.
Flash Flood Watch until 8 AM EDT Monday for the following zones:
Catoosa...Chattooga...Dade...Dawson...Fannin...Floyd...Gilmer...
Gordon...Lumpkin...Murray...Pickens...Towns...Union...Walker...
White...Whitfield.
&&
$$
SHORT TERM...Deese
LONG TERM....King
AVIATION...Deese
Area Forecast Discussion
National Weather Service Grand Rapids MI
1053 PM EDT Sun Apr 12 2020
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 328 PM EDT Sun Apr 12 2020
- Stormy Monday
- Cold Tuesday through Friday
&&
.UPDATE...
Issued at 1050 PM EDT Sun Apr 12 2020
We did add some fog to the area for tonight...especially over Lake
MI. The latest HRRR guidance does show a risk for thicker fog for
a period tonight in the nearshore waters. We added the risk to the
HWO as well.
&&
.DISCUSSION...(This evening through next Sunday)
Issued at 328 PM EDT Sun Apr 12 2020
- Stormy Monday
Rain moves in this evening with some elevated instability after
midnight, greatest across the southern half of the forecast area
where we will keep a slight chance of thunder. Then we are dry
slotted Monday morning before some wraparound rain/shower arrives
by afternoon.
The big story continues to be the wind as we expect gusts over 50
mph by late morning into early evening with mixing heights around
4 to 5 kft during that time able to tap 45 knot winds. We have
issued a wind advisory although some gusts to 60 mph are still
possible, most likely across the northeast zones where surface
pressure gradient is strongest as the low deepens over Lake Huron.
The low pulls away Monday night with winds decreasing.
- Cold Tuesday through Friday
The airmass that follows the low is more typical of February than
April with 850 mb temps below minus 10C across central Lower
Michigan on Tuesday and Wednesday. Temperatures should be stuck in
the 30s on Tuesday and Wednesday afternoons and dropping into the
lower to mid 20s at night. Along with the cold comes the chance
for light snow as a minor sfc waves moves across the baroclinic
zone to our south. We will also have to watch for a more
organized low scooting through the ohio valley late in the week.
Some snow or mixed precip could be across our central and southern
zones then.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 723 PM EDT Sun Apr 12 2020
As the storm system nears tonight...the impactful aviation
conditions will be on the increase. Low clouds will eventually
overspread the TAF sites in Southwest Lower MI with IFR or lower
likely later tonight. In addition the showers will temporarily
lower VSBYS...especially after midnight. Then for Monday the wind
shifts early and increases considerably. Gusts over 35 knots are
forecasted for all sites. VSBYs and ceilings will be on the
increase during the day as drier air works its way in from the
west.
&&
.MARINE...
Issued at 328 PM EDT Sun Apr 12 2020
No changes to the Gale Warning and Coastal Flood Warning. Still
expecting northwest gales over 40 knots from Monday morning into
the evening with 10 to 14 foot waves. The highest waves and worst
erosion and coastal flooding is expected from Grand Haven to South
Haven. Conditions will begin to improve Monday night.
&&
.HYDROLOGY...
Issued at 328 PM EDT Sun Apr 12 2020
QPF has decreased with this forecast update to a half inch or less
although some higher amounts are well within the realm of
possibility. We expected some modest rises on the rivers this week
but not expecting flooding. SOme sites to watch are those that
are near bankfull already like Ionia, Holt, Maple Rapids and
Vicksburg.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Lakeshore Flood Warning from 5 AM Monday to 5 AM EDT Tuesday for
MIZ037-043-050-056-064-071.
Wind Advisory from 8 AM to 8 PM EDT Monday for MIZ037>040-
043>046-050>052-056>059-064>067-071>074.
LM...Gale Warning from 5 AM Monday to 5 AM EDT Tuesday for LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...MJS
HYDROLOGY...Ostuno
MARINE...Ostuno
Area Forecast Discussion
National Weather Service Lincoln IL
901 PM CDT Sun Apr 12 2020
.SYNOPSIS...
Issued at 254 PM CDT Sun Apr 12 2020
Showers and scattered thunderstorms will accompany a cold front,
which will sweep across Illinois tonight. As the front passes,
winds will significantly increase, and will gust from 40 to 50 mph
late tonight into Monday. This will mark the start of much cooler
conditions, which will persist most of the week, and resulting in
below freezing temperatures each night beginning Monday night.
&&
.UPDATE...
Issued at 900 PM CDT Sun Apr 12 2020
A cold front has reached roughly the Illinois River this evening,
with a fine line of isolated heavy showers and a trailing region
of widespread rain trailing behind. Instability has almost totally
diminished, so have trimmed out thunder mention except for a
slight chance around Jacksonville area mid evening and around I-70
southward from midnight to 4 am. Otherwise, forecast is on track
with temperatures dropping dramatically into the 30s behind the
front and strong northwest winds 20-30 mph with gusts 40-50 mph
developing overnight.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 254 PM CDT Sun Apr 12 2020
Earlier clear slot from Missouri into northern Illinois is still
visible on satellite imagery, but high clouds have spread over top
of it. This has allowed temperatures to reach the mid 60s toward
Galesburg, though upper 50s/lower 60s prevail elsewhere early this
afternoon. After a few hours of dry conditions, showers are
starting to increase again, which has been hinted at by recent
HRRR runs. Showers/storms are also starting to lift northeast of
the Ohio River, as a shortwave ejects out of Missouri.
Main synoptic front analyzed just west of Cedar Rapids IA into
east central Kansas, and is expected to begin entering the western
CWA just after sunset. Highest PoP`s are aligned with its passage,
with the front near the Indiana border by about 3 am. Associated
rainfall should largely be out of the area by sunrise. Behind the
front, winds quickly ramp up and be gusting from 40-50 mph by
early morning. In collaboration with neighboring offices, have
extended the Wind Advisory until 7 pm Monday, though conditions
south of I-72 will be diminishing a bit by mid afternoon.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 254 PM CDT Sun Apr 12 2020
Longer range focus will be on the much cooler conditions, with
nightly temperatures at or below freezing. Vegetation across the
south half of the forecast area has advanced far enough that
frost/freeze headlines will likely be needed at various points.
Improvement is expected by next weekend, as highs return to the
60s.
With the broad northwest flow, weak disturbances through mid week
will be capable of squeezing out some precipitation at times, with
the best chance late Tuesday and early Wednesday. Further out, as
the flow starts to become more zonal and split, an elongated
west-east boundary will provide the focus for additional
precipitation. The GFS is standing alone with a deep wave in the
northern flow, resulting in a deep surface system and raw snowfall
projections of several inches across the northern CWA Thursday
night and Friday. Having a hard time buying into this, and will
mainly stick with a rain mention, with rain/snow across the north.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 640 PM CDT Sun Apr 12 2020
MVFR conditions are predominant across central IL early this
evening, with a few breaks in the cloud cover just ahead of a cold
front approaching the Mississippi River. This front and associated
showers and thunderstorms will sweep across central IL late this
evening, bringing an abrupt wind shift to strong NW winds, a
return to IFR and MVFR cigs, and some MVFR vsbys as well. SHRA
will gradually taper off after 06-08Z, while MVFR cigs are
expected to return by 09Z-10Z, then gradually lift to VFR by
15Z-18Z. Winds S around 10 kts until 05-08Z becoming NW 20-25 kts
with gusts 35-40 kts from around 09-15Z. Winds should diminish
several kts from 18Z-24Z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from midnight tonight to 7 PM CDT Monday for
ILZ027>031-036>038-040>057-061>063-066>068-071>073.
&&
$$
UPDATE...37
SYNOPSIS...Geelhart
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...37
Area Forecast Discussion
National Weather Service Louisville KY
948 PM EDT Sun Apr 12 2020
.Forecast Update...
Issued at 948 PM EDt Sun Apr 12 2020
Currently in a precipitation lull except for just a few showers in
south-central KY. Deep convection is ongoing in the warm sector
across the Deep South and along the cold front in Arkansas. An
elongated area of sfc low pressure is oriented roughly along the
Mississippi River Valley. Sfc low pressure is still forecast to
deepen to the northeast overnight just downstream of a vigorous,
compact shortwave trough. The severe threat overnight is still very
conditional on any available instability, and would also say that
threat appears more marginal now.
Any developing sfc based instability will be tied to the sfc low`s
ability to draw warm, moist air further north. Sfc dewpoints are
currently running in the mid to upper 50s, with upper 50s confined
to the Lake Cumberland region. Based on the latest hi-res data,
think we will see dewpoints rise into the upper 50s/lower 60s. This
is a strong system with impressive low level wind fields, so a
modest dewpoint rise does make sense.
Will have to watch a couple areas of convection, the first being
heavier showers moving northeast from Middle TN. That activity will
spread into southern KY around 930-1000 PM CDT. Think we could see
some strong wind gusts, but instability will still be quite meager
in the 03-04z time frame. The second area to watch is the line of
storms along the front in Arkansas. It does appear that convection
will be able to sustain itself for at least another 2-3 hours, but
the HRRR generally suggests a somewhat weaker band of showers (still
of convective nature) in the 07-13z time frame. This window,
generally along and behind the actual front, may bring a more
widespread potential for strong wind gusts.
Fcst soundings show moist adiabatic low level lapse rates along the
front, with a little elevated instability. So these showers, coupled
with the better mixing and strong PGF immediately behind the front,
will likely result in at least 40-50 mph winds.
Issued at 619 PM EDT Sun Apr 12 2020
Widespread moderate rain has overspread the region in an area of
strong warm air advection and on the nose of the max 925-850 mb
moisture transport currently over TN and AL. Fortunately, current
sfc based instability is nil. We are watching one narrow convective
line push northeast across Middle TN, but this feature is likely to
remain sub-severe when it moves NE across the Lake Cumberland
region. Low to mid level wind fields and shear profiles are quite
impressive, but the lack of instability will make it quite difficult
to realize severe wind gusts. KBNA had a gust to 30 kts from 280
when the line crossed.
Widespread clouds and precip have helped keep instability to a
minimum. Sfc dewpoints are running in the low to mid 50s as of this
writing. While dewpoints could surge a few degrees in the Lake
Cumberland region over the next 1-2 hours as that narrow convective
line approaches, it likely won`t be enough to significantly increase
the severe threat. So overall, the severe threat with this first
wave appears to be marginal. There may be some minor flooding issues
in that region as well, including the counties of Monroe,
Cumberland, Clinton, and Russell. Dual-pol radar estimates around
1.5 inches of rain has fallen thus far across a good chunk of those
counties. The relatively brief heavier convective rates upstream may
very well produce ponding of water and general minor flooding in low
lying areas and any areas typically susceptible to flooding. But
with a sizable lull not far off behind this first wave, think the
flash flood threat is low/very isolated at this time.
&&
.Short Term...(This evening through Monday)
Issued at 305 PM EDT Sun Apr 12 2020
...Strong to Severe Storms Possible Tonight...
Main focus remains on tonight as strong to severe storms will be
possible over the area as a compact shortwave trough ejects out of
the lower MS Valley and pushes across the OH Valley overnight.
Besides some scattered shower activity earlier today, this afternoon
has been mostly dry and overcast, although a more widespread area of
light to moderate showers is now beginning to push northward into
southern KY, with some rumbles of thunder and lightning possible.
Farther south, an ongoing MCS with a history of producing tornadoes,
damaging winds, and hail is moving northeast across LA/AR/MS. As we
look to our own severe potential tonight, a lot of uncertainty
remains as our ability to destabilize will hinge on how much these
southern storms rob us of sufficient instability and moisture. The
SPC`s southward pull of the Enhanced Risk to about the KY/TN border
reflects the lowered confidence in our ability to destabilize later
tonight.
Expect showers and storms to overspread the area this evening and
into tonight as we see increasing lift under a 50-60 kt LLJ ahead of
the ejecting shortwave. Model soundings indicate any instability
would likely remain elevated at this point, although wind profiles
will be quite impressive with 0-6 km Bulk Shear values of 50-60 kts
and 0-3 km ESRH of 200-400 m2/s2. Expect areas of heavy rainfall as
PWATs increase to around 1.5 inches, and some embedded rumbles of
thunder will also be possible. Another wave of showers and storms
will be possible overnight as an initial area of convection is
expected to develop near the surface low over southeast OK later
this afternoon and move northeastward, reaching our region after
Midnight EDT. With favorable wind profiles still in place, the
question mark will remain whether or not we are able to destabilize
at all. If any storms this evening and overnight are able to become
surface based, damaging winds will be the main threat, although an
isolated tornado cannot be ruled out. The most likely area for
seeing any surface based instability will be across southern KY,
where stronger moisture and instability advection may occur.
Behind storms, expect strong wind gusts across the region starting
late Sunday night and into Monday morning as the pressure gradient
tightens around the departing low. Wind gusts of 40-50 mph will be
possible, with peak winds being observed early Monday morning
between 10-12Z. The strongest winds are expected to occur over south-
central KY, where wind gusts will approach High Wind Warning
Criteria. However, confidence is not high enough at this time to
upgrade the Wind Advisory.
Precipitation chances will end from west to east Monday morning
behind the cold front, leaving us cool and dry for the rest of the
day. Winds will gradually decrease through the afternoon as the
pressure gradient relaxes and a surface high begins to nudge its way
into the region. Temperatures will fall into the mid 40s to low 50s
by late morning and generally remain in this range through the
afternoon.
.Long Term...(Monday night through Sunday)
Issued at 305 PM EDT Sun Apr 12 2020
Winds will die down Monday evening, but even with temps dropping
into the mid 30s there will be enough cloud cover to limit any frost
concerns Tuesday morning. Much of the upcoming work week will be
unseasonably cool as broad upper trofiness covers most of the
eastern CONUS. Could be a few disturbances in the quasi-zonal flow,
but POPs will be limited due to uncertainty in the timing. Any
mornings with precip chances will pose a precip type issue, while
the drier mornings could involve frost if skies are clear. Plenty of
bust potential with clouds so will not make any specific frost
mentions yet.
A sharper shortwave trof will bring better precip chances on Friday,
and could also involve thunder. That system will be followed by a
Pacific air mass, so temps will recover to near climo for next
weekend.
&&
.Aviation...(00Z TAF Issuance)
Issued at 757 PM EDT Sun Apr 12 2020
Widespread rain has cleared out of BWG/HNB/SDF and will quickly
clear LEX over the next half hour. There may still be a few showers
around through the evening, but the bulk of precipitation will hold
off until a second round late tonight/early Monday. In the meantime,
the main challenge will be low ceilings mostly in the low MVFR or
IFR range at BWG/SDF/HNB. LEX may actually go back to VFR for a
while this evening. Winds will be steady out of the SE.
A strong surface low will move through the area through the
overnight with strengthening S and the W surface winds as it passes.
The W winds will likely gusts up above 45 mph at times, with more
common sustained gusts above 35 mph. There may be a few
showers/storms associated with this feature between Midnight and
dawn, but overall confidence is fairly low. Best chance for low MVFR
and even IFR ceilings will be at BWG/SDF/HNB through the overnight.
Once winds go to a W direction, expect rapid improvement in ceilings
back to VFR by late morning or early afternoon. Winds will gradually
decline through the afternoon, but will remain gusty through the end
of the cycle.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Wind Advisory from 2 AM EDT /1 AM CDT/ to 2 PM EDT /1 PM CDT/
Monday for INZ076>079-083-084-089>092.
KY...Wind Advisory from 2 AM EDT /1 AM CDT/ to 2 PM EDT /1 PM CDT/
Monday for KYZ023>043-045>049-053>057-061>067-070>078-081-
082.
&&
$$
Update...EBW
Short Term...JML
Long Term...RAS
Aviation...BJS
Area Forecast Discussion
National Weather Service Memphis TN
833 PM CDT Sun Apr 12 2020
.DISCUSSION...
Skies are cloudy across much of the Mid-South this evening with
temperatures from the mid 50s to around 70 degrees. The first
area of thunderstorms is finally moving out of the eastern side of
the Mid-South with another large area of thunderstorms about to
enter the region from the west. Some of these thunderstorms could
produce damaging winds and large hail so a Severe Thunderstorm
Watch has been issued for roughly the western half of the Mid-
South until 1 AM CDT.
ARS
&&
.PREV DISCUSSION... /issued 412 PM CDT Sun Apr 12 2020/
UPDATE...Updated to remove the Tornado watch from North
Mississippi. Redevelopment looks questionable at this time.
Adjusted pops/weather accordingly.
30
PREV DISCUSSION... /issued 223 PM CDT Sun Apr 12 2020/
DISCUSSION...
SEVERE WEATHER IS STILL POSSIBLE THIS AFTERNOON AND EVENING...
A tornado watch remains in effect for North Mississippi. The last
few HRRR runs backed off of the 2nd round of thunderstorms this
evening, but has now increased coverage once again. However, the
surface low that was once well defined, tracking just South of
Memphis is much more diffuse as it tracks into West TN. The warm
front remains to our South but should begin to surge North over
the next few hours ushering in mid-60 degree dew points into
portions of North Mississippi. As this deeper moisture arrives, a
shortwave trough and 70kt mid level jet will shift across the
area. Low level shear remains impressive, 0-1km SRH in excess of
400 m2/s2 should be more than sufficient to support supercellular
storms capable of producing tornadoes and widespread damaging
wind. The main limiting factor will be surface based instability,
which will remain limited until the warm front surges North. The
highest potential for a strong long tracked tornado will likely be
right along or just North of the warm front before sunset.
It is highly uncertain if additional storms will develop along the
cold front but if they do, conditions will be favorable for fast
moving short lived tornadoes as well as damaging wind. By
Midnight, the threat of any severe weather should be over.
Cooler conditions will arrive tomorrow. Expect temperatures
around 15 degrees below normal Monday and Tuesday with highs in
the 50s followed by a warming trend Wednesday and Thursday. By
Thursday we should see highs in the middle to upper 60s across
most of the Midsouth. There could be frost across portions of West
Tennessee, the Missouri Bootheel and Northeast Arkansas Tuesday
and Wednesday mornings.
A broad trough will deepen over much of the Eastern US Early in
the work week, a weak disturbance rounding the base of the trough
could result in a few light showers Tuesday, but otherwise dry
conditions are expected through Friday.
Expect near to slightly below normal temperatures Friday into the
weekend. No organized storm systems are expected though it looks
like a few additional showers are possible Friday night.
30
&&
.AVIATION...
00Z TAF cycle
Low clouds will continue to cover much of the Mid-South tonight
and will remain through the overnight hours. Showers and
thunderstorms are moving across portions of north Mississippi at
this time. Additional showers and thunderstorms will move into the
region late tonight. Winds will be mainly from the south at 10 to
15 knots this evening before gradually shifting to the west and
increasing to 15 to 20 knots and gusty overnight.
ARS
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Flash Flood Watch until 1 AM CDT Monday for Clay-Craighead-
Crittenden-Cross-Greene-Lee AR-Mississippi-Phillips-
Poinsett-St. Francis.
Wind Advisory until 7 AM CDT Monday for Clay-Craighead-
Crittenden-Cross-Greene-Lee AR-Mississippi-Phillips-
Poinsett-St. Francis.
MO...Flash Flood Watch until 1 AM CDT Monday for Dunklin-Pemiscot.
Wind Advisory until 7 AM CDT Monday for Dunklin-Pemiscot.
MS...Flash Flood Watch until 1 AM CDT Monday for Alcorn-Benton MS-
Calhoun-Chickasaw-Coahoma-DeSoto-Itawamba-Lafayette-Lee MS-
Marshall-Monroe-Panola-Pontotoc-Prentiss-Quitman-
Tallahatchie-Tate-Tippah-Tishomingo-Tunica-Union-Yalobusha.
Wind Advisory until 7 AM CDT Monday for Alcorn-Benton MS-Calhoun-
Chickasaw-Coahoma-DeSoto-Itawamba-Lafayette-Lee MS-Marshall-
Monroe-Panola-Pontotoc-Prentiss-Quitman-Tallahatchie-Tate-
Tippah-Tishomingo-Tunica-Union-Yalobusha.
TN...Flash Flood Watch until 1 AM CDT Monday for Benton TN-Carroll-
Chester-Crockett-Decatur-Dyer-Fayette-Gibson-Hardeman-
Hardin-Haywood-Henderson-Henry-Lake-Lauderdale-Madison-
McNairy-Obion-Shelby-Tipton-Weakley.
Wind Advisory until 7 AM CDT Monday for Benton TN-Carroll-
Chester-Crockett-Decatur-Dyer-Fayette-Gibson-Hardeman-
Hardin-Haywood-Henderson-Henry-Lake-Lauderdale-Madison-
McNairy-Obion-Shelby-Tipton-Weakley.
&&
$$
Area Forecast Discussion
National Weather Service Miami FL
733 PM EDT Sun Apr 12 2020
.Aviation...
There could be periods of MVFR conditions tonight as some lower
cloud cover tries to develop across the region. Southeasterly wind
flow will continue overnight at 10 to 15 knots. These winds will
shift to a more southerly direction on Monday and increase in
speed to 15 to 20 knots with higher gusts. Dry conditions should
prevail across all terminals on Monday.
&&
.Update...
Mainly dry conditions will occur across the region tonight as a
breezy southeasterly flow continues across South Florida. The
winds will begin to shift to more of a southerly direction on
Monday, however, the speeds will increase and range between 15 and
20 mph with some higher gusts especially later in the morning and
into the afternoon hours. Mainly dry weather will remain in place
across South Florida due to the area of high pressure located in
the western Atlantic. Warm temperatures will prevail on Monday as
highs will range from the upper 80s across the east coast to the
mid 90s across the interior sections.
&&
.Prev Discussion... /issued 232 PM EDT Sun Apr 12 2020/
Short Term...
Today and tonight...
Looking at the potential for convection, models are mixed. Some
models show little in the way of any convection over South
Florida. Then other models, including the GFS and the HRRR show
the potential for convection across portions of the area,
especially in the Lake region. Currently, there is only a slight
chance in the forecast. The question is if convection will be able
to initialize or not. The GFS was more optimistic with around 1.75
inches over much of the area for the day. the NAM was somewhat
drier this morning, then showed some moisture advecting into the
area this afternoon. Looking at the visible sat imagery, there
appears to be a slot of drier air along the Gulf coast, with
higher amounts of moisture over the remainder of the CWA, as
shown by the amount of cloud cover. The frontal boundary, that was
to the south currently appears to be connected with the
demarcation of the cloud/moisture field, and is lifting north as
a warm front. Temperatures behind the front are a few degrees
higher than to the east of the front. With the front providing
some weak lift in the western Lake region, along with models
indicating lapse rates from the sfc to about 3km at 8.3 C/km,
convective initiation is possible. However, at 500mb, there is a
ridge building, with minor height rises at that level. There is
some shear, with the effective shear at 45kts on the NAM model
sounding. The helicity is weak, at lower than 100 and the freezing
level should be around 14500 ft. The model sounding is also
showing some features, such as an inverted V and a dry layer at
around 700mb. At about 350mb, there is a jet, with wind around
65kts. Putting this all together, it indicates that if convection
is able to initiate, there is a potential for hail, at least small
hail, if not moderate size, but still under 1 inch. The inhibiting
factor in large hail possibility would be how strong the jet is.
At 65 kts, it may cause too much lean to any storms for the
updraft to keep any hail stones within it long enough to grow to
larger than 1 inch. but again, that is dependent on the exact
speed and location of the updraft in each storm. So there would
still be a non zero chance of large hail. Lending to aid in this
would be the NCAPE of over.2, indicating some decent vertical
velocity possible with the storms. Now, along with that, the
stronger vertical velocity may allow some of the cores of any
storms that are able to develop to tap into the higher speeds
aloft. The 500mb temp is forecast to be around -8.4C, indicating
at least a cool, if not a cold pool aloft. If the storm is able to
develop with the core into the cold pool and higher wind speeds,
any downbursts could contain wind speeds of at least 60kts,
especially with the inverted V sounding. Again, this is all
conditional, and based on convection being able to initiate. The
chances are very small, but they are non zero for this afternoon
and evening.
One other parameter that could come into play is the Lake shadow
effect. This may cause some differential heating, which could aid
in the development, and also may allow for a boundary strong
enough to allow an isolated waterspout to be possible. Again,
there is a large amount of uncertainty with any of the above
scenarios occurring, so it is very possible that it does not
materialize. But, if convection is able to occur in the Glades and
Hendry County area, there is a potential for some strong to severe
storms to materialize.
Once we lose daytime heating and the front has moved into central
Florida, the remainder of the night should be dry, with a
continued southeast wind.
Tomorrow and tomorrow night...
The high pressure sitting to the east is progged to maintain the
south southeast wind. The models are showing that the weather
should remain dry through Monday night, with a warming trend in
place. Highs Monday are forecast to be in the upper 80s along both
coasts, and in the mid 90s for the interior areas. Lows are
forecast to be in the upper 60s to mid 70s along the coasts.
Long Term (Tuesday through Saturday)...
The cold front enters the peninsula of Florida on Tuesday morning
as the parent low pressure system moves northward into Canada. The
front will end up stalling somewhere in north central Florida
before the next impulse arrives on Wednesday. This impulse will
not be enough to push the boundary south of Central Florida. With
the boundary located to the north of the area, temperatures will
continue to remain warm with rain chances remaining non-zero each
day.
As the next mid-level moves across the central United States, a
surface low will develop over the plains and enter the Ohio River
Valley and Great Lakes regions on Friday. This system will provide
reinforcement to the stall boundary that will propel it southward
again. With this boundary moving closer, shower and thunderstorm
chances will increase to close out the week and kick off the
weekend.
Uncertainty remains in the location and timing of the frontal
boundaries in the long term period of the forecast. A more
progressive or southward stall could bring increased unsettled
weather to the region along with cloud cover which could allow for
slightly cooler temperatures than forecast. On the flip side, less
southward progress than forecast could keep the region on the warm
side of guidance with the potential for record heat and parched
ground conditions. Will need to monitor the evolution of these
features over the week to see how they will influence any
mesoscale factors that come into play like remnant boundaries from
previous convection, sea breeze development and progression, and
the potential for enhanced convection.
Marine...
Breezy conditions are forecast to continue, which may bring
hazardous marine conditions to the South Florida waters at least
through Monday morning. Conditions are forecast to begin to
improve Monday under high pressure. However, there is a potential
the wind may not subside quick enough and the Small Craft
Advisory, currently in effect through Monday morning, may need to
be extended. Otherwise, quiet weather is forecast through the
middle of the week, with chances of rain increasing for the end of
the week, mainly for the Atlantic waters.
Aviation...
Abundant cloud cover across South Florida may bring some brief IFR
conditions as cigs briefly drop. However, breezy conditions will
cause the cloud cover to vary fairly rapidly though the night.
There is a potential for SHRA or TSRA in the Lake region through
the evening hours. Tomorrow should see dry weather, with the wind
becoming more southerly and remaining breezy.
Beach Forecast...
Breezy conditions out of the southeast, are bringing enhanced risk
of rip currents for the Atlantic coast. There is a high risk of
rip currents today, and possibly tomorrow, although tomorrow
should see conditions begin to improve. Even so, the risk of rip
currents may continue to be enhanced through the middle of the
week.
&&
.Preliminary Point Temps/PoPs...
West Palm Beach 76 90 74 88 / 0 0 10 20
Fort Lauderdale 78 88 77 87 / 10 0 10 10
Miami 78 88 76 88 / 0 0 10 10
Naples 76 88 74 89 / 0 0 0 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Monday morning for FLZ168-172-173.
AM...Small Craft Advisory until 8 AM EDT Monday for AMZ610.
Small Craft Advisory until 8 AM EDT Monday for AMZ630-650-651-
670-671.
GM...Small Craft Advisory until 8 AM EDT Monday for GMZ656-657-676.
&&
Update...55/CWC
Aviation...55/CWC
Area Forecast Discussion
National Weather Service Marquette MI
1109 PM EDT Sun Apr 12 2020
.UPDATE...
Issued at 1108 PM EDT SUN APR 12 2020
No major changes have been made to the fcst this evening. A little
concerned that the western fcst area could underperform on snow
totals as radar trends indicate heavier pcpn will end up a bit
farther e than anticipated, which evening HRRR runs and incoming 00z
models indicate. Strengthening winds/upslope later tonight/Mon
morning is a plus to enhance accumulations, but opted to cut back
snow accumulations a couple of inches over the w given the eastward
shift of heavier synoptic pcpn. Given the eastward shift, total snow
accumulations were nudged up 1-2 inches in a corridor from western
Alger county to northern Menominee County.
Interesting item of note for later Monday will be the sfc
trof/enhanced convergence zone extending from well nw of Thunder
Bay, Ontario se across the Keweenaw to Alger County. Recent days
model runs have consistently indicated this sfc trof, though in
varying locations. Last 12hrs of model runs are converging on the
trof extending across Keweenaw County to Alger County. Will be a
feature to watch late Mon aftn/evening for intense snowfall.
&&
.SHORT TERM...(This evening through Monday)
Issued at 450 PM EDT SUN APR 12 2020
WV imagery and RAP analysis indicated a mid/upper level trough from
northern Manitoba through the western Plains resulting in sw flow
through the western Great Lakes. A vigorous southern stream
shortwave was lifting northeast from OK/TX. A 140 knot 300 mb jet
streak was draped through northwest Ontario. At the surface, an
inverted trough extended to northern Lower Michigan from a 998 mb
low over eastern OK. Upper level div from the right entrance of the
Ontario jet and the associated broad area of deep isentropic lift,
supported heavy pcpn from IA and se MN into Upper Michigan. Moderate
to heavy snow was observed northwest of an IMT-RST line with rain to
the south.
Tonight, Continue strong isentropic lift with strong 50 knot
flow/moisture transport bringing 295k-300k level(around 700 mb)
mixing ratio values of 5g-6g/Kg toward Upper Michigan. Expect a
period of very heavy snow tonight with impressive QPF to near 1.5
inch north central where lake and orographic enhancement is
strongest. Values closer to 0.8 inch are expected through most of
the rest of upper Michigan. The relatively wet snow with snow/water
ratios near 10/1 will result in widespread snow totals of from at
least 8 to 16 inches.
Forecast soundings along with Models consensus Bourgouin energy
values support mainly rain over the east with a pivoting band of
mixed fzra/ra and sleet into the south and east central and snow
over the west half. Temps near or only slightly below freezing
should limit ice accumulation to around a tenth of an inch despite
the heavy pcpn amounts.
Monday, the deepening low pressure center over eastern Upper
Michigan will continue to deepen and lift to the northeast. Any
lingering mixed pcpn over the east will quickly shift east as the
colder air moves in early. The very tight pressure gradient will
support winds gusting to 40-50 mph, per forecast soundings
momentum transfer prog. Although the support for the heavier pcpn
will diminish during the morning as the stronger 700-500 mb fgen
shifts to the east, lake enhance snow whipped by the strong winds
will result in very low vsby with local whiteout conditions
possible. Additional snow totals should remain in the 3 to 6 inch
range, highest over the Keweenaw and north central. Amounts of
around an inch or less are expected over the south. Wave heights
of up to 15-20 ft will also result in some lakeshore flooding and
beach erosion for locations exposed to the north winds.
.LONG TERM...(Monday night through Sunday)
Issued at 335 PM EDT SUN APR 12 2020
The main focus in the extended is the lingering lake-effect snow
band that models continue to resolve across parts of the northwest
wind snow belts Tuesday night through early Wednesday morning.
Otherwise, the extended with feature well-below normal temperatures
through at least the end of the week as numerous shortwaves rotate
down across the region and advect in weak, reinforcing shots of cold
air. These shortwaves arriving on a nearly daily basis will also
allow for some diurnally driven shower activity through the end of
the week.
Tuesday night into Wednesday morning a shortwave is progged to dig
south across the region bringing in colder air aloft and additional
lift to support the maintenance of the above mentioned stronger
lake-effect snow band. In fact, soundings show inversion heights
increasing overnight to around 10kft, more that sufficient for the
production of a deep-convective snow band. 850mb temperatures
hovering around -13C will also favor lift through the DGZ, but given
the depth of the lift and 20-30 kt winds spanning the convective
layer, think the SLRs will be a bit lower compared to our typically
super fluffy lake-effect snow. So do have a higher QPF, lower SLR
combo which results in an additional 3-5 inches of snow across the
Keweenaw Peninsula, stretching southeast towards the Michigamme
Highlands/Big Bay, and back over towards Alger/Schoolcraft counties.
As for the city of Marquette, right now it looks like this heavier
band of lake-effect snow will sit just offshore, given the more
westerly gradient winds at the surface.
On Wednesday, this stronger lake-effect snow band pushes offshore,
but we could see a diurnal flareup of snow showers across the
interior with daytime heating. Thursday will feature another
shortwave traversing the region and possible diurnal flareup of
shower activity. Temperatures will be a bit warmer, so there could
be some very light rain that mix in with the snow showers in spots.
Overnight lows through mid-week will be on the chilly side across
the interior, where single digits will be possible.
For the end of the week into next weekend, we look to remain
sandwiched between high pressure to the south and a low tracking
north of the border in Canada. Thus we will gradually find ourselves
under a bout of return flow, which will usher in a gradual warm up
back towards normal. Towards the middle/end of next weekend, the
surface low north of the border looks to push a cold front down
across the region, bringing back chances for precipitation. Ahead of
this front, we should see warm and breezy conditions return briefly,
followed by another cool down.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 801 PM EDT SUN APR 12 2020
Snow, mdt to hvy at times, will continue thru the night at
KIWD/KCMX/KSAW. As a result, LIFR conditions will generally prevail
at all terminals. With snowfall heaviest at KSAW, conditions may be
blo airfield landing mins for much of the night. Conditions at KCMX
may also fall blo land mins at times overnight. Winds will increase
during the night and remain strong thru Mon as deepening low pres
lifts across the Great Lakes region tonight and into Quebec by Mon
evening. All terminals will see gusts to 30-40kt on Tue. Although
snow will diminish Mon (ending at KIWD), there is some uncertainty
in how long blsn will maintain poor vis. Given the strength of the
winds, conditions may remain LIFR and at times blo airfield landing
mins at least thru the morning, especially at KCMX/KSAW. KIWD should
improve to VFR by mid aftn. By late aftn, improvement to IFR should
occur at KCMX and to MVFR at KSAW.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 450 PM EDT SUN APR 12 2020
Winds will continue as winds increase quickly late tonight in
response to the deepening low pressure center moving toward eastern
Upper Michigan. As the low moves off to the northeast Monday and
continues to deepen, expect the strongest winds as colder air is
pulled in. Gale warnings west and Storm warnings east remain in
effect through Mon evening. By Mon evening, deep low pres will be
located s of James Bay. A ridge of high pressure will slowly build
in behind this exiting low pressure system on Tuesday as winds
gradually diminish below 20 knots by Tuesday evening.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Storm Warning until 2 AM EDT /1 AM CDT/ Tuesday for
MIZ001>003-009-084.
Winter Weather Advisory until 8 AM EDT Tuesday for MIZ085.
Lakeshore Flood Warning from 8 AM to 8 PM EDT Monday for MIZ001-
003.
Lakeshore Flood Warning from 8 AM Monday to 2 AM EDT Tuesday for
MIZ005>007.
Winter Storm Warning until 8 AM EDT Tuesday for MIZ004>006.
Winter Weather Advisory from 6 AM to 8 PM EDT Monday for MIZ007-
014.
Winter Storm Warning until 5 PM EDT /4 PM CDT/ Monday for MIZ010-
011-013.
Winter Weather Advisory until 4 PM CDT Monday for MIZ012.
Lake Superior...
Storm Warning from 8 AM Monday to 2 AM EDT Tuesday for LSZ251-
267.
Storm Warning until 2 AM EDT Tuesday for LSZ249-250-266.
Gale Warning from 5 AM EDT /4 AM CDT/ to 10 PM EDT /9 PM CDT/
Monday for LSZ240>248-263>265.
Gale Warning from 5 AM EDT /4 AM CDT/ to 8 PM EDT /7 PM CDT/
Monday for LSZ162.
Lake Michigan...
Gale Warning from 8 AM to 11 PM EDT Monday for LMZ221-248-250.
&&
$$
UPDATE...Rolfson
SHORT TERM...JLB
LONG TERM...Ritzman
AVIATION...Rolfson
MARINE...JLB
Area Forecast Discussion...CORRECTED
National Weather Service Pocatello ID
218 PM MDT Sun Apr 12 2020
.SHORT TERM (Today - Wednesday AM)...
Much quieter across eastern Idaho this afternoon compared to 24
hours ago although it`s also quite a bit colder too. Strong cold
front has brought much colder temperatures to the region that will
stick around for a few days before a gradual warmup begins for
the upcoming week. As far as sensible weather is concerned for the
next few days, seeing mostly to partly sunny skies across much of
the area this afternoon. Some of the hi-res model guidance namely
the NAM and HRRR show the potential for some clouds and light
snow showers to move southeast out of the central mountains and
into portions of the Snake Plain later this afternoon and into the
evening. That being said, added a chance of snow showers from
Pocatello west through American Falls and over towards Minidoka.
If any snow showers did occur in these areas they would likely be
very light without too much impact. Overnight temps will be cold,
near records in spots with upper teens and lower 20s looking
likely. Record low for tomorrow at Pocatello is 17 and the
forecast currently sits at 18. Monday will be very similar to
today temperature wise although looks like cloud cover will be a
touch less in spots. Temps begin to moderate Tuesday back closer
to normal for mid-April as the next system looks to approach the
region around daybreak Wednesday. McKaughan
.LONG TERM (Wednesday - Sunday)...
No major changes noted in the long-term portion of the forecast. Our
next storm system (a shortwave trough dropping in from the north)
remains progged to spread rain and snow showers across the area Wed
and Wed night. A few thunderstorms and breezy conditions are also
possible Wed afternoon. QPF amounts still don`t look overly
impressive with this system, with perhaps a few inches of snow for
the mntns. Models linger a few showers into Thurs, but this should
be post-trough and post-front, so suspect much of the region will be
dry. This is the main feature in the long-term as far as impacts go,
and at this time impacts appear fairly limited. Forecast confidence
is moderate through Thurs. The GFS/EC/Canadian have trended weaker
and further west with the potential coastal low toward the end of
the week/next weekend, so odds favor predominantly dry conditions
for our forecast area, but model agreement in the details remains
low from Fri onward. We made very few deviations from NBM guidance.
Temps will gradually warm through the period, from below normal to
just above normal by the weekend. - KSmith
&&
.AVIATION...
VFR cigs/vsbys are expected across southeast Idaho for the next 24
to 36 hours, with no major aviation impacts. NE winds will remain
breezy this afternoon at the Snake Plain terminals but gradually
subside into the eve. LLWS is not expected, as winds only gradually
increase with height. A shower can`t be ruled out near KSUN or KBYI.
NAM time-heights remain insistent that a BKN to OVC mid-level deck
will develop for awhile this eve at KPIH/KIDA/KDIJ. It`s possible,
but other guidance like the HRRR cig products are not so
pessimistic, and we see no obvious source of this inbound on
satellite imagery, so we backed this off to SCT in the 18z TAF
package and will monitor. Dry conditions expected tonight. - KSmith
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
311 PM MDT Sun Apr 12 2020
.SHORT TERM...(This evening through Monday)
Issued at 250 PM MDT Sun Apr 12 2020
Currently...
Mostly cloudy to cloudy skies prevail across the plains, while the
mtns and valleys had partly cloudy skies. Temperatures have remained
quite cold over the lower elevations as temps were only in the 20s
and 30s across the plains, while the San Luis Valley has warmed into
the mid 50s. Some light radar echoes were still noted generally north
of US50 over the plains, but this precip is likely very light.
Rest of today and tonight...
Main concern is the cold temperatures expected tonight. Guidance
continues to forecast lows reaching down into the teens to around 20
over the valleys and plains and negative and positive single digits
in the mountains. Any sensitive plants that have germinated may have
a hard time with these temps tonight, and any exposed pressurized
outside water pipes will likely freeze.
Cant rule out some continued light snow continuing along the
mtns/plains interface as continued upslope flow is expected through
tonight. This is especially true over northern Teller county this
evening if the HRRR is correct. This upslope flow will also likely
keep cloudiness over the plains with areas of low cigs, especially
across El Paso county.
Tomorrow...
Continued cyclonic flow aloft will continue weak upward vertical
motion over the entire region throughout the day. This combined with
continued upslope flow will allow for snow showers to continue over
the high terrain, and especially on the east slopes of the
mtns/plains interface. Likewise, kept highest pops over this region
throughout the day tomorrow. Temps should be a few degrees warmer
than today, with max readings in the 30s to lower 40s, The SLV
should once again be the warmest location with readings in the mid
to upper 40s expected. The overall best chance of accumulating snow
tomorrow should be Teller and northern El Paso counties where 1 to
possibly 3 inches could occur, especially later in the day.
.LONG TERM...(Monday night through Sunday)
Issued at 250 PM MDT Sun Apr 12 2020
Operational models and ensembles are in better agreement through
Friday with differences heading into the weekend. Overall, an
active weather pattern is forecast to continue across southern
Colorado with periods of Mountain snowfall along with rain and
snow over the lower elevations.
Monday night through Friday...a longwave trough is forecast to
remain over the central states this week with broad northwesterly
flow across Colorado. Several upper level disturbances embedded in
the flow will move across the region through the end of the week.
A quick moving upper wave will drop south across Colorado Monday
night into Tuesday morning. Models are in good agreement with a
decent shot of widespread snowfall across the area. Given the cold
temperatures in place, and the overnight arrival, snow is expected
across all of southern Colorado as the wave passes. Mountain
areas, and locations favored by northeasterly upslope flow will
likely see the greatest potential for accumulating snow. Totals
over the mountains of 1 to 4 inches are expected with locally
higher amounts possible. Less than an inch is expected over the
Plains. Models in good agreement with snow coming to an end late
Monday night into Tuesday morning, from northwest to southeast.
For Tuesday and Wednesday, northwesterly flow will favor
orographic snowfall over the Central Mountains. Minor
accumulations are expected. Tuesday will continue to be on the
cooler side with highs only reaching into the 40s across the
region. By Wednesday, the next upper level disturbance will be
approaching the area. Expect an increase in snow showers over the
Central Mountains, spread south and east into the Palmer Divide
Wednesday night.
The upper level disturbance will move across Colorado on Thursday
with a strong cold front dropping south across the Plains during
the morning. This will bring strong northerly winds to the area
and a drop in temperatures. Models in good agreement with Mountain
snowfall, while the Plains will be warm enough for rainfall. Snow
levels will likely fall to near 6 kft Thursday night before
precipitation comes to an end by Friday morning.
Friday through Sunday...models begin to diverge heading into the
weekend with an upper level low off the California coast. The GFS
is fast with the system, bringing it across the region by
Saturday. The ECMWF is slower and a bit further north with
precipitation holding off until Sunday. For now have low pops
across the area this weekend along with warmer temperatures.
Mozley
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 250 PM MDT Sun Apr 12 2020
KCOS and KPUB...
Unsettled weather to continue over these two taf sites during the
next 24 hours as cold cyclonic mid level flow continues over
Colorado for the next 24 hours and beyond. Low cigs will be likely
through the period as upslope surface flow continues, getting into
the MVFR and possibly IFR categories, especially during the
nighttime and early morning time periods. Cant rule out some
occasional light snow showers, especially KCOS. However any
accumulations should be light.
KALS
VFR next 24 hours. Breezy west winds will be possible tomorrow.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HODANISH
LONG TERM...MOZLEY
AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Springfield MO
628 PM CDT Sun Apr 12 2020
...00Z AVIATION UPDATE...
.SHORT TERM...(This evening through Monday)
Issued at 223 PM CDT Sun Apr 12 2020
A strong cold front extends from the KC metro south to near
Independence, KS and it will continue to shift east through our
forecast area through the early evening hours. Instability hasn`t
been very robust and has limited stronger convection. Some breaks
in cloud cover has allowed some limited instability over far
southwest MO with temperatures in the mid 60s. HRRR may be
overdone, but latest runs do show some mlcape around 1000 j/kg
close to the MO/AR ahead of the front as it moves through.
Marginal hail/wind risk is possible with the best potential south
of MO Hwy 60 through mid evening along/ahead of the front.
Much colder temperatures and strong winds will move in behind the
front, and this is well advertised with a wind advisory and freeze
warning. No changes are planned.
Winds will diminish late tonight into Monday with dry and very
cool conditions. We will probably need another couple of nights of
freeze/frost headlines this week but will take those one day at a
time. A thick overcast from a broad area of isentropic upglide
ahead of shortwave approaching from the west should keep
temperatures from free falling Monday night, but we may see some
sprinkles/flurries over the sw cwfa.
.LONG TERM...(Tuesday through Sunday)
Issued at 223 PM CDT Sun Apr 12 2020
Below normal temperatures are expected through midweek. A zonal
active pattern is expected, but there is quite a bit of spread in
sfc frontal positions over the central CONUS. The ops GFS spins
up a vigorous sfc low over the area Thu night, but it appears to
be an outlier. In general we will see moderating temperatures
late in the week with some degree of rain potential but confidence
on timing is low given the quick moving system in the zonal flow.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 524 PM CDT Sun Apr 12 2020
Area of showers is currently moving through the sites. Thunder
chances will likely remain closer to BBG. Ceilings will drop to
IFR and winds will switch to the northwest with gusts of 35-40kts
likely. Visibilities will also briefly drop to 2-5 miles in the
rain. Winds will remain gusty through the night. Conditions will
improve back to MVFR by early Monday morning.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory until 7 AM CDT Monday for MOZ055>058-066>071-
077>083-088>098-101>106.
Freeze Warning from 1 AM to 10 AM CDT Monday for MOZ055>058-
066>071-077>083-088>096-101>105.
KS...Wind Advisory until 7 AM CDT Monday for KSZ073-097-101.
Freeze Warning from 1 AM to 10 AM CDT Monday for KSZ073-097-101.
&&
$$
SHORT TERM...DSA
LONG TERM...DSA
AVIATION...Burchfield
Area Forecast Discussion
National Weather Service Las Vegas NV
503 PM PDT Sun Apr 12 2020
.SYNOPSIS...Waning shower and thunderstorm chances tonight becoming
mostly clear and dry by tomorrow morning. Dry weather is expected
Tuesday through Thursday with temperatures below normal Monday and
Tuesday increasing Wednesday and Thursday. Another system could
bring more shower activity and slightly cooler temperatures to the
area on Friday before warm and dry weather returns for the weekend.
&&
.EVENING UPDATE...
Majority of the showers and storms this evening have decreased in
strength as instability decreases across the CWA. Afternoon
convection just the help of the higher terrain to tap into an
otherwise impressive environment characterized by over 1000 j/kg of
CAPE and 30-40 kts of effective shear. The HRRR has done quite an
outstanding job depicting this evolution since yesterday which
prompted the increase in PoPs and thunder mention across the CWA
yesterday. Latest trends show the remaining activity quickly eroding
as it pushes southeast and have waned PoPs/QPF through 12Z to
reflect the latest HRRR trends. Still a low chance for minor
flooding where locations have already seen 0.5" or great across
southern Nevada and the Colorado River Valley.
Between 12-18Z tomorrow morning, skies will clear up quickly and
PoPs will drop to below mentionable levels to begin the upcoming
week of dry and mild conditions.
.SHORT TERM...tonight and Monday.
Shower and thunderstorm chances continue this evening across
portions of Mohave, Clark, Inyo, southern Nye and northeast San
Bernardino counties with chances primarily east of Las Vegas
overnight including the Colorado River Valley and Mohave County.
Windy conditions in the Western Mojave Desert early in the evening
is expected to decrease overnight. On Monday, shower chances
linger across portions of Mohave County with dry conditions and
below normal temperatures. Winds are forecast to increase late in
the afternoon Monday in northern Inyo County, across the Western
Mojave Desert and across the southern Great Basin.
Tuesday through Saturday...models have a dry northwest flow over
the area Tuesday and Wednesday which then transitions to westerly
ahead of an approaching upstream system moving south parallel to
the coastline. This system could bring another round of showers
to the area on Friday. Temperatures remain on the cool side of
normal Tuesday before warm back to normal or above Wednesday and
Thursday. Next weekend looks dry and mild with above normal
temperatures. However, there is some uncertainty with that and
this lowers forecast confidence.
$$
.AVIATION...For McCarran...Lingering showers will be possible
through 05Z this evening, but the chances of thunder at this point
is minimal. Winds have become variable across the valley with gusts
to about 20 kts at times. Ceilings should increase substantially
after 06Z with the remaining concern for Monday being whether
northerly winds will be strong enough to influence runway
configuration.
For the rest of southern Nevada, northwest Arizona and southeast
California...Continued potential for -TSRA and another several hours
of SHRA potential for KIFP/KEED through 08Z. Ceilings aoa 5-6kft can
be expected with brief visibility reductions as heavier showers move
through the terminals. After 08Z, expecting winds to be mostly light
with improving ceilings through Monday morning. Elsewhere, rain
should be over for KBIH/KVGT/KHND with improvement expected through
the overnight hours. KDAG winds are expected to increase and become
gusty through tomorrow morning.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Salmen
AVIATION...Gorelow
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