Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/27/20
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1026 PM EDT Sun Apr 26 2020
A low pressure system will slowly track northeast to
south of Long Island overnight. This system will continue to bring
widespread rain for valley locations and either snow or a rain/snow
mix to the higher terrain. Cloudy, cool, and damp conditions with
valley rain and mountain rain/snow showers will persist through
Monday, as low pressure gradually tracks just southeast of Cape Cod.
Drying is expected by Tuesday, as low pressure finally moves farther
away from our region and a small area of high pressure builds in
from the west.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Winter Weather Advisory now in effect until 5 am EDT MON for
northern Warren County...
Winter Weather Advisory in effect until 5 am EDT MON for
Winter Weather Advisory in effect until noon Monday for the
southern Greens of Bennington and western Windham Counties...
As of 1026 PM EDT...A persistent mesoscale snowband has
continued to impact portions of the northern Lake George Region,
northwest Saratoga Region, eastern Adirondacks, the west
central Mohawk Valley, northern Catskills and the Schoharie
Valley. We had a report of 4" in Bakers Mills/Johnsburg and snow
will continue to persist at least through midnight. We placed
northern Warren Co. into a Winter Wx Advisory.
Total accums of 2-6" are possible across the higher terrain of
Warren County. We are thinking 1-2" is possible in portions of
the western and central Mohawk Valley, except we have had some
reports in extreme southwest Montgomery county closer to 1000 ft
of 5". Therefore, some isolated higher amounts are possible. We
still have totals of 3-7" are likely in Schoharie County. 2-5"
in the southern Adirondacks foothills /northern Fulton Co./ and
southern Hamilton County, and the eastern Catskills.
The activity south and east of the mesoscale band has been
intermittent and showery with a dry slot between the coastal
wave south of Long Island and the primary wave over the Mason
Dixon Line evident on the GOES-16 water vapor imagery. Again,
the heavy pcpn rates combined with wet bulb/dynamical cooling
from the mesoscale band caused the light to moderate snow
tallies in the west-central Mohawk/northern and eastern
Catskills, foothills of the southern Adirondacks, the Lake
George northern Saratoga Region. The mesoscale snowband is tied
to area of low to mid level frontogenesis /H850-H700 layer/ that will
continue to weaken based on the 3-km HRRR over the next few
hours. There is slight a chance southern VT above 1500 ft could
get a quick burst of 2-6" of snow above 1500 feet, so we will
leave the Advisory going there.
SLR continued around 4:1 to 7:1 in the higher terrain, which
will be a wet consistency. Snow may mix in down to around 1000
ft with a coasting to perhaps an inch or so in some spots.
Valley locations will likely just see plain rain tonight outside
of the western and central Mohawk Valley. Some breaks in the
precip may occur after midnight, as the coastal cyclone tracks
southeast of Cape Cod. Still, most areas north of Albany will at
least experience occasional precip much of the night.
Northeast winds will become quite gusty across the favored
higher terrain areas of the southern Greens and Berkshire, as
low level winds increase and peak overnight. Will continue to
mention gusts of 30-40 mph in these areas, with generally 20-30
mph gusts elsewhere.
Low temps will be mainly in the 30s, with some upper 20s on the
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
The surface cyclone will continue to track northeastward from a
position just south and east of Cape Cod on Monday. The upper
level pattern will be rather chaotic, with a large closed
circulation over the region, with several short waves rotating
around the main gyre. Relatively steady precip (rain/snow) will
occur over most higher terrain areas, with rain likely in the
valleys. Thermal profiles should be slightly "warmer", as the
forcing and precip rates will be weaker. So not much additional
snow accumulation is expected at elevations below 1500 ft. By
afternoon, any accumulations should be confined to the mountain
peaks. It will remain cloudy/cool through the day, with highs
only in the mid/upper 40s in valleys and mid/upper 30s in the
higher terrain. Winds will shift to the north.
Some lingering light rain/snow showers will be possible Monday
evening associated with a weakening trough axis and wrap-around
moisture, but the bulk of the precip will finally start to
diminish. The upper trough starts to shear out, while a small
surface ridge builds in late Monday night into Tuesday morning.
Temps will remain below normal.
Drying conditions in store for Tuesday, as the surface ridge
moves across the region, with a light northwest flow. There
should be at least a mix of sunshine and clouds for much of the
day, so temps will respond by warming well into the 50s in
valley locations. Upper level ridging will develop Tuesday
night, which will keep dry conditions in place. The air mass
will remain cool, with low temps in the upper 20s to upper 30s.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Upper level ridging will be departing to the east on Wednesday
as a large upper level low over the Midwest starts to approach.
Although the morning will start off dry and quiet, sky cover
will be quickly increasing on Wednesday. There continues to be
some uncertainty regarding the exact speed of this system and
when some initial warm advection precip may begin across the
area. Although we do have some CHC POPs for western areas by
afternoon, it may take until Wed evening or night for rain to
begin across the entire area. Temps will be a little below
normal, but still comfortable, with valley highs well into the
With a strong southerly low-level jet (about 50 kts at 850 hpa)
ahead of the advancing storm system, there should be a period
of steady rainfall, most likely for some point between late Wed
night through Thursday evening. Some moderate to locally heavy
rainfall can`t be ruled out, especially across the higher
elevations, where upslope flow will enhance rainfall. With
plenty of mild air, both at the surface and aloft, p-type will
be all plain rain. Daytime temps should be in the 50s for most
spots, with upper 30s to mid 40s at night.
As the best isentropic lift shifts away, the steadiest rainfall
will end for later in the week. However, plenty of lingering
clouds and showers will continue for Thursday night through
Friday, as the slow moving upper level low passes over the
region and cyclonic flow remains in place. Will keep POPs fairly
high for Thursday night into Friday with more rain showers.
Lingering clouds and a shower or two may continue into Saturday
morning, otherwise, gradual clearing is expected by Saturday
afternoon as the upper level disturbance moves away and drier
air works into the region. Still some uncertainty for the
remainder of the weekend with zonal flow in place, so will keep
some low POPs in place. With some sun returning and milder temps
aloft, max temps look to be in the mid 50s to mid 60s across
the region, with overnight lows in the 40s.
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
A secondary low pressure system will move from coastal southern
NJ this evening to near Cape Cod by daybreak tomorrow, and then
move slowly east to northeast towards Nova Scotia during the
Expect cigs/vsbys to continue to fall to MVFR levels at
KGFL/KALB/KPSF/KPOU early this evening with periods of rain. The
cigs/vsbys may briefly lower to IFR levels at KPOU/KPSF/KGFL
prior to 06Z/MON. For KALB, we have kept cigs/vsbys mainly MVFR
until close to 08Z/MON when some IFR cigs may develop. Some snow
may briefly mix with the rain at KPSF overnight.
Widespread low MVFR/IFR conditions are likely prior 12Z-14Z/MON,
until the pcpn lets up and maybe spotty. We could even see a
brief lull in the rain or shower activity until noon or so. We
tried to raise conditions to MVFR levels in the late morning or
early pm. Some rain or showers will redevelop due to the upper
low and the coastal cyclone slowly moving northeast of Cape Cod.
We maintained cigs 1.5-2.5 kft AGL in the afternoon with vsbys
in the 4-6SM range.
The winds will be north to northeast at 8-15 kts tonight with
some gusts 20-25 kts at KALB/KPSF/KGFL. The winds will continue
to be northerly at 8-13 kts during the late morning into the
afternoon with some gusts around 20 kts.
Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: Low Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Moderate Operational Impact. Chance of SHRA.
Wednesday Night: High Operational Impact. Definite SHRA.
Thursday: High Operational Impact. Breezy. Definite RA.
Thursday Night: High Operational Impact. Definite SHRA.
Friday: High Operational Impact. Likely SHRA.
A low pressure system will slowly track eastward across the
Middle Atlantic region into this evening, before emerging off
the New Jersey coast tonight. This system will bring widespread
rain for valley locations and either snow or a rain/snow mix to
the higher terrain. Cloudy, cool, and damp conditions with
valley rain and mountain rain/snow showers will persist through
Monday, as low pressure gradually tracks just southeast of Cape
Cod. Drying is expected by Tuesday, as low pressure finally
moves farther away from our region and a small area of high
pressure builds in from the west.
Relative humidity will increase to around 90 to 100 percent
tonight, and will only drop to around 70 to 85 percent on Monday
with cool/damp conditions persisting. Relative humidity will
increase to between 80 and 95 percent Monday night.
Winds tonight will be northeast around 10 to 20 mph, with some
gusts of 30 to 40 mph in the higher terrain of the southern
Green mountains and Berkshires. Winds on Monday will be
northerly around 10 to 15 mph, becoming northwest at 5 to 10 mph
Two storm systems are expected to bring widespread
precipitation to eastern NY and western New England this week.
The first will be a long duration event with widespread rain
this afternoon into tonight. Rain will change to accumulating
snow for elevations above 1500 ft. Rain showers and rain/snow
mix in the higher terrain continue into Monday. Total
precipitation for this event will range between 0.75 and 1.50
inches. Whiles rivers rises will occur, flooding is not
anticipated at this time.
After a brief break for dry weather mid-week, a moisture-rich
system will bring another long duration event to eastern NY and
western New England Thursday into Friday. Guidance continues to
signal that the system will pump a plume of moisture out of the
Gulf of Mexico and the Atlantic and direct it into the
Northeast, leading to a period of steady (perhaps heavy)
rainfall during this time. Widespread rainfall amounts of 1 to 2
inches are possible with locally higher amounts due to terrain
enhancements and instability. Given that soils will likely
already be relatively saturated from the earlier event, rivers
should respond once again.
Current MMEFS indicates some river points may approach minor
flood stage later this week, but there is a low confidence for
any river flooding at this time. Will have more specifics as the
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.
NY...Winter Weather Advisory until 5 AM EDT Monday for NYZ042-047.
VT...Winter Weather Advisory until noon EDT Monday for VTZ013-014.
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
648 PM CDT Sun Apr 26 2020
Issued at 245 PM CDT SUN APR 26 2020
Surface ridge solidly in place over the forecast area through the
first half of Sunday, going into the afternoon and evening hours.
This has caused very light and somewhat variable winds across the
area with ample sunshine. Slowly, but surely that ridge will
continue its trek eastward, allowing for southerly return flow into
the immediate area. Expect southwest winds to prevail going into the
evening and overnight hours tonight. The bigger forecast concern for
the next 12-24 hours will be the prospects for at least scattered,
if not widespread showers later tonight. The mechanism for the
thunderstorm activity tonight is apparent on radar across eastern
Kansas and western Missouri, where decent isentropic ascent along
the 300 and 305K surface are providing just enough ascent to form
some clouds and some high-elevation showers. Forecast soundings
indicate a very dry layer of air blow the cloud bearing layer where
the light precipitation is being formed. While it`s not completely
inconceivable that some rain drops survive that dry layer below 10
kft most will evaporate, so accumulating rain is not likely through
the remainder of the daytime hours. That may change as we go into
the overnight period, as the isentropic ascent becomes a little more
pronounced as a low level jet noses in. With not much antecedent
moisture to work with, main source of moisture will be whatever
advects into the area within that low level jet regime. This will
severely limit the MU CAPE to at most 500 J/kg. Despite ample shear
the instability should be modest enough to keep any of the elevated
showers overnight sub-severe. While Hi-res models, namely the HRRR
seems to indicate most of the convection to occur just east of the
KC Metro, it`s very possible that with the better lift around or
maybe even just west of the KC metro that there could be some of
those scattered storms over the metro tonight with some rumbles of
thunder possible through the morning hours. For Monday, clouds may
stick around for most of the day, as the cloud debris from the
overnight activity slowly clears out. The clouds may be reinforced
by a shortwave trough gliding through the area during the mid to
late morning hours. Despite the cloudiness, temperatures on Monday
should remain nice and warm with the southerly winds advect
warmer/moister air into the area.
Much uncertainty still clouds over the potential for strong to
severe storms on Tuesday. Synoptic scale operational models have
indicated an early arrival of a cold front impacting a deep warm
sector on Tuesday. It`s possible this cold front will arrive a bit
later in the day, in which case even 6 hours later would result in
more destabilization and a more northward/westward expansion of the
impacts of these potentially strong storms. Latest run of the NAM
does hint at that being the case as it`s cold frontal position at
18z on Tuesday is currently west of the forecast area, indicating a
push through the area at a more prime time for potentially severe
weather. The 12z ECMWF appears to be following suit, so Tuesday will
still need to be watched for a more organized severe weather day for
at least a portion of the forecast area if not the entire forecast
area, including the KC Metro.
Cold front passes through the area by Wednesday, making for what
should be a quiet Wednesday and Thursday. Northwest winds on
Wednesday may be rather gusty, depending on how deep we can mix,
there would be a chance to see some 30 to 40+ mph surface winds on
Wednesday as the surface ridge moves in. Beyond that time period,
going into the late part of next week there is some support for a
reloading warm sector into the forecast area. That may portend
perhaps an uptick in convective weather going into the extended
.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 638 PM CDT SUN APR 26 2020
High based showers are currently moving through eastern Kansas and
western Missouri early this period. Little if any rain is making
it to the surface and much of the activity will remain virga due
to much drier air near the surface. The 850mb low level jet will
increase this evening resulting in the development of scattered
showers and thunderstorms from about 06-12Z, but may continue
through 15Z. A shortwave trough moves through during the early
afternoon hours, but the bulk of the precipitation from this wave
is expected to stay south of the terminals. Southerly winds will
pick up after 12Z and could see some gusty of 20-25 kt from mid to
late morning continuing into early afternoon.
Area Forecast Discussion
National Weather Service Grand Forks ND
953 PM CDT Sun Apr 26 2020
Issued at 953 PM CDT Sun Apr 26 2020
Seeing an uptick in moderate radar returns over eastern ND as
activity spreads east, with a couple lighting flashes picked up by
GLM just southwest of our CWA. Activity remains scattered, and
outside of where 35-45 dbz returns are most activity had been
virga due to a good sub cloud dry layer in place across our
region. Upstream trends to the west indicate weakening, with a
potential subsident axis on satellite likely associated with PV
anomaly immediately behind trough axis. We still expect scattered
showers/isolated storms to track east with activity diminishing
in eastern ND around midnight, and possibly increasing in coverage
ahead of trough axis in north central MN. Amounts have been enough
to wet surfaces, but overall no any major impacts. Could see
potential for 0.1-0.25 in northwest MN before it exits at
UPDATE Issued at 656 PM CDT Sun Apr 26 2020
Returns on radar would indicate numerous light rain showers,
however most basins are high and there are only a few pockets
where rain is reaching the surface in our area. There is still
instability show on RAP analysis (MUCAPE around 250 J/KG), but so
far most lighting activity has remains well north of the
International Border. CAMs (and forecast) timing matches well with
current radar returns, however it may be overdone regarding
actual threat of measurable precip early this evening. As this
activity spreads east tonight there is still an indication that it
will pick up in intensity with measurable chances increasing in
north central MN. For now I made adjustments to near term timing,
but held off on more substantial chance beyond that.
.SHORT TERM...(This evening through Monday)
Issued at 307 PM CDT Sun Apr 26 2020
Little impacts wrt to the weather in the short term. Frontal
passage this evening will bring some scattered shower activity to
the area with possibly some embedded thunder with MUCAPE up to 500
J/kg. Model solns continue to depict coverage increasing as the
precip moves into the MN portions of the area this evening and
into the overnight. Amounts will be on the light side with up to a
tenth of an inch or so with the heaviest showers. Also expecting
some evaporation with dry near surface layer causing some virga.
Monday will see west winds develop behind the front and sunny
skies allowing for temps to reach into the mid and upper 60s. A
few locations may see their first 70 degree day of the warm
season as the quick moving surface ridge axis pushes across the
.LONG TERM...(Monday night through Sunday)
Issued at 307 PM CDT Sun Apr 26 2020
This forecast period will be active with multiple upper waves moving
through or near the Northern Plains. The first wave will lead to
rain chances Monday night into Tuesday night. The main source of
lift will be a surface low passing to the south across northern Iowa
or southern Minnesota. For this reason the highest rain totals are
expected over southeast North Dakota and west central Minnesota.
Some instability may also be present in this same area to allow for
thunderstorms. Instability will not be high enough and there is not
likely to be enough shear for strong to severe storms in this area
with CAPE under 500 J/kg and bulk shear under 20 knots. The
confidence in rain is high, but the exact amounts are still somewhat
uncertain due to spread in both ensemble and deterministic guidance.
A break in the activity for Wednesday and Thursday with only a few
rain showers possible. Friday looks likely to be the warmest day of
the year so far with high temperatures in low to mid 70s for most,
some upper 60s still more likely in north central Minnesota. With
this heat comes more potential for CAPE, but a relatively dry
environment looks to keep LCLs high and CAPE values low. There is a
fair to moderate amount of shear around, but with out much
instability strong storms are not as likely to form. If there is a
chance something could form it would be along the front moving
across the Northern Plains late Friday. A period of ridging looks
most likely for the next weekend leader to quieter weather.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 656 PM CDT Sun Apr 26 2020
VFR conditions are expected to prevail through the TAF period
across eastern ND and northwest MN, with main aviation impact from
showers moving west to east across the region. We also can`t rule
out an isolated thunderstorm, but so far coverage looks to be very
low/threat minimal. Southerly winds 10-15kt should continue to
decrease and eventually shift to the west late tonight/Monday
morning remaining near or below 10kt for most locations. A few
daytime gusts to 20kt can`t be ruled out Monday (mainly north of
River point flood warnings continue across portions of
the region. Refer to the latest flood warnings and statements for
detailed information on specific locations.