Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/22/19
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1018 PM EDT Thu Mar 21 2019
.SYNOPSIS...
Low pressure, over Delaware this evening, will strengthen and
slowly move northeast to near Boston by Friday Afternoon.
Impacts from this noreaster will be rain, snow and gusty winds.
Although valley areas should see only a light accumulation of
snow, some significant snow totals are possible across the hills
and mountains. Behind the storm, it will remain cold and
blustery for Saturday, before milder temperatures return for
Sunday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 1018 PM EDT...radar shows large hole in precipitation
shield covers southern half of forecast area. Updated POPs to
reflect this. Web cams still show snow falling in higher
terrain where temps are between 32-34 degrees F. Next round of
precipitation moves into area from the south after 03-04Z. Based
on latest model output, lowered the rain and snow mix to about
500ft MSL towards daybreak. There could be a slushy accumulation
of snow tomorrow morning outside of the lowest valley locations.
Snow amounts increase for tonight across northern Washington,
northwestern Saratoga, southeastern Hamilton, northern Fulton
County and the higher elevations of the eastern Catskills and
southern Green Mountains based on latest model output.
Previous...
Low pressure is located over eastern Virginia and this storm
will be deepening this evening into tonight as it lifts
northeast along the mid Atlantic coast. This low pressure is
quickly strengthening as the result of two separate pieces of
upper level energy that have phased over the mid-Atlantic and
will be even further strengthening by yet another northern
stream shortwave moving into the region on Friday.
A strong S-SE low-level jet (850 hpa v wind anomalies are about
2-3 STD above normal) is allowing for a period isentropic lift
for late this afternoon into early evening. An area of steady
light precipitation is lifting northward from the Catskills
across the Mohawk Valley and Capital Region. Most of this precip
is rain, although some wet snow is mixing in with the rain for
areas above 2000 ft in elevation (as seen in NYS Mesonet cams).
Hi-res model guidance (such as the 3km HRRR and NAM) show this
band lifting northwest this evening and rotating into central
New York for tonight. This should allow for a brief break in the
steady precip from the Capital Region on south and east for
later this evening.
However, steady precipitation will return to the whole region
from south to north for late tonight (midnight onward), as the
low pressure continues to lift northward and strong
frontogenesis sets up south of the area. Model soundings suggest
most of the area should be starting off as rain, as the entire
profile looks to be above freezing under 825 hpa. However, by
late tonight, temps aloft should be cooling, as both dynamical
cooling processes and the approaching cold pool aloft will allow
temps to drop off aloft. This should change precip over from
rain to snow across the higher terrain towards daybreak Friday.
Temps will be starting out this evening in the mid 30s to mid
40s and will be lowering into the low to upper 30s by late
tonight.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Complex storm will be ongoing on Friday as low pressure
continues to strengthen as it lifts northeast along the coast.
The low pressure will be moving from NJ early in the morning
towards eastern Massachusetts by afternoon and reaching eastern
Maine by evening.
Although the main surface low will be moving away from the area
through the day, there still looks to be fairly steady
precipitation through much of the day, as the upper level
shortwave moving in from the Great Lakes will be phasing with
upper level shortwave lifting up the eastern seaboard. This
should provide plenty of lift and the cyclonic flow will keep
enough moisture in place as well.
With temps aloft continuing to cool, precipitation type will be
tied to elevation and precip intensity. High terrain areas
(mainly above 1000 feet) look to see mainly snow on Friday,
while valley areas will see primarily rain. It`s possible that
some brief burst of snow are possible even in valley areas
through the day within heavier burst of precipitation, so p-type
may be changeable at times. Temps will generally be in the 30s,
although the immediate Hudson Valley may reach into the 40s
during periods of light or no precipitation.
By Friday night into Saturday morning, temps (both aloft and at
the surface) will be continuing to cool off and p-type should
be changing to just snow across the entire region. However,
coverage of snow will start to be limited to upslope and lake
enhanced areas across the high terrain (especially after
midnight Friday night). Snow may especially linger across the
northern Taconics, southern Greens and northern Berkshires into
early Saturday, as these areas generally see persistent
snowfall with the upslope flow on the backside of the departing
storm system. Any lingering snow looks to end by midday on
Saturday. By this time, about 5 to 10 inches are possible across
the high terrain will locally 10-14 inches for the Rensselaer
Plateau and across the southern Greens. While most valley areas
(under 5000 ft) should only see 1 to 3 inches, some of the
outlying hillier areas (about 500-1000 feet in elevation) could
see 2 to 6 inches of snowfall.
Temps fall into the teens and 20s across the region for Friday
night. Temps during the day on Saturday should only reach the
mid 20s to low 40s for the region.
With the cooling temps aloft, good mixing is expected up to
about 850 hpa and some gusty winds will be picking up.
Based on model soundings, northwest winds may gust 30 to 45 mph
(and possible even a few higher gusts as well) for Friday night
into Saturday.
Although there will be plenty of clouds to start on Saturday,
there should finally be some breaks by midday and into the
afternoon. Even further clearing looks to occur Saturday night,
as high pressure starts to approach from the west, with temps
falling into the teens and 20s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
A rather strong arctic front moves through Sunday night into early
Monday, then it appears an extended period of dry weather with a
moderation in the temperatures.
12Z Global Models are in rather good agreement with the overall
synoptic set up heading into the long term forecast period as
progressive trough will slowly be replaced by rising heights along
the eastern seaboard. First, a dry start to Sunday as narrow ridge
slowly moves off the mid-Atlantic coastline as we will endure yet
another arctic frontal boundary that is set to move across the
region Sunday night. Now, trends in the model RH and QPF fields
continue to diminish as this arctic boundary appears to not only be
limited in moisture, but also faster timing which limits moisture
entrainment from developing Central Plains storm system. So with
this forecast update we will reduce PoPs a bit with a chance of
light rain/snow. By Monday afternoon, the arctic boundary is
forecast to be well south of the region as dry air advection is
underway with a brisk northwest wind.
Tuesday through Wednesday, high confidence with large area of high
pressure of 1030-1035mb moves across the region. This will keep the
weather tranquil with partly cloudy to mostly clear skies and light
winds. Late March sun angle and slowly rising heights and thermal
column moderation should allow for seasonable temperatures to be
felt by the mid-week period. The next potential for wet conditions
may not be until next weekend.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Showers have become less numerous with southeasterly winds
allowing ceilings to improve with VFR cigs except at KGFL which
is currently MVFR. Some improvement possible at KGFL before
next round of steady precipitation moves in bringing MVFR/IFR
conditions to the TAF sites.
Rain may mix with snow for a period at ALB and PSF 22/09Z -
22/15Z which could lower visibilities down towards 1-2SM with
GFL potentially becoming all wet snow for a period. Ceilings
should improve some by late morning trended back towards MVFR.
However, a round of snow accompanied by gusty northwest winds
could begin near the end of this TAF period around 22/23Z.
The winds will generally be from the northeast overnight ranging
from 5-15 kts. The winds will become northwest towards after
22/16Z.
Low-level wind shear may increase below 2 kft AGL at KGFL, KPOU
and KPSF after 06Z/FRI.
Outlook...
Friday Night: High Operational Impact. Windy. Likely RA...SN.
Saturday: Moderate Operational Impact. Windy. Slight Chance of
SHSN.
Saturday Night: Low Operational Impact. Breezy. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Moderate Operational Impact. Chance of RA...SN.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
&&
.FIRE WEATHER...
A coastal storm will bring rain and snow to the region for
tonight through early Saturday. High terrain areas will see a
moderate to heavy snow accumulation, which will add to the
snowpack already in place. This will help limit fire weather
concerns for the time being across the region.
&&
.HYDROLOGY...
No hydrologic issues are anticipated through early next week.
A slow moving coastal storm will bring rain and snow to the
region for tonight through early Saturday. About 0.75 to 1.25
inches of liquid equivalent is expected with this storm, with
much of this being in the form of snow across the higher
elevations.
The combination of high terrain snowfall and chilly temperatures
will allow for only limited immediate runoff with this storm
system. While some small rises are possible on rivers and
streams, no flooding is anticipated at this time. Dry weather is
then expected behind the storm for later Saturday into Sunday.
Just some scattered light rain or snow showers are expected on
Monday with the next frontal system.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory from 2 AM Friday to noon EDT Saturday
for CTZ001.
NY...Winter Weather Advisory from 2 AM Friday to noon EDT Saturday
for NYZ048-051-058-061-063.
Winter Storm Warning from 2 AM Friday to noon EDT Saturday for
NYZ032-033-038-042-047-054-082.
MA...Winter Weather Advisory from 2 AM Friday to noon EDT Saturday
for MAZ025.
Winter Storm Warning from 2 AM Friday to noon EDT Saturday for
MAZ001.
VT...Winter Storm Warning from 2 AM Friday to noon EDT Saturday for
VTZ013-014.
&&
$$
SYNOPSIS...SND/Frugis
NEAR TERM...SND/Frugis
SHORT TERM...Frugis
LONG TERM...BGM
AVIATION...SND
FIRE WEATHER...Frugis
HYDROLOGY...Frugis
AREA FORECAST DISCUSSION
National Weather Service Binghamton NY
1052 PM EDT Thu Mar 21 2019
.SYNOPSIS...
A complex and slow moving coastal system will spread a variety
of weather across the area into early Saturday. Rain will fall
this evening, but as colder air moves in the rain will
gradually change to snow late tonight and continue through
Friday night. Significant snowfall is expected over the higher
elevations north and northeast of Binghamton, but much of the
area will see at least some accumulating snow. Drying out with
milder weather for the second half of the weekend.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
Mesoscale Update #2 10:30 pm:
Trends in the mesoscale modeling has been to shift the
previously mentioned snow band expected to setup overnight a
little further east. Precipitation amounts have been increased
across northeastern PA into the western Catskills. As a result,
higher elevations through most of NE PA stand to get a few
inches snow with some spots in northern Wayne county of locally
6-8 inches in the highest elevations. Headlines were expanded a
little further south with this update.
Mesoscale update #1 7:30 pm:
Mesoscale modeling continues to have variance with where a
mesoscale band of moderate to perhaps heavy snow sets up
overnight. The latest HRRR and 18Z NAM Nest trended east (Wayne
county northeast into the western Catskills) with the 18Z RGEM
and RAP run further west (back toward the Binghamton to Rome
areas). This leads to a considerable amount of uncertainty with
the location of this band. Within the band dynamical cooling is
likely to occur leading to a change from rain to snow with
moderate to perhaps heavy precipitation rates for a time
overnight. Looking at FGEN forcing on the NAM, they are
indicating forcing in place for snowfall of 2 inches per hour in
localized spots under the band for a time overnight. We
continue to blend the two solutions for now but narrowed the
goal posts a bit. This lowered snow totals a bit from Syracuse
into the Finger Lakes but kept totals rather steady elsewhere
given snow ratios still look to be around 6-8:1 overnight.
400 PM Update...
Main concern in the near term period will be a powerful, slow
moving coastal system that will bring rain changing to a period
of heavy, wet snow for parts of the forecast areas. Periods of
snow and blowing snow continue into Friday night, mainly across
central NY. Upgraded the winter storm watch to a warning for
Oneida, Onondaga, Madison, Cortland, Chenango, Otsego and
Delaware counties. A winter weather advisory is also now in
effect for Seneca, Cayuga, Tompkins, Tioga, Broome, Sullivan,
northern Wayne, Susquehanna and Bradford counties. Generally 5-9
inches in the lower elevations, with 9-15 inches over the
higher elevations for the warning areas. 2 to 6 inches, with
locally up to 8 inches for the advisory areas...again with the
higher end totals over the hilltops. Outside of the
warning/advisory areas expect minimal snow accumulations of just
an inch or two possible. This is a lower than normal confidence
forecast, with the potential for much lower snow amounts if it
remains even slightly warmer or if the coastal low tracks
further east. Be sure to check back for the latest forecast and
winter headline updates.
Steady rain will overspread the rest of the area by sunset.
Precip type still looks to be all rain just about everywhere
(except perhaps the highest peaks of the Catskills/Poconos,
where wet snow could occasionally mix in) through sunset.
Temperatures steady in the upper 30s to lower 40s through the
day...with some mid to upper 40s possible across the northern
Finger Lakes and Syracuse area where it`ll stay dry longer.
Southeast winds increasing to between 8-15 mph by afternoon with
a few higher gusts over the higher terrain. Rainfall amounts
through sunset will range from about 0.75-1" south of I-84 in NE
PA, 0.33-0.50" across the northern tier of PA, around quarter
inch for the NY southern tier, and less than a quarter inch
further north.
Latest satellite and radar trends show the developing coastal
low over the Delmarva region, with a well developed baroclinic
leaf and comma head evident on IR imagery. There are a few
lightning strikes being observed off the NC/VA coast, and the
next piece of energy is moving into the Ohio Valley (also with a
few lightning strikes). Regional MRMS shows a strong influx of
moisture coming in off the Atlantic from the Delmarva north to
NJ and east central PA. The precipitation is beginning to pivot
in a developing deformation band across north-central Virginia.
The latest 12z and near term mesoscale guidance has trended
slower, stronger, a touch colder and further west with the
coastal low for tonight into Friday. Although the guidance is
all in fairly good agreement there are still subtle differences
in the track, strength and thermal profiles...which will most
certainly have a large impact on exact snow amounts across our
region. Leaned the forecast toward the NAM/HRRR and ECMWF along
with WPC guidance. Overall the trend is for a heavier
deformation band of rain, changing to snow after midnight
tonight lingering into the early to mid morning hours Friday.
Initially there is not much in the way of cold air advection
tonight, so the transition to snow will be mainly due to dynamic
cooling as the surface low tracks from near Salisbury MD to
west-central Long Island overnight. The surface low now looks to
deepen to around 985-990mb by 12z Friday, with a closed 700mb
and 500mb low nearly vertically stacked over it.
A strong easterly low level jet around 35-45 kts will be
present along the NYC/NJ and will again aid in transporting a
plethora of Atlantic moisture back into the east-central portion
of our forecast area. A strong area of mid level frontogenetical
forcing will be present along and east of the I-81 corridor
from about 2am to 10am Friday morning....and this is where the
rain is forecast to change over to heavy wet snow...first over
the higher elevations between about 11 PM and 2am, then in the
lower elevations by 1am to 4am. As is usually the case even the
near term guidance is struggling with exactly where this heavy
deformation band will set up and pivot. With a low track right
along the NJ coast to just east of NYC...climatology favors this
band to set up right along I-81 and points east....there will
likely be a sharp cutoff in the steady snow by 8am Friday from
near Syracuse to Owego and Towanda. This snow band only very
slowly shifts off to the north and east by late morning...with a
dry slot over the western Finger lakes and central southern
tier. Surface temperatures peak late morning or midday Friday,
in the low to mid-30s across central NY, and 35-43 across
northeast PA.
By late afternoon, as the entire system becomes vertically
stacked near Portland Maine, another round of significant wrap
around snow will redevelop, moving in from north to south and
continuing to pivot around the nearly stationary low pressure
system well into the overnight hours Friday. Temperatures aloft
and the surfaces will fall rapidly Friday evening and
night...reaching the lower 20s. The snow will become fluffier in
nature as snow to liquid ratios reach 15:1. Northwest winds
continue to increase Friday night with gusts up to 40 mph,
especially over the higher elevations. This will cause areas of
blowing and drifting snow to develop...mainly in the advisory
and warning areas. The highest snow amounts Friday night area
forecast to be north of the NY southern tier...up across the
northern Susquehanna region and NY Thruway corridor. There could
be a local minima in snowfall near the Mohawk Valley, as the
northwest flow downslopes off the higher Tug Hill plateau
region. Only scattered snow showers or flurries are expected
across the Susquehanna, Wyoming and Delaware river valley
regions in NE PA. The lake enhance snow showers gradually taper
off from west east late Friday night and early Saturday
morning.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
Saturday...Quiet weather returns to the region during this
period after some lingering light snow showers diminish across
the northern and eastern forecast area. The vertically stacked
low will be well northeast of the region by afternoon, in the
Canadian maritimes, allowing skies to become partly/mostly
sunny. Highs will range in the lower to middle 30s across
central New York with mid 30s to around 40 in northeast
Pennsylvania.
Saturday night/Sunday...High pressure will build into the mid
Atlantic region during the period making for a mainly clear
night and mostly sunny Sunday. Highs on Sunday will rebound
into the upper 40s to mid 50s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
An upper level trough will control our weather and keep us cold and
unsettled through early next week, then a developing ridge will push
toward the Ohio Valley by midweek.
Sunday night and Monday...A front dropping into Northern NY will
push a mix of snow and rain showers into NY and PA. Temperatures on
Monday will range from the upper-30s over the Finger Lakes and
Western Mohawk Valley to around 50 near Wilkes Barre.
Monday night...Dry, cold air will drop out of Canada and knock
temperatures down into the teens and lower-20s. A few light snow
showers will remain possible.
Tuesday through Thursday...High pressure will yield quiet weather
during the middle of next week. Temperatures will start much below
normal on Tuesday with highs in the 30s and increase into the 50s by
Thursday.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Mainly IFR and MVFR throughout the TAF period. Periods of rain
will continue throughout the evening with ceilings and
visibilities staying mainly MVFR but bouncing to IFR at times.
Overnight, the rain is expected to mix with and change to snow.
A period of moderate to perhaps heavy snow is currently
possible at KRME and KBGM as well. This would lead to the
lowest restrictions into the IFR and LIFR range if it
materializes. A lower possibility of a period of moderate to
heavy snow is present at KAVP, KELM as well at KITH. The timing
of the changeover from rain to snow along with any moderate to
heavy snow would be from 7-11Z Friday give or take a couple of
hours.
During the day Friday, winds will become gusty from the
northwest with top gusts around 25 knots. Also periods of snow
with MVFR to IFR conditions will likely continue throughout most
of the day.
Outlook...
Friday night through Saturday...Intermittent restrictions from
snow showers, especially the NY terminals. Gusty northwest wind.
Saturday night through Sunday night...Mainly VFR.
Monday...Possible restrictions in snow or rain.
Tuesday...Mainly VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory from 2 AM Friday to 8 AM EDT Saturday
for PAZ038-039-043-044-072.
Winter Storm Warning from 2 AM Friday to 8 AM EDT Saturday for
PAZ040.
NY...Winter Weather Advisory from 2 AM Friday to 8 AM EDT Saturday
for NYZ016-017-025-055-056-062.
Winter Storm Warning from 2 AM Friday to 8 AM EDT Saturday for
NYZ009-018-036-037-044>046-057.
&&
$$
SYNOPSIS...MJM
NEAR TERM...MJM/MWG
SHORT TERM...RRM
LONG TERM...DJP
AVIATION...MWG/RRM
Area Forecast Discussion
National Weather Service Denver/Boulder CO
929 PM MDT Thu Mar 21 2019
.UPDATE...
Issued at 929 PM MDT Thu Mar 21 2019
No changes needed at this time. This evening a band of snow
showers brought what looks like a quick inch of snow in South
Park. This is lifting NNE and weakening as it approaches I-70, but
there are more showers developing down around Salida that should
take a similar path. There`s a bit of a dry slot further west, but
not sure this will move much. Current forecast of light snow
showers with some decrease later tonight still looks alright.
These showers will try to drift a bit off the mountains but will
be fighting low level dry air, so while a few sprinkles are
possible later tonight on the plains it shouldn`t be much. Gradual
moistening on tap for Friday morning with the main lift and
destabilization in the afternoon, which seems to be well covered.
&&
.SHORT TERM...(This evening through Friday)
Issued at 321 PM MDT Thu Mar 21 2019
Current satellite imagery shows an elongated upper level trough
stretching across the Desert Southwest toward the Four Corners
area. Moisture and instability was leading to shower and
thunderstorm development to our west. The main batch we`ll have to
contend with tonight is the current band of showers and
thunderstorms stretching from near Grand Junction into northwest
New Mexico. This band, fairly well handled so far by the HRRR and
NAMNest, is advertised to reach the northern mountains 8-11 PM. We
have therefore bumped up PoPs in this time frame when we could see
a quick inch of slushy snow over the mountains, with up to 2 or 3
possible on some slopes around the Mosquito Range.
On the plains, the low levels are still fairly dry and we have
deep southerly flow sheltering us, so mainly virga is expected. We
can`t rule out a couple showers due to mid level instability, so
we`ll maintain a slight chance of precipitation.
On Friday, shower coverage will expand over the entire forecast
area by afternoon as the upper level low begins to reorganize over
the Colorado/New Mexico border, and we destabilize further with
daytime heating. CAPE values increase to 200-500 j/kg, so will
mention isolated to scattered thunderstorm coverage as well. A
couple thunderstorms may produce small hail, especially over
Lincoln county where CAPE may approach 800 j/kg by late afternoon.
Snow levels will hover near 7000-8000 feet most of the day, with
the lower levels west of the Front Range. Accumulations of 2 to 4
inches can be expected above 9000 feet during the bulk of the snow
showers during the afternoon. Snow may be quite heavy at times
due to the convective nature of the snow, so despite the
relatively mild temperatures road impacts will be possible along
the I-70 corridor with some slush/snow accumulation during the
periods of heavier snowfall.
.LONG TERM...(Friday night through Thursday)
Issued at 321 PM MDT Thu Mar 21 2019
Tomorrow evening will see areas of rain showers and thunderstorms
moving over the plains as a negatively tilted trough continues
on its path toward western Kansas. By Friday morning the closed
upper low will be over western Kansas with northerly flow aloft
over northeast Colorado. Quasi-geostrophic diagnostics shows only
modest dynamic forcing with this trough, so only marginal cooling
of the airmass is expected. Evaporative cooling may be enough for
the tail end of the showers on the plains to begin changing over
to snow, probably after about midnight. In the mountains, evening
snow showers may produce an additional inch or two of snowfall.
Most of Saturday should be dry as weak upper level ridging moves
over the state. Models then show moist zonal flow across state
Sunday with an embedded shortwave trough in the ECMWF model.
Either way, this should bring more snow to the mountains, but keep
the plains dry. Temperatures should be right around seasonal
normals.
The rest of next week shows strong upper level ridging dominating
the weather across the western United States. This will bring dry
and warm weather to the state for the Monday through Wednesday
time period. During the latter half of the week, flow aloft will
become more southwesterly as the upper level ridge axis slides
eastward and over the Central Plains. Moisture aloft should begin
to increase after Wednesday. Afternoon highs on the plains through
much of the week will be in the 60s, if not into the lower 70s on
Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 929 PM MDT Thu Mar 21 2019
VFR conditions will persist through most of this period with only
increasing mid and high level moisture. There is a slight risk of
a passing rain shower after 06Z tonight. Showers and scattered
thunderstorms will develop after 20z and become likely by 00z with
localized MVFR conditions. Wind gusts to 25kts will be possible
at KDEN and KAPA, while KBJC will keep lighter winds.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Sullivan/Gimmestad
SHORT TERM...Barjenbruch
LONG TERM...Dankers
AVIATION...Sullivan/Gimmestad
Area Forecast Discussion
National Weather Service Marquette MI
746 PM EDT Thu Mar 21 2019
.SHORT TERM...(This evening through Friday)
Issued at 416 PM EDT THU MAR 21 2019
WV imagery and RAP analysis indicated a mid/upper level ridge from
the central plains to Alberta and a trough from northeast Canada
into the se CONUS resulting in nnw flow toward the northern Great
Lakes. A shortwave trough was moving into nrn Lake Superior bringing
clouds and some light pcpn into eastern Lake Superior. Otherwise,
breezey west winds under mostly sunny skies has pushed temps into
the mid and upper 40s over most of west and central Upper Michigan.
Tonight, fcst 700-300 mb qvector conv with the shrtwv and
radar/satellite trends suggest suggest that the light rain and snow
showers will move through the area between 21z-00z. QPF toward
Neweberry should remain less than 0.10 inch. Enough cold air with
850/700 mb temps of -12C/-18C and deeper moisture will drop
through Lake Superior to support some light LES for north flow
favored locations. Winds will also become blustery near Lake
Superior with gusts to around 30-35 mph.
Friday, any lingering light LES will diminish during the morning as
dry air quickly moves in with inversion heights dropping at or below
3k ft. Even with mostly sunny skies in the afternoon, temps will
struggle to near 30 north and the lower to mid 30s south.
.LONG TERM...(Friday night through Thursday)
Issued at 310 PM EDT THU MAR 21 2019
High pressure will initially grace the area with its presence at the
start of this forecast period, allowing for benign weather
conditions to prevail tomorrow night into Saturday. As high pressure
drops to the southeast late Saturday, a quick-paced
clipper/associated frontal boundary will march through the U.P. on
Sunday. That said, this doesn`t appear to produce much with little
QPF anticipated overall. Once it completes its passage late Sunday,
look for another round of high pressure to take over on Monday, with
benign weather once again prevailing into the middle of next week.
By Wednesday, deterministic models are generally agreeable on that
being the next chance for precip as a low pressure system tracks
across Northern Ontario.
As for precip types during these two lower-end events, model
soundings and thermal profiles are pointing toward a wintry mix on
Sunday, with rain/snow primarily dominating and perhaps some sleet
mixing in. With temps lingering near the freezing mark in the
northern portions of the U.P., any rain that does fall may freeze on
any remaining sub-freezing surfaces, but with temps as warm as
they`ve been as of late, ice accums will be very limited and likely
unimpactful. And again, QPF amounts are anticipated to be on the
light side, less than a tenth area-wide. Regarding the middle of
next week (Wednesday), temps initially will be supportive of wintry
precip, but should quickly transition over to rain everywhere as
temps rise well above freezing.
Speaking of temps, the chilliest day of the forecast period will be
on Monday with highs topping out in the upper 20s to lower 30s.
Otherwise, temps will remain near or above normal this weekend into
next week, with highs flirting with the 50s for many on Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 745 PM EDT THU MAR 21 2019
As increasingly colder air flows into the area behind a passing cold
front, initial VFR conditions should give way to high MVFR or low
VFR cigs by late evening. Additional low-level moisture and colder
air will also be enough to generate isold/sct light lake effect
-shsn late evening into early Fri morning, mainly at KCMX and KSAW.
Vis restrictions are less likely, but the -shsn may drop vis to MVFR
briefly. Expect clouds to clear out from nw to se during the day
Fri. Winds will be gusty to 20-30kt tonight/Fri, mainly at KCMX/KSAW.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 416 PM EDT THU MAR 21 2019
A few gale force gusts are expected at times late tonight into
Friday morning, mainly over south central Lake Superior. Winds calm
below 25 knots across the lake Friday night and stay there through
the middle of next week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...lg
AVIATION...Rolfson
MARINE...JLB
Area Forecast Discussion
National Weather Service San Francisco Bay Area
847 PM PDT Thu Mar 21 2019
.SYNOPSIS...Dry conditions are expected tonight ahead of the next
frontal system that will bring widespread rainfall to the region
on Friday and Friday night. Mainly dry conditions are expected
over the upcoming weekend, with unsettled weather then likely
throughout at least the first half of next week.
&&
.DISCUSSION...As of 8:45 PM PDT Thursday...Dry conditions
prevailed across our region today, except for an isolated shower
that developed over the Santa Cruz Mountains late this afternoon.
Afternoon highs were mostly in the lower to mid 60s.
Evening satellite imagery shows a relatively robust frontal
system approaching the northern California coast. The moisture
plume along the frontal boundary is respectable with precipitable
water values as high as 1.2 inches. Models agree quite well on
rainfall timing: Light warm advection precipitation is forecast
to begin spreading onto the North Bay Coast just prior to sunrise
Friday, with light rain then developing across the entire North
Bay during the morning hours, and as far south as San Mateo and
Alameda Counties by midday. For tomorrow morning`s commute, wet
roadways are most likely in the North Bay, while locations south
of the Golden Gate will probably remain dry through the bulk of
the morning commute.
Rain rates are expected to increase in the North Bay during the
early afternoon hours as the cold frontal rain band pushes
onshore. Moderate to brief heavy rain rates with the cold front
are then expected to push south and east through the remainder of
the SF Bay Area during the late afternoon and early evening hours,
and finally south through most of the rest of our forecast area
during the late evening hours and overnight Friday night.
Latest HRRR model rainfall totals through late Friday night range
from a half inch to an inch in most locations, except a quarter
inch or less across the far southern portion of our area where the
front is forecast to wash out late Friday night. Up to 1.5 inches
are expected in the North Bay Mountains, Santa Cruz Mountains, and
locally in the Santa Lucia Mountains. The HRRR`s rainfall forecast
with this system is consistent with other model output.
Winds are not expected to be a significant factor with this
incoming system. The local WRF model forecasts locally gusty winds
along the coast from San Mateo County northward, as well as
locally in the hills, on Friday and Friday evening. But wind gusts
in these areas are forecast to be no more than about 30 mph.
The models agree that there won`t be much in the way of post-
frontal shower activity with this system. So, after a few
lingering showers on Saturday morning, mainly across the southern
portion of our area, we can expect dry conditions for the
remainder of the upcoming weekend. Weekend high temperatures are
forecast to be about five degrees cooler than seasonal averages on
Saturday, but then warm a few degrees on Sunday.
After a brief dry break over the weekend, the models agree that
an active weather pattern will return by early next week, with a
system forecast to spread rain across much of our area from Sunday
night into Monday and another set to bring more rain from late
Tuesday into Wednesday. Details regarding timing and exact
location of heaviest rainfall with these systems next week remains
rather hard to pin down given model differences. One item of
note...Yesterday`s ECMWF indicated the potential for prolonged
rainfall in the North Bay from Sunday night through late Tuesday,
with very little break between the two systems, but today`s ECMWF
forecasts about a 24 hour dry break in between.
&&
.AVIATION...As of 11:00 AM PDT Thursday...A few cumulus clouds
over the higher terrain are not impacting the approach or the
terminals today. VFR expected tonight as mid and high clouds
increase and gradually lower ahead of the next frontal system.
Initially a warm front will bring cigs down to MVFR in the Bay
Area with an initial round of light rain Friday morning. There
may be a short break in the rain between the warm front passage
and the arrival of the cold front but cigs likely remaining MVFR.
Vsbys will lower and light to moderate rain will return in the
afternoon.
Onshore winds will diminish tonight then switch to southeast on
Friday. Winds should really pick up in the afternoon in the Bay
Area with gusts to around 25 kt.
Vicinity of KSFO...VFR through tonight. Mid and high clouds will
move in tonight with cigs gradually lowering overnight. MVFR cigs
after 15Z continuing through the day. Light rain could begin as
early as 10-12Z as the warm front moves through. There may be a
short break in the rain late in the morning but rain will return
after 21Z along with reduced vsbys to 3-5 miles. Onshore winds
to 15 kt diminishing overnight then becoming light southeast
Friday morning. Wind speeds increasing after 21Z with gusts to
25 kt.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR tonight. Increasing clouds Friday
morning with cigs remaining in the VFR category. Rain and lower
cigs late in the afternoon. Winds becoming southeast overnight
with stronger gusts through the Salinas Valley. Gusts to 15 kt at
SNS Friday morning increasing to 25 kt after after around 16Z.
&&
.MARINE...as of 04:29 PM PDT Thursday...Weak transitory ridge over
the area through the remainder of the day will result in light to
locally breezy west to northwest winds. Winds turn southerly and
increase by sunrise Friday as a frontal system moves in. A
moderate west swell will dissipate through the next 24 hours but a
different, longer period west swell has already begun to build
into the waters this afternoon.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm from 9 PM
SCA...Pt Arena to Pt Reyes 0-10 nm from 3 AM
SCA...Pt Reyes to Pigeon Pt 0-10 nm from 3 AM
&&
$$
PUBLIC FORECAST: Dykema
AVIATION: W Pi
MARINE: DRP
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