Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/29/18
Area Forecast Discussion
National Weather Service Albany NY
1041 PM EDT Sat Apr 28 2018
.SYNOPSIS...
An approaching cold front will bring some showers and
thunderstorms to the region through this evening, with locally gusty
winds possible. Behind this frontal boundary, colder air will work
back into the area for the rest of the weekend, with some additional
lingering rain and mountain snow showers for Sunday into Sunday
night. Although the week will start off cool with a few additional
showers on Monday, much milder conditions are expected through the
remainder of the week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Updated at 1030 PM EDT... The cold front has now moved east of
the entire forecast area with winds shifting to northwest as
far east the Connecticut River Valley. The steadiest band of
rain continues behind the front over the Berkshires down through
the Taconics east of the mid-Hudson valley, however there has
been a sharp eastern edge with little to no rain getting to
eastern Litchield county so far. We expect gradual eastward
progress with the eastern edge of this rain area overnight,
meanwhile another wave of showers is expected to move north from
eastern Pa across eastern NY late tonight bringing another
round of rain toward daybreak to the mid and upper Hudson River
Valley. Temperatures will slowly fall into and through the 40s,
with some 30s over higher terrain west of the Hudson Valley by
daybreak.
Updated at 830 PM EDT... Cold front is moving slowly east and
has moved east of the mid and upper Hudson Valley as of 830 pm.
A band of moderate rain has developed along and behind the
front. Convection along the leading edge of the this afternoon
has diminished with the loss of heating and modest instability
that was in place earlier today. Strong upper low will move east
across upstate NY overnight. The front will slow down over New
England later tonight with bands of showers continuing to move
north along and behind the slowing frontal zone. Details from
the latest HRRR and 18z NAM nest show that the rain may diminish
for awhile from late evening into the early morning hours from
the Hudson Valley west, however showers will increase across
that area after about 2 am as another wave of rain moves north
along and behind the front. Meanwhile east of the Hudson Valley
rain will continue for much of the night. Temperatures will be
falling behind the front wih most areas settling into the upper
30s to mid 40s by daybreak Sunday.
As of 408 PM EDT...Slow moving surface cold front is moving
across central New York and heading towards the area. MRMS
imagery shows several broken bands of showers and embedded
thunderstorms expanding into eastern New York. Some
showers/storms have already produced pea sized hail and brief
downpours across the area. A more concentrated line of
thunderstorms is located south of the region over eastern PA.
Ahead of the front, diurnal heating has allowed temps to reach
into the 60s over much of the area, although dewpoints remain in
the 40s. 3km HRRR and NAM suggest showers and embedded
thunderstorms will continue to expand eastward across the rest
of the area into the evening hours.
Instability values are fairly meager this afternoon due to low
EL around 500 mb and fairly dry surface dew points. 12z HREF
mean values of surface and MU CAPE values are around 250-500
J/kg for much of the area through this evening and SPC
mesoanalysis is showing similar values so far this afternoon.
However, low and mid level lapse rates are fairly steep and 0-3
KM bulk shear values are around 40 kts, so totally cannot rule
out some gusty winds within any shower or thunderstorm,
especially considering the inverted-v sounding in place. SPC has
placed parts of the Catskills in a marginal risk for severe
weather, mainly due to this threat of locally gusty winds, which
makes sense considering the latest 3km HRRR/NAM reflectivity
output and the heavier line of showers/storms just to our south.
The threat for thunder should wane quickly after sunset, as
instability lowers with the loss of heating.
Behind the cold front this evening, some additional showers will
linger into the overnight hours, especially for northern and
high terrain areas, as low pressure slowly tracks through the
St. Lawrence Valley and the large closed off upper level low
approaches from the Great Lakes. Temps should start to fall out
behind the front, and by late tonight, some wet snow may even
start to mix in with the rain showers across the western
Adirondacks. Lows look to fall into the mid 30s to mid 40s
across the area.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
The large closed off upper level low will track across upstate
New York on Sunday and linger across New England for Sunday
night into Monday. With the cyclonic flow in place, some
additional showers look to occur for Sunday into Monday,
especially for northern and high terrain areas. Best timing for
most concentrated areas of showers looks to be Sunday afternoon
through late Sunday evening, and then again of the backside of
the upper level low for Monday morning.
With the core of the upper level low over the area, 850 hpa
temps will fall to -2 to -5 C. For most of the area, the
boundary layer will be too warm for any snowfall, but high
terrain areas may see some wet snow mixing in and parts of
western Adirondacks and southern Greens may even see a light
accumulation across the highest elevations.
High Temps on Sunday look to generally be in the 40s to low 50s
across the area, although some upper 30s will occur across the
Adirondacks. Lows on Sunday night look to fall into the 30s
everywhere. Highs on Monday will be in the mid 40s to mid 50s.
As the upper level low starts moving away, the threat for
showers should be diminishing by Monday night and it will
finally start to clear out. Lows will be in the 30s once again.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
A progression of dry to showery weather is in store...with
temperatures averaging above normal. High pressure sliding off
the southeast coast on Tuesday will bring increasing moisture
and clouds into our area as the week progresses. Things will
start out dry...becoming downright warm by mid-week. Only
showers moving into the area on Thursday will serve to cool the
lower atmosphere in any way before the passage of a cold front
from the northwest at the end of the week. A rumble of thunder
is not out of the picture on Thursday, but instability is
expected to be limited.
High temperatures will be in the upper 50s to lower 70s range on
Tuesday, the upper 60s to lower 80s on Wednesday. Thursday will be
similar to Wednesday, with slightly cooler temperatures noted for
Friday. Saturday will be a very pleasant and generally dry day,
with highs from around 50 degrees in the Adirondack high peaks...to
near 70 in the lower Mid-Hudson Valley. Normal early May highs in
Albany are in the mid 60s, with the normal lows in the mid 40s.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Cold front has moved east of the Hudson Valley as of 730 pm and
will be east of PSF by around 900 pm. Showers will continue
along and behind the front through tonight and lingering into
the day on Sunday. Conditions will be mainly VFR through this
evening but there will be periods of MVFR cigs and vsbys in
showers. Cigs will lower to mostly MVFR later tonight through
Sunday morning, then improve slightly with areas of VFR by
Sunday afternoon.
Winds will be west- northwest, with some brief higher gusts at
POU and PSF this evening with the frontal passage, otherwise
west-northwest winds can be expected tonight through Sunday with
speeds averaging less than 10 kts.
Sunday Night: Moderate Operational Impact. Chance of SHRA.
Monday: Moderate Operational Impact. Chance of SHRA.
Monday Night: Low Operational Impact. Slight Chance of SHRA.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
&&
.FIRE WEATHER...
A cold front will pass through this evening with some showers
and thunderstorms. With an upper level disturbance over the
area, some additional rain and mountain snow showers will occur
for tonight through Monday. Most areas look to see a wetting
rainfall from this precipitation.
Through the remainder of the weekend and into Monday, RH values
will stay elevated, generally above 50 percent. West winds
tomorrow will be 10 to 20 mph and remaining west for Monday at 5
to 10 mph.
&&
.HYDROLOGY...
Some showers and thunderstorms are expected through this evening
with the passage of a cold front. Behind the front, some
additional showers are expected to linger for Sunday into
Monday, thanks to a large upper level disturbance moving over
the area. The precip may changeover to snow showers for the
highest terrain late in the weekend, but liquid equivalent
amounts are expected to range from a quarter of an inch over far
southern areas to nearly an inch over the Adirondacks.
This precipitation will allow for some additional rises on
rivers and streams but river levels are expected to remain below
flood stage. A few rivers and reservoir levels in the
Adirondacks where flows have been high due to recent rainfall
and snowmelt may hover near action stage, but latest forecasts
don`t anticipate flooding at this time.
Dry weather is then expected for Tuesday into Wednesday with
mild weather. River levels should continue to recede. Most of
the hydrologic significant snowfall has already melted out of
the Adirondacks, but any remaining snowpack should melt this
week.
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...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Frugis
NEAR TERM...MSE/Frugis
SHORT TERM...Frugis
LONG TERM...ELH
AVIATION...MSE/Speciale
FIRE WEATHER...Frugis
HYDROLOGY...Frugis
Area Forecast Discussion
National Weather Service Binghamton NY
953 PM EDT Sat Apr 28 2018
.SYNOPSIS...
A cold trough of low pressure will provide unsettled
conditions and chilly temperatures through the rest of the
weekend and into Monday. Drier weather, with a significant
warming trend, is anticipated next week.
&&
.NEAR TERM /THROUGH SUNDAY/...
Behind a cold front, northwest and northerly flow will result
in snow showers developing overnight and likely continuing
through Sunday and into Sunday night. Gusty winds expected on
Sunday with temperatures in the 30s and lower 40s. Few changes
were made with the late evening update overnight incorporating
aspects of the latest mesoscale model guidance.
A cold front has moved through our region this evening. Behind
the front, Winds will shift to the nw and colder air will
spread across the region. The broad large scale lift from the
upper low will combine with CAA in the mid levels with
steepening lapse rates, and allow the showers to persist
tonight...but mainly keep most of the precip confined to central
NY...with even a small amt of support from Lake Ontario
possible. 850mb temperatures will drop into the -4 to -6 deg C
range tonight, and allow the development of snow showers or a
mix of rain and snow. Snow will likely have a hard time
accumulating...but the higher elevations above 1500 ft may see a
half to 1 inch of snow by mid Sunday morning.
The cold air continues to filter in during the day Sunday with
gusty nw winds making it feel even colder. Highs during the day
will likely have a hard time getting much above 40. The cold air
aloft and slightly unstable air mass is expected to continue to
be supportive of snow showers or a mix of rain and snow through
most of the day...but with much of the snow not accumulating
during the daylight hours. We are starting to get into the range
of the HRRR and RAP now. These models late this evening are
indicating the showers to be fairly widespread so the pops were
increased for most of the day Sunday.
The low pressure system will track slowly ewd Sunday and remain
an influence over much of the region into Sunday night. There is
a gradual warming trend, but likely not warm enough during the
overnight hours to change the snow to rain. So, will likely see
scattered snow showers continue through the night with an
additional half to 1 inch in the higher terrain once again. The
area that has the best chance of seeing accumulating will be
across the highs south of Syracuse and into the Catskills and
srn Tug Hill.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
220 PM update...
Significant changes will occur this period, beginning with an
abnormally cold trough sliding out of NY to give way to a warm
trough building into the Ohio Valley and Great Lakes.
A mix of rain and snow showers is forecast for early Monday. A
few tenths of snow accumulation are expected over high
elevations, before temperatures warm into the lower or middle-
50s during the afternoon.
The ridge axis will cross Lake Erie on Tuesday. The GFS is
forecasting a wave to rotate over the top of the ridge and
cause a few showers over NY. We are sticking to a dry forecast
at this point, as the other models disagree with the GFS
assessment.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A mild, spring-like pattern is forecast for the long term
period. The ridge will flatten on Wednesday, while a weak
cyclone will move across Southern Ontario Province. This system
may set off a shower or thunderstorm Wednesday afternoon.
Additional shower activity is possible on Thursday as a complex
frontal system moves east toward the Great Lakes. A cyclone will
form along the front over Michigan and track toward NY Thursday
night, increasing the likelihood for rain.
The storm system will pull a cold front across NY and PA on
Friday.
Temperatures will reach well into the 70s on Wednesday and
Thursday, then drop several degrees behind the cold front
Friday.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
A cool moist northwest flow will continue over the area through
this TAF period with lowering ceilings early this evening. At
KRME/KSYR/KITH/KBGM, ceilings will lower into the Alternate
Required category shortly then to IFR between 04Z-06Z. At
KELM/KAVP, ceilings will lower into the MVFR/Alternate Required
category between 03Z-06Z. Conditions may slowly improve Sunday
by 15Z to Alternate Required/MVFR conditions along with MVFR
visibility restrictions in mixed rain/snow showers especially at
KRME/KSYR/KITH.
Northwest winds at 8-10 knots overnight increasing mid morning
Sunday at 12 knots with gusts 18-22 knots.
Outlook...
Sunday night...MVFR/IFR restrictions possible from rain
showers, and at times, snow showers.
Monday through Wednesday...VFR.
Thursday...Restrictions possible in showers and isolated thunderstorms.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...BJT
NEAR TERM...BJT/MWG
SHORT TERM...DJP
LONG TERM...DJP
AVIATION...RRM
Area Forecast Discussion
National Weather Service Bismarck ND
903 PM CDT Sat Apr 28 2018
.UPDATE...
Issued at 900 PM CDT Sat Apr 28 2018
Red Flag Warning expires at 9 PM CDT as critical fire weather
conditions have subsided. Also the wind advisory has also
expired. While gusty winds will continue for a bit the strongest
winds have abated.
UPDATE Issued at 625 PM CDT Sat Apr 28 2018
Strongest surface winds following the h850 wind profile with
HRRR soundings showing a decoupling around 02z/9 pm cdt. Winds
will decrease a bit then but remain gusty through the evening.
Current forecast looks ok. Wind advisory southwest and Red Flag
Warnings continue through 9 pm cdt.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 240 PM CDT Sat Apr 28 2018
Winds and critical fire weather conditions continue to highlight
the short term period.
Currently, upper level ridge axis stretches from south to north
across the high plains east of the Rockies. Surface high pressure
over the Upper Mississippi Valley and low pressure developing over
the Northern Rockies has developed a tight pressure gradient
across western and central North Dakota today. Gusty
south/southeasterly winds developed in response over much of my
area. Coupled with a dry boundary layer and lack of moisture
advection, resultant mixing from these winds has seen decreasing
humidity as the day progresses. Already reaching Red Flag criteria
and this will only get worse as the afternoon progresses and more
locations dry out. Lack of a good green-up/dry 1-hr fuels only
exacerbating critical fire weather conditions today.
Will see improving fire weather conditions early to mid evening as
we decouple and the mixed layer lowers, resulting in winds
decreasing. Will also have cooling temperatures seeing RH values
increase.
Breezy south/southeast winds re-increase a bit overnight as a
very strong low level jet (LLJ) develops (40-55Kts) into the
Northern Plains. Main impacts from the LLJ will be an increase in
low level wind shear impacting aviation as the boundary layer
remains parched until after 12Z Sunday. Upper ridge axis moves
into the eastern Dakotas by sunrise Sunday morning.
Surface trough moves into the western Dakotas Sunday afternoon as
southwest flow aloft develops from the Rockies into the Plains.
Increasing boundary layer moisture through the day with sfc
dewpoint temperatures increasing well into the 40s to near 50F.
Daytime highs still expected to range well into the 70s as 900MB
temps increase from 7-12C today to 17-23C Sunday aft. All guidance
keeps my area dry until Sunday night when the better large scale
forcing arrives from the west as the upper level low moves into
the Northern Rockies region.
.LONG TERM...(Sunday night through Saturday)
Issued at 240 PM CDT Sat Apr 28 2018
Thunderstorm potential Sunday night and perhaps Monday, and an
early May cool down, highlight the extended forecast.
See the fire weather discussion below for details regarding
possible fire weather concerns for Sunday.
SPC has maintained a marginal risk for severe thunderstorms across
southwest North Dakota Sunday evening. The 12Z models continue to
suggest convection initiating across southeast Montana and
northern Wyoming, then propagating northeast into southwest North
Dakota Sunday evening. This convection is expected to be
sustained by steep mid level lapse rates and a strong mid level
jet ahead of the upper low. Convection may be consolidated, and
elevated, by the time it reaches North Dakota. Wind would seem to
be the primary threat given the dry air with sfc Tds barely
touching 50F. However, this could be limited by stabilization of
the boundary layer. Marginal severe hail is also possible, but, a
likely secondary threat. The thunderstorm threat will propagate
into central North Dakota overnight. However, the severity is
somewhat uncertain but should decrease with time.
For Monday, thunderstorm potential and severity looks to reside
more to our south and southeast. Have tempered thunder mention due
to the latest guidance.
Thereafter, models still suggest on average cooler/below normal
temperatures for the start of May, highs in the upper 50s and
lower 60s and lows dropping into the 30s, as the mean flow will be
northwest. Possible ridging late next week may see the one or two
days closer to average temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 625 PM CDT Sat Apr 28 2018
Strongest surface winds following the h850 wind profile with
surface wind gusting to 30-35kts KDIK-KBIS til 02Z. Then forecast
soundings show a decoupling around 02z resulting in a lower
surface winds but a low level speed max over 50 kts around 1
thousand feet agl over west central North Dakota. VFR at all taf
sites with wind shear to 50 KTS below 1 thousand agl KJMS- KBIS-
KMOT- KDIK.
&&
.FIRE WEATHER...
Issued at 240 PM CDT Sat Apr 28 2018
Red Flag Warning remains in effect through early this evening for
western and most of central North Dakota.
Strong southeast winds have developed across the area today and
will continue before winding down this evening. Peak gusts have
ranged from 30 - 40 mph with sustained winds ranging from 20-25
for the most part. Relative humidity continues to fall, now in the
low 20s to mid 30s, and will bottom out to near 20 percent if not
a tad lower some locations in the mid/upper teens. Expect
improving conditions between 7-9PM CDT this evening.
For Sunday: gusty south/southeast winds will continue over south
central and eastern parts of North Dakota. Sustained winds to 25
mph and gusts to 35-40 mph are forecast for these areas. However,
increasing surface moisture tonight into tomorrow will see higher
relative humidity values on Sunday, ranging from 30-40 percent.
This will limit the fire weather threat but will be closely
monitored.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WAA
SHORT TERM...NH
LONG TERM...NH
AVIATION...WAA
FIRE WEATHER...NH
Area Forecast Discussion
National Weather Service Wichita KS
1012 PM CDT Sat Apr 28 2018
.UPDATE...
Issued at 1011 PM CDT Sat Apr 28 2018
Low level jet just beginning to slowly increase for areas west of
I-135 at this time, with a gradual increase in low level moisture
transport. Latest RAP model data suggests that moisture transport
will be slow to increase into central KS overnight, with a general
increase for areas over north central KS. So think any chance of
showers or an isolated storm will be delayed. Rap shows moisture
transport possibly increasing enough for a rogue storm or two north
of I-70 across north central KS, after 09z, but confidence in this
occurring is diminishing. Will keep a slight pop in for now, but
think precip chances into early Sun morning look slim.
Ketcham
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 253 PM CDT Sat Apr 28 2018
Water vapor imagery shows the upper low coming on shore over the
Pacific NW with upper ridging about to move out of the Rockies and
into the high Plains. At the surface, a cold front extends from
northern AR into far sw KS.
Models have remained consistent the last several days in lifting a
piece of energy out of the Desert Southwest and into the central
Plains late tonight into Sun morning. As this occurs, decent mid
level theta-e advection sets up along and northeast of a tight mid
level baroclinic zone. While it`s not out of the question to see
some iso thunder with this activity over central KS, not expecting
anything strong or severe. Return flow will start to get going on
Sun as lee troughing continues to deepen with south winds
expected to be even stronger on Mon. Will run with a wind advisory
Sun afternoon for a few central KS counties with another wind
advisory eventually needed Mon for a much larger area.
One upper impulse will be lifting over western Nebraska on Mon
night while a much more robust piece of energy will be approaching
the southern CA coast. Strong return flow will keep strong
moisture advection in place across the Plains and by Tue
afternoon, a dryline will extend from west-central KS down into
western OK. Meanwhile, a cold front will extend through eastern
Nebraska into central KS. With lack of large scale forcing, will
likely take an area of enhanced convergence along of the
boundaries to get a storm to develop late Tue afternoon/Tue
evening. At this time, feel the best surface convergence will be
near the triple point over central KS. So while not expecting
widespread severe storms Tue, can`t rule out a few storms. Will be
plenty of instability and shear to get supercells along both the
dryline and synoptic front.
.LONG TERM...(Wednesday through Saturday)
Issued at 253 PM CDT Sat Apr 28 2018
Stronger mid/upper flow will move out across the southern/central
Plains for Wed as the main upper impulse slides over the Desert
Southwest. Meanwhile, low level moisture will continue to pump
into the region with mid 60 dewpoints a good bet by Wed afternoon.
Once again, expecting a triple point to be located somewhere over
west-central KS by Wed afternoon with the dryline extending
into western OK. Currently expecting more widespread storms along
the dryline/warm front Wed due to less capping, better large scale
forcing and richer low level moisture. 0-6km shear will be in the
50 to 60kt range with CAPE in the 2500-3000J/kg range. Low level
shear isn`t that impressive until surface flow starts to back
closer to sunset as low level jet increases. Deep layer shear
looks to be normal to the dryline which should keep anything that
develops along it fairly isolated which should minimize storm
interaction and increase tornado potential, especially toward
evening.
Also seems to be some model agreement now that much of eastern KS
will be in play for severe storms Thu afternoon and evening as
the front appears slower to push east. Of course, much of that
will be dictated by how Wed evening storms modify the environment,
but think it`s at least worth a mention at this point. So we
could be looking at a 3 day severe weather event across the
Plains.
Cold front will push well south of the area for Fri and Sat as
high pressure settles over the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 642 PM CDT Sat Apr 28 2018
VFR conditions are expected for the next 24 hours. HI-rez short
range models suggests that there is a chance for some elevated
SHRA/VCTS to develop across central KS early on Sun morning, during
the 09-12z/Sun time frame. Will keep a VCTS going for this chance
for the KRSL and KSLN taf sites. Could also see some low level wind
shear for the central KS tafs overnight, as the low level jet
increases.
Ketcham
&&
.FIRE WEATHER...
Issued at 253 PM CDT Sat Apr 28 2018
Fire danger concerns will return to the area Sun and especially
Mon.
South winds will be on the increase for Sun and especially Mon.
For Sun, we are looking at south/southeast winds sustained around
30 mph with gusts to 40 mph for areas generally west of I-135. For
Mon, we should see widespread south winds in the 30-35 mph range
with gusts 40-45 mph. This will elevate the grassland fire danger
into the very high category for areas west of I-135 Sun afternoon
and for most of the area Mon afternoon. Grasses starting to green
up and higher RH values will keep the grassland fire danger from
getting into the extreme category.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 51 77 60 79 / 10 10 0 10
Hutchinson 50 77 60 80 / 10 10 0 10
Newton 49 76 59 78 / 10 20 0 0
ElDorado 49 76 59 78 / 10 10 0 0
Winfield-KWLD 51 77 59 79 / 10 0 0 10
Russell 50 80 61 84 / 30 10 10 10
Great Bend 51 81 60 82 / 20 10 10 10
Salina 50 79 61 83 / 20 30 10 10
McPherson 50 77 60 80 / 20 20 0 10
Coffeyville 48 75 57 79 / 10 0 0 0
Chanute 46 73 56 78 / 10 10 0 0
Iola 45 73 56 78 / 10 10 0 0
Parsons-KPPF 47 75 57 78 / 10 0 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from noon to 8 PM CDT Sunday for KSZ032-033-047-
048-050.
&&
$$
UPDATE...Ketcham
SHORT TERM...RBL
LONG TERM...RBL
AVIATION...Ketcham
FIRE WEATHER...RBL
Area Forecast Discussion
National Weather Service San Francisco Bay Area
850 PM PDT Sat Apr 28 2018
.SYNOPSIS...Isolated light showers or sprinkles are possible
through about midday Sunday, mainly in the North Bay. Otherwise,
expect dry and continued cooler than normal weather through
the middle of next week. High pressure will start to build
midweek and beyond with a modest warming trend expected during
the second half of next week.
&&
.DISCUSSION...As of 8:50 PM PDT Saturday...An upper low moving
inland over the Pacific Northwest and far northern California
produced isolated light showers and sprinkles in the Bay Area
today. Most locations only received a trace of precipitation, but
a few locations managed to pick up a hundredth or two.
Temperatures today remained slightly below normal in most
locations.
The 00Z NAM shows isolated light showers redeveloping in our area
later tonight and into Sunday morning as the upper low begins to
dig to the southeast and as a shortwave trough rotates to the
southwest of the low and across our area. The latest HRRR model
also indicates spotty light precipitation, mainly in Sonoma
County. A forecast update was completed earlier this evening to
add a slight chance of showers to the forecast for late tonight
and Sunday morning, mainly in the North Bay, but also south along
the SF Peninsula. If showers do develop in these areas,
accumulation is expected to be very light and similar to what
occurred today.
Another upper low is forecast to drop in from the north late on
Monday. Initially, from late Monday through most of Tuesday, the
models agree that precipitation with this low will mostly be
confined to our east over the Sierra Nevada. But then, as the low
sinks to our southeast late Tuesday, both the 00Z NAM and 18Z GFS
show a disturbance rotating to the northwest of the low and
triggering showers across the southeastern portion of our area
from late Tuesday into Tuesday night. Our forecast currently does
not include shower chances then, but chances will likely be added
to the forecast if the 00Z GFS and/or 00Z ECMWF show something
similar to the 00Z NAM.
These upper lows will maintain cooler than normal temperatures
across our area through the middle of next week. Longer range
models forecast an upper ridge to build across California during
the second half of next week, resulting in dry and warmer weather.
&&
.AVIATION...As of 4:50 PM PDT Saturday...Upper level low has
brought SCT-BKN cloud decks to the SFO Bay Area and North Bay.
A few showers were reported earlier but have moved out. More cigs
have developed this afternoon but bases are high enough to
maintain VFR conditions. The inversion will reform at a lower
level after 05Z with areas of MVFR.
Vicinity of KSFO...VFR with cigs at or above 3500 feet through
05Z. Lower deck of clouds form after 05Z with conditions becoming
MVFR.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...Onshore flow will allow for MVFR cigs
after 03Z in MRY slowly spreading to SNS by 09Z.
&&
.MARINE...as of 5:20 PM PDT Saturday...Northwest winds will
gradually increase over the next 24 hours throughout the coastal
waters as a system drops from the Pacific Northwest. Moderate
winds are forecast to continue into the early part of next week.
These winds will produce fresh swell and steep waves.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
&&
$$
PUBLIC FORECAST: Dykema
AVIATION: W Pi
MARINE: W Pi
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Area Forecast Discussion
National Weather Service Spokane WA
456 PM PDT Sat Apr 28 2018
.SYNOPSIS...
Sunday through Tuesday will feature seasonal temperatures with
occasional showers. The cool and unsettled weather will ease by
midweek as a ridge rebuilds over the Inland Northwest with warmer
and drier weather.
&&
.DISCUSSION...
Tonight through Monday: An upper-level low will slowly migrate through
the region during this period. Smaller scale disturbances
rotating around the low will delivering periods of showers with
most activity tracking over the periphery of the Columbia Basin.
Away from this features, afternoon heating will bring a threat for
hit or miss light showers. There will be a small chance for
thunderstorms across far southeastern WA and the lower ID
Panhandle each of the next few afternoons/early evenings and into
NE WA Sunday afternoon but instability parameters are marginal so
not expecting much more than infrequent lightning strikes. HRRR is
also indicating a few cell developing around the Waterville
Plateau this evening so this is something that will be monitored
through sunset. Precipitation amounts over the next few days will
generally be light except on a highly localized basis under any
convective cells. In general, less than a quarter of an inch is
expected over the next 48 hours. Temperatures will remain on the
cool, seasonal side with afternoon highs in the 50s to 60s and
lows in the upper 30s to 40s. Rainfall from the last 24 hours will
keep a small chance for patchy fog in the morning hours in and
around the sheltered northern valleys. /sb
Monday night through Tuesday night...By Monday night the upper
low will be well away from the Pacific Northwest. Northwest-
northerly flow and lingering moisture will keep a chance of rain
showers and high elevation snow showers across the eastern third
of the forecast area, east of a line from Republic to Ritzville.
Precipitation amounts will be under a tenth of an inch in the
north Panhandle and a few hundredths elsewhere. Temperatures will
begin to warn through this period with high temperatures from the
high 50s to around 70.
Wednesday and Thursday...High pressure will build into the region
for a warming and drying trend. Temperatures will warm 4-6
degrees on Wednesday and another 3-4 degrees Thursdays which will
put the highs in the 60s to 70s.
Friday and Saturday...Model guidance has been consistent showing
the ridge flattening out Friday and Saturday with another weather
system coming through the region on Sunday. The ECMWF on the other
hand is about 24 hours quicker with the low. For now the forecast
will lean in favor of the slower solution with the ridge flatting
and the low pressure system coming in on Sunday. That will mean
cooler temperatures, and an increasing chance for showers across
the northern mountains on Friday and and just about all areas on
Saturday. Tobin
&&
.AVIATION...
00Z TAFS: Afternoon heating will keep the chance of showers for
KCOE through sunset, while shower chances linger through 08 or 09Z
for KLWX and KEAT. VFR conditions are expected at all TAF sites.
There will be a chance for some early stratus at KGEG-KCOE given
the wind direction and cool, moist boundary layer. Some weak
disturbances will bring the chance for scattered afternoon showers
again on Sunday for KPUW, KLWS, KCOE, and potentiall KGEG and
KSFF. /bw
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 41 59 41 58 41 60 / 10 10 10 30 10 20
Coeur d`Alene 42 58 39 57 39 58 / 10 10 20 40 20 20
Pullman 41 56 39 55 39 57 / 40 20 10 20 10 20
Lewiston 46 62 44 61 43 63 / 50 20 20 20 10 20
Colville 43 59 41 63 41 67 / 20 40 30 30 10 20
Sandpoint 41 57 38 55 39 56 / 30 20 40 40 20 30
Kellogg 39 56 37 53 37 54 / 20 30 20 40 30 40
Moses Lake 42 66 42 66 41 68 / 10 0 10 10 10 10
Wenatchee 44 62 43 64 42 67 / 10 10 10 10 10 10
Omak 44 61 42 65 42 67 / 20 10 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Mount Holly NJ
945 PM EDT Sat Apr 28 2018
.SYNOPSIS...
A strong cold front will pass through our region this evening.
Low pressure is forecast to meander in New England and vicinity
on Sunday and Monday as high pressure slides from the Great
Lakes to the Carolinas. The high is expected to settle over the
western North Atlantic and it should influence our weather from
Tuesday into Friday. Another cold front approaching from the
northwest is forecast to arrive on Friday night.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
930 pm update: Extended isolated thunder chances in the forecast
for the next few hours given the continued flare-up of isolated
storms near/southeast of I-95 and in portions of Delmarva.
Cells continue to exhibit pulsing nature with small hail still
possible (though quite isolated) where towers reach around/above
20 kft. Light rain is picking up to the west, so gradually
increasing PoPs north of the Mason-Dixon Line for much of the
night continues to make sense.
800 pm update: Line of low-topped showers and isolated storms is
beginning to wane as nocturnal cooling commences. However, the
storms were rather prolific producers of small hail, as
virtually any storm with discernible radar echo tops to 20,000
feet was able to produce hail that reached the surface. Several
reports of pea-sized hail (or even slightly larger) were
received with a storm near Coatesville, PA, and with a line of
storms affecting Sussex, Warren, Hunterdon, and Morris Counties
between 5 pm and 7 pm.
Have had to make several changes to the forecast to account for
the evolution of the precipitation this evening and will likely
make a couple more in the next couple of hours. Main change was
to boost PoPs rather substantially tonight based on NAM Nest and
HRRR continuing to indicate showers developing and moving
through much of eastern PA and northern/central NJ. This is
already bearing out to some degree, as showers continue to
develop in Berks/Chester Counties southward into
northern/northeast MD and westward into south-central PA.
Hourly temperatures will be rather chaotic this evening as
rain-cooled air will generate rapid changes to temperatures. The
overall trend during the night is a little warmer/moister, so
raised hourly temps/dews a couple degrees beyond 10 pm.
Previous discussion...
Elongated area of low pressure currently situated along a cold
front over central PA extending north into upstate NY with a
line of showers along this front moving east. Meanwhile, across
the forecast area, we are in the warm sector with a southerly
flow allowing temps to get well into the 60s with even some 70+
degree readings. As we go through the latter part of afternoon,
the aformentioned cold front and line of showers will be moving
east and should enter our western counties beginning by around
21z. Instability will be increasing as this occurs with high res
models suggesting a few hundred J/kg of ML CAPE by the time the
line moves in. Low level lapse rates will also be fairly steep
with a fairly strong flow through the boundary layer and deep
layer shear near 50 knots. For this reason, expect line to
intensify with isolated thunder still possible. Also, showers
and any storms could produce gusty winds and it`s worth noting
that the Storm Prediction Center has placed most of eastern PA
into NW NJ into a marginal risk for severe storms. This means a
few locally severe storms could occur though we are not
expecting this to be a significant widespread severe weather
event. Damaging winds are the biggest threat.
By around 8 pm this evening, showers should be reaching the
I-95 corridor but instability will be decreasing by this time
with any risk of thunder and severe weather quickly diminishing.
Beyond this time, showers will continue pushing east through NJ
as the front moves east with some indications some additional
showers could re- develop just behind the front back toward the
I-95 corridor by the later evening so we keep at least chance
POPs in the forecast through this period. Precip should finally
move out overnight as the front pushes off the coast and low
pressure re-organizes over New England. Brisk NW winds will also
be setting up by this time due to the strengthening pressure
gradient between this low and high pressure over the midwest.
Lows by morning will generally be in the upper 30s to mid 40s
except mid 30s over the southern Poconos.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
For Sunday, upper level trough supporting the surface low
described above will be closing off into a closed upper low over
the northeast. This combined with the continuing brisk NW winds
will result in a much cooler day with considerable cloud cover,
especially north. Also, some scattered to isolated showers will
be possible across the far north through the southern Poconos
and it`s possible these could even be mixed with a little snow
as highs here will only be in the low to mid 40s. Elsewhere,
expect highs generally in the 50s. However NW winds 10-20 mph
will make it feel cooler.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
The mid level pattern on Sunday night will feature troughs over
the northeastern and northwestern states with a ridge up the
middle of the country. The trough over the northwest is forecast
to deepen as the ridge and the northeastern trough progress to
the east. The axis of the ridge is expected to pass over our
region on Tuesday night. Temperatures will start the work week
below normal. However, the pattern change will result in well
above normal temperatures late in the week.
Surface low pressure will continue to lose its influence over
our weather gradually during the period from Sunday night
through Monday night. We are anticipating a good deal of cloud
cover on Sunday night and Monday from the Poconos and the Lehigh
Valley into northern and central New Jersey. We have included
the mention of a low or slight chance of rain showers in those
areas. Actually, we may end up seeing a fair amount of virga on
Monday afternoon up there as the lower levels continue to dry. A
partly cloudy sky is anticipated for northeastern Maryland,
Delaware and southern New Jersey. The sky is forecast to become
mostly clear for Monday night and Tuesday and temperatures
should begin their rise to above normal levels.
Surface high pressure is expected to become established over
the western North Atlantic resulting in a south to southwest
surface flow in our region from Tuesday into Friday. Warm and
mostly rain- free weather is anticipated.
Weak disturbances traveling over the ridge in the mid level
flow may bring some showers and thunderstorms to areas to our
northwest and north from late Wednesday into early Friday. The
potential for any precipitation making its way into our
northwestern counties appears slim but we have included the
mention of a slight chance of precipitation there.
Our best chance for showers and thunderstorms in the long-term
period of the forecast is from Friday afternoon into Friday
evening, ahead of a cold front approaching from the northwest.
It appears as though the front will pass through our region on
Friday night, with clearing anticipated for Saturday.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...Generally VFR with CIGs 4000-7000 feet, though brief
MVFR CIGs/VSBYs may occur with showers. Showers may continue at
most TAF sites off and on through the early morning hours, but
should be done by sunrise (with possibly some scattering of the
CIGs by this point). Winds becoming west-northwest 10 to 20
kts, potentially with gusts near any showers. Moderate
confidence.
Sunday...VFR with SCT-BKN CIGs near 5000 feet, especially
during the late morning and afternoon. West-northwest winds 10
to 20 kts with gusts to 30 kts. Moderate confidence.
Outlook...
Sunday night through Thursday...Mainly VFR.
&&
.MARINE...
Made a lot of changes to the forecast and the current small
craft advisory. With conditions nearing criteria already on
Delaware Bay, bumped up the start time to 1 am for the bay and
adjacent Atlantic waters. Meanwhile, delayed start time of the
northern/central New Jersey coastal waters until tomorrow
evening, when lapse rates may prove more favorable for mixing
down the stronger west/northwest winds. Finally, extended the
advisory for all locations through Sunday night based on the
latest forecast guidance.
Isolated showers/storms may occur tonight on the waters, with
gusty/erratic winds and locally higher waves where these showers
occur. The threat should diminish by Sunday morning.
Outlook...
Monday through Thursday...No marine headlines are anticipated.
&&
.FIRE WEATHER...
A northwest wind of 15 to 20 mph with gusts around 25 mph is
anticipated for Monday afternoon. Relative humidity values are
expected to drop into the 20s in much of southeastern
Pennsylvania, southern New Jersey, Delaware and northeastern
Maryland. If the forecast does not change, we will coordinate
with our fire weather partners on Sunday to see if any special
fire weather products should be issued for Monday.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 6 PM Sunday to 6 AM EDT Monday for
ANZ450>452.
Small Craft Advisory from 8 AM Sunday to 6 AM EDT Monday for
ANZ453.
Small Craft Advisory from 1 AM Sunday to 6 AM EDT Monday for
ANZ430-431-454-455.
&&
$$
Synopsis...Iovino
Near Term...CMS/Fitzsimmons
Short Term...Fitzsimmons
Long Term...Iovino
Aviation...CMS/Iovino
Marine...CMS/Iovino
Fire Weather...Iovino