Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/26/17
Area Forecast Discussion
National Weather Service Binghamton NY
841 PM EDT Tue Apr 25 2017
.SYNOPSIS...
A storm center along the eastern seaboard, will bring a period
of rain to most of the area tonight, before weakening and
moving farther out to sea. Wednesday and Thursday look generally
rain free and warm, with afternoon highs near 70 Wednesday, and
in the seventies to near 80 Thursday. Our next chance of
showers or thunderstorms, will come Thursday night into Friday,
associated with a weak frontal system.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
830 pm update...Weak nads of showers continue to move through
the forecast area this evening. Meso scale models show showers
continuing...mainly over the east...for the next few
hours...then scattereing out. HRRR does show another batch of
heavier showers moving through late so will continue a chance or
likely in case that does indeed happen. Temperatures are higher
over the Finger Lakes and cooler over the Catskills but will
continue to slowly fall.
330 pm update... The next batch of rain, tied to the closed low
along the mid-Atlantic coast, is coming up through eastern PA
and NJ this afternoon. It should affect areas primarily near
and east of the I-81 corridor this evening. Rain should taper
off later tonight, as the upper low begins to fill and drift
farther out to sea.
Tonight will be fairly mild, with overnight lows ranging from
the upper 40s-mid 50s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
340 pm update... The coastal disturbance mentioned above will
continue to weaken and drift eastward Wendesday. Any lingering
showers in the far eastern zones should be done by 8-9 am, at
the latest.
However, with low-level moisture trapped underneath a subsidence
inversion, clouds will be slow to depart, especially across the
Poconos and Catskills. By afternoon, though, we expect that most
of the region will see at least partly sunny skies.
Given no cool air source behind the coastal low, temperatures
will be quite mild Wednesday afternoon, reaching the upper 60s-
lower 70s. Lows Wednesday night will only drop into the 50s-near
60, as a S-SE warm advective flow begins to increase overnight.
Thursday should be a warm day, with southerly winds in place
ahead of a slowly approaching cold front in the Ohio Valley. A
marine-layer type cloud mass could affect our far eastern zones
in the morning (the Pocono plateau and the Catskills), but these
clouds should start to break up by/during the afternoon.
Afternoon highs should range from near 70 over the higher
terrain of the Catskills, to the lower 80s in some of our Lake
Ontario plain locales.
Thursday night and Friday morning, the above referenced cold
front will advance eastward across CNY/NEPA, but will be
weakening as it does so, with nearly all of the discernible
upper-level energy tracking well north into Canada. An area of
showers, and perhaps a few thunderstorms, entering our western
zones Thursday evening, should have a tendency to diminish with
eastward extent late at night into Friday morning.
Friday afternoon should end up rain-free, with the front moving
off to our east by this time. Given weak thermal advections
behind the boundary, highs should still be solidly in the 70s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
250 PM UPDATE...A difficult weekend forecast is setting up in
the medium range models which hinges upon the positioning of a
West-East oriented frontal boundary. The ECMWF suppresses the
front to our south by Saturday night, while the GFS and Canadian
Global models reside furthest to the north and closer to the
NY/PA State border. This means the difference between a
cooler/drier start to the weekend and a slightly milder, but
wetter one. All of the model solutions appear to limit
precipitation on Saturday night as high pressure across Canada
surges south, then Sunday brings a return of the warm front to
our north with more clouds, showers, and even thunderstorms in
tow. Agreement becomes better early next week that a powerful
cyclone will develop and move through the upper Midwest,
eventually sweeping a strong cold front through our area on
Monday. Tuesday seems to show limited chances for precipitation,
but turning cooler than average.
Due to the higher level of uncertainty associated with this
forecast, there will be varying chances for rain and
thunderstorms all weekend into early next week, although this
may turn out to sound more pessimistic than what reality may
actually bring. There should be plenty of dry times as well as
several hours of wet time as each weather feature translates
through the area.
Took a few degrees off the top of the max temperature on
Saturday and Sunday, especially northern and eastern zones given
the expected frontal positions. Monday should be quite mild in
the upper 70s, and muggy ahead of the cold front with cooler
50s-60s next Tuesday.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
730 pm update...
MVFR across all but RME/SYR now will become mvfr everywhere by
03z. Rain moving into the taf sites this evening with lowering
ceilings and maybe mvfr vsbys. Rain will continue until around
09z. All sites fall to fuel alternate. Ceilings will lower to
IFR between 8 and 14z at AVP/BGM. ELM/ITH may also fall to IFR
same time. Gradual improvement starting 15z so that by 21z all
but AVP/BGM will be VFR.
East winds at 10 kts this evening drop to 5 to 10 kts overnight.
Wednesday afternoon winds shift to southeast.
Outlook...
Wednesday night: No operational impact. WX NIL.
Thursday: Operational impacts possible. Chance TSRA late.
Thursday Night: Operational impacts possible. Chance +TSRA.
Friday-Sunday: Operational impacts possible. Chance SHRA/TSRA
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...DGM/MLJ
NEAR TERM...DGM/MLJ
SHORT TERM...MLJ
LONG TERM...JAB
AVIATION...TAC
Area Forecast Discussion
National Weather Service Billings MT
927 PM MDT Tue Apr 25 2017
.UPDATE...
Weak shortwave in central MT producing some light showers over our
western CWA this evening, but this activity will not amount to
much tonight. Main forecast issue for tonight is fog potential.
Boundary layer moisture remains elevated after our recent
precipitation and courtesy of easterly surface winds. Fog
formation, suggested by the HRRR over our west and in Sheridan
County where abundant snow cover exists, will depend on how much
the low stratus erodes. Current satellite imagery shows a solid
deck along and east of a 3HT-BIL-SHR line, but weak shortwave
passage may help break this up some. Have already added patchy
fog to our west where partial clearing is most likely. Any cloud
breaks in Sheridan County or across far southeast MT should result
in fog fairly quickly. Travel late tonight and early tomorrow may
be affected by fog and locally slick roads as temps fall to or
below freezing across much of the region.
JKL
&&
.SHORT TERM...valid for Wed and Thu...
Current satellite imagery depicts an occluded low over
northeastern Wyoming with associated bands of snow extending into
eastern Montana and the western Dakotas. This evening, 700 mb flow
becomes more northerly as this low moves east of our area, and
snow bands deteriorate from west to east. Hi-res models indicate
modest instability ahead of a weak front over central Montana
could pop up a few showers with some isolated thunder from
Livingston to Harlowton. Areas of fog will be a concern again
tonight and tomorrow morning from the foothills of the Bighorn
Mountains through southern Powder River and Carter Counties.
A shortwave moves into Idaho by Wednesday afternoon carving an
upper trough down into the central Plains. Associated height falls
east of the range will produce a slight chance of showers and
thunderstorms mainly from Billings westward into the central
mountains and foothills. As a second shortwave arrives on Thursday
night, the upper trough becomes negatively tilted with an area of
divergence setting up over most of central and eastern Montana.
This will bring more wet weather to the area through Friday.
Expecting most of the area to see rain or snow with this system,
but given the differences in the models it is too soon to
determine where the heaviest band will setup Thursday night
through Friday. 850 temperatures will hover near the freezing mark
on Friday which means rain/snow mix possible for low-land
locations. Bighorn Mountains will continue their recent trend of
snowy weather with several inches of snow expected each day from
Thur-Sat. Walsh
.LONG TERM...valid for Fri...Sat...Sun...Mon...Tue...
Troughiness over the region on Friday begins to see a broad
circulation spin up over eastern Wyoming which amplifies an
upslope flow into the area. This continues a precipitation event
that begins Thursday with favored areas for precipitation in an
inverted surface trough which lays across the central zones.
Models are beginning to increase the precipitation on the east
side of the Big Horns and trending with colder surface
temperatures. Expect another significant amount of precipitation
to fall especially for Sheridan County and possibly could see some
snowfall. Will have to watch for another winter event but like the
event at the beginning of this week expect the area of impact to
be highly focused. Will continue to be very cold for late April.
Rest of the extended forecast will feature northwesterly flow
aloft as the Friday system ejects but looks drier with slightly
warmer temperatures. Do not expect more significant precipitation
under this regime but showers will be present during diurnal
heating and breezy afternoons. More typical of an April weather
pattern than the previous heavy precipitation events. borsum
&&
.AVIATION...
Expect just some widely scattered rain and snow showers this
evening into the overnight hours. Although low clouds will
persist, ceilings will gradually improve from west to east. The
main impact for the remainder of the night will be areas of fog
and freezing fog developing along and south of an Ekalaka-
Broadus- Hardin line and west of a Roundup-Billings line after
06z. IFR conditions and lower are possible with any fog formation.
Improving conditions are expected by 15z Wednesday with improving
conditions throughout the day. Hooley
&&
.PRELIMINARY POINT TEMP/POPS...
Wed Thu Fri Sat Sun Mon Tue
-----------------------------------------------------------
BIL 032/056 036/048 035/046 034/052 036/059 041/058 039/054
22/R 56/R 66/W 42/W 11/B 33/R 33/R
LVM 030/055 034/048 030/046 027/052 031/056 036/055 033/054
36/T 66/O 57/W 42/W 12/R 33/R 33/R
HDN 030/058 035/050 035/049 034/054 034/061 040/060 039/057
12/R 36/R 65/W 42/W 11/B 33/R 34/R
MLS 027/054 033/054 034/052 036/055 035/061 041/060 040/057
01/B 23/R 55/W 31/B 11/U 33/R 33/R
4BQ 021/046 028/048 033/047 033/051 031/059 039/059 038/056
01/B 13/O 56/W 42/W 11/U 33/R 34/R
BHK 021/049 026/053 028/051 031/053 031/058 036/058 036/056
01/B 11/B 33/W 12/E 11/U 33/R 33/R
SHR 020/049 032/044 031/042 030/047 029/055 036/054 036/052
12/R 46/O 77/W 52/W 11/B 34/R 34/R
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Hastings NE
705 PM CDT Tue Apr 25 2017
.SHORT TERM...(This evening through Wednesday)
Issued at 246 PM CDT Tue Apr 25 2017
Most of the showers from this morning have moved out of the forecast
area this afternoon. Satellite and observations have low clouds
across the area. Temperatures have been fairly stagnant across the
area.
For the remainder of the afternoon, the models have had some
redevelopment in precipitation during the afternoon. The HRRR
actually has precipitation across the far north already, but the
precipitation is moving out rather than developing. Have lowered
PoPs for this afternoon and may have to lower them some more yet.
With the concern for PoPs this afternoon, that also extends into the
evening hours. Without precipitation developing this afternoon,
there may not be much of any this evening either. The only exception
would be in the Kansas counties later tonight. That area may see
some precipitation from the storms to the south. Models are
consistent in moving precipitation out of the area late tonight and
lingering clouds across the area through the night.
On Wednesday, a surface high pressure ridge moves into the forecast
area. This should bring some sunshine to much of the area during the
day. Temperatures will be warmer on Wednesday, but the east may have
a harder time to warm with less sunshine.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 246 PM CDT Tue Apr 25 2017
There are several periods of interest during this period. There is a
frost/freeze potential Wednesday night, potential for precipitation
Thursday through Sunday night, with a couple nights where there
could be a few snowflakes mixed in.
Wednesday night the surface high pressure ridge continues to move
through the area. By Thursday morning, the ridge is centered in the
eastern part of the forecast area. A couple of concerns with this
particular set up. It is fairly safe to say that temperatures will
be quite cold, within a few degrees either side of freezing. The
winds will be light and skies will be mostly clear during the
evening. Then, there becomes a potential problem with the
frost/freeze aspect and even the temperatures could come into
question. Models are starting to bring some clouds into the west.
The GFS even has a little precipitation moving into the west
Thursday morning. The NAM has some warm advection in the west as
well. If that is the case, the temperatures may not be as cold as
forecast, especially in the west.
As the upper level wave moves into the area Thursday, precipitation
will spread across the area. The best chances for precipitation will
be Thursday night into Friday. Friday night into Saturday, the upper
low digs further to the south across the Rockies. There are still a
few waves that come through the area and keep some chances for
precipitation across the area. Friday night into Saturday morning
will be another cool night and there could be a little snow mixed in
with the rain in the far northwest. The low moves into the southern
plains Saturday night and the colder air is pulled into the forecast
area. Temperatures are not very cold, but there is colder air aloft
and there will be some snow mixed in for much of the forecast area
and the far northwest could see some all snow for a time late
Saturday night into Sunday morning. The upper low takes a track
toward the north northeast on Sunday and Sunday night. The chance
for rain continues Sunday and finally comes to an end Sunday
evening.
There will be a quick break from late Sunday night mostly through
Monday night. There may be a few showers Monday afternoon in the far
north, but most of the time should be dry. The next upper level wave
will move in Tuesday and there is a chance for some showers Tuesday
afternoon. Temperatures Monday and Tuesday should rebound back
towards normal for this time of year.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday evening)
Issued at 652 PM CDT Tue Apr 25 2017
Ceilings are expected to remain low throughout the overnight
hours, likely IFR through most of tonight. The wind will remain
consistently breezy out of the northwest through tonight and
tomorrow.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...JCB
LONG TERM...JCB
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Lincoln IL
853 PM CDT Tue Apr 25 2017
.UPDATE...
Issued at 845 PM CDT Tue Apr 25 2017
Latest surface map indicates a frontal boundary over east central
Iowa with several waves of low pressure riding along it. The
better moisture and instability this evening is located over parts
of southwest Missouri south through Oklahoma where strong convection
was ongoing this evening. The 00z ILX sounding continues to show
quite a bit of dry air in place across central Illinois with surface
dew points as of 8 pm in the upper 40s to lower 50s. As the evening
wears on persistent low and mid level warm advection and moisture
transport coupled with shortwave energy pushing out of the Southern
Plains will lead to an increasing chance for showers and thunderstorms
over extreme west central Illinois late tonight. Last several runs
of the HRRR model indicates the first wave of showers to affect mainly
our far western counties around Midnight, with a second cluster of
storms forecast to track northeast out of Missouri towards dawn
Wednesday.
Looks like an active weather day over central Illinois tomorrow
as the front slowly edges its way east during the day. The
combination of strong deep layered shear and decent instability
may bring about strong to locally severe storms, especially tomorrow
afternoon and evening. Precipitable water values of well over an
inch will bring about the additional threat for heavy rainfall to
central Illinois where 1 to 2 inches of rain is not out of the
question. The storms will tend to track from southwest to northeast
along the slow moving frontal boundary enhancing the threat for
heavy rainfall, especially tomorrow evening.
No major changes were made to the grids this evening with respect
to timing of the showers into the west towards Midnight. Southerly
winds and cloud cover will keep it rather warm overnight with most
areas not dropping below 60 degrees which is reflected in the current
ZFP. As a result, no evening update will be needed.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 303 PM CDT Tue Apr 25 2017
Gusty south winds will continue into this evening, as a cold front
approaches from the west. Low level moisture will be on a steady
increase tonight, with the cold front expected to reach near the
Mississippi River by 12z/7am Wednesday. Scattered showers and a
few thunderstorms will be possible late tonight, mainly west of
the Illinois river, but possible as far east as the I-55 corridor.
Better chances of rain will begin Wednesday afternoon as the cold
front pushes to near I-55. Instability and wind shear parameters
look favorable for some severe storms to develop late Wed
afternoon, with damaging winds the primary threat, and large hail
also possible.
.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 303 PM CDT Tue Apr 25 2017
The extended forecast will start out Wednesday evening with a
squall line moving from SW to NE across central Illinois, roughly
along the I-72 corridor. The NAM is even hinting at multiple
squalls training over the same areas, which would ramp up the
potential for flash flooding. Instability appears to drop off by
03z, so severe threat should be mainly from late Wed afternoon to
mid evening.
The cold front will push into Indiana by sunrise on Thursday, but
showers are expected to linger Thursday morning. Dry conditions
should return for Thursday afternoon as cooler air arrives on NW
winds. Highs will be limited to the upper 50s and low 60s, or
about 15 to 20 degrees cooler than Wednesday`s highs.
Attention then turns to an extended period of wet weather from
Friday through Sunday night. The first wave or rain looks to
arrive Friday morning and continue through the day. There are some
model differences as to the location of the warm front as a
shortwave moves across southern Illinois. The better chances of
heavy rainfall appears to set up after midnight Friday night and
continue through Saturday night. The system will be driven by a
deepening upper level trough in the Plains on Friday, with a
surface low eventually ejecting into far NW Illinois by Sunday
afternoon. Copious amounts of moisture are projected to surge into
Illinois ahead of the system as it occludes and slowly drifts
northeast toward the western Great Lakes this weekend. While the
potential for severe storms in Illinois will be marginal, several
periods of heavy rainfall could push rainfall totals between 2 to
4 inches in much of central and southeast Illinois. The highest
totals look to be along and south of I-70, but model adjustments
over the next few days should provide better clarity on the axis
of heavy rainfall.
We continued the Hydrologic Outlook for the potential for heavy
rainfall and flooding with the combination of locally heavy rains
Wednesday/Wed night in addition to the heavy rains Friday through
Saturday night. While showers continue on Sunday under the
occluding low, the potential for heavy rains should diminish by
Sunday morning as dry air wraps into the upper low, leaving a more
shallow saturated layer.
Dry conditions should close out the extended forecast for Monday
and Tuesday. Monday will be noticeably cooler, with highs similar
to Thursday, in the upper 50s to low 60s. A warming trend will
develop for Tuesday, as increasing sunshine helps boost high temps
into the upper 60s to around 70.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 620 PM CDT Tue Apr 25 2017
VFR conditions are expected through this evening with a gradual
deterioration in cigs in the 09z-12z time frame at PIA as several
bands of showers and thunderstorms track across the area. It
appears the first round of showers will affect mainly PIA by
08z with VCSH mentioned at SPI and BMI with our eastern TAF
sites not seeing any precip until after 11z. The gusty south
to southeast winds will continue for the next few hours with
a decrease in the gustiness after 04z. The second round of
showers and storms looks to push into the TAF sites starting
between 10z and 12z and this band looks to be the one to lower
the cigs even in our eastern TAF sites to low VFR and MVFR
category during the morning. Southerly winds late tonight
into Wednesday morning will trend more southwesterly over
in PIA as a cold front approaches the area late in the TAF
period. Wind speeds will range from 12 to 17 kts with gusts
up to 23 kts at times, especially east of the I-55 corridor.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Smith
SHORT TERM...Shimon
LONG TERM...Shimon
AVIATION...Smith
Area Forecast Discussion
National Weather Service Little Rock AR
931 PM CDT Tue Apr 25 2017
.DISCUSSION...
Convection continues to fire up in NE OK at this time as the upper
trough/cold front continues to advance into that part of the state.
Upper flow remains parallel to the convection keeping the overall
movement of these storms on the slow side as they drift off to the
NE.
All short term models, most noticeably the HRRR, show this area
moving into NW AR during the night and clipping our NW most
counties. Pops raised in this area accordingly but it looks like
the storm movement being what it is will preclude the need to go
much further into the CWA at this time. While HRRR is cranking
out some very impressive rain totals, the heaviest amounts will
likely stay out of our CWA as the precipitation battles mid level
dry air.
&&
.PREV DISCUSSION...(ISSUED 630 PM CDT Tue Apr 25 2017)
AVIATION...
Moisture will continue to increase across the area in advance of
an approaching storm system with occasional MVFR to possible IFR
conditions developing by early Wednesday morning. Winds will stay
elevated as the pressure gradient remains tight in advance of the
aforementioned storm. As a cold front moves through the area, a
line of strong to possibly severe thunderstorms is expected with
gusty winds,low ceilings and a wind shift to the NW.
PREV DISCUSSION...(ISSUED 247 PM CDT Tue Apr 25 2017)
SHORT TERM...Tonight Through Thursday
Current surface analysis shows a frontal boundary extending from
southeast Kansas into the Texas Panhandle region. Boundary has
stalled slightly, but as the first of two upper troughs associated
with a low over the Rockies kicks out and amplifies the upper
flow. This system will kick off showers and thunderstorms ahead of
the front by late tonight, with a second system behind it
providing the support for showers/storms over Arkansas on
Wednesday.
Parameters are coming together for severe thunderstorm potential
for Wednesday afternoon and evening, with a risk for severe storms
over not only the entire forecast area but the entire state. Any
severe storms will be capable of producing large hail and
damaging winds. Though there will be a bit of a cap initially,
strong low level jet dynamics, along with good moisture transport
into the region should be enough to destabilize things a bit.
Given the amount of low level wind shear present, there will be a
tornado risk.
Expected storm mode would be discrete cells initially, with a line
of storms developing along and ahead of the front. Tornado threat
would be highest with the cells out ahead of the front, and
primarily during the afternoon and early evening hours.
Stronger storms will be capable of producing localized heavy
rainfall. On the whole, an inch or two of rain looks like a good
bet for much of the state from this system, but heavier cells
could allow for higher amounts in localized areas.
As far as timing, the threat for severe storms in western Arkansas
will primarily in the early to mid afternoon hours, while the
central portion will see the highest threat from mid to late
afternoon through early evening, and the eastern portion from
late afternoon through late evening.
Front will clear the state during the overnight hours. Although
there will be a brief shot at precip over northern Arkansas behind
the front, rainfall should largely be over by Thursday morning.
Cooler airmass will follow the front, albeit briefly. Frontal
boundary will stall out well south of the region on Thursday,
before coming back north and starting trouble for the end of the
week and into the weekend.
More on that from the long term forecaster...
LONG TERM...Thursday Night Through Tuesday
Warm front will be moving northward across the area during the day
on Friday, bringing an impressive surge of low level Gulf moisture
across the area.
For the past several days we have been talking about the potential
for severe weather, and possible tornadoes, on Friday. As the warm
air flows northward, low level winds should be predominantly south
to southeast. Right off the deck the 850 winds will be strong out of
the southwest, with a 40-50 kt low level jet. This will set up
strong low level wind shear. Moving further aloft, 500 mb winds will
be continuing from the SW with some speed shear present.
Typically I would be concerned about the 850 mb winds from the SW
coming out of TX introducing drying air. However in this particular
case it appears there will be abundant Gulf moisture over TX, so
this will not be a factor.
At the 500 mb level the models are showing a closed low digging down
into the swrn US, with a swly flow aloft. The models are not really
resolving much at this range, but I think it would be reasonable to
suspect that a few minor shortwaves will kick out across the area
during this period.
So let`s talk severe weather potential for Friday. I certainly have
a lot of concerns, especially across the western zones. It looks
like convection will fire in those areas more or less in the daytime
hours, where greater levels of low level instability will be
present. Model soundings showing CAPE values in the range of 2000-
3000 j/kg with just a bit of a cap. With the strong low level shear
in the lowest few thousand feet, I`m am concerned about the
potential for rotating supercells. As things evolve throughout the
day, I strongly suspect this will turn more into a line that moves E-
NE and will become more of a wind and hail event.
By Saturday a cold front will be moving in from the west, although
this front will be moving rather slowly. Once again, I can
envision the potential for discrete cells ahead of a squall line,
although with the trof digging across the swrn US, and the upper
flow becoming more southerly, the low level shear will not be as
great. For the most part I think this will be more of a squall
line event, along a slow-moving front, with cells training N-NE
along the advancing front.
By mid-late Sunday morning most of the convection should be pushing
out of the eastern parts of the forecast area, although some models
do show the front continuing to stall just a bit longer.
Setting aside the severe weather risk, the big issue will be
rainfall accumulations from Friday through Sunday. Deep moisture
will be present from the low levels all the way thru the top of the
troposphere. This will result in thunderstorms producing heavy rains
on Friday, followed by slow moving storms and a training effect on
Saturday and Sunday.
Model QPF guidance has been fluctuating a bit, but overall I would
not be surprised to see widespread 4" storm total amounts across
wide areas, with some areas topping out in the 6 to 8 inch range,
and possibly even higher. If this much rain falls, it will
undoubtedly cause a major flooding problem along area rivers.
Contingency forecasts are showing many rivers and tributaries
swelling into moderate to major flood categories with this much
rainfall.
FIRE WEATHER...
Winds will remain elevated through Wednesday, as a cold front
approaches and moves through the region. Scattered to numerous
showers and storms are expected along and ahead of the front, with
dry weather behind it on Thursday. More storms, as well as heavy
rainfall, are expected for the weekend.
&&
.LZK Watches/Warnings/Advisories...NONE.
&&
$$
56
Area Forecast Discussion
National Weather Service Marquette MI
753 PM EDT Tue Apr 25 2017
.SHORT TERM...(This evening through Wednesday)
Issued at 400 PM EDT TUE APR 25 2017
WV imagery and RAP analysis indicated sw mid/upper level flow from
the srn plains to the nrn Great Lakes ahead of a trough from the
cntrl into the srn Rockies. The first of several shortwave troughs
lifting to the northeast supported a band of showers over srn MN
into sw WI. another upstream shrtwv was moving through KS. At the
surface, se winds prevailed across the cwa ahead of the a
trough/front from wrn Lake superior to the sw to low pressure ove
OK.
Tonight, expect sct shra to move into mainly the wrn half of Upper
Michigan this evening, per satellite/radar trends and short range
models. However, rain will become more widespread and heavier
overnight over the west as the KS shrtwv moves toward the area and
moisture transport and 300k-305k isentropic lift increases. 850 mb
dewpoints to around 10C and PWAT values to near 1.4 inches will
support moderate to locally heavy rain with QPF into the 0.50-0.75
inch range.
Wednesday, heavier rain will linger into the morning with additional
moderate to heavy amounts until mid level drying moves in during the
afternoon as the sfc low lifts into the area. Although the pcpn
coverage/intensity may diminish, higher POPs will continue with
sct/nmrs showers. There may be enough elevated instability over the
s and se in the afternoon for potential over isold tsra. Otherwise,
temps will climb into the upper 50s and lower 60s over the se 2/3
but remain around 40 over the west behind the slowly advancing front.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 342 PM EDT TUE APR 25 2017
Main concerns in the long term will be light wintry mix Wednesday
night into Thursday along with increased river levels through
Thursday night.
Wednesday night through Thursday night: Low pressure sliding through
the Upper Great Lakes region is expected to slide directly across
the central U.P. Wednesday night to near James Bay Thursday night.
At the same time, a close 500mb low is progged to slide across the
Northern Plains into the western part of the CWA. The better chances
for precipitation will occur Wednesday night and again during the
day Thursday into Thursday night as 1000-500mb RH is in place and
deep layer forcing is maximized through that layer. There will be a
gradual diminishing trend from the southwest Thursday evening into
the overnight hours. Overall, the precipiation should remain in the
form of rain across most of the U.P.; however, as the upper level
low drops into the far western CWA, colder air will allow the
precipitation to transition to a mix of rain, freezing rain, sleet
and snow especially Wednesday night. Ice and snow accumulations are
expected to be limited and generally confined to elevated surfaces
and grassy surfaces. The accumulation will largely be limited due to
the warmer surfaces, as temperatures have generally been above
normal over the past few days. Otherwise, rainfall totals are
expected to be between a half an inch and three-quraters of an inch
through this time period, with the heaviest totals expected over the
east. This additional rainfall along with the expected rainfall
through Wednesday will keep river levels elevated through this time
period, as previous shift mentioned at least minor flooding is not
out of the question through Thursday night.
Friday through Saturday: A surface ridge and drier air is expected
to build into the area during this time period allowing skies to
become partly cloudy with only minor chances for rain and snow
showers. Temperatures are expected to be slightly below normal
through this time period.
Saturday night through the extended: Low pressure is expected to
develop over the Southern Plains late Saturday night and slide
through the Upper Great Lakes Sunday into early next week. Models
are in generall agreement; however, there are some timing and
placement differences in the solutions. The GFS/Canadian have
similar tracks and timing; however, the GFS is deeper with the
surface low and upper level low. These models each have the low
moving out of the area Tuesday afternoon. The previous run of the EC
was much faster with the low having the system out of the area by
Monday afternoon; however, the 12Z run has the timeing similar to
the GFS/Canadian. The EC is continues to trend farther west with the
system. If the GFS/Canadian are correct there could be accumulating
snowfall across the west half of the U.P.; however, if the EC
solution is correct, then most areas may end up seeing mainly rain.
this will definitely need to be watched in later forecast packages,
at this point will stick with a consensus of the models bringing
widespread precipiation to the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 752 PM EDT TUE APR 25 2017
A sfc trof drifting se over Upper MI tonight and then stalling out
will result in deteriorating conditions as showers develop and low-
level moisture increases significantly. Expect IFR conditions at
KIWD by late evening and at KCMX/KSAW overnight. Cigs will likely
drop to LIFR at times, becoming prevailing LIFR at KSAW late in the
night and at KCMX/KIWD during Wed.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 400 PM EDT TUE APR 25 2017
Northeast gales will being over west and central Lake Superior this
evening and continue through Wed evening. By late Wednesday night
into Thursday morning winds will begin to subside to 20 to 30 knots
as winds become northerly. Late Thursday through Friday, winds will
further decrease to 10 to 20 knots as winds become westerly. Winds
of 10 to 20 knots are expected through the weekend and into early
next week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning until 11 PM EDT /10 PM CDT/ Wednesday for LSZ162.
Gale Warning until 3 AM EDT Thursday for LSZ264.
Gale Warning until 2 AM EDT Thursday for LSZ263.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...KEC
AVIATION...Rolfson
MARINE...JLB
Area Forecast Discussion
National Weather Service Mount Holly NJ
945 PM EDT Tue Apr 25 2017
.SYNOPSIS...
Low pressure will track northeast just off the Delmarva and New
Jersey coastline through Wednesday. Meanwhile, low pressure will
move from the upper Mississippi Valley into James Bay, and send a
weak cold front into our area Thursday night and Friday morning.
A backdoor front is expected to move through the region Saturday
evening. Another low pressure system moving from the lower Plains
into Quebec and its associated fronts will affect the area Monday
into Tuesday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
The water vapor imagery as of 01z shows the center of a well defined
closed low just exiting the northeast coast of North Carolina. An
area of heavier rain is moving across central to northern New Jersey
with precipitation more showery to the south and west. Some
lightning continues near and east of the closed low center, and a
mesoscale analysis shows the axis of instability offshore although
there is some MUCAPE across the southern half of our area. The
lightning has been maintained offshore in the axis of higher
instability, which is also more surface-based there. Since this
should mainly stay offshore, removed thunder for our area. Made
adjustments to the hourly temperature, dew point and wind grids to
keep them current. Adjusted the PoPs based on radar trends and some
assistance from the HRRR guidance, with highest values across the
northern areas awhile longer. Transitioned the precipitation over to
showers as this looks to be the mode over much of the area. However
given the low celings and wealth of low-level moisture, some drizzle
can occur outside of the showers.
With abundant low-level moisture in place, stratus will be
maintained and some forecast soundings show the inversion lowering
some overnight. In addition, some fog is anticipated however how
widespread it becomes or dense is a forecast challenge. The stratus
may dominate, however we will continue with a fog mention although
not anticipating the need for a Dense Fog Advisory at this time.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
Low pressure off the NJ coast will continue to drift to the north on
Wednesday. Upper level low will be just to the west of it, and with
several strong shortwaves passing through the region, can expect
some showers throughout the day. Otherwise, fog gradually dissipates
through the morning, but clouds will remain across the region for
most of the day. Winds back a bit to the N/NW by afternoon, but the
gradient will be light, and winds will remain less than 10 MPH.
Highs generally top off in the 60s, but a few spots may come close
to 70.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Overall - Warm pattern shaping up. The closed low that is
currently over the southeast US finally exits the area early
Wednesday night. With the polar jet displaced far to the north,
several disturbances traversing the southern stream jet will aid
in building a stout sub tropical ridge off the southeast US
coast from Friday into the early part of next week. As another
closed low ejects out of the midwest on Monday, a stronger and
more active cold frontal passage occurs in the late Monday into
early Tuesday period.
Wednesday night into Thursday should feature dry weather under brief
ridging aloft. With some partial clearing Wed night, light and
variable winds within the col between weather systems, and
abundant low-level moisture given recent rainfall, patchy fog is
likely. The fog will burn off early Thursday, with partly sunny
skies expected. A light southeast flow will maintain cooler
temperatures at coastal locals. Highs will be around 10 degrees
above normal.
A weak cold frontal passage Thursday night into Friday will lead to
considerable cloudiness, but moisture will be limited, with only a
slight chance of showers across the region. In fact, with the strong
subtropical high building over the southeast/orientation of the mid-
level flow, this front is expected to washout/stall in the
vicinity of the I-95 corridor. With deeper moisture and mid-
level support exiting the region, expect a return to partly to
mostly sunny skies by Friday afternoon. A weak synoptic flow
should encourage a robust sea breeze. Highs will be several
degrees warmer than Thursday, around 15 degrees above normal,
but far from daily record highs.
Clouds increase again Friday night into Saturday with another cold
front moving toward the region. There is considerable uncertainty
regarding the timing of this front, with model solutions varying
from Saturday morning to Saturday night, with a backdoor component.
In addition, there is also uncertainty regarding the precip
potential, with quite a bit of spread amongst the model
solutions. For now, we maintained chance PoPs, including thunder
on Saturday. Kept thunder out of the forecast for Sunday given
more stable maritime airmass, except Delmarva, with closer
proximity to the frontal boundary. Still some uncertainty with
high temperatures on Saturday, which will be dependent on the
location of the front, but expect them to be similar to Friday.
There is model agreement that the front will be just to our south-
west on Sunday, with the area under the influence of a northeast low-
level flow. This would favor a stratocumulus deck and perhaps some
sprinkles, mainly across the higher terrain. Kept thunder out of the
forecast for Sunday given stable maritime airmass, except Delmarva,
with closer proximity to the frontal boundary. High temps still be
several degrees above normal.
Moving into early next week, more showers and thunderstorms likely
Monday and Monday night with the next cold frontal passage. Expect a
return to drier weather on Tuesday. Continued above normal
temps.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Overnight...IFR, locally LIFR, ceilings. Some fog/drizzle especially
late will result in times of IFR, perhaps LIFR, visibilities
although the extent and timing is less certain. Showers will
continue for awhile, but taper off from southwest to northeast
overnight. Northeast winds 10-15 knots with local gusts up to 20
knots, diminishing to 10 knots or less.
Wednesday...IFR/LIFR in the morning due to low clouds and some fog,
then conditions slowly improve to IFR/MVFR in generally the 15-18Z
timeframe. Isolated to scattered showers are possible especially
through midday. Northeast to north winds mainly 5-10 knots.
OUTLOOK...
Potential for fog leading to visibility restrictions Wed night
and MVFR ceilings persisting into Thursday. Predominantly VFR
Thursday night into Saturday. MVFR possible in low clouds Sat
night into Sunday.
&&
.MARINE...
The Small Craft Advisory for Delaware Bay is cancelled as winds are
diminishing. The Small Craft Advisory for the ocean zones continues
through Wednesday night, as winds diminish overnight from south to
north however it should take awhile for the seas to subside.
Some fog is expected to develop overnight with local visibility less
than 1NM possible, however it is possible this becomes widespread
enough for a Marine Dense Fog Advisory. The fog dissipates during
Wednesday morning.
OUTLOOK...
SCA-level seas likely persist through Friday with a return to
sub-SCA conditions thereafter.
&&
.TIDES/COASTAL FLOODING...
The Coastal Flood Advisory remains in effect for coastal areas of
New Jersey and Delaware, including Delaware Bay, and for the far
lower part of the Delaware River.
Low pressure located over eastern North Carolina this afternoon will
drift northeastward reaching the waters off Delaware and New Jersey
on Wednesday. The tight gradient and resulting brisk onshore flow
will remain along the coasts of Delaware and New Jersey into this
evening before wind speeds begin to diminish.
The surge around this morning`s high tide ranged from +0.5 to +1.0
foot along the Delaware and New Jersey coasts. Based on the trends
this afternoon and on the forecast guidance it appears as though the
surge will be mostly in the +1.0 to +1.5 foot range for this
evening`s high tide. The surge is expected to result in widespread
minor flood in coastal areas of Delaware and New Jersey and along
much of Delaware Bay. Localized minor flooding is anticipated on the
far lower part of the Delaware River.
It appears as though the tidal Delaware River above the Commodore
Barry Bridge area may just reach the minor flooding threshold.
However, the impacts should not be widespread enough there to
warrant a Coastal Flood Advisory.
We are not anticipating any coastal flooding along the upper eastern
shore of Chesapeake Bay.
The diminishing wind overnight along with the lower astronomical
tides on Wednesday morning should preclude another round of minor
flooding with Wednesday morning`s high tide. We will keep an eye on
the higher astronomical tides on Wednesday evening. If the water
does not drain away from the coast fast enough, we could see some
localized minor flooding at that time.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Advisory until midnight EDT tonight for
NJZ012>014-020>027.
Coastal Flood Advisory until 1 AM EDT Wednesday for NJZ016.
DE...Coastal Flood Advisory until midnight EDT tonight for
DEZ002>004.
Coastal Flood Advisory until 1 AM EDT Wednesday for DEZ001.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ450>455.
&&
$$
Synopsis...Franck
Near Term...Gorse
Short Term...MPS
Long Term...Franck/MPS
Aviation...Franck/Gorse
Marine...Franck/Gorse/MPS
Tides/Coastal Flooding...Iovino
Area Forecast Discussion
National Weather Service Blacksburg VA
1156 PM EDT Tue Apr 25 2017
.SYNOPSIS...
Low pressure centered over the eastern North Carolina will slowly
drift northeast and off the coast tonight into Wednesday. High
pressure will build in Wednesday and continue for the second
half of the week. This will result in a considerable boost to
the temperature with above seasonal warmth expected by the
weekend.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 950 PM EDT Tuesday...
Patchy sprinkles across parts of the mountains are continuing to
a decreasing trend on radar, and there are few reports within
the surface observations. Bluefield, WV had some light rain a
little while ago. The latest report is from Hillsville, VA.
Little if any sprinkles are expected to survive after midnight
as cloud cover starts to erode across western sections of the
region first. With winds becoming light and variable or calm,
plenty of surface moisture, and clearing skies, we are
anticipating fog development to be common across the region
overnight. Have tweaked hourly temperatures and dew points based
upon the latest observations and expected trends into the early
morning hours of Wednesday.
As of 640 PM EDT Tuesday...
The low pressure system that has affected the entire area through
this past weekend is situated over the North Carolina coast and is
forecast to slowly move out of the area during the overnight hours.
Currently on radar, areas are seeing some lingering drizzle that
will make way to patchy fog in the morning hours before clearing out
for the day on Wednesday. Most recent solutions of the HRRR and RAP
models show precipitation ending sooner in the Piedmont with only a
few lingering sprinkles along and west of the Blue Ridge
Mountains. Therefore, have adjusted the forecast accordingly.
As of 255 PM EDT Tuesday...
WSR-88D showed showers are diminishing or dissipated across
most of the forecast area. However, there are still some pockets
of drizzle and light rain. Low pressure centered over eastern
North Carolina this afternoon will move northeast off the
Atlantic coast tonight into Wednesday. High pressure over the
Ohio Valley will build east tonight into Wednesday.
HRRR and Hiresw-arw-east try to develop some isolated showers across
the high terrain this afternoon into this evening. Believe any
shower or light rain/drizzle will be limited. Mid level ridging
builds in from the west this evening into tonight. For tonight, any
clearing will set the stage for fog formation. Unless the stratus
persists, anticipate development of fog per wet ground, diminishing
winds and radiational cooling from the departing mid/upper level
cloud cover. Low temperatures tonight will range from the mid 40s in
the mountains to the lower 50s in the Piedmont.
High pressure will build over the Southeast States Wednesday. Any
fog Wednesday morning will quickly dissipate leaving sunshine for
Wednesday afternoon. With increasing heights and warming
thicknesses, 85h temperatures will climb to near +15 deg C for
Wednesday. Temperatures may be a degree or two cooler than one would
think, as the initial surge of warmth will go into latent heating
and an attempt to evaporate all of this moisture laying around from
the multiday rain event. High temperatures will vary from near 70 in
the mountains to the upper 70s in the Piedmont.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 258 PM EDT Tuesday...
A low amplitude upper ridge will give way to a broad trof over the
upper midwest with short wave shearing off to our northwest. This will
drive a surface low from the Great Lakes into Canada and drag a
trailing cold front into our region late Thursday into Thursday night
with basically high chance POPs for scattered showers/some thunder.
High pressure brings us a basically dry day for Friday before a warm
front lifts north through the region Friday night with chance for
showers/storms.
By Friday, we develop a Bermuda high off the coast with ridging aloft
and a deepening trof/closed low over the midwest. This will develop a
deep southerly flow of warm and moist air that will pump the heat and
humidity up by late in the week. Expect highs Friday to reach the mid
80s east of the Blue Ridge with upper 70s/lower 80s to the west.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 258 PM EDT Tuesday...
We will be in a very summerlike pattern this weekend with very warm and
humid conditions and an increasing chance for showers and thunderstorms
each day, especially along the Blue Ridge. By Monday, the vertically
stacked upper closed low over the midwest will move into the Great
Lakes region. This will push a vigorous cold front into the area from
the west with a good chance of showers and thunderstorms through Monday
afternoon. High pressure will then build on for Tuesday with cooler
weather and windy conditions.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
As of 730 PM EDT Tuesday...
MVFR ceilings with pockets of IFR, light rain, drizzle and fog
will continue until about midnight. The upper level low will
slowly drift northeast tonight and away from the area Wednesday.
The pressure gradient across the region will start to weaken,
allowing winds to become light and variable overnight into
Wednesday morning.
Areas of low clouds and fog will develop tonight with IFR conditions
expected into Wednesday morning. Conditions will become VFR by
Wednesday afternoon. Winds will remain light and variable.
Moderate confidence in ceilings, visibilities and winds during
the TAF period.
Extended Aviation Discussion...
Better flying weather is expected for the second half of the
week, though another front may bring scattered MVFR
showers/storms Thursday afternoon and evening across the
mountains. Drier and much warmer weather will return for Friday
and Saturday with temperatures much above normal for the
weekend. Can not completely rule out an isolated MVFR
thunderstorms along the southern Blue ridge. Scattered MVFR
showers and thunderstorms are possible Sunday and Monday.
&&
.HYDROLOGY...
As of 1145 PM EDT Tuesday...
The upper low has finally moved out of the area and any
remaining precipitation is generally in the form of drizzle.
Additional QPF from this synoptic system will no longer be a
factor. Main concern at this point is runoff into the lower end
of the Dan and Roanoke River basins. Coordinating with SERFC and
AEP, expected water releases from Smith Mountain Lake and
Leesville Reservoir will be insufficient to push Alta Vista or
Brookneal into flood stage, and in fact, the river at both of
these locations is already falling and is just at action stage
at this point. Further downstream at Randolph on the Roanoke,
flooding will continue for a couple more days and the river will
just touch moderate flood stage by Wednesday afternoon.
More significant concerns along the lower end of the Dan River
continue and will for a couple more days. The river has crested
at Danville, just a tad under major flood. At Paces, the
situation is a bit more serious as the river is now forecast to
crest near 28.6 feet, well above the major flood level. Viewing
the crest history, this is only the 9th time of record that the
river has crested in the above the major flood level. Finally at
South Boston, the current forecast has it cresting just below
major flood. It is interesting to note that most of the previous
major floods were associated with a tropical system, such as
Hurricane Agnes in 1972 or Hurricane Fran in 1996.
Will also continue the Areal Flood Warning for a bit longer
along the upper reach of the Dan River due to continued flooding
at points such as Wentworth, NC.
For additional details on the river flooding, please refer to
the AHPS page and specific FLS/FLWs issued from this office.
As of 258 PM EDT Tuesday....
Significant rainfall has ended across the region allowing water levels
to gradually subside at all locations except along the Dan and Roanoke
rivers.
The Dan is expected to crest early tonight above major flood stage at
Danville, then begin falling later tonight. Crests at Paces and South
Boston are not expected until late Wednesday. Further upstream, the Dan
crested at moderate flood stage at Wentworth and will be falling slowly
overnight.
The Roanoke river at Randolph will experience moderate flooding with a
crest late tomorrow.
Please refer to the latest flood statements for further details.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...KK
NEAR TERM...DS/KK
SHORT TERM...MBS
LONG TERM...MBS
AVIATION...DS/KK/PM
HYDROLOGY...MBS/PM/RAB