Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/16/17
Area Forecast Discussion
National Weather Service La Crosse WI
535 PM CDT Sat Apr 15 2017
.SHORT TERM...(Tonight)
Issued at 315 PM CDT Sat Apr 15 2017
Impactful weather concerns include thunderstorms/heavy rainfall
potential through the evening.
The short term forecast remains quite complex this evening ahead of
a cold front that will swing through this evening. Overall forecast
thinking remains similar to previous update, with still some
questions on the placement and coverage of convection late this
afternoon and this evening. A band of showers extending northeast
from convection across central Iowa along a low-level convergence
axis ahead of the cold front has kept much of the area on the
cloudy side through mid afternoon.
Instability has been slow to increase with the cloud cover so far.
Favorable deep layer shear of 35-45 kts will aid in storm
organization while 0-1 km and 0-3 km shear is expected to be
highest over far northeast Iowa into southwest Wisconsin.
Convection is expected to increase with the approach of the
front/shortwave late this afternoon/evening. Recent runs of the
HRRR have suggested a focus of convective development across
central/eastern Iowa, and possibly becoming more linear through
the evening as storms consolidate and encounter stronger low-
level shear. Another boundary draped from southeast Minnesota into
central Wisconsin could potentially help fire storms. However,
given the muddled surface pattern and ongoing showers extending
into northeastward into the area, confidence on convective
evolution and degree of severity is not high.
If vigorous storm development does occur over the area, initial
storms will pose a hail risk potentially evolving into a wind
threat should storms organize over the area. Following last
night`s rains and saturated soils, locally heavy rain remains a
concern. Any areas that experience repeated storms, given a moist
environment with precip water around 1.2 inches, could see
localized flash flooding. This would especially be the case in
areas that saw heavier rainfall last night. See the hydrology
section for more details.
Storms will exit late this evening as the cold front pushes through.
.LONG TERM...(Sunday through Saturday)
Issued at 315 PM CDT Sat Apr 15 2017
There will be a respite from the wet weather Sunday and Monday with
dry high pressure over the region. With plenty of sunshine expected
and good mixing to around 800 mb, temps should easily rise into the
60s on Sunday. The mixing should allow for some wind gusts in the 20-
30 mph range as well. A shortwave trough will pass north of the area
on Monday with upper ridging building into the Midwest into Monday
night. Seasonably mild temps in the 60s to perhaps near 70 and
lighter winds are expected for Monday.
The active pattern will resume beyond Monday as another upper wave
approaches on Tuesday. Moisture transport will increase ahead of an
approaching cold front set to pass through Tuesday
afternoon/evening. This will bring another good chance for rain and
possibly thunderstorms to the region. While the global models are in
reasonably good agreement with this system with placement/timing,
the degree of instability is uncertain, with current model runs
keeping the greater instability to the south.
The 15.12Z GFS and GEM, and 15.00Z ECMWF have come into agreement on
bringing a vigorous shortwave through the region late Wednesday into
Thursday, with the attendant surface low tracking from southwest
Iowa towards southern Lake Michigan. This system could pose multiple
hazards for our area:
1) Widespread rainfall amounts of +1" on ground that absolutely
cannot take any more moisture
2) Thunderstorms, mainly south of I-90; confidence in severe
potential is very low at this time
3) Potential for snow on the backside of the surface low as it
departs Thursday night, mainly north of I-94; confidence on this is
also low, and any accumulations would likely be little to none given
warmer surfaces
While details are certain to change, this system will need to be
monitored closely. Models are then in fair agreement on a positively-
tilted longwave trough gradually shifting eastward across the
central CONUS Friday into Saturday, with a surface low passing by to
our south and east.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 535 PM CDT Sat Apr 15 2017
Cigs: mostly vfr tonight, although some dip into mvfr with any
shra/ts possible this evening. The clouds are expected to sweep east
by early Sun morning - before 12z, with mostly sct/skc conditions
through the rest of Sunday.
One caveat is the potential for a few hour period of mvfr post the
shra/ts threat and before the cold front moves through. Meso models
RH fields and bufkit soundings hint at this, although not seeing
much in the sfc obs yet. Going to keep forecast VFR for now, but
monitor.
WX/vsby: Scattered shra/ts through about 03z, with most of the
activity holding south of I-90. The stronger storms will produce
heavy rain, stronger wind gusts and potentially small hail. Expect
vsby reductions with any storm.
Winds: Enhanced wind gusts around any storm, otherwise winds will
swing to the northwest post a cold front, before 06z tonight. Daytime
mixing should bring some gusts to the TAF sites for Sunday
afternoon.
&&
.HYDROLOGY...
Issued at 315 PM CDT Sat Apr 15 2017
Elevated river levels will be a major concern through the entire
forecast period. Widespread rain totals of 1 to 3 inches over the
past 24 hours have caused many area rivers to respond, and 2 river
sites may approach minor flood stage by Sunday afternoon. Additional
showers and thunderstorms are likely in 3 distinct waves: 1) this
afternoon into tonight, 2) Tuesday, and 3) late Wednesday into
Thursday. Each of these systems will have the potential, if
ingredients come together, to produce swaths of +1" of rainfall,
with localized higher amounts. With soil moisture currently at the
99th percentile across the area, any additional rainfall will create
issues. In addition to localized flash flooding, river flooding
and mudslides will be possible should the forecast rainfall
materialize.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...JM
LONG TERM...JM/MH
AVIATION...Rieck
HYDROLOGY...MH
Area Forecast Discussion
National Weather Service Binghamton NY
1120 PM EDT Sat Apr 15 2017
.SYNOPSIS...
On Sunday a cold front will pass through the region with a more
widespread round of showers and thunderstorms for our area
mainly during the afternoon and early evening. High pressure
builds into our area for early next week with dry and cooler
weather.
&&
.NEAR TERM /THROUGH SUNDAY/...
Updated at 915 pm. Showers are moving southeast of the Poconos
late this evening and are also passing just to to the northeast
of Oneida county. Expecting a dry overnight period with clear to
partly cloudy skies and temperatures settling down in the 50s.
Previous discussion is below.
Updated at 630 pm. Just a quick grid update to account for the
latest trends. Area of showers is rapidly weakening and moving
off to the east early this evening. Scattered showers will still
affect the area from the Catskills through northeast Pa until
around 8 pm... then expect a mainly dry overnight. Temperatures
will be mainly in the 60s for the next several hours. Previous
discussion is below.
MRMS Radar imagery shows an area of showers with isolated
thunderstorms moving across western NY and northern NY at this
time. This area of showers and isolated thunderstorms was
associated with a west to southwest 50 knot low-level jet close
to 850 mb as per the SPC mesoanalysis. This low-level jet was
leading to decent moisture advection and isentropic lift which
in effect was supporting the precipitation. The winds will be
stronger farther north vs in northern PA and hence radar
returns show less precipitation farther south into northwest PA
and eastern OH. Overlaying the latest HRRR reflectivity with the
mosaic radar and MRMS radar imagery shows it has a decent
handle on the timing and areal coverage of the precipitation. So
we used the HRRR reflectivity fields to guide us in our hourly
POPs into this evening with this first warm advection wave.
Highest POPs will be across north central NY and lowest down
into northeast PA. We expect categorical POPS in NC NY down to
chance in northeast PA late this afternoon into the evening.
Once this feature passes by, fair skies and dry conditions will
prevail for the overnight.
&&
.SHORT TERM /SUNDAY NIGHT/...
For Sunday, models all show a strong zonal flow pattern with a
more southwesterly flow near the surface. Models show strong
shear as a short wave and attendant jet streak move across the
Great lakes region during the day. NY and PA are in the right
exit region of this straight jet flow pattern and hence there
isn`t as much upper level divergence as you would expect.
Additionally there isn`t much in the way of height falls. Model
instabilities are the big question which is typical this time of
year. The latest NAM approaches 1000 J/Kg, with the GFS between
300 and 500 J/KG mixed layer CAPEs. Helicities are not that
strong but the bulk shear between 0 and 6 Km approaches 50
knots. So if anything can get going we would expect line
segments and possible bow echoes with damaging winds the highest
threat. However, if CAPE is less than 500 J/kg and with weaker
forcing, this could be a non-event with the shear overwhelming
the weaker CAPE. SPC day 2 outlook has central NY and northeast
PA in general thunder. If CAPEs are a bit higher I wouldn`t be
surprised if our area is in at least a marginal risk. For now we
will keep mention in HWO for Sunday afternoon/evening.
For Sunday night, cold front exits the region and precipitation
follows it out of our area.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
High pressure will build in for the first part of the work week
bringing drying conditions and seasonably mild air. Dual upper
waves come at the area for Wednesday, with one coming through
the central lakes and the other more southern system coming out
of the Tennessee valley. This should bring another round of
showers and isolated thunderstorms into Thursday. Expect brief
drying Friday ahead of yet another system for the weekend.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
VFR weather is expected through much of this forecast period.
Main concern will be the decoupling of surface winds tonight
with a strong low level jet on the order of 35-45 knots
expected off the deck. This may introduce some areas of laminar
LLWS from 04Z-12Z. Winds will again be a concern during the day
Sunday as low level instability ahead of an approaching cold
front promotes a modest gust potential approaching 25-30 knots.
Models are suggesting potential for convective shower and
thunderstorm development during the afternoon. A little early to
explicitly include in the terminal forecast, but a weather
concern for flight ops to plan for. Timing for best activity
would be during the 18Z-23Z time frame.
Outlook...
Sunday night...Evening SHRA/TSRA ending with ceiling
restrictions possible through the night.
Monday...Lingering ceiling restrictions possible in the
morning.
Monday night - Tuesday...VFR.
Wednesday - Thursday...Possible restrictions in showers.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...DJN/TAC
NEAR TERM...DJN/MSE
SHORT TERM...DJN
LONG TERM...MLJ
AVIATION...JAB
Area Forecast Discussion
National Weather Service Bismarck ND
959 PM CDT Sat Apr 15 2017
.UPDATE...
Issued at 943 PM CDT Sat Apr 15 2017
Scattered rain showers continue across northwest and north central
North Dakota as of 0245 UTC, with a well defined circulation noted
across the north central within radar and GOES16 WV imagery.
Thus, increased PoPs downstream of this circulation over the next
few hours as this feature is not been resolved well by the 01 UTC
CAM suite.
UPDATE Issued at 652 PM CDT Sat Apr 15 2017
Diurnal convection across western and south central North Dakota
has begun to diminish over the past hour through 00 UTC. A more
sustained area of precipitation from around Steele through the
Turtle Mountains will continue via greater forcing associated
with the mid level shortwave. Expect any lightning potential with
this area of precipitation to wane quickly by 02 UTC.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 345 PM CDT Sat Apr 15 2017
The main concerns in the short term are the ongoing precipitation
chances this afternoon into tonight, followed by fire weather on
Sunday.
Late afternoon radar mosaic shows showers and isolated thunderstorms
moving across central North Dakota. Short term high resolution
models suggests this activity will continue to lift north and east
with the best chances lingering towards the Turtle Mountains
later this evening. Have trended towards the latest HRRR for the
hour by hour pops since it has generally grabbed onto the latest
trends.
The concern for Sunday will be fire weather with minimum relative
humidity values forecast to approach 20 percent in parts of the
south Sunday afternoon. Have increased winds a bit from forecast
guidance with NAM BUFR soundings suggesting good mixing and
sustained winds in the 20 to 25 mph range. This combination of
winds and minimum relative humidities could create near critical
fire weather conditions for Sunday afternoon. Did not hoist any
Fire Weather headlines for now, but it`s something that will have
to be monitored.
.LONG TERM...(Sunday night through Saturday)
Issued at 345 PM CDT Sat Apr 15 2017
The long term period will feature periodic chances of
precipitation with seasonable temperatures. The best chances
appear to be Monday night as a fairly strong H5 wave/low moves
across the central and northern plains. The model blend has gone
with likely (or higher) pops across the southern half of the
state Monday night which looks reasonable. Have carried rain as
the dominant precipitation type, though some snow could mix in,
especially at night and into the early mornings.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 943 PM CDT Sat Apr 15 2017
Scattered showers will continue across northwest and north central
North Dakota tonight. Expect VFR conditions outside of
precipitation. A breezy Sunday is forecast with westerly gusts of
25-35kts with VFR conditions.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...CK
LONG TERM...CK
AVIATION...AYD
Area Forecast Discussion
National Weather Service Caribou ME
1048 PM EDT Sat Apr 15 2017
.SYNOPSIS...
A warm front will lift across the area tonight bringing some
rain to the region. Low pressure will cross the region Sunday
with a cold front crossing the region Monday. This will bring
more rain into Sunday evening with possibly some wet snow to
the northern regions later Sunday night into Monday morning.
&&
.NEAR TERM /THROUGH SUNDAY/...
945 PM Update: The only chg was to lower ovrngt lows across the
NW based on latest obs which showed sfc temps already lower then
the prev fcst ovrngt lows due to a pd of mclr skies allowing for
some radiational cooling ovr this ptn of the Rgn. Temps should
become steady ovr this area and then begin to rise later tngt as
cld cvr from QB eclipses the region prior to sct shwrs and lgt
rnfl xpctd to arrive late tngt.
Orgnl Disc: Wet weather on the way for this term.
Clouds will be on the increase this evening as a warm front
lifts across the region. The RAP and NAM indicate that a weak
area of low pres will develop along the front as it moves ne.
There appears to be enough forcing and convergence to allow for
some rain develop overnight into Sunday morning. There appears
to be a split in the placement of the best rainfall as a batch
of 0.25 to 0.30 inches shows up across the northern 1/2 of the
CWA and another area across the downeast areas close to 0.25
inches. Temperatures will cooldown this evening especially
across the northern areas as some partial clearing will be
around early, but temps should level off later at night w/the
thickening clouds and rain. Overnight lows will be in the 40s
w/some of the far northern sites hitting the upper 30s. South
winds kicking in overnight will allow for some fog to develop
especially across the northern and central areas where some snow
still resides.
The first round of rain will end by mid morning Easter Sunday as
the low pushes into New Brunswick. As it does sow, the
associated cold front will slide across northern sections and
then stall across central Maine. This will set up a divide
w/much cooler air across the north and Springlike temps to the
s. Some drizzle and low clouds will hang around across the
northern areas while downeast areas could see breaks in the
clouds w/some sunshine. This will allow for temps in the region
to warm significantly hitting the upper 60s to around 70s while
northern areas stay in the upper 40s and lower 50s. The next
round of rain is slated to arrive later in the afternoon as
another low moves in from the west. The low is forecast to move
across central areas w/the bulk of the QPF expected across the
northern 1/2 of the CWA w/some areas seeing 0.50 to 0.75 inches
of rain. Further s across the Bangor and Bar Harbor region,
moisture and dynamics appear limited and therefore cut back on
pops to low chance(20%). Earlier runs of the guidance including
the NAM and GFS pointed to some possible convection, but the
latest 12z runs of the guidance have pulled back on this
potential. Some elevated instability is there, but w/the
dynamics limited, decided not to include any mention of tstms.
The later shifts can assess this potential.
On the Hydrology side, additional rainfall(QPF) and snowmelt
will lead to rises on the rivers. There is some snowmelt and ice
still to move out, but attm thinking here is that QPF is not
substantial enough to bring mainstem rivers to Flood Stage w/the
exception of Mattawamkeag River(MATM1)as it is in Flood attm
w/minor flooding. Plus, temps will be falling back on Monday
into Tuesday especially across the north. This being said,
things will still need to be monitored.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
Rain will be ongoing Sunday evening as low pressure crosses the
region. Model guidance can`t quite agree on the
timing/placement of this low, but overall trend is for a path
from roughly Moosehead Lake to Calais. This would place the
heaviest slug of rain across the northern half of our forecast
area. Some of the guidance is producing quite a bit of QPF, but
current thoughts are that the models are having a hard time
resolving earlier convection, so this QPF is overdone. Have gone
with a more conservative blend for now, with perhaps as much as
another quarter to a third of an inch overnight. Once the low
pulls to the east, cold air will follow in its wake. This will
allow rain to mix with snow across northern Maine, and likely
all snow over the Saint John Valley. Any accumulation would be
an inch or two, with the highest amounts across the Allagash
northward to Escourt Station. Can`t rule out a brief period of
sleet during the rain/snow transition, but if this were to
occur, it would be localized, so have not mentioned it in the
forecast.
The aforementioned precip will gradually lift northward and come to
an end Monday morning as the low pulls away. Temperatures look to
stay quite cold, especially over the Crown of Maine where highs will
struggle to reach 40. Further south, highs will be in the mid 40s to
lower 50s across the Central Highlands down to the Coast. High
pressure will build across the region Monday night, leading to dry
and cold conditions; lows will bottom out in the upper teens to
lower 20s in the north and around 30 south. Tuesday will see a mix
of sun and clouds with highs in the 40s areawide.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The pattern will remain active through much of next week with
precipitation expected every couple of days. High pressure will
linger across the region into Wednesday morning. Then the
chance for rain returns as low pressure and its associated
frontal boundary push across New England. High pressure resumes
by later Thursday through Friday, then another system makes a
run at us for the weekend. The precipitation should fall mainly
as rain for both the Wed- Thu and Sat events, with perhaps some
snow mixing in across the North Woods during the overnight
hours. Temperatures will be near normal for mid to late April.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: VFR to start things out this evening and then
conditions are expected to drop to MVFR and then IFR overnight
into Monday. Improvement to VFR is expected across KBGR and KBHB
by Sunday afternoon while northern terminals are expected to
remain IFR/MVFR.
SHORT TERM: IFR conditions will be likely at the northern
terminals 00z-12z Monday as low pressure brings rain and snow to
the region. BGR and BHB should remain MVFR in rain, though
occasional IFR cannot be ruled out. Conditions will improve from
south to north Monday, with all terminals to be VFR by 00z Tue.
VFR conditions will prevail thereafter as high pressure builds
over the region. The next chance for precipitation and lower
ceilings/visibility will arrive late Wed into Wed night.
&&
.MARINE...
NEAR TERM: SCA remains in place as is for now. Winds and seas
have been slow to come up this afternoon. Therefore, started
things out on the low end and then bring s winds up to 15 to 20
kt overnight w/seas building. Stayed close to the midnight
crews thinking of gust to 25+ kts and seas rising to 6-7 ft by
Sunday.
SHORT TERM: Low pressure will move by just to the north of
the waters Sunday night and Monday morning, followed by high
pressure through Tuesday. While winds are not expected to reach
25 kt, seas will likely remain at 4-6 feet through Monday.
Therefore, the current Small Craft Advisory will likely need to
be converted over to one for hazardous seas and extended another
24 hours or so. High pressure will keep conditions below SCA
levels Tuesday and Tuesday night, but another low pressure
system will approach Wednesday into Wednesday night, which would
serve to increase winds and seas.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory until 8 PM EDT Sunday for ANZ050>052.
&&
$$
Near Term...VJN
Short Term...Hastings
Long Term...Hastings
Aviation...VJN/Hastings
Marine...VJN/Hastings
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
955 PM CDT Sat Apr 15 2017
.DISCUSSION...
Area radars show a few showers and storms between the Rio Grande and
the Serranias del Burro to the Big Bend as well as from Sonora to
north of San Angelo. The ongoing slight chance POPs for the Hill
Country to the Rio Grande look good. This is based on a majority of
Hi-res models that generally indicate the ongoing activity and with
the expectation that the activity slowly wanes overnight with sunset
and loss of heating while the cap strengthens. Only change is to
extend POPs for the Rio Grande into the overnight. Temperatures,
dewpoints, and winds are very close to ongoing forecast and will only
retrend these sensible weather parameters for the remainder of
tonight into Easter Sunday morning. Models still show a potential of
one or more compact MCSs to move across South Central Texas Easter
Sunday afternoon through Monday night.
&&
.PREV DISCUSSION... /ISSUED 650 PM CDT Sat Apr 15 2017/
AVIATION... /00Z TAFS/
Isolated convection is shown in the TAF impact the DRT vcnty through
01Z as echoes have just appeared on radar over the Rio Grande. Hi-
res models depict additional activity later in the evening, but will
wait to see how they react to the brand new activity before
factoring into the TAFs. If the latest HRRR is on track, there could
be some late night propagation of showers into the San Antonio area
as well. The rest of the TAFS are the typical spring pattern of low
clouds forming in the late evening, dropping to ifr at daybreak, then
mixing to vfr levels by early afternoon.
PREV DISCUSSION... /ISSUED 331 PM CDT Sat Apr 15 2017/
SHORT TERM (Tonight through Sunday Night)...
Temperatures have warmed up into the upper 70s and lower 80s across
the region under partly to mostly cloudy skies. A weak shortwave that
helped trigger isolated showers and thunderstorms late this morning
across the Edwards Plateau dissipated as they moved east into strong
capping. Aircraft soundings out of AUS and SAT still show very
strong capping aloft which should continue to suppress convection
this afternoon aside from perhaps a few brief showers beneath the
cap. Hi-res and global models indicate that isolated to scattered
showers and thunderstorms will develop late this afternoon just over
the border in Mexico as a weak shortwave traverses the Serranias del
Burros, which appears on track as WV imagery shows a shortwave just
to the west of this range. There is greater uncertainty on whether or
not this activity will hold together into the Rio Grande Plains and
Edwards Plateau given a relatively strong cap aloft, but have
maintained 20 POPs in those areas for the evening hours when the cap
should be weakest. Some additional shower activity and possibly an
isolated thunderstorm may develop further northeast into the western
Hill Country late in the overnight hours into the morning with the
remnants of this wave, but confidence is lower for that forecast.
Rain chances appear to be slightly higher tomorrow across the region
as weak shortwave forcing and a weaker cap aloft allow for isolated
to possibly scattered showers and thunderstorms across the region.
However, it is hard to tell if the cap will weaken enough to allow
for this development and if so where exactly this will materialize.
Therefore, for now have blanketed the region with 20 POPs tomorrow
afternoon with high temperatures near where they are today with
perhaps a bit more cloud cover. More significant shortwave forcing is
expected to trigger strong to severe showers and thunderstorms along
a dryline in west Texas tomorrow afternoon, which some hi-res and
global models are showing will merge into an MCS downstream that
moves through the Edwards Plateau and Rio Grande Plains and possibly
further east Sunday night into Monday morning. Thus, 40-50 POPs
continue mainly east of Highway 281 and Interstate 35 tomorrow night.
LONG TERM (Monday through Saturday)...
Monday continues to look like the wettest day of the next week as the
strongest shortwave possibly develops a closed circulation as it
slowly moves east across the region. The Texas Tech WRF and ECMWF
both suggest this MCS may leave behind an MCV that may help reinforce
this mid-to-upper level disturbance and trigger even more widespread
shower and thunderstorm activity across the region. If this comes to
fruition, we may end up having a locally heavy rainfall threat, but
capping aloft for now and uncertainty in that solution favors just
scattered to widespread showers and thunderstorms. The greatest
coverage should be further south where dynamic forcing associated
with the upper level disturbance will most likely be greater and the
cap aloft will most likely be weaker. Although instability will be
high enough to support strong to marginally severe thunderstorms,
shear parameters are very weak so organization should be limited to
single cells with perhaps multicellular clusters. Rainfall amounts
should generally remain below one inch unless better organization or
an MCV materializes.
Rain chances will begin to decrease on Tuesday before ending for the
most part on Tuesday night as the shortwave disturbance moves east
of the region. A mid-to-upper level ridge will build in from the
southwest by Wednesday for the rest of the work week to cause
temperatures to increase into the mid 80s to lower 90s across the
region with significant capping aloft preventing any shower or
thunderstorm development. Global models consistently depict a
relatively strong front moving through the region late next week as
an upper level disturbance deepens and ejects over Oklahoma or
Kansas. Showers and thunderstorms are expected along this front, but
kept POPS below 40 percent for now in any one period given the more
progressive GFS solution brings this system through Friday evening
while the less progressive ECMWF holds off until Saturday morning.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 68 83 67 82 65 / 10 20 20 40 20
Austin Bergstrom Intl Airport 68 82 67 81 64 / 10 20 20 40 20
New Braunfels Muni Airport 68 82 67 81 64 / 10 20 20 50 20
Burnet Muni Airport 66 79 65 78 62 / 10 20 30 40 20
Del Rio Intl Airport 69 85 67 82 65 / 20 20 50 40 30
Georgetown Muni Airport 67 81 66 80 63 / - 20 20 40 20
Hondo Muni Airport 68 84 67 82 64 / 10 20 50 50 30
San Marcos Muni Airport 67 82 67 81 64 / 10 20 20 50 20
La Grange - Fayette Regional 69 83 68 82 65 / - 20 10 40 20
San Antonio Intl Airport 69 83 68 81 65 / 10 20 30 50 30
Stinson Muni Airport 69 83 68 81 65 / 10 20 30 50 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Oaks
Synoptic/Grids...04
Public Service/Data Collection...YB
Area Forecast Discussion
National Weather Service Gray ME
932 PM EDT Sat Apr 15 2017
.SYNOPSIS...
A warm front will cross the region tonight. A cold front will
approach from the northwest on Sunday and will drop south
through the region Sunday night. A trough of low pressure will
linger over the area on Monday. High pressure will build over
the region Monday night and will shift east on Tuesday.
Weakening low pressure will move in from the west on Wednesday
and will cross the area Wednesday night. High pressure will
build by to the north on Thursday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
930 pm Update: Made some adjustments to POPS based on latest
radar, then used HRRR going forward to 05z. Also lowered QPF
amounts some over central NH into western ME. Made some
adjustments to temps/dewpoints based on latest mesonet data.
630 pm Update: ESTF update to include latest mesonet data.
Forecast on track and no changes needed at this time.
Previous Discussion:
Warm front approaching from the west will spread clouds into the
region through the remainder of the afternoon with rain not far
behind. Expect showers to move into western zones by early
evening and this activity will overspread the remainder of the
forecast area through the evening hours. Should be a quick
hitter with precip ending in southwest zones shortly after
midnight and by daybreak across most of the forecast area.
Still looking for a quarter to a half inch of QPF with highest
amounts in the north....which should not cause any problems with
flooding on area rivers. Lows overnight will range from the mid
40s to lower 50s.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Sunday will feature mostly cloudy skies in the north with
occasional showers and some afternoon thunderstorms possible.
Farther south a mix of sun and clouds will allow temperatures to
rocket well above normal and may fire scattered afternoon
convection as the front drops south. The combination of rain and
snow melt will have to monitored closely as RFC once again
bringing area rivers to bankfull of slightly above flood stage.
Looking for highs in the 60s to lower 70s north and ranging
through the 70s to near 80 south.
Cold front will slowly drop south through the region Sunday
night with evening showers and thunderstorms gradually ending
in southern zones by midnight with partial clearing. Clouds
will hang tough in the mountains where scattered showers will
be possible through the night. Low temperatures overnight will
range through the 40s north and lower to mid 50s south.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
High Impact Weather Potential: Some wet snow possible over the
mountains and far northern portions of NH and western ME
Wednesday and Wednesday night.
Pattern: Rather progressive pattern evident when looking at the
northern hemisphere early this afternoon with unimpeded flow into
the Atlantic /+NAO/ allowing systems to traverse North America
rather rapidly. There is some degree of Rex blocking over the north
central Pacific /-EPO/ which suggests some impact of the northern
stream and associated Polar air...but the pattern also looks active
as shortwaves emanate from the "low" member of the Pacific
block...with these small scale features moving east rapidly
under potent mid/upper level flow. Thus...while the early
portion of the long term forecast appears quiet with shortwave
ridging building overhead...we/ll be looking towards two
shortwaves for our impactful weather this week...the first late
Wednesday - early Thursday and the second by Friday. Thus...a
relatively unsettled period is expected...with temperatures
rolling up and down between impulses...but overall a bit below
normal for this time of year.
Model trends/confidence: While the active pattern and overall setup
is agreed upon...there are fairly significant shortwave differences
by day 4 /Wed/ east of New England which lowers confidence beyond
this portion of the forecast period...with the rapidity of the flow
also adding a level of uncertainty.
The Details....
Monday - Monday Night: Cold front south of the region will continue
to pull away on Monday...with somewhat of an inverted trough
lingering over northern New England to start the day /at least
partially forced by continued morning +DPVA at mid levels/ with
cool/dry advection ongoing throughout the day. Expect lingering
moisture and forcing for ascent to allow for morning rain and snow
showers in the mountains...with drier conditions by afternoon. T8s
still +2-4C to start the day over southern areas dropping to or
below the freezing mark by Monday evening. This suggests
another warm day along the coastal plain with downsloping wind
component adding a few degree boost to temperatures. A few spots
over southeastern NH may make a run at 70 in this regime...with
60s widespread north to the foothills...but highs likely stuck
in the 40s north of the mountains. High pressure continues to
build into the region Monday night with at least partial
clearing and slackening winds allowing lows to fall back into
the 20s north and 30s south.
Tuesday - Tuesday Night: High pressure anchored north and east of
New England will dominate our weather for the Tuesday/Tuesday night
period with a seasonably cool/dry airmass in place. Placement of
high portends a cool southeasterly flow. There is some support
still in place /GFS/ for marine stratus...but this is not supported
by the ECMWF...with the dry character of the airmass likely limiting
this potential. 2M temperatures from the deterministic guidance
suggest a very chilly day...with 40s essentially everywhere. Will
trend temperatures a bit below the consensus given this signal.
Guidance consensus looks like a good start for Tuesday night
temperatures with top down saturation arrives on the heels of the
shortwave ridge axis. A clearer scenario might allow for a rather
chilly night...but too many potential spoilers for this to make big
changes to forecast temps.
Wednesday-Thursday: Next shortwave arrives on Wednesday with warm
advection associated precipitation arriving during the afternoon.
Trends have been for this system to be weaker as downstream cutoff
low allows shortwave ridge to it/s west to amplify...essentially
blocking/weakening the incoming wave. Still the weakening low will
have access to a 1" PWAT moisture plume with a good southerly llevel
jet. Antecedent temperatures aloft will be marginally cold enough
to bring ptype into play...with over one half of the EC-EPS
members supporting some snow in the mountains and far northern
Oxford/Franklin/Somerset counties. It/s a bit too early to get
into that much detail...but the setup does not support much in
the way of winter weather impacts. Marginal temperatures and a
weakening system will likely have no impact during the daylight
hours on Wednesday with any potential impact in these
northern/high terrain areas potentially occurring Wednesday
night...but warm advection regime suggests even this may be hard
to pull off. Will continue with RA/SN mix wording in these
areas. Gradual and brief improvement appears to come during the
day Thursday as remnants of low pull east of the region. Lots of
residual moisture suggest ample cloudiness...likely not
allowing us to fully mix out to T8s of +1-5C. This will keep
most if not all of the area in the 50s...with some 40s in the
mountains.
Friday - Saturday: Good agreement in another shortwave and
associated low pressure system arriving from the west...this time
moving north of the region...bringing another threat of rain to the
region for Friday. This track should preclude any ptype issues. Too
early to think about amounts...but important to watch with rivers
running high after recent rains/snowmelt. An early look at the start
of next weekend suggests seasonably cool and dry air pushing back
into the region.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Short Term...MVFR/IFR ceilings developing this evening.
VFR in the south on Sunday with areas of MVFR ceilings in the
north. VFR Sunday night in the south with areas of MVFR ceilings
in the north.
Long Term...VFR likely all terminals Monday through early
Wednesday. Rain arrives Wednesday with MVFR/IFR restrictions
likely Wednesday afternoon and Wednesday night with some
potential lingering MVFR conditions on Thursday. Next system
arrives Friday with another round of restrictions with
improvement likely by next weekend.
&&
.MARINE...
Short Term...Continuing SCA`s tonight into Sunday.
Long Term...Winds subsiding to start the period Monday with
SCAs likely coming down during the day. This will be followed by
quiet conditions through the first half of Wednesday.
Southeasterly winds ahead of arriving low pressure system may
necessitate SCAs /esp in the outer waters/ on Wednesday-
Thursday...with lingering northeasterly winds keeping seas near
SCA levels to end the week.
&&
.FIRE WEATHER...
Increasing RH and widespread beneficial rain tonight. Clearing
Sunday with very warm temperatures and RH only dropping as low
as the 30-40 percent range. Early to midweek a return to cooler
temperatures.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 5 PM EDT Sunday for ANZ150>154.
&&
$$
Area Forecast Discussion
National Weather Service Wichita KS
929 PM CDT Sat Apr 15 2017
.UPDATE...
Issued at 928 PM CDT Sat Apr 15 2017
Convection continues along a slow moving cold front, from KSLN to
KGBD. Training and back building storms and a few severe storms
continue in this area as low level jet continues to feed into this
area. Latest short term RAP model data shows low level jet and
moisture transport will begin to veer to the east-northeast towards
05-06z, which should lead to convection in Central KS waning some or
beginning to propagate more to the SE. So the heavy rainfall threat
will continue for a few more hours in Central KS. As this low level
jet veers to along the KS Turnpike, could see additional convection
develop after 06z ahead of the ongoing convection for portions of
the Flint Hills and across South Central KS (ie...Wichita Metro).
Current pops look on track, shifting the convection to the south-
southeast overnight. There is some concern that the back
building/training convection threat will shift into southern KS
overnight or early Sunday morning as moisture transport stays
focused from wrn OK into srn KS. The only caveat from this scenario
playing out, is how strong the cold pool from the Central KS storms
becomes, which could push the convective chances further south into
northern OK. Will have to keep an eye on this, but will stay the
course for now, as cold pool really hasn`t gotten going yet.
Ketcham
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 337 PM CDT Sat Apr 15 2017
Active weather pattern thunderstorm-wise expected to continue
through Friday-Saturday.
A cold front stretched from southeast Nebraska southwestward to a
developing triple point over southwest Kansas, with a dryline
extending south of the triple point into the eastern Texas
Panhandle. Very strong instability (MLCAPE 2500-3500 j/kg) and
30-35 kt of effective bulk shear will be in place near and
southeast of the front, where upper 50s to middle 60s dewpoints
exist in the warm sector. Strong heating and areas of frontal
convergence should allow widely scattered severe storms to develop
toward early this evening near the front. Large hail and damaging
wind gusts will be the main hazards this evening. Short-term
models also indicate forcing from the low-level jet and isentropic
lift may initiate scattered storms over the Flint Hills region
this evening which could also pose a hail/wind threat. The cold
front will shift slowly southward overnight into a 40-45 knot
southerly low-level jet, which will tend to veer just ahead of the
boundary late. This will likely support storms merging into
larger clusters, which may have some back-building tendency,
favoring locally heavy rainfall and localized flooding potential
in south-central/southeast KS late tonight.
Sunday-Sunday night...If overnight convection develops a fairly
substantial cold pool, thinking precipitation chances will be
fairly minimal Sunday morning across the forecast area, with
greater chances further south across Oklahoma, in vicinity of the
convectively-reinforced frontal zone. However, thinking
shower/storm chances will increase late afternoon into Sunday
night, as the NAM/GFS approach a subtle upper wave from the
southwest, inducing warm/moist advection atop the frontal zone.
Limited instability should preclude widespread severe weather.
Monday-early Tuesday...A 2nd weak upper wave is expected to
approach from the west, possibly supporting isolated hit-or-miss
showers/storms Monday afternoon/evening, especially over southern
Kansas in vicinity of weak frontal zone washing back north. This
activity could linger into the nighttime hours in response to an
increasing low-level jet. Furthermore, could see additional
isolated activity Monday night into early Tuesday further north
across central into east-central Kansas, as a Northern Plains
shortwave advances a cold front into Mid-America. However, suspect
better chances will remain north of the region near better
forcing.
Tuesday afternoon-night...Could see a few storms develop along a
weakening cold front from central into northeast Kansas. If this
occurs, strong instability with marginal deep layer shear would
support a few severe storms. Activity could fester and/or develop
through the overnight across central/northern Kansas as a
strengthening low-level jet impinges on the west-east oriented
frontal zone, with a continued threat for strong/severe storms and
heavy rain.
.LONG TERM...(Wednesday through Saturday)
Issued at 337 PM CDT Sat Apr 15 2017
Wednesday afternoon-night...GFS and ECMWF overall synoptic
pattern continue to suggest the potential for somewhat more
widespread and/or higher end severe weather, as a vigorous
shortwave and associated cold front approaches from the west,
interacting with an increasingly moist/unstable airmass in place
across the Heartland. What especially gets our attention is the
increasing mid-upper level flow and associated deep layer shear.
Details remain sketchy this far out, so check back for later
forecasts.
Friday-Saturday...Attention then turns to a powerful storm system
expected to approach the Central/Southern Plains late week into
the weekend. Despite fairly substantial spread amongst individual
GFS ensemble members, overall medium range consensus continues to
support the synoptic pattern surrounding this storm system. That
said, thinking greatest severe weather potential will remain south
of the Kansas region closer to the warm sector, with a greater
potential for widespread rain/embedded storms across Kansas, along
with much cooler temperatures (highs possibly in the 40s-50s and
windy Fri-Sat). However, still quite a bit of uncertainty this far
out, so will continue to monitor model trends.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 633 PM CDT Sat Apr 15 2017
Widely scattered storms are expected to develop along a slow,
southward moving cold front across central Kansas within the next
hour or two. Will include a VCTS mention at RSL/GBD/SLN/HUT to
account for this convection potential, with prevailing shra/VCTS
from 01-05z. Other clusters of strong-severe storms should develop
over eastern Kansas in the mid evening time period, with a
strengthening low-level jet with increased moisture transport. T
The front will continue to push south into south-central/southeast
KS overnight, into a 40 knot southerly low-level jet, including some
potential for storm clusters to back-build across south-
central/southeast KS. Some MVFR ceilings may develop along and just
north of the cold front during the morning hours Sunday.
Ketcham
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 58 66 56 73 / 60 50 50 20
Hutchinson 55 64 53 72 / 70 50 30 20
Newton 56 65 54 71 / 50 50 40 20
ElDorado 58 67 56 72 / 70 50 50 30
Winfield-KWLD 59 68 58 74 / 70 50 50 30
Russell 49 64 50 72 / 20 20 10 10
Great Bend 50 63 50 72 / 50 30 20 20
Salina 54 65 52 73 / 60 20 20 20
McPherson 54 65 52 72 / 70 40 30 20
Coffeyville 61 69 59 74 / 70 60 60 40
Chanute 60 67 57 72 / 70 50 60 40
Iola 60 67 56 72 / 70 50 60 40
Parsons-KPPF 61 68 58 73 / 70 50 60 40
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Ketcham
SHORT TERM...JMC/ADK
LONG TERM...ADK
AVIATION...Ketcham
Area Forecast Discussion
National Weather Service Lincoln IL
914 PM CDT Sat Apr 15 2017
.UPDATE...
Issued at 910 PM CDT Sat Apr 15 2017
The 00z KILX sounding showed a relatively dry airmass still exists
across central IL, which will work to slow down the arrival of
showers and storms into our forecast area. The latest HRRR and RAP
are indicating that storms will reach NW Knox county around
midnight, then advance eastward the rest of the night ahead of the
cold front. Instability parameters show a weakening trend during
the time the convection progresses east of the Illinois river. We
could still see a few storms produce some strong winds to 50 mph
and hail up to an inch between midnight and 1 am up to the
Illinois river, but intensity of storms should diminish with time
the rest of the night. Have slowed down the arrival and
progression of storms in the grids to reflect the expected
trends.
The cold front will push across central IL tomorrow morning, so
overnight lows will remain very mild, in the low to mid 60s, with
the help of increasing clouds and steady southerly winds.
Conditions look to improve through the morning tomorrow from west
to east, with sunshine developing through the day, especially
north of a line from Springfield to Danville.
Updated forecast info is already available.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 314 PM CDT Sat Apr 15 2017
Elongated trof of low pressure stretching from the Upper Midwest
down into the Southern Plains this afternoon on the weather map. The
cold front along that trof is making slow progress towards the
region, and is expected to drive the weather through the overnight
hours. A very warm and windy airmass will lose ground to the
advancing front later tonight. The same mixing that provided the
gusts today also helped to dry out the dwpts at the sfc somewhat,
limiting the available moisture from the richer 60F dewpoints from
yesterday afternoon. Showers and thunderstorms along the boundary
tonight will have a limited opportunity to produce some severe
weather as the timing of the boundary is not ideal with daytime
heating. Remnant instability after sunset will likely keep the
severe mentions to a minimum overall, although an isolated hail or
wind report cannot be ruled out. Wind in particular may end up
translating down with some of the rainfall from just off the surface
as the low level jet increases later tonight. SPC has a marginal
risk west of I-55 in Central Illinois, with the better chances for
severe weather further back into the unstable airmass to the NW.
Precipitation should be ending slowly in the morning hours west of I-
55 and the remainder of Central and Southeastern Illinois will
likely take most of midday to clear from the lingering showers and
thunderstorms. Temperatures to the north will be in the lower
70s...and the precip will prevent too much early warming in the
south, limiting the daytime MaxT to the mid 70s.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 314 PM CDT Sat Apr 15 2017
Tomorrow night and through Monday will be slightly cooler in
the wake of the front, with highs on Monday only reaching into the
lower 70s with weak easterly flow at the sfc. The brief dry pd will
end quickly as the next surface low moves quickly across the Great
Lakes Tuesday afternoon, dragging a cold front through Central IL.
However, winds will veer to more southerly ahead of it...with
Tuesdays highs climbing up to the mid to upper 70s before the rain
moves in that afternoon/evening. Boundary lingers in parallel flow
aloft and the models are having a tough time discriminating
individual times for showers, resulting in a rain heavy forecast in
the med/longer range forecast. By the end of the week, a larger
system is expected to dig into the northern tier of the CONUS,
dropping temps to potentially below normal temps for the weekend.
Until then, forecast continues to run slightly above normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 715 PM CDT Sat Apr 15 2017
Storms have developed across eastern Iowa, in an axis of higher
instability ahead of the advancing cold front. The HRRR, RAP and
NAM-Nest all show a slow eastward movement of the line of storms
will be on the slow side, with storms finally reaching near PIA
around 07z. The storms should have a weakening trend as they
progress eastward of the Illinois river, but some isolated thunder
could still affect BMI, SPI, DEC and CMI between 08z and 12z.
Cloud trends look to lower to IFR tomorrow morning after the cold
front pushes through central IL. However, the low clouds should
dissipate in favor of VFR clouds by afternoon tomorrow.
Winds will remain gusty this evening from the south at 15g28kt.
Bufkit analysis shows a 45KT LLJ will progress across central IL
late this evening and overnight ahead of the cold front, creating
LLWS conditions at 2000 feet, 22045KT. The LLJ will weaken late
tonight, removing the threat of LLWS.
Winds will shift to the west early tomorrow morning, then to the
northwest by midday tomorrow.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Indianapolis IN
1151 PM EDT Sat Apr 15 2017
.UPDATE...
The AVIATION Section has been updated below.
&&
.SYNOPSIS...
Issued at 255 PM EDT Sat Apr 15 2017
A cold front will slide southeast across central Indiana on Sunday.
It will then stall across the Tennessee Valley on Monday. The front
will return as a warm front and move over the area on Tuesday. Then,
another cold front will stall over the area during the the middle of
next week before it moves through late next week as a surface wave
moves up along it. Finally, another frontal system is expected to
impact central Indiana next weekend. The end result will be periodic
showers and thunderstorms.
Warm temperatures are expected through next Thursday. Meanwhile,
next weekend looks a little cooler.
&&
.NEAR TERM /Tonight/...
Issued at 928 PM EDT Sat Apr 15 2017
Surface analysis this evening shows a progressive SW flow in place
across central Indiana. A strong cold front was in place from
central Wisconsin across Iowa to Central Kansas. Non-operational
GOESR satellite data shows thunderstorms along and ahead of the
front. Diurnal cu across Indiana was continuing to
dissipate..leading to clearing skies.
HRRR continue to suggest the progression of the storms upstream
pushing into Central Indiana after 09z-12Z. Ongoing forecast
handles this well and continued the trend of ramping pops upward
toward 09Z and beyond. Given the expected ongoing warm air
advection and good mixing...will continue to trend lows warmer
than MAVMOS.
&&
.SHORT TERM /Sunday through Tuesday/...
Issued at 255 PM EDT Sat Apr 15 2017
Main focus for the short term will be on timing and coverage of
thunderstorms, especially Sunday and Sunday night as a cold front
drops southeast over central Indiana and then the Ohio River.
Models suggest the aforementioned cold front will drop southeast
across central Indiana Sunday afternoon. Deep moisture and
instability, courtesy of a low level ahead of the front, will
interact with the frontal forcing and result in widespread showers
and thunderstorms Sunday, especially during the afternoon. Areas
south of a Elwood to Lebanon to Rockville line could see a few
strong or possibly even severe storms during the afternoon and
evening per the Day2 SPC Marginal Risk. With the front moving
gradually away, areas northwest of Indianapolis should see dry
weather Sunday night, while areas southeast of Indianapolis should
see some lingering activity. By 12z Monday, all but possibly extreme
southwestern parts of the area should see dry weather and partly
cloudy skies through Tuesday morning. However, models agree the
front will return northeastward as a warm front on Tuesday. This
could bring a few more showers and storms to central Indiana by
Tuesday afternoon.
Low level thickness progs and expected cloud cover support warm
blend temperatures with afternoon highs mostly in the 70s and
overnight lows around 50.
&&
.LONG TERM /Tuesday Night through Saturday/...
Issued at 205 PM EDT Sat Apr 15 2017
Model guidance depicts an active period with multiple disturbances
moving across the country along a fluctuating baroclinic zone across
much of CONUS. Model blend initialized with pops basically every
period, which is almost certainly way overdone, but pinning down any
one period to be dry is a difficult task. Will generally adhere to
regional initialization, but with the caveat that all day washouts
do not appear likely.
&&
.AVIATION /Discussion for the 160600Z TAFS/...
Issued at 1151 PM EDT Sat Apr 15 2017
VFR Conditions for the next several hours are expected to
deteriorate toward MVFR after sunrise Sunday morning.
Mostly clear skies were found across the area. Progressive SW
flow due to good pressure gradient will persist
overnight...keeping wind speeds up. HRRR suggests precip with the
approaching cold front and associated MVFR Conditions should be
reaching Central Indiana near 10Z-12Z. Time Heights suggest very
good lower and mid level moisture associated with the front
arrival and passage through mid afternoon on Sunday. Precip should
end by 22Z-00Z at all taf sites...except perhaps BMG as
progression southward may be slowed with this stalling front. At
that point a return to VFR conditions amid weak subsidence in the
wake of the front.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MK
NEAR TERM...Puma
SHORT TERM...MK
LONG TERM...NIELD
AVIATION...JP
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
1037 PM CDT Sat Apr 15 2017
.UPDATE...
Issued at 1034 PM CDT Sat Apr 15 2017
Grids have been updated to reflect a slower southeastward
progression of the front and associated SHRA/TSRA during the
overnight hours and into Sunday. A slower movement of the front
means that redevelopment of SHRA/TSRA on Sunday afternoon should
occur farther north and west than previously anticipated.
Kanofsky
&&
.SHORT TERM... (Through Late Sunday Afternoon)
Issued at 328 PM CDT Sat Apr 15 2017
Cold front over eastern Nebraska/western Iowa will move southeast
into Missouri tonight and continue to drift southward to stall
across southern Missouri Sunday. Developing showers and
thunderstorms over Iowa should grow upscale into an MCS tonight.
Storms will move southeast ahead of the front tonight and should
reach northwestern portions of our CWFA by 04-05Z. Latest RAP runs
show dwindling instability in our area as the line of storms
progresses southeast with MUCAPE falling below 1000 J/Kg between 06-
09Z. Additionally, the southwest end of the MCS over Oklahoma and
southwest Missouri will likely disrupt the low level jet further
northeast over our area and suck up much of the available
instability which should further weaken storms over our area.
Convection allowing models show this trend as well with a broken
line of weakening storms pushing through the southern 2/3 of the
CWFA from about 09Z through 15Z. Scattered showers and
thunderstorms will likely linger through the day on Sunday across
the eastern Ozarks...possibly becoming more numerous and invigorated
during the afternoon. Temperatures through the period will be
highly influenced by the precipitation...but we`ve been running warm
so I leaned a little closer to the warmer MAV guidance.
Carney
.LONG TERM... (Sunday Night through Next Saturday)
Issued at 328 PM CDT Sat Apr 15 2017
The chance of showers and thunderstorms will continue ahead of the
cold front on Sunday evening across southern Illinois and southeast
Missouri. The front will stall by midnight near the Missouri/
Arkansas border into the Ohio River valley. After midnight, low
level moisture convergence will set up north of the front over
central and southeast Missouri north of the front in response to low
level jet. This will result in showers and thunderstorms developing
late in the night, with the NAM depicting a MCS moving into
southeast Missouri and southern Illinois by Monday morning. The
chance of showers and thunderstorms will continue close to the front
on Monday afternoon over southeast Missouri and southern Illinois.
Active weather pattern will continue through next week as the
GFS/ECMWF/Canadian are in fairly good agreement that two shortwave
troughs and attendant cold fronts will move across the area on
Tuesday and Thursday. This will keep a chance of showers and
thunderstorms in the forecast for both of these days. There are
increased discrepancies by next Saturday when when the operational
GFS is faster with lifting a large upper low into the Midwest
compared to the ECMWF and Canadian which are slower. These slower
models are supported by the GFS ensemble mean, so have favored their
solutions with this forecast.
850mb temperatures will stay in the 10-15C range Monday into
Thursday before they cool behind a cold front. This will cause
temperatures to stay up above normal with highs in the 70s to around
80. Temperatures will fall closer to normal by next weekend as the
cold front moves south of the region behind Thursday`s cold front.
Britt
&&
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 657 PM CDT Sat Apr 15 2017
SHRA/TSRA have developed in Iowa early this evening along a cold
front. As the cold front sinks southward into MO/IL, SHRA/TSRA are
expected to congeal into a line and move through the terminals.
The expected timing as of TAF issuance is around 04z at KUIN,
around 07z at KCOU, and around 08z at KSTL/KSUS/KCPS. Expect a
period of MVFR conditions during SHRA/TSRA due to reduced
visibility in moderate precipitation as well as a period of MVFR
conditions after precipitation has ended due to lower cloud bases.
Winds will become northwesterly to northerly after FROPA.
Additional SHRA/TSRA are expected near the front after 18z, but
the front will probably be southeast of the terminals by that
time.
Kanofsky
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion...UPDATED
National Weather Service Miami FL
1035 PM EDT Sat Apr 15 2017
.UPDATE...
As of 1035 PM EDT...Quick forecast update to better account for
ongoing light showers reaching into portions of the interior. Have
updated PoPs to better reflect current radar and mesoscale
guidance through the remainder of the night, with most areas
seeing the potential for brief passing showers, generally light in
nature. Also updated sky cover to better reflect current
conditions, with partly to mostly cloudy skies expected through
the remainder of the night as moisture continues to stream in off
the Atlantic. It will continue to remain breezy as well,
especially along the east coast, with sustained winds 15-20 mph
with gusts 25-30 mph.
&&
.PREV DISCUSSION... /issued 803 PM EDT Sat Apr 15 2017/
UPDATE...
Surface analysis continues to indicate a strong 1030 mb surface
high centered halfway between New England and Bermuda. Clockwise
flow around this feature will maintain moderate easterly winds,
sustained 10 to 15 mph, across South Florida this evening into
tonight, especially along the east coast metro region. NWS radar
loop shows bands of showers streaming onshore from the Atlantic,
currently affecting portions of northern Broward and Southern Palm
Beach Counties. Short term models, including the HRRR and Hi- Res
WRF prog hit and miss showers to continue through the rest of the
night. With the update, increased coverage of PoPs over inland
Broward County to the account for the westward moving showers.
Otherwise, all other forecast variables appeared on track.
PREV DISCUSSION... /issued 428 PM EDT Sat Apr 15 2017/
DISCUSSION...
Through Sunday night: Latest surface analysis indicates a strong 1030
mb surface high positioned over the western Atlantic Basin, a few
hundred miles to the southeast of its position 24-hour prior.
The high has produced tight surface pressure gradients over south
Florida, residing on the southern extent of the feature. In
response, easterly winds have been breezy today, especially along
the east coast metro region, where gusts 25 to 30 mph have been
common. The easterly flow pattern continues to advect low level
moisture from the Atlantic over the peninsula, generating sporadic
lines of mainly light showers. However, not expecting much in the
way of accumulation with this activity, as PW around an inch is
rather unimpressive. This onshore pattern for the east coast will
help keep temperatures moderated, only topping out around 80
degrees. Further west in the interior, as the air drys and warms on
its journey over land, maximum temperatures will rise to the mid 80s.
Through Sunday, both the GFS and ECMWF prog the aforementioned high
to elongate, weaken slightly, and edge southeast towards Bermuda. In
response, breezy easterly winds will continue, through slightly
weaker than today. The strongest winds will occur along the east
coast metro region this evening, dwindling over the interior as
night approaches and atmosphere becomes less mixed. Over the next 36-
hours, short range models continue the hit and miss light showers
over the eastern portion of the peninsula. With marginal
instability parameters, thunder is not anticipated.
Monday through early next weekend: As high pressure begins to
settle over Bermuda, flow will shift to the east southeast over
South Florida. This pattern will slowly begin to advect in deeper
moisture, leading to an increase of showers and a slight chance of
thunderstorms. Southeast flow typically favors portions of the
western interior for afternoon convection. The 12Z GFS seems to me
more aggressive with bringing the deeper moisture over our
region, while the ECMWF keeps the moisture further south towards
Cuba. Either way, expect chances precipitation to increase
slightly, especially by mid week. If current guidance plays out as
expected, there will be an other increase in moisture and precip
by next weekend, ahead of an approaching cold front. Maximum
temperatures through the period will be in the low to mid 80s and
lows in the upper 60s/low 70s, which is around average for this
time of year.
MARINE...
Small Craft Advisory in effect for the Atlantic waters, including
Biscayne Bay through early Sunday morning...
Strong surface high pressure to the north will maintain breezy
east winds over the coastal waters through tonight. Waves 4 to 7
feet will be common for the Atlantic waters with rough seas.
Conditions improve slightly Sunday through early next week.
However, persistent east winds around 15 KT and seas 3 to 4 feet
will continue through the period. There will be a slight chance of
showers over the coastal waters, but thunderstorms are not
anticipated until mid to late next week.
AVIATION...
For the remainder of the afternoon, mostly SCT with some BKN
clouds between 035-070 will prevail at all South FL terminals as
gusty E winds continue. Only a few isolated showers may
potentially affect east coast terminals, not enough to warrant
VCSH in TAFs. Overnight, winds will decrease to 10-13 kts. East
winds will increase again around 14Z tomorrow.
BEACH FORECAST...
A High Risk of rip currents will continue for the Atlantic beaches
through at least Sunday with brisk onshore flow. An elevated risk of
rip currents looks to remain in place for the Atlantic beaches well
into next week as well.
FIRE WEATHER...
Strong high pressure to the north will maintain breezy early winds
into this evening. Easterly flow is expected to continue through
early to mid next week, strongest during the afternoons, then
weakening during the nights. RH values may approach critical levels
in the afternoons the next several days, but only for a few hours.
Otherwise, there will be a slight chance of showers through early
next week with chances increasing by mid week in a moist southeast
flow.
While no fire weather headlines are anticipated at this time,
fire weather interests should continue to remain alert of the
latest forecasts over the next several days, especially in
vicinity of ongoing wildfires.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 71 82 70 82 / 20 10 10 20
Fort Lauderdale 73 81 73 81 / 20 20 20 30
Miami 72 82 72 82 / 20 20 20 30
Naples 65 85 66 85 / 20 20 10 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Sunday evening for FLZ168-172-173.
AM...Small Craft Advisory until 8 AM EDT Sunday for AMZ630-650-651-
670-671.
GM...None.
&&
UPDATE...92/IRL
DISCUSSION...27/JT
MARINE...27/JT
AVIATION...88/ALM
BEACH FORECAST...27/JT
FIRE WEATHER...27/JT
Area Forecast Discussion
National Weather Service Norman OK
615 PM CDT Sat Apr 15 2017
.AVIATION...
Kept a mention of some VCTS at both GAG/WWR this evening. Expect a
period late tonight of lower MVFR ceilings at all sites. Also
possible that a complex of storms moves back south into northern OK
late tonight which may impact PNC. Have also added a mention of
thunder tomorrow afternoon at most sites.
30
&&
.PREV DISCUSSION... /ISSUED 223 PM CDT Sat Apr 15 2017/
.DISCUSSION...
Severe thunderstorm and heavy rainfall potential late this
afternoon through Monday night are the main concerns.
Through 10 pm tonight, will monitor for possible isolated to
scattered severe thunderstorm development near a dryline in far
western Oklahoma and far western north Texas as well as near a
developing triple point intersecting the dryline with a cold
front somewhere near Harper or Beaver county Oklahoma. Capping
will remain fairly strong and should limit storm coverage through
early tonight. Think the greatest chances for storm development
will be closer to the triple point where capping should be
weakest (cooler 700 mb temperatures +7 or +8C). First storm
development 5-7 pm seems possible near the triple point,
especially based on latest HRRR runs. Sufficient shear (0-6 km
bulk shear 30-40 kt) and instability (MLCAPE 2000-3000 J/kg)
support supercells with very large hail (greater than golf ball
size) as the main hazard if storms form. Increasing low level wind
shear (0-1 km bulk shear increasing to 20-30 kt by 8 pm) along
with LCLs 2500-4500 ft AGL support also a low tornado risk with
storms as well. Locally heavy rainfall could be possible (with
precipitable water values near 1" which is around the 90th
percentile for this time of year) as well as any storms should
move fairly slow 10-15 kt.
After 10 pm tonight, any supercells could grow upscale into a
complex/MCS as they move east/southeast with an increasing low
level jet, though confidence is low. A greater chance for a
complex/line of storms appears to form will be over southern
Kansas, closer to a cold front. These storms are forecast to move
south/southeast throughout the night into northern Oklahoma.
Severe potential is expected to slowly decrease as storms progress
south and east later tonight, though heavy rainfall potential
could increase. Kept the highest rain chances up towards
Ponca City.
Sunday and Sunday night, additional showers and thunderstorms
will be over the area as the cap should be weaker compared to
today, though pinpointing exactly where and when rain occurs
remains very difficult. The best guess is that most rainfall
during the morning hours will occur near and east of I-35 while
areas west may have the greater rain chances during the afternoon.
Do not expect all day rains any in one given area on Sunday. Some
severe thunderstorms with large hail and damaging winds mainly
during the late afternoon and evening hours will be possible due
to sufficient instability and shear. Heavy rainfall may become a
bigger concern due to abundant available moisture (surface
dewpoints in the 60s/above the 90th percentile for this time of
year) as well as slow storm motions (generally under 20 kt). One
or more pronounced surface boundaries will likely be somewhere in
Oklahoma which could enhance low level wind shear values.
Monday and Monday night, kept chances for showers and storms.
Locally heavy rainfall may be the main concern during this time
frame. Like Sunday, not all areas will receive rainfall. Weaker
wind shear should allow for lower chance for severe thunderstorms.
Tuesday through early Wednesday, stronger capping and slightly
drier mid/upper level air moving in should limit rain chances.
Late Wednesday into Thursday, rain chances may increase as a weak
front moves into the area, though confidence is low. Increasing
wind shear and some instability may support some strong storms
with locally heavy rainfall during this time frame.
Thursday night through Saturday, additional active weather appears
likely as moisture and lift increases ahead of a stronger
mid/upper level system. Heavy rainfall and/or severe thunderstorms
may be possible. Exact impacts and temperatures remain uncertain
as a surface boundary may be nearby. Regardless, wetter than
average conditions appear likely.
MBS
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 63 75 60 77 / 30 40 40 40
Hobart OK 62 77 58 77 / 20 40 50 30
Wichita Falls TX 64 80 60 80 / 10 40 40 30
Gage OK 58 71 53 77 / 40 30 50 30
Ponca City OK 58 73 58 75 / 60 60 50 40
Durant OK 64 77 62 79 / 10 30 30 40
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
10/17