Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/27/17
Area Forecast Discussion
National Weather Service Binghamton NY
833 PM EDT Fri May 26 2017
.SYNOPSIS...
Scattered light showers will persist this evening across central
New York before ending around midnight. Areas of fog are likely
to form across the higher terrain overnight. A weak storm
system will move across Pennsylvania on Saturday with a chance
for showers primarily over northeast Pennsylvania. A brief break
in the weather will occur on Sunday, however the next system
will move right back in and the chance for rain will exist
through the remainder of the week.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
830 PM Update...
Scattered showers continue within a cool, northwest flow and
weak upward motion around the western periphery of closed low
over New England coastal waters. Latest HRRR and NMM models
suggest consolidating a small band of isolated-scattered showers
across the Finger Lakes and I-81 corridor, extending a little
bit into the NEPA counties from not through midnight. Radar
trends seem to be in agreement at this time, so made some PoP/Wx
changes to reflect this thinking. We do expect some drier air
to work in overnight with diminishing instability and lift for
most of this spotty rain to end late. Will monitor the MCS
remnants over Lake Michigan, but for now the latest mesoscale
models also indicate the northern periphery of this feature
diminishes with showers passing mainly to our south early on
Saturday. Temperature/dewpoint/wind/sky trends still seem on
target for the rest of tonight.
Previous discussion...
By Sat afternoon the mid-lvl ridge will have shifted eastward
across the midwest and weak WAA will occur. 850MB temps will
rise to around 8.5 deg C, thus sfc temps will climb slightly
into the uppr 60-low 70s (north) across much of the area.
Anticyclonic flow aloft will continue Saturday night and high
pressure at the sfc will build across NY and PA. This will result in
Sat night being dry. Sfc temps will fall into the low 50s by Sunrise
on Sunday.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
Sunday...Current trends with latest model runs indicate the
upper level ridge will remain over the region late enough on
Sunday for a dry day for most if not the entire forecast area.
Will now advertise a dry morning with just slight chance/chance
pops in the Finger Lakes region, central southern tier and
parts of northeast Pennsylvania. Highs will range in the lower
to middle 70s under partly sunny skies.
Sunday night/Monday...Vertically stacked system will be situated
over Lake Superior while a secondary surface low in the central
Great Lakes region will track northeast into southern Ontario.
Mid level short wave and approaching warm front/surface trof
will bring increasing lift and moisture Sunday night with pops
increasing into the likely category. Best chance for rain
Sunday evening will be in the northern forecast area in the
vicinity of warm frontal boundary. By late night/early mornirng
surface trough will cross the area increasing the chance for
rain northeast Pennsylvania. By midday Monday this surface
boundary will be east of region and forcing will wane. Will
continue with likely pops Monday mornirng from I81 east then
chance for the afternoon. Due to mid level instability will
keep mention of a slight chance for thunderstorms both periods.
Highs Monday will range in the upper 60s to lower 70s.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Extended forecast continues to look showery as an upper level
low remains over eastern Canada. Will continue with chance pops
for showers through Thursday night with the highest probabilities
during the daytime due to increased coverage with diurnal
instability. By Friday conditions may be dry as upper level
heights rise and surface high pressure builds south from
Canada. Temperatures through the period will be near seasonal
normals.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Widespread restrictions are anticipated overnight, then through
14-15z Saturday, owing mainly to low ceilings and mist. At KBGM
and KITH, IFR-below alternate minimum restrictions are expected,
while KSYR, KRME, KELM, and KAVP range mainly in the fuel
alternate and MVFR categories.
From about 15z onward Saturday, an improvement to VFR is
anticipated, as the lower clouds scour out.
Surface winds will be light (5 kt or less) throughout the
period.
Outlook...
Saturday night through Sunday...Mainly VFR.
Monday through Wednesday...Restrictions possible from scattered
showers and perhaps thunder.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...JAB/KAH
NEAR TERM...JAB/KAH
SHORT TERM...RRM
LONG TERM...RRM
AVIATION...KAH/MLJ
Area Forecast Discussion
National Weather Service Duluth MN
733 PM CDT Fri May 26 2017
.UPDATE...
Issued at 722 PM CDT Fri May 26 2017
Have updated the forecast for the latest radar trends, as storms
are maintaining longer but are weaker than they were earlier this
afternoon.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 354 PM CDT Fri May 26 2017
A surface trof of low pressure was moving into St.Louis county
southwest through Aitkin county at 1920Z. A line of showers and
isolated thunderstorms were occurring along an ahead of this trof.
Followed the 17Z HRRR for timing of this activity through the
forecast area. The HRRR has been doing a reasonable job with this
activity for the last couple of runs. Storms should extend from Ely
to the Twin Ports to Pine City by 22Z/5pm, the Arrowhead to the
Hayward Lakes by 01Z/8pm, and come to an end by 03Z/10pm. The
surface trof will have moved east of the region shortly thereafter,
and with the loss of diurnal heating, no additional precipitation is
expected. After 06Z, look for fog to develop over the eastern two
thirds of the area with light winds and a clearing sky. The fog
should erode by 9am Saturday.
The forecast area will enjoy a break from the rain for most of the
day Saturday. By afternoon, showers are expected to develop in
response to a long wave trof that is progged to be found from
northeast Minnesota southwestward to eastern South Dakota by 00Z
Sunday. The showers will be found primarily from the Borderland
southwest to northern Cass county, with isolated thunderstorms
possible in the late afternoon. Max temps will be in the 60s near
Lake Superior, to the lower 70s inland.
.LONG TERM...(Saturday night through Friday)
Issued at 354 PM CDT Fri May 26 2017
A cutoff upper low will keep partly cloudy skies and occasional rain
chances in the picture Saturday night through midweek.
Scattered showers and isolated thunderstorms should be ongoing in
our western zones Saturday evening associated with an approaching
cool front. Showers will weaken overnight with another round of
showers and storms expected on Sunday. A few strong storms are
possible as NAM/GFS/GEM profiles indicate 1-1.5 kJ/kg of MUCAPE
during the afternoon. The strongest signal for potent thunderstorms
is over northwest Wisconsin, but portions of the Arrowhead may also
see a few strong storms. Most of the deterministic guidance features
a compact and relatively strong vort max and shortwave trough moving
through the Northland Sunday afternoon and evening. The GFS seems to
carry the best signal for strong storms with the vort max rotating
through the area during the late morning through mid-afternoon
timeframe. The GEM is similar, but a little slower and a few miles
farther north while the NAM and ECMWF has a much less defined
feature in the vicinity.
The closed low will wobble southeastward toward northern Lake
Superior Sunday night and Monday. Several vorticity maxima will move
across Minnesota and Wisconsin, and along with continued cold air
advection aloft, should support numerous showers Monday, and a
chance of isolated thunderstorms. A chance of scattered showers will
continue off and on through Wednesday night as the closed low
continues drifting toward New England and gradually fills. High
pressure returns Wednesday night into the weekend.
Temperatures will be near to slightly above normal with highs in the
upper 60s and low 70s and overnight lows in the 40s and upper 30s. A
lake breeze will be present some afternoons limiting temperatures
near Lake Superior.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 722 PM CDT Fri May 26 2017
Initial band of showers and thunderstorms only affecting KHYR
until approximately 02z this evening, then moving east and leaving
all the terminals dry through the remainder of the TAF period. Due
to recent rainfall and light winds fog is possible at KDLH, KHIB
and KHYR between 08z and 11z, and have only put in MVFR
visibilities for now. Convection may redevelop to affect KINL and
KBRD after 18z, but confidence in timing and coverage is low and
have left out for now.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 47 70 48 64 / 30 10 30 60
INL 46 71 46 63 / 0 20 30 50
BRD 48 72 49 67 / 0 10 20 40
HYR 48 72 49 68 / 70 10 30 50
ASX 48 71 49 66 / 70 10 30 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
UPDATE...LE
SHORT TERM...GSF
LONG TERM...Huyck
AVIATION...LE
Area Forecast Discussion
National Weather Service Peachtree City GA
954 PM EDT Fri May 26 2017
.UPDATE...
Current forecast in good shape through Sat morning with just some
high clouds moving through. Am a little more concerned about
convective potential...now as early as Saturday morning. Now
granted we are tracking a parent shortwave still over the Texas
panhandle...but models showing increased instability for the
northern tier with over 3000 J/KG. There will be a moderate cap
in place to start the day but should quickly erode with
approaching MCS and shortwave. Plus these type of NW flow events
dont typically care too much about any cap in place. For now will
increase pops to high end chance but if model trends
continue...may need likely for a large portion of the North.
Timing will be challenging with latest HRRR as early as 15Z.
Think this may end up being a bit early and will lean more toward
afternoon.
Deese
&&
.PREV DISCUSSION... /issued 753 PM EDT Fri May 26 2017/
PREV DISCUSSION... /issued 331 PM EDT Fri May 26 2017/
SHORT TERM /Tonight through Saturday Night/...
High pressure over the region will shift southeast into Saturday.
Have continued with slight chance to chance pops across far north
Georgia late Saturday afternoon as models continue to advertise
a frontal boundary settling over the Tennessee Valley, with
convection firing along it. At this time, modeled surface
instabilities, steep lapse rates and deep layer shear could result
in strong to severe storms. That being said, at least for now,
coverage of these stronger storms should be low, with some hi-res
solutions not even advertising any of the thunderstorm activity
working its way into the state. Have continued with a forecast
compromise with a blend of the models. For any strong storms that
develop/move over the area, expect the main hazards to be gusty
winds and hail.
31
LONG TERM /Sunday through Friday/...
No major changes were made to the long-term forecast. Main focus
continues to be increasing potential for convection by late Sunday
into Monday. Refer to the previous long-term discussion below for
additional details.
RW
/Issued 406 AM EDT Fri May 26 2017/
Primary concern in the long term period is deep convection
associated with baroclinic zone forecast to sag into the state
late Sunday and Monday.
00Z medium range guidance in fair agreement that front will slip
in Monday and that lift and resulting rainfall will be less than
what we have seen with last few systems this month. Overall
pattern favorable for strong/severe storms in SWly flow aloft on
periphery of upper ridge which extends from TX to OH/TN valleys
thru Monday. GA appears to be mostly dry, dominated by upper
ridging thru late Sunday, though far northern areas could see a
few storms slip in, especially if a large MCS could develop in TN
and propagate SE. Instability should be sufficient for
strong/severe storms, should any make it into the state, however
vertical wind shear will be weak, especially as you go further
south away from stronger westerlies along periphery of ridge.
Front finally pushes through Monday night/Tuesday but with no
well defined short wave, not much lift will accompany its passage.
As front stalls over far south GA, should see mostly dry weather
until Wed night or Thursday when warm advection ahead of weak,
nearly stalled southern stream wave over TX and lower MS valley
brings moisture back. Total rainfall Sunday-Tuesday likely to be
0.5 to 1 inch in north GA and less than 0.5 inch elsewhere.
SNELSON
AVIATION...
00Z UPDATE...
VFR conditions to be maintained this forecast despite a few models
showing some MVFR potential Sat afternoon. This seems a stretch
but do anticipate TSRA to the north to bring BKN050 down to the
ATL terminals. Did not include VCSH at this time to terminal but
may be needed with next forecast. Also added some low end wind
gusts.
//ATL CONFIDENCE...00Z UPDATE...
Medium on Sat cig potential.
High on remaining elements.
Deese
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 64 88 69 89 / 0 20 20 20
Atlanta 65 87 71 87 / 0 10 10 10
Blairsville 60 82 63 82 / 5 50 30 40
Cartersville 63 86 69 88 / 0 20 20 20
Columbus 64 89 71 90 / 0 0 10 10
Gainesville 65 85 69 86 / 0 30 30 20
Macon 62 90 68 91 / 0 0 10 10
Rome 63 85 68 87 / 0 30 30 30
Peachtree City 61 87 68 88 / 0 10 10 10
Vidalia 64 91 70 94 / 0 0 5 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Deese
LONG TERM....20
AVIATION...Deese
Area Forecast Discussion
National Weather Service Green Bay WI
1053 PM CDT Fri May 26 2017
Updated aviation portion for 06Z TAF issuance
.SYNOPSIS...
Issued at 251 PM CDT Fri May 26 2017
Scattered showers and gradually turning cooler during the holiday
weekend.
Northwest upper flow will develop across the region as a ridge
sets up over western North America and an upper trough settles in
over Ontario. The pattern does not appear as though it will be
exceptionally long-lived, as deamplification is likely to begin by
late in the period.
Temperatures will start the period near seasonal normals, then
drop back to a little below normal in the developing northwest
flow. There will be several opportunities for precipitation, but
most precipitation events look to be composed of scattered to
numerous showers so amounts are likely to end up near normal for
the 7 day period.
&&
.SHORT TERM...Tonight and Saturday
Issued at 251 PM CDT Fri May 26 2017
Precipitation chances remain somewhat uncertain due to weak
forcing. Trended PoPs upward this evening and then down after
midnight, following the most recent HRRR runs. Remnants of a weak
boundary will linger across the area Saturday, again leading to
rather nebulous forcing. Stuck with mainly chance PoPs with the
best chance in the afternoon.
Dense fog over Lake Michigan has primarily remained offshore, but
southeast low-level flow could bring it inland. The main concern
is highways near the lake which are likely to have a high traffic
volume at the start of the holiday weekend. Plan to handle the
situation with SPSs unless fog makes a more aggressive surge
inland. Winds may turn offshore later tonight and push the fog
farther out into the lake, but again models differed in the
details of that in the weak low-level pattern.
.LONG TERM...Saturday Night Through Friday
Issued at 251 PM CDT Fri May 26 2017
Northwest flow aloft will continue through much of next week as
500mb ridge remains entrenched across western North America with a
downstream trough across eastern North America. Upper level
disturbances and associated weak cold fronts will bring periodic
chances of showers and a few thunderstorms from time to time
through much of the period.
For Saturday night, weak frontal boundary across the area,
combined with daytime heating will allow for scattered shower to
linger into the evening hours. A thunderstorm could not be ruled
out. After midnight, two systems will approach the area. The first
system will pass to the south of the area while the second system
will approach from the northwest. These two systems will bring
increasing chances of showers overnight into Sunday morning. The
next weak cold front will move across the area Sunday afternoon.
This feature will bring continued chances of showers with a few
thunderstorms expected. Most of the shower activity will end
during the evening hours. With northwest flow aloft, could not
rule out an isolated shower after midnight.
Next shortwave energy and upper trough swing across the area
on Memorial Day. With daytime heating, instability showers will
be on the increase during the late morning and afternoon. A few
thunderstorms are possible. Due to expected cloud cover and rain,
lowered high temperatures on Memorial Day. Also, gusty westerly
winds are expected with gusts around 30 mph possible.
More instability showers are expected Tuesday, and again Wednesday
and Thursday. Most of the time will be dry, however the best
chances of rain appear to be during the afternoon hours.
Temperatures during the period will be at or slightly below
average.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1050 PM CDT Fri May 26 2017
Scattered showers were weakening as they approached north central
WI late this evening, and will likely not survive to reach RHI.
Partial clearing, light surface winds, boundary layer winds of 15
knots or less and low-level moisture will likely lead to areas of
fog and low clouds late tonight, with localized LIFR/VLIFR flight
conditions possible. Dense fog is also possible along the
lakeshore overnight, but whether or not this will impact the MTW
TAF site is uncertain. The fog should mix out early Saturday
morning. Daytime heating and the presence of a weak boundary in
eastern WI may result in scattered showers and isolated
thunderstorms late in the afternoon/early evening. Will mention
VCSH at GRB/ATW/MTW, but confidence is not high enough to mention
thunderstorms at this time.
&&
.MARINE...
Issued at 251 PM CDT Fri May 26 2017
Dense fog will continue tonight into Saturday on Lake Michigan.
Patchy dense fog is also possible on the Bay of Green Bay. The
fog may linger into Saturday night on Lake Michigan. There is
a slight chance of thunderstorms during the afternoon and
early evening hours Saturday, Sunday and Memorial Day that may
pose a hazard to mariners.
Gusty westerly winds are expected on Memorial Day with gusts
around 25 knots possible making for hazardous conditions for
small craft.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......Eckberg
AVIATION.......Kieckbusch
MARINE.........Eckberg
Area Forecast Discussion
National Weather Service Wichita KS
918 PM CDT Fri May 26 2017
.UPDATE...
Issued at 918 PM CDT Fri May 26 2017
Despite a few tweaks to the forecast, overall thinking remains the
same. Thinking eastern Colorado and northwest Kansas
thunderstorms will gradually congeal into a thunderstorm complex
and affect central and north-central Kansas after midnight, given
continued moist/unstable southeasterly low-level flow along with
increasing large scale ascent from shortwave energy approaching
over the Rockies. Ample instability and effective deep layer shear
will support isolated occurrences of severe hail/wind, along with
locally heavy rainfall rates. This activity should tend to weaken
with eastward extent (east of I-135). Attention then turns to the
potential for a second thunderstorm complex to progress out of
Nebraska and into northern/central Kansas late tonight into early
Saturday morning, as the main cold frontal zone ahead of the
shortwave approaches from the northwest. Given the increasingly
unstable airmass, this activity has a decent chance of being
strong/severe across the eastern half of Kansas. If this
secondary thunderstorm complex develops a massive cold pool, it
would probably act to speed up the effective cold frontal zone,
which may reduce afternoon severe chances.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 308 PM CDT Fri May 26 2017
Tonight-Saturday:
Potential for high impact storms is main focus. Three different
scenarios possible. First is GFS/NAM camp focusing convection
across Central KS tonight and then Saturday afternoon development
in Southeast KS on the surface front. Second is all HRRR runs
today and 0000 UTC ECMWF which have a more southern track with
Western KS storms rolling east overnight into area around daybreak
and then remnant MCV/MCS dropping into Central KS from Western
Nebraska. The HRRR/ECMWF solution would result in a much earlier
severe weather threat on Saturday that would include entire area
along/south of highway 400. This early threat would be mainly
wind, with potential to go upscale during the morning as storms
move into increasingly moist airmass. Northern outflow would
impact storms moving south from Nebraska. If the NAM/GFS scenario
plays out, threat would more likely include supercells with storms
going up on front. Finally, the 1200 UTC ECMWF has a slightly
different take, with Western KS storms dissipating very late
tonight about the time they reach ICT. The Western Nebraska storms
remain strong-severe overnight diving southeast across the
forecast area early in the day and into SW MO in the afternoon.
This scenario is not that far fetched either given 1200 UTC upper
air plot showing axis of higher 850MB dewpoint from TOP to LZK.
The main threat from this would be high winds. At this point, have
leaned official forecast toward the HRRR/ECMWF solution, although
hedging with slightly higher pops in Central KS to account for
storms moving in from Nebraska. Plan to broadbrush the hazardous
weather outlook to account for the various sceneries. -Howerton
Sunday-Monday:
Sunday will feature mild temperatures and dry weather as high
pressure builds over the area. Another weak front moves into the
area Monday afternoon. Anticipate airmass will be too dry for
storms, but latest GFS/ECMWF dribble out spotty patches of a
hundredth or two of QPF Monday afternoon.
.LONG TERM...(Tuesday through Friday)
Issued at 308 PM CDT Fri May 26 2017
Broad trough across the Central US and baroclinic zone in the
plains spells trouble for forecasters. Timing of weak ripples in
northwest flow and location of boundary is notoriously difficult.
Storms likely over the high plains tracking southeast during the
night and not a whole lot of consistency with these smaller scale
features. Precipitation chances will likely increase through time
as low level moisture increases. -Howerton
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 724 PM CDT Fri May 26 2017
Main aviation concern is the potential for thunderstorms after
midnight through Saturday. Thinking the highest confidence
scenario is activity reaching central Kansas around midnight,
with another round possible later tonight into Saturday morning
central/north-central and northeast Kansas. Will likely be making
amendments as the evening progresses watching radar trends.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 64 83 58 80 / 20 20 10 0
Hutchinson 62 81 56 79 / 30 20 10 0
Newton 63 81 56 78 / 30 20 10 0
ElDorado 64 83 58 79 / 20 30 20 0
Winfield-KWLD 65 87 59 80 / 10 30 20 0
Russell 60 75 53 78 / 40 40 10 0
Great Bend 60 77 53 78 / 40 30 10 0
Salina 63 79 56 80 / 40 30 10 0
McPherson 62 80 55 78 / 40 20 10 0
Coffeyville 67 87 61 79 / 10 50 40 10
Chanute 66 84 60 79 / 10 50 30 10
Iola 65 83 59 79 / 10 50 30 10
Parsons-KPPF 67 86 61 79 / 10 50 40 10
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...ADK
SHORT TERM...PJH
LONG TERM...PJH
AVIATION...ADK
Area Forecast Discussion
National Weather Service Wilmington OH
1118 PM EDT Fri May 26 2017
.SYNOPSIS...
An unsettled weather pattern will be in place for the weekend
with multiple systems moving through the region. Mostly dry
conditions return for Monday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Quick update to cancel Severe Thunderstorm Watch #270. It has
become clear from radar imagery -- mottled reflectivity and
smooth velocity -- that these storms have transitioned to being
elevated, with only low chances of strong winds still making it
to the surface. Recent RAP model data suggests that the expected
low level jet is just beginning to kick in, meaning that there
has not been time to generate much in the way of even elevated
instability for these storms to feed on. Nonetheless, some heavy
rain will be possible as the storms clear the forecast area in
the next few hours.
Previous discussion >
Showers and thunderstorms are currently approaching from the
west. SPC has put the western area under Severe Thunderstorm
Watch 270 until 2 AM. Latest high res models show the storms
slowly weakening as they dive across the region. Latest NSSL WRF
is doing a fantastic job so have trended grids this direction. New
zones already out.
Previous Previous Discussion->
A few showers will move across northwestern portions of the
forecast area through the early evening hours. A MCV or meso
low approaches tonight along with upper support. There are still
some model differences in the exact location of this low and
subsequently precipitation coverage. Better instability is
across central and southern portions of the region.
Thunderstorms could end up a little further south than some of
the model indications are if the thunderstorms build into the
better instability. In general expect a bow of thunderstorms to
move into western portions of the forecast area beginning around
8pm. Since there is a boundary nearby there is the potential
for an isolated tornado. The main threat would be damaging
winds. Cannot rule out isolated flooding since there will be
heavy downpours, however the precipitation is expected to be
relatively progressive. There is a smaller threat for large
hail.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Precipitation will be exiting the area at the start of the day
on Saturday with only a few residual showers and storms south of
the Ohio River. Additional thunderstorms are expected to
develop along and south of the Ohio River Saturday afternoon
along a frontal boundary. Damaging winds and large hail will be
possible with these storms. Additional showers and thunderstorms
are expected to work into the region overnight associated with a
warm frontal boundary. There is another severe threat during
this time with damaging winds and large hail. There is some
concern for flooding and isolated tornadoes well.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
A warm front is forecast to lift north across Ohio Sunday morning
ahead of a surface low pressure system moving across the southern
Great Lakes. There is some uncertainty as to how things will play
out with a possible MCS Saturday night and the effects this may have
on our area into Sunday. Nonetheless, it does look like we should
destabilize as we get more into the warm sector as we head through
the day on Sunday. As the low moves across the southern Great Lakes,
an associated cold front will drop southeast through our area Sunday
night. Ahead of this, will continue with higher chance to likely
pops through the day on Sunday and then taper them off from the
northwest Sunday night as the cold front moves through. Expect highs
on Sunday mainly in the upper 70s.
An upper level low will rotate down across the Great Lakes and then
shift slowly off to the east through mid week. A series of weak mid
level short waves could lead to a few showers across our far north
Monday and Tuesday. There is some model uncertainty on Wednesday
with maybe some slightly stronger energy moving in from the
southwest. For now will just allow for a low chance of showers and
perhaps a thunderstorm later Tuesday night into Wednesday across the
area. The upper level low will weaken as it shifts to the northeast
United States through the end of the week. This will help us
transition into more of a southwest flow pattern with the possibility
of some lower chance pops developing toward the end of the long term
period. Seasonable temperatures will continue through the week with
highs in the 70s.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
All TAF sites currently VFR this evening with a line of showers
and thunderstorms approaching from the west. These showers and
thunderstorms will push southeast into the TAF sites this
evening with KCVG/KLUK being on the edge. The complex of showers
and thunderstorms will then likely weaken as they move into the
TAF sites from the west. As the upper level disturbance/
showers and thunderstorms head east of the TAF sites early
Saturday morning IFR/ MVFR cigs will move in. MVFR cigs will be
slow to lift Saturday morning and hang around potentially into
the early afternoon. TAF sites will eventually go VFR Saturday
afternoon with a weak cold front stalling across southern Ohio.
Some high res are indicating showers and thunderstorms along the
weak boundary Saturday afternoon but looking at forecast
soundings shows a CAP in place around 800 MB. This will likely
keep the TAF sites convection free Saturday afternoon. Towards
the end of the TAF issuance the boundary will wash out with a
potent upper level disturbance approaching from the west.
OUTLOOK...Intermittent chances of thunderstorms along with MVFR
ceilings will be possible from Saturday through Monday morning.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Haines/Novak
NEAR TERM...Haines/Hatzos/Novak
SHORT TERM...Novak
LONG TERM...JGL
AVIATION...Haines
Area Forecast Discussion
National Weather Service Lincoln IL
905 PM CDT Fri May 26 2017
.UPDATE...
Issued at 905 PM CDT Fri May 26 2017
Upper level shortwave associated with severe thunderstorm activity
across central IL this afternoon and evening is now east of
Illinois with subsidence behind the feature causing diminishing
shower and thunderstorm activity. Nevertheless, a band of showers
and potentially an isolated thunderstorms extends from northern
Vermilion County westward toward Springfield along an outflow
boundary from the previous convection. This boundary is expected
to sink slowly southward promoting at least a slight chance of
thunderstorms along the I-72 corridor through late evening and
into the I-70 corridor in the early morning. Light winds and moist
conditions following rainfall will promote some potential for fog
across the area overnight. Northern Vermilion county should see
locally dense fog in areas that receive prolific hail this
evening. Updates have been sent this evening regarding the above
features.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 259 PM CDT Fri May 26 2017
Clusters of thunderstorms along the southern periphery of an MCV
will track across north-central Illinois this afternoon into the
early evening. Based on radar trends and output from the HRRR and
3km NAM, it appears locations along/north of the I-74 corridor will
be impacted through about 00z/7pm. As a result, have increased PoPs
to likely across this area through the remainder of the afternoon.
Once this system races into Indiana, it will drag a weak cold front
southward into central Illinois this evening. With strong WAA
occurring throughout the entire depth of the atmosphere, mid-level
capping will be strong enough to prevent much convection from
developing along the trailing front. Have therefore only carried
slight chance PoPs across the southern two-thirds of the KILX CWA
from mid-evening through the overnight hours. With the boundary in
the vicinity, winds are expected to become light/variable. Given
increasing boundary layer moisture (both from advection and any
rainfall that occurs this afternoon), think fog will develop
tonight. HRRR continues to show fog developing along the I-74
corridor by around midnight, then spreading further southward across
the remainder of the area as the night progresses. Have added
patchy fog across the board accordingly.
Frontal boundary will stall along the I-70 corridor late tonight
through Saturday and will eventually serve as a focusing mechanism
for strong to potentially severe convection late Saturday. Latest
models have continued to trend later with the next round of storms,
with most high-res solutions shifting the emphasis into the evening.
Given good consensus that Saturday will be dry, have dropped PoPs
until late in the afternoon across the far SW CWA. Main event will
arrive Saturday evening, with models still not set on an exact
timing just yet. NAM/GFS are the fastest models, with convection
developing upstream across Kansas during the afternoon...then
tracking eastward along the boundary and arriving in west-central
Illinois by early evening. Meanwhile, other convective-allowing
models such as the WRF-NMM and WRF-ARW delay the arrival of the
convection until late evening into the overnight hours. Storm mode
by the time the system arrives will be linear, so damaging wind
gusts with an isolated tornado threat would be most probable. At
this time, have gone with likely PoPs across the western half of the
CWA during the evening, then further east to the Indiana border
after midnight. If trends continue, the timing may eventually need
to be adjusted a bit later.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 259 PM CDT Fri May 26 2017
Once the Saturday night wave of convection passes to the east, it
will give the stalled frontal boundary a push to the south on
Sunday. Airmass destabilizes ahead of the front by afternoon,
resulting in scattered thunderstorm development primarily along and
south of I-70. Have included 30 PoPs across this area, with little
or no precip expected further north across the remainder of the
area. High temperatures on Sunday will reach the middle to upper
70s.
Pronounced upper low will dig southward through Ontario into the
Great Lakes early next week, resulting in a cooling trend across
central Illinois. A weak surface trough will sink southward around
the parent low on Monday, potentially bringing a few showers.
Convergence along the boundary will be weak and with the main upper
cold core still to the north, think areal coverage of precip will
remain low. As a result, have only mentioned slight chance PoPs for
showers/thunder along and north of I-74 Monday afternoon. Cool/dry
conditions will prevail Monday night into Tuesday before the next
potential system spreads showers across south-central Illinois
Tuesday night. After that, mainly dry weather is expected until a
stronger system brings the next chance for rain by Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 643 PM CDT Fri May 26 2017
Main cluster of convection has now pushed into west-central
Indiana:however, a trailing outflow boundary may trigger isolated
storms for the next couple of hours at the I-72 terminals. Have
carried VCTS at KSPI/KDEC/KCMI through 01z accordingly. Once any
early evening convection dissipates, winds will become
light/variable behind the boundary. Due to increasing low-level
moisture and rainfall across the northern counties this afternoon,
fog will develop overnight. HRRR has been consistently showing
fog developing along the I-74 corridor around midnight, then
slowly spreading southward toward dawn. Will reduce visbys to
around 2 miles between 09z and 13z at all sites. After the morning
fog lifts, mostly sunny skies will be noted through Saturday
afternoon.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...37
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Barnes
Area Forecast Discussion
National Weather Service Indianapolis IN
1138 PM EDT Fri May 26 2017
.UPDATE...
The AVIATION section has been updated below.
&&
.SYNOPSIS...
Issued at 152 PM EDT Fri May 26 2017
An active weather pattern is taking shape for this weekend.
HIgh pressure over Indiana is expected to quickly move east...this
afternoon as a weak low pressure system over Illinois quickly
moves across Northern Indiana tonight. This will spread showers
and storms across the northern part of the state tonight.
A weak high pressure system will then settle across the area for
Saturday...bringing more dry weather for much of the day. Another
quick moving upper level weather disturbance will arrive in the
area on Saturday night. This will bring another round of showers
and storms to Indiana.
Dry weather is expected on Sunday morning before a cold front is
expected to pass on Sunday afternoon and evening. Once again, this
may bring a round of showers and storms.
Slim Storm chances will linger on Monday as broad cyclonic flow
will remain across the region...however many dry hours will be
expected.
With the exception of a secondary front bringing low chances for
storms Tuesday...expect primarily dry weather for much of next
week with seasonable temperatures.
&&
.NEAR TERM /Rest of Tonight/...
Issued at 934 PM EDT Fri May 26 2017
Thunderstorm complex moved southeast across the area and has
produced severe weather. The storms are trending down at the moment
though. Have upped PoPs to reflect where these storms are and will
be in the next couple of hours.
Meanwhile, additional thunderstorms continue to develop to the
northwest of the forecast area. Unstable air continues to flow into
the area above the cold pool from the thunderstorms. Thus hail
remains a threat. After coordinating with the Storm Prediction
Center, have already expanded the Severe Thunderstorm Watch back
northwest across the forecast area. Will continue to monitor trends
to see if the watch needs to go all the way to 2 AM though.
Remainder of forecast looks ok with only minor changes to low
temperatures.
Previous discussion follows...
Surface Analysis early this afternoon shows a ridge of high
pressure over the Indiana/Ohio boarder. Compact Low pressure was
found over western Illinois...surging eastward. Southerly flow was
in place across Indiana with dew points in the 50s. Water vapor
imagery shows a short wave associated with the over
Iowa...drifting NE.
GFS and NAM suggests the short wave will progress northeast
across NRN Illinois toward Michiana. Rapid refresh depicts
convection development mainly across the northern parts of the
state from 22Z-03Z...progressing eastward. Southern parts of the
convection area may be overdone. Forecast soundings show
convective temperatures in the middle 80s and 700mb temps are near
8C...providing good cap. Thus the HRRR appears a bit over done
with the southern extent of the showers and storm development this
evening. Still Pop will be warranted given the dynamics...just
will limit the highest pops to the northern areas as those
locations will be in a better position to receive precipitation.
Furthermore will taper pops off by 05Z-07Z as the wave aloft
should be quickly departing by that time.
Models appear in good agreement on temps and will stick close to
the blend on expected lows.
&&
.SHORT TERM /Saturday through Monday/...
Issued at 152 PM EDT Fri May 26 2017
Confidence in a dry Saturday is high. Forecast soundings and Time
heights reveal a dry column. Weak high pressure in the wake of the
departing low looks to be in place across the southern Great
lakes...providing northerly flow. However...this does result in a
warm front taking shape along the I-70 corridor...which will come
in to play later.
Thus will trend toward a partly cloudy sky on Saturday along with
a blend on highs which should result in an outstanding weather
day.
Things change on Saturday night as the high quickly departs and
another more organized shortwave pushes toward Central Indiana
from the Central Mississippi valley. Positioning for this wave is
much more favorable for Central Indiana...along with the some
surface convergence available due to the lingering boundary that
was previously mentioned. Models have backed off on the amount of
instability as compared to yesterday...with CAPES now generally
less than 1000 g/kg on Saturday night. While this will diminish
the severe threat somewhat...showers and storms still cannot be
ruled out given the expected dynamics. Will raise pops from the
MAVMOS here...and trend lows toward wetbulbs.
Confidence continues to grow for Dry weather on Sunday morning and
early afternoon. GFS and NAM suggest that Indiana will once again
be caught between two short wave at that time...as the Saturday
Night system will have departed and the the next wave appears to
be over Illinois...poised to arrive by late afternoon. Thus
forecaster builder willing...we will try to keep pops out of the
morning hours and begin a ramp up on Sunday mid-afternoon and
evening as the expected dynamics approach from the west. Again a
blend on highs will work fine.
GFS suggests the quick moving wave should depart the area by 03Z-
05Z. Forecast soundings suggest rapid drying and subsidence in its
wake. Thus will quickly taper pops toward dry on late Sunday
night...trending temps at or below the blend.
Models then depict broad cyclonic flow across the Great Lakes and
Indiana on Monday. Yet another short wave is suggested to push
through the circulation toward Central Indiana...but confidence for
precip will be low at this point given the generally expected
northwest flow of air to Central Indiana in the wake of the cold
front. Still at this time forecast soundings are suggesting steep
lapse rates and attainable convective temperatures...thus weak and
light instability showers in the afternoon do not appear out of the
question.
&&
.LONG TERM /Monday Night through Friday/...
Issued at 207 PM EDT Fri May 26 2017
Ensembles in fairly good agreement during this period. An upper low
will gradually shift east across the upper Great Lakes during the
early parts of the extended, with the flow flattening out later next
week.
Ensembles suggest an upper disturbance may rotate through the area
around the upper low in the Tuesday night or Wednesday time frame.
Will put some chance PoPs in the forecast during those periods to
cover this feature.
Some of the ensembles suggest an upper disturbance may eject out of
the southwest into the local area by late next week. Will put some
chance PoPs in for next Friday at this time, however they may be
needed for Thursday as well if the faster solutions come to pass.
&&
.AVIATION (Discussion for the 270600Z TAF Issuance)...
Issued at 1138 PM EDT Fri May 26 2017
Conditions expected to deteriorate to IFR overnight, then gradually
improve to VFR by Saturday afternoon.
Convection has ended across the area. MVFR then IFR conditions will
develop overnight. There remains some uncertainty on the timing, but
may start out with MVFR from beginning of valid time. Will watch
trends and make final decision at issuance time.
Expect some fog to develop, especially at KLAF/KIND where it rained
Friday evening.
Fog will burn off first Saturday morning, followed by a slow
improvement of clouds, with all sites returning to VFR by afternoon.
Convection looks to hold off until late in the valid period, so left
mention out for now.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Puma
NEAR TERM...Puma/50
SHORT TERM...Puma
LONG TERM....JAS
AVIATION...50
Area Forecast Discussion
National Weather Service Paducah KY
653 PM CDT Fri May 26 2017
.UPDATE...
Issued at 653 PM CDT Fri May 26 2017
Updated aviation discussion for 00Z TAFs.
&&
.SHORT TERM...(Tonight through Sunday night)
Issued at 334 PM CDT Fri May 26 2017
Will keep current wind advisory in place through expiration as
winds remain strong enough to hamper some outdoor activities on
area lakes and rivers.
Very complicated and conditional severe weather scenarios in place
for the Memorial Day Weekend. A similar signal was noted in the
ECMWF, Canadian, NAM-WRF (including the NMM Version), and the ESRL
HRRR and was used in the background for the timing and coverage of
the convective activity tonight through Sunday.
GOES 16 Visible satellite imagery and surface observations
pointing to broad lift and mixing under the low level inversion
with a flat ridge. Stable layer cloud cover is showing up near the
maximum moisture plume over Southeast Missouri and Southern
Illinois at this time. There is uncertainty whether there will be
enough lift for showers (or drizzle) this evening over Southeast
Missouri. The Convection Allowing Models (CAM) suggest that there
may be some isolated shower or thunderstorm activity along the
differential heating boundary east of the cloud cover. This will
need to be monitored for tonight.
The MCS/MCV over northern Illinois at this time should provide
some further lift as it moves southeast into Indiana this evening.
This will likely generate a focused boundary along and north of
the Interstate 64 corridor in Southern Illinois and Southwest
Indiana. This will provide some potential isolated convective
activity along Interstate 64 tonight into early Saturday.
A rich source of moisture will continue to advect from Arkansas
overnight tonight into Saturday morning with an impressed warm
frontal boundary setting up across Southeast Missouri, loosely
connected to the left over boundary along the interstate 64
corridor in Southern Illinois and Southwest Indiana. With
precipitable water expected near two inches, decent rainfall rates
will be possible near the frontal boundary in Southeast Missouri
during the early morning hours Saturday. Low to middle level flow
will be well into a faster zonal flow with decent shear available
for robust updrafts by midday Saturday. Given the increasing
shear, ample CAPE, and the proximity to boundaries, there will
significant severe weather potential, especially during the
afternoon and evening. Very large hail and damaging winds, and the
potential of a tornado near an outflow boundary will be expected,
especially in the SPC Moderate Risk area.
There may be a reduction in severe weather coverage and intensity
by mid-evening, but will pick up again around the midnight hour
when a well-organized linear MCS is expected to move southeast
through Missouri, reaching into Southeast Missouri and Southwest
Illinois. There may be more widespread, enhanced wind damage
potential with this MCS overnight.
The big question will be what happens to the MCS once it moves
into the WFO PAH forecast area after midnight. Should the MCS move
beyond its mature stage shortly after midnight into early Sunday
morning, there will be a rapid slow down/stalling of the outflow
and fixation of a impressed boundary over the WFO PAH forecast
area between 3 am and 8 am Sunday. If the thunderstorms stall and
train, excessive rainfall will be the primary weather hazard
through daybreak Sunday. This would set the stage for renewed
strong to severe convection on Sunday afternoon, as the upper
low/trough move into and through the WFO PAH forecast area.
Should thunderstorms move further south into West Kentucky late
Saturday night/early Sunday morning, the SPC Day 3 Slight Risk of
Severe Thunderstorms may need to be adjusted further to the
southeast of the area.
Regardless, it will be dicey for anyone attending/participating in
outdoor activities this weekend.
.LONG TERM...(Monday through Friday)
Issued at 334 PM CDT Fri May 26 2017
This period will start out with high pressure moving through behind
Sunday`s frontal passage. For those with outdoor activities on
Memorial Day, the weather looks fantastic with dry weather and lower
humidity levels.
A weak cold front will sink south toward the area by Monday evening
as an upper level low churns over the Great Lakes region. Cyclonic
flow around this upper feature will continue to cause disturbances
to rotate around it. The influence of these waves will largely stay
north of our region, but there looks to be some minor ripples move
up from the southwest U.S. that may interact with the weak front
nearby and produce some minor precipitation for Tuesday and
Wednesday. Individual models aren`t in great agreement so the
blended guidance seems to be a good approach at this time range.
Rain chances will ramp up later in the week as the upper low over
the Great Lakes finally pushes east on Thursday. Eventually our area
looks to become entrenched in southwest flow with increasing
moisture later in the week. This will lead to increased shower and
thunderstorm chances Wednesday night through Friday.
Temperatures will remain right around normal for late May. Highs
will generally be in the upper 70s to lower 80s with night time
temps dipping into the upper 50s to lower 60s.
&&
.AVIATION...
Issued at 653 PM CDT Fri May 26 2017
VFR ceilings will persist across much of the area through the
evening, while MVFR conditions prevail over portions of southeast
Missouri and southern Illinois. Patchy drizzle is even possible
beneath the MVFR ceilings this evening. Ceilings are expected to
lower into the MVFR range across most of the area late tonight into
early Saturday morning. They should return to VFR category by the
late morning and afternoon hours Saturday. A little MVFR fog
development is possible late tonight--particularly over southeast
Missouri which may impact KCGI. While isolated storms cannot be
completely ruled out through noon Saturday, we believe the greatest
risk for thunderstorm development should hold off until late
Saturday afternoon and evening. Southerly winds AOB 10 knots will
prevail.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
SHORT TERM...Smith
LONG TERM...SP
AVIATION...RJP