Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/17/17
Area Forecast Discussion
National Weather Service Wakefield VA
1038 PM EDT Fri Jun 16 2017
.SYNOPSIS...
A weak boundary lifts north of the area through tonight with
warm conditions expected through the weekend. Scattered
afternoon and evening showers and thunderstorms are expected
again Saturday with less coverage expected Sunday. A cold front
slowly approaches the region from the west on Monday, stalling
over the region through the middle of the week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Areas of moderate to heavy rain continue this evening in a moist
airmass despite weak forcing aloft. Adjusted PoPs based off
latest radar trends and HiRES guidance. Also have issued a FFW
for areas just north of Richmond where there are several reports
of water on roads. This has been fairly localized however, with
no other areas needing any FFW/FLS.
Previous Discussion...
Anomalously moist air mass remains over the local area as
satellite and RAP guidance indicates precipitable waters around
1.9 to 2.1 inches. Shortwave energy over the Southeast has
pushed the weak frontal boundary northward into northeast North
Carolina, stretching northwestward over the Piedmont. The front
has been the focus for widely scattered to scattered showers and
thunderstorms across southeast Virginia/northeast North
Carolina and the Piedmont. Earlier cloud cover limited overall
instability, but RAP analysis indicates mixed-layer CAPE of
1000-1500 j/kg (up to 2000 j/kg over the far southeast. A wave
is progged to lift northeast over the Piedmont later this
afternoon into this evening, leading to better organization and
coverage late today into this evening. Storms are expected to
grow upscale, lifting northeast. Best coverage expected across
the Piedmont and the southeast half of the forecast area,
remaining more scattered into central Virginia. Heavy rainfall
remains the main threat. Temperatures in the upper 70`s to low
80`s have limited downdraft potential (DCAPE) and deep layer
shear is less than 20 knots, but gusty winds are possible under
the strongest storms.
Added dynamics and elevated instability expected to keep showers
and thunderstorms ongoing through the evening hours west of the
Bay. Have retained likely POPs inland this evening. Convection
wanes late tonight, but will maintain a slight chance POP inland
due to the warm/moist air mass. Mild, with lows around 70.
Another night of low clouds and patchy fog expected.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Warm/moist return flow persists over the region Saturday as
high pressure remains centered over the western Atlantic. Low
pressure centers over the Great Lakes as the attendant cold
front remains well west of the local area. Aloft, a baggy trough
stretches from the Ohio Valley into the Deep South as the
subtropical ridge locates offshore. While the air mass remains
quite warm and unstable, a lack of appreciable forcing and a
lack of surface convergence expected to result in only scattered
afternoon and evening showers/thunderstorms. Warming between
850-700mb also expected to prevent robust updrafts. Best chances
expected near the coast associated with sea-breeze boundaries
and remnant outflow boundaries. Highs in the mid to upper 80`s.
Cooler near the coast. Mild Saturday night with lows generally
in the low 70`s. Given the air mass, have kept slight chance to
chance POPs through late Saturday night.
Little change aloft Sunday as the baggy trough remains over the
Southeast. Stronger return flow expected Sunday ahead of an
approaching cold front. Precipitable waters fall off to 1.5 to
1.75 inches. Warming aloft and mid-level lapse rates less than 6
C/km will limit overall instability, with guidance indicating
mixed-layer CAPE values less than 1,000 j/kg. Perturbations in
the southwest flow will provide some subtle forcing for ascent,
so anticipate widely scattered to scattered showers and
thunderstorms Sunday afternoon and evening across the Piedmont
and near any sea-breeze boundaries. Warm, with highs in the
upper 80`s to low 90`s. Dry and mild Sunday night with lows in
the low to mid 70`s.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Rather typical late-Spring/early-Summer conditions are
expected to continue into next week. A trough digging over the Great
Lakes will push a cold front toward the area Monday into Monday
night, resulting in an increasing chc of aftn/evening showers/tstms
Monday aftn/Monday night. Increasing flow aloft and a moderately
unstable airmass could trigger some locally strong storms with heavy
rain. The front lingers in vicinity of the coastal plain of SE VA
and the Carolinas Tuesday/Wednesday resulting in 20-30% PoPs Tuesday
and aob 20% by Wednesday. The latest data supports dry conditions by
Thursday as the boundary washes out. Another boundary/trough may
settle into the area by Friday but uncertainty is high at this time.
Highs Monday are generally in the upper 80s to around 90, then
dropping back to the mid/upper 80s by Tuesday/Wednesday as the front
gradually pushes through the area. By Thursday/Friday highs return
to the upper 80s to around 90. Lows will generally by in the upper
60s to low 70s through the period.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Widespread showers and thunderstorms are on a slow decrease this
evening and the heaviest rain looks as though it will miss all
the TAF sites though there will be vicinity shra and tsra at
RIC through 01z. Some light rain is possible at PHF and RIC
through 02z, but visibility should remain 5sm or better. Overall
ceilings are generally VFR with a few pockets of MVFR. however
think the TAF sites will all remain VFR for the remainder of the
evening. Winds have become variable across the region due to
outflows from storm activity, but should return to generally
south to southeast at 5 knots or less. The boundary lifts
northward tonight into central Virginia, as flow becomes more
southerly over the region. The air mass remains quite warm and
moist, so expect another round of low ceilings to develop
towards daybreak with areas of fog developing again tonight.
Scattered to numerous showers expected again Saturday afternoon
and evening. Stronger southwest flow Sunday and Monday and less
moisture will limit precip chances. A cold front drops into the
area Monday night and Tuesday, with more unsettled conditions
through mid week.
&&
.MARINE...
A weak boundary will lift across the Mid-Atlantic coast as
a warm front this evening. Expect mainly a SE wind of 5-10kt, with
the potential for localized stronger wind gusts in any tstms. Seas
tonight into Saturday will generally be 2-3ft, with a dominant
period of 6-8sec, and embedded swell with a period of 18-20sec.
High pressure settles off the Southeast coast tonight through the
weekend. This will result in predominate southerly flow late tonight
into Saturday, with sea-breeze aided SSE flow of 10-15kt is expected
Saturday aftn/early evening. The wind will veer back to SSW Saturday
night remaining aob 15kt. The pressure gradient tightens Sunday into
Monday ahead of an approaching cold front bringing the potential for
pre-frontal SCA conditions. This could boost a SSW wind to 15-25kt
for the Bay/ocean, 15-20kt for the Sound/Lower James, and ~15kt
elsewhere. Seas build to 3-5ft N of Cape Charles, and potentially 4-
6ft out near 20nm, with 2-3ft waves in the Bay. This cold front
approaches from the northwest Monday and gradually drops into the
coastal plain of SE VA and the Carolinas Monday night into Tuesday,
and then dissipated Tuesday night into Wednesday.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.
&&
$$
SYNOPSIS...SAM
NEAR TERM...MAS/SAM
SHORT TERM...SAM
LONG TERM...AJZ
AVIATION...SAM/JAO
MARINE...AJZ/MPR
Area Forecast Discussion
National Weather Service Albany NY
1049 PM EDT Fri Jun 16 2017
.SYNOPSIS...
Increasingly warm and humid weather along with the threat for
showers and thunderstorms through the weekend as a couple of low
pressure systems impact the region. Temperatures will rise above
normal by Fathers Day before a cold front approaches Sunday night
into Monday.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1045 pm...little change needed to going forecast. Previous
discussion follows.
As of 745 pm...area of showers has departed to the east, but
plenty of lower to mid-level moisture remains, so conditions
remain cloudy across the majority of the forecast area. We are
in a lull with respect to forcing, so have cut back on PoPs
through the overnight hours. A few showers may be possible for
portions of the Catskills, Mid-Hudson Valley, NW CT and the
Berkshires late tonight as the activity over Central PA attempts
to expand northeastward. This activity may be associated with a
very weak midlevel wave and enhanced midlevel theta-e. Have
included chance PoPs after around 06Z for this potential, but
hi-res models indicate anything should be rather light. With
moist low-levels fog could be a concern, but absent any breaks
in the clouds do not expect dense fog. Will continue to monitor
trends, however.
Showers continue to track east across the region with the
back edge of the precipitation extending across western New
England and the Taconics. Some additional convection has
developed well upstream of the region within the warmer air and
per satellite analysis, ample breaks in the overcast have
allowed for surface temperatures to climb well into the 70s
where SBCAPES per SPC mesoscale windows in excess of 2000 J/KG.
There remains some differences with respect to tonight`s
forecast as the NAM pushes through this frontal zone keeping the
region mainly dry, perhaps some pockets of drizzle and patchy
fog as low levels remain quite moist. The GFS and the latest
HRRR pick up on the notion of this frontal zone becoming quasi-
stationary as it becomes parallel to the upper flow therefore
stalling the forward progress. This allows for a wave to track
northeast for additional precipitation in the form of light rain
to develop across the southeastern 1/3rd of the CWA. We will
keep the chance PoPs for these areas through the overnight as we
watch trends unfold. Otherwise, a rather damp night for most of
the region as overnight lows range between 55-65F degrees.
Saturday a more noticeable increase in low level moisture as
dewpoints climb into the 60s. As for cloud coverage, a few
breaks are expected as instability parameters show a noticeable
increase across the region. Some scattered showers and
thunderstorms are possible across the area during the day as
SBCAPES climb between 1000-2000 J/KG yet hard to define any
definitive surface boundary. Perhaps differential heating and
terrain based convection may be able to develop hence the low
chance PoPs that remain in the forecast. Highs Saturday are
expected to bounce back into the mid 70s to mid 80s with dew
points on the rise it will feel like more 80s to near 90F.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
It will be muggy Saturday night with the region in the warm
sector with lows in the 60s. Sunday will be warmer and more
humid with dew points expected to rise into the upper 60s to
lower 70s with temperatures in the upper 70s to upper 80s. A
short wave rotating through the trough about the base of an
upper level low over Hudson`s Bay will pass to our northwest
during the day. The wind field across the region will increase
especially to the north and west of the Capital District. As for
potential instability, MLMUCAPES will increase to 1000-1500 J/KG
across most of the forecast area with 0-6 km bulk shear 30 to 45
kts across most of the area. The Day 3 Severe Thunderstorm
Outlook from the Storm Prediction Center has Slight and Marginal
risk across about the northwest 2/3 of the forecast area. Will
address threat in our Hazardous Weather Outlook along with
locally heavy downpours with high precipitable water values
across the area with PWs reaching 1.5 to 2 inches by Sunday
evening.
Chances for convection continue Sunday night as heights begin
to fall and the system`s cold front approaches western New York.
The threat for severe thunderstorms should wane with loss of
heating and a decrease in instability. Another muggy night is
expected with lows only into the 60s to lower 70s.
On Monday, a sharp upper level trough will be located over the
Great Lakes region, with a surface cold front slowly moving
eastward across New York State. This cold front will be running
into a strong ridge off the east coast, so it will be taking
its time as it crosses the area from west to east, with bands of
showers and thunderstorms. With a warm and very moist air mass
in place PWAT values may exceed 2 inches in some places, thus any
shower or t-storm will be capable of producing very heavy
downpours. We will need to watch for localized flooding if any
heavy rainfall repeatedly occurs over the same location. In
addition, there is still a chance of severe weather as MLMUCAPES
may rise over 2000 J/KG in places with 0-6 km bulk shear of 35
to 50+ kts possible. Highs on Monday will be in the mid 70s to
mid 80s.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The extended period will feature multiple threats for precipitation
with near normal temperatures.
After a cold front impacts our region during the day Monday, it
should shift into our far eastern CWA heading into Monday night so
have highest POPS in place in western New England with lower POPs
in our western CWA at the start of the extended period.
While the surface cold front will likely be east of the area by
Tuesday, a longwave trough will be entering into the Northeast and
the cyclonic flow could lead to diurnally driven scattered shower
threats on Tuesday (esp for the afternoon). Temperatures should not
be as warm as Monday falling back into the upper 70s/low 80s but
continued SW flow will keep dew points near 60.
Once we lose daylight, any scattered showers should diminish Tuesday
night. However, a shortwave embedded in the larger scale cyclonic
flow looks to swing into our CWA on Wednesday and bring with it yet
another threat for showers and perhaps some thunderstorms (again
best chance in the afternoon). Given the increased cloud coverage
and precip threat, high temperatures should be a bit cooler than
Tuesday with highs in the upper 60s for the elevations and upper
70s/near 80 elsewhere.
High pressure should build into the area on Thursday finally giving
us a break from the consecutive days of precipitation threats and
also usher in lower dew points in the upper 40s/low 50s; however,
this looks to only be a brief respite as another warm front appears
to arrive in the Thursday night/Friday period bringing a returned
threat for wet weather.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Despite the departure of showers, low-level moisture still
abounds this evening with MVFR/borderline-IFR cigs. Forecast
soundings and MOS suggest IFR potential at all sites as stratus
builds slightly lower. Low confidence with respect to timing,
but have included it earliest at KPOU due to possibly advancing
marine layer, and at KPSF due to their higher elevation. Low
dewpoint depressions and light winds will likely result in some
light fog as well, with some IFR vsby possible. Cannot rule out
patches of dense fog, but this appears conditional upon cloud
breaks developing, which does not appear likely at this time. A
few showers are possible at KPOU tonight as well, but unlikely
to have intensities that result in vsby restrictions below what
will already be seen in BR.
Conditions are expected to improve Saturday after daybreak as
the strong June sun angle promotes diurnal mixing. The
persistent light southerly flow may delay improvement at KPOU
until later in the morning or during the afternoon. A
thunderstorm or two cannot be ruled out as instability builds
tomorrow afternoon, but lack of forcing will greatly limit
coverage. Have kept previous forecast`s PROB30 mention for TSRA
during the afternoon.
Winds tonight will be light and variable. Southerly winds around
5 to 10 knots will develop Saturday by late morning into the
afternoon.
Outlook...
Saturday Night: Low Operational Impact. Slight Chance of SHRA...TSRA.
Sunday: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Monday: High Operational Impact. Definite SHRA...TSRA.
Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: Moderate Operational Impact. Chance of SHRA.
&&
.FIRE WEATHER...
Increasingly warm and humid weather along with the threat for
showers and thunderstorms through the weekend as a couple of low
pressure systems impact the region. Temperatures will rise above
normal by Fathers Day before a cold front approaches Sunday night
into Monday.
Relative humidity values will increase to near 100 percent
tonight, drop to 55 to 75 percent on Saturday, recover to 90 to
100 percent Saturday night, and drop to 55 to 80 percent on
Sunday.
Winds will be south at 5 to 10 mph this evening becoming light
and variable overnight, south at 5 to 10 mph on Saturday, light
and variable Saturday night, and south at 10 to 15 mph on
Sunday.
&&
.HYDROLOGY...
Our weather will be unsettled through at least early next week as a
couple of low pressure systems impact the region. Humidity
levels will be on the increase with high precipitable waters
values moving on Sunday into at least Monday. Storms will be
capable of producing locally heavy downpours which could lead to
some minor flooding of low lying and poor drainage areas.
Rainfall amounts will be variable and be dependent on where the
showers and thunderstorms occur although most if not all areas
will receive well over an inch of rain by early next week.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.EQUIPMENT...
KGFL airport observation continues to experience intermittent
communication issues.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...IAA/BGM/11
NEAR TERM...IAA/BGM/Thompson
SHORT TERM...IAA/11
LONG TERM...Speciale
AVIATION...Thompson
FIRE WEATHER...IAA/BGM/11
HYDROLOGY...IAA/BGM/11
EQUIPMENT...
Area Forecast Discussion
National Weather Service Gaylord MI
1145 PM EDT Fri Jun 16 2017
.UPDATE...
Issued at 1021 PM EDT Fri Jun 16 2017
Diurnally-driven convection that develop across mainly NE Lower
Michigan this afternoon/evening has greatly diminished and pushed
east of our CWA late this evening thanks to sunset. Our CWA
remains largely precip-free at this hour. However...a look at
upstream radars KGRB and KMQT shows another convective complex
working its way thru Wisconsin and Western Upper Michigan along
and inverted trough axis coincident with an instability axis
associated with low pressure centered over the Central Plains.
Short term models suggest a general diminish in intensity as this
convection pushes eastward into our CWA overnight. This seems
reasonable given a projected diminishing trend to instability and
850 mb theta E. This notion matches well with the latest Day 1
Outlook from SPC which now has all of Michigan in general thunder.
Have made some upward adjustments to POPs and timing of precip
into our CWA overnight based on latest observed and model data.
&&
.NEAR TERM...(Tonight through Saturday)
Issued at 357 PM EDT Fri Jun 16 2017
...Increasingly unsettled...
High impact weather potential...lingering thunderstorms into early
evening. Thunderstorms chances increasing again into Saturday.
Low pressure is slowly progressing across far northern Ontario, with
weak w to sw low-level flow into northern MI. Abundant surface
heating and lake breezes are contributing to deep convection, most
of which is in the expected locales (ne lower), but some of which is
not (near Elk Rapids earlier). With surface pressure lowering in
the Plains states, southwest low-level flow will increase into the
region. That is coincident with still relatively low 500mb
heights thanks to the closed 500mb low in northern Ontario, and an
occasional shortwave moving in from the west. This is an
increasingly favorable set-up for showers/storms.
Tonight...spotty convection will persist for several more hours,
especially in ne lower MI, and in western Chip/Mack (thanks to
upstream activity in central upper MI). Indications of small
hail/brief gusty winds with this activity, and a cell in ne Otsego
Co got close to svr levels, but didn`t quite get there. HRRR has
occasionally been arguing for activity in parts of WI to cross
Lake MI into nw lower MI, but that lake is still awfully cold for
surface-based convection to survive that trip. Will have some
small evening pops near Lake MI in response. Showers and a few
storms will increase from w to e overnight, as increasing sw flow
feeds elevated convection. Nothing svr expected for the nighttime
hours.
Min temps upper 50s to mid 60s.
Saturday...mid-level backs further wsw as a trof digs into the
northern Plains. That will further amplify low and mid-level
moisture transport northward. Ability to see substantial
destabilization this far north looks to hindered by significant
cloud cover, and the highest svr threat looks to be well-placed
downstate. However, we will be entering a better set-up for healthy
rainfall amounts as the day proceeds, with K indices pushing into
the mid 30s, and PWATs in excess of 1.5 inches (especially in the
se). Will attempt to portray some up-to-half inch QPF amounts in
afternoon, particularly near Saginaw Bay (with heavy rain threat
persisting into Sat night, see below). High likely pops in order in
most places - it will /not/ rain all day, but likely will at some
point.
Max temps mid 70s to around 80f.
&&
.SHORT TERM...(Saturday night through Monday)
Issued at 357 PM EDT Fri Jun 16 2017
...Thunderstorms possible Saturday night and Sunday, Showers
Monday...
High Impact Weather Potential...Marginal Severe risk into Saturday
evening.
Pattern Synopsis/Forecast...The sfc low and 500 mb shortwave trough
moves into the Upper Great Lakes and continues the thunderstorms
over the region into Sunday morning. Heavy rain is possible with the
system as the Pwat is between 1.00" and 1.5" by Sunday morning as
the 500 mb low rotates over Lake Superior. As the 500 mb shortwave
moves out of the region and the 500 mb low moves east of Lake
Superior a strong dry tongue moves into N lower and looks to stop
any rain and convection, until late in the day as the 850 mb
moisture moves back into the region with falling 850 mb
temperatures. This should produce self destruct sunshine, and
isolated to scattered showers. This will diminish into the evening
with the loss of day time heating. Monday as the 500 mb low
continues to rotate into the vicinity, it continues to cool the
region and more self-destruct sunshine develops along with scattered
showers.
Primary Forecast Concerns...Saturday afternoon/evening SPC has the
area of along and south of M-55, This looks like it would be the
best for the system as the 500 mb jet streak moves into the region,
with the RRQ of the jet over areas south of the forecast area. So
main concern is if the jet moves a little more north, and helps to
kick off more thunder, and possibly heavy. The other issue is heavy
rain...which is possible with the high pwat values and the decent
lift as the jet streak moves through.
.LONG TERM...(Monday night through Friday)
Issued at 357 PM EDT Fri Jun 16 2017
High impact weather potential...None.
A somewhat zonal flow pattern remains in place across the CONUS with
an anchoring long wave around 165W. Pattern is still expected to
become more amplified and "troughy" across the Great Lakes heading
through the weekend and the first half of next week as short wave
energy pushing through the PAC NW today dumps into the upper
Midwest/Great Lakes region late in the weekend. Pattern change will
accompany a fairly strong surface low and cold front that swings up
through the Great Lakes Saturday night/early Sunday...although
recent model runs have backed off on the strength of that system.
Following the weekend system...temperatures still look to take a dip
below normal for much of next week...particularly the first half of
the week as core of single digit 850 MB temps slide through. Daytime
instability showers also still a good bet through at least Tuesday.
Wednesday now holds promise for the best weather day of the week as
we get brief intervening surface high pressure moving through and
moderating temperatures. But then...another stronger weather system
will bring shower/thunderstorm chances back into the forecast to
finish up the work week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 1145 PM EDT Fri Jun 16 2017
Scattered to numerous showers and thunderstorms will develop from
west to east overnight...with good chances of convection continuing
on Saturday as an inverted trough slides thru Michigan. Overall
conditions will remain VFR thru the TAF forecast period...but may
briefly drop to MVFR within any heavier shower/storm activity.
Light/variable winds overnight will become SW AOB 10 kts on
Saturday.
&&
.MARINE...
Issued at 357 PM EDT Fri Jun 16 2017
Relatively light sw winds are expected into early Sat night, as
low pressure gradually transits far northern Ontario. Winds/waves
will remain below advisory criteria. Somewhat gustier west winds
Sunday as a cold front goes thru, but only an outside chance that
an advisory will be needed.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MLR
NEAR TERM...JZ
SHORT TERM...JSL
LONG TERM...TBA
AVIATION...MLR
MARINE...JZ
Area Forecast Discussion
National Weather Service La Crosse WI
650 PM CDT Fri Jun 16 2017
.SHORT TERM...(This evening through Saturday)
Issued at 235 PM CDT Fri Jun 16 2017
At 2 PM, a short wave trough moving through northwest Wisconsin
was producing scattered showers and storms across central and
northern Wisconsin. This system will move east across northern
Wisconsin and be located in western Upper Michigan by this
evening. As this occurs, a dry line will settle south toward the
Interstate 90 corridor. Dew points will be in the mid and upper
50s north of the dry line and in the lower and mid 60s south of
it.
As temperatures climb into the lower to mid 80s this afternoon,
the 0-1 km mean layer CAPES will climb into the 1500 to 2500 J/kg
range south of the Interstate 94. This CAPE will be building ahead
of an approaching short wave trough (currently located over
western Minnesota). The CAM models are in good agreement
thunderstorms will develop across east-central and south-central
Minnesota between 16.19z and 16.21z. The latest RAP suggest that
there will be sufficient deep shear that they will quickly develop
into supercell thunderstorms and then as their cold pools
coalesce the 0-3 km shear would favor a line of storms to move
through east and southeast through the area. The main severe
weather threat with these storms will be large hail and wind
through 16.23z, and then evolve into primarily a wind threat which
would last through 17.03z. While there is a severe weather threat
across the entire area, the greatest chance looks to be along and
south of the Interstate 90 corridor where the instability will be
the greatest.
For Saturday afternoon and night, a stronger short wave and
surface cold front will be moving through the region. Like the
past couple of days, the best instability will be well south of
our forecast area. However, there will still be 1000 to
2500 J/kg 0-1 km mean layer CAPE from northeast Iowa into
southwest and central Wisconsin. There may be sufficient deep
shear for a few supercell storms to develop. Both the HRRR and ARW
suggest this possibility. Meanwhile the NMM would suggest that
these storms would develop across east-central Iowa, northern
Illinois, and southeast Wisconsin. If this does occur, the primary
severe weather threats would be large hail and damaging winds.
There was a slight shift southward in the latest SPC Day 2
Outlook and this seems realistic.
.LONG TERM...(Sunday through Friday)
Issued at 235 PM CDT Fri Jun 16 2017
In the wake of this system, a much cooler air mass will move into
the region. 850 mb temperatures will fall into the 7 to 9C range
by Sunday afternoon and remain there for much of Monday. As a
result, high temperatures will only range from the upper 60s to
mid 70s. With 950 to 800 mb lapse rates over 8 C/km and 0-1 km
mean layer CAPES up to 1000 J/kg, scattered diurnally driven
afternoon and evening showers and thunderstorms will be possible
across much of the Upper Mississippi River Valley.
On Wednesday and Wednesday night, another short wave trough will
move through the region. While the GFS and ECMWF are still
differing on the amount of instability ahead of this system,
there looks to be sufficient shear for the potential of supercell
development. This system will have to watched over the next
several days.
From Thursday into Friday, the models hint at additional short
wave troughs moving along the US/Canadian border, but there has
been little consistency in the timing of these system. Due to
this, there is a broad brush of showers and thunderstorms chances
during this time period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 650 PM CDT Fri Jun 16 2017
Thunderstorms will continue at the TAF sites through early
evening. Expect large hail and wind gusts of 40 to 60 kts possible
in any severe storms. Also, anticipate IFR conditions in any
steadier rains or storms. The strongest storms will push east of
the TAF sites by late evening.
&&
.CLIMATE...
Issued at 235 PM CDT Fri Jun 16 2017
The first half of June was the warmest at both La Crosse WI and
Rochester MN.
Through the first half of June, the average temperature at
La Crosse Regional Airport was 75.3 degrees. This was 8.3 degrees
warmer than the 1981-2010 average and the warmest first half of
the June. The previous record was 73.3 degrees in 2005. Records
date back to 1873.
Meanwhile during this same time period, the average temperature
at Rochester International Airport was 72.5 degrees. This was 7.1
degrees warmer than the 1981-2010 average and the warmest first
half of the June. The previous record was 71.1 degrees in 1956.
Records date back to 1886.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Boyne
LONG TERM...Boyne
AVIATION...Wetenkamp
CLIMATE...Boyne
Area Forecast Discussion
National Weather Service Duluth MN
1053 PM CDT Fri Jun 16 2017
.UPDATE...
Issued at 1053 PM CDT Fri Jun 16 2017
Showers and a few thunderstorms continued across portions of the
Northland, with the stronger showers/storms occurring over
northern Wisconsin. A low level boundary and low level FGEN continues
to focus additional development over northwest Wisconsin and we
have adjusted POPs through the evening to account for the latest
radar trends. Much of the guidance is in agreement that overall
the coverage of the showers/storms will diminish overnight then
increase through the day Saturday.
UPDATE Issued at 653 PM CDT Fri Jun 16 2017
Please see the 00Z Aviation Discussion below.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 330 PM CDT Fri Jun 16 2017
A closed upper low over northwest Ontario will drift around this
same area this afternoon through Saturday. Embedded vorticity maxes
in the fast flow aloft will move over the forecast area through
Saturday. A longer wave trof will extend from the upper low
southwest into South Dakota by Saturday afternoon. This leads to
periodic episodes of showers and isolated to scattered
thunderstorms for late this afternoon through Saturday. First
group of showers and storms was forming along a surface boundary
from north of McGregor through southern Bayfield county to Hurley,
WI, which shows up nicely on KDLH radar. Additional showers were
beginning to pop along the Borderland. Virtually no CAPE along
the international border, so expect showers only. These pieces of
energy and their resultant shower and thunderstorm activity will
be difficult to time, although the HRRR has been doing a decent
job. Followed the HRRR and blend of other convective allowing
models for the rest of the afternoon and tonight. Min temps will
be in the 50s. The best opportunity for more widespread showers
and storms will be on Saturday. This is when a long wave trof will
cross into the Dakotas by the afternoon. A more vigorous shot of
vorticity moves into the base of the trof and will generate a more
generous area of showers and storms by afternoon across the
region. There will be some showers in the morning, especially
north of U.S. Highway 2 in northeast Minnesota. With more cloud
cover anticipated, max temps will be a bit cooler with upper 60s
along the Borderland, to the upper 70s over the southern tier of
the region.
.LONG TERM...(Saturday night through Friday)
Issued at 330 PM CDT Fri Jun 16 2017
Our upper low pressure system for tonight and Friday exits off
quickly to the east Friday night and Saturday, allowing a ridge of
high pressure to build into the area for Saturday night. This
leaves us with some potential for below freezing temperatures for
both Friday night and Saturday night. Have concerns for cloud cover
and wind both nights which could keep frost from forming or keep
temperatures a little too warm, but the potential is there and we
will need to reevaluate again tomorrow. Saturday looks cool and
mostly cloudy.
Sunday our next weather system takes shape over southern
Saskatchewan and moves east across Canada, pulling some warmer
temperatures into the area for both Sunday and Monday and our
frost/freeze concerns diminish for both days.
Monday night through Tuesday night we have another upper level wave
moving across the area, which interacts with a decent baroclinic
zone lying over the forecast area. This should bring another round
of precipitation to the area, with rain south and either a rain/snow
mix or all snow north.
Wednesday we have another ridge building into the area with enough
cold air to give us more potential for frost/freeze concerns.
Thursday and Thursday night the models are hinting at another wave
moving across the Midwest which should bring us some rainfall, but
there are some pretty significant differences in the models this far
out and have kept pops low for now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 653 PM CDT Fri Jun 16 2017
VFR through the TAF period, however there may be some periods
where MVFR ceilings/visibility develops if a shower/storm passes
through a terminal. Cyclonic flow will continue across the Upper
Midwest with a cutoff low rotating across Ontario. The combination
of the cyclonic flow and diurnal heating has brought scattered
showers and storms. Expect this activity to diminish once the
sun sets. Have held off in including any thunder mention at TAFs
this evening, as SPC mesoanalysis has MLCAPE off to the south, but
think the best chance of a thunderstorm this evening would be at
KHYR. Think there is a low chance of fog development at
HIB/INL/BRD, but suspect there will be too much cloud cover for
good radiational cooling.
A trough will dig into the Northern Plains on Saturday. This
combined with heating will result in scattered showers and storms
developing across the region per the latest guidance. Uncertain
on how widespread thunderstorm activity will be at this point, so
have left in as VCSH.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 54 73 52 65 / 50 70 60 40
INL 51 68 50 60 / 40 60 40 40
BRD 55 76 53 65 / 60 70 60 20
HYR 56 78 55 66 / 60 70 70 50
ASX 55 76 52 66 / 50 70 70 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
UPDATE...Melde
SHORT TERM...GSF
LONG TERM...LE
AVIATION...WL
Area Forecast Discussion
National Weather Service Sioux Falls SD
630 PM CDT Fri Jun 16 2017
.SHORT TERM...(This evening through Saturday)
Issued at 239 PM CDT Fri Jun 16 2017
Main forecast concerns are the potential for severe weather late
this afternoon and evening and then the larger area of rain on
Saturday.
For this afternoon, the severe weather threat appears to confined
south of Hwy 18 in Iowa as well as far southeast South Dakota and
northeast Nebraska. There is a strong jet streak moving into eastern
South Dakota this afternoon and this will interact with a convergence
line across north central Nebraska to initiate convection. 0-6 km
shear profiles are very favorable for the development of supercells
with 0-6 km bulk shear from 40 to 50 kts. The limiting factor is
moisture. Dew points over northeastern Nebraska are in the upper 50s
and lower 60s. With southerly flow, this drier air will advect
northeast into northwestern Iowa this afternoon behind accas that
developed late this morning. There is deeper moisture south of I80
where GOES-16 imagery shows PWs approaching 1.5 inches and surface
dew points near 70 degrees. There is high confidence convection will
develop across northeastern Nebraska. However, supercell motion will
be southeast and any storms developing near O`Neill should remain
south of Sioux City and Wakefield. The question is if there will be
additional development north of the NE/SD border as the boundary
moves toward Sioux City and if enough moisture will exist to support
strong updrafts. At this time, do expect at least a few storms to
develop - perhaps as far north as Hwy 18 near the IA/SD. However,
the limited moisture is expected to keep to most storms from
becoming severe with the greatest risk being a microburst with winds
up to 60 mph due to the evaporative cooling within the dry boundary
layer. If enough moisture can get into the Sioux City area by late
afternoon, then supercells capable of producing 2+" hail will be
possible. However, current trends in dew points as well as HRRR
indicate that this threat is low.
Convection should move east of the area prior to midnight tonight. A
strong will wave will approach from the northern Rockies late
tonight and Saturday. Instability is rather limited due to limited
moisture and much cooler temperatures. However, this wave will have
a lot of ascent associated with it. Therefore begin to increase the
chance of showers and thunderstorms by late tonight and spreading
into southwest Minnesota and northwestern Iowa by early Saturday
afternoon. There is just enough instability to keep thunder in the
forecast and expect that many areas north of I-90 will see at least
light rain. With the limited moisture generally expect rainfall
amounts to be less than 0.25". Evaporative cooling and cloud cover
will result in highs 10 to 20 degrees cooler than today - generally
be in the 70s with coolest readings in southwestern Minnesota.
.LONG TERM...(Saturday night through Friday)
Issued at 239 PM CDT Fri Jun 16 2017
Should see precipitation wane through the evening Saturday night, as
upper trough and associated cool front exit to our east. In the wake
of this system, cool air will briefly settle into the region Sunday,
with highs only in the 70s for most areas. The cooler air lingers
across the northeast into Monday, as the upper trough swings slowly
east through the Great Lakes, while a building upper ridge over the
Rockies begins to bring warmer air back into southwest parts of the
region. Various weak waves slide across the region through this
upper trough, bringing light precipitation chances to the Northern
Plains Sunday, and to a lesser degree again Monday afternoon.
A northern stream wave crosses the Canadian Rockies and flattens the
ridge through the middle of next week, which brings a transition to
quasi-zonal flow across the northern CONUS through the upcoming work
week. Vast differences among the models regarding the strength of
this initial wave, and thus in their depiction of how far south into
the Canadian Prairies/far northern CONUS it will dig by mid to late
week. Stronger solutions bring another push of cooler/more stable
air into the region by Thursday, while weaker solutions maintain
near to above normal temperatures and greater instability. With the
uncertainty in solutions at this range, did not alter broad model
blend for pops or temperatures at this point. However, did limit
thunder potential to just slight chance/isolated range, with the
exception of Wednesday when there is better consensus in the models
allowing instability to build ahead of the wave.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 623 PM CDT Fri Jun 16 2017
Will linger a VCTS group for the KSUX TAF site for one hour,
ending it at 01Z as the TSRA complex continues to move toward the
southeast. There will be some isolated to scattered TSRA in
northwest IA through perhaps 01Z to 02Z, but that activity will
likely not be severe at this point and will not affect the KSUX
TAF site. Otherwise, VFR should be the primary category through
the TAF period, with some scattered TSRA activity possible on
Saturday over KFSD and KHON as an upper air disturbance and cold
front swing through. Any TSRA activity on Saturday will likely not
be very strong.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...Schumacher
LONG TERM...JH
AVIATION...MJ
Area Forecast Discussion
National Weather Service Lincoln IL
913 PM CDT Fri Jun 16 2017
.UPDATE...
Issued at 913 PM CDT Fri Jun 16 2017
Made some adjustments to the forecast grids for the overnight time
period to slightly increase PoPs. Radar mosaics and Clean IR loop
showing several clusters of storms/MCSs from southern WI to
central IA and southeast NE. The MCS in southwest IA and NE has a
definite southeastward propagation to it, while the weaker cluster
of storms in northern IA is moving more eastward.
Many of the convective allowing models, are bringing at least a
portion of the convection into central Illinois. The HRRR, and to
a lesser extent the 00z NAM, are indicating showers and a few
thunderstorms pushing into the IL River Valley around 3 am. After
that time the convection scatters out more and weakens. Thus, went
with likely PoPs for the IL River valley and 30-50 PoPs in the
rest of central and eastern IL. Parts of southeast IL may stay
rain free overnight, with any lingering showers holding off until
Saturday morning.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 313 PM CDT Fri Jun 16 2017
Partly cloudy afternoon today going into a rather stormy start to
the weekend. Some cu out there, but so far convective activity
has been limited for the bulk of Central IL. Some showers and
thunderstorms over the southern portions of the state along the
Mississippi River Valley, but otherwise quiet for the afternoon.
Expected scattered development of some convection later this
afternoon in the east. Weak pops continuing through the evening
hours, increasing after midnight, particularly in the NW.
Overnight convection will receive an assist by the LLJ ramping up
ahead of the next system. Wave of energy rippling through the
region tomorrow as well as warm advection will assist in a general
lifting of the airmass and scattered showers and thunderstorms
will be possible throughout the day. However, the chances will
increase into the afternoon/evening hours as a front draws closer
to the NW.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 313 PM CDT Fri Jun 16 2017
Details for the frontal passage tomorrow night are difficult to
come by as the models are still having issue with the speed of the
system, as well as the volume of convection during the day
providing a wrench to instability parameters later in the evening.
As a whole, the forecast remains much the same...hot and muggy
until a frontal passage late Saturday night brings a different
airmass into the Midwest.
A weakened area of low pressure has remained over south central
Canada for several days now. Early Saturday an impulse moves on
the Pac NW coast, rippling into the region and digging back in
over the northern Plains and Upper Midwest, resulting in a more
amplified flow pattern. Associated surface
system develops over the Northern Plains and becomes better
defined as it moves into the Great Lakes region, dragging a cold
front behind it for Saturday night. Uncertainty still clouds how
deep the system, the time of arrival, as well as the impact of
prefrontal showers and thunderstorms for the afternoon that would
impact the development of the evening storms along the boundary.
Should the heat of the day remain largely untouched through the
day on Saturday, the convective potential will lend itself to some
severe storm development tomorrow night, with some decent sheer
into the midlevels. SPC has left much of Central IL in an Enhanced
Risk as a result.
Temperatures at 850mb drop a few degrees for a slightly cooler
wrap up to the weekend and beginning of next week. Behind Sat
night/ Sun morning storms, models dry out and cool off
briefly...at least until midweek. At the end of the forecast,
significant WAA pattern setting up in the midlevels resulting in a
warm up and return of pops for midweek.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 650 PM CDT Fri Jun 16 2017
Isolated convection is expected in east and southeast Illinois
early this evening, but far enough away from any of the TAF sites
to mention VCTS.
Will be watching the convective systems blossoming into western
Iowa for the potential to slide ESE into central Illinois late
tonight. The short range convective allowing models don`t have the
best handle on this, although the HRRR does show the remnants of
an MCS moving into central IL in the 07-11z time frame. For now
will mention VCTS in the TAFS after 07z and through daybreak, but
with VFR ceilings.
VFR conditions will prevail through much of Saturday. However,
with a tightening gradient and decent mixing will increase the
winds and add gusts at most location from late morning through the
afternoon.
Kind of tough to time the movement of t-storms toward the TAF
sites late in the afternoon due to the movement of a weak front
from the west and associated upper level forcing/shear. The best
bet is after 22-23z, so will introduce at least VCTS at the TAF
sites along and west of I-55.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Miller
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...Miller
Area Forecast Discussion
National Weather Service Indianapolis IN
657 PM EDT Fri Jun 16 2017
.UPDATE...
The Near Term and Aviation sections have been updated.
&&
.SYNOPSIS...
Issued at 327 PM EDT Fri Jun 16 2017
High pressure ridge over the southeast U.S. will retreat to the
east. Low pressure moving into the central plains will track
across the upper midwest and Great lakes over the weekend. A
cold front will push across Indiana by Sunday. Dry and slightly
cooler weather will occur early next week after the weekend. But
warmer weather and a chance of more storms will return by the middle
of next week.
&&
.NEAR TERM /Tonight and Saturday/...
Issued at 657 PM EDT Fri Jun 16 2017
Based on latest HRRR runs and ongoing convective development, have
brought the slight chance of thunder down into Indy metro for a
few hours this evening. Storms appear to be forming on a weak
convergence zone but are significantly diurnal in nature, which
will limit their persistence into the overnight. Previous
discussion follows.
Issued at 327 PM EDT Fri Jun 16 2017
Radar indicated scattered thunderstorms across the middle
Mississippi valley...southern great lakes and and south central Ohio.
Models and water vapor satellite indicate a weak upper disturbance
will move east across northern Indiana early this evening. Air mass
over central Indiana has been capped and nothing has developed in
our area so far. The rapid refresh model indicates there could be
an isolated thunderstorm over northern and far western sections
early this evening...then mostly dry weather will occur overnight
with perhaps a slight chance of more storms reaching western
sections towards daybreak. Will keep areas from INDY and to the
southeast dry overnight with slight chance POPS north and west early
this evening and slight chance POPS mainly west again late tonight.
On Saturday there will go with chance POPS most areas by afternoon
as another weather disturbance moves our way along with a bit more
moisture. Lows tonight will be in the upper 60s to near 70 and
highs Saturday will be in the middle 80s to around 90 which is close
to a MOS blend.
&&
.SHORT TERM / Saturday night through Monday/...
Issued at 327 PM EDT Fri Jun 16 2017
Forecast challenges focus on storm chances Saturday night into
Sunday as a very warm and unstable airmass will occur ahead of a
cold front approaching from the northwest.
Models indicate two waves of convection with one moving our way and
weakening late Saturday and then a stronger one moving our way
Saturday night. Air mass will be quite unstable with MU capes in
excess of 2000 J/KG and models hint at a possible MCS Saturday
night. Will go with likely POPS over northern sections and high
chance POPS elsewhere Saturday night.
Sunday could be wet as well as a cold front moves through our way.
Will go with likely POPS south and chance POPS elsewhere Sunday with
storms ending from the northwest late Sunday.
Other than a slight chance of storms south Sunday evening...mostly
dry and cooler weather will occur Sunday night and Sunday as high
pressure behind the cold front builds east. The blended MOS gives
20 percent POPS far northeast late Monday...but all in all expect
dry and cooler weather to the the rule.
Stayed close to a MOS blend on temperatures most periods with lows
in the lower 70s Saturday night and lower 60s Sunday night. Highs
will be in the lower 80s Sunday and upper 70s to near 80 Monday.
&&
.LONG TERM /Monday night through Friday/...
Issued at 225 PM EDT Fri Jun 16 2017
Dry weather will start the long term for Monday night in the wake
of a frontal passage. Then there will be only small or slight
chances for thunderstorms until Wednesday night while broad high
pressure is in place from the Plains through the Ohio Valley. From
Wednesday night on better chances for thunderstorms will arrive as
the upper pattern flattens out and a a couple of surface system
approach and move through the area. Temperatures will climb by a
degree or two each day, with highs reaching the middle 80s to
around 90 by Friday and low Friday morning getting back into the
upper 60s to lower 70s.
&&
.AVIATION /Discussion for the 17/00Z TAFs/...
Issued at 657 PM EDT Fri Jun 16 2017
VFR through the period outside of potential convective impacts.
Widely scattered storms this evening will impact LAF and may
briefly impact HUF/IND. Impacts are too uncertain for explicit
mention, but may include brief forays into MVFR territory if
convective cores move over the airfields.
Otherwise, patchy light fog will be possible tonight where rain
falls but unlikely to have significant impacts.
Somewhat more widespread convection is possible very late in the
period, but again, too uncertain for much more than vicinity
mention.
Winds will be around 10KT or below throughout the period,
generally out of the south.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/NIELD
SHORT TERM...JH
LONG TERM...CP
AVIATION...JH/NIELD
Area Forecast Discussion
National Weather Service Northern Indiana
656 PM EDT Fri Jun 16 2017
.SYNOPSIS...
Issued at 336 PM EDT Fri Jun 16 2017
Showers and thunderstorms will remain possible prior to the
passage of a cold front on Sunday. The best chance for organized
thunderstorms, including the risk for severe weather, is Saturday
night into early Sunday. Lows will be in the 60s tonight with
temperatures warming back into the middle 80s Saturday.
&&
.SHORT TERM...(This Evening through Saturday)
Issued at 336 PM EDT Fri Jun 16 2017
Second of 2 MCV`s working across the area, sparking little more
than a few showers at this time. As it works into eastern areas
can`t rule out a rumble of thunder as it encounters a narrow axis
of better instability. Behind the area, satellite would tend to
suggest a good deal of subsidence. However, SPC meso data shows at
least some instability still lingering back in portions of
Illinois where temps have recovered into the middle 80s and
dewpoints were slightly higher. Vis sat showing a few cu starting
to pop which could indicate some isol shower/storm development
could edge in towards evening as advertised by a handful of CAMS
as a weak disturbance noted on water vapor edges in. Not
comfortable dropping pops entirely so leaning towards 20 to 30
pops through 03Z then a lull until later tonight when remnants of
upstream convection may be arriving, which brings a set of
challenges all it`s own for Saturday.
CAMS showing several scenarios with upstream convection, any of
which are plausible ranging from a dying area of showers and storms
approaching overnight into early Saturday to showers and storms
diving southwest of us along what may be best instability and
moisture gradient. As a result have kept highest pops NW late
tonight into Sat AM with more changes likely to come as complex
evolves to the west. Going into Sat afternoon, should be at least
some clearing in the wake of morning activity that will allow
destabilization across the area. Forcing mechanisms may exist in the
form of leftover outflow boundaries or even a MCV that could impact
the area during the afternoon, which could bring isol to sct storms.
Confidence low in how this will unfold so have opted to broadbrush
pops in mid chance range for the afternoon. Focus on greatest severe
threat will be into long term period.
&&
.LONG TERM...(Saturday Night through Friday)
Issued at 336 PM EDT Fri Jun 16 2017
Threat for severe weather still looms with only subtle changes to
SWODY2 with Enhanced risk now bumping up against our western
counties. For the time being, think this was a good move as
several factors still remain in question for severe threat,
including those mentioned in short term discussion.
Have generally held with likely pops much of Saturday night given
gambit of solutions in terms of timing, possibly as early as 3Z to
as late as 7Z for arrival in the west. Main mode of severe should be
damaging winds, which could be on the stronger side if well
established cold pool and forward propagation of the line hold
together which is normally a challenge into the less favorable
convective window of the overnight hours. However, as eluded to in
past discussion dynamics and potential organization may very well
negate these issues. For more details on the mesoscale setup, refer
to DY2 outlook which matches close with thinking here.
Otherwise, cold front will sweep through by Sunday with cooler and
less humid air arriving through mid week. Warm front will begin to
edge back north for the second half of the week, slowly increasing
both temps and humidity. No major system, but arrival of warm front
could bring some precip chances as well as hit or miss convection
south of it into the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 651 PM EDT Fri Jun 16 2017
Main concern this taf cycle is TS potential. Sct TS forming along
east-west boundary extending from east central IL into west
central OH early this eve. Some newd drift of these cells is fcst
by latest HRRR suggesting they could impact FWA before diminishing
with loss of heating later this eve, though questionable if
sufficient instability farther ne to sustain storms, thus, just
planning to mention VCTS til 02z in FWA taf. S-SW flow will
strengthen overnight as a convectively enhanced shrtwv moves into
the mid MS valley. This should destabilize airmass across nrn IN
and allow ongoing storms over nrn IA/srn MN to track se across nrn
IN Sat morning. Airmass across our area will grdly destabilize
again in wake of morning convection Sat, but lack of sgfnt
forcing supports leaving TS out of fcst for the aftn, though an
isolated storm psbl. Outside of TS, VFR conditions expected
through the period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...Fisher
SHORT TERM...Fisher
LONG TERM...Fisher
AVIATION...JT
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Area Forecast Discussion
National Weather Service Jackson MS
921 PM CDT Fri Jun 16 2017
.DISCUSSION...
A very impressive mesoscale convective vortex is driving a severe
bow echo rapidly southward through southern portions of the
ArkLaMiss late this evening and have extended the severe
thunderstorm watch in time to account for this. The HRRR has had
trouble keeping up with the accelerated convective evolution with
previous runs showing the MCV would maintain convergent
boundaries and additional storm development through much of the
night...but the latest trends are for complete overturning of the
airmass and less chance for renewed convection late tonight on the
back side of the system. Have tried to reflect latest trends in
this forecast update...but rain chances for after midnight are of
lower confidence given inconsistencies in guidance. In any case,
expect the threat for severe storms to end with passage of the
current bowing line. Will just need to watch for any renewed
convection and locally heavy rain potential...especially on the
upstream side of system due to very heavy rain that fell earlier
today. /EC/
&&
.AVIATION...
00Z TAF discussion:
The threat for SHRA/TSRA will linger well into the night as extra
lift associated with a disturbance helps to maintain convection
beyond sunset and this will keep the threat for IFR category
ceilings/vsby relatively high at most sites. Outside of the
SHRA/TSRA, expect mainly VFR conditions with some potential for
early morning fog. Additional storms could redevelop for locations
mainly east of the GWO/JAN corridor Saturday afternoon. /EC/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 70 91 74 91 / 85 26 14 13
Meridian 69 90 74 91 / 84 28 17 24
Vicksburg 74 92 74 91 / 57 23 12 9
Hattiesburg 71 90 72 91 / 85 26 16 27
Natchez 73 90 73 90 / 63 21 11 16
Greenville 69 91 75 91 / 48 20 10 10
Greenwood 69 91 75 90 / 70 23 12 12
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
Area Forecast Discussion
National Weather Service Jacksonville FL
931 PM EDT Fri Jun 16 2017
.UPDATE...
Overall things have settled down this evening with just a few
showers popping up over the interior areas this evening. The HRRR
model is interesting as it is bringing a boundary across the
Suwannee Valley overnight with a few showers and possibly an
isolated thunderstorm popping up between midnight and sunrise. the
line moves from the Suwannee River and Madison County near
midnight to Trenton and Macclenny by sunrise. Otherwise a humid
summer night in store for the area with some light fog near
sunrise where the heavier rain fell today.
&&
.AVIATION...
looking at VFR conditions at all fields overnight with a scattered
deck developing between 1300-1500 utc tomorrow.
&&
.MARINE...
the Bermuda Ridge axis will remain southeast of the region through
Saturday. This will keep a south to southwest flow across the
areas with a southeasterly sea breeze developing during the
afternoon and evening from the seabreeze. Surface ridge will lift
north across the waters Sunday into early next week produce a
south to southeast flow. Winds will be slightly stronger during
the afternoon and evening hours due to the seabreeze but winds
area expected to remain below headline criteria. Seas generally
less than 4 feet. Scattered showers and thunderstorms.
Rip Currents: A low end moderate risk along the northeast Fl beaches
through Saturday due to a long period swell. Risk may become
enhanced early next week as flow will tend to become more south to
southeast.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 71 92 73 92 / 40 30 30 20
SSI 75 88 77 86 / 30 30 30 20
JAX 72 91 74 90 / 40 40 30 40
SGJ 72 89 74 86 / 40 30 30 40
GNV 71 91 72 91 / 30 40 20 50
OCF 71 90 73 90 / 20 40 20 60
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Sandrik/Shuler/Corless
Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
1000 PM CDT Fri Jun 16 2017
.UPDATE...
Updated grids and forecast package to carry thunderstorms a little
deeper into the overnight hours and to mention gusty winds with
thunderstorms as MCS continues to move southward across central
Mississippi. Storms are about to enter northern portions of the
area, but reflectivity levels have dropped quite a bit in the last
30 minutes. HRRR and RAP were indicating quick weakening, but
won`t let down our guard quite yet. 35
&&
.PREV DISCUSSION... /issued 500 PM CDT Fri Jun 16 2017/
SHORT TERM...
A complex of storms has developed across northern and central
Mississippi this afternoon in association with a small vorticity
maximum in the NNW flow aloft. Short term guidance indicates the
storms will continue to the Gulf Coast this evening, primarily
from 0 to 5Z this evening and generally across eastern portions of
the area. The storms are expected to weaken through the evening,
but will still be advancing through an environment with about 2000
J/KG mixed layer CAPE. The primary threat would be strong
downbursts within some of the storms though hail is still possible
as well. Closer to the coast there is probably still a more
stable layer around 800 mb, which will aid in the eventual
weakening of the storms.
Overall high pressure across the region this weekend will keep
rain chances after tonight low, though diurnal scattered showers
and storms will still be possible with the sea and lake breeze.
Temperatures will be a bit warmer with daytime highs near 90.
LONG TERM...
Early next week the central Gulf Coast will be in between the
strong ridge anchored over the desert southwest and the western
edge of the Bermuda high to the east. Well to the south a tropical
low pressure is likely to develop near the Yucatan, which is the
feature currently being monitored in Tropical Weather Outlooks.
This surface low will develop only gradually the next several
days, with no rapid strengthening expected. By Tuesday this broad
low pressure will be in the south central Gulf. The upper level
pattern over the Gulf allows for a wide range of track
possibilities next week due to the lack of strong steering flow
and the weak nature of the low, which is represented by the spread
in guidance. At the moment general westward movement toward south
Texas or the northern portion of the Mexican coast seems most
plausible. Movement too far to the northwest into the ridge is
unrealistic. The development and track of the tropical feature
will continue to be monitored for potential impacts the central
Gulf Coast. For example, if the low drifts further into the
central Gulf an increase in moisture and rain chances would be
possible for south LA and MS later next week.
Krautmann
AVIATION...
VFR conditions are expected to prevail through this evening. The
main concern and uncertainties are with regards to TSRA threats and
timing. Greatest confidence where scattered or greater coverage of
TSRA occurs is at KMCB this evening, so included a TEMPO group. Did
not include mention of TS in the remaining TAFS at this time, but
that may need to be added later as development trends become better
defined. MVFR CIGS should return after 08-09z tonight through 14-15z
Saturday mainly at KBTR, KHDC and KMCB. Isolated to locally
scattered TSRA are expected again mainly in the afternoon on
Saturday, so later TAF issuances may need to add mention. 22/TD
MARINE...
A broad area of high pressure system will remain centered to the
east of the coastal waters through the weekend resulting in
generally light winds and seas with the exception of in and near
thunderstorms and associated outflow boundaries. An area of low
pressure is expected to move into the southern Gulf of Mexico early
next week. Refer to the latest Tropical Weather Outlook from the
National Hurricane Center for additional details.
At this time, the model blends used brings easterly winds up to near
15 knots or slightly higher over southern waters by late Monday
through Wednesday morning before veering to southeast near 15 knots
over most coastal waters Wednesday afternoon. Wave heights will be
dependent on how fast and how strong either a tropical wave or
cyclone develops along with the size and distribution of the wind
field. Current forecast brings wave heights up to 6 to 7 feet late
Monday into Tuesday, but all aspects of the forecast are likely to
change with future developments in the lower Gulf. 22/TD
DECISION SUPPORT...
DSS CODE...Blue.
DEPLOYED...None.
ACTIVATION...None.
ACTIVITIES...Monitoring river flooding.
DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED = FULL ENGAGEMENT FOR MODERATE TONIGHT RISK SVR
AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
SIGNIFICANCE
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 71 91 73 90 / 60 30 10 20
BTR 74 90 75 91 / 40 20 10 20
ASD 75 90 75 89 / 60 30 20 30
MSY 75 89 75 89 / 50 30 20 30
GPT 76 88 77 87 / 60 30 20 30
PQL 74 88 75 87 / 60 40 20 30
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Louisville KY
746 PM EDT Fri Jun 16 2017
.Forecast Update...
Issued at 740 PM EDT Fri Jun 16 2017
Made some minor adjustments to fog grids this evening through
tomorrow morning based on latest model data. Latest trends seem to
indicate that the fog potential may not be as high as previously
thought, mainly due to dry air aloft and increasing southwesterly
winds around 1kft that could potentially mix down to the surface.
Best chances for patchy fog still look to generally south and east
of the Bluegrass Parkway.
Still planning on keeping the forecast dry for the evening, though
am closely monitoring some small potential for very isolated
showers/storms in northwestern portions of the CWA in southern
Indiana. Some isolated showers and thunderstorms have begun firing
off near the KVWX radar within the past hour or so and are slowly
drifting toward Dubois/Perry counties. Several outflow boundaries
are being picked up by radar/satellite as well. A quick mesoanalysis
of the environment reveals 1500-2000 J/Kg MUCAPE across portions of
southern Indiana, however, capping is quite strong and should keep a
lid on most convective activity. If the isolated activity holds
together, it should arrive into Dubois/Perry counties shortly after
02z. Will continue to monitor and update the forecast if it appears
activity will hold together into the late evening hours.
&&
.Short Term...(This evening through Saturday night)
Issued at 230 PM EDT Fri Jun 16 2017
Latest preliminary GOES-16 derived precipitable water indicates a
narrow swatch of dry air over the region, stretching from central
Tennessee into Central Kentucky and then northeast to western New
York. This area is not moving much today, and AMDAR and current RAP
soundings show a subsident airmass in place across much of the
region. Thus have generally fair weather cumulus forming out there.
Temperatures are warm under the good insolation, with dewpoints in
the upper 60s to around 70, so the day is not overly perfect, but
typical for mid June. Only other concern then would be chances for
fog overnight.
A look at the GFS flow aloft indicates a weak disturbance moving
through the Midwest to our north tomorrow afternoon, and then
another one approaching the region late Saturday night. Precipitable
water is expected to increase between now and Saturday night as more
moist air pushes against our dry plume. Usually the edges of these
dry plumes are where convection gets fired during daytime heating,
so the current forecast for isolated to widely scattered pops across
southern Indiana seems reasonable, with just isolated chances along
the I-65 corridor. Warm temperatures should go for that mostly dry
forecast, with highs Saturday reaching the 90s for many locations.
Saturday night, the hi-res models, and to a lesser extent the
coarser ones, bring in a decaying line of storms ahead of a cold
front late. So here again will keep in the higher rain chances over
the northwest, southern Indiana, with a gradient into south central
Kentucky. Night time lows will depend on how quickly, or if,
showers/cold pool get into the region.
.Long Term...(Sunday through Friday)
Issued at 230 PM EDT Fri Jun 16 2017
The timing of precip Sunday will depend greatly on when/if rains
move through here Saturday night. Long-wave troughing aloft will
provide some energy for new development, with cold mid-level lapse
rates. Any boundary from the late Saturday night development could
serve as a focus as well for new development during the afternoon.
As for severe risk, the wind profile shows more shear potential than
with the last few days worth of convection, especially over the
northern half of the area. Temperatures for highs here again will
depend on location of these boundaries.
One other thing to note, precipitable waters from the models look
awfully high, especially given that the GFS/NAM/GEM all would argue
for record values for mid June. Still expect at least above average
moisture into the region, so heavy rainfall will come with any
storms that fall.
By Monday, most of the precip should be just over or east of
central Kentucky, with the trough axis aloft swinging through here
and ridging trying to build in for midweek. Models have been
struggling with bringing in (or not) a frontal boundary and rains
Tue night/Wed and then beyond that we are back to a series of
disturbances moving through the flow making timing best rain
chances difficult this far out. Will keep up with the slight
chances for Wednesday and limit peak rain chances the rest of the
work week to that 20-30 percent range.
Monday should be the coolest day of the extended, and then we`ll
flip back to above normal by mid week, though again they will depend
on what should happen with that midweek system.
&&
.Aviation...(00Z TAF Issuance)
Issued at 700 PM EDT Fri Jun 16 2017
Latest guidance beginning to back off on fog development near the
LEX/BWG terminals tomorrow morning due to drier air aloft and 10-
15kt southwesterly winds 1kft above the surface with the potential
that some of it could mix down. Not completely sold that they will
remain fog free tomorrow morning, so will at least include a TEMPO
group for MVFR visibilities tomorrow morning.
Otherwise, expect some strato-cu to redevelop across the region
tomorrow morning and afternoon. Expect most of it to be in the VFR
range, but could see some high-end MVFR cigs near BWG briefly
tomorrow morning.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...DM
Short Term...RJS
Long Term...RJS
Aviation...DM
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
846 PM CDT Fri Jun 16 2017
.UPDATE...
846 PM CDT
Near term focus remains on thunderstorm development and trends
overnight. While low levels will slowly stabilize after sunset,
forcing from approaching mid-level disturbance and strengthening
mid-upper level westerly wind fields may continue to support
the potential for a few strong/severe storms into northwest and
north central IL through the late evening/early overnight hours.
SPC has expanded the current day 1 slight severe risk into the
northwest part of the cwa with the 01Z update.
Region radar depicts a fairly large area of convection currently
occurring across western Wisconsin, with evidence of an MCV
northwest of Madison. High-res CAM`s have indicated the potential
for southeastward development into northwest IL since this
afternoon, and while 00Z DVN sounding supports RAP initialized
mesoanalysis data with 2300 J/Kg MUCAPES, there has been a lack of
cumulus development since this afternoon east/south of the
could/rain shield which has entered northwest IL with the MCV.
Recent HRRR runs (00Z particularly) seems to be catching on, and
focuses additional development across eastern/northeastern Iowa
over the next few hours where warm advection ascent ahead of mid-
level short wave over western IA and trailing flank of the WI MCV
circulation is already beginning to initiate storms west of
Waterloo. Expectation is that these storms will fill in towards
northeast IA, and eventually move into northwestern IL by
midnight. Greatest potential for strong/severe storms will be
across our far west/northwest cwa where higher MUCAPES exist, with
a gradual weakening expected overnight as storms spread farther
east. Main threats would be winds where cold pool consolidation
occurs or mesoscale rear inflow develops, with the strongest cores
perhaps capable of producing marginally severe hail. Remnant MCS
rains may linger into early Saturday morning especially across
eastern parts of the cwa, with lingering cloud cover and
subsidence behind the system initially stabilizing the
atmosphere for the morning hours.
Ratzer
&&
.SHORT TERM...
125 PM CDT
In The Near Term...
Forecast confidence on timing of individual shortwaves and better
periods of thunder in the near term is not super high, but there
will likely again be several periods of generally weakening
showers and embedded thunder. The first shortwave in fast moving
flow aloft is currently across southern MN and moving into WI and
will just have some clouds, with showers north of our area. The
next more organized wave across the Dakotas and into Nebraska will
interact with an increasingly unstable airmass and likely lead to
a complex of showers and storms late this afternoon and evening.
Guidance is mixed as to how much of this first area will impact
the area, but the northern half of the area stands the chance of
another round of showers and embedded thunderstorms.
KMD
Tonight Through Saturday Night...
Continue to closely monitor the potential for severe weather
across the area/region on Saturday, especially Saturday evening,
which could include a higher end wind and hail threat.
Thunderstorms appearing to be highly probable throughout the day
Saturday into Saturday night area wide. This includes a period of
thunderstorms possible Saturday morning, scattered development
possible by mid/late afternoon, and then more widespread and
strongest thunderstorms by the evening. Once again, this includes
the entire area. However, varying guidance continues to bounce
around with exactly how the day will unfold. This includes some
uncertainties regarding each period of possible thunderstorms,
with which the Saturday morning development could have an impact
on instability and development later in the day. Surface pattern
appearing really messing during the day Saturday, likely from
guidance trying to resolve this deep convection produced from this
large/strong system expected to move through region. So, at this
point will stay focused on a more synoptic scale approach and what
makes sense conceptually given what latest guidance is depicting.
Early in the period, zonal flow in place will likely continue to
usher in upstream short wave energy over the central CONUS. A
likely scenario from this support would be for continued
thunderstorm development over the northern Plains late this
evening, with these thunderstorms then likely following
instability axis into northern Illinois by late tonight but more
so early morning Saturday. What more than likely will happen will
be what occurred last night with thunderstorms moving into our
area but on a diminishing trend. However, forcing appears to be
stronger which could support more widespread coverage and with
instability also slightly higher, these thunderstorms may have a
chance to stay stronger. These thunderstorms and potential
strong/severe threat of mainly hail with a low threat of wind
could linger through mid morning, before departing to the east.
Setup would then favor clearing skies with sunny conditions then
supporting a destabilizing atmosphere into the afternoon. There
doesn`t appear to be strong support for any widespread
thunderstorms by midday or early afternoon. However, could see
possibly needing to monitor for isolated development during this
time though, on any lingering outflow boundaries. This could be
especially the case by mid/late afternoon as multiple pieces of
guidance depicting some isolated development. Confidence is low on
exact placement, but anything which were to develop could pose a
severe/hail threat. Most locations will likely be dry for most of
the afternoon though, with the more widespread development not
arriving until the evening hours.
By late afternoon into the early evening, large scale ascent
really ramps up across the region. This is in response to digging
upper level trough with strong upper jet moving overhead, and with
increasing mid level energy and flow. This increase in upper
level flow, which will include flow at 500mb approaching 70KT or
higher, will support bulk layer shear quickly ramping up by early
evening to more than enough values supportive of organized
development. Attendant surface low expected to quickly deepen
during this time, with overall setup then favoring an increase in
thunderstorms. This is as most guidance is in agreement with
moderate/strong instability to be in place during this time.
However, situation gets really complicated, with low confidence
still in place for placement of this low and general surface
pattern. Increase in coverage likely during this time/evening,
with main development expected to be in and around surface low and
associated boundaries. Once again, confidence as to where this
main development will occur is low at this time. This is key as do
think initial thunderstorms will have the potential to be
discrete, with the quickly increasing wind fields. Soon there
after, setup would then favor a transition over to more linear
convection. A wind threat, quite possibly higher end, would then
be the more probable hazard in the evening. Given the extent of
the potential instability, large hail will also be possible, along
with heavy rainfall and localized flooding.
With low confidence as to the surface pattern and initiation,
don`t want to really put any focus on any one area across the CWA.
At this time, these hazards appear possible across the entire
area. The threat of storms and these hazards could continue
through late in the evening and quite possibly into a portion of
the overnight hours, before exiting the area. Area depicted by
SPC`s SWODY2 including the elevated risk area still appears valid
given the potential setup and also the uncertainty. After whatever
precip develops and then evolves tonight into early Saturday
morning, a more refined threat area including the main threats
should hopefully be realized.
Rodriguez
&&
.LONG TERM...
138 PM CDT
Saturday night through Thursday...
Following the frontal passage Saturday night, a cooler and drier
airmass will settle into the region. The upper level low
responsible for the active weather will remain parked across south
central Ontario for several days. This will lead periods of clouds
and showers in the cyclonic/northwest flow around the southern
periphery of the low across northeast Illinois and northwest
Indiana. A more organized wave on the back side of the low will
move through on Tuesday as the low ejects to the north and east
which could give the showers a bit more kick and also lead to some
thunderstorms in the northwest flow pattern.
Mid week there will be a transition period as the low moves east.
Low level flow will turn southerly and advect a steadily warmer
and more moist airmass northward as the upper level jet shifts
north. An active zonal jet stream will bring additional shortwave
energy toward the region leading to additional thunderstorm
chances in the later Wednesday/early Thursday time frame.
KMD
&&
.AVIATION...
For the 00Z TAFs...
627 pm...Main forecast concern is thunderstorm potential late
this evening through sunrise Saturday and again late Saturday
afternoon into Saturday evening.
Area of convection along the MN/IA border is moving generally east
with weaker showers/convection extending south. Short term
guidance suggests this activity may begin to build southeast over
the next few hours following a better instability axis into far
northern IL. Confidence this will occur is only medium but added
tempo thunder for this potential later this evening. If this does
occur...an outflow boundary is likely to produce gusty northwest
winds. A second area of convection developing over eastern NE is
expected to move southeasterly this evening with new development
to the northeast that will likely arrive in a weakening phase
during the predawn hours. Its possible this activity may end up
prevailing showers with some embedded thunder but confidence
regarding its weakening is low. Opted to include tempo thunder
around sunrise for this potential.
A cold front will move across the area Saturday night and
thunderstorms are expected to develop ahead of this cold front
late Saturday afternoon and quickly spread across the terminals
Saturday evening. Confidence for thunderstorms during this time
period is high but coverage remains uncertain with perhaps
scattered coverage across the terminals and a more solid line
south of the terminals. Still a bit early for specifics but
thunder mention late in the afternoon at rfd and during the 24-30
hour period of the ord taf is reasonable with this forecast but
changes to timing/coverage is possible with later forecasts.
South/southwest winds will diminish under 10kt with sunset and
remain southerly overnight. Convection may allow winds to turn
more southeast or easterly at times overnight. Winds will turn
back south/southwest by mid/late Saturday morning and forecast
soundings would suggest gusts in the 20-25kt range are possible
Saturday afternoon. cms
&&
.MARINE...
138 PM CDT
Several periods of thunderstorms overnight tonight into early
Saturday and again Saturday evening will likely lead to periods of
occasionally stronger winds over the lake and nearshore then
depicted in the text forecasts, with potentially damaging winds
during the Saturday night time frame. Those with outdoor
recreation plans on the lake should stay abreast of severe
thunderstorm forecast for later Saturday and Saturday night. Also
of note, thunderstorms last night kicked up waves to 3 ft or so in
the nearshore zones with outflow ahead of and with the storms.
Similar storms may occur in the early morning Saturday time
frame.
Low pressure over Ontario will move to James Bay early
Sunday morning. Southwest to south winds 10-20 kt continue
through Saturday. A secondary low pressure trough dips south over
the western Great Lakes Saturday night while strengthening into
Sunday as it moves northeast into Ontario. Winds become westerly
to 25 kt on Sunday behind the low. High pressure will build over
the plains early this week and spread over the Ohio Valley Monday
night/Tuesday. A high pressure ridge will pass over the western
Great Lakes Wednesday and winds become southerly (to 25 kt or so) behind
it Wednesday night/Thursday ahead of another modest low that will
move into the Great Lakes region.
KMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Omaha/Valley NE
804 PM CDT Fri Jun 16 2017
.MESOSCALE DISCUSSION...
Issued at 747 PM CDT Fri Jun 16 2017
Supercell storms have congealed into an outflow dominant line.
Intense winds have occurred with the storms over the western part
of the Omaha metro area. Winds at WFO Valley gusted to 88 mph at
736 PM CDT. Storms are going to continue driving south-southeast
at 40 mph. Storms are following gradient of the downdraft CAPEs
around 1200 J/KG. Storms will continue producing wind damage as
they drive southeast in easteren Nebraska. Leading edge of storms
should reach a Nebraska City-Shenandoah, IA line around 840 PM
CDT.
In addition, QCLS tornadoes are possible on the leading edge of
the line of storms as they move southeast.
&&
.SHORT TERM...(Tonight through Monday)
Issued at 336 PM CDT Fri Jun 16 2017
Severe thunderstorm threat through this evening remains the primary
forecast concern.
Atmosphere was taking its time recovering this afternoon from
Thursday evening convection, however the process was slowly
occurring. Mid level shortwave as shown by enhanced water vapor
imagery was progressing into central Nebraska at mid afternoon,
ushered along by 90kt upper level jet knifing into the western
Dakotas. Surface front was sharpening in central Nebraska as well,
with 60-70F dew points streaming north ahead of it into south
central Nebraska. 850 moisture was also slowly increasing in this
area as per RAP analysis, noted by 12C dew point temp just ahead of
surface front. Northward extent of moisture return was less than
previous model solutions, but HRRR continued to initiate
convection in north central Nebraska, and that has occurred as of
330 PM.
As convection moves across northeast Nebraska as per HRRR,
strongest activity is likely to develop/move southeast with time
this afternoon and evening into plume of higher moisture and
instability across south central and southeast Nebraska. However
high effective bulk shear is in place now and will continue across
all of eastern Nebraska into southwest Iowa through the evening.
Thus even where instability is somewhat lacking, severe storms are
still possible.
While hail is likely with any storms given combination of shear and
instability, wind threat is also enhanced where inverted-v soundings
are prevalent in our north, and cold pool acceleration in the south.
There is a tornado risk as well, especially with initial development
of storms over the southern half of the state where low level
moisture is in place, and also as supercellular structures maintain
themselves as scattered line progresses southeast and interact with
mesoscale surface boundaries.
Expect line of storms to progress south and east of our area late
this evening, leaving most of the rest of the night dry. Another
stronger mid level trough is still forecast to drop into the Dakotas
Saturday, enhancing lift over cooler air behind surface front. Thus
scattered showers are possible during much of the day in our north.
To the south, most model output suggests cold front and thus surface
instability will be well to our south during the afternoon. However
there is plenty of spread suggesting southeast Nebraska and
southwest Iowa may be close enough for strong storms during
afternoon heating. A slight to enhanced risk is outlined by SPC Day
2 outlook there, but will have to see how far front progresses
before getting overly concerned.
Otherwise cooler conditions are forecast Saturday and Sunday when
northerly low level flow keeps highs in the 70s to lower 80s. Highs
rebound back into the lower 80s on Monday when westerly low level
flow brings slightly warmer air into the region.
.LONG TERM...(Monday night through Friday)
Issued at 336 PM CDT Fri Jun 16 2017
Northwesterly mid level flow will begin the longer term period, with
a gradual return to a more zonal pattern by the end of the week. No
major storm system are forecast to affect our area during this time,
so precipitation chances will be confined to impulses rolling
through the faster mid level flow. Timing of these features is
impossible to pin down this far out, and model output offers varying
opinions on timing and magnitude. Suffice it to say there will be at
least random chances for convection beginning Tuesday night and
continuing through Friday. Temperatures are likely to rebound back
into the upper 80s to lower 90s most spots Tuesday through Thursday,
and perhaps a bit cooler on Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 628 PM CDT Fri Jun 16 2017
Line of convection in northeast Nebraska will affect the KOMA TAF
site between 01Z and 04Z with IFR conditions and will have the
potential for wind gusts over 50kt and large hail. Storms will
likely just skirt KLNK area, but could produce similar
IFR/wind/hail between 02Z and 04Z. Storms are south of KOFK and
will remain that way. North winds will overtake all TAF sites
later tonight and will continue into Saturday with mainly mid and
high level clouds.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
MESOSCALE...Smith
SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...Dergan
Area Forecast Discussion
National Weather Service Blacksburg VA
735 PM EDT Fri Jun 16 2017
.SYNOPSIS...
High pressure offshore will maintain a warm and humid airmass
across the region into this weekend. A weak cold front will
approach the area from the northwest this weekend with added
showers and storms likely into early next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 710 PM EDT Friday...
Mesoanalysis at 23z showing high pwats in place and slow moving
cells. Despite lack of deep convection, the precip rates are
higher than indicated by radar, and given slow movement are
causing some isolated low lying and street flooding issues.
There is a decent theta-e ridge/converge zone from the NC
foothills into SE WV. Short range models especially the latest
HRRR hang onto this activity in the same general area through
late evening. At the same time, convection in the NC piedmont is
expected to send enough of an outflow to develop showers/storms
over southern VA/northern NC by 03z, as forecast by the HRRR.
Attm, favoring a demise of showers in the west as sun goes down,
but think higher pops are more likely over the piedmont to
foothills this evening.
Given how coverage of showers/storms are, not organized enough
to have any flash flood watches out. However, with high pwats,
any slow moving storms, especially over urban areas will likely
cause street flooding.
Previous afternoon discussion...
Radar continue to show scattered showers/thunderstorms with
locally heavy rain. satellite imagery has shown extensive cloud
cover most of the day and this has helped limit instability.
While the environment remains marginally conducive for severe
storms with modest CAPE values and weak shear supporting an
opportunity for gusty winds, the main threat will be local
flooding from storms with high rainfall rates that cluster/train
over the same locations. While latest meso guidance is showing
an opportunity for a resurgence of convection early tonight,
will shade POPs toward a consensus and monitor closely. Expect
some patchy fog again overnight, then another round of diurnal
convection tomorrow as we remain in a warm, moist, and unstable
airmass with broad synoptic ascent and weak shortwave energy
streaming through a trof to our west.
Temperatures will remain near seasonal norms with highs
tomorrow generally in the low/mid 80s east of the Ridge, upper
70s/lower 80s west.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 310 PM EDT Friday...
Subtropical plume of moisture will remain along the east coast
through Monday. Strong upper trough and associated cold front will
approach from the northwest Sunday and slowly cross the forecast
area Monday. Squeeze-play between the cold front and lingering
tropical plume will promote scattered to numerous showers/storms
Sunday and numerous to widespread showers/storms Monday. Greatest
threat from this sort of weather scenario is heavy rainfall, with
high rain rates (3-5 inch an hour) which could easily result in
actual amounts of 1-3 inches. Combination of strong diurnal heating
ahead of the front and increasing upper level dynamics from the
upper trough will also support the risk for severe weather,
increasing winds aloft supporting organized deep convection with the
potential for damaging winds.
Temperatures and dewpoints through this period of the forecast will
remain quite summerlike with humid/muggy conditions both day and
night, temperatures in the 80s to near 90 for highs and 60s for
lows.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 310 PM EDT Friday...
The connection to the tropics is forecast to be interrupted Tuesday
into Wednesday as a strong upper trough moves from the Great Lakes
and into New England, clipping the Mid-Atlantic. This troughing
should induce enough west to northwest wind aloft to suppress the
deeper subtropical moisture to our southeast, helping to lower the
overall PWAT. There is still some question as to whether we will
have enough drying to totally suppress the threat for an afternoon
shower/storm, but at the very least we should have more sun than
clouds for mid-week with most of the CWA favoring the dry side of
the forecast. Not until we get deeper moisture to return ahead of
an approaching front toward the end of the week do pops
substantially go back up. As such think this period of the forecast
will be relatively rain free with forecast temperatures near normal
for Tue/Wed...the trending 4 to 8 degrees above normal Thur/Fri. .
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 712 PM EDT Friday...
We will see variable aviation conditions this evening and per
High-res models appears better threat for convection will be
toward Danville. As of this writing, BLF seems to be in line to
have heavier showers and sub-VFR cigs/vsbys through 02z.
With weak frontal boundary from Southern WV to Southside Va per
sfc theta-e analysis focus stays in place through early
overnight, especially east of the mountains.
Will not get fancy with showers/storms and have VCTS or VCSH
with tempo group early for DAN/ROA/BLF.
Overnight is the cig/vsby issue and expect some low cigs/vsbys
in this moist environment. Question is how low. Wx pattern
suggest for more stratus than fog, so will hit LIFR cigs at all
TAF sites. Fog will be around, especially higher ridges, and
possibly LWB/BCB but overall IFR to MVFR vsby.
Any fog/stratus will slowly dissipate Saturday morning and we
will repeat the cycle of diurnal convection. Outside of
thunderstroms winds will generally be light through the period.
Extended Aviation Discussion...
Very moist and unstable conditions combine with an approaching
trof to keep convective activity, with a strong diurnal trend,
in the forecast into the weekend. There will also be a trend fog
fog/stratus development during the predawn hours. A better
chance for more widespread showers and storms including sub-VFR
looks to arrive on Monday with a surface cold front perhaps
crossing the region. This will allow for extended periods of
sub- VFR ceilings and visibilities. In addition, radiational
late night/early morning fog will be on the increase.
Appears will see drier conditions Tuesday/Wednesday but not
completely free from a chance for showers.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH/MBS
NEAR TERM...MBS/WP
SHORT TERM...PM
LONG TERM...PM
AVIATION...JH/MBS/WP
Area Forecast Discussion
National Weather Service Shreveport LA
940 PM CDT Fri Jun 16 2017
.UPDATE...
Only minor changes made to the ongoing forecast. Ongoing
convection east of the forecast area has promoted cirrus blow-off
to move across portions of southwest AR and northern LA, thus
causing an update to the Sky grid. Elected to drop POPs to below
mentionable levels across the northeastern zones a few hours
earlier than expected tonight, given the aforementioned convection
has been maintained east of the ARKLATEX. Otherwise, forecast is
largely on track with another rather mild overnight /middle to
upper 70s/ followed by another slightly above normal day tomorrow.
&&
.PREV DISCUSSION... /issued 648 PM CDT Fri Jun 16 2017/
AVIATION...
Vfr conditions areawide with s-sw winds 5 to 10 kts. Mvfr cloud
decks to arrive into ne TX in low lvl sw flow by around 17/12z,
and then quickly diminish with daytime mixing by 17/15-16z with
mostly vfr skc as upper ridge increases over area. S-sw winds
around 10 kts Sat aftn with a few higher gusts over mainly ne
TX./07/
PREV DISCUSSION... /issued 226 PM CDT Fri Jun 16 2017/
DISCUSSION...
Convection for the most part has developed just as expected with
the more favorable storm track staying just northeast and east of
our CWA where a weak disturbance in northwest flow is interacting
with strong instability. Upper ridge is suppressing any thought
of convection across the remainder of our region attm. Did keep
slight chance pops going across our extreme northeast and eastern
zones as a descent cu field was observed in afternoon VIS loop in
the wake of the disturbance but even the more advantageous HRRR
has now shifted late afternoon/early evening convection to our
east before convection weakens with the loss of heating and
instability. Not seeing much in the way of upstream disturbances
embedded in northwest flow aloft as has been the case the last
couple nights that could effect us late tonight or during the day
Saturday so with a strengthening upper level ridge axis across our
region, kept pops out of the forecast for Saturday. What will be
on the uptick so to speak will be afternoon Heat Index values
which will be just under Heat Advisory Criteria for portions of
our region. The same will be true for Sunday but we reintroduce
pops for late Sunday and especially Sunday Night into Monday along
and ahead of an unseasonably strong cold front.
Longwave trough will become rather stagnant to our south and east
and should not influence our weather too much for Sunday but a
digging upper level trough across the middle portions of the
country will drag along with it a cold front which will begin
knocking on Southeast Oklahoma`s door late Sunday Aftn and will be
the trigger necessary for scattered late afternoon and especially
evening convection. Upper level support does not warrant a
widespread severe weather threat with this convection but cannot
rule out an isolated strong to severe thunderstorm across
Southeast Oklahoma or Southwest Arkansas Sunday Evening. The front
will very slowly make its way towards the I-20 Corridor of
Northeast Texas and Northern Louisiana by mid to late morning on
Monday again with scattered convection possible along the
boundary. The drier/milder air will lag the sfc boundary somewhat
Monday Night but should begin to filter into our entire area
during the day Tuesday with drier dewpoints and lower humidity
values. We will continue to undercut blended model temperatures
concerning overnight lows through much of next week given the
drier post frontal airmass conditions. Needless to say, pops are
near nil beyond Monday of next week but low level moisture should
return quickly by late next week into next weekend and along with
the moisture return will be a return to isolated to scattered
convection.
Thanks for the coordination today FWD...JAN...prelims to
follow...13.
PREV DISCUSSION... /issued 1145 AM CDT Fri Jun 16 2017/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 76 93 76 93 / 10 10 10 10
MLU 75 93 75 93 / 10 10 10 10
DEQ 72 94 75 89 / 10 10 10 30
TXK 75 93 76 91 / 10 10 10 20
ELD 74 93 75 91 / 10 10 10 10
TYR 76 94 76 93 / 10 10 10 10
GGG 76 93 76 93 / 10 10 10 10
LFK 74 94 76 94 / 10 10 10 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
29/07/13
Area Forecast Discussion
National Weather Service Tallahassee FL
920 PM EDT Fri Jun 16 2017
.NEAR TERM [Through Tonight]...
This evening`s mesoanalysis showed the nearest organized
convective cold pool along the AL-MS border. The latest HRRR runs
initialized this feature well, and do not have it reaching our
forecast area overnight. The MCS that moved through our forecast
area last night really turned the troposphere over, leaving a
warm, relatively dry pocket at around 925 mb and switching the
lower tropospheric flow to a NW direction. This combination has
significantly limited deep moist convection today as the NW sea
breeze front got pinned at the coast for much of the afternoon. It
was finally propagating inland this evening, but only a few
storms have been able to develop in the marginal thermodynamics.
This trend will continue through the morning.
&&
.PREV DISCUSSION [740 PM EDT]...
.SHORT TERM [Saturday Through Sunday Night]...
Both the 00z ECMWF and 12z GFS are in fairly good agreement
through early Sunday showing an elongated trough through the
Central Gulf. Thereafter, their solutions diverge with the EURO
showing the trough deamplifying with the Bermuda ridge and ridge
over Texas bridging across the northern Gulf. The GFS shows the
trough persisting through the short term and into the extended
period. Both solutions would have a sharp contrast of impacts on
our forecast due the prescience of a tropical disturbance over the
northwest Caribbean Sea over the weekend. The building upper
ridge would steer the system west or northwestward and well away
from our CWA. The GFS shows a surface low along with a surge of
tropical moisture lifting northward across the eastern Gulf late
Sunday and Sunday night. Until then we should see less convection
over the Tri-state region both Saturday and Sunday due to the
influx drier air in the mid levels with forecast PW`s down around
1.4-1.5". Temps will be near seasonal levels.
.LONG TERM [Monday Through Friday]...
A lot of uncertainty in the extended forecast per above discussion
on model differences. For now will lean toward the ECMWF solution
which takes the tropical disturbance over the Yucatan Peninsula
and across the Bay of Campeche through the week. Thus, for now
expect a typical summertime pattern with diurnal convection with
PoPs generally in the 30-50% range. Highs in the upper 80s to
around 90 with lows in the 70s.
.AVIATION [Through 00Z Sunday]...
VFR conditions are expected to prevail through the majority of the
period at all terminals. One exception could be around sunrise at
TLH as winds become light/calm, and patchy fog could develop along
with some scattered low clouds. Any fog will be short-lived during
this time, and after it dissipates scattered clouds with light
southwesterly winds are expected to prevail through the remainder
of the period.
.MARINE...
Favorable marine conditions expected with light winds and low
seas through Sunday night. Beginning Monday, winds and seas will
increase to more moderate levels as a tropical disturbance moves
into the southern or Gulf of Mexico.
.FIRE WEATHER...
No concerns.
.HYDROLOGY...
Scattered afternoon showers and thunderstorms are expected for the next
several days. Rainfall accumulations will generally be around 1-2
inches through Sunday, but isolated areas could receive that in a
single afternoon. Due to the scattered nature of the storms,
widespread river flooding is not expected, however, isolated
flooding will be possible.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 71 89 69 89 71 / 10 40 20 30 20
Panama City 76 85 75 85 75 / 20 30 20 20 20
Dothan 72 90 73 89 72 / 20 40 20 30 20
Albany 72 90 72 90 73 / 10 30 20 30 20
Valdosta 72 89 72 90 73 / 20 40 20 30 20
Cross City 73 88 71 90 73 / 20 40 10 20 40
Apalachicola 76 85 74 85 76 / 10 30 10 20 30
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Fournier
SHORT TERM...Barry
LONG TERM...Barry
AVIATION...Lahr
MARINE...Barry
FIRE WEATHER...Fournier
HYDROLOGY...Moore