Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/29/17
Area Forecast Discussion
National Weather Service Bismarck ND
948 PM CDT Wed Jun 28 2017
.UPDATE...
Issued at 945 PM CDT Wed Jun 28 2017
Have confined shower chance to extreme southwest North Dakota and
dropped pops to less than 20. Really, sprinkles at best.
There is a batch of showers and storms crossing the south-central
part of Saskatchewan, moving east. Will expect these to weaken as
they move into drier low level air with no CAPE and no surface
support for convergence to keep them going. Have opted NOT to add
pops to the Canadian Border counties.
Final issue is the possibility of fog in the James River Valley.
Patchy fog is possible, but not likely. More likely formation is
east of Jamestown where more rain fell last night and this
morning. Will NOT add patchy fog at this point.
UPDATE Issued at 715 PM CDT Wed Jun 28 2017
Will be updating the weather forecast grids to completely remove
the risk of thunder for this evening. Storms in eastern Montana
continue to weaken as they move into dry low level air and an area
where there is no CAPE or surface convergence to sustain them.
Will keep the increased chances southwest for the very late
night / toward daybreak.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 145 PM CDT Wed Jun 28 2017
The regional weather for the rest of the work week will focus on
an upper level low over western Canada forecast to move into the
Northern Plains. This will set the stage for increasing chances
for scattered showers and isolated thunderstorms. However limited
available moisture will keep rainfall to scattered light amounts.
A weak h500 shortwave trough moving through Montana with an
associated surface low is currently supporting scattered showers
and isolated thunderstorms across eastern Montana. These may
diminish somewhat after peak heating and as they move into western
North Dakota as depicted by the HRRR this evening.
A better scenario for showers and scattered thunderstorms will
form Thursday as a lobe of vorticity moves into the region. The
Superblend guidance gives 30 to 50 POPs across the region
although once again precipitation amounts will be hit and miss and
generally light.
.LONG TERM...(Thursday night through Wednesday)
Issued at 145 PM CDT Wed Jun 28 2017
The extended forecast will initially be impacted by the cool h500
upper low over the Northern Plains Friday. However Global models
are trending toward a broad warm and dry ridging pattern which
will herald warm and dry weather for the start of July. Scattered
showers and isolated thunderstorms associated with the upper low
will exit the region on Friday, and will be followed by a long
and steady warming trend. Highs Friday will be in the 60s and
lower 70s. By early next week and the Fourth of July highs will be
well into the 80s to lower and even mid 90s. No significant
precipitation is expected.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 945 PM CDT Wed Jun 28 2017
VFR weather through the TAF valid period. A series of middle
level atmospheric waves will approach starting after 291000Z
associated with a mid level trough. There is surface support for
the system in the form of a surface trough and cold front. Expect
Scattered -SHRA and Isolated TSRA at KISN and KDIK after 291500Z,
spreading east.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JPM
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...JPM
Area Forecast Discussion
National Weather Service Caribou ME
908 PM EDT Wed Jun 28 2017
.SYNOPSIS...
An unsettled weather pattern will persist through the weekend.
This will keep the threat of showers and thunderstorms across
the region through the upcoming weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
9:08 PM Update...Showers continue to dissipate across the CWA
this evening. As of 9 PM there is only one shower on radar in
northern Hancock and a small portion of western Washington
County. Mainly clear to partly cloudy for the next several
hours outside of that one isolated shower. Looking upstream on
satellite and radar there are clouds and showers in Quebec
associated with a shortwave moving toward the area, and the near
term models such as the HRRR and RAP indicate that a few
showers could work into western portions of the CWA after
midnight. Made some minor tweaks to the forecast based on the
current observations, satellite and radar, and near term models
and model trends.
Previous discussion...
Afternoon showers and thunderstorms will quickly diminish by
early evening as an upper level disturbance moves east of the
region. Expect partial clearing this evening before clouds once
again are on the increase in advance of the next short wave
approaching from the northwest. There could also be patchy fog
late tonight. Lows will range from around 50 across the north
and the mid 50s central and down east.
Another upper disturbance is poised to cross the region on
Thursday with more showers expected. With a bit less in the way
of SB Cape expected on Thursday, have only included isolated
thunderstorms for Thursday afternoon. Highs on on Thursday are
expected to range from the low 70s across the north and mid 70s
across central and downeast. It will be a bit cooler along teh
coast.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Models cont to advertise our fcst area straddling the
baroclinic zone between cooler canadian air to our N and much
warmer, moister tropical air to the S of the Rgn thru the short
term. In the meantime, a series of s/wvs cont to move W to E
across the Rgn from Cntrl Can alg this frontal blyr. this will
result in bouts of shwrs and tstms.
The first bout will occur later Thu ngt into erly Fri morn and
will msly affect Cntrl and Srn ptns of the FA. A second round
is then slated to affect our Rgn Later Fri into Fri ngt. with a
3rd then xpctd later Sat. Considering that even ngt tm shwrs
will likely have enough elevated CAPE for thunder, we did not
distinguish between diurnal/nocturnal tstm preference, instead
using chc tstms with possible hvy rn with likely and abv shwr
PoPs and isold with chc shwr PoPs. With increasingly higher PWs
going into the weekend, the risk of hvy rnfl and possible
flooding increases spcly by later Sat aftn into Sat ngt and
spcly Cntrl ptns of the Rgn, where PWs once again reach into
the 1.75 to 2.00 range. Attm, we went conservative with 6 hrly
QPFs Sat aftn and eve given uncertainty regarding where banding
of shwrs and tstms will occur exactly ovr our FA. We will alert
subsequent fcst shifts about the possibility of needing of
flood watches for ptns of our Rgn in later fcst updates.
Temps will slowly warm thru the short range, with most warming
occurring with ovrngt lows.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
The potential of shwrs and sct tstms with lcly hvy rnfl will
cont into the late ngt across all of Rgn as a warm occlusion
advcs ENE thru the area. Following this front, shwrs and tstms
should decrease in cvrg on Sun, being more diurnally driven in
the late aftn as the cntr of the high PW stream moves E of the
FA. One last upper trof crosses the Rgn from QB on Mon with
additional shwrs and perhaps isold tstms with a slight cooling
trend. Tue and most of the Rgn on Wed would then be much drier
with regard to any shwrs/tstms with somewhat less humid
conditions with at or slightly abv avg hi temps.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
NEAR TERM: Expect mainly VFR early this evening outside of any
lingering showers and brief MFVR conditions. Patchy fog to
develop tonight with lcl MVFR/IFR conditions, but confidence was
not high enough to include in the 00Z tafs. MVFR is once again
expected in scattered showers and isolated thunderstorms.
SHORT TO LONG TERM: Mainly hi MVFR and low VFR by day in shwrs
and isold to sct tstms with ngt tm fog lowering clgs and vsbys
at ngt to IFR to LIFR alg with shwrs/tstms all TAF sites from
Fri thru Sun ngt with msly VFR Mon.
&&
.MARINE...
NEAR TERM: The wind/seas are expected to remain below small
craft advisory levels through Thursday.
SHORT TO LONG TERM: Wv hts will be nearly SCA thresholds Fri
thru Sun then gradually subside sig below 5 ft erly next week.
Went with about 75 to 95 percent of WW3 guidance for fcst wv hts
with wv pds msly in the 5 to 7 sec range. Another concern will
be the increasing presence of marine fog as we head into the
weekend as increasingly more moist tropical flow of air from
trop Atlc streams Nwrd ovr the Gulf of ME.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...CB/Duda
Short Term...VJN
Long Term...VJN
Aviation...CB/Duda/VJN
Marine...CB/Duda/VJN
Area Forecast Discussion
National Weather Service Dodge City KS
1005 PM CDT Wed Jun 28 2017
...UPDATE TO SYNOPSIS...
.SYNOPSIS...
Issued at 1002 PM CDT Wed Jun 28 2017
WV imagery indicates a zonal flow aloft prevailing across the Western
High Plains. Meanwhile, an upper level trough of low pressure is
digging southeast across the Northern Rockies. Near the surface, an
area of low pressure is anchored across southeast Colorado with an
attendant frontal boundary extending northeast across western Kansas
into southeast Nebraska.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 320 PM CDT Wed Jun 28 2017
Mid afternoon surface map and clear-air radar returns showed a
frontal zone across southwest KS from roughly Liberal to near Dodge
City to near Hays. This front had pretty much stalled out with
afternoon heating. Mid level temperatures were quite warm, so the
atmosphere will likely remain capped to surface-based convection
along this front, with the exception being up around Hays. The HRRR
runs today were showing attempts at convection along the front, but
not until after 00z. The 03-06z time frame will be of most interest,
as the nocturnal LLJ will be ramping up significantly in advance of
the shortwave trough moving into Wyoming this afternoon. The speed
convergence around 850mb will increase quite a bit, and this will be
the primary focus for convection after dark. The best area, though,
will be between I-70 and the Nebraska border. Nevertheless, will
have some 40-50 POPs across central and northern Trego and Ellis
County. POPs will taper off quite a bit south of there down to K96.
Fresh convection that develops at the nose of the LLJ with
uninterrupted inflow will be capable of some large hail to half
dollar size and some 60 mph winds.
Thursday is now looking more complicated that previously thought
regarding severe weather across our neck of the woods. Models are
now showing the main surface low pushing well off to the east
earlier, out near Russel or Great Bend by 21z, with a trailing
boundary southwest from there to another weak surface low in the
northern Panhandles in the dry air. We will have to watch for post-
frontal moisture sneaking back west into far southeast/east central
CO, and this may actually be the best shot for severe convection to
develop and mature into southwest KS. This would be very late,
though, most likely late evening around or after midnight. A general
20-30 POPs is forecast given the uncertainty in placement and timing
of most coherent convection.
.LONG TERM...(Thursday night through Wednesday)
Issued at 320 PM CDT Wed Jun 28 2017
After a couple of cooler days Friday and Saturday with highs in the
80s, we will warm back up Sunday and beyond back into the 90s. POPs
will be back in the forecast Sunday Night and Monday Night as weak
northwest flow aloft will be found across western KS. There is still
some question about how far west adequate moisture will be, so most
of the higher POPs during this time frame will be across eastern
half of the forecast area. By mid-week, subtropical ridge will start
to build in across the Four Corners region which would lead to drier
and hotter weather. The latest ECMWF really shows the 500mb ridge
building in across the region by Thursday of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 613 PM CDT Wed Jun 28 2017
Models late today remain in good agreement with a cluster of
thunderstorms crossing northern Kansas overnight. As these storms
cross north central Kansas around the Hays area between 03z and
09z Thursday a surface boundary/outflow will cross southwest
Kansas resulting in a shift in the wind Thursday morning. Models
differ on how far south this boundary will move with the NAM being
the more aggressive. The NAM also suggests a brief period of MVFR
ceiling behind this boundary between 12z and 18z Thursday. At
this time will favor the more further north solutions and as a
result keep VFR conditions at all TAF sites overnight with a deck
of 8000 to 12000 ft AGL ceilings being possible Thursday morning.
Southerly winds at 15 to near 20 knots can be expected overnight
as a low level jet develops. The NAM and GFS indicate 50 knots in
the 900mb to 850mb level by 06z Thursday so a wind shear group
still appears warranted.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 69 96 65 84 / 10 10 20 10
GCK 65 95 63 82 / 10 10 20 10
EHA 63 98 62 82 / 0 10 10 10
LBL 67 100 65 84 / 0 10 10 10
HYS 67 92 63 82 / 50 10 30 20
P28 72 98 69 87 / 0 0 30 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JJohnson
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1147 PM EDT Wed Jun 28 2017
.AVIATION...
The remnants for the convective complex over Wisconsin earlier is
now working across wrn Lower Mi. Although this is weakening, showers
with a few embedded thunderstorms look probable for the first two to
possibly four hours of the TAF period. In the wake of this activity,
mid level subsidence will hinder additional convective development
during the morning through at least mid afternoon. RAP model
soundings remain supportive of carrying low level wind shear through
daybreak. The onset of daytime heating will quickly transition the
low level wind shear to mechanical turbulence during the morning.
Further deepening of the mixed layer Thurs afternoon will support
gusty s-sw winds, over 25 knots at times.
For DTW...The weakening of the upstream convection will remain
supportive of keeping thunder out of the metro TAF during the
overnight, with the better chances still north of Detroit. Low level
moisture advection during the course of the morning will increase
the chances for clouds based below 5000 ft.
//DTW THRESHOLD PROBABILITIES...
* Low for ceiling 5000 ft or less overnight through Thursday
morning. Moderate Thursday afternoon.
* Low in thunderstorms Thursday morning and early afternoon.
Moderate late Thursday afternoon and evening.
&&
.PREV DISCUSSION...
Issued at 904 PM EDT Wed Jun 28 2017
UPDATE...
Mid level moisture advection this evening proved rather efficient in
generating at least light showers across much of the area. Mid level
moisture transport has been focused across central Lower Mi. This
has led to more persistent showers across the Saginaw Valley and
thumb regions. Earlier model solutions strongly suggested that the
better convective potential through the overnight would shift to the
northern Great Lakes as a longer wavelength trough rotating across
the nrn Great Lakes lifts the low level jet into nrn Michigan. The
ongoing quasi stationary MCS now over the WI/IL/IA border region adds
a level of uncertainty to this. Recent satellite/radar trends
suggest a little more stationary forcing has set up across central
Michigan. The resultant MCV from this convective complex may sustain
this region of enhanced moisture convergence across the northern
sections of the forecast area into the overnight. The approach of
this MCV combined with increasing elevated instability through the
overnight will support a chance for thunderstorms. An update will be
issued to further increase convective chances across the northern
portions of the forecast area. The convectively induced troughing to
the west may actually force some enhanced short wave ridging across
Lake Erie, which may be enough to limit convective chances to the low
chance category across the southern portions of the forecast area
(metro Detroit and points south).
The elevated instability overnight will be marginal, so severe
weather is not expected. Given the excessive rainfall across Central
Michigan this past week, current radar trends bear some watching. The
expectation is for the convection to weaken as it pushes toward the
Saginaw Valley, which should prevent excessive rainfall totals.
PREV DISCUSSION...
Issued at 341 PM EDT Wed Jun 28 2017
DISCUSSION...
Surface low pressure advancing towards the northern Great Lakes
region will continue to push a warm front up across northern WI and
into western MI. Convection from this morning has slowly weakened
and continues to do so as it crosses into Michigan. The warm front
did spark development out ahead of the the morning convection as it
moved across eastern WI. This is what we have been watching with
the activity slightly outpacing some of the model data. 12Z
soundings from both DTX and APX showed quite a bit of drier air in
the column with the ridging that has been in place. While this has
helped in holding off precip, moisture advection coming into the
area should help in maintaining some of the precipitation. Forecast
is on par with the trends as the northern half of the CWA will see
better chances for activity through the later afternoon and into the
evening. Rainfall amounts are expected to stay on the lighter side
through early Thursday morning, generally less than half an inch.
Surface based convection has already started to develop back across
the Midwest this afternoon. This activity is expected to weaken as
it pushes east overnight. Activity is then expected to increase in
coverage Thursday morning as the area remains in the warm sector
coupled with the advancement of the warm front across the area.
There is still uncertainly in just how much coverage there will be
as it moves into the warm sector tomorrow morning. With instability
increasing, SPC has nudged both the marginal and slight risks
northward with main concerns for strong winds during the afternoon
and evening periods. Going into Friday, chances are still there for
storms as the cold front pushes through. Friday looks to be the
best chance for storms as opposed to Thursday, but again will be
dependent on how convection from the previous day plays out. The
entire CWA continues to be highlighted in slight risk for Friday.
Warm air advection will continue to bring warmer temperatures into
the area through the end of the week. Highs on Thursday are
expected to be the warmest for the week with highs warming into the
lower 80s.
A wet weather pattern looks to be in store for Southeast Michigan
during the weekend into early next week. The first wave of low
pressure will move in on Saturday bringing the chance for showers
and thunderstorms diminishing by the afternoon hours. A high
pressure system will then build into the Great Lakes region on
Sunday, bringing relatively dry weather, however, an isolated shower
would not be out of the question. Another wave of low pressure will
then move through the region Monday evening into Tuesday allowing
for chances of showers and thunderstorms yet again. High pressure
then looks to move into the area on Wednesday, bringing drier
conditions. Temperatures will remain seasonal, with high
temperatures hovering around the upper 70s to low 80s, and overnight
lows in the 60s.
MARINE...
Low pressure developing over the western Great Lakes will continue
to support increasing southerly wind over marine areas tonight
through Thursday. Moderate speed will be more common over Saginaw
Bay and over western Lake Erie where channeling and alongshore flow
respectively will enhance gusts. Small craft advisories are in
effect overnight through Thursday evening for these areas as well as
for Port Austin to Harbor Beach around the tip of the Thumb. This
wind pattern will bring in warmer and more unstable air into the
region before easing Thursday night into Friday. The warmer air will
fuel increased thunderstorm activity as low pressure over the
northern Great Lakes Thursday drags a diffuse surface trough through
the region Friday into Saturday.
HYDROLOGY...
Low pressure tracking into the northern great lakes tonight will
pull a warm front into lower Michigan. Thunderstorms in progress
over the Midwest and western Great Lakes will tend to focus more
along this front through central lower Michigan overnight through
Thursday morning. Rainfall amounts are generally expected to be in
the range of one quarter and one half inch north of I-69 through
Thursday morning. Locally higher totals around 1 inch will be
possible due to clusters of thunderstorms.
Additional storms may develop throughout Thursday and Thursday night
as warm and increasingly humid air builds into the region but with a
focus more to the south of the I-69 corridor. Average rainfall
amounts will be generally less than one half inch, but localized
higher amounts in excess of an inch will once again be possible
within any more concentrated areas of thunderstorms. This will be
followed by another low pressure system tracking west of the region
that will maintain the threat for thunderstorms Friday and Friday
night.
The potential for flooding will be dependent on the cumulative
rainfall totals during this active period. Should a more focused
region of heavy rainfall emerge, then the potential for a
corresponding rise of area rivers and streams, as well as minor
flooding will be possible. Central Lower Michigan will remain most
susceptible as the area continues to recover from recent flooding.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 10 PM EDT Thursday for LHZ421-422-441.
Lake St Clair...NONE.
Michigan waters of Lake Erie...Small Craft Advisory until 4 PM EDT Thursday for LEZ444.
&&
$$
AVIATION.....SC
UPDATE.......SC
DISCUSSION...SP/MV
MARINE.......BT
HYDROLOGY....BT
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Green Bay WI
1045 PM CDT Wed Jun 28 2017
Updated aviation portion for 06Z TAF issuance
.UPDATE...
Issued at 640 PM CDT Wed Jun 28 2017
Late aftn runs of HRRR showed hints of storm evolution that we are
seeing presently. Two areas of convection formed, west and south
of GRB service area. Southern bow echo will be main show, with
more scattered storms in west-central Wisconsin. Most short-term
models continue this trend with western convection gradually
weakening and southern storms staying south.
&&
.SHORT TERM...Tonight and Thursday
Issued at 240 PM CDT Wed Jun 28 2017
It`s still tough to get a firm grasp on the severe potential late
today and this evening. Rain persists across much of the area,
though it is diminishing from the west. Mid-level dry slot is
pushing into western Wisconsin, but convection continues to fire
at the nose of the dry slot. Will stick with convective scenario
set forth in the previous AFD and mid-day HWO. Storms are likely
to develop over west-central and northwest Wisconsin during the
middle to late this afternoon, and push across the forecast area
this evening. A separate band of storms developing over southeast
Minnesota and northeast Iowa may graze the southern part of the
forecast area earlier. The late-day/evening storms will pose a
risk of damaging winds and large hail. The risk of tornadoes will
also be present, mainly with any storms near the warm front
lifting into the area.
Tapered PoPs down later tonight, though isolated showers could
linger well past midnight. Gusty west winds are expected Thursday.
Stuck with dry forecast for most of the area, but went with a
chance of showers across the north.
.LONG TERM...Thursday Night Through Wednesday
Issued at 240 PM CDT Wed Jun 28 2017
The weather pattern will remain busy at least through the weekend,
though there are indications that quieter conditions will finally
occur next week. Will use a multi-model blend for much of this
forecast.
Thursday night through Saturday...Conditions will start out quiet on
Thursday night as weak high pressure will initially be present. But
will then see clouds increase late when low pressure moves into
Iowa. With lift increasing ahead of the low, showers could push
into central and east-central WI by sunrise. The models are
trending weaker and further south with the system for Friday.
Scattered light showers will remain possible, but heavier rainfall
looks to occur south of the area. Will keep a slight chance of
thunderstorms across the southern 2 rows of counties, though not
confident that thunderstorms will reach this far north. Skies should
partially clear behind the system for late Friday night into
Saturday morning. However, upper troughing will remain overhead,
which should lead to scattered showers and isolated storms popping
up with heating on Saturday. No significant changes to temps.
Rest of the forecast...Sunday is looking like the better day of the
weekend. A shortwave trough will be dropping southeast across the
Lake Superior region and most likely will not have much impact on
our sensible weather. However, it could provide a few showers to
the region on Sunday night as it pushes a cold front south over the
state. As it stands now, early to middle of next week looks
relatively quiet with high pressure in control.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1044 PM CDT Wed Jun 28 2017
Scattered showers, isolated thunderstorm still possible ahead of
cold front, but main activity will remain south of forecast area.
Occasional IFR ceilings overnight with moist atmosphere ahead of
front, but improving conditions after 12Z.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement until 10 AM CDT Thursday for WIZ022-040-
050.
&&
$$
UPDATE.........JKL
SHORT TERM.....Skowronski
LONG TERM......MPC
AVIATION.......JKL
Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
755 PM CDT Wed Jun 28 2017
.NEAR TERM...(Tonight)
Issued at 755 PM CDT Wed Jun 28 2017
As the sun sets, the few or scattered cumulus are dissipating across
north AL and southern TN. High clouds fanning northeast from the
Gulf Coast region will begin to clip our southern north AL counties
this evening. Deep convection which developed at the northern fringe
of deeper moisture is showing signs of diminishing in west central
into central AL. Short term model trends, including the HRRR still
suggest convection trying to enter north AL around daybreak. Any
activity will be isolated, so have maintained a 20 PoP generally
south of the TN river. However, I have delayed the PoP until after
09z. Otherwise, the forecast grids look good and few other changes
are needed at this time.
.SHORT TERM...(Thursday through Friday)
Issued at 301 PM CDT Wed Jun 28 2017
A return of the above noted moisture and instability will bring an
unsettled end to the work week. Scattered shower/thunderstorm chances
should be across the region Thursday morning as deeper moisture
returns. Upped the ante with likely shower/t-storm chances during the
afternoon, as an upper level system moves across the region from the
southwest. As of now, only "general" thunderstorms intensity wise
are expected with the usual gusty winds, locally heavy rainfall and
sudden lightning strikes. Precip water amounts per the NAM/GFS creep
up into the 1.5 to 2 inch range by Thursday afternoon; which
definitely could support gusty winds, frequent lightning and heavy
downpours.
Rain chances should reduce somewhat Thursday night as the system
passes to our northeast. Still keep some chance of rain in the
forecast given an already unstable atmosphere and past convection.
Business picks up more during Friday, as yet another passing upper
level system provides lift to an already unstable environment, with
more numerous showers/thunderstorms - especially Friday afternoon.
.LONG TERM...(Friday night through Tuesday)
Issued at 301 PM CDT Wed Jun 28 2017
The extended forecast will be unsettled and warm. As we head into
the weekend, an upper level ridge spread across the eastern Gulf and
into the Atlantic will stream moisture into the region and a trough
swinging into the Great Lakes will send a series of disturbances
through. On Saturday, shear will be weak (10-20kts), but as CAPE
values get up to 1-2,000 J/kg, there could be a few strong
thunderstorms. However with the amount of cloud cover expected by
Saturday afternoon instability could be limited. Saturday`s highs
will be in the mid 80s with a heat index in the lower 90s and an
overnight low only cooling down towards 70 degrees.
These main synoptic features will weaken by Sunday but seem anchored
heading into the beginning of the work week. Additional disturbances
combined with daytime heating will provide a lingering chance of
showers and thunderstorms. Temps will warm into the upper 80s/around
90 degrees with overnight lows in the lower 70s. With 70 degree
dewpoints still in place, heat index values also increase from
low/mid 90s on Sunday to the mid/upper 90s on Tuesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 541 PM CDT Wed Jun 28 2017
VFR flight weather conditions should last through most of if not all
of tonight. Low and mid level moisture will increase late tonight
into Thursday which will lead to scattered to broken layers between
015-025agl (possible MVFR) and 040-100agl (VFR). Scattered to
numerous showers and a few thunderstorms are expected to develop by
late morning into the afternoon hours. Have included VCSH at both
KMSL and KHSV after 14Z for now, but may need to include
thunderstorms in future updates when coverage and timing are more
certain.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...17
SHORT TERM...RSB
LONG TERM...JMS
AVIATION...17
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service Wichita KS
628 PM CDT Wed Jun 28 2017
.SHORT TERM...(This evening through Saturday night)
Issued at 300 PM CDT Wed Jun 28 2017
Forecast highlights/challenges continue to focus around
thunderstorm chances this evening/tonight through Friday evening,
and again Sunday into next week.
This evening-tonight...Could see an isolated thunderstorm or two
after 5-7 PM generally north of Great Bend to Salina, as a weak
frontal zone/wind shift approaches from the northwest. Upper
support is negligible to non-existent and surface convergence is
weak, so there`s a chance the cap will not be breached for storm
development. However, if a storm or two can manage to form, strong
instability coupled with modest deep layer shear would promote
severe storms capable of large hail and damaging winds. Thinking
thunderstorm chances will gradually increase in coverage across
northern and northwest Kansas as the evening progresses, mainly
along/north of I- 70, as a strengthening low-level jet impinges on
the nearly stalled frontal zone, and subtle shortwave approaches
from the west. This activity may initially pose a large hail
threat, but should gradually transition to a wind threat, with
sporadic damaging wind occurrences possible.
Thursday...Severe storm development is a bit more uncertain than
previously thought Thursday afternoon-evening. Latest short-term
guidance suggests tonight`s thunderstorm complex will track a bit
further north than previously thought, which makes sense given the
orientation and location of the better 700mb thermal gradient and
RAP instability axis. This lends confidence in Thursday`s frontal
placement from northeast KS, southwest into central and southwest
KS. However, like today weak upper forcing and relatively warm
mid- level temperatures may tend to limit thunderstorm coverage
along the front during the late afternoon, with chances possibly
holding off altogether until the evening and overnight when better
upper forcing approaches from the west and the low-level jet
increases. Regardless, strong instability coupled with modest deep
layer shear will support severe weather with any storms that can
develop during the evening, with the threat transitioning to
isolated damaging wind occurrences and locally heavy rain Thursday
night, as activity moves into eastern/southeast KS.
Friday...Threat for storms could linger over far southeast KS for
Friday afternoon-evening, especially if Thursday night`s
thunderstorm complex remains on the smaller side and doesn`t
accelerate the frontal zone south into Oklahoma. If so, severe
storms along with heavy rain are possible. Otherwise, cooler
weather begins arriving by Friday in wake of the frontal passage.
Saturday...Fairly quiet weather expected, as high pressure builds
south in wake of the frontal passage.
.LONG TERM...(Sunday through Wednesday)
Issued at 300 PM CDT Wed Jun 28 2017
Sunday through mid next week...Low confidence/low predictability
forecast for Sunday and beyond. Operational model consensus
suggests unsettled weather returning for at least Sunday and
Monday as an upper wave slowly migrates over Mid-America. Weak
upper flow should prevent widespread severe storms, although a few
strong to marginally severe storms appear possible given
instability, along with locally heavy rain. Model solutions
diverge from Tuesday and beyond, with the GFS keeping an unsettled
weather pattern all week, and the ECMWF building the upper ridge
from the southwest, resulting in better chances for quiet and warm
weather. For now will carry slight chance to chance pops for
thunderstorm through mid-week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 621 PM CDT Wed Jun 28 2017
Showers and storms may accompany a southward moving cold front
after 06-08z across central KS. Some of this activity may
propagate southeast into portions of southeast KS during the
predawn hours. Flight categories may be reduced across central KS
and perhaps southeast Kansas under the heaviest activity. Breezy
south winds will continue through much of the night across much of
south central and southeast KS but wind gust speed will diminish
after sunset.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 73 96 69 86 / 10 10 40 30
Hutchinson 72 96 66 85 / 10 20 40 20
Newton 72 94 67 84 / 10 20 50 30
ElDorado 72 92 68 84 / 10 10 50 40
Winfield-KWLD 74 94 71 86 / 0 10 40 40
Russell 68 94 64 85 / 40 20 30 20
Great Bend 69 95 65 85 / 20 20 30 10
Salina 70 95 67 86 / 40 20 40 10
McPherson 71 95 66 85 / 10 20 40 20
Coffeyville 73 91 72 86 / 0 0 40 50
Chanute 72 90 70 84 / 10 10 50 50
Iola 71 90 69 84 / 10 10 50 50
Parsons-KPPF 73 90 71 85 / 0 0 40 50
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...ADK
LONG TERM...ADK
AVIATION...MWM
Area Forecast Discussion
National Weather Service Lincoln IL
854 PM CDT Wed Jun 28 2017
.UPDATE...
Issued at 854 PM CDT Wed Jun 28 2017
Thunderstorms, several of them severe and tornadic continue from
northern MO to northern IL and southern WI this evening. A fairly
pronounced break has developed between activity in northern MO and
northern IL where analyses suggest instability has diminished,
while activity to the north continues in the vicinity of a surface
warm front and upper shortwave. In northern MO, stronger
instability characterized by CAPE around 2000 J/KG continues to
fuel a slow moving cluster of strong to severe thunderstorms. This
latter cluster should be the primary concern for west central IL
as it shifts eastward. HRRR model suggests thunderstorm activity
will generally be weakening is it shifts eastward into central IL.
Primary threat should be strong wind gusts by the time it reaches
west central IL. Timing of scattered showers/thunderstorms looks
to be reaching Galesburg by 10 p.m., Illinois River
11p.m.-midnight, I-55 2 a.m. according to latest HRRR and have
made adjustments to forecast to slow down onset of precipitation
accordingly.
Otherwise, warm and somewhat humid conditions on track tonight
with lows reaching about 70 degrees following mid-evening
temperatures in the mid 70s to low 80s. Breezy south winds 10 to
15 mph with higher gusts expected through the night.
&&
.SHORT TERM...(This evening through Thursday)
ISSUED AT 300 PM CDT Wed Jun 28 2017
Not too many changes with the forecast through tonight over CWA.
Mid afternoon surface map has 998 mb low pressure over west
central MN with its cold front extending through eastern NE and
western KS. This front to push se over IA through Thu, getting
closer to central IL and increasing chances of convection with
time. Continued increasing chances of showers and thunderstorms
along and north of I-72 during tonight with best chances (likely
pops) along and nw of the IL river. Currently have scattered
showers and thunderstorms over NW IL moving ENE toward Macomb,
Galesburg and Peru. SPC day1 outlook continues slight risk of
severe storms tonight nw of the IL river while enhanced risk just
nw of Knox county. A marginal risk remains as far se as I-55 for
tonight. This convection enhanced by strong sw low level jet
tonight and developing into an MCS will weaken later Thu morning.
Then more scattered convection to develop during Thu afternoon and
get further south into central IL to about I-70. Breezy SSW winds
have brought in higher dewpoints in the low to mid 60s and will
rise into the upper 60s/lower 70s for Thu. Milder lows tonight in
the upper 60s to around 70F. A very warm and humid day Thu with
highs in the upper 80s (mid 80s by Knox and Stark counties).
.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 300 PM CDT Wed Jun 28 2017
SPC day2 outlook with slight risk of severe storms north of I-70
Thu night for next MCS system, while marginal risk expected about
a county se of I-70. Far southeast CWA will likely stay dry
through Thu night with highest pops shifting into east central and
southeast IL on Friday. SPC day3 outlook has marginal risk of
severe storms across CWA for Fri afternoon/evening and believe
highest risk will be se of I-55 in warm sector. Front appears to
push through southeast CWA during Fri evening and toward the Ohio
river overnight Fri night. This could linger small chances of
convection in southeast IL on Sat, mainly southeast of
Charleston/Mattoon. Humid still on Friday with highs in the mid
80s, except lower 80s along and nw of the IL river. Highs in the
lower 80s on Sat over central IL and mid 80s in southeast IL and
starting to get less humid behind the front as dewpoints slip into
the low to mid 60s Sat afternoon.
A brief period of quiet wx expected across CWA Sat night and
Sunday as weak high pressure settles into area and frontal
boundary moves into the TN river valley. Seasonable highs on
Sunday in the mid 80s, with dewpoints in the lower 60s.
The 12Z GFS and ECWMF models differ with handling wx system early
next work week going into the 4th of July period. Weak surface
high pressure will shift east of IL Sunday night and Monday
allowing more humid tropical air to return to area. The frontal
boundary lifting ne over MO valley on Monday to likely develop
more convection. But models differ on how quickly this convection
gets into central/se IL. Northern IL and possibly northern CWA
could see chances of convection as early as Sunday night
especially after midnight, while rest of CWA to see convection
chances return on Monday and continue through Wed as upper level
trof moves into IA/MO on Tue and into the Ohio river valley next
Wed. Seasonable highs in the low to mid 80s Mon-Wed and humid
conditions expected to prevail.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 700 PM CDT Wed Jun 28 2017
Thunderstorms ahead of a cold front in Iowa expected to push
eastward overnight into the central IL area. Weakening of
thunderstorms is expected as it approaches I-55 corridor and
certainty of TSRA/SHRA diminishes with approach to a KDEC-KCMI
line. As eastward movement of developing thunderstorm complex has
yet to become established, timing still remains uncertain but
following model guidance brought VCTS into KPIA, KSPI, and KBMI in
04-06Z timeframe. In addition, a southwesterly low level jet of
around 45 kts will bring low level wind shear from around 04Z-10Z.
Surface winds to remain breezy, SSW 14-18 kts with higher gusts
much of the night, potentially diminishing somewhat Thursday
as the surface frontal zone approaches from the NW.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...37
SHORT TERM...07
LONG TERM...07
AVIATION...37
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
645 PM CDT Wed Jun 28 2017
.SHORT TERM...(This evening through Thursday)
Issued at 320 PM CDT Wed Jun 28 2017
There is reasonable agreement in the models that a developing 700mb
warm will be the catalyst for thunderstorms across Swrn Neb tonight.
The RAP and HRRR are honing in on the Srn Sandhills and Swrn Neb.
The RAP shows about 2000 j/kg of elevated 750mb computed CAPE just
south of Interstate 80 around 08z-11z.
The on-going jet streak across Nrn Colo and daytime heating appear
to be the genesis for front range thunderstorm development this
afternoon which should intersect the front as they move east this
evening.
There is also a disturbance moving across the Tetons which should
spark storms off the Big Horns. This appears to grow weakly upscale
this evening across Wrn SD which could affect Nrn Neb overnight.
Lastly, some level of storm development is expected on the Laramie
Range which could also move east and affect the Sandhills.
Thus, except for Swrn Neb, fairly disorganized thunderstorm
development is expected tonight.
The model consensus is in excellent agreement Thursday showing a
portion of the upper low across Canada translating east and
southeast through the Dakotas. This would support some sort of
scattered thunderstorm coverage Thursday across Ncntl Neb.
The severe weather potential Thursday hinges on the position of the
aforementioned h700mb front. If the front remains north during the
peak heating period, then severe weather could develop. The blend of
guidance plus bias correction holds the front along Interstate 80
Thursday.
The rain chance Thursday reflects the GFS with higher POPs north of
the 700mb front across Ncntl Neb. Confidence in the forecast
Thursday is below average because of the potential after-effects of
thunderstorms tonight across Swrn and Ncntl Neb. The front could get
held up across KS and never reach Swrn Neb.
.LONG TERM...(Thursday night through Wednesday)
Issued at 320 PM CDT Wed Jun 28 2017
Thunderstorm chances, likely across Ncntl Neb, are still in place
Sunday and Sunday night. The model consensus suggests a westerly
midlevel disturbance will move through Wyoming and catalyze a round
of storms originating off the Black Hills Sunday afternoon. This
would carve through Nrn and Cntl Neb Sunday night. The GFS indicates
about 3000 J/KG of MLCAPE and a 12-14C 700mb nose of warm air
advection edging into Swrn Neb.
Instability increases Monday but the shear weakens as h500mb winds
decrease from 40 kt Sunday to 30 kt Monday. POPs Monday are isolated
for this forecast.
No other significant rain chances are expected at this time as
either instability is limited, Friday and Saturday, or 500mb heights
amplify and ridge which should stabilize lapse rates.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 642 PM CDT Wed Jun 28 2017
Isolated thunderstorms will continue to move to the east across
western Nebraska through the evening. Have included VCTS at both
KVTN and KLBF from 1z. Other storms over wyoming are expected to
move across western Nebraska through the early morning hours of
Thursday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Power
AREA FORECAST DISCUSSION
National Weather Service New Orleans LA
401 PM CDT Wed Jun 28 2017
.SHORT TERM...
A residual frontal boundary stalled across the northern Gulf
Coast will be the focus for high rain chances tonight through
tomorrow and again on Friday as the boundary lifts north. The
upper air sounding this morning showed precip water around 2
inches. This number will creep up about 10% overnight and tomorrow
morning with further column saturation (mainly in the upper
levels) and a slight increase in low level dewpoints. This will
push atmospheric moisture to near the average max for this time if
year. That means rain chances will be very high and the potential
for flash flooding is also above normal. So while it may seem
normal for heavy rainfall in the summer, this seems to be an
uptick above that but not to flash flood watch levels. 1 to 3
inches will be possible through tomorrow afternoon with a focus on
points further south in the CWA. The 80% pops for much of the CWA
may be on the conservative side and possible need overnight shift
to go with 100% as the ECMWF and HRRR suggest. The lower coverage
of QPF of the GFS is why didn`t go to 100 yet.
Model soundings show dry air moving in across all levels on Friday.
This reduction in precip water will result in lower coverage with
convection become more summer-like and diurnally driven. This should
also allow temperatures to moderate back up into the upper 80s.
Tstrm placement looks to shift further north as well with highest
pops along and north of I-12.
.LONG TERM...
Model outputs for this weekend show the Bermuda ridge extending
across the GOM and northern Gulf coast with a northern stream trough
racing across the mid and upper Mississippi River Valley. This will
suppress afternoon convection quite a bit, bring down pops to around
30% Saturday and 10-20% on Sunday. Meanwhile, temperatures will
continue to moderate with highs in the upper 80s to lower 90s.
Going into next week, a piece of the Bermuda Ridge will break off in
the central GOM and try to remain there for a few days. This will
keep most of the CWA dry through Wednesday outside of a random storm
or 2. If anyone gets rain during this time, it will be areas in
SW/Coastal Mississippi or adjacent Louisiana Parishes.
MEFFER
&&
.AVIATION...
Numerous showers and thunderstorms have develop across the area.
Although, convection typically dissipates with sunset, this isn`t
likely today. Showers and storms will persist overnight. Lower
ceilings will continue as well. MVFR conditions will prevail
overnight with periods of IFR conditions as storms move over
terminals and reduce visibilities with heavy rainfall.
MEFFER
&&
.MARINE...
Onshore flow has generally returned and will be in place through
the remainder of the forecast period. A slight compression in the
pressure gradient in the NWRN Gulf has spread into coastal waters
west of the Mississippi River. This will bring winds to right at
15 knots this evening and overnight. Therefore, will have exercise
caution headline in those zones. Winds will gradually weaken each
day there after as a surface ridge develops near the central Gulf.
Seas will mimic the winds and subside from 3 to 5 feet to 2 feet
or less from tonight to next week.
MEFFER
&&
.DECISION SUPPORT...
DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Monitoring Hydro
Decision Support Services (DSS) Code Legend Green = No weather
impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or high
visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
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 risk of severe and/or
direct tropical threats; Events of National Significance.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 71 82 72 86 / 40 70 30 70
BTR 72 84 75 88 / 50 80 40 60
ASD 73 82 75 88 / 70 80 40 60
MSY 75 82 76 88 / 70 80 40 50
GPT 74 81 76 85 / 70 80 40 60
PQL 73 82 75 86 / 70 80 40 60
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
954 PM CDT Wed Jun 28 2017
.MESOSCALE DISCUSSION...
952 PM CDT
West-to-east oriented convection across the northern tier of
northern Illinois counties is bringing an enhanced flash flooding
threat that will last for a few more hours. This includes for
Rockford, Belvidere, and the northern Chicago suburbs. There have
been reports of numerous stalled vehicles on flooded roads in
Winnebago County. The severe weather and tornado threat has waned
due to the cold pool influence, with still a threat of isolated
cores of hail, and some threat on the western end (now Stephenson
County) of wind and a small tornado threat.
The deep convection is part of a now elongated MCS across central
Lake Michigan back into far northern Illinois. A 45-50 kt low-
level jet (LLJ) as sampled by VWP continues to replenish this area
with moisture, with this LLJ canceling out cold pool propagation
speed. So while there will still be a southward sag of this area
of storms, the main focus remains over and just south of the FFW
counties. The focus for heavy rain will continue to be across the
four counties presently in a flash flood warning, and even though
there is a present western edge to these storms, redeveloping
storms are possible into the overnight given the moist advection
regime. One thing that may help some is the active area of
convection in northern Missouri that may rob some moisture
replenishment and focus deep into the overnight.
Radar has estimated rainfall of 4+" across Winnebago and parts of
Boone County, with some mesonets having indicated 1.50"-2" in the
past hour. Significant flash flooding, at least for part of the
FFW areas in Winnebago and Boone Counties, will likely continue
into the overnight hours. The message we are stressing is that
this is particularly dangerous for those near creeks and motorists
the remainder of the night, including in and near several urban
areas such as Rockford and Belvidere.
MTF
&&
.SHORT TERM...
221 PM CDT
Through Thursday...
Multiple rounds of showers and thunderstorms, potentially severe,
possible from the remainder of this afternoon through the day
Thursday.
This afternoon, decaying line of showers from early morning MCS
has mostly dissipated with moderate instability building in its
wake across portions of Iowa and northwestern Illinois. A couple
isolated thunderstorms will be possible in the very near term on
the leading edge of the instability gradient as it spreads east
across the CWA, but main concern for more widespread convection
is starting to initiate over north central Iowa early this
afternoon where temperatures have rebounded into the low 80s with
dewpoints around 70. An upper level disturbance is noted moving
slowly east across the Dakotas with a modest surface low
developing in response over west central Minnesota. Convection
should begin to grow upscale late afternoon into the evening as
low/mid level flow strengthens out ahead of these features
allowing convection to congeal and become more linear with time.
Exactly where this occurs remains a bit uncertain with some of the
more recent HRRR runs trending farther west this evening with the
more intense convection. Not quite ready to bite off on this
scenario as the local CWA is expected to quickly destabilize
through the afternoon with partial clearing already developing in
the western counties and moderately strong southerly winds at the
surface transporting high theta-e air into northern Illinois.
Guidance continues to show large cyclonically curved hodographs
this evening which points towards a supercell threat with any
discrete or leading storms, but as the system evolves more
linearly expect the primary severe threat to become damaging
winds. Training and back building also appear possible later this
evening if portions of the line become oriented WSW to ENE with
ENE storm motions expected while Corfidi vectors drop to 5kt or
less out of north or northeast late this evening. Depending on
where this sets up (as mentioned HRRR has shifted this area
primarily west of the CWA), a strong SW LLJ should be able provide
a good feed of unstable high PWat air (in the neighborhood of
1.7-1.8 inches) which will support convection deep into the
overnight hours with an enhanced concern for flooding over this
area.
Upper wave will continue slowly east across Lake Superior and the
Upper Peninsula of Michigan Thursday with deep southwest flow
continuing across much of the midwest out ahead of the wave.
Guidance indicates steepening mid level lapse rate will advect
over the area tomorrow superimposed over dewpoints pushing to
around 70F resulting in much stronger instability as compared to
today. Mid and upper level winds are not forecast to be as high
resulting in more modest deep layer shear, but still sufficient
for a severe threat. Convective debris/cloud cover from overnight
storms always a concern in this type of setup, but given the deep
southwest flow over the region, seems reasonable that much of the
CWA can once again become destabilized allowing thunderstorms to
redevelop during the afternoon, potentially severe assuming we
realize the strong instability.
Deubelbeiss
&&
.LONG TERM...
239 PM CDT
Thursday night through Wednesday...
A period of unsettle weather is setting up for the long term
forecast period. Conditions are settling back to more typically
seasonable weather, with periodic chances for showers and
thunderstorms, high temperatures in the low to middle 80s and
dewpoints in the 60s to low 70s.
The greatest chances for organized showers and thunderstorms will
come early in the period, from Thursday night through Friday as a
quasi-stationary frontal boundary expected to lay out across
southern Iowa, through northern Illinois to southern Lake Michigan
and southern Lower Michigan. This boundary will be the focus for
convective activity ongoing into Thursday evening. The boundary
will slowly push through the CWA, finally pushing east of the CWA as
the associated upper long wave trough pushes ewd across the midwest.
However, while the longwave trough aloft crosses the midwest, weak
instability enhances by cyclonic curvature aloft will keep a chance
for some scattered showers or thunderstorms for the afternoon hours
on Saturday, with the best chances for any shra/tsra likely to be
over ncntrl/nwrn IL and should be largely diurnally driven.
The period most likely to be dry through the longer term forecast
period should be from Saturday night through Sunday as weak
upper ridging and sfc high pressure build across the region.
For Sunday night through much of next week, the period will trend
more towards a low amplitude long wave pattern with relatively light
flow aloft as the stronger westerlies shift well north into Canada.
This will lead to decreasing confidence in sensible weather features
as weather will largely be driven by weak shortwaves tracking
through the relatively weak mid level flow. While the various
longer range model guidance are in relatively decent agreement on
the longer term long wave trends, there are considerable differences
in the timing and strength of individual shortwaves which would
drive the location, timing and intensity of pcpn. So, while the
extended forecast may sound or look like a broken record of chances
for showers and thunderstorms, but it is more likely that there will
be more dry weather than wet weather. With the high level of
uncertainty in the smaller scale details PoPs will be limited to the
slight chance to low chance ranges. Given the low amplitude,
progressive pattern, day to day temperature changes will be minimal
with highs generally in the low to middle 80s and overnight lows in
generally in the 60s.
&&
.AVIATION...
For the 00Z TAFs...
Concerns with the Chicago area TAFs are:
- Strong to potentially severe storms mid-evening with some
showers and scattered storms continuing into overnight.
- Gusty southerly winds this evening with 50 kt southwest winds in
the 1000-2000 ft layer late this evening and overnight bringing
near LLWS criteria.
- Potential for more storms late in the day Thursday into Thursday
evening.
Organizing storms across southwest/south central Wisconsin will
progress southeast into northern Illinois through the evening.
Storms are continuing to show a strong wind threat (40+ kt) that
will enter northern Illinois. Whether or not this extends as far
south as the TAF sites will be close, but more developing
thunderstorms further to the west will at least move over the area
too. So felt it prudent to note higher convective gusts in the TAF
TEMPOs. Confidence in timing is medium-high especially for RFD,
DPA, and ORD. Confidence drops more on specific timing a bit
further south, including MDW and GYY.
While an organized cluster of storms is favored to move in/through
the area during mid-evening, regenerating storms back to the west
or over the area will potentially be a problem through the
overnight. This is a challenge to say how late this will continue.
Do expect that threat to ease southward, but it is certainly
possible storms will be seen a couple hours longer into the
overnight than noted in current TAFs.
There looks to be a gap in upper level disturbances for Thursday
morning and a good part of the afternoon, but potential for storms
does return later Thursday into the evening.
Southerly winds will be gusty through this evening. Convectively
enhanced gusts are likely at least near the airports and that will
disrupt the wind field some for late this evening into early
overnight. Off the deck, a strong low-level jet late this evening
will support near LLWS Cartier.
MTF
&&
.MARINE...
245 PM CDT
Main marine forecast concerns are with a period of gusty south winds
tonight, as an area of unseasonably deep low pressure tracks just
north of the lake.
Deep low pressure tracking across the upper Mississippi Valley and
upper Great Lakes, combined with high pressure parked over the
sern CONUS and eastern Gulf of Mexico Will keep strong sly-swly
winds over Lake Michigan through the night and into Thursday
morning. A weak cold front should cross the lake tomorrow
allowing winds to relax and veer to more westerly. With the
gradient strongest this afternoon and into the evening hours
tonight, winds to 30 kt are likely with an occasional higher gust
to 35 kt or so. High pressure will then build across the northern
plains through the Great Lakes Region through the weekend and into
early next week, bringing an extended period of relatively light
and variable winds. By midweek, the high pressure should finally
build east of the lake, with a series of weak low pressure systems
lifting out of the south high plains and tracking toward the
western Great Lakes. In advance of these systems, flow will trend
to generally southerly. Flow should be relatively weak as the lows
should be weak systems and the pressure gradient over the lake
should be weak as well. These systems should bring periodic
chances for thunderstorms to Lake Michigan, but confidence in
timing is low given the weak flow pattern.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Flash Flood Watch...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ014 until 6 AM Thursday.
IN...None.
LM...Small Craft Advisory...nearshore waters
until 1 PM Thursday.
&&
$$
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Area Forecast Discussion
National Weather Service Melbourne FL
855 PM EDT Wed Jun 28 2017
.UPDATE...
Tonight...A high pressure ridge axis to the north was providing a
light easterly gradient wind, hence boundaries pushed into west
central Florida early. A few patches of rain will end soon, then no
further precip chances are indicated across the interior. Satellite
shows some cloud lines over the Atlantic, so will have to watch for
small coastal rain chances overnight. The HRRR model hasn`t been
showing Atlantic showers and onshore steering flow will be very
weak, so not planning to add any coastal POPs yet.
&&
.AVIATION...
Mainly VFR through sunrise. Local MVFR possible along the coast,
especially after sunrise as the sea breeze starts to set up with
slight chance of showers too. Isolated-scattered sea breeze
showers/storms will affect interior terminals Thu afternoon.
&&
.MARINE...
Tonight-Thu...Good boating conditions. East winds 10 knots or less.
Seas 2 feet or less. Shower or storm chances look low over the
Atlantic waters, with the main coverage Thu afternoon well inland.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
IMPACT WX...Weitlich
AVIATION...Combs
FORECASTS...Lascody