Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/28/18
Area Forecast Discussion
National Weather Service Bismarck ND
959 PM CDT Mon Aug 27 2018
.UPDATE...
Issued at 955 PM CDT Mon Aug 27 2018
Updated pops based on latest radar imagery. Threat of thunder has
ended with the passage of the shortwave trough into southeast ND.
We did add a mention of patchy fog to the far west. think most
areas may see some 3-5SM vsbys in mainly stratus and light shower
activity. However, mesoscale models are pointing at some patchy
fog along the Montana border. Think most will likely be in
Montana, but if we do clear off a bit far northwest to north
central, some patchy fog can not be ruled out. KISN RAP Bufkit
sounding also supports a period of fog.
UPDATE Issued at 633 PM CDT Mon Aug 27 2018
Shortwave tracking along the central ND/SD border is producing
isolated thunder across south central ND. Although stable just
above the surface, enough instability aloft to support some
rumbles of thunder this evening mainly along and south of I-94
from Bismarck to Jamestown. Will keep a mention of thunder through
the evening. Otherwise, made some adjustments to pops based on
latest radar and populated latest sensible weather elements.
Updated text products will be out shortly.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 150 PM CDT Mon Aug 27 2018
Upper low over Central Montana and the associated surface low over
western South Dakota will move east and be the focus for
widespread showers across western and centraL North Dakota
tonight.
Models are in good agreement spreading a quarter to a half inch of
rain across northwest into central North Dakota as the upper low
swings through tonight. Have lowered expectations for
thunderstorms as the CAPE is pretty limited, so went mainly
showers except for the southeast which will be closer to the low
level thermal support. Kept a slight chance for thunderstorms
there tonight.
Temperatures the rest of this afternoon will struggle to reach 60
northwest, to the mid 60s James river valley. Tonight, seeing
lows in the lower 40s west to around 50 southeast. Tuesday will
again be cool, in the 60s as the cool surface high drifts across
the region.
.LONG TERM...(Tuesday night through Monday)
Issued at 150 PM CDT Mon Aug 27 2018
As the remnants of the upper low depart Tuesday night, expect
some residual showers across the north, ending by morning. Dry
weather is forecast Wednesday and Thursday associated with rising
h500 heights. Widely scattered thunderstorms return Thursday
night and Friday with the approach of a Canadian shortwave and
associated cold front. Thursday will be the warmest with high in
the mid 80s across much the region. The Labor Day weekend should
be relatively mid and dry.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 955 PM CDT Mon Aug 27 2018
Kept a VCTS at KBIS and KJMS this evening with a tempo TS at KBIS
with convection just to the southwest and moving northeast.
Otherwise MVFR to occasional IFR ceilings and visibilities in
widespread rain showers through the night. MVFR ceilings remain
through at least 18Z most area with some slow improvement Tuesday
afternoon. Northerly surface flow tonight around 10 knots shifts
more northwest to west on Tuesday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...TWH
Area Forecast Discussion
National Weather Service Caribou ME
1020 PM EDT Mon Aug 27 2018
.SYNOPSIS...
Warm and humid air will remain across northern and eastern
Maine through Wednesday. A strong cold front will cross the area
Wednesday night and will be followed by high pressure at the
end of the week.
&&
.NEAR TERM /THROUGH TUESDAY/...
Update...
High pressure will exit to the east overnight, while a trof
begins to cross the region. Mostly clear/partly cloudy skies are
expected across the region through early morning. Partly/mostly
cloudy skies are then expected overnight with the trof and
clouds from weakening thunderstorm complexes approaching from
the west. The remnants of the weakening thunderstorm complexes
could bring isolated showers to western portions of the forecast
area later tonight. Patchy fog is also possible across the
region overnight. Overnight low temperatures will generally
range from the lower to mid 60s across the forecast area. Have
updated the forecast to adjust for current conditions along with
overnight temperatures and clouds.
Previous Discussion...
Thunderstorms possible for Tuesday afternoon.
The ridge is expected to push eastward tonight as a MCS over
the northern Great Lakes pushes east. This feature is shown by
the RAP and NAM to push into western Maine overnight (after 2
AM) and decay as it hits the ridge. Instability looks marginal
at best overnight, decided to go w/just some showers. Forcing
is weak.
For Tuesday, there does appear to be quite a bit of residual
cloudiness around through mid morning especially across the
central and eastern areas which will squelch organized tstm
activity. Further n and w, atmosphere looks like it will
destabilize w/CAPE potential of 1500-2000 joules. PWATs are
forecast to hit 1.5+ inches w/decent llvl lapse rates of 8.0+
c/km. There is nice 30+ kt jet streak from 850-700mbs to move
across the region w/a sfc trof. 0-6KM shear of 25 kts was noted
on the NAM and GFS soundings.So, tstm potential is there, but
severe development looks to be in question as mid level lapse
rates(850-700) look marginal. There is potential for some tstms
to contain gusty winds given the forecasted shear, but again,
not convinced attm for severe storms. SPC has the region in a
Marginal Risk for severe tstms for Tuesday, but thinking here
is the severe potential is low given what was mentioned above.
Therefore, kept the enhanced wording out of the forecast attm.
Heavy downpours also possible w/any storms given the high PWATs.
Midnight crew can assess this further w/the later guidance.
Cooler temps along the coast w/potential for sea breeze.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Low pressure will pass to the north of the region Tuesday Night.
A cold front will move across the area Wednesday. Low pressure
will move along this front Wednesday. This will result in
showers a possible thunderstorms Wednesday Afternoon. Another
cold front will move across the area Thursday with another round
of showers.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Strong high pressure will build in from the north Friday. This
system is expected to bring dry conditions into Saturday Night.
Clouds will increase again Sunday as a cold front approaches
from the west. Showers are expected early Monday as the front
moves through. Strong high pressure will then build across the
northeast Monday into Tuesday.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: Generally expect VFR conditions overnight.
However, variable conditions will occur with any patchy fog.
Generally expect VFR conditions Tuesday. However, variable
conditions will occur with any showers or thunderstorms, across
mostly northern areas, during the afternoon.
SHORT TERM: FR/MVFR conditions are expected Tuesday Night into
Thursday. VFR conditions are expected Friday into Sunday.
&&
.MARINE...
NEAR TERM: Winds/seas will remain below small craft advisory
levels overnight through Tuesday. Visibilities could be reduced
in patchy fog overnight into Tuesday morning.
SHORT TERM: Have used a 50/50 blend of the Nam and Gfs for
winds. For waves: Southwesterly wind wave will be the primary
wave system into the weekend. Will use NWPS to populate the
waves.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Norcross/Hewitt
Short Term...Mignone
Long Term...Mignone
Aviation...Norcross/Mignone
Marine...Norcross/Mignone
Area Forecast Discussion
National Weather Service Green Bay WI
1043 PM CDT Mon Aug 27 2018
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight
Issued at 259 PM CDT Mon Aug 27 2018
The latest RAP analysis and satellite/radar imagery show a cold
front positioned from northeast Minnesota to eastern South Dakota
and a subtle warm front from around Mosinee to Green Bay early
this afternoon. Storms are just developing south of Duluth at 2
pm. Partial clearing is taking place over southern Minnesota and
southwest Wisconsin ahead of the front, where ML capes are rising
above 2k j/kg. Still quite a bit of inhibition though, but with
further destabilization, strong to severe thunderstorms remain on
track to develop over southern MN later this afternoon. Over
northern WI, outside of a few spotty showers/storms, a relative
lull in the shower/storm activity will continue into early this
evening. As the anticipated thunderstorm complex over Minnesota
moves across northern WI, severe weather potential remains the
main forecast concern.
Tonight...The cold front will slowly sag southeast across
northwest Wisconsin and into central WI by 12z Tue. With help of a
50 to 65 kt low level jet, thunderstorms that develop over
Minnesota are expected to track northeast initially, before
turning east over northern WI this evening. Elevated instability
of 1500-2500 j/kg and deep layer shear of 40-50 kts will support
the possibility of severe weather. Most hourly models show similar
solutions through the evening, and depict a squall line moving
into north-central WI around 02z and northeast WI around 04-05z.
Due to 0-3 km winds of 40-50 kts, damaging straight line winds
will be the main threat, but will also be strong enough for
isolated tornadoes to spin up along the line. They differ,
however, in the evolution of the thunderstorm complex as it exits.
In addition to the severe weather chances, concerned about
training storms as the thunderstorm complex becomes more
orientated east to west after midnight. A few hourly models show
this occurring over central to east-central WI in locations which
received 2-3 inches of rain last night. Because of the
uncertainty, will let the flash flood watch continue through 12z
Tue. The fast moving nature of the system should limit flash
flooding somewhat, with 1-2 inches of rain looking possible at
most locations, but locally higher amounts are also possible where
training occurs.
.LONG TERM...Tuesday Through Monday
Issued at 259 PM CDT Mon Aug 27 2018
Expecting a brief break in the activity Tuesday morning across
most of the area, with a few lingering showers possible here and
there. More thunderstorm development is expected Tuesday
afternoon as a surface cold front will be draped across Wisconsin
and the environment will retain sufficient moisture and
instability along and south of the boundary. Additionally, an
approaching shortwave and enhanced support from the RRQ of the LL
jet will aid in convective development.
Unlike today`s area- wide threat, Tuesday`s severe weather
potential is mainly confined to central/east- central Wisconsin
and southward. This is the area south of the cold front where
MUCAPE values build to around 2000 to 4000 J/kg and bulk shear is
around 50 knots. Large hail and damaging winds are the main
threats. Forecast hodographs are not particularly favorable for
tornado development, but with low LCL heights (possibly around
500 meters) a brief spin-up is not out of the question, especially
considering there may be lingering boundaries from Monday night`s
storms. Localized flooding also remains possible with any storms,
with PWats around 1.5 to 2.25 inches across central and east-
central Wisconsin. Further north, flooding chances appear minimal.
The thunderstorm threat looks to wane by late evening as
instability is lost. A few showers may linger from Tuesday night
into Wednesday morning.
Skies will gradually clear throughout Wednesday, as shortwave
energy departs and weak upper level ridging and surface high
pressure builds in. The dry stretch should last through Thursday,
and then another mid-level shortwave/surface front are progged to
impact the state Friday/Saturday. Timing details have yet to be
fully resolved this far out and stuck with a model blended
solution for the forecast.
Temperatures Tuesday will remain warn and muggy across central and
east- central Wisconsin, with cooler and drier air starting to
filter into the north. Highs will range from around 70 degrees in
Vilas County to the middle 80s in the Fox Valley. High
temperatures will be about 10 to 15 degree cooler on Wednesday
(the coolest day of the week) and then return to near normal by
Friday and through the weekend.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1040 PM CDT Mon Aug 27 2018
The main thunderstorm complex will shift east of the region by
TAF issuance, but a low-level jet and lingering outflow boundary
will combine to produce thunderstorms with heavy rainfall over
parts of central and east central WI for several more hours. This
low-level jet will also produce some LLWS, which should weaken
from west to east overnight into early Tuesday.
Additional strong to severe thunderstorms may develop over the
southeast half of the forecast Tuesday afternoon, along and ahead
of a cold front.
IFR and local LIFR ceilings will develop over north central and
far northeast WI overnight, and linger through much of the day
on Tuesday.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 7 AM CDT Tuesday for WIZ022-035>040-045-
048>050-073-074.
Beach Hazards Statement through Tuesday afternoon for WIZ022-040-
050.
&&
$$
SHORT TERM.....MPC
LONG TERM......KLB
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Lincoln IL
907 PM CDT Mon Aug 27 2018
.UPDATE...
Issued at 907 PM CDT Mon Aug 27 2018
Breezy and warm conditions will prevail across central Illinois
tonight, as the primary focus for convection remains well to the
northwest across the Upper Midwest into the Great Lakes. 02z/9pm
IR satellite imagery continues to show a large cluster of strong
to severe thunderstorms across southwest Minnesota into western
Wisconsin, with general storm movement to the E/NE. While this
activity will not impact central Illinois, earlier runs of the NAM
hinted at the possibility of a few showers northwest of the
Illinois River toward dawn. The HRRR has been consistently dry for
the past several runs, so confidence for precip is waning. Will
maintain just a slight chance PoP late tonight across the far
NW...but think most locations will remain dry through Tuesday
morning.
&&
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 310 PM CDT Mon Aug 27 2018
The heat and humidity will continue in the short term across all
of central and southeast IL through early Tuesday evening. Very
little change in airmass is anticipated with dew points in the mid
70s and temperatures around 90 during the day Tuesday. Resulting
heat index values will be in the 101-106 range for the fourth
consecutive day. Will continue the Heat Advisory headline through
7 pm Tuesday as a result.
There could be just enough forcing ahead of a dampening short wave
forecast to shift across Iowa for some isolated/scattered showers
toward daybreak, mainly west of the upper IL River valley. Many of
the short range models, particularly the 12z convective allowing
models, are holding off on the vast majority of the convective
activity during the day Tuesday. Scattered t-storms could make a
push toward the IL River Valley, but mainly toward early evening.
The heat and humidity will contribute to CAPEs of 2500-4000, but
the best effective shear is expected to be in northern IL.
Nonetheless, will need to keep an eye on lines of storms/bowing
segments approaching the IL River valley during the evening.
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 310 PM CDT Mon Aug 27 2018
The aforementioned thunderstorms are expected to spread into the
rest of central IL early Tue night, eastern IL after midnight and
southeast IL Wed morning. The strength of the storms should
gradually weaken with the loss of instability and especially wind
shear the farther east and southeast they advance. Some re-firing
of convection is anticipated in eastern and southeast IL Wed
afternoon as the synoptic cold front pushes through the area.
Forcing with the front and sufficient instability will be present
in these areas, but shear will be marginal, so any threat of
strong storms looks isolated at this point for Wed afternoon.
Seasonably cool weather is expected on Thursday as high pressure
moves across the Great Lakes to southern Quebec. The medium range
models are trying to push some warm advection showers/t-storms
into western and parts of central IL on Friday, but it will need
to overcome some initial dry air first, so coverage should be
quite scattered.
Rapidly increasing heights/warm air aloft by Saturday will
increase the heat and humidity once again for the holiday weekend
into the mid/upper 80s. However, the medium range models are in
disagreement as to the strength of the upper ridge and associated
short wave troughs trying to move around the periphery of the
ridge. The result would be periods of showers/t-storms Saturday
and Sunday. There is even less certainty about the potential for
convection on Labor Day due to model differences in the location
of the synoptic frontal boundary. Thus, will side with the front
being closer to the I-80 area and have the higher PoPs in the
northern parts of the forecast area from GBG-PIA-DNV.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 639 PM CDT Mon Aug 27 2018
VFR conditions will prevail through the entire 00z TAF period.
Much like last night, a nocturnal low-level jet will develop
across the region tonight...with wind speeds of 40-45kt at about
2000ft aloft. Have included low-level wind shear at all terminals,
beginning at 03z at KPIA...then developing further southeast to
KDEC/KCMI by 06z. S/SW winds will continue through the entire
period, while any significant convection remains well W/NW of the
TAF sites until after 00z Wed.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 7 PM CDT Tuesday for ILZ027>031-036>038-
040>057-061>063-066>068-071>073.
&&
$$
UPDATE...Barnes
SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Barnes
Area Forecast Discussion
National Weather Service Miami FL
812 PM EDT Mon Aug 27 2018
.UPDATE...
Showers and storms over the northwestern portion of South Florida
will continue to diminish through early evening, leaving mostly
dry conditions for the remainder of the night for the western half
of South Florida.
A couple hours ago, the HRRR was picking up on a boundary that was
moving eastward from Southern Palm Beach to northern Miami-Dade
Counties, and was showing shower and thunderstorm activity blow up
along the east coast during the evening hours. However, the boundary
has weakened significantly, and the HRRR has now backed off. I
maintain PoPs around 25-30 percent for the east coast areas
through the night. Based on the latest trends and short term
models, a few showers and perhaps a thunderstorm will be around
the east coast through 05Z, with perhaps a little break from 05Z-
10Z. Then we may see a slight uptick in showers near the east
coast prior to sunrise. So I only made some slight adjustments to
PoPs for the overnight hours to reflect this thinking.
During this update, I also made some slight edits to the PoPs
during the 12-18Z period for tomorrow`s forecast, increasing PoPs
slightly for the northern half of South Florida.
&&
.PREV DISCUSSION... /issued 732 PM EDT Mon Aug 27 2018/
AVIATION...
The easterly winds will continue over all of South Florida Taf
sites tonight into Tuesday. Speeds will be between 5 to 10 knots
tonight before increasing to around 10 knots on Tuesday. There
could be some showers affecting the east coast taf sites tonight
before thunderstorm threat returns to all of South Florida on
Tuesday. Therefore, VCSH for the east coast taf sites tonight,
then VCTS for all taf sites on Tuesday. The ceiling and vis should
remain in VFR conditions, but could fall down into MVFR or even
IFR conditions with the passage of the showers and thunderstorms.
AVIATION...54/BNB
PREV DISCUSSION... /issued 403 PM EDT Mon Aug 27 2018/
DISCUSSION...
This afternoon through Thursday: A weak surface trough moving
westward across South Florida today is helping to enhance coverage
of mid-late afternoon thunderstorms over interior and western areas,
especially over Collier and Hendry Counties. Frequent lightning and
brief gusty winds are the main threats. Expect most of the activity
to push off the west coast and dissipate around sunset or shortly
thereafter.
The large scale weather pattern for our region will continue to be
similar through Thursday with high pressure to the north of the
region. Deep moderate easterly flow will continue to favor a pattern
of scattered nighttime/morning Atlantic and east coast showers
translating into the interior and Gulf Coast during the afternoons
and early evenings. Relatively cool temperatures aloft through
mid-week will continue to support nocturnal convective coverage a
little more than usual for this pattern over the Atlantic and
east coast. Coverage Tuesday and Wednesday should be slightly less
than today over the interior/west because today we had the
surface trough which added some moisture and low-level convergence.
However, CAPE will be above 3000 J/kg both Tuesday and Wednesday,
so the strongest storms may produce some brief gusty winds.
Friday through the weekend: The signal for the end of the week
through the weekend continues to be for a wetter pattern. A
tropical wave, currently along 52W in the tropical Atlantic, is
forecast to cross just south of the state on Saturday. There
continue to be differences between the GFS and ECMWF. The GFS
shows a weaker tropical wave moving through more quickly. The
ECMWF continues to show a stronger tropical wave that moves
through more slowly and hangs around for the entire weekend. Both
models still do not show any further tropical development of the
wave while it is in the vicinity of Florida and Cuba.
Ensemble guidance and long range QPF forecasts don`t currently show
signals for excessive rainfall during this period, but the
combination of deep tropical moisture and stronger easterly flow is
often ripe for locally heavy rainfall across South Florida. Model
blends keep numerous showers and storms in the forecast Friday
through Sunday.
MARINE...
Easterly flow will prevail through the week as high pressure
remains to the north of the region. Speeds will generally be
10-15kts, though Atlantic waters may see ESE winds 15-20kts at
times as a few tropical waves cross the region. Showers and storms
are expected each day, generally affecting the Atlantic waters
during the morning hours and pushing off the Gulf coast during the
afternoons and evenings. Strong wind gusts, locally higher seas,
heavy rain, and lightning can be expected in and near any storms.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 79 90 78 90 / 30 50 30 40
Fort Lauderdale 81 90 81 89 / 30 40 30 40
Miami 79 90 79 91 / 30 30 30 30
Naples 75 91 75 92 / 20 60 20 60
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&
UPDATE...98/ABH
DISCUSSION...98/ABH
MARINE...98/ABH
AVIATION...54/BNB