Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/28/19
Area Forecast Discussion
National Weather Service Columbia SC
857 PM EDT Thu Jun 27 2019
High pressure will be centered just to the northeast through
Friday. This dry air mass is forecast to persist and help keep
thunderstorm coverage isolated on Friday. Some increase in
moisture in a southerly flow on the backside of dominate high
pressure farther off the Southeast Coast may promote a more
seasonally typical scattering of afternoon and evening
thunderstorms over the weekend and early next week.
.NEAR TERM /UNTIL 7 AM FRIDAY MORNING/...
Moisture convergence and axis of instability across southern NC
into the Upstate of SC. Showers and storms in this area
affecting the northern tip of Lancaster county for the next hour
or so. HRRR model indicating isolating convection across the
northern Midlands through the evening...then dry overnight.
Time sections show some low level moisture with PWAT values
1.4 to 1.5 inches along with some high level moisture. Not
expecting significant fog with weak low level jet near the
surface and slightly stronger jet around 4k feet. Temperatures
have been consistent over the past couple of mornings with lows
in the middle 60s to lower 70s across the Midlands and CSRA.
With no real change in airmass will continue with persistence
forecast for overnight temperatures.
.SHORT TERM /7 AM FRIDAY MORNING THROUGH SUNDAY/...
General surface high pressure is forecast to remain in the
region with thermal troughing in the forecast area. The models
show this troughing more pronounced Sunday ahead of a cold
front. The front should dissipate before reaching the forecast
area. Upper ridging may be weaker Sunday with upper troughing
mainly affecting the Northeast States brushing the forecast
area. Still, moisture should remain limited with h85 westerly
flow locally. Projected precipitable water values will be a tad
below climatological normals and forecast soundings indicate
high LFC values. The NAM, GFS, and ECMWF MOS have pops less than
20 percent. Believe thunderstorms mainly associated with strong
heating will be isolated. Leaned toward the lower high
temperature guidance based on the recent bias.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The GFS and ECMWF have surface ridging extending from the
Atlantic into the Gulf of Mexico. North of the ridge the models
show troughing in the forecast area. Forecast upper ridging
should keep this moisture shallow. The ridging will also help
bring hot temperatures. The GFS and ECMWF MOS have above normal
temperatures and pops 20 percent or less. Peak heat index values
may be near 105.
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Overnight, there will be periods of high clouds moving from
southwest to northeast on modest upper level flow, but low
clouds should be gone after sunset. Despite light winds all
night, 5K foot winds in excess of 20 knots and a drier than
normal air mass will prevent morning fog at terminals, with the
exception of OGB where there was some rain nearby this
afternoon. Even there, though, it should not cause much in the
way of aviation problems.
With deep layer ridging in place Friday, VFR conditions and
seasonably light winds will prevail.
.EXTENDED AVIATION OUTLOOK...
A more typical summer time pattern will set up across the Midlands
and CSRA through the extended period. As PW values gradually increase
over the weekend into early next week, expect isolated to scattered
mainly afternoon and evening thunderstorms. This will produce
associated restrictions possible Friday through Tuesday. A few
locations may have early morning stratus and fog.
Area Forecast Discussion
National Weather Service Caribou ME
1023 PM EDT Thu Jun 27 2019
A Low pressure over Hudson Bay will cross the area by Sunday and
will be followed by high pressure Monday. Another weather system
will affect the region on Tuesday.
.NEAR TERM /THROUGH FRIDAY/...
10:25 PM Update...Both water vapor imagery and latest model
guidance are showing a well defined shortwave sliding into the
northern part of the area from Quebec. Thunderstorms supported
by cooling aloft and divergence aloft ahead of this shortwave
continue to affect the northern region and will likely persist
well into the evening, weakening around midnight. Forecast was
updated to increase thunderstorm coverage from isolated to
scattered into late this evening over the north. Temps were
lowered a couple degrees where rain has cooled the air a bit.
Also, a dense fog advisory was issued for the coastal zones
where humid air moving of the colder waters will produce some
dense fog overnight.
Tstms will be ongoing into the evening mainly across the w and
nw areas where the best effective shear(30 kts) and CAPE of 1500
joules reside. As the cells move east, they will weaken running
into a more stable airmass. Storms will have the capability of
large hail and very heavy rainfall leading to some ponding of
water. Damaging winds are also a threat into the early evening.
Activity will wind down for a while as the best forcing pushes
east w/the pre-frontal boundary and upper trof. The HRRR was
doing ok with the movement along w/the RAP and NAM12. Expecting
another round of action, not as strong, to move across the
northern 1/2 of the region w/the associated cold front overnight
into early Friday morning. Could see some heavy rainfall w/this
action. Decided to add the mention of heavy rainfall to cover
this. Light winds, surface cooling, and partial clearing should
lead to fog development overnight.
On Friday, fog and low clouds leftover showers to the east in
the morning. Expecting some showers and tstms to develop during
the afternoon across the northern areas as a mid level trof
slides across the region. Instability increases during the
afternoon w/tstms setting up. NAM/GFS soundings indicate v-notch
sounding w/some shear and CAPE potential of 700-1000 joules.
The NAM is most prominent showing decent moisture through 750
mbs. PWATS of 1.2 inches w/K index in the low 30s to allow for
storms to keep going. Cell characteristic will be pulse type
with hail possible. Giving the shear not expected to be that
strong, thinking is wind is not a big threat. Given the higher
PWATS and weak steering flow forecast, heavy rainfall also
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
At the start of the period, a weak ridge of higher pressure
between troughs bring a brief relief from the unsettle weather.
By early Saturday morning another trough will move into northern
Maine bringing a return of the shower activity across the Crown
of Maine. By early afternoon the shower activity will spread
across the CWA, showers and thunderstorms will persist through
the afternoon. By Saturday evening the TSTMs will move east into
New Brunswick. Shower activity will diminish, but will remain
in the area through the end of the period.
The models they were in good agreement overall through the short
term of the forecast period. Loaded a blend of the
GFS/NAM/ECMWF/GEM to smooth out the minor differences in the
.LONG TERM /MONDAY THROUGH THURSDAY/...
Unstable conditions continue through the extended period of the
forecast. An upper level low over northern Quebec will continue
to spin off troughs through the period. A trough will be over
the area at the start of the period. By early Monday morning the
trough will move into the Gulf of Maine, Higher pressure will
ridge through the area on Monday. Partly to Mostly sunny
conditions will become cloudy Monday evening as the next trough
moves into NW Maine by early Tuesday morning. This trough will
move through Tuesday evening, higher pressure will move in and
will remain until overnight Wednesday. Another trough early
Thursday morning through early Friday morning. A weak ridge of
higher pressure will build in at the end of the period Friday
Loaded a blend to smooth out the differences in the models. Used
NAWAVE4 for seas in the coastal waters.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: MVFR this evening dropping down to IFR tonight across
all the terminals w/the potential for LIFR. Conditions are
expected to improve to MVFR Friday morning and then VFR by
afternoon. The exception will be across the northern terminals.
SHORT TERM: Generally Low MVFR to IFR conditions through the
period with unsettle weather conditions. Periods of IFR during
showers and thunderstorms, then conditions will return to Low
MVFR. Brief periods of MVFR to VFR conditions between troughs,
Sunday evening through Monday afternoon and Tuesday evening to
early Wednesday morning.
NEAR TERM: Light sse winds tonight will become sw on Friday w/a
slight increase to 10 kts during the day. Seas will hold at 3-4
ft especially across the outer zones.
SHORT TERM: Winds and seas below Small Craft Advisory levels
through the period.
ME...Dense Fog Advisory until 8 AM EDT Friday for MEZ029-030.
Area Forecast Discussion
National Weather Service Indianapolis IN
1153 PM EDT Thu Jun 27 2019
The AVIATION Section has been updated below.
Issued at 234 PM EDT Thu Jun 27 2019
High pressure in place across the southeastern states will provide
warm and humid summer weather for Central Indiana over the next
several days. Chances for very isolated showers or storms will
continue to persist each afternoon...but most areas will remain
dry...warm and humid through the weekend.
The next best chance for more organized precipitation will be on
Tuesday and Wednesday as upper level weather disturbances will
track into the region as the ridge aloft flattens.
.NEAR TERM /Tonight/...
Issued at 234 PM EDT Thu Jun 27 2019
Surface analysis early this afternoon shows a large area of high
pressure stretching from the middle Atlantic states...across
Kentucky and Tennessee to TX and Louisiana. A warm and humid air
mass was in place across the area with dew points in the mid to
upper 60s. GOES16 shows mostly clear skies across the state...with
a few CU and CI in the area. An MCV was still spinning near the
land between the lakes. Aloft a ridge axis was in place from New
Mexico to Illinois and Indiana. Storms over the upper midwest
were riding the ridge and pushing toward the Great Lakes.
Models suggest little change in the weather pattern tonight or
through the next several days. The surface high and strong
ridging are expected to remain in place. HRRR suggests an isolated
shower or storm will be possible due to diurnal heating...but
coverage may be too low to be worthy of a mention. Time heights
through tonight show only lower level moisture in place along with
subsidence. Thus will trend toward a partly cloudy sky along with
lows close to persistence values.
.SHORT TERM /Friday through Sunday/...
Issued at 234 PM EDT Thu Jun 27 2019
Little change is expected over the next several days in the
weather. The GFS and NAM are consistent in keeping the strong
area of high pressure in place across the southeastern States.
Meanwhile the upper ridge also appears to strengthen. This steers
any upper level support well north of Indiana to Ontario and the
Great Lakes. Thus over the next several days the only forcing
factor will be the diurnal heating of the day to perhaps trigger
afternoon showers and storms. Time heights through Saturday
morning suggest a dry column and broad subsidence as the strong
ridge builds across the area. Furthermore by Saturday and Sunday
forecast soundings suggest 700mb temps rise to or above 10C. Thus
stronger capping develops as the weekend progresses. Therefore
much of the area should remain dry over the next several
days...particularly on Saturday and Sunday. A renegade shower or
storm cannot be ruled out due to the warm and humid air mass in
place...but widespread organized precipitation is not expected.
Thus will trend toward the lowest possible pops provided by the
NBM during each afternoon.
Given the little change in the airmass through the period will
trend temps toward persistence.
.LONG TERM /Sunday night through Thursday/...
Issued at 306 PM EDT Thu Jun 27 2019
As the long term begins, the upper pattern has upper ridging over
central Indiana with very warm temperatures aloft. Generally
accepted the initialization throughout. The upper ridging will
keep mostly hot and humid conditions over the area with little to
no precipitation through Monday. By Monday night, though, the
ridging becomes a bit depressed and flow becomes more progressive,
which will bring with it more chances for off and on showers and
thunderstorms. There are disagreements in the models on the
progression of the upper pattern, but think the initialization`s
handling of this with some low end shower and storm chances along
with temperatures cooling a few degrees (still mid 80s for highs)
by the end of the long term seems reasonable.
.AVIATION /Discussion for the 28/06Z TAF Issuance/...
Issued at 1149 PM EDT Thu Jun 27 2019
VFR conditions are expected for the duration of the TAF period.
However, will not completely rule out some MVFR fog late tonight,
will have to continue to monitor though. Meanwhile, winds will
generally be light and variable.
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1100 PM CDT Thu Jun 27 2019
Issued at 910 PM CDT Thu Jun 27 2019
Instability was very sluggish in returning today in the wake of
the MCS that came through earlier in the day. However, as we got
after 8pm, visible satellite showed a field of accas develop within
the WAA associated with the LLJ. RAP MUCAPE analysis shows this
LLJ is now bringing some instability up from IA, with
thunderstorms developing south of the Twin Cities in response to
all of this. Expect this activity to slowly sag southeast through
the night with the LLJ. Storms will be elevated and should remain
mostly sub-severe, but with MUCAPE in excess of 2000 j/kg and
around 40 kts of effective bulk shear, this activity can not be
completely ignored for a marginal severe hail threat.
.SHORT TERM...(This evening through Friday night)
Issued at 245 PM CDT Thu Jun 27 2019
The primary concern in the short term is the possibility of
convective redevelopment later today and this evening. Latest radar
imagery shows this morning`s activity has finally exited the area,
with just some trailing stratiform precipitation remaining. The MCV
resulting from the morning MCS is working its way northeast toward
western Lake Superior at the current time, and won`t have any
additional impact on our area, except for the subsidence on its
backside which is helping to clear out the cloud cover across the
western and central portion of the area per the latest visible
imagery. HRRR and HopWRF runs still point toward some redevelopment
of convection later today near the instability gradient once it re-
establishes itself. There remains some question on where and when
that will occur, but the current consensus is it would be late
afternoon or early evening near or north of I-94. Any storms that
develop should move east and southeast, with the best chance to see
anything being east of I-35. We`ll need to see how well the
instability recovers across the area, but there is at least some
chance for a few severe storms. The upper ridge will continue to
build into the area Friday and Friday night, with any weak shortwave
energy tracking by to our north. So, once we get rid of any
precipitation tonight it looks like things will be dry Friday and
Friday night with very warm temperatures.
.LONG TERM...(Saturday through Thursday)
Issued at 250 PM CDT Thu Jun 27 2019
Both the EC/GFS have similar model outputs with the mean long
wave pattern through early next week. Thus, the upper ridge that
was forecast to build across the Upper Midwest on Saturday,
remains on track to produce the hottest air mass since last year.
Heat index values, in combination of WBGT depict a higher
potential for heat illness for those who are active outdoors
Saturday. Depending upon when the cold front arrives on Sunday,
southern Minnesota could have another day of these higher values.
I wouldn`t be surprised to see a heat advisory issued for parts of
Minnesota, and west central Wisconsin on Saturday, and possibly
Sunday based on these conditions.
The upper ridge will begin to break down late Sunday, especially
Monday as a short wave moves rapidly eastward across the Canadian
border. Thus, with this short wave, a cold front will arrive. Timing
is questionable but likely it will be another hot day with storms
Past Sunday night, and due to a persistent fast west to east flow
aloft, I can`t rule out any afternoon or evening thunderstorm as
Sunday nights frontal boundary will likely be in the vicinity next
week. As the front holds close to the area, I don`t see any strong
surge of drier air moving southward and this will lead to dew points
remaining quite moist. There also remains uncertainty on
temperatures next week. I am leaning toward holding on above normal
temperatures next week which is more in line with the EC vs. the
GFS. This scenario keeps most of the colder Canadian air mass
farther north compared to the GFS.
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1100 PM CDT Thu Jun 27 2019
Thunderstorms the rest of tonight will remain east and south of
MPX terminals, though some activity will be near EAU for the first
couple of hours. Still lower than normal confidence on cig trends
tonight, but continued to follow the HREF idea with the best
chances of reduced cigs/vis being across central MN. We`re already
seeing stratus and fog expand across northeast MN and expect this
to expand south toward AXN/STC through the night. Low level
moisture will slowly mix out through mid morning Friday, with
mainly sunny skies with light east winds expected by the
KMSP...Still lots of spread in the guidance on cig trends for
tonight. Did add a tempo group in for lower cigs, but still not
convinced we`ll see much develop given where reduced conditions
/OUTLOOK FOR KMSP/
Sat...VFR. Winds SE 5-10G15 kts.
Sun...VFR. Chc TSRA late. Winds SW 5-10 kts.
Mon...VFR. Chc MVFR/TSRA. Winds lgt and vrb.