Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/17/19
Area Forecast Discussion
National Weather Service State College PA
1131 PM EDT Thu May 16 2019
.SYNOPSIS...
A weak front will drop through the area Friday. This front will
remain close to the region keeping the mention of a shower in
the forecast through the weekend into early next week.
Temperatures will continue to moderate through the period.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
New convection is firing over southern Michigan/NRN Indiana and
looks aimed at SWRN PA. The HRRR shows this entering my western
zones between about around sunrise and mainly dissipating as it
passes through my SWRN zones. It does show scattered showers
over much of the remainder of the forecast area, but the overall
coverage suggests being less pessimistic about the rain chances
late tonight and especially during the day Friday.
The increasing clouds and 5-10 mph SW breeze will lead to
overnight min temps generally in the low-mid 50s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
GEFS indicates Highest PWAT air (30-35MM over Western and
Central PA early Friday) will sag south to the Southern Tier
counties of PA by 18Z Friday, with negative LLVL Theta-E
advection across the Central and North. PWAT values by late
Friday afternoon will dip to under 20 MM along the PA/NY border.
Will layer pops for Friday afternoon from only 20-30 percent
across the northern tier of PA where ML capes will be nil,
to near 60 Percent across the Laurels, where CAPE will be on the
order of 1500-2000 J/KG.
Granted, there will likely be a sharper gradient, but there is
still some uncertainty near and just south of the I-80 corridor
whether a few stray showers could wet the ground or we`ll see
dry conditions after the brief bout of dissipating morning
showers/isolated TSRA.
Thunder chances are probably highest late tonight (west) and
then again in the aftn, but mainly in the Scent and SW. SPC does
have much of the southern tier counties in our CWA within their
MRGL risk for svr storms on Friday (DY2).
Temps should rebound to the m60s in the N, but get close to 80F
along the MD border.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
*Trending warmer and more humid Saturday-Monday
*Dry breaks but still can`t rule out a couple of showers or
t-storm through Monday
*Tuesday looks cooler/less humid with increasing chance for rain
into midweek
Rising heights and building upper level ridging will spell a
warmer and more humid sensible wx trend through the weekend
into early next week. While there will be plenty of dry breaks,
we still cannot rule out a few spotty showers or isolated
t-storm during this time. Expect sparse coverage with limited
rainfall.
We are fairly confident that Tuesday will be dry and
and bit cooler/less humid. Model and ensemble guidance shows an
increase in rain risk heading into the middle of next week.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
Clouds will gradually thicken and lower overnight. Ceilings
should drop to MVFR (possibly IFR) over the western highlands
/KJST and KBFD/ by daybreak, with brief vsby reductions
possible in showers.
Included LLWS at all airfields overnight into Friday morning,
as a 30-45 kt WSW low-level jet is expected to push across
central PA.
A weakening area of shra/tsra could brush SW PA towards
daybreak on Friday. A few additional shra/tsra are expected to
develop by afternoon, as a weak cold front crosses the area.
.Outlook...
Fri...AM low cigs and shra possible NW mtns. Scattered aftn
shra/tsra impacts possible.
Sat...Isolated aftn shra/tsra possible western highlands.
Sun...Scattered aftn shra/tsra possible area-wide.
Mon...AM low cigs possible NW mtns. Scattered aftn tsra impacts
possible eastern PA.
Tue...mainly VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Lambert
LONG TERM...Steinbugl
AVIATION...Evanego
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1158 PM EDT Thu May 16 2019
.AVIATION...
A cold front will settle southward across the area overnight. This
will allow drier and more stable conditions to develop under post-
frontal northerly winds. There is the potential for a brief period
of MVFR to low VFR stratus to emerge during the early-mid morning
period immediately behind the front. Any lower ceiling with lift
with daytime heating by midday. The frontal boundary is forecast to
stall across the Ohio valley on Friday, maintaining a dry north-
northeast flow through the day. This will ensure VFR conditions hold
into the evening period.
.DTW THRESHOLD PROBABILITIES...
* Low for ceiling 5000 ft or less through Friday.
&&
.PREV DISCUSSION...
Issued at 848 PM EDT Thu May 16 2019
UPDATE...
Expanding corridor of convection emerging across northern Indiana
late this evening, driven by rapidly diminishing mid level stability
as a plume of higher 850-700 mb moisture works across a weakly
unstable boundary layer. Downstream profile across southeast
Michigan not nearly as favorable, noting the lack of surface based
instability within the existing low to mid 50s dewpoint airmass.
Little evidence to suggest this will change going forward, leaving
simply a narrow window for elevated convection to develop generally
along/south of the I-96 corridor as mid level moisture briefly
increases over the next 3-5 hours. The underlying magnitude of the
deep layer shear could allow for greater organization, but lack of
instability throughout the column will keep this potential to a
minimum. Brief heavy rainfall and small hail the most likely outcome
with any stronger cores early tonight.
PREV DISCUSSION...
Issued at 355 PM EDT Thu May 16 2019
DISCUSSION...
Continue to monitor convective trends for the potential of Severe
Weather across Southeast Michigan this evening. Per RAP based
mesoanalysis, instability recovery has been non-existent to this
point with edge of MUCAPE/SBCAPE back across the IL and IN
stateline. Orphaned off MCV feature with high based glaciated light
shower/virga activity is currently working eastward through portions
of Lower Michigan this afternoon. This activity is on the lead edge
of the 700-600mb warm advection. It is going to take awhile yet to
moisten the low levels and lower LCL heights as dewpoints are still
in the low to middle 50s. Despite convective debris cloud for a good
chunk of today, still expecting air mass change with high end warm
advection event this evening as longer wavelength theta e ridge
propagates through the central Great Lakes region. Long May daytime
and a break out of some sunshine late this afternoon still supports
some lower tropospheric instability recovery. No changes to earlier
thinking. A potential exists for thunderstorm activity this evening
south of a line from Owosso to Mount Clemens. Slight Risk for severe
weather/damaging wind gusts remains conditional to the development
of a forward propagating cold pool. Greatest potential for severe
weather appears set to the approximate 3-6 Z time window generally
south of the I 94 corridor. If the cold pool does not develop, a
marginal risk for large hail will exist for Southeast Michigan.
Limiting factors will be no EML/steep midlevel lapse rates and
relatively high stability in the 2.5-5.0 kft agl layer.
Surface ridge with help from the lake aggregate will expand
southward into Lower Michigan 06-18Z Friday. Composite frontal
boundary/cold front will sag south of the cwa. Forecast soundings
support active subsidence for much of Friday with strong midlevel
inversion in the 4.0 to 10.0 kft agl layer. Proximity of the
composite boundary supports various cloud over southern half of the
cwa. Pleasant temperatures with highs in the middle to upper 60s.
Longwave ridge amplification will for well defined warm front
northward through Southeast Michigan Friday night. Strong forcing
for ascent is progged along the elevated frontal zone centered
between 800-700mb. Current forecasts read likely to categorical PoPs
between 06-12Z Friday. Forecast soundings support high static
stability in the lowest 7.0 kft agl which limits potential for
strong thunderstorm activity.
Amplifying warm sector will bring warmth to Southeast Michigan on
Saturday. Difficult forecast from a gridded perspective with
differential heating boundary wreaking havoc on the guidance. Gut
feeling is that the current forecast is too cold, particularly for
the central and northern cwa. Highs for many areas will likely reach
upper 70s.
A strong surface low over the central Plains will continue to push
into the Great Lakes region early Sunday. Southern lower MI will
already be in the warm sector as the warm front will have pushed
north of the region Sunday morning. By Sunday afternoon, showers and
thunderstorms will move into SE MI from the west as the upper level
trough begins to move over the area. This precip will stay over the
area through Sunday night as the cold front begins to push across SE
MI. The front will be east of the area by Monday afternoon causing a
sizable drop in temperatures for both Monday and Tuesday. A ridge of
high pressure follows the low allowing for drier weather Monday
through Tuesday night. A shortwave develops over the central plains
and begins to move into the Great Lakes region late Tuesday night.
The associated warm front pushes into SE MI Wednesday morning
bringing some rain chances for the daytime Wednesday. The system
moves across Lake Superior into Ontario by Wednesday night with
drier conditions prevailing over lower MI. Ridge of high pressure
moves into the area Thursday.
MARINE...
Episodic thunderstorms during the upcoming week as two cyclones lift
through the Great Lakes region. The first chance will be tonight,
mainly over Lakes Saint Clair and Erie where a low end severe wind
threat will exist. General thunder Fri night will then be followed
by a more organized severe weather threat ahead of a cold front on
Sunday. Wind generally be moderate to fresh and tending to veer from
one day to the next.
HYDROLOGY...
Thunderstorms are forecast to develop and sweep through the southern
half of the area after about 8pm this evening. Although coverage and
intensity of any storms remains uncertain, basin average QPF around
one half to three quarters of an inch will be possible over the
southern two tiers of counties with the probability for higher
rainfall totals increasing with south and westward extent. Showers
and thunderstorms will be common during the next week, returning
again Friday night and Sunday as the parent low lifts through the
area. Another low will follow a similar track during the middle of
next week.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....MR
UPDATE.......MR
DISCUSSION...CB/KDK
MARINE.......JVC
HYDROLOGY....JVC
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Hastings NE
321 PM CDT Thu May 16 2019
.SHORT TERM...(This evening through Friday)
Issued at 309 PM CDT Thu May 16 2019
Short term concerns are centered around thunderstorms this evening
and again tomorrow afternoon and evening. This evening, a stalled
cold front will be the main focus for thunderstorms. Currently, this
front stretches from far southwest Nebraska up through LXN and ODX
and into northeast Nebraska. Given relatively weak forcing aloft, I
expect coverage to remain pretty isolated. In addition, low-level
moisture and deep-layer shear are both a bit lackluster (especially
compared to tomorrow), so I don`t expect any significant severe
weather tonight. That being said, RAP mesoanalysis shows around
1000J/kg of MLCAPE and 20-30kts of effective bulk shear...which
would be marginally supportive of severe storms. Expect
thunderstorms to continue to move to the northeast through the
night, exiting the area by Friday morning.
Stronger forcing arrives on Friday as the main trough. As the front
pushes back north, we will see good instability develop over
Nebraska and Kansas...on the order of 3000-4000J/kg of MLCAPE. Shear
will also increase substantially as the upper trough moves in, with
40-50kts likely over portions of the area. All that being said, the
highest coverage of thunderstorms will likely end up being west and
north of the local area. The surface low isn`t forecast to move into
far SW nebraska until almost 03Z...which isn`t great timing for
severe weather in the local area. Nevertheless, any storms that
manage to develop in this environment could become severe with very
large hail, and damaging hail and possibly an isolated tornado or
two. But again, I want to reiterate that we are expecting the
majority of the severe weather to be north and west of the local
area...primarily over the Nebraska Sandhills.
.LONG TERM...(Friday night through Thursday)
Issued at 309 PM CDT Thu May 16 2019
By Saturday morning, cold front is forecast to have pushed through
the area, so severe weather should focus well to our southeast. Even
so, we will likely have scattered showers and weak thunderstorms
as the upper trough axis moves through.
Sunday should be mostly dry, but will be significantly cooler with
highs only in the upper 50s and 60s across the area. That is almost
30 degrees colder than the high temperatures that we`re seeing
today.
The cool pattern continues Sunday night into Monday as the next
trough moves into the area. This brings widespread chances for
rain and thunderstorms Monday through Tuesday. Its still early,
but WPC`s 4-5 day QPF shows 1-3" of rain across this area during
this timeframe...certainly not good news for farmers that are
still trying to get fields planted.
Beyond Tuesday, the area will remain in broad southwesterly flow
aloft, which will lead to a gradual warming trend into the middle
and latter half of the week. Wednesday and Thursday should remain
mostly dry, but the model consensus still keeps some slight
chances for rain and thunderstorms in the area ahead of yet
another western trough that will be approaching the area.
&&
.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Friday)
Issued at 1225 PM CDT Thu May 16 2019
Isolated thunderstorms are expected in the vicinity of the
terminals this evening. Then late tonight, we will see LLWS
develop as the low-level jet increases.
On Friday, winds will remain southerly and increase as the warm
front lifts north.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Mangels
Area Forecast Discussion
National Weather Service Grand Rapids MI
743 PM EDT Thu May 16 2019
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 326 PM EDT Thu May 16 2019
- Several opportunities for showers and storms through next week.
- Strong/severe storms possible Sunday and to a lesser extent this
evening.
- High temperatures inching closer to normal.
&&
.DISCUSSION...(This evening through next Thursday)
Issued at 326 PM EDT Thu May 16 2019
Satellite and regional radar show a MCS moving southeast across NW
Indiana. What was a more broad convective complex this morning has
morphed into a bow echo this afternoon and it moving away from
Michigan. The cwa has been under the cloud shield for much of the
day and this has limited instability over the SW Michigan. It`s
possible as the clouds thin late this afternoon, instability may
increase. A few storms have developed over far southeast Wisconsin.
Latest HRRR shows some convection firing near GRR around 01z and
other short range models have shown this too; we`ll keep high POPS
in the grids this evening for our southern cwa.
Today`s convection was firing along a cold front dropping south and
this frontal boundary will be a player in our weather through
Friday. The boundary will drop south into northern IN tonight, but
begin to move north tomorrow. Showers and storms are possible along
the northward moving frontal boundary from mid afternoon on. The GFS
shows a weak wave moving east across the lake toward 00z and that
may enhance any storms that develop. There is some instability and
shear so a few strong storms are possible.
We`ll be south of the warm front Saturday and so most of the
showers/storms will be north of the cwa. Sunday may be a different
story. A deepening low will move northeast across Wisconsin and
push a cold front east toward lower Lake Michigan. Should be quite a
bit of lift with the front along with instability and shear. LLJ
increases to 50+ knots too so severe storms looks possible from noon
on.
After the Sunday system moves east, the next low that will affect us
will arrive mid week and give us a chance at showers/storms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 743 PM EDT Thu May 16 2019
Showers and thunderstorms will remain scattered this evening with
the highest chances across far southern Lower Michigan. Some brief
IFR is possible with heavier storms. Areas of IFR are also
possible across southern Lower Michigan after midnight as low
stratus with ceilings blo 1000 feet.
&&
.MARINE...
Issued at 326 PM EDT Thu May 16 2019
Northwest winds 10 to 20 knots will become northeast overnight.
Waves through Friday are expected aob 3 feet.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
SYNOPSIS...04
DISCUSSION...04
AVIATION...Ostuno
MARINE...04
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
940 PM EDT Thu May 16 2019
.SYNOPSIS...
Low pressure over the Great Lakes this evening will move through
the region on Friday bringing another round of showers and cool
temperatures to the area. High pressure will arrive on Saturday
with drier conditions and warmer temperatures. Showers are
again possible on Sunday as a warm front lifts into the region.
Significantly warmer will likely arrive behind this front for
the day Monday before a cold front brings temperatures back to
around normal for this time of year for the middle of next week.
&&
.NEAR TERM /THROUGH FRIDAY/...
930 PM Update...
Satellite imagery shows drier air now moving through eastern New
Hampshire and western/central Maine. Addition cloud cover is
moving in aloft from Canada. In the meantime temperatures will
continue to fall at a good clip with dew points in the upper 30s
and lower 40s across the region. Only a few tweaks to the
forecast a this point with warmer air aloft arriving overnight
ahead of the next system.
630 PM Update...
Weak ridging is building in tonight allowing for a brief
decrease in rain and cloud cover/opacity overnight. Made a few
minor changes to the forecast for current temperature and dew
point trends. Precipitation timing towards morning looks on
target and close to most recent NAM Nest and HRRR runs.
Previous discussion...
High Impact Weather Potential: Minimal.
Pattern: After a bright morning...cool air aloft associated with
departing shortwave trough has resulted in another cool day
withs some light showers across the region. Upstream...a narrow
short wave ridge axis in the mid levels of the atmosphere is
building towards the region from the west. This...and it/s
associated reflection at the surface will move overhead
tonight...but progressive northwesterly flow aloft will usher in
another shortwave which will be west of the region but
beginning to impact the area by daybreak Friday. Thus...forecast
concerns are centered around precipitation chances as this
wave...and associated fast-moving surface low pressure system
approach from the west.
Through this evening: Sprinkles/light showers continue along a
band from Littleton, NH south and east through the Midcoast
/given cyclonic flow and impressive lapse rates in the 0-10kft
layer/...with additional activity arching southwest along the
coast of ME and NH. This will continue through mid evening
before cooling boundary layer temperatures will stabilize things
and bring this activity to an end. Temperatures will fall back
into the 50s south of the mountains by 8pm...with values
reaching the upper 40s by this time for many locations from the
mountains north.
Tonight: Low pressure centered just north of Sault Ste. Marie
this evening will move east to a position just north of Lake
Ontario by daybreak Friday...with a surface warm front draped
south and east of this feature to the south and west of New
England. Narrow ribbon of isentropic ascent will allow for top-
down saturation through the night with increasing clouds and
slowly strengthening southerly gradient. SREF/HREF probabilities
along with recent runs of the HRRR suggest shower activity will
begin to encroach on our western zones in the pre-dawn hours
and will increase PoPs from west to east as we reach 7am.
Guidance moisture profiles and HRRR simulated satellite imagery
suggests that opaque cloud cover will not arrive until well
after midnight which should allow temperatures to fall pretty
rapidly...with lows in the mountains likely falling into the
30s...with lower 40s across the remainder of southwestern ME and
some mid 40s over southern NH.
&&
.SHORT TERM /FRIDAY NIGHT/...
High Impact Weather Potential: Minimal.
Pattern: Slowly sharpening shortwave trough embedded in
northwest flow aloft will cross the region on Friday before
drier air arrives Friday night as shortwave and associated
surface low passes east of the region. Primary forecast concerns
are centered around rainfall timing/amounts on Friday.
Friday: Occluded low pressure system moves east through the day
Friday along the international border to a location just north of
western Maine by Friday evening...with a triple point moving
through central VT and southern NH to near KPSM by Friday
evening. Veered LLJ suggests pretty weak forcing for ascent at
the leading edge of 1-1.25" PWAT moisture plume that will reach
southern NH by early Friday afternoon before being pushed to the
south and east. The rain appears to be pretty much a daytime
event...with showers likely coming to a end even over western
Maine towards evening. Based on the position of the triple
point...there is the potential for some weak instability to
reach into southwestern NH...but model soundings are not
conducive to thunder as dry air aloft arrives rapidly by the
middle of the afternoon. As for temperatures...T8s reach about
6C over SW NH during the afternoon /fully mixed would yield near
70F/ but with cloud cover and precipitation...expect that we
will not quite fully reach these values...with middle 60s likely
over southern NH...with lower highs to the north and east of
this which will see showers/clouds longer and will be north of
the triple point. As for precipitation amounts...most locations
will likely see only 0.1-0.2" given the aforementioned weak
forcing...however some enhancement in the terrain is likely with
0.25-0.4" possible here. Certainly not enough to cause any
hydro issues.
Friday Night: Low pressure pulls off the Maine coast Friday
evening and strengthens as it moves to a position over Nova
Scotia by daybreak Saturday. A pretty impressive surge aloft of
dry/Polar air will arrive behind this departing low with PWATs
rapidly falling below 0.5" /-1 to -2 sigma/ with a modest
gradient and cold air advection allowing for northwesterly winds
to continue through the night. The winds...and lack of robust
dry advection in the llevels will keep lows from dropping all
that far with lows ranging from around 40 in the mountains to
the upper 40s over southern NH and along the coast of SW Maine.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
A battle between spring and summer looks to be in the cards for
much of ME and NH Sunday and Monday as a warm front wavers
around the region. Run to run consistency hasn`t been very good
over the last couple of days and this may result in fairly large
temperature bust potential Sunday and possibly again on Monday.
First thing first, Saturday looks to be a nice day as a weak
sliver of high pressure builds overnight. This should allow for
at least partial sunshine with high temperatures slightly below
normal.
A warm front approaches Saturday night while sharpening up quite
a bit by Sunday morning. Forcing for ascent will increase Sunday
morning allow for on and off showers much of the day. Even a
few thunderstorms will be possible as instability increases
aloft. the big question is where does the SFC warm front end up
on Sunday. Members of the 12z model suite are offering different
positions, but the main theme is that a sharp warm front should
be draped in W-E fashion somewhere in the forecast area or
nearby. Large temperature errors will be possible. Blended the
available temperature data at this time due to the uncertainty.
However, it could get quite warm in the south.
The same applies for Monday with the SFC warm front slowly
moving its way northward. Again, warm frontal positions are
hard to pin down this time of year as they tend to struggle.
However, there is general agreement that the forecast area will
get into the warm/moist sector on Monday. Have therefore raised
high temperatures. May very well see the warmest day of the
season thus far with highs reaching 80 in many areas. However,
it wouldn`t take much of a southwestward push from the cooler
maritime air mass to the northeast to wipe out that potential
for some. With a cold front moving in from the west during the
afternoon, have gone with a chance of showers and thunderstorms.
Various models show warm sector SBCAPE values getting well above
1000 J/KG with SFC dewpoints well into the 60s. So something to
watch there in terms of thunder potential.
Cooler, drier air is expected to return for Tuesday and
Wednesday in the wake of the cold front. Thereafter, another
round of WAA-aided precipitation is possible midweek.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term...
Summary: Low pressure will approach the region from the Great
Lakes tonight...passing overhead on Friday before moving into
the Canadian maritimes Friday night.
Restrictions: VFR through at least daybreak Friday. Arriving
frontal system will bring deterioration on Friday in SHRAs with
IFR restrictions likely for our Maine terminals /and
potentially PSM/ with MVFR likely in NH. Conditions will rapidly
improve to VFR Friday night.
Winds: Northwesterly winds 5-10kts with coastal seabreeze
expected through this evening with winds going calm/light-
variable overnight. Southeasterly winds 5-10kts develop on
Friday...becoming southwest over southern NH during the
afternoon before turning northwest around 10kts Friday night.
LLWS: LLWS is not expected through Friday night.
Long Term...VFR Saturday through Saturday night. Areas of
MVFR/IFR ceilings Sunday through Sunday night in association
with a warm front. SFC winds should be light. Better chances of
developing VFR on Monday as warm front pushes northward.
However, there will be a chance of showers and thunderstorms
during the afternoon as a cold front approaches.
&&
.MARINE...
Short Term...
Southerly flow strengthening ahead of approaching low pressure
system will necessitate SCAs with some potential for these to
linger through Friday night as winds shift northwesterly and
strengthen again to near SCA levels.
Long Term...Small craft conditions will be possible Sunday
through Monday night, especially on the ocean waters in
association with an approaching low pressure system from the
west that should cross the waters Monday evening.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
NEAR TERM...Hanes
SHORT TERM...Arnott
LONG TERM...Ekster
Area Forecast Discussion
National Weather Service Huntsville AL
941 PM CDT Thu May 16 2019
.NEAR TERM...(Rest of tonight)
Issued at 941 PM CDT Thu May 16 2019
Thought a quiet night was ahead (except for late night fog in/near
areas that recently received rainfall from convection a few hours
ago). Then a storm recently formed near Holly Pond under a weak
upper level disturbance; that has now drifted SE of the forecast
area. This newer activity appeared to be in response to still high
instability values over the region (+2000 surface based CAPE). This
was mostly capped around 850mb, but lift higher up was able to
overcome this and allow the more recent convection to develop.
Otherwise after a rather warm day, with temperatures rising into the
mid 80s to around 90 (the Muscle Shoals airport joining the 90 degree
club today - with Huntsville doing that on May 8th).
Output from some of the Convection Allowing Models; HRRR, HiRes ARW
and NMM (especially the latter two) where hinting at more convection
firing this evening over the forecast area. The HRRR was not as
bullish as those two were, while the new NAM and RAP were hinting at
very isolated showers. Given the recent showers and the lower level
water vapor view indicating passing upper levels support, will
continue isolated t-storms through midnight. As alluded to above,
areas especially over much of Cullman county that received some
locally heavy rains could have pre-dawn fog formation. Will put that
in as well, sort of following output from MRMS rainfall data.
.SHORT TERM...(Friday through Saturday)
Issued at 221 PM CDT Thu May 16 2019
On Friday, the GFS seems to be keying in on residual moisture from
today/tonight`s convection over AL and middle TN. This appears
overdone and is yielding another potential for scattered to
widespread thunderstorms on Friday within the mid-upper level ridge
position. The NAM seems much more reasonable, and have kept Friday
dry at this point for our area, with a better chance of thunderstorms
over east central AL into GA along the higher terrain. A deeper
southerly flow Friday into Saturday will also moisten low levels and
diminish the steeper lapse rates we are observing today. Suggested
blends appear a few degrees too low for highs on both days
considering today`s temp performance thus far. So have opted to raise
temps a couple of degrees both afternoons. Lows should be in the
lower 60s tonight, and lower to mid 60s on Saturday morning as
greater boundary layer moisture feeds into the area.
.LONG TERM...(Saturday night through Wednesday)
Issued at 221 PM CDT Thu May 16 2019
A cold front associated with an upper-low over the Central Plains
will push east into the Mid-South region late Saturday night, and
approach the Tennessee Valley heading into the day on Sunday. Models
are still not totally resolving the magnitude of this feature and
how far east it will make it on Sunday. Current thinking is that this
feature will likely "wash out" before reaching Alabama. However,
convection associated with prefrontal outflow boundaries/cold pools
will likely move into the region Sunday by late morning and
overspread the region during the afternoon. While cloud cover will
increase steadily through the morning, enough breaks will exist
(along with the strong SW flow) to enhance surface heating and low-
level moisture, allowing for some appreciable instability to develop.
While shear will be somewhat modest, it should be sufficient enough
(along with the aformentioned mesoscale boundaries) to allow for a
few organized strong to marginally severe thunderstorms -- mainly
during the afternoon. Confidence is a little better in this solution
and for this reason have trended PoPs high-end "chance" across most
of the area to "likely" along the AL/MS border. Due to the lingering
mesoscale boundaries, this activity may linger into the overnight
hours on Sunday night before tapering off by early Monday morning.
Thereafter, an upper-level ridge will build into the area, limiting
keeping convection more isolated in nature early next week. As
southwest flow deepens aloft, a humid air mass will begin to advect
in as dewpoints climb into the upper 60s. This, combined with
increased thickness values, would support a warming trend and
potentially hot and humid weather developing by the mid to late part
of next week. Thus, increased confidence exists for above normal
temperatures in the far extended period with highs in the upper 80s
to lower 90s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 653 PM CDT Thu May 16 2019
Strong daytime heating had resulted in an unstable atmosphere, and
development of a few showers and t-storms. Most of that activity
stayed south and east of the terminals this afternoon. Cooling this
evening will reduce shower chances for the overnight. VFR flying
weather should continue into the late night. However, locations that
received wetting rain this afternoon could experience MVFR fog/mist
towards daybreak Fri. VFR weather should otherwise continue into
early afternoon. More strong heating and resultant instability could
initiate the formation of more afternoon convection. Given low
confidence on the when/where, did not include TS in the latter
portion of the TAF.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...RSB
SHORT TERM...17
LONG TERM...AMP.24
AVIATION...RSB
For more information please visit our website
at weather.gov/huntsville.
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
938 PM EDT Thu May 16 2019
.SYNOPSIS...
Northwest flow aloft and southwest flow at the surface will
bring together moisture and lift over the Ohio Valley this
evening, resulting in an enhanced threat for thunderstorms
tonight.
A frontal boundary will sag slowly south across the Great Lakes
region tonight into Friday, leading to a chance for showers and
thunderstorms. High pressure and drier conditions will build
into the region for Saturday before another front brings a
chance of showers and thunderstorms on Sunday. Temperatures will
continue to moderate into the weekend.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A challenging forecast scenario continues to play out this
evening, as one round of convection has exited the ILN CWA, and
another is about to enter.
Current surface analysis indicates that the ILN CWA remains
within a general regime of SSW boundary layer flow, disrupted in
part by the MCS that moved through the southwestern sections of
the forecast area in the past few hours. The area is also on the
edge of a significant increase in 925mb/850mb theta-e, which is
advecting ENE on the southern periphery of a slightly-elevated
trough over the Great Lakes. Convergence developing in this area
(at the nose of the strengthening 850mb flow) has led to storm
development in the IWX CWA, with storms quickly becoming strong
to severe.
These storms will behave much differently than the storms
earlier in the day. The previous storms developed within a
favorable boundary layer air mass, with overall propagation
along the edge of the surface-based instability to the south,
though individual storm motions were more toward the ESE. While
one bowing segment was able to persist into the less favorable
air mass and move into Ripley County IN (prompting a warning)
eventually these cold-pool driven storms ran out of energy to
tap, leading to their weakening with eastward extent. To
contrast, the storms developing now are not tied at all to
surface-based instability, and are instead being fed by a
significant amount of theta-e advection a few thousand feet off
the surface. Despite a stable layer under an inversion near the
surface, these storms are realizing a decent bit of elevated
instability (SPC Mesoanalysis suggests 500-100 J/kg, though it
may be slightly higher given the intensity of the updrafts).
Further, they are also being aided in organization by favorable
shear in the 0-3km layer.
It is difficult to use a model to try to project these storms,
because the models simply do not have these storms developing
this soon. The RAP seems to be slightly ahead of the HRRR in
terms of development, which is good because it would be
charitable to describe the performance of the HRRR today as
poor. Nonetheless, the expectation is for overall storm motions
to the E / ESE and a gradual propagation more to the SE as the
LLJ continues to feed elevated instability into Ohio. The
northern half of the ILN CWA will be favored (especially along
and north of a line from Darke County OH to Ross County OH) with
more question marks regarding any further southward propagation
into an increasingly stable air mass. The primary threats appear
to be large hail (with deep rotating updrafts) and heavy rain
(potential training) with a much lesser threat for damaging
winds (stable boundary layer).
Previous discussion >
Upper level energy upstream that is firing convection in nw IN
will race over the CWA this late day and early evening,
outpacing the low level forcing in place in western IN and IL.
Near 70 dewpoints running s-n through IL will continue to get
wrung out on the leading edge of this convective complex, but
the upper energy outpacing it and the relative unreceptive
surface features currently over ILN CWA does not favor this
complex to continue to hold together as it pushes into the CWA
on northwest flow aloft.
This is just a mashup of a couple of vastly differing model
solutions this evening, most of which keep convective initiation
at bay and more northwest of the CWA through this evening.
Expect some storms in northern Ohio to lay out a boundary wnw to
ese over the CWA and another round of storms possible early in
the overnight period northwest of metro Dayton. Any storms
overnight will be on the decrease in both coverage and
intensity, dying out towards daybreak.
Storms that are present will have enough shear to maintain a
presence for at least a few hours early tonight, and possibly
but less likely through the overnight period. This shear
increases the threat of these storms to produce large hail if
they are present, which remains in high question at this time.
Overnight lows were raised, particularly in the western third of
the CWA where dewpoints in the mid 60s should be working in and
inhibiting any rapid temperature decreases.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
A relative minimum in thunderstorm activity is expected to start
the day on Friday, but this could ramp up into some storms by
late morning given the boundary that is expected to cross the
CWA and potentially act as a focus for more storms to fire on.
The bulk of the model solutions push the area of rain to the
northeast sections of the CWA while the CAMs fire more robust
activity along the boundary by later afternoon. Played the
middle ground here and had a brief uptick in the potential for
thunderstorms running from nw of Dayton to se of Columbus late
in the day, decreasing sharply with the setting sun tomorrow.
Any activity tomorrow night will lift well northeast of the CWA
overnight.
Highs on Friday were cut slightly everywhere given the expected
cloud cover and potential rain, but by 3-4 degrees in the north
where these conditions are more likely. Overnight lows will
again be mild - 60-65 with the warmer readings southwest of
Cincy and coolest northeast of Columbus.
Forecast probabilities of thunderstorms are unusually low
confidence starting in the immediate near-term and lasting
through Friday given the wholesale differences between models,
until the upper ridge finally begins to build into the region
and southwest flow aloft turns more westerly overnight.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
A mid level ridge will continue to build northward across the
region on Saturday. This will place our area in a somewhat humid
and warm airmass. There could be a low chance of a PoP up
shower or storm during the afternoon, but that`s around 10
percent so have kept the forecast dry. Highs will be in the
lower to mid 80s.
For Saturday night into Sunday, a mid level trough with embedded
short wave energy will pivot northeast from the central/southern
Plains toward the western Great Lakes and middle Mississippi River
Valley. This system now seems to have a stronger surface low and
overall stronger wind field. The mid level ridge will move east on
Sunday while the mid level trough/embedded energy pushes a cold
front east. The timing of the front and associated instability will
play an important part as to whether we see much severe weather
Sunday afternoon and evening. For now, it looks like the slower
progression of the cold front and max diurnal instability favor
points just to our west, and that is where SPC has a slight risk for
scattered severe storms. But given strong wind field and at least
early on low end moderate instability across our west, there will
likely be a marginal risk for isolated severe. A little early to put
in the HWO for now. Otherwise, given the strong wind field and
diurnal mixing, it will be breezy to windy with the windier
conditions slated across the western CWFA. After lows in the 60s,
Highs will range from the upper 70s northwest to the mid 80s east.
As the mid level trough pushes northeast across the remainder of the
Great Lakes Sunday night into Monday, the cold front will push east
as well. Instability wanes fairly quickly overnight, such that only
some scattered showers are expected across the east by morning. Any
lingering pcpn should move out of eastern locations by afternoon
with skies becoming partly cloudy. After lows from the upper 50s
northwest to the mid 60s east, highs will range from the lower 70s
northwest to the lower 80s southeast on Monday.
High pressure at the surface and aloft is expected to move into the
region Monday night, then move east on Tuesday. This should provide
a window of dry weather with near or slightly above normal
temperatures.
The remainder of the extended is still muddled with uncertainty (in
terms of timing) as we head into mid to late week next week. A warm
front will likely move into the region on Wednesday followed by a
cold front Wednesday night into Thursday. Have kept a chance of
showers and thunderstorms in the forecast during this period. Highs
will remain in the 70s to the lower 80s.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
In the next hour or two, some rain (possibly with embedded
thunder) will impact the KCVG/KLUK airports. However, prevailing
conditions should remain VFR. There may also be some brief wind
gusts out of the west at about 25-30 knots.
VFR conditions should prevail for all TAF sites going into the
overnight hours, but there will be another chance of storm
development after 04Z at KDAY and especially KCMH/KLCK. For
now, it remains unclear if the storms will actually impact the
airports, but some MVFR/IFR conditions will be possible if they
do. A period of VCTS has been included at these TAF sites for
the most likely timing. Also, some MVFR ceilings may get into
KCMH/KLCK during the morning hours, but these should dissipate
by early afternoon.
Thunderstorms will again be possible on Friday afternoon for
KILN/KDAY/KCMH/KLCK, mainly from 20Z onward. Otherwise, VFR
conditions are expected, with westerly winds of 10-12 knots and
SCT/BKN cumulus.
OUTLOOK...Thunderstorms may continue into Friday evening.
Thunderstorms will be possible again on Sunday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Franks
NEAR TERM...Franks/Hatzos
SHORT TERM...Franks
LONG TERM...Hatzos
AVIATION...Hatzos
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
727 PM CDT Thu May 16 2019
.UPDATE...
Issued at 726 PM CDT Thu May 16 2019
A blend of the HRRR, RAP, HREF and previous forecast is in place
which produces the best rain chances across swrn Nebraska where
storms are beginning to organize. This storm activity should lift
northeast toward ncntl Nebraska this evening. The HRRR updraft
helicity product suggests a continued chance for strong to
occasionally severe storm development.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 409 PM CDT Thu May 16 2019
The primary forecast challenge over the next couple days is
regarding a surface low centered around the NE/KS/CO point with a
quasi-stationary front wiggling eastward across southern/central Neb
and a dryline extending to the south. This setup favors a double
shot of severe weather for western Neb... one this evening and
another on Friday. Another concern is the temperature forecast as a
large gradient sets up for Friday with highs in the 50s north of the
front to 80s south.
This evening and tonight... Convective initiation is underway across
the western Neb panhandle as of 20z. Spread PoP east through the
evening as further development and intensification is expected along
and north of the stationary front. Coverage through the early
evening hours will remain rather limited with surface dew point
depressions over 30F across SW Neb and at least 20F north.
Supercells are the favored storm type due to iso/sct nature,
somewhat veering wind profile, modest deep layer shear, very steep
lapse rates, and ample instability as indicated by the 20z LBF RAOB.
Large hail appears to be the main threat with decent CAPE in the
hail growth zone and weak shear in the low levels and fairly high
LCL`s (mitigating the tornado threat). Added convergence and forcing
from the LLJ will help transition the convection into multicell
clusters toward dark. Hail will continue to be the concern overnight
with any elevated storms across northern Neb under upslope flow and
better moisture advection.
Friday... The severe threat intensifies across the CWA as the heart
of the negatively-titled upper trough emerges from the Rockies and
the H3 jet noses into the central High Plains. Frontogenesis
increases remarkedly at the surface and in the mid-levels. The low
level moisture draw remains strong, but the advancing dry line and
strengthening cold front increase the convergence. The front`s
placement will be key in determining the area greatest at risk for
severe weather, particularly the tornado threat. Guidance has been
fairly consistent in progging southwest into north central Neb as
the hot zone, mainly from IML to LBF to BBW. Most guidance has the
cap eroded around 21z. CAMS suggest isolated supercells to begin
across SW Neb, merging into a cluster or perhaps MCS/MCV later on
farther northeast. This makes sense given the mean wind being close
to parallel with the boundary and the wind profile eventually
becoming nearly unidirectional. In the meantime, forecast soundings
suggest significant CAPE (over 3000 j/kg) and shear (20 kts of 0-1km
and at least 50 kts of 0-6km) with ample low level helicity, also
noted in a greatly veering wind profile and sickle-shaped
hodographs. Model analogs also hit on active tornado days for
western/central Neb over the past 20 years. Very large hail will
also be possible with these storms given fat CAPE and seasonable
freezing levels. As the supercells merge, deep layer shear remains
strong, increasing the damaging wind potential. The LLJ will be
focused more toward central/eastern Neb, but hail will still be
possible with elevated convection in the cool sector. The flooding
threat also cannot be overlooked. Forecast PWATs are near the 90%ile
of climo, and the wind profile with boundary positions favor
training storms. Another forecast concern is the effect of tonight`s
convection on boundary locations. Synoptically, this pattern is one
of the most favorable for intense weather in recent years.
.LONG TERM...(Saturday through Thursday)
Issued at 409 PM CDT Thu May 16 2019
The upper trough axis bisects the High Plains on Saturday and the
closed low meanders across the northern Plains through Sunday. With
Nebraska being on the cooler side of the surface boundary at this
point, the severe potential decreases, especially heading into
Sunday when highs struggle to leave the 50s and 60s. Left scattered
thunder in for Saturday with highs near 70 and sufficient
instability. Another potent trough and upper low take aim on the
area Monday into Tuesday. This time, the system takes a more
southern route with the low sitting right over the Sandhills.
Temperatures will be more reminiscent of early spring and precip
will be rain showers during the day and possibly rain/snow mix at
night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 625 PM CDT Thu May 16 2019
Scattered showers and thunderstorms continue to develop across
western and southwest Nebraska this evening. Thunderstorms will
continue developing and moving northeastward through the evening
and overnight hours. Expect thunderstorm development to hold off
until late evening across north central Nebraska so did adjust the
timing of vicinity thunderstorms for KVTN later by several hours.
Winds will remain breezy through the evening and overnight hours
out of northeast. Winds will shift to the southeast across
southwest Nebraska tomorrow afternoon ahead of the frontal
boundary. Areas behind the front, mostly across the northern
Sandhills and north central Nebraska will see lower cloud ceilings
tomorrow morning through the afternoon leading to IFR conditions.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...CDC
SHORT TERM...Snively
LONG TERM...Snively
AVIATION...Gomez
Area Forecast Discussion
National Weather Service Louisville KY
1032 PM EDT Thu May 16 2019
.Forecast Update...
Issued at 1032 PM EDT Thu May 16 2019
MCS continues to move to the southeast, heading into southeastern
Kentucky. Recently surface gusts have only been in the 30-40mph
range as the strongest winds remain aloft. Still, brief very heavy
rain and dangerous lightning will continue to be a threat with this
system as it moves through.
Storms have rapidly developed this evening along a surface front
from Nebraska to Ohio. The majority of this convection is expected
to remain to our north, associated with low level jets over the
middle Missouri Valley and reaching from Illinois to Ohio, but
southeast Indiana and the northern Blue Grass could get grazed
during the pre-dawn hours given ESE 850-300mb flow.
Issued at 552 PM EDT Thu May 16 2019
Keeping an eye on an MCS and a supercell to our north diving
southeastward.
The original complex, now moving through the Indianapolis metro, had
been struggling to produce much more than pea sized hail. Recently
though it has begun to bow out and there have been gusts of 60 mph
on the north side of Indianapolis. As this complex continues to head
southeast it will enter an air mass that is more stable with less
moisture in the column and weaker mid-level lapse rates.
Nevertheless, will need to keep an eye on this convection as it may
clip Jefferson County Indiana. Its forward motion has increased in
the last half hour as its gust front pushes forward, so timing is
tricky, but at its current movement it could be in or near the
Madison area between 6:30 and 7:30. By then it will likely be in a
weaker condition that it is now, but will still be capable of gusty
winds and small hail.
A supercell developed earlier near Danville, Illinois, west of the
main complex. That cell is located in a much more unstable
atmosphere with stronger CAPE, much higher PWAT, and steeper mid-
level lapse rates. On its current trajectory it could reach northern
Washington County Indiana around 8pm according to the latest radar
animation. Take that timing and positioning with a large grain of
salt, though, as the storm is still quite a distance away and much
could change, especially if the storm bows and accelerates.
These storms may still pack a punch as they enter southern Indiana,
but should weaken as they approach the Ohio River. As the sun sets
CIN will increase and SPC RAP shows the significant hail parameter
decreasing. We spoke with SPC earlier and they too felt that the
convection should begin to lose some of its intensity this evening
as it moves southward. Still, it will be important to keep an eye on
them as they approach.
&&
.Short Term...(This evening through Friday)
Issued at 300 PM EDT Thu May 16 2019
...Isolated strong storms possible this evening and tonight...
Current radar imagery shows an MCS in IL that is expected to affect
IN/OH and portions of KY shortly after sunset. Aside from some
temporal disagreement, multiple hi-res models have isolated showers
and thunderstorms developing across our CWA, so decided to carry
slight chances during the overnight hours. Gusty winds, hail, and
heavy rainfall will be possible in the stronger or severe storms,
with the best chances for severe weather across northern portions of
the region. Overnight lows will stay warm from SW flow, and are only
expected to fall into the mid 60s.
Friday will be very warm and dry as a ridge begins to build in from
the west. As a result, highs are forecast to climb into the upper
80s and even into the low 90s in urban metro areas. Dewpoints will
be in the upper 60s as well, so Friday looks to be quite muggy!
.Long Term...(Friday night through Thursday)
Issued at 312 AM EDT Thu May 16 2019
Friday through Saturday Night...
By Friday morning, we`ll be on the periphery of the Gulf ridge with
a likely band of showers and storms moving from northern IL through
IN and OH and into WV. Throughout the day, the ridge is expected to
strengthen and this should limit our convective coverage for the
day. Latest guidance suggest it will be a warm and humid day with
highs topping out in the mid-upper 80s. If enough insolation
occurs, we could hit 90 in the Louisville metro area Friday
afternoon. Dry and muggy conditions are expected for Friday night
with lows in the mid-upper 60s.
Ridge axis should continue to build northward slightly on Saturday
resulting in another warm and muggy day with highs solidly in the
mid-upper 80s. Lows Saturday night will remain in the mid-upper 60s.
Sunday through Wednesday...
By Sunday morning, the ridge axis is forecast to break down to our
west while a mid-level wave and associated surface low and frontal
boundary approach from the west. As this feature pushes eastward,
it will pose a threat of severe weather from the Plains and into the
Midwest. However, as it approaches our area, the moisture transport
with the system is sufficiently less. Despite the lesser degree of
moisture, combination of synoptic scale lift and frontal lift should
result in scattered showers and thunderstorms moving through the
region on Sunday. Some storms could be strong with damaging winds
being the main threat.
Frontal boundary may take its time moving through the region as
becomes stretched out and perhaps even occluded. Thus, some chances
of showers and storms seems reasonable across our eastern sections
on Monday, with a decidedly drier pattern evolving from west to east
throughout the day. The upper pattern looks to reamplify a bit on
Tuesday as another strong trough pushes into the Plains. Downstream,
we`ll see ridging over our area which should result in a slightly
drier pattern for Tuesday. Aforementioned Plains trough is forecast
to move eastward and may impact our region around Wednesday. Just
as in the weekend system, the moisture transport with this system
appears to weaken as the boundary heads into the Ohio Valley.
Though, enough lift and upper dynamics suggest at least another
round of showers and storms on Wednesday.
Temperatures through the period will remain quite warm with daily
highs in the in the low-mid 80s with overnight lows ranging from the
upper 50s to the lower 60s.
&&
.Aviation...(00Z TAF Issuance)
Updated at 712 PM EDT Thu May 16 2019
Storms over southern Indiana will continue to cruise to the
southeast but are expected to weaken as they do so. SDF and LEX will
stand the best shot at storms this evening, along with the
possibility of a gust front bringing gusty northwest winds just
ahead of the storms.
Overnight convection will continue to diminish, but some LLWS will
be possible, especially at SDF and LEX, on the edge of a low level
jet from Indiana into Ohio.
Tomorrow should provide uneventful weather, other than some slightly
gusty afternoon winds, with upper ridging building overhead.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...13
Short Term...SSC
Long Term...RJS
Aviation...13
Area Forecast Discussion
National Weather Service Pendleton OR
743 PM PDT Thu May 16 2019
.SHORT TERM...Upper low moving slowly across southern Oregon
this evening with a southeast flow of moisture over the forecast
area. Band of heavier rain that moved through the region earlier
today has pushed north into Washington. Precipitation has
diminished for most locations. Radar indicates a circulation
center vicinity Columbia basin and Yakima valley with enhanced
showers. Models pick up on this and generate additional rain
across the basin into the northeast Oregon mountains overnight.
The main upper low will continue to move east into Idaho on
Friday. Rain over the eastern portion of the forecast area through
afternoon decreasing by evening. Break in the active weather
Friday night and early Saturday with weak ridge overhead. 94
&&
.PREV DISCUSSION... /issued 426 PM PDT Thu May 16 2019/
SHORT TERM...Tonight through Sunday...Latest radar and satellite
imagery show a band of rain showers extending SE-NW from SE Oregon
NWWD to the East slopes of the Washington Cascades. Isolated weak
thunderstorms with some CG Lightning have developed over nrn Oregon
and SRN WA early this afternoon. The radar representation of these
storms has been rather poor thus far with extensive cloud cover
limiting instability despite decent vertical shear. Latest HRRR
suggests that this band of showers will lift northward into
Washington this evening with the TSTM threat exiting all of the
forecast area by 03Z. Showers are expected to redevelop over the
eastern mountains later this evening and overnight. This is where
the heaviest QPF is likely to be with amounts exceeding 1 inch
possible by Friday morning. East slopes of the Washington Cascades
could also see amounts of 1 inch or more by Friday morning. More
rain is likely across the eastern mountains during the day Friday
before tapering off Friday night. It will be mostly dry Saturday in
between storm systems then another storm will move in during the
evening with more rain through Sunday. It will be breezy to windy
across the lower elevations on Friday especially during the
afternoon with west winds of 15-30 mph and some higher gusts.
LONG TERM...Sunday night through next Thursday...Unsettled weather
is expected throughout the long term period and an upper trough will
remain over the western states. The trough will be centered over our
area initially with a closed low over northern California. This will
give us a chance of rain Sunday night with as much as a half inch of
rain in the mountains and up to a quarter inch in the lower
elevations. Monday will see the closed low move into Idaho while a
second low approaches the coast. This will continue a chance of rain
in the mountains and a slight chance in the lower elevations. The
second low will move ashore but will be further south than the first
one. The trough axis will be to our east as well. This will continue
the chance of rain in the mountains and a slight chance in the lower
elevations for Monday night through Tuesday night. Models begin to
differ at this point and some show a drying out while others keep
some showers. With the low in the desert southwest by Wednesday,
have kept chance of showers in the mountains Wednesday tapering off
to a slight chance late Wednesday night and Thursday while the lower
elevations are mainly dry. Temperatures will be mainly in the upper
50s and 60s Monday through Wednesday then perhaps a couple of
degrees warmer on Thursday. Perry
AVIATION...00Z TAFs...Low pressure to our south will send rain
showers through the area tonight through tomorrow morning. Moderate
rain will be possible at times this evening. Have generally kept
ceilings at MVFR levels but occasional MVFR ceilings and
visibilities will be possible with the heavier rain showers. There
is enough instability for a few thunderstorms over the northern
portions of the area late this afternoon so have added a TEMPO for
TSRA from 22Z-02Z to KPSC. Do not have enough confidence to add it
to other TAF sites. Winds will begin increasing this evening from 5
to 15 kts and will reach 15 to 25 kts with gusts to 25 to 35 kts
after 15Z. Perry
HYDROLOGY...Copious amounts of rain are expected tonight from
central and northern Oregon into south central and southeast
Washington. Rainfall amounts of 1-1.5 inches are possible by Friday
morning for the Blue and Wallowa Mountains and the east slopes of
the Washington Cascades. Rain will taper off on Friday but upslope
flow into the eastern Mountains could result in another .5+ inches
before ending Friday evening. More rain is expected Saturday night
through Sunday night with heaviest amounts over the eastern
mountains. The Flood watches currently posted remain in effect and a
Flood Watch has also been issued for the Imnaha River in Wallowa
County. 78
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 48 59 42 70 / 80 70 10 10
ALW 50 60 45 72 / 80 80 20 0
PSC 54 66 47 74 / 70 60 0 0
YKM 51 63 42 70 / 70 50 0 0
HRI 51 64 45 74 / 70 60 0 0
ELN 49 57 40 66 / 80 60 0 0
RDM 42 58 37 65 / 60 30 0 20
LGD 45 53 38 65 / 90 80 20 10
GCD 43 55 35 65 / 80 70 0 10
DLS 51 63 45 73 / 60 30 0 10
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Flood Watch through Saturday morning for ORZ049-050-502-507.
WA...Flood Watch through Saturday morning for WAZ029-030.
Flood Watch until 5 AM PDT Friday for WAZ026-520.
&&
$$
94
Area Forecast Discussion
National Weather Service Raleigh NC
920 PM EDT Thu May 16 2019
.SYNOPSIS...
Bermuda high pressure will hold off the Southeast coast through the
weekend. A strong upper level high will develop across the Southeast
on Friday and continue through the weekend, producing hot and
largely dry conditions.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 920 PM Thursday...
Another very tranquil weather night across central NC as high
pressure was in control. There were some cirrus noted over WVA and
VA spreading south over NC. However, these cirrus were thin and
appear to be limited in coverage. The temperatures were already in
the upper 50s NE NC ranging into the lower 70s south and in some of
the urban centers at mid-evening. Dew points are creeping up into
the 50s (but still not into the uncomfortable range, yet). Expect
some cirrus tonight, but the latest IR and WV satellite data strong
suggests it to be scattered and thin for most of the night. Lows
should settle into the lower 50s NE ranging to near 60 along the
southern tier of counties along US-74.
MCS activity upstream just SW of Cincinnati is moving south and
dissipating this evening, posing no threat to NC. Additional
thunderstorms were developing in the favorable "ridge runner"
position. Models, especially some of the CAMS suggest that one or
more of these areas of convection may congeal into MCS(s) tonight
into Friday and track toward the central Appalachians and Tennessee
Valley. If our dew points can recover into the 60+ range on Friday,
there should be sufficient CAPE with strong heating (highs in the
80s) to support some afternoon or late day remnant storms.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 255 PM Thursday...
Temps will continue to warm above normal with the Bermuda ridge in
place, weak surface troughing through the Piedmont, and rising
heights aloft as mid level ridging builds in from the W. Based on
forecast thermal profiles with warm air aloft and good diurnal
mixing, highs in the upper 80s to lower 90s look reasonable, on the
warm side of statistical guidance and in line with consensus
thicknesses rising into the 1420s.
Precip chances/coverage still appear small but not zero. The
aforementioned MCV is expected to sweep by just to our N or across
extreme N/NE NC early Fri, potentially sweeping a weak boundary
through central NC through early afternoon. PW is projected to rise
above normal, and forecast soundings from the NAM/GFS indicate
sufficient moisture and steepening lapse rates aloft for
electrification, although coverage is likely to be limited as the
ridge builds aloft. Deep layer bulk shear appears marginal at just
20-25 kts, however the latest model runs indicate moderate MLCAPE
through the afternoon. Following the HREF mean depiction, will
mention isolated storms Fri, mainly across the NW and far N early,
translating into S and SE sections in the afternoon. A second weak
wave (likely spawned from upstream convection) is noted by the RAP
crossing VA and NE NC late Fri into Fri night, and this may trigger
additional isolated storms across far N and NE sections after
nightfall as this energy feeds on residual elevated marginal CAPE.
Expect mild lows in the mid-upper 60s under partly cloudy skies. -GIH
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 240 PM Thursday...
Saturday and Sunday: The sub-tropical ridge aloft will gradually
shift eastward from over the Mid-Atlantic and Southeast regions on
Saturday to offshore by Sunday. An upper level shortwave will swing
through the Plains/Midwest and toward the western Great Lakes
through Sunday night. At the surface, the piedmont trough will
weaken over central NC on Saturday. The surface high will build
westward toward the region resulting in southerly return flow aiding
the advection of warm air into the area. Will continue to keep the
forecast dry through Sunday night. Highs in the upper 80s to mid 90s
and lows in the mid to upper 60s Sat/Sat night. Thankfully min RH
values will be in the 40s and heat indices are not expected to be an
issue. Slightly lower highs on Sunday with similar overnight lows
expected.
Monday through Thursday: While there is good agreement between the
models with respect to the overall weather pattern, there is some
uncertainty with respect to how that will translate in terms of
precipitation across central NC.
As the surface low races off to the northeast through New
England/eastern Canada, the trailing cold front will pivot to more
west-east orientation, slowly sliding into the region Mon/Tue. There
could be some resulting showers and thunderstorms Mon/Tue (should
they hold together/re-develop in the lee of the Appalachians), best
chances will be farther west. The parent upper level trough should
move offshore as the sub-tropical ridge once again builds into the
region mid-week. The surface front may briefly stall over the
Carolinas/VA before lifting northward once again as a warm front.
Southwesterly flow at the surface will continue to advect warm,
moist air into the region through the middle of the week, resulting
in fairly persistent temperatures, with highs in the upper 80s to
low 90s and lows in the mid to upper 60s.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 730 PM Thursday...
High confidence of VFR conditions through the TAF period. As a
disturbance moves into the area from the northwest there is a slight
chance of a shower or two at northern terminals by late Friday
morning into the afternoon. Otherwise no restrictions to flight
conditions are expected. Winds will be out of the southwest at 5-10
gusting to 15 kts by afternoon.
Long Term: A chance for sub-VFR conditions with increasing moisture
Sunday morning. The next chance for shower and thunderstorm activity
would be late Monday into Tuesday but confidence is low at this
point.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Badgett
NEAR TERM...Badgett
SHORT TERM...Hartfield
LONG TERM...KC
AVIATION...Ellis