Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/30/17
Area Forecast Discussion
National Weather Service Bismarck ND
1033 PM CDT Wed Mar 29 2017
.UPDATE...
Issued at 1021 PM CDT Wed Mar 29 2017
Quick update for observed trends through 03 UTC with a quick drop
in temperatures observed across the southwest where cloud cover is
relatively thin. However, do expect increasing cloud cover from
Montana and a near steady temperature trend the remainder of the
night for the southwest.
UPDATE Issued at 819 PM CDT Wed Mar 29 2017
Little change other than to blend to observed trends through 01
UTC as consolidating diurnal rain showers across the Turtle
Mountains will continue to propagate east and fade.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 247 PM CDT Wed Mar 29 2017
Showers and possible thunder highlight the short term forecast.
A shortwave tracking along the international border could spark a
few showers/thunderstorms. Limited CAPE available this afternoon
across northwest and north central ND. Strong shear does exist
over northwest ND and is expected to propagate eastward into
higher CAPE environment. Farther south, warm mid level is limiting
the CAPE. Latest iterations of the HRRR continue to produce
isolated shower activity across central ND this afternoon into the
early evening. Will continue our mention of isolated shower
activity. With only minimal CAPE, will hold off on a mention of
thunder, but a thunderstorm or two can not be ruled out.
Mesoscale models are not indicating significant fog coverage
tonight. With a little stronger gradient and less low level
moisture than the past few nights, will leave out the mention of
fog for now. However, some patchy fog can`t be ruled out.
Upper level ridging ahead of a strong trough should keep most of
us warm and dry on Thursday, although increasing mid and high
level clouds may temper our forecast highs just a bit. The far
west central and northwest could see a shower or two as weak
northern stream shortwave energy encroaches upon a surface trough
over eastern Montana and far western ND.
.LONG TERM...(Thursday night through Wednesday)
Issued at 247 PM CDT Wed Mar 29 2017
A storm system early next week, followed by a warm-up highlight
the extended forecast.
Thursday night through Saturday a weak surface trough and weak
upper level shortwave trough track slowly east across the forecast
area. This will keep minimal precipitation chances in the
forecast, mainly across the west and north. Upper level flow
becomes more zonal on Sunday and a quick moving shortwave trough
tracking along the International border will bring another chance
of showers along the northern tier zones. With each of these
waves, there will be a minimal threat of mixed precipitation
during the late night and early morning hours. QPF amounts are
also minimal with these two systems.
Early next week, a stronger upper trough tracks from the
California coast, across the central rockies and into the cental
plains. Again, the majority of the energy within this split trough
tracks well to our south. However, there does appear to be more
energy associated with the northern stream portion of the trough.
Thus a higher potential for more significant QPF across western
and central ND. There is quite a bit of model spread at this time
with the GFS bringing the system farther north than the EC/GEM.
There is also a wide envelope of solutions within the GEFS
ensemble run. We`ll need to continue to monitor this feature but
for now will utilize a model blend solution which still brings
high chance to likely pops across most of the forecast area early
next week. After this system moves through, there is better model
consensus in building a strong upper ridge over the western and
central U.S. bringing a warm-up to the forecast area by mid to
late in the work week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 1021 PM CDT Wed Mar 29 2017
VFR conditions are forecast across western and central North
Dakota for the 00 UTC TAF cycle.
&&
.HYDROLOGY...
Issued at 247 PM CDT Wed Mar 29 2017
Warm weather over the next few days will continue to encourage
snowmelt and excessive runoff. However, not enough rain is
expected to significantly add to the high water. We will need to
monitor the system early next week as this would bring a better
chance to significantly add to the high water. Although, by this
time we may be nearing the end of the snowmelt.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...twh
LONG TERM...twh
AVIATION...AYD
HYDROLOGY...twh
Area Forecast Discussion
National Weather Service Buffalo NY
1052 PM EDT Wed Mar 29 2017
.SYNOPSIS...
High pressure north of the region will move east tonight while a
low pressure system over the Mississippi Valley draws moisture
northward toward the New York on Thursday. Chances for rain
will increase over far Western New York Thursday afternoon, with
precipitation spreading across all of Western and Central New
York Thursday night. This complex system may bring some thunder
to far Western New York while a brief period of snow will be
possible east of Lake Ontario. The system will change to all
rain by Friday and move east of the region for the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
Overnight...high pressure settles across the region with
increasing high clouds. The will be thin enough to allow for
some radiational cooling, but will hinder the process a bit.
Low temperatures will drop below freezing for most locations,
with the coldest readings in the mid 20s in the North Country.
Friday...model consensus has trended faster with the onset of
precipitation on Thursday. The 18Z and 00Z NAM in particular are
faster, with the HRRR and current radar trends also supporting
the faster trend. Expect rain to enter the Western Southern Tier
around noon, spreading into Buffalo by mid-afternoon and to
Rochester late afternoon. Latest model consensus supports a
start time about 3 hours faster than 12Z based guidance.
This faster timing has other impacts to the forecast, with
cooler high temperatures expected, especially across western
portions. It`s also interesting to note that BUFKIT thermal
profiles support a brief period of rain and snow mix across the
lower Genesee Valley and Finger Lakes regions late Thursday
afternoon. Given the March sun, this is not likely to produce
any accumulation, but it is possible a few snow flakes will be
mixed in at the onset.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
Let there be no doubt...it is going to be wet and unsettled for much
of this period as another soaking rain will be in the offing. The
good news is that the rain will pull away from the region just in
time to give us a fairly nice weekend.
A storm system...currently spawning severe weather across the Lower
Mississippi Valley...will approach our region from the Ohio Valley
Thursday night. A 40kt low level jet ahead of this stacked low will
pump abundant GOMEX moisture up and over a tight H925-70 baroclinic
zone that will be in place over the Lower Great Lakes. A weakly
coupled H25 jet will accompany the isentropic lift...so plenty of
forcing will be in place to interact with a moisture rich (PWAT arnd
1") environment. This will encourage some locally moderate to heavy
rain...and as mentioned in a previous discussion...could support the
potential for elevated convection. Pattern recognition...including
the strength of the warm frontal boundary...has looked impressive
for several days. FINALLY...forecast soundings are suggesting steep
enough lapse rates aloft for elevated CAPE values in excess of 100
j/kg. Will add the chance for thunderstorms to the western zones...
with some enhanced wording for some heavy rain. These should be
focused along an axis of mid-level warm air advection which will
spread from SW-NE Thursday evening. Rain may briefly taper off
behind this across the Western Southern Tier Thursday evening
before the next round of steady rain moves in later in the
night.
For sites east of Lake Ontario...the pcpn could start off as a
wintry mix...so will maintain that wording. Snow should struggle
to accumulate in most areas, but precipitation rates should be
ample for some accumulation across higher terrain. Several
inches are possible across higher terrain before warmer mid-
level air changes precipitation over to rain late in the night.
This is a difficult snow forecast since temperatures will be
very marginal.
The stacked low will drift across the Upper Ohio Valley on Friday...
while its associated warm frontal boundary will push north across
Lake Ontario and the North Country. This will encourage the
steadiest and `heaviest` rain to move across the eastern Lake
Ontario region in the vcnty of the strongest isentropic lift...while
mainly hgt falls and a divergent upper level flow will drive lesser
rains (including some drizzle) over the western counties...and in
particular across the Southern Tier. Will use cat pops across all of
the forecast area. Any mixed pcpn at the start of the day over the
North Country will change to just rain by late morning. Afternoon
temperatures will range form the upper 40s near the Pennsylvania
border to the upper 30s across the eastern Lake Ontario region.
As the upper level support for the complex storm system drifts east
across Pennsylvania Friday night...the initial sfc reflection will
weaken then `jump` (redevelop) off the New Jersey coast. While the
bulk of the moisture will remain in place over the region during the
storms transition to the coast...only limited low level forcing will
persist. This will allow the widespread rain to taper off as a bit
of light rain and/or drizzle...again mainly over the Southern Tier.
Given the light sfc gradient and near saturated conditions...there
will likely be some fog as well...with dense fog possible over the
higher terrain.
While mid level ridging will make its way across the Lower Great
Lakes on Saturday...guidance is suggesting that a weakness in the
sfc pressure field will remain in place over our forecast area. This
will promote enough of a cyclonic flow in the low levels to combine
with leftover low level moisture (trapped beneath a subsidence
inversion) to keep much of the day shrouded under clouds. Temps
Saturday afternoon will be in the mid to upper 40s.
A shortwave in the northern branch will sweep across the St Lawrence
Valley Saturday night...glancing by our forecast area in the
process. While there will still be a fair amount of low level
moisture in place...high pressure nosing south from Hudson Bay
should supply us with fair dry weather. Temps Saturday night will
generally settle into the low to mid 30s.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Ridging moving across the Lower Great lakes should supply us with a
nice ending to the weekend...as at least partial sunshine and H85
temps near zero C will enable afternoon temperatures to get into the
50s (up 40s Ern Lake Ont Region).
Another southern stream closed low over the southern Plains and
Lower Mississippi Valley will amplify a downstream ridge over the
Ohio Valley Sunday night and Monday. This will keep fair dry weather
in place with temperatures remaining a few degrees above early April
norms.
The various medium range guidance packages diverge with their
solutions at this point...as one forecast `camp` opens up the
southern stream closed low and drifts it across our forecast area
late Monday night and Tuesday. The other `camp` keeps the bulk of
the system to our south...with notably lower POPS and QPF. Will
maintain the likely pops over our region on Tuesday to avoid flip
flopping.
While there is low confidence in the guidance for Wednesday...there
is general consensus that our forecast area will be in a lull as far
as pcpn is concerned. Will refrain from the details due to the large
variance among the various ensemble members of the GEFS and ECMWF.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
VFR conditions are expected through Thursday morning with high
pressure across Ontario ridging southward into the region.
High clouds will lower through Thursday morning but still
staying firmly in the VFR category.
Precipitation will spread across the region from west to east
on Thursday afternoon. After a couple hours of precipitation,
this should lower cigs to MVFR.
Outlook...
Thursday night into Saturday...MVFR/IFR with rain. A chance of
thunderstorms Friday night.
Sunday and Monday...VFR.
&&
.MARINE...
Winds will turn easterly by Thursday and southeasterly Friday
as our next storm system passes south of the Great Lakes. Winds
will reach 15-20 knots with the highest waves in Canadian
waters. However, low-end small craft criteria should still be
reached across the Western half of Lake Ontario late Thursday
through Friday. Winds should be out of the northwest following
the passage of the low for the weekend.
&&
.HYDROLOGY...
This system will produce several rounds of rain, with storm
totals generally expected to average in the 1-2 inch range.
Model consensus suggests the highest amounts will be along the
south shores of Lake Ontario. MMEFS ensembles show there is a
good chance that many of the Buffalo and Rochester creeks will
reach action stage, but low probabilities that they will flood.
This said, if QPF exceeds the forecast by even a half inch in
any particular basin, this would likely be enough to reach minor
flood stage since flows are already high going into the event.
Based on this, will add a mention of this possibility to the
HWO.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory from 5 PM Thursday to 5 PM EDT Friday for
LOZ043.
Small Craft Advisory from 2 PM Thursday to 5 PM EDT Friday
for LOZ042.
&&
$$
SYNOPSIS...ZAFF
NEAR TERM...APFFEL/ZAFF
SHORT TERM...APFFEL/RSH
LONG TERM...RSH
AVIATION...APFFEL
MARINE...APFFEL/ZAFF
Area Forecast Discussion
National Weather Service Cleveland OH
926 PM EDT Wed Mar 29 2017
.SYNOPSIS...
High pressure north of Lake Erie will shift to New England on
Thursday. Low pressure will approach from the southern Plains on
Thursday and drift east across Lake Erie on Friday. This system will
move off the east coast Saturday with high pressure expanding across
the local area for the weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Based on latest HRRR and radar pix will adjust pops upward enough to
indicate a small chc for shra for areas around leri for a longer
part of the night as well as a small increase for the nw half in
general. Also inched lows up a degree or two due to current temps
and quickly increasing clouds.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
Deep upper level trough over the Plains will lift into the Mid-
Mississippi Valley on Thursday then across Central Ohio on Friday. At
the surface, a warm front will lift north into the area on Thursday
with the typical delays expected near Lake Erie. Kept
temperatures in the 40s at Toledo with the front not lifting
north of the Lake until Friday. Moisture advection will ramp up
across the area on Thursday and expect a leading band of showers
to lift northeast across the area from mid-morning through late
afternoon. Better chances of rain and increasing chances of
thunderstorms will arrive from the west late in the day with the
approach of a 500mb jet streak. Widespread rain with scattered
thunderstorms expected Thursday night but will have to monitor
to see what role robust convection plays that will develop upstream
across the Mississippi and Tennessee Valley.
Surface low will move into northwest Ohio on Friday morning.
Some breaks will start to develop in the showers as drier air
gets wrapped into the system. Diurnally enhanced showers will
likely fill back in during the afternoon. As the low pulls away
to the east, northerly flow will pull the cold front south
behind it with cooler air returning Friday night and Saturday.
QPF on Thursday and Friday is expected to range from three
quarters of an inch to an inch and a quarter unless moisture
transport gets disrupted by the upstream convection. The
moisture depth becomes shallow by Saturday morning with clouds
scattering out from the north as high pressure builds in.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Overall upper level pattern still progressive with time. Models
suggest periods of ridging with troughiness moving east across the
lower 48. However, deep trough digging into the Pacific northwest
will cause amplification of the ridge in the eastern United States
by mid week.
The forecast area will see transitioning periods of waves of low
pressure alternated with areas of high pressure. So, the current
pattern continues through the early and middle part of next week.
This pattern will still keep the polar jet stream well north of the
area keeping the arctic cold air out of the forecast area for the
time being. Some hints indicate a brief shot of cold air by the end
of the week.
Surface high pressure will exit to the east on Sunday allowing a
southern stream low pressure system to move northeast toward the
area. This system will initially have limited moisture associated
with it but will eventually tap into some gulf moisture by Monday
night and force it north into the area. The low will track east
into the Carolinas by Tuesday allowing high pressure to build in
from the north. The high will push east to the mid atlantic coast as
yet another storm system with limited moisture begins to approach
from the west on Wednesday.
&&
.AVIATION /00Z Thursday THROUGH Monday/...
Ceilings will slowly lower and thicken through the overnight as
a warm front lifts into Ohio on Thursday. MVFR ceilings may
arrive across NW Ohio by mid morning on Thursday with a areas of
light rain beginning shortly after. It will take longer for this
to occur across the eastern half of northern Ohio into NW PA.
Some IFR will be possible with heavier showers in the afternoon.
winds will become east at all locations and increase through the
night. Winds will become gusty at times after 3 am and continue
into the afternoon. Gusts do not appear that they will exceed
the 20 to 25 knot range.
OUTLOOK...Non-VFR continuing into Friday. Non-VFR possible
Sunday night into Monday.
&&
.MARINE...
Winds on the lake will be increasing from the east northeast and it
appears waves will be high enough for the western basin to support
small craft advisory criteria. So, will hoist a small advisory for
the western 2 lake nearshore zones from 2 AM tonight through 5 PM on
Thursday. For the rest of the marine nearshore, winds should be
just offshore to prevent waves from reaching 4 feet. So, will not
issue an advisory for this area. Otherwise, winds are expected to
be fairly light through the rest of the forecast period except
Monday. Winds will increase out of the east-northeast Monday and
will likely need another small craft advisory then.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory from 2 AM to 5 PM EDT Thursday for LEZ142-
143.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC/Adams
SHORT TERM...KEC
LONG TERM...Lombardy
AVIATION...Mullen
MARINE...Lombardy
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1152 PM EDT Wed Mar 29 2017
.AVIATION...
Mid level FGEN banding will bring brief period of -ra/virga early in
the forecast with cigs to lower VFR, but expect widespread cig and
vsby restrictions in rain/br (some snow KMBS?) to hold off until 12z
or so. As low level moisture continues to funnel northeast into the
area, expect cigs to lower to IFR and eventually LIFR at times by
late today as warm front stalls near Michigan/Ohio state line and
low pressure encroaches from the southwest and provides additional
lift (and moisture) for the area.
For DTW...VFR conditions should basically hold through the night
with a transition to MVFR early Thursday morning and most likely IFR
by afternoon/evening. East/northeast flow will persist and gust into
the 20 to 25 knot range during the day Thursday.
//DTW THRESHOLD PROBABILITIES...
* Low for ceilings at or below 5000 feet through 11z, medium 11z-
14z, high beyond 14z Thursday.
* High in precipitation falling as rain, but low that thunderstorm
will impact terminal Thursday.
&&
.PREV DISCUSSION...
Issued at 346 PM EDT Wed Mar 29 2017
DISCUSSION...
Storm system will bring a wet, cold, windy, raw Thursday
across the area. Surface and closed 500mb lows over the Kansas-
Oklahoma border will slowly head northeastward to about eastern lake
Erie by Friday evening. Strong surge of moisture ahead of this
system will bring soaking rain for the area starting tonight through
most of Friday. First shot of precipitation will occur on a
narrow Fgen band modeled to develop tonight anywhere from the M59
corridor as indicated by the RAP to the I69 corridor shown by the
GFS to slightly further north and a tad later by the Nam. Current
satellite and radar trends seem to point more towards the Saginaw
Valley. The forecast problem with any precip from this will be type.
As precip begins to develop lower levels will start off above
freezing which would allow any precip to reach surface as rain. But
with very dry low levels from cool dry northeast flow advecting in,
evaporative cooling and wet bulbing will shift profiles quickly to
right along or slightly below the 0c line mainly north of the M59
corridor. This will lead to a change to snow or rain/snow later
tonight. QPF should be on the light side less then two tenths. Any
snow will be wet with ratios around 8 to 1 leading to any
accumulations less then an inch as surface temps will remain in the
low to mid 30s.
More widespread and heavier overrunning rain will spread across the
entire area Thursday as surface warm front lifts to about the Ohio
border. Warming in the lower levels will slowly push rain/snow line
northward but may not clear northern portions of Midland, Bay and
Huron counties as low level flow will remain more cooler east
northeast. This will leave the possibility of more light
accumulations, mainly on elevated and grassy surfaces. Elsewhere,
surface gradient will tighten as surface low deepens slightly
leading to a brisk and gusty easterly flow keeping highs only in
the upper 30s north to mid 40s far south. Periods of rain will
continue Thursday night through Friday before exiting early Friday
night. There will also be a chance for convection Thursday
afternoon through Friday morning along and south of the elevated
warm front which should stall along the I69 corridor. Instability
will increases as low level warm moist advection combined with
steepening mid level lapse rates with the approaching 500mb low.
Highs Friday will be more mild in the low to mid 50s from the
Detroit area south as the surface low tracks right overhead, to the
40s north.
Saturday looks dry with high temps into the low to mid 50`s for the
afternoon hours. By Sunday afternoon, low pressure over the southern
plain states will have pushed NE into the Ohio Valley. This will
bring in weak chances for rain Sunday afternoon. Chances for rain
are expected to significantly increase for Tuesday; especially over
the southern portions of the CWA. At least some chance of rain will
linger through the week as low tracks over Lake Erie and into the
New England states. Temperatures remain mild through the period.
MARINE...
The central great lakes will remain situated between high pressure
positioned to the northeast and approaching low pressure lifting
from the central plains into the Ohio valley through the end of the
week. The resulting tight gradient will maintain an extended period
of strong winds with an east to northeast component. Easterly
winds strengthen beginning Thursday under weakly unstable
conditions. Strongest winds Thursday night through Friday morning,
where a period of gusts to near gales will be possible over central
and northern sections of lake Huron. Marginal conditions will
preclude issuance of a gale watch at this time. Building wave
heights under this flow will eventually result in small craft level
conditions for the entire lake Huron nearshore waters and outer
Saginaw Bay late Thursday and Thursday night. These conditions will
likely persist through Friday over most locations given continued
northeast flow. Winds and subsequent waves heights will ease as the
the low exits eastward Friday night.
HYDROLOGY...
Multiple rounds of precipitation will lift across southeast Michigan
Thursday through Friday as low pressure slowly advances toward the
region. Precipitation will arrive on Thursday along a lead warm
front. The onset of precipitation Thursday morning will fall as
mainly rain, but a period of accumulating snow will be possible
across the northern Saginaw and thumb region. Additional rainfall
will then occur on Friday as the main low pressure system lifts
across the eastern Great Lakes. Rainfall amounts from three
quarters of an inch to one inch remain forecast over the two-day
period. These amounts spread over two days should result in just
minor rises to area rivers and streams.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory from 5 PM Thursday to 10 AM EDT Friday for
LHZ443.
Small Craft Advisory from 5 PM Thursday to 4 AM EDT Saturday for
LHZ421-441-442.
Lake St Clair...NONE.
Michigan waters of Lake Erie...Small Craft Advisory from 8 AM to 10 PM EDT Thursday for LEZ444.
&&
$$
AVIATION.....DG
DISCUSSION...DRC/DE
MARINE.......MR
HYDROLOGY....MR
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Quad Cities IA IL
632 PM CDT Wed Mar 29 2017
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 330 PM CDT Wed Mar 29 2017
18Z surface data has high pressure over the Great Lakes with a storm
system in eastern Kansas. Dew points were in the 30s and 40s from
the Great Lakes into the central and northern Plains. Dew points in
the 50s and higher ran from the Ohio Valley to the Gulf Coast.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 330 PM CDT Wed Mar 29 2017
The second round of rain is well established across the area and
moving toward the northeast. As moisture and forcing increase
further late this afternoon additional rain will begin to develop
across Missouri into southern Iowa. Trends with the RAP suggests a
layer of unstable air aloft making it into the far southern areas
prior to sunset. This unstable air may allow some embedded
thunderstorms to develop south of an Ottumwa to Galesburg line.
Tonight the areal coverage of the rain will grow and encompass the
entire area by midnight. An unstable layer of air aloft will move
north during the night which is expected to allow embedded
thunderstorms to develop as far north as the highway 30 corridor by
sunrise. No severe storms are expected but small hail cannot be
ruled out from the stronger storms.
Thursday, rain will continue during the morning hours with embedded
thunderstorms possible from the highway 30 corridor on south. During
the afternoon, areal coverage of the rain will slowly decrease from
west to east but embedded thunderstorms will still be possible south
of highway 30.
If a dry layer can develop in the atmosphere Thursday afternoon,
then a few storms south of a Monmouth, IL to Memphis, MO line would
have the potential of producing hail.
.LONG TERM...(Thursday Night through next Wednesday)
ISSUED AT 330 PM CDT Wed Mar 29 2017
Thursday night and Friday...Instability and forcing progs of the 12z
models suggest enough wrap-around support for bands of showers and
some thunderstorms acrs generally the southeastern third of the DVN
CWA earlier on Thu evening, while the rest of the area may just have
patchy sprinkles or drizzle. But then some signs of this activity
coalescing more into a type of DEF Zone of rain with just isolated
embedded thunder along and east of the MS RVR overnight before
shifting east by the pre-dawn hours of Fri morning. Top-down drying
on the fcst soundings/BUFKIT data suggests the precip regime may
trend to more drizzle as the night progresses into Fri morning as
long as the lift continues. Before the taper off in precip
intensity, could see an additional 0.10 to 0.30 tenths of an inch of
rain acrs the eastern half or southeastern half of the fcst area.
Brisk northeast sfc winds of 10-20 MPH overnight to limit any fog
potential worth mentioning in the fcst. After a few lingering
sprinkles in the east Fri morning, will advertise a mostly cloudy
and cool day with north to northeast winds of 10-20 MPH decreasing
late in the day with sfc ridge arrival from the west. But there may
be enough top-down drying subsidence induced breaks Fri afternoon
for some peaks of sunshine. Clearing and cool Fri night into Sat
morning with lows well down in the 30s. With light winds and recent
rainfall, this may be a fog window to watch out for if not enough
sfc layer drying occurs on Fri during the day. If not the fog, then
a robust frost possible.
Saturday and Sunday...Will keep Sat dry and seasonable while the
next upstream cyclone lurks acrs the southwestern plains. but then
several 21z medium range models eject out a lead impulse along with
elevated moisture feed to fuel bands of overrunning rain starting
Sat night some time and increasing in coverage and intensity by
Sunday morning. This lead system battling lingering dry ridge to
the east makes for lower confidence on precip timing Sat night into
Sunday. Depending on cloud cover an precip, Sunday highs may be a
bit aggressive.
Monday through next Wednesday...Differences increase on Monday
between the 12z run ECMWF and GFS in handling the main cyclone
center roll out path. The GFS is far enough to the north where
showers/rain spreads up acrs much of the area later Mon into Mon
night, while the new Euro rolls the low eastward in southern stream
fashion, with it`s associated precip bands missing the CWA just to
the south. With the uncertainty and run-to-run variances, for now
will keep rather high chance POPS in the south and east this
early week period. The active pattern/wave train does not want to
quit, with both the GFS And ECMWF taking more of an aim at the
local area with the next wave by next Wed. A further north
trajectory with this mid week system would mean more of a
thunderstorm threat along with shear patterns supportive of
stronger convection if we get the heating or advection. ..12..
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 627 PM CDT Wed Mar 29 2017
Extended periods of rain, heavy at times will occur for the next 24
hours resulting MVFR/IFR conditions developing this evening and through
Thursday. Breezy east winds will shift to the northeast by midnight
and then the north Thursday as a storm system moves slowly into the
Ohio Valley.
&&
.HYDROLOGY...
Issued at 330 PM CDT Wed Mar 29 2017
Have gone ahead and issued a River Flood Watch for the Iowa River at
Marengo, with early rainfall and routed water from upstream
projections supporting it hitting flood stage there by Sunday. But
with lower confidence in this, again have went the Watch route as
opposed to an early warning. If widespread 1 to near 2 inches of
rainfall do indeed occur acrs much of the local area, a few other
fcst points on area tributaries will have to be watched for rising
near or even above bankfull by this weekend. ..12..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...12
AVIATION...Nichols
HYDROLOGY...12
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
624 PM CDT Wed Mar 29 2017
.Discussion...
Issued at 257 PM CDT WED MAR 29 2017
Main concern this afternoon and evening revolve around severe wx
potential, mainly along and south of the Route 50 corridor. Latest
GOES-16 visible satellite imagery showing a fair amount of
clearing across southern Missouri this hour, with some thinning of
the stratus deck noted further north across our southern portions
of our forecast area. This likely marks the position of a nearly
stalled warm front with upper 50 degree dewpoints noted just to
its south. Per latest SPC RUC analyses, instability generation
has largely been confined to areas south of our area, however fcst
models to include both the RUC and NAM suggest a narrow corridor
of MLCAPE exceeding 500 J/kg extending north into our area later
this afternoon and evening, just south of the warm front. Looking
out west, initial convection now developing over eastern Kansas,
and considering the expectations for the previously mentioned
instability axis extending north in our area, expect this activity
to gradually grow upscale over the next few hours. Wind fields
from various BUFKIT soundings south of Route 50 are impressive,
with stout southeast boundary layer winds overlaid with strong
west-southwest winds centered near 5 kft. This curvature combined
with horizontal vorticity generation along the warm front suggests
an isolated tornado threat will remain with any discrete cells
that develop within the next few hours. As mentioned in previous
forecast updates however, much will remain contingent upon the
degree of destabilization that can occur within the next few
hours. If current RUC and NAM fcsts are accurate, its not
inconceivable to expect mini-supercells south of the KC Metro
with an isolated tornado threat.
Severe convection (if it develops) should congeal more into
multicell structures as the evening hours continue on. After this
exits stage right, deformation band rainfall, now seen western
Kansas and southern Nebraska will begin to shift to the south
before steadily making its way over our area early Thursday
morning. Much of the instability should be gone by then, however
the continuation of an isolated thunder mention appears warranted
given residual MUCAPE aloft. Much if not the entire area should
get involved with this before bulk of precip exits by early
afternoon. This will quickly be followed by increasing heights
aloft and the approach of a shortwave ridge axis which should then
provide for dry weather heading into the early half of the
weekend.
Dry weather won`t last too long as the aforementioned ridge
slides east and the next longwave trough/closed low approaches
Saturday night and Sunday. Again, decent moisture advection in
advance of this feature will help lead to favorable conditions for
precipitation redevelopment by Sunday over much of the lower
Missouri Valley. Overall instability looks to once again be
lacking, however cannot rule out isolated thunder activity with
this system as it slowly marches east. Dry weather looks to return
by Monday afternoon with the next system expected to dive
southeast from the Northern Rockies by midweek, bringing yet
another chance for rainfall to the area as the very active
jetstream pattern continues...
&&
.Aviation...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 624 PM CDT WED MAR 29 2017
Unsettled conditions currently dominate all the terminals on the
Kansas-Missouri border as a broad storm system tracks across the
region. Expect on-again-off-again storms well into the night as
the upper level storm system slowly moves across. Additionally,
as the center of the low moves across CIGs and VIS is expected to
drop into the IFR to LIFR range. Currently, expectations are that
the LIFR to IFR conditions will likely persist through much, if
not all, of the day Thursday.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...32
Aviation...Cutter
Area Forecast Discussion
National Weather Service Northern Indiana
733 PM EDT Wed Mar 29 2017
.SYNOPSIS...
Issued at 330 PM EDT Wed Mar 29 2017
Rain will return to the area late tonight and persist through
Thursday evening. Rainfall amounts will be around an inch for most
locations. This may cause some minor flooding in low lying areas.
Thunderstorms are also possible tomorrow...primarily from late
afternoon through the evening. There is a low chance for severe
storms south of highway 30 during this time. Rain showers continue
on Friday but dry conditions expected over the weekend. Highs on
Thursday will range from the 40s across Michigan to the low 60s
across central Indiana. Highs Friday into the weekend will generally
be in the 50s.
&&
.SHORT TERM...(This Evening through Tonight)
Issued at 330 PM EDT Wed Mar 29 2017
Quiet weather will continue through the evening as ridge axis
downstream of potent upper low folds over our area. Decaying
convection presently over Illinois will struggle to reach our CWA
given persistent E/SE flow until after 06Z tonight and very dry air
aloft noted in 12Z KDTX and KILN soundings. Radar mosaic looks
decent but ceilings are 6-10 kft. A stray sprinkle may survive into
our NW third this evening but best chances for rain will hold off
until after 09Z when nose of southwesterly LLJ and associated theta-
e surge arrive. Clouds will obviously be on the increase overnight
but late arrival of veering winds and good warm/moist air advection
should still allow overnight lows to drop into the upper 30s to low
40s. No concern for mixed precip, even in far NE counties where lows
may touch mid 30s.
&&
.LONG TERM...(Thursday Night through Wednesday)
Issued at 330 PM EDT Wed Mar 29 2017
Rain and severe weather chances tomorrow are primary story for this
forecast package. Another very moist airmass is being drawn north by
this high amplitude southern stream wave. 850mb dewpoints hover
around 10C with PW values around 1.25 inches. Meanwhile, plenty of
dynamical support for UVM with coupled upper jet streaks (for a
time), diffluence aloft, and ample midlevel CVA/height falls. 295K
isentropic fields are correspondingly impressive in the AM WAA wing
with 40kts of sharp cross-isobar flow and mixing ratios climbing
above 6 g/kg. Rain virtually assured...though likely won`t be steady
through the whole day. Suspect a brief break in heavier rain in the
early afternoon...between morning WAA/theta-e surge and evening
arrival of CVA bullseye and associated surface low/convergent
boundary. Storm total QPF anticipated to be around an inch for many
locations. Some minor/nuisance flooding may be possible in typical
low-lying areas given recent wet conditions but ground should be
able to absorb this rain without significant impacts. Latest river
forecasts holding in action stage at worst.
Severe weather threat appears low. As is typically the case in these
events, low to midlevel wind/shear values are more than adequate
with 40kt LLJ but destabilization remains highly questionable.
Latest guidance continues to hold surface warm front over our
southern CWA with ample clouds/precip earlier in the day to limit
surface-based destabilization. If there is a sufficient break after
midday precip, our far southern counties may destabilize enough to
support a few strong storms in the 21-03Z period. However,
amplified/cutoff nature of parent trough suggests a slightly later
arrival of WAA precip (possibly mid-afternoon in eastern zones) that
will leave a very narrow window for sufficient diurnal heating. Hail
would be the main threat although isolated wind and tornadoes cannot
be entirely ruled out if instability axis creeps far enough north.
Certainly worth watching for our southern counties but threat does
appear low at this point.
Sporadic rain showers will continue through Friday as vort lobe and
deformation axis move overhead. Rainfall amounts during this period
will be much lighter and more scattered. Weekend looks much more
pleasant as ridge builds over the region. Not much CAA to speak of,
so high temps will hold generally in the 50s Fri-Sun, near average
for this time of year.
Wet pattern looks to continue into next week with one chance of rain
on Monday and another Wed/Thu. Still plenty of details to iron out
but looks favorable for several chances of decent rainfall. Temps
may be a touch warmer but no significant deviations from climo
expected at this time.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 728 PM EDT Wed Mar 29 2017
VFR conditions look to persist through the evening and most of the
overnight hours but conditions expected to begin deteriorating
toward daybreak. Latest Hires model guidance showing several waves
of pcpn with best chance for restrictions coming toward daybreak
into mid day Thursday with IFR expected. NAM 3km and RAP models
want to bring warm front north a bit faster than spectral and
other hires guidance with boundary to near the US30 corridor by
21z. This would bring warm sector and more mixed conditions into
KFWA late in the period with wind shift to south and strong tsra
chances. Trended winds a bit more southerly but holding onto more
of a model mean at this point. Morning rain and strong easterly
low level flow north of warm front could reinforce cold air and
retard northward movement.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory from 4 AM to 4 PM EDT Thursday for LMZ043-
046.
&&
$$
SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...AGD
AVIATION...Lashley
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Area Forecast Discussion
National Weather Service North Platte NE
345 PM CDT Wed Mar 29 2017
.SHORT TERM...(This evening through Thursday)
Issued at 344 PM CDT Wed Mar 29 2017
The wrap-around rain and drizzle across Ncntl and Swrn Neb should
slowly move east tonight. The forecast uses the HRRR models and RAP
model. This rain is associated with lower level moisture and support
from the upper low across KS.
Most of the short range models show fog forming across the Sandhills
tonight. The RAP model indicates dry air moving in at the 850-500mb
layer and this would promote radiational cooling given the clearing
skies and light winds that are expected to develop tonight. Areas
east of highway 83 remain in the wrap-around clouds overnight.
Clearing is expected from west to east Thursday afternoon across the
Ncntl Neb.
The forecast uses blended guidance plus bias correction. The wet
ground appears to limit lows tonight to a few degrees above the
straight guidance numbers. Highs Thursday rise into the upper 40s
east to around 60 west where mostly sunny skies are expected.
.LONG TERM...(Thursday night through Wednesday)
Issued at 344 PM CDT Wed Mar 29 2017
Friday will be a transition day in between systems, as upper level
ridging briefly builds over the area ahead of the next system that
will dig southeast to near the four corners by Friday evening. By
Friday afternoon clouds will be on the increase, with rain likely
developing across portions of the Panhandle and southwest Nebraska
Friday night. The center of the upper level low pressure system will
very slowly meander it`s way into northern New Mexico Saturday.
Ahead of the system deep southerly flow aloft will draw moisture
northward, with rain once again expected through Saturday from the
western half of Nebraska, southward through Oklahoma and Texas.
Sunday could see a lingering shower or two as the system moves into
the plains from New Mexico and weakens. There is yet another system
that arrives Tuesday into Wednesday, this too appears quite vigorous
with more rain and perhaps some wet snow. All in all beneficial
moisture will continue to accumulate the next several days.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1233 PM CDT Wed Mar 29 2017
Showers will remain in the vicinity of KLBF, KBBW and KONL
through late this afternoon, but thereafter ceilings will
gradually lift into the evening. Dryness in the mid levels may
promote the development of fog at KVTN and other north central
Nebraska terminals overnight as winds go light, but fog should be
absent across southwest Nebraska. Overall forecast confidence is
good due to strong model agreement.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...Taylor
AVIATION...Jacobs
Area Forecast Discussion
National Weather Service Saint Louis MO
325 PM CDT Wed Mar 29 2017
.SHORT TERM... (Through Late Thursday Afternoon)
Issued at 324 PM CDT Wed Mar 29 2017
Primary concern continues to be the potential for a few severe
thunderstorms both tonight and again on Thursday.
Latest high resolution GOES imagery is showing that there has been
some clearing across central and southeast Missouri this afternoon,
though there are stable wave clouds which indicates there is still
an inversion in these areas. With the clearing, should be some mid-
late afternoon heating/mixing which will help the warm front move
northward into southern Missouri. Latest object analysis shows that
MUCAPEs have increased into the 500-1000 J/kg range this afternoon,
and RAP shows these values moving as far north as I-70 during the
evening hours. CAMS including the SPC HRRR show a line of storms
developing by late this afternoon that move into central MO by early
evening, and then progress across the CWA late this evening/
overnight. Still appears that there will be this risk for a few
severe thunderstorms with all hazards possible, primarily across
central and southeast Missouri during the evening.
First round of thunderstorms will move off to the east overnight and
area will set up for a second round of storms on Thursday. NAM/GFS
is showing MUCAPES in the 500-1000 J/kg range with deep layer shear
of 35-50kts. This supports the potential for a few organized severe
storms from mid morning into the afternoon hours. Both the GFS/NAM
are showing low pressure moving across the northern CWA with a cold
front trailing to its south across the CWA during the day. Storms
will develop along and ahead of this front during the day.
Britt
.LONG TERM... (Thursday Night through Next Wednesday)
Issued at 324 PM CDT Wed Mar 29 2017
Severe weather threat should be done by Friday evening as low
pressure moves into Illinois. Guidance continues to print out
precip primarily across northern portions of the area in what looks
to be a well developed deformation zone...much like what`s happening
in western Kansas at this time. The stacked low will move slowly
east-northeast overnight and current thinking is that the def-zone
will linger over northeast Missouri and west central Illinois for a
good portion of the night. It would be a good setup for a big
Spring snow event if temperatures were about 10 degrees colder.
However, overnight lows are not expected to drop below the mid 30s
in northern sections of the area and the low to mid 40s further
south.
Friday and Saturday still look dry with Friday being the cooler of
the two days. There`s some disagreement between the MAV and MET
guidance for Friday`s highs with the MET being about 10 degrees
cooler across the area. Leaning cooler is probably the way to go as
2m temperatures never get out of the 50s on the GFS with what looks
like a pretty persistent strato-cu deck hanging around for a good
portion of the day. Saturday should be a little warmer with the
upper level ridge overhead and low level warm advection trying to
develop ahead of the next low. GFS and ECMWF both print out QPF
over the area on Sunday in the warm advection ahead of the system.
Even through clouds and scattered showers, it should continue to
warm up on Sunday due to the continuing warm advection. The system
moves into the lower Mississippi Valley on Monday spreading more
rain and possible thunderstorms up into Missouri and
Illinois...primarily along and south of I-70. Rain looks to shut
off late Monday night with a brief period of dry weather on Tuesday
before the next system begins the warm advection over the area again
on Wednesday.
Carney
&&
.AVIATION... (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 135 PM CDT Wed Mar 29 2017
Scattered showers with MVFR conditions are expected during the
afternoon. Line of thunderstorms are expected to develop over
western Missouri this afternoon and move across the terminal
during the late afternoon and evening hours with IFR and MVFR
conditions. MVFR and IFR conditions with showers and scattered
thunderstorms will continue through the night. Additional
thunderstorms with MVFR conditions will be possible on Thursday.|
SPECIFICS FOR KSTL: Scattered showers will be possible with MVFR
conditions this afternoon. A line of showers and thunderstorms
with IFR and MVFR conditions. MVFR and IFR conditions with showers
and scattered thunderstorms will continue through the night.
Additional thunderstorms with MVFR conditions will be possible on
Thursday.|
Britt
&&
.PRELIMINARY POINT TEMPS/POPS...
Saint Louis 59 71 45 54 / 90 90 50 10
Quincy 52 61 40 50 / 100 90 80 10
Columbia 55 65 42 54 / 90 80 70 5
Jefferson City 55 66 43 55 / 90 80 60 5
Salem 57 71 47 54 / 80 80 40 20
Farmington 58 70 45 57 / 90 80 40 10
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Memphis TN
825 PM CDT Wed Mar 29 2017
.UPDATE...Evening Update.
&&
.DISCUSSION...
Convective watches are in effect to our South, North and
West...but we should remain in the clear for at least a few more
hours. Saw no compelling reason to change the forecast much this
evening...just adjusted temperatures and dew points a bit.
Storms have developed in Western Arkansas...moving to the North
Northeast while the overall line is shifting slowly East. At their
current pace they wouldn`t reach Eastern Arkansas until Midnight
at the earliest. Will continue to monitor radar and watch closely
for development farther East of the main line. As we approach
midnight a currently weak LLJ will strengthen to around 40-45 kt
helping to develop thunderstorms. The mostly reliable HRRR does
not show explosive development...but I have my doubts.
30
&&
.PREV DISCUSSION... /issued 620 PM CDT Wed Mar 29 2017/
.Two rounds of severe weather expected...
Currently...A strong upper low is located over the southern plains
this afternoon. A warm front is pushing north through the MId-
South and is roughly located from NE Arkansas into West Tennessee
at 19z. Temps are climbing into the lower 80s south of the front
with dewpoints in the lower 60s with some location mixing into the
upper 50s.
Tonight...Expect showers thunderstorms to develop the Arklatex
and across Western Arkansas over the next few hours. This activity
will move east during the evening impacting Eastern Arkansas
mainly after 03z. A potent shortwave rotating around the upper low
will punch into the area late tonight. This feature contains a
8O-90 kt mid level jet and a 40-50 kt low level jet. This low
level jet will feed and increasingly moist and unstable airmass
into the Delta region. Increasing lift associated with this
shortwave will result in the expansion of showers and
thunderstorms later tonight with perhaps maintain or even
increase the storms intensity. Strong mid level lapse rates of
7-8c/km will result in hail being the main threat initially
gradually shifting to a damaging wind threat later tonight as the
storms tend to congeal as they move to the MS River. A few
tornadoes are also possible. The enhanced risk tonight has been
moved to south and west of a Jonesboro Arkansas to Memphis to
Charleston Mississippi line.
Thursday into Thursday night...Expect a large area of showers and
thunderstorms west of the MS River during the morning hours. This
area of storms will be in a weakening stage and eventually lift
northeast of the area by mid-morning. Since the shortwave
rotating around the upper low is more potent late tonight/early
Thursday and the amount of shower and thunderstorm coverage is
potentially greater than previous models runs there is a good deal
of uncertainly concerning the severe weather potential Thursday
afternoon. The 12km and 3km NAM and some versions of the WRF take
an aggressive approach to destabilizing the airmass in the wake of
the morning convection. Meanwhile the GFS/ECMWF have less
destabilization occurring. At this point expect the upper low to
track across Missouri on Thursday with a cold front tracking east
into the Mid-South. Expect thunderstorms to develop along this
front as another potent shortwave rotates around the upper low on
Thursday. The degree of severity will depend on the amount of
destabilization which, as mentioned above, is in question. If
instability to the degree of SBCAPE values in the range of
1500-2500 J/KG can occur then a line discrete supercells with very
large hail and damaging winds will occur along the front. 0-1 km
helicity values over 200 m2/s2 are expected and strong tornadoes
are possible. The EML punching in from the southwest may help
maintain discrete supercells for a longer period of time before
merging into a line. Depending on the amount of destabilization
this line could develop as far west as the Bootheel to Memphis by
18z or further east if more time is needed to destabilize. A
moderate risk continues for most of West Tennessee and North
Mississippi. The line will eventually push into Middle Tennessee
and North Alabama by 8 pm at the latest. Cooler air and some
clearing expecting by Friday morning.
Friday through Saturday...The upper low will lift out on Friday
with some clouds across the north. Temps will be much cooler
across the north with readings in the lower to mid 60s....lower
70s across North Mississippi. By Saturday an upper ridge will
build in with sunshine and temps from about 70 north to 80s south.
Sunday into Monday...Looks unsettled with another upper low moving
through with increasing chances for showers and thunderstorms.
The low is tracking tracking right across the region so any
severe weather risk will probably stay across the south part of
the Mid-South or further south. Confidence too low to add to the
HWO at this time.
Tuesday and Wednesday...Tuesday looks quiet with another system
possible late Wednesday. Just went with small pops for now.
SJM
&&
.AVIATION...00z TAFs
Showers/thunderstorms affecting all sites this period...with
first round reaching JBR and MEM during the first half...and MKL
and TUP during the second. Worst conditions in storms will be IFR
along with strong wind gusts. MEM may see a second round between
sunrise and noon...but coverage warrants VCTS for now. MKL and
TUP run the risk for stronger afternoon storms...which may turn
out to be more severe. Cigs will bounce between VFR and MVFR with
gusty south winds veering southwest behind a passing cold front.
JAB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
756 PM EDT Wed Mar 29 2017
.SHORT TERM...(This evening through Thursday)
Issued at 247 PM EDT WED MAR 29 2017
12Z raobs/latest wv imagery and RAP analysis show a split flow
dominating NAmerica, with upr rdging in both the nrn and srn streams
supporting Hudson Bay hi pres centered over nw Ontario extending a
sfc rdg axis into the wrn Great Lks. Despite the presence of this
rdg axis over Upr MI and some dry llvl air shown on the local 12Z
raobs, quite a bit of hi cld streaming to the ne fm closed srn
branch lo over the srn Plains has overspread the area as winds
aloft shift to the sw ahead of a nrn branch disturbance near the
Cndn border moving e thru the Plains. Pcpn on the ne flank of the
srn branch closed lo has moved as far n as far srn MN/sw WI.
Main fcst concerns in the short term focus on how far n pcpn
associated with the srn branch disturbance wl move late tngt/Thu.
Tngt...The srn branch closed lo is progged to move slowly to the ne,
reaching ern Kansas/wrn Missouri by 12Z Thu while the nrn branch
shrtwv/accompanyin dpva lift ne toward the border of Manitoba/far nw
Ontario. While most of the Upr Lks wl remain under an axis of drier
lo/mid lvl air and larger scale h85-5 qvector dvgc btwn these
disturbances, some hier h85-5 rh on the nrn fringes of the mstr
shield ahead of the srn branch disturbance is fcst to impact the
scentral cwa. But since the dry llvl feed of air out of the slowing
departing Hudson Bay hi pres is fcst to persist, the bulk of the
hier res models show pcpn in the form of sn reaching just s of the
city of Menominee by 12Z Thu. Wl retain some lo chc pops only over
far srn Menominee County toward 12Z. Otrw, the combination of
thickening hi/mid clds and a steady e wind wl limit the diurnal temp
fall.
Thu...The short term guidance shows the closed lo moving to near St
Louis by 00Z Fri, with hier mid lvl mstr influencing the se 1/3 or
so of the cwa on the nrn fringes of area of upr dvgc in rrq of h3
jet max within the confluence zone of the separate branch flows. The
rest of the cwa wl remain under the axis of deep lyr qvector dvgc
btwn the larger scale srn branch forcing influencing WI/Lower MI and
the nrn branch disturbance tracking toward Hudson Bay and remain
dry. Expect a sharp gradient of pops over the scentral, where an
upslope e wind may at least minimize the influence of the llvl
drying associated with the slowly departing Hudson Bay hi pres, as
indicated by the 12Z NAM model. Given the pattern featuring a Hudson
Bay hi pres that favors dry wx for Upr MI, tended toward the drier
scenrios for pops fcst. Although the fcst thermal profiles indicate
this pcpn wl fall mainly as sn, the incrsg late March sun angle that
allows sfc temps to rise at least a couple degrees above 32 wl limit
sn accum potential.
.LONG TERM...(Thursday night through Wednesday)
Issued at 256 PM EDT WED MAR 29 2017
The extended looks to be fairly quiet overall with the main focus on
low pressure sliding to the south of the U.P. Thursday night and
another low pressure trough/disturbance sliding across the area
Saturday into Saturday night. Another scattered precipitation event
is possible for early next week, Tuesday into Wednesday. Otherwise,
expect above normal temperatures through the extended with highs in
the 40s to around 50 and overnight lows in the mid to upper 20s.
Thursday night: An area of low pressure sliding across the mid
Mississippi Valley is progged to lift slowly through the Ohio River
Valley through this time period. At the same time, a Hudson Bay high
pressure system will remain nearly stationary or slide very slowly
off to the east. The northern fringes of the moisture associated
with the low will try to work into the U.P.; however, the northward
extent is expected to be limited as the flow around the high
pressure system will be very dry. The easterly winds will steadily
pump dry air in to offset the approaching moisture. At this point,
will continue pushing the pops down across the south central U.P.
and east along Lake Michigan. If precipitation does occur, it will
mostly likely be in the form of light snow or rain/snow mix. Most of
the sounding looks to be below freezing with some ice crystals in
the layer; however, the lower levels are fairly dry at least through
Thursday evening. The rest of the area is only expected to see an
increase in cloud cover through this time period.
Friday through Saturday night: Drier air and a weak ridge will slide
through the area Friday into Friday night allowing for mostly clear
skies across the U.P. The next chance of maybe a few sprinkles will
be Saturday through Saturday night as a quick moving upper-level
shortwave trough slides through the area. At this point, not
expecting much in the way of precip as moisture will be limited. The
best chance of seeing the sprinles will be over the north half and
over Lake Superior.
Monday night through Wednesday: Several disturbances are progged to
slide near or through the Upper Great Lake region, giving a period
of unsettled weather. This would bring at least intermittent chances
of precipitation to the area and/or increased cloud cover through
this time period. There has been a lot of variance in the models for
this time period, as expected with it being toward the end of the
forecast period. The latest EC/Canadian have most of the area dry
through this time period, while the GFS, as the outlier, tries to
bring a system northward along with scattered rain showers. At this
point, will continue to stick with a blend of the models, painting
only marginal chance of precipitation across the area, mainly for
Tuesday into Wednesday. Stay tuned as there is still plenty of
variability in the models.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 752 PM EDT WED MAR 29 2017
This fcst period wl be dominated by a good deal of high clds that
wl tend to thicken with time at SAW and possibly lower to low end
VFR or high end MVFR by late Thu afternoon. Since the disturbance
responsible for the clds wl remain well to the s of Upr MI, pcpn
and lower vsbys/cigs wl tend to remain s of the TAF sites as
well. Maybe some sprinkles could be possible at SAW late Thu
afternoon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 247 PM EDT WED MAR 29 2017
Ene winds up to 20 to 25 kts will be possible tonight into Fri under
the sharper pres gradient between slowly deparing Hudson Bay hi pres
and a slow moving lo pres that will be drifting from the southern
Plains toward the Lower Great Lakes. Winds for later Fri thru Mon
will be under 20 kts as a weaker pres gradient becomes established
across the western Great Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KC
LONG TERM...KEC
AVIATION...Voss
MARINE...KC
Area Forecast Discussion
National Weather Service Nashville TN
850 PM CDT Wed Mar 29 2017
.UPDATE...
FOR 00Z AVIATION DISCUSSION.
&&
.DISCUSSION...
Our main forecast concern continues to be severe thunderstorms
potential tomorrow into tomorrow evening. This includes potential
for damaging winds, large hail, and tornadoes. A powerful low
pressure system, spinning over OK/KS this afternoon, will move
eastward through Thursday night. As this occurs, gusty south winds
will develop, bringing increasingly unstable air into the region.
Thunderstorms are expected to develop to our west late tonight,
then gradually weaken as they move into Mid TN early Thursday
morning, perhaps beginning around 6 AM. Even with a weakening
trend, there could be a few strong storms with gusty winds and
hail Thursday morning. But, our main concern is for the afternoon
and evening.
The early round of showers and storms could significantly impact
the coverage and scale of severe wx through the rest of the day.
If the early system moves slowly, keeping clouds around and
disrupting the recovery of the boundary layer, then the severe wx
risk will be reduced. Even so, most models still indicate a
significant potential for strong to severe storms by late
Thursday. On the other hand, If the morning system washes out
quickly, and the atmosphere recovers, we could be looking at a
greater severe risk with robust storms developing earlier in the
afternoon and lasting into the evening. This more severe scenario
is definitely not a lock, but it certainly seems reasonable given
the very impressive dynamics with the approaching system. Models
show a powerful 110KT upper jet developing overhead by mid
afternoon with 75KT at 500mb. Deep layer shear values could reach
around 60KT. Cape values are in question, but 1500 j/kg is
certainly attainable. If maximum potential is realized, we could
have several supercells developing by mid afternoon with tornadic
potential. If recovery is a bit more sluggish, storms may be more
consolidated in the late afternoon and evening hours within
clusters, but still damaging and still with some tornado
potential. Given the uncertainties and possibilities, people
should be advised to remain wx aware throughout the day. The trend
into Thursday evening will be consolidation into clusters or a
band of storms that will eventually weaken while moving east
across the Plateau.
Strong wind fields Thursday will create gradient winds of 15-25
mph with some gusts over 40 mph in the afternoon and early
evening. So, we have issued a wind advisory for most areas west of
the Plateau.
Regarding rain and flooding, rainfall amounts will average around
1 inch. Certainly there will be locally heavier downpours, but
given storm movement and questionable depth of moisture, it does
not look like flooding will be a widespread concern.
Some showers will linger into Friday, but the good news is a fine
weekend ahead. Saturday and at least early Sunday look dry with
pleasant, seasonable temperatures. The next system will be moving
in by late Sunday with more showers and thunderstorms, continuing
through Tuesday. This next system does not seem as volatile as
tomorrow`s, but does have at least some severe potential on
Monday.
&&
.AVIATION...
00Z TAF DISCUSSION.
Surface map at 01Z shows a 1002 mb low centered over eastern KS
with a cold front extending southward through the Ark-La-Tex.
Already, the SPC has several watches in place along and west of
the Mississippi Valley. The latest HRRR does bring some cells into
the northwest part of Middle Tennessee just prior to 12Z, so will
leave existing POP`s in place for late tonight. Plus, the SPC does
have the extreme western sliver of the mid state under a marginal
risk of severe storms in its day 1 convective outlook (good
through 12Z). Hourly grids are holding up well so far, so will
leave the forecast alone for now.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from noon to 9 PM CDT Thursday FOR Bedford-
Cheatham-Davidson-Dickson-Giles-Hickman-Houston-Humphreys-
Lawrence-Lewis-Macon-Marshall-Maury-Montgomery-Perry-Robertson-
Rutherford-Smith-Stewart-Sumner-Trousdale-Wayne-Williamson-
Wilson.
&&
$$
DISCUSSION......08
AVIATION........Unger
Area Forecast Discussion
National Weather Service Paducah KY
935 PM CDT Wed Mar 29 2017
.UPDATE...
Issued at 935 PM CDT Wed Mar 29 2017
Thunderstorms continue to increase in coverage and intensity across
the Ozarks this evening. A surface warm front extended from the
southern border counties of Kentucky back westward into the Ozarks
of Missouri. The storms over Missouri are forecast to gradually
develop eastward across the Lower Ohio Valley as the warm front
moves northward overnight. The new 00z nam and rap models indicate
the strongest instability will remain over Missouri the rest of
tonight. Though mucapes will generally remain under 1000 j/kg, shear
will increase as a 500 mb jet streak pivots northeast from the
Arkansas Ozarks. Therefore, an isolated tornado threat will persist
much of the night, mainly in se Missouri.
The 500 mb jet streak of 65 to 75 knots will progress across western
Kentucky on Thursday as diurnally driven storms increase during the
day. Shear and instability parameters suggest the tornado threat
will increase during the day Thursday as the cold front moves east
into our region.
&&
.SHORT TERM...(Tonight through Friday night)
Issued at 239 PM CDT Wed Mar 29 2017
Main story will be severe weather potential late tonight and again
Thursday afternoon and evening. The remainder of the short term
forecast period (Friday & Friday Night) should see slowly decreasing
cloudiness with temperatures slightly below normal.
Initial elevated pre-warm frontal convection has lift out of the
area late this morning and into the afternoon hours.
The next round of convective activity will likely move into extreme
western sections of the WFO PAH forecast area (Carter, Ripley,
Wayne, and Butler Co. in Southeast Missouri), between 8 pm and 9 pm
CDT. However, the severe potential is not likely increase until
closer to midnight for the aforementioned counties. The 12km NAM
and 13km RAP, and in some sense the ESRL HRRR guidance have been
suggesting an instability plume with increased winds aloft over
Southeast Missouri, especially between midnight and 500 am/6 am
CDT/. The primary concern would still be winds and hail during this
time period, but could not rule out embedded circulations (QLCS)
within the line that may produce a brief tornado. Although included
in the SPC Day 1 Severe Weather Outlook for severe potential, am
concerned that Southwest Illinois could see some severe potential as
well before daybreak. Will wait and see what happens with later
outlooks from SPC.
The convective activity during the morning hours may contaminate and
slow the progress of the next plume of instability and shear for the
WFO PAH forecast area, especially the western half of the CWA. At
this time, have focused any mention of Severe Thunderstorm to West
Kentucky, Southwest Indiana, and Southwest Illinois for Thursday
afternoon and evening, mainly between noon and 8 pm CDT. All modes
of severe weather, hail, damaging winds, and tornadoes, as well has
heavy rain will be likely. Greatest concern for some stronger
tornadoes will be in southern sections of West Kentucky, outlooked
by SPC as Moderate Risk in the Day 2 Severe Weather Outlook.
.LONG TERM...(Saturday through Wednesday)
Issued at 239 PM CDT Wed Mar 29 2017
Moderate forecast confidence exists through the extended portion
of the forecast, as we remain in a very active pattern.
We will be in a progressive zonal flow aloft with two strong storm
systems moving east northeast through or region. The first storm
system will take a more southern track, with the upper low passing
just to our south over or right through our region. The 12Z models
have some differing ideas on how fast we may begin to see
precipitation with the system, but the consensus emphasizes Sunday
night and Monday for widespread showers and storms.
The 12Z GFS brings showers into the region late Saturday night
into Sunday, while the ECMWF keeps the area mostly dry for that
period. Likewise, the GFS lingers QPF into Tuesday, where the
ECMWF and CMC do not. Bottom line is we will have PoPs over about
a 72 hour period, but the main action will be Sunday night through
Monday evening. With the upper low passing over or to the south
of the region, organized severe weather is not likely with this
system. The cold core aloft could result in some small hail, but
the wind fields will not be conducive to organized severe storms.
The second storm system is expected to track north of our area,
potentially situating us in a better position for some more severe
weather. There is some variability in the timing of this system,
but it should be a bit more of a quick hitter sometime Wednesday
through Thursday. Wind fields should be more supportive of
organized severe storms, depending on the amount of moisture and
instability available.
Temperatures will remain on the mild side through the extended
forecast.
There are some signs of a pattern shift late next week, as
troughing develops over the northeast Pacific. This will likely
lead to downstream ridging over the west coast, and potentially
more of a northwest flow over our region. Of course that would
make Gulf input less readily available, and hopefully lead to a
less active convective regime. We will see.
&&
.AVIATION...
Issued at 630 PM CDT Wed Mar 29 2017
VFR Cigs this evening, primarily, will yield to MVFR bases as the
first wave of convection moves in toward midnight. Another late
night wave may offer more restrictions, to both CIGS and VSBYS, as
atmosphere moistens/destabilizes. A brief early to mid morning
pause, will then be followed by the potentially strongest storms
for the PM hours. Winds really get cranking by then too, so these
were the additions to the inherited forecast, esp for the planning
period.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...MY