Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/11/20
Area Forecast Discussion
National Weather Service Denver/Boulder CO
817 PM MDT Sun May 10 2020
.UPDATE...
Issued at 816 PM MDT Sun May 10 2020
Not much to change at this point. Any shower activity over the
higher terrain will likely hold off until around sunrise. Across
the plains there is a well developed Denver Cyclone southeast of
DIA. Lower level clouds have been increasing across nrn areas of
the plains so will increase cloud cover overnight.
&&
.SHORT TERM...(This evening through Monday)
Issued at 250 PM MDT Sun May 10 2020
Colorado remains under a moderate Northwest flow pattern this
afternoon with weak ridge aloft over the eastern Great Basin.
Already seeing some increase in high level moisture streaming
downstream from the ridge. There is a weak system moving into the
western Great Basin and desert southwest with some moisture and
instability with quite a bit of thunderstorm activity over
Arizona and some sneaking into southwest Colorado. Could see a
late day shower over southern portions of our mountains but still
moisture and instability are marginal at best.
The better moisture and instability will move into the mountains
later tonight with some weak QG ascent and will have the higher
pops then with even a few thunderstorms possible in advance of
weak trof. Across the plains, southeast low level flow will
develop with some possible stratus later tonight over the far
plains and some increase in low level moisture. Surface dewpoints
expected to rise back into the 40 by later in the day on Monday.
Given higher cloud cover on Monday, temperatures will be cooler
and instability limited for much of the day with very little in
the way of surface based CAPE, except from 500-1200j/kg over the
Palmer Divide if you believe the RAP/NAM higher CAPE solutions.
Suspect that is somewhat overdone as RAP showing dewpoints close
to 50 (highly doubtful). Best chance for stronger thunderstorms or
low end severe may be over the mountains where the best
instability will reside with CAPE values of 500-1000j/kg. PW
values also expected to range from 1/2 to 3/4 of an inch by Monday
afternoon. Will have basically chance pops over the plains during
the afternoon.
.LONG TERM...(Monday night through Sunday)
Issued at 250 PM MDT Sun May 10 2020
The long term will be dominated by several shortwave troughs
rounding a semi-permanent and nearly stationary upper low near
Hudson Bay.
Widespread showers across the forecast area and isolated
thunderstorms near the higher terrain will be ongoing early Monday
evening. Activity will be waning from west to east through the
night, however QG motion will remain slightly upward and
southeasterly surface winds into the plains will keep PW values
elevated to near the 90th percentile. Low clouds and patchy fog
will likely spread west over the eastern plains, possibly as far
as into the urban corridor.
On Tuesday, flow aloft will transition to a drier and warmer west-
southwesterly direction, with increasing wind speed as another
shortwave trough crosses the Northern Rockies. The mountains will
experience these increased speeds, for a breezy day. At the
surface, a surface high over the Great Plains will keep in breezy
southeasterly moist winds over the eastern CO plains, however a
surface trough will be forming along the foothills and possibly
into the urban corridor. Models disagree on this position, but
a dry line will form at the meeting of the two airmasses, and may
be able to fire off some showers and storms Tuesday afternoon. GFS
has the trough further east, keeping the chance of storms further
east with more stable conditions across the urban corridor. NAM
has it further west, giving more of a chance of storms starting at
the urban corridor, with more instability, however it keeps it
capped as the cooler lower airmass in easterly flow. Will have a
slight chance of storms mainly over the Cheyenne and Palmer Ridges
where they would get out of the lower stable airmass, then have a
higher chance out east in the evening.
Warmer temperatures and drier air will push in Wednesday in west-
southwesterly flow. This may increase fire weather concerns over
South Park, but fuels are likely close to green up, decreasing the
concern. Another shortwave crossing over the Great Basin will move
across northern Colorado, but not likely until later. So will have
just a slightly chance of showers and storms mainly north of I76
during the afternoon, with chances increasing across most of the
forecast area in the evening as a cold front pushes south, keeping
chances of showers through midnight.
Thursday will be a few degrees cooler and another day of scattered
to numerous showers and thunderstorms as yet another shortwave
from the Great Basin crosses the state - late again so that
showers will likely last overnight and even into Friday morning.
Residual moisture in the area and another shortwave trough moving
across the Northern Rockies will keep showers in the forecast
through Friday. Models are diverging on the strength of this
trough and how deep it digs south. Will keep a chance of showers
and thunder through Saturday evening for this. After this, models
show a ridge moving into the area for a warmer and drier Sunday in
southwest flow. The ridge is being pushed east by a deepening
large system off the Pacific Coast, slated to move slowly into the
Great Basin by Wednesday, which will bring much warmer
temperatures for the beginning of next week in south-southwest
flow. Both the EC and GFS are showing 700 mb temperatures of 14-16
degrees C by Tuesday, which would translate into highs in the
upper 80s for the plains, in the 60s for much of the mountains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 816 PM MDT Sun May 10 2020
Denver Cyclone was southeast of DIA as winds have maintained a more
NNE direction early this evening. Models have a poor handle on the
location of this low. If this low stays nearly stationary winds
at DIA may maintain a more northeast component overnight. Also
there is a lower level cloud deck down to 7000 ft which has
developed along and north of a Fort Collins to Fort Morgan line.
Some of these clouds could affect the airport by midnight if the
low level flow remains more northeast.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...RPK
SHORT TERM...Entrekin
LONG TERM...Kriederman
AVIATION...RPK
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1153 PM EDT Sun May 10 2020
.AVIATION...
Lower tropospheric cold air advection acted upon a slow to move low-
mid deformation to allow for snow to mix in at all of the Metro
Detroit taf sites. Latest model data has this ending by or shortly
after 06Z. Low level cold advection supports MVFR stratus
development. Model soundings suggest some potential for trapped
moisture to mix out late tonight, but pattern recognition suggests
MVFR cigs persisting through the morning. VFR ceilings late morning
into the afternoon. Northwest winds are expected Monday afternoon in
the 15 to 25 knot range.
For DTW...Low level cold advection will support saturation and MVFR
cloud through Monday morning. VFR cigs Monday afternoon.
DTW THRESHOLD PROBABILITIES...
* High for ceilings at or below 5000 ft tonight
&&
.PREV DISCUSSION...
Issued at 1045 PM EDT Sun May 10 2020
UPDATE...
Precipitation type has changed over completely to snow in the
highlands here of northern Oakland County this evening. Combination
of steady near surface cooling T 33/Td 32 and wet bulbing with
persistent moderate precipitation rates has allowed for all snow at
the office with bright banding lighting up the radar. Gauging the
progression of precipitation within the stretching deformation
axis/occlusion or lack thereof, steady southward progression of the
cold air the remainder of the evening will allow most locations to
witness snowflakes before precipitation ends. A very quick snowfall
accumulation has been observed in grassy areas/on elevated surfaces
here at the office due to a period of large sticky aggregates. With
warm ground temperatures not expecting much issues on roadways across
area, but an opportunity certainly exists to witness a measurable
snow accumulation here on May 10th. The pivot of the band is largely
on schedule with latest HRRR runs, expect this precipitation to hang
around the area through 06Z before quickly waning.
PREV DISCUSSION...
Issued at 359 PM EDT Sun May 10 2020
DISCUSSION...
The center of the surface low will shortly drift just east of
Detroit forcing the cold front east and south of the area. This will
bring an end to the convective portion of the system as now the
active deformation axis becomes positioned over SE MI. The upper
level circulation will catch up to the surface reflection while the
deformation band sets up over northern portions of the CWA which
will add mid level support to this pre-existing forcing. Models show
a flare up of 700-850mb fgen right overhead after 00Z which then
lasts several hours into the night while pivoting over the area on
its eventual track eastward. This will keep showers likely through
about midnight before the entire system gets far enough east to no
longer be a factor locally. Even as winds become northwesterly and
introduce cold air advection to the back of the system, shallow
moisture depths mainly between 0C (900mb) and -10C (775mb) will
minimize chances to change over to a frozen ptype although can`t
rule out a few wet snowflakes mixing in.
By Monday morning, northerly flow cold advection pattern will bring
a return of 850mb temps down around -7C. This will result in steep
low level lapse rates as surface temps rise into the mid/upper 40s.
There will be enough residual moisture to produce a healthy deck of
clouds and possibly even a period of flurries as a sheared axis of
vorticity draped north of the Great Lakes gets pulled down through
lower MI.
Broad area of high pressure across the Plains will then slide south
and east across the Great Lakes by Monday evening. Winds will weaken
though remain primarily northerly, and a much drier airmass will
fill in across the state. The cold resident airmass, clear skies and
light winds will once again allow min temps to drop into the upper
20s Monday night into Tuesday morning. A freeze warning will likely
be needed for at least a portion of SE MI.
High pressure will then center itself over the region on Tuesday
while upper level ridge begins to slide east into the Plains.
Longwave pattern overall will deamplify as the strongest portion of
the jet races off the east coast. The more westerly flow overhead
will begin to moderate the airmass as warm advection sets in.
Combined with a good deal of sun and high sun angle, we should see a
nice jump in high temps into the mid 50s. The ridge axis will slide
through the region Wednesday bringing increasingly warmer air into
the region as we fall solidly into the southwest flow regime. This
will also mark the start of a potentially active stretch of weather
with GFS and EURO both hinting at a series of shortwaves lifting
through the region in the Thursday to Saturday timeframe.
MARINE...
Strong winds return this evening as a low pressure system advances
eastward. A warm front currently bisecting lower Michigan will keep
winds W/SW on the warm (south) side and NE winds on the cold (north)
side early tonight. Additionally, a cold front associated with the
low will force gusty showers through the southern lakes prior to
midnight. Gusts to 35 knots will be possible at times. A broad NW
wind shift will occur behind the low overnight with a potent surface
pressure gradient keeping winds elevated overnight. Small Craft
Advisories are already in effect with expected gusts in the 20-25
knot range as 925 mb height falls phase with increasing LLJ winds.
Will need to monitor forecast trends to see if Lake St Clair and
Lake Erie need to be added for the 10 pm marine update. Dry
advection makes for a rain-free start to Monday before scattered
showers develop during the afternoon. Diffuse high pressure arises
on Tuesday with quiet weather preceding a stronger ridge arriving
on Wednesday which will initiate a warming trend through the end of
the week.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Lakeshore Flood Advisory until 4 PM EDT Monday for MIZ049-055-063.
Lake Huron...Small Craft Advisory until 4 PM EDT Monday for LHZ421-441>443.
Lake St Clair...Small Craft Advisory until 4 PM EDT Monday for LCZ460.
Michigan waters of Lake Erie...Small Craft Advisory until 4 PM EDT Monday for LEZ444.
&&
$$
AVIATION.....CB
UPDATE.......CB
DISCUSSION...DRK
MARINE.......KK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Green Bay WI
603 PM CDT Sun May 10 2020
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Monday
Issued at 238 PM CDT Sun May 10 2020
The latest RAP analysis and satellite/radar imagery show low
pressure moving across southern Lower Michigan early this
afternoon. Behind the low, ample cloud cover and chilly temps
prevail across northeast Wisconsin, with readings ranging from the
middle 30s to the middle 40s. Plenty of cloud cover exists
upstream over and north of Lake Superior, so do not expect much
clearing this afternoon. Light precip, however, is diminishing
from north to south, but still some light rain or drizzle
appearing from Kewaunee to Stevens Point. With a cool airmass in
place and potential for clearing skies tonight, forecast concerns
mainly revolve around the potential for freezing temperatures.
Tonight...As low pressure pulls away, high pressure positioned
over the Plains will edge ever so slightly towards the western
Great Lakes. North winds will therefore continue, and will likely
persist at most locations to prevent decoupling. Cloud cover will
also be an issue, as models indicate that a push of drier air will
not occur until very late tonight. Will side with guidance
slightly warmer than the NationalBlend, which will place lows
ranging from the middle 20s to lower 30s. Forecast lows remain
below freezing at most locations, so will issue a freeze warning
for central to northeast Wisconsin where the growing season has
started.
Monday...Northwest winds will bring another dry airmass into the
state. Although some high based diurnal cumulus will pop with the
heat of the day, skies will remain mostly clear to partly cloudy
which should help temps rebound into the middle 40s to middle 50s.
.LONG TERM...Monday Night Through Sunday
Issued at 238 PM CDT Sun May 10 2020
Potential frost/freeze headlines and elevated fire weather
conditions will be the concern into Tuesday, followed by a milder
and somewhat wetter pattern for the rest of the week.
A weak cold front is expected to move through the region Monday
night, but skies will remain clear to partly cloudy. Lowered
the blended forecast temperatures a bit, especially in the typical
cold spots of north-central WI. A hard freeze looks like a good
bet, especially northwest of the Fox Valley/lakeshore areas.
Expect a slight moderation in temperatures on Tuesday, with highs
in the 50s, and another day of very low relative humidity in the
sandy soil regions. Dry conditions should persist through Tuesday
night, but low temperatures should not be as cold due to WAA and
increasing high clouds late. Even so, suspect we will still need
at least frost advisory headlines.
Strong return flow is expected to develop Wednesday afternoon and
night, as the surface high shifts into the eastern Great Lakes
and a 30-40 knot low-level jet develops. This will bring a swath
of showers through the forecast area. The showers should diminish
somewhat overnight as the low-level jet veers west.
Models offer differing solutions on Thursday and Thursday night.
The GFS is farther north with a surface low and associated warm
front, and brings significant QPF to most of the region Thursday
afternoon and evening. The ECMWF is farther south and much drier,
with showers mainly impacting our southeast counties. Due to the
uncertainty, we stayed close to the blended model pops during
this period. Milder temperatures in the 60s are anticipated,
though precipitation trends will have an impact on this.
Friday looks like the best bet for a dry day late in the week,
as weak high pressure arrives. Could see a few of our typical
warm spots reach into the lower 70s.
Seasonal temperatures and small precipitation chances are
anticipated for the weekend, with high temperatures reaching
65 to 70 degrees away from Lake Michigan.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 542 PM CDT Sun May 10 2020
Clouds will gradually diminish from north to south late this
evening as drier air filters in from Canada. The mid cloud deck
around 4-5kft will lift through late this evening allowing all
locations to remain VFR. This trend is expected through the
remainder of the TAf period with good flying conditions expected.
&&
.FIRE WEATHER...
Issued at 238 PM CDT Sun May 10 2020
Elevated fire weather conditions are expected on Monday and
Tuesday. Relative humidities should drop into the 15 to 25 percent
range in the sandy soil regions both days, but winds should only
be moderate from the west-northwest, with gusts to 15 to 20 mph.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 2 AM to 8 AM CDT Monday for WIZ020-022-030-
031-035>040-045-048>050-073-074.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......Cooley
FIRE WEATHER...Kieckbusch
Area Forecast Discussion
National Weather Service Louisville KY
921 PM EDT Sun May 10 2020
.Forecast Update...
Issued at 919 PM EDT Sun May 10 2020
Surface front and associated showers have exited our CWA as
satellite shows mostly clear skies over the area. Winds are still
gusting into the 25-30mph range but are expected to decrease within
the next couple of hours. Have updated the near term grids and will
also update the HWO to remove any mention of hazardous weather.
Issued at 701 PM EDT Sun May 10 2020
Latest surface analysis shows the surface low centered over Lake
Erie with the cold extending SW through OH and bisecting LMK`s CWA,
lying over FFT through BWG. Radar has shown some activity popping up
over the Bowling Green area where the environment is characterized
by meager SBCAPE (~200 J/kg) and respectable DCAPE (~700 J/kg).
Surface heating has resulted in steep low level lapse rates, which
has been able to mix down upper level energy and produce strong
surface winds with gusts in the 30-35mph range. Not expecting these
showers over BWG to do much as RAP soundings show slight warming
between 850-700mb, which should provide enough capping to quell any
vertical development. With that being said, wouldn`t rule out a
rogue gust in the 40mph range as the larger showers collapse.
Farther north over and east of the Bluegrass, showers and
dissipating thunderstorms continue to move eastward. Had a couple
reports of pea size hail in Fayette County with one report of half
inch hail over Lexington. Since then, cells and associated lightning
have decreased. Expect this trend to continue as the cold front
pushes eastward out of our area by later this evening.
Have updated forecast grids to make mention of showers and slight
chance TS over BWG area. Also made small adjustments to sky and near-
term grids. Otherwise, forecast is on track with winds decreasing
within a couple hours after sunset. Updated products forthcoming.
&&
.Short Term...(This evening through Monday)
Issued at 247 PM EDT Sun May 10 2020
Have been watching a line of showers and thunderstorms form across
southern Indiana ahead of a cold front. This line is expected to
continue moving east and expanding over the next few hours. CAPE is
over 250 J/kg with DCAPE values near 500 J/kg. This is due to the
steep low level lapse rates allowing elevated wind energy to make it
to the ground. A couple of SPS`s has been issued as we observe this
taking place. Bowman Field in Louisville has already measured a wind
gust of 42 mph. Winds this strong can knock loose tree limbs and
unsecured items, but with that being said, not expecting much severe
weather. Most of the wind gusts in the area have been closer to 30
mph.
Tonight, the cold front makes its way through Kentucky allowing
surface high pressure to occupy the Ohio Valley. This will provide
clear skies tonight, but temperatures won`t drop like one might
expect because 5-10 mph winds will keep the atmosphere more mixed.
With radiative cooling limited, expect lows in the mid to upper 30s
by morning.
Tomorrow expect lots of sunshine. Winds remain from the northwest as
the region remains in front of upper ridging and east of the surface
high. High temperatures will probably be limited to the 50s by some
afternoon cloud cover and the cool northerly breeze.
.Long Term...(Monday night through Sunday)
Issued at 243 PM EDT Sun May 10 2020
The cold upper trough that has been playing a role in our chilly
weather recently will exit early in the long term and be replaced by
weak ridging for much of the week...followed by zonal flow for the
weekend.
Still, we`ll have one more cold morning Tuesday with lows mostly in
the 35 to 40 degree range. A dome of cold Canadian high pressure
will be just about overhead at sunrise Tuesday with light winds.
High clouds will begin to stream in, but there may be enough low
level moisture to support the idea of some frost in the Blue Grass.
Tuesday an upper wave over Texas will spread more clouds into our
skies with a chance of rain moving in as the wave proceeds to the
Lower Mississippi Valley Tuesday night into Wednesday. The upper
ridge should then become more assertive Wednesday night through
Thursday night, resulting in lower chances of rain.
Flatter upper flow Friday through Sunday makes for a more difficult
forecast. General pattern of small waves moving through the flow
aloft plus surface high pressure off the southeast coast suggests
warmer and more humid conditions (highs in the 80s, dew points in
the 60s) with occasional shower and thunderstorm chances.
&&
.Aviation...(00Z TAF Issuance)
Issued at 735 PM EDT SUN May 10 2020
As per regional observations, the surface cold front is currently
lying NE-SW roughly over FFT to BWG. Satellite imagery shows a line
of agitated cumulus along and slightly ahead of the front while
radar reveals these to only be showers at this point. Tight pressure
gradient will see continued strong winds out of the WNW with gusts
around 25-30kt beginning to decrease a couple hours after sunset.
VFR conditions are expected throughout the TAF cycle, but winds will
pick up again Monday late morning out of the WNW with gusts into the
upper teens to around 20kt with a diurnal cu field popping up
resulting in a FL050 CIG.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...CG
Short Term...KDW
Long Term...13
Aviation...CG
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
636 PM CDT Sun May 10 2020
.SHORT TERM...(This evening through Monday night)
Issued at 218 PM CDT Sun May 10 2020
Visible imagery show extensive cloud cover across the area this
afternoon, with diurnal enhancement of CU/TCU thanks to lingering
cyclonic flow and good lapse rates with the upper cold pool
overhead. The back edge to the most widespread shower activity is
collocated with the back edge of the upper PV anomaly, per the RAP
2.0 PVU analysis. This will continue to push south this
afternoon, taking showers out of the area as max daytime heating
also winds down. We`ll see clouds stick around into the evening,
but subsidence and increased low level ridging should work to
scour them out as the night progresses. Near and below freezing
temperatures look like a good bet overnight, so kept the Freeze
Warning up for areas where sufficient green-up has occurred. The
metro area should escape the coolest temperatures thanks to the
UHI, but outlying areas could certainly get down into the upper
20s. Monday will be unseasonably cool but dry as northwest upper
flow remains in place across the area. Monday night will bring
another night of sub-freezing temperatures to most of the area,
with another Freeze Warning looking all but certain for the same
areas.
.LONG TERM...(Tuesday through Sunday)
Issued at 218 PM CDT Sun May 10 2020
Guidance continues to show the large scale mid/upper flow de-
amplifying across the CONUS by midweek, with an upper trough
approaching the west coast by week`s end. The main system of
interest for our area looks to come midweek, when the initial
strong return flow and warm advection sets up across the region.
Widespread showers and a few thunderstorms can be expected with a
broad area of warm advection and a somewhat muted moisture return
per 850 mb theta-e forecasts. Better moisture/instability will be
to our south, and better isentropic ascent will be to our north,
so we could be split to some extent by where the heaviest
precipitation occurs, but it still looks like we`ll have enough
going on to get some precipitation, so high PoPs look like a safe
bet Wednesday into Wednesday night. After that more spread becomes
apparent in the guidance, which isn`t surprising given the more
zonal flow and greater potential for timing and amplitude
differences in the solutions. Stuck close to the consensus NBM
guidance for the balance of the forecast, which results in a few
periods of chance PoPs from Thursday into the weekend, but with
generally moderating temperatures (back near or a bit above
normal).
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 636 PM CDT Sun May 10 2020
Overcast clouds with a few breaks around 6000 feet AGL will
gradually move out of the area and dissipate. Clouds have largely
become stratocu and will take a little while longer to dissipate
or depart amidst lingering cyclonic flow, but most areas should
be scattering out from northwest to southeast between 06z-12z.
Only some scattered high clouds are expected Monday, but the main
concern will be northwest winds and to what extent they gust. Best
chance for gusts near 20 knots Monday afternoon will be in
western and south central MN.
KMSP... VFR conditions throughout. Gusts will taper off this
evening, though there may be some gusts to 16 kts or so through
02Z. Northwest flow persists through Monday, with more gusts up to
16 knots in the afternoon. After the clouds around 6k-7k feet AGL
depart late tonight, there should only be some scattered clouds
Monday.
/OUTLOOK FOR KMSP/
TUE...VFR. Wind NW 5 kts.
WED...VFR. Chc of -RA/MVFR cigs. Wind SE 10-15G25 kts.
THU...VFR. Wind SW 5-10 kts becoming NW.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Freeze Warning from 2 AM to 8 AM CDT Monday for WIZ023>028.
MN...Freeze Warning from 2 AM to 8 AM CDT Monday for MNZ056>070-
073>078-082>085-091>093.
&&
$$
SHORT TERM...
LONG TERM...
AVIATION...TDK
Area Forecast Discussion
National Weather Service Marquette MI
635 PM EDT Sun May 10 2020
.SHORT TERM...(This evening through Monday)
Issued at 311 PM EDT SUN MAY 10 2020
The overall large-scale pattern of negatively tilted western U.S.
ridging and broad eastern U.S. troughing continues tonight and
tomorrow. Radar this afternoon shows scattered returns over the
north wind snow belts, which have been observed to be a mix of snow
showers and drizzle. This makes sense given HRRR and NAM profiles
showing saturation to around -8 to -10 C resulting in the heavier
convective cells producing snow and the weaker ones mostly producing
drizzle. The last several runs of the HRRR have indicated that this
low-level moisture will dry up after about 21-22z so have the chance
and slight chance POPs ending around then.
Tonight the next round of colder air aloft moves in, dropping 850 mb
temps from about -7 C where they are now to around -12 C by early
tomorrow morning. The short wave that ushers in this cold shot is
rather weak, meaning there won`t be much wind aloft to mix down.
Chances for renewed lake-effect showers look very low since the
saturated layer is pretty thin and there is very dry air just above
it. But it`s not impossible that there could be a few rogue
flurries in the NNW wind LES belts tomorrow morning.
Any lingering lake-effect clouds will clear out by mid to late
morning. Despite the air aloft being colder tomorrow than today,
temps tomorrow should actually be warmer thanks to the sunshine.
Model profiles show mixing to at least 4000 feet and possibly even
600 feet or more (about 750 mb) which gets highs up to the mid 40s
west and south. East and near Lake Superior highs will remain stuck
in the 30s with onshore NW flow persisting through the day, but at
least it won`t feel quite as cold with the bright May sun. This deep
mixing plus the aforementioned very dry air aloft means the other
thing to watch tomorrow will be just how dry it gets. For dew
points, assumed mixing to about 6000 feet over the west which from
NAM and GFS profiles would result in dew points falling into the low
single digits. This translates to RH values between 15 and 20% over
the west in the afternoon and 20-25% central and east. Wind,
although not terribly strong, could still gust to 15-20 mph at times
thanks to the mixing being so deep. Temps only being in the 40s will
severely limit the fire weather potential despite these numbers, but
can`t completely rule out any fire weather concern with those RH
numbers.
.LONG TERM...(Monday night through Sunday)
Issued at 417 PM EDT SUN MAY 10 2020
Medium range model runs over the last 24hrs do not show any
significant changes in the expected evolution of the pattern across
N America. Unseasonably cold conditions are still underway across
the Great Lakes region under a highly amplified pattern. This
pattern features a sharply amplified ridge along the w coast of N
America, extending n into the Arctic, with positive height anomalies
linking to another positive height anomaly center over the N
Atlantic in the vcnty of southern Greenland and Iceland. This
continues to force deep troffing into se Canada, the Great Lakes
region and New England, and thus the cold conditions. Over the next
few days, a shortwave off the W Coast will cut into the western
ridge over the western U.S., and positive height anomalies will
shift n and strengthen/consolidate over the Arctic Ocean where 500mb
height anomalies will increase to around 350m. This will work to
suppress heights farther s across much of Canada this week. Combined
with the loss of the western ridge, this spells a transition to a
more zonally oriented flow across the northern Lower 48, and thus,
warmer conditions are on the way for the Upper Lakes. Conditions
will remain unseasonably cool thru Mon, then temps will gradually
increase, reaching more typical mid May readings by late in the
upcoming week. Normal mid May high temps across Upper MI are in the
60s, coolest closer to the Great Lakes. Farther down the line during
the week of May 17, ensembles still indicate development of troffing
into the western Lower 48 while some degree of ridging is noted to
the n in western Canada. Which feature is more amplified will
determine the temp outcome across Upper MI, but right now, it looks
like temps during the week of May 17 will generally be around the
mid to late May normals, potentially leaning above normal more days
than not during that week, and early in that week, there could be a
couple of warm days. As for pcpn, the transition to a more zonally
oriented flow regime over the next few days will be a dry one. Next
chc of meaningful pcpn will arrive late Wed/Thu when some of the
shortwave energy cutting thru the western ridge streaks e to the
Upper Lakes. Heading thru the weekend, potential of pcpn is much
more uncertain.
Beginning Mon night/Tue...models are in good agreement showing a
vigorous vort max swiping far northern and eastern Lake Superior.
Given the lack of moisture and with the fcst area situated on the
right side of the vort track, don`t expect any synoptic pcpn with
this feature. Wave will brush the area with one last reinforcing
shot of colder air, possibly dropping 850mb temps to -12C.
Combination of the vigorous wave, cold air and deeper moisture
profile closer to the vort max track may be sufficient for some lake
enhanced -shsn into the eastern fcst area during the night. To the
w, dry air and mostly clear skies will result in another chilly
night for mid May. Traditional interior cold spots may slip blo 20F.
The colder air arriving Mon night will likely support stratocu
expansion for a time after sunrise on Tue, mainly over the e half of
the fcst area as daytime heating works on the moisture provided by
the lake. Will be short-lived as the daytime heating then goes on to
mix out the moisture as drier air is mixed down. Thus, expect a
trend to sunny skies in those areas that see clouds in the morning.
Speaking of the dry air, mix down potential of dry air will cause
dwpts to fall in the aftn, probably to around 5F, if not lower, in
the interior w half. With high temps pushing lwr 50s in that area
(which will be the warmest across the fcst area), RH will fall to
around 15pct. Combined with aftn winds gusting to 15-20mph, it will
be a day of increased wildfire potential even though it will be
cool. Although RH won`t be as low e, dropping to around 25pct,
wildfire potential will be increased there as well. High temps will
be lowest e near Lake Superior. Readings there will not get out of
the 30s.
High pres ridge over the area Tue evening will shift e during the
night. So, the night will start quiet/calm and clear. As the ridge
shifts e, expect some increase in winds w and n overnight. Also,
high clouds will start to increase, at least over the w overnight,
well in advance of shortwave approaching the Northern Plains. In the
interior, clear skies/calm conditions will support one more
unseasonably cold night. Traditional cold spots may drop into the
teens.
The transition to a more zonal pattern will bring a couple of
shortwaves eastward, affecting the area late Wed/Thu. 12z medium
range models maintain a consistent picture with the model runs
viewed 24hrs ago. In response to the approaching waves,
strengthening waa/isentropic ascent and moisture advection will
likely spread rain into Upper MI late Wed into Thu. There are still
some timing differences among the models, but that difference has
narrowed. Overall, signal is there for at least a widespread light
rain late Wed into Thu. GFS is stronger with the second shortwave,
resulting in an increase in rain Thu evening. Leaned fcst toward the
more consistent ECMWF which is weaker with the second wave and thus
quicker drying things out for Thu night.
Fri thru the weekend, no consistent model trends have emerged,
except for a drier signal on Fri due to increased agreement for sfc
high pres to pass over the Upper Lakes. Based on recent days medium
range guidance, there will be a potential of -shra at some point
over the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 635 PM EDT SUN MAY 10 2020
Will be VFR conditions for most of the forecast period. There could
still be a brief MVFR condition at the beginning of this forecast
period, but do not have that in there as will be very brief indeed.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 311 PM EDT SUN MAY 10 2020
NW winds around 15 kts west half and 25 kts east half this evening
will veer to NNE tonight but remain around 20 kts give or take.
Winds then back to SW on the west half and relax to around 15 kts
Monday. On the east half winds veer to NW but stay around 20-25 kts.
Except for another brief period of winds up to 25 kts on the east
half late Monday night into early Tuesday morning, winds across the
lake are expected to stay at or below 20 kts through the end of the
week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...RJC
LONG TERM...Rolfson
AVIATION...07
MARINE...RJC
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Morristown TN
1020 PM EDT Sun May 10 2020
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
A cold front will be moving through the area over the next few
hours. Showers associated with the front will affect areas north
of I-40 tonight, with light QPF amounts. The front should clear
the area by 09Z. Overall, the forecast is on track and only a few
small tweaks will be needed, mainly to hourly temps and dewpoints.
DGS
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR conditions are forecast through the period, but broken to
overcast clouds around 5kft will be moving in at TRI and TYS
overnight. A few showers may occur in the vicinity of TRI. SW
winds this evening will shift to W-NW as a cold front moves
through, and winds will be in the 8-12 kt range through tomorrow,
gusting at times to 20-25 kts at TRI.
DGS
&&
.PREV DISCUSSION...
/ISSUED 329 PM EDT Sun May 10 2020/
SHORT TERM (This Afternoon through Sunday)...
Another day of below average temperatures across the southern
Appalachians. As of 3 pm, temperatures are currently in the 60s for
most locations but average highs this time of year average in the
70s. The atmosphere is very dry with PW values in the 0.4-0.5 inch
range but moisture will be on the increase later this evening into
the overnight hours. Current water vapor and RAP upper air analysis,
indicate an upper level trough to the north across the Great Lakes.
This trough is forecast to continue to track to the southeast into
the Ohio River Valley later tonight into early Monday. At the
surface, high pressure has shifted to the east with southerly to
southwesterly low-level flow across the region. A front is located
to the west in association with the upper level trough. This front
is moving into KY/TN and will continue to track eastward. Radar
imagery indicates a few returns extending along the front from the
Great Lakes southward into Kentucky. The returns along the southern
end are very light. For now, have continued with 20-40 PoPs this
evening and overnight mainly for locations north of I-40. Model
soundings indicate that saturation is rather shallow and only expect
rainfall amounts of a few hundredths of an inch. The cold front will
sweep through the region overnight bringing in a reinforcing shot of
cold air. Strong cold advection early Monday morning will drop lows
into the mid 30s to low 40s for most locations. Does not look like
frost will be a possibility due to 5-15 mph westerly to
northwesterly winds overnight. Look for sunny skies once again on
Monday as dry air sweeps in behind the departing front with the cold
airmass. PW values will drop back down into the 0.2-0.3 inch range.
Temperatures at 850 mb will range anywhere from -5 to 0 degrees
Celsius. These temperatures are near the minimum climatologically for
mid-May and would be near the 25th percentile for late January to
give a reference for just how cold and dry the atmosphere will be on
Monday. Despite the ample sunshine, highs on Monday will be well
below normal in the mid 50s for low 60s.
MA
LONG TERM (Monday night through Sunday)...
The start of the extended period will be highlighted by cold
temperatures as upper trough over the eastern states lingers one
more night and dry airmass allows for good radiational cooling
Monday night with frost possible across northeast third of the
forecast area. NAM/GFS models begins to bring in some moisture to
western and southern sections late Monday night with some cloud
cover which will keep temperatures warmer in those areas. Ecmwf
keeps drier airmass over northern sections with prevailing
northwesterly flow.
Tuesday and Tuesday night models try to bring moisture north as
southerly flow develops with light showers developing with the best
chance south Tuesday and then northern sections northeast Tuesday
night. Think the surface high will be too strong and moisture return
will be slower than models suggest Tuesday so will keep pops low.
Tuesday night went with low pops as guidance still seems overdone.
Wednesday and Wednesday night warm front to move across the region
with small rain chances to continue. Temperatures Tuesday and
Wednesday will slowly warm from upper 50s to mid 60s to mid 60s to
mid 70s but still below normal.
Thursday much warmer temperatures as large Atlantic high brings
whole area into south to southwest moist flow off the gulf of
Mexico. A system develops over the southern plains and moves slowly
northeast. The associated front makes little process east so
increasing chance for showers and thunderstorms. This activity will
be largely diurnal. Only slight chance precipitation Thursday mainly
northeast then Friday highest chances mountains and northern
plateau. Saturday and Sunday increasing rain chances for all areas.
Temperatures will warm to above normal the last 3 days with highs in
the mid to upper 80s.
TD
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
Area Forecast Discussion
National Weather Service Tulsa OK
940 PM CDT Sun May 10 2020
...UPDATE...
.DISCUSSION...
This evening some patchy drizzle/very light rain had developed
along a weak 850mb-700mb frontogenetic forcing axis positioned
northwest to southeast from North Central to East Central
Oklahoma. Meanwhile...the surface cold front had shifted south of
the Red River with northerly winds common across the CWA. North of
the mid level boundary...skies were mostly clear...while along and
south of the boundary...partly to mostly cloudy skies were
observed.
Through the late evening hours the mid level frontogenetic forcing
band is expected to continue to weaken...which can be seen by
recent radar trends...with only a slight chance of a few sprinkles
lasting into the overnight hours. Overnight tonight...a vort max
within the upper level northwesterly flow is forecast to push
into the region with additional chances for rain showers across
Northeast Oklahoma. There may be a chance that some precip makes
it into far Northwest Arkansas by 12z...if the latest runs of the
HRRR verify. For now have extended pops east to the Arkansas
border with the greater chances along the Oklahoma Kansas border
late tonight into Monday morning.
Cloud cover is also expected to increase overnight while at the
same time light surface winds become more easterly. Before the
additional clouds move in during the night...surface temps look to
fall into the 40s across much of the CWA before slightly warming
or becoming nearly steady under the cloud cover late tonight. Have
added minor adjustments to hourly temp/dewpoint/sky/wind grids
based on the mentioned above and ingested observations. The rest
of the forecast seems to be in good shape at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 46 53 47 54 / 30 60 80 80
FSM 48 59 47 55 / 10 30 50 80
MLC 47 63 52 59 / 10 20 50 80
BVO 43 49 45 55 / 40 70 90 70
FYV 39 51 45 52 / 10 50 80 80
BYV 38 49 43 50 / 10 50 90 80
MKO 46 57 47 55 / 10 40 70 80
MIO 38 49 45 54 / 20 60 90 80
F10 46 57 49 56 / 10 40 70 90
HHW 50 68 54 67 / 0 0 30 70
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...20