Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/19/17
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM...(This Evening through Friday Night)
Issued at 314 PM CST Wed Jan 18 2017
Initially in this forecast period we are dealing with mild air
aloft, with 850mb temperatures +10 to +12C which represents the peak
warmth of the inversion. This airmass will keep temperatures
relatively/seasonally mild overnight - and with
sublimation/evaporation we could see fog but am not real confident
as guidance winds are 5kt or greater.
The mild air aloft will translate into another above average
temperature day Thursday, though winds will be light and mixing
limited so our deep snow cover will again have a deleterious effect
on highs.
A plume of moisture originating to the south will lift
into the CWA late Thursday. Not certain of this source region as
the connection to the gulf ends up east of the CWA. BUFKIT
soundings also continue to show saturation will be shallow - at
just 3 to 4kft AGL, which is usually not thick enough to generate
drizzle. However both the GFS/NAM are consistent in light QPF
production late Thursday through early Saturday. Thinking is most
impacted area will be eastern slopes of the Coteau with an upslope
component - and western Minnesota where the stratus layer is
deepest. The James valley looks to experience a downslope
component as well, and will probably be dry with just stratus. Ice
accumulation should be minimal regardless due to how shallow the
saturated layer is. Advection fog is also possible as
temperatures/dewpoints increase into the 30s.
A shortwave lifting northwards will begin to saturate the profile
early Saturday. Lift provided by the shortwave to generate ice will
allow for a transition to a wintry mix - probably dominated by light
snow - with peak inversion temperatures between +1 and +2C close to
the surface. Peak omega values are only between 5 and 10 microbars
so snowfall will be light with an inch or less accumulation.
The Missouri valley will probably be dry late Thursday through early
Saturday during all this, with cooler temperatures as the core of
warmest air moves to the east, and the dominating influence on the
temperature forecast is the deeper snowpack.
.LONG TERM...(Saturday through Wednesday)
Issued at 314 PM CST Wed Jan 18 2017
The extended period starts off with a weak low pressure system over
the northern plains, with ongoing precipitation likely across
portions of the CWA. Precipitation type will be tricky as
temperatures wobble on either side of freezing Saturday into
Saturday night. Will see a brief respite in precipitation Sunday
afternoon into the day Monday, then significant differences begin to
show up in the models. The Monday night/Tuesday storm system from
previous runs is now non-existent in the ECMWF, and is stronger and
further north in the GFS. The GFS solution would bring a prolonged
period of snow to the CWA Monday night into the day Wednesday, while
the ECMWF solution keeps the region dry. For now, will not bite on
the completely dry solution and keep a slight chance to chance
mention of precipitation.
The trend of above normal temperatures will continue into the early
part of the extended period, with highs in the 30s Saturday and
Sunday. Slightly cooler air then begins to work its way in from the
northwest, with temperatures trending downward each day to highs in
the mid 20s northwest to around 30 east by Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 532 PM CST Wed Jan 18 2017
Going to break from what`s been being forecast in the TAFs over
the past couple of days. With the temperature reaching to above
freezing today at KPIR, KABR and KATY (promoting some snow melt),
fully expecting that tonight`s super-strong low level thermal
inversion will have some surface/near surface moisture trapped
within it to make fog with. The surface pressure pattern is also
shifting around to the point that light southerly winds will be
persisting at all four terminals (another variable that favors fog
around here) amid some weak pressure falls over the next 24
hours. Left KMBG in good VFR through the TAF valid period for now.
But, at KPIR/KABR/KATY did introduce some IFR visby in fog which
may or may not deepen enough to be reported as a very low IFR
ceiling. It`s possible that the winds at higher elevation KATY may
stay strong enough to support more of an IFR stratus layer
overnight, versus fog. Based off the already very impressive low
level thermal inversion showing up on tonight`s 00Z KABR RAOB, the
UPS fog technique and latest available short range guidance and
RAP model soundings fed through BUFKIT, thinking the addition of
some sub-VFR conditions overnight tonight is warranted.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...Connelly
LONG TERM...Parkin
AVIATION...Dorn
Area Forecast Discussion
National Weather Service Indianapolis IN
638 PM EST Wed Jan 18 2017
.UPDATE...
The Near Term section has been updated below.
&&
.SYNOPSIS...
Issued at 227 PM EST Wed Jan 18 2017
High pressure is expected to move through the Ohio Valley tonight.
A frontal system is expected to move through the local area around
Thursday night. Another frontal system may affect the area over the
weekend and on into early next week.
&&
.NEAR TERM /Rest of This Afternoon and Tonight/...
Issued at 638 PM EST Wed Jan 18 2017
Based on latest hourly numerical guidance and presence of low
level warm advection much of the night, have bumped min temps up a
bit.
Additionally, will carry fog mentions as some of the near term
guidance is quite pessimistic on visibilities overnight. MOS and
LAMP not nearly as bullish on fog potential, but given warm
advection and lingering low level inversion, fog certainly seems
possible. Will monitor through the evening for dense fog
potential. Previous discussion follows.
Issued at 227 PM EST Wed Jan 18 2017
Low cloud cover has held across the area so far, however some
clearing has taken place recently over southwest Illinois and
eastern Missouri. This clearing may reach the far southwest zones
late this afternoon, but more likely it will be later tonight
before significant clearing takes place as a low level inversion
holds.
Low level thicknesses tonight suggest the GFS MOS lows for tonight
look good for the most part, so little, if any, adjustments will
be made.
&&
.SHORT TERM /Thursday through Saturday/...
Issued at 227 PM EST Wed Jan 18 2017
Model data suggest upper trough currently pushing out of the
southern Rockies will eject northeast across the local area
Thursday night. Will bring in PoPs starting Thursday afternoon,
and continue them through Friday morning to cover this feature. It
appears the highest PoPs will occur Thursday night, coinciding
with the best lift. Steeper mid level lapse rates, associated with
the negatively tilted nature of the upper trough, will result in
an elevated risk for thunderstorms mainly late Thursday afternoon
and night.
Next upper disturbance ejecting out of the western trough looks to
move into the southern Plains by Saturday. Will bring chance PoPs
back into the area by Saturday as this next trough approaches.
Progged low level thicknesses generally support the GFS MOS
temperature guidance over the next couple of days. The guidance
highs on Saturday may be a little on the warm side given cloud
cover and precipitation potential. May nudge the highs down a
little in that period.
&&
.LONG TERM (Saturday night through Wednesday)...
Issued at 1257 PM EST Wed Jan 18 2017
There is high confidence the weather will be unusually warm. There
is also high confidence there will be lots of rain, but little or no
chance for snow.
The models all predict Indiana is going to be affected by air from
the Gulf Coast. Besides being warm and humid, this air should have
storm systems embedded in it.
It is too early to be precise about rain timing. POPS for any one
period may need adjusting by 20 percent. Given uncertainty about
precipitation, there is some uncertainty about temperatures.
Possible errors are about 4 degrees. It is very likely readings
will be at least 10 degrees above average most of the time.
&&
.AVIATION /Discussion for the 19/00Z TAFs/...
Issued at 611 PM EST Wed Jan 18 2017
Borderline MVFR/IFR conditions may deteriorate again overnight as
the low level inversion lingers across the area.
HRRR and Short term blends depict very poor visibilities overnight
in fog. MOS and LAMP guidance are significantly less pessimistic,
but with lingering inversion and moist low levels poor conditions
certainly seem possible. Will take most sites down to 1/2SM at least
for this package and monitor evolution of low cloud and visibilities
through the evening.
Ceilings are likely to remain poor through much of the night,
although some breakup of ceilings cannot be entirely ruled out at
the southwest sites.
Winds will be less than 10kt through the period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...JAS
NEAR TERM...JAS/NIELD
SHORT TERM...JAS
LONG TERM...JK
AVIATION...NIELD
Area Forecast Discussion
National Weather Service Jacksonville FL
900 PM EST Wed Jan 18 2017
.UPDATE...
Some high cirrus moving across the area tonight might inhibit some
radiational cooling early this evening. The SERF and HRRR are in
agreement bring an advection fog with visibilities below 1/2 mile
off the gulf and slowly across north florida and southeast
Georgia. Interestingly the fog does not seem to move into the
east coast counties until close to sunrise in both models. Will
likely see some kind of a dense fog advisory overnight likely from
west to east.
&&
.AVIATION...
fog is expected to sock in all fields overnight with visibilities
one quarter to one half mile and ceilings/vertical visibility of
200 feet or less. The fog should move into the Jacksonville Metro
area around sunrise.
&&
.MARINE...
A cold front will slide South across area waters Tonight and
stall. Weak high pressure will build back in from the South
Thursday. A frontal boundary will be just North of area waters
then through Saturday. A strong cold front will sweep East across
the region Sunday.
Rip Currents: A LOW RISK OF RIP CURRENTS IS EXPECTED ON THURSDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 57 75 59 80 / 10 10 40 40
SSI 59 72 59 74 / 0 0 20 20
JAX 57 76 58 79 / 10 0 20 10
SGJ 58 74 58 77 / 0 0 10 10
GNV 54 77 57 80 / 0 10 20 10
OCF 55 78 58 80 / 0 0 10 10
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Sandrik/Shuler/Shashy
East Central Florida Forecast Discussion
National Weather Service Melbourne FL
912 PM EST Wed Jan 18 2017
.DISCUSSION...
...Above normal temperatures through this weekend...
...Rain/storm chances increase Sunday/Sunday night...
Weakening high pressure has settled over the S FL peninsula and
Bahamas tonight. Wly gradient flow ascd with a slow moving front
over the SE coast will diminish over night with calm to very
lightwinds remaining. upr clouds are quite thin and shouldnt
significantly affect temperature forecast. Fog potential remains
challenging. It is expected there will be development especially
across Nrn section and the interior away from the immediate coast.
HRRR visibility product continues to pushing a large area of low
visibility (lessthan a half mile) into areas along/west of I-4 from
the west. The current forecast has areas of fog mentioned there, so
not planning any significant changes.
Otherwise, overnight lows look similar to those of late, upper 50s
over the mainland and lower 60s on the barrier islands.
&&
.AVIATION...
Conditions will be VFR through at least 19/06z. Will have to watch
for low visibility afterward at the terminals along/west of I-4 as
suggested by the HRRR model.
&&
.MARINE...
Tonight-Thursday...Continued good boating conditions as a high
pressure ridge centered over the southern waters keeps the gradient
weak. Winds generally west/northwest tonight, then north becoming
onshore Thu afternoon. Speeds will be 10 knots or less. Seas 1-2
feet nearshore and 2-3 feet offshore.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
JP/MB
Area Forecast Discussion
National Weather Service Marquette MI
627 PM EST Wed Jan 18 2017
.SHORT TERM...(This evening through Thursday)
Issued at 312 PM EST WED JAN 18 2017
12Z raobs/latest wv imagery and RAP analysis show a split flow with
polar branch upr rdg over central Canada into the nrn Plains to the
n of a closed lo in the subtropical jet over the srn Rockies into
the srn Plains. Unseasonably warm Pacific air has flooded into srn
Canada and the nrn CONUS to the s of the polar branch jet stream.
12Z h85 temps were as hi as 6C over scentral Canada at The Pas
Manitoba and YPL to aoa 10C over the nrn Plains, including 13C at
Glasgow MT. The 12Z INL/MPX/GRB raobs also show a very dry mid lvl
airmass under the upr rdging, so skies are generally mosunny, which
has allowed temps to rise aoa 40 at some places. There is a shrtwv
sliding esewd thru NW Ontario, but with the mid lvl dry air in
place, only some hi clds are brushing nrn Lk Sup. The exception is
over the ern cwa, where a ssw flow off Lk MI is resulting in a good
deal of lo clds/some fog that has restricted the diurnal temp rise.
Main fcst concerns in the short term are fog/lo cld trends as bldg
upr rdg/mid lvl dry air dominate the wx pattern.
Tngt...As the Ontario shrtwv moves quickly to the e and the pres
gradient weakens under slowly rising upr hgts/lingering mid lvl dry
air and sfc rdg axis, expect fog/lo clds to dvlp over the melting sn
pack. While a wshft more to the w behind passing shrtwv to the n wl
cause the lo clds near Lk MI to at least briefly break up into this
evng, a backing llvl flow to the sw later tngt suggests the lo clds
and fog wl be more focused in this area again. With the lighter
winds and dry mid lvl air, lo temps at the colder interior central
locations wl dip into the teens.
Thu...Morning fog/lo clds wl grdly dissipate but be most persistent
again near Lk MI, especially to the e of Escanaba with a llvl sw
flow off the water. Many of the models do show the sw flow wl tap
more llvl mstr and some lo clds now present to the sw over se MN/sw
WI and advect these into the Upr Lks. But with at least partial
sunshine and the unseasonably warm airmass lingering, expect hi
temps to rise aoa 40 again away fm Lk MI. If the hi temp at the
Marquette NWS reaches at least 40 again, Thu wl be the 4th day in a
row when the mercury has at least reached that mark at this office.
This streak will tie the record consecutive days with a max of 40 or
better that was established fm 1/11 thru 1/14 in 1987 at the
Marquette NWS.
.LONG TERM...(Thursday night through Wednesday)
Issued at 311 PM EST WED JAN 18 2017
January thaw with well above normal temperatures continues into
early next week. Mid to late next week upper level troughing is
expected to settle from western Canada into central portion of the
Conus which should bring colder pattern back to Upper Great Lakes.
As the pattern begins to shift back to colder conditions there is
potential for a storm system to affect the Great Lakes. Would be
cold enough to see some system snow late Tue into Wed.
Main issue later this week will be increasing low-level moisture blo
1km/3kft/900mb as high pressure ridge over Ohio Valley moves east
and positive tilted upper level trough and associated sfc trough
lifts across the Upper Great Lakes. Deeper moisture and stronger h7-
h5 q-vector convergence/lift arrives late Thu night into Fri
morning. ESE winds later Thu aftn into Thu night and the low-level
moisture could support light drizzle for upslope areas of central
Upper Michigan. Temps either side of 32F will be on the edge for
drizzle/freezing drizzle. As deeper moisture and stronger lift
arrives could see freezing rain late Thu night into Fri morning,
especially in the scntrl cwa where the most qpf occurs when temps
are forecast to be blo freezing. Will continue to mention the icing
potential in the Hazardous Weather Outlook (HWO).
Shortwave and stronger forcing continues lifting north on Fri and
there may be a lull in rain (or at the least steadier rain may
diminish to drizzle for a time) later Fri into Fri night. Another
shortwave and area of forcing lifts across Upper Great Lakes on Sat
so expect another period of steadier light rain to affect Upper
Michigan. Most of the deeper moisture is blo h7/8-10kft so qpf
should stay well blo 0.25 inch. However, even light rain will lead
to saturated low-levels and increase drizzle potential over cntrl
cwa and across the Keweenaw. Melting snowpack, ongoing drizzle and
sfc dwpnts rising above freezing will also lead to fog potential.
Unlike the warm conditions ongoing, it appears that conditions this
weekend will be more murky featuring more in way of rain/clouds and
fog.
Sun into Mon strongest shortwave energy over the central Conus will
be tracking from southern Plains to the Tennessee River Valley.
Expect fairly strong sfc low Tennessee River Valley into the Ohio
Valley while a weak trough extends northwest across the western
Great Lakes region. Majority of heavier qpf should be tied into the
system to the southeast of here, but weaker shortwave energy lifting
across the Great Lakes may bring some light rain to parts of Upper
Great Lakes on Mon. Best chances would be eastern cwa closer to
stronger jet forcing. As alluded to earlier, deep troughing is
forecast to develop across western half of the Conus Tue into Wed
which results in strong lee side low pressure forming over the
middle Conus on Tue and lifting toward Great Lakes late Tue into
Wed. Gulf moisture will be available for this system with mixing
ratios over 3g/kg shown by ECMWF. Seems likely there could be
stronger system affecting middle Conus into the Great Lakes, though
energy may remain tied into stronger storm system affecting east
coast early in the week. Both of these solutions are feasible. If
there is a stronger storm system in the middle Conus, one of the
main issues would be how far west the wrapped up low would track and
ultimately what will be extent of warm air/mixed precip with the
system. Plenty of time to sort out those details.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 627 PM EST WED JAN 18 2017
With some low level dry air in place over the nw half of Upr MI,
expect
vfr conditions to prevail into at least this evng. Not out of the
question there could be some mvfr cigs at CMX this evng with a
strengthening upslope w wind component and them some lo clds/fog at
SAW overngt with a period of lighter winds under passing sfc hi
pres, but maintained previous vfr fcst as confidence is lo on these
outcomes. The strengthening wsw wind above nocturnal invrn wl result
in some llws at IWD late tngt into Wed mrng.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 246 PM EST WED JAN 18 2017
A relatively weak pres gradient over the Upper Great Lakes in the
absence of any strong weather systems will result in winds under 20
kts over Lake Superior most of the time into early next week.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...07
MARINE...KC
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1012 PM EST Wed Jan 18 2017
.DISCUSSION...
No major adjustments are needed to the forecast this evening.
Ridging from 850 to 300 mb will be moving east of the Appalachians
tonight, with a SW flow of positive theta-e advection and
isentropic lift developing late tonight. As reflected in the going
forecast, rain showers over MS are moving NE and are projected to
reach our area between 09-12Z. The HRRR and RAP appear to have a
good handle on this precip. Current obs match up pretty well with
the forecast, and only a few slight tweaks to temperature and sky
grids will be made.
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&
$$
DGS
Area Forecast Discussion
National Weather Service Nashville TN
920 PM CST Wed Jan 18 2017
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...Area of precipitation associated with an inverted
trough situated to our west remains far upstream, and the HRRR
doesn`t bring the bulk of this activity into Middle Tennessee
until after 06Z. Have therefore made some adjustments to POP`s,
mainly reducing the categorical area in southwest Middle Tennessee
to likely. Have also removed mention of thunderstorms prior to
12Z given the current lack of instability and the dearth of
instability showing up on the forecast soundings the remainder of
the night. Otherwise, the hourly grids are holding up reasonably
well, and no other changes to the forecast are currently planned.
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR flight conditions at TAF time, but this will be changing after
06Z tonight as our next weather system begins to move into the
region. Cigs/vis will begin to fall into MVFR, then IFR by late
morning Thursday as the atmosphere saturates. Once these IFR
conditions settle in, they will likely persist through Friday
morning. TS will likely be introduced with the next TAF issuance
for Thursday evening.
Winds will be relatively light, starting easterly, then shifting
southeasterly by Thursday morning as the warm front passes through
Middle TN.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......08
AVIATION........Unger
Area Forecast Discussion
National Weather Service Norman OK
552 PM CST Wed Jan 18 2017
.DISCUSSION...
00Z TAFs.
&&
.AVIATION...
MVFR and locally IFR ceilings across the southwest will become
more widespread overnight with areas of fog developing.
visibilities will also likely get down to 1 mile or below in some
areas with fog and perhaps drizzle. HRRR and RAP indicate the
dense fog may become fairly widespread even later this evening,
so will watch trends through the evening.
&&
.PREV DISCUSSION... /issued 259 PM CST Wed Jan 18 2017/
DISCUSSION...
Widespread low-level moisture is likely to result in another
cloudy/foggy, perhaps drizzly, early morning on Thursday. As a
storm system over the southern Plains begins to move east by
midday tomorrow, some clearing is expected from southwest to
northeast.
A dry and warmer day is expected Friday, before another storm
system arrives for the weekend. Instability will be quite weak,
but a few thunderstorms will be a possibility, mainly over the
southeast half of our forecast area, Saturday night.
Breezy and dry conditions Friday, Sunday, and Tuesday will
elevate the risk of wildfires on those days.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 43 63 38 66 / 0 0 0 0
Hobart OK 41 64 36 66 / 0 0 0 0
Wichita Falls TX 42 68 41 70 / 0 0 0 0
Gage OK 38 60 33 63 / 0 0 0 0
Ponca City OK 43 60 37 62 / 10 10 0 0
Durant OK 45 66 45 69 / 20 10 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Paducah KY
513 PM CST Wed Jan 18 2017
.UPDATE...
Issued at 512 PM CST Wed Jan 18 2017
Updated Aviation discussion for 00Z TAF Issuance.
&&
.SHORT TERM...(Tonight through Friday night)
Issued at 249 PM CST Wed Jan 18 2017
The main concern in the short term portion of the forecast is a
storm system pivoting north northeast out of the southern Plains
Thursday and through the mid-Mississippi Valley Thursday night.
Ahead of it, winds will become easterly and lots of elevated
moisture will return to the region beginning late tonight. The
overall trend in the 12Z guidance is for a slower arrival time for
the elevated showers. The HRRR has been consistent in killing off
any light shower activity moving northeast out or Arkansas this
evening.
Generally followed the 12Z GFS and ECMWF for the placement of PoPs
for Thursday and Thursday night. The models are indicating a
pretty sharp western edge to the heavier rains, so western and
northwestern portions of the region may see a quick hit of some
showers late tonight and Thursday morning, and then dry out fairly
quickly.
The 12Z guidance is in decent agreement in developing some meager
elevated instability, so will keep a slight chance of thunder
going Thursday into Thursday evening. Do not feel that enhanced
rainfall rates will persist long enough at any one place to cause
much in the way of flash flooding. However, given the saturated
soil conditions across the region, and in particular, west
Kentucky, did give serious consideration to a Flood Watch for
Thursday.
6 hour FFG values over west Kentucky are well over 2 inches, so
the 1.25"-1.6" currently forecast over a 12 hour period in west
Kentucky should not cause major problems. The FFG may be a bit
optimistic, so will give the areal flood concerns a decent write
up in the HWO. The bulk of the rains should hold off until the
midnight shift forecast is complete, so there is still time for a
Watch or at least an SPS. Needless to say the forecast rainfall
will only aggravate river flooding across the region.
As this upper system lifts north and weakens, another storm system
will emerge into the central Plains Thursday night and Friday. It
will actually lift a warm front north through our area late
Thursday night and Friday. There could be some shallow instability
that could be just deep enough to support a few showers near the
front on Friday, so will have 20% PoPs over at least the
west/northwest half of the area through the day. Friday night
will actually be dry. Yeah!
For tonight, the low clouds have cleared over much of southern
Illinois, but thicker high clouds will keep things more cloudy
this evening than clear. The low clouds should lift back to the
north quickly by midnight, and despite easterly winds, a non-
diurnal temperature trend is a good bet. Much of the area will
likely see lows at some point this evening, with steady or
slightly warming temperatures after midnight.
It will be mild through the period, with the warmest conditions
expected behind the warm front on Friday. Much of the area should
climb above 60 Friday.
.LONG TERM...(Saturday through Wednesday)
Issued at 249 PM CST Wed Jan 18 2017
Main story in the long term period is the unseasonably warm
temperatures and a storm system that will impact our area over the
weekend.
The region will reside in southwest flow aloft on Saturday, with
warm, moist air being transported into the area. Weak forcing ahead
of energy moving into the Southern Plains on Saturday should result
in at least isolated to scattered showers through the day, although
many places may end up dry for most of the day. The main piece of
energy will move toward the area Saturday night through the 1st part
of Monday, with precip chances increasing during this time. The peak
time period for best areal coverage appears to be Sunday into Sunday
night. From Saturday afternoon thru Sunday, models are hinting at
enough instability for thunder potential. With sufficient MUCAPE,
marginally negative showalters, and LI`s from 0 to -3, went ahead
and included slight chance of thunder. QPF from the weekend system
is expected to be highest over western KY (roughly 1-1.50"), to
around 0.50" across western and northwest counties.
The system is expected to pivot out of our area sometime on Monday,
although exact ending time is somewhat in question. Drier weather is
then expected Monday night into the day on Tuesday as upper level
ridging moves in. Discarded the 12Z ECMWF for now, as it came in wet
for Monday night/Tuesday morning for the 1st time and only model
showing it. Troughing over the western states will work east by
midweek, bringing a cold front into the area. Currently the best
forcing looks to be well north of our area, closer to the sfc low
track, and models aren`t in great consensus on the amount of
moisture moving through our area. So for now only pops late in the
period are slight chance for Tuesday night.
As for temperatures, Saturday will be the warmest day with highs in
the 60s areawide. Would not be surprised to see a few locations
touch 70, especially if any breaks for sunshine occur. Record highs
may be challenged (Paducah: 70, Evansville: 71, Cape Girardeau: 68).
Temperatures will slowly migrate down heading into next week with
50s common Monday thru Wednesday, still some 10 degrees above
normal. There has been good consensus with long range guidance
hinting at a cooler pattern setting up later next week and possibly
lasting thru the end of the month, as troughing sets up over the
eastern half of the country.
&&
.AVIATION...
Issued at 512 PM CST Wed Jan 18 2017
Open Gulf stream/fetch readily depicted by both Satellite/Radar
will lead to lowering CIGS and VSBYS tonight-tmrw, with IFR
conditions at times. Some improvement noted late in the planning
period for KCGI/KPAH as conditions worsen eastward (KOWB) same
time, given the west to east translation of the overall system.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
Area Forecast Discussion
National Weather Service Shreveport LA
531 PM CST Wed Jan 18 2017
.AVIATION...
Convection has moved east of our NE TX terminal locations early
this evening with a few more hours of prevailing showers at the
ELD/MLU terminal before we begin to see brief break from the
widespread shower activity. In the wake of the convection across
NE TX...will need to watch for the development of dense fog as
several locations west of a LFK...GGG...TXK line have gone down to
1/2SM with patchy drizzle as well. Unsure just how far east this
fog and/or drizzle will make it into our remaining terminals
overnight but did at least make account of it at the LFK/GGG/TYR
and TXK terminals. HRRR and latest NAM output suggest
redevelopment overnight from SE TX into SW LA moving quickly north
and east. This would help to mix out any dense fog and or drizzle
that might make it into SW AR and NW LA but those terminal
locations would be back in a prevailing -shra type pattern with
IFR/LIFR ceilings.
Kept prevailing -shra and IFR/LIFR ceilings going through much of
the day on Thu across our eastern terminal locations before precip
moves out by late afternoon. Should see VFR conditions returning
to our NE TX terminals by mid to late afternoon as well.
13
&&
.PREV DISCUSSION... /issued 322 PM CST Wed Jan 18 2017/
DISCUSSION...
Back edge of current radar activity has shifted just south and
east of I-30, and still consisting of bkn areas of rain, with very
isold embedded tstms to the south. However, one more short wave
will interact with still saturated airmass to regenerate showers
and possible tstms overnight. Mid lvl drying early tomorrow
warranting a reduction of pops for Thursday. In the wake of these
showers, expect fog to develop, especially near the Red River
valley where lgt winds and soggy ground interact with clearing
skies, and warm air advection above sfc inducing a capping
inversion. Overnight temps to remain fairly steady and may even
rise slowly. Deep sw flow to continue thru wknd with mid lvl
moisture making a return on Friday, yielding only partly sunny
skies, with showers returning from the south Friday night and
temps warming to around 70 degrees or so durg the day. Instability
appears sufficient for a few stg storms Sat into Sat night,
despite limited low lvl shear. Once the upper trough inducing this
stgr convection begins to move east by Sunday, stg northerly flow
in mid lvls near 100 kts will finally pull in much drier airmass,
and rainfall will be lacking in extended period.
/VII/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 54 71 56 75 / 80 40 10 10
MLU 54 70 56 75 / 80 60 10 10
DEQ 48 65 48 68 / 50 20 10 10
TXK 49 65 54 71 / 60 20 10 10
ELD 49 66 53 73 / 80 50 10 10
TYR 50 71 54 74 / 50 20 0 10
GGG 52 71 55 74 / 60 20 10 10
LFK 55 73 56 76 / 70 30 10 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
VII/13