Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/26/17
Area Forecast Discussion
National Weather Service Bismarck ND
934 PM CDT Sat Mar 25 2017
.UPDATE...
Issued at 926 PM CDT Sat Mar 25 2017
Have backed off a bit more on the timing of potential rain over
the southwest/south central in line with latest guidance. Have
also trimmed down precipitation chances over northern locations.
Updates have been sent.
UPDATE Issued at 626 PM CDT Sat Mar 25 2017
Have backed off on timing of precipitation chances over the
southwest as rain appears to remain well off to the west and
latest high-res models have slowed things down a bit. Otherwise,
previous forecast looks good.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 304 PM CDT Sat Mar 25 2017
At the upper levels, a west coast trough will keep the state in
southwest flow through the short term. While the two most vigorous
waves will pass to the north and south, there does appear to be
enough convergence at the surface for some light precipitation along
an inverted surface trough that will extend from western South
Dakota into southwestern North Dakota overnight. Many of the High
Resolution models are showing fog from east of the Missouri River
valley to the James River valley. While, the HRRR specifically
looks a bit overdone, the feeling is that at least patchy fog will
be possible over these areas overnight and Sunday morning.
Light precipitation chances will continue to propagate east
through the day on Sunday bringing more chances of light showers
to much of the forecast area. Over the James River valley,
forecast soundings show a very brief opportunity of a light
mixture of rain, freezing rain, and possibly sleet Sunday morning.
.LONG TERM...(Sunday night through Saturday)
Issued at 304 PM CDT Sat Mar 25 2017
Progressive flow aloft will keep the area in an active pattern,
but split flow will keep any major chances of precipitation to a
minimum. For now, the best chances for some light precipitation
appear to be overnight Tuesday and into Wednesday morning. From
there, model agreement tends to diverge with regards to wave
strength and timing specifics. For this reason, elected to keep
with our in house blend of global models throughout the long term.
Above average high temperatures, generally in the 50s and 60s,
will stick around through the extended period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 626 PM CDT Sat Mar 25 2017
Patchy fog will develop later tonight over central North Dakota
into the James River Valley bringing localized IFR conditions.
The fog will deteriorate Sunday morning. Some light rain is
possible over southern areas overnight into early Sunday morning.
Localized MVFR visibility will be possible. Otherwise...VFR
conditions will prevail.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJS
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...JJS
Area Forecast Discussion
National Weather Service Cheyenne WY
338 PM MDT Sat Mar 25 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 300 PM MDT Sat Mar 25 2017
Unsettled weather ahead through the next few days into next week.
Forecast challenges deal with timing and location of precip.
Currently...Cold front extends from eastern Montana, south to near
Casper to just west of Rawlins, into northern Utah this afternoon.
Showers confined to northwestern Wyoming on mosaic radar this
afternoon. Pretty tranquil conditions over our county warning area
this afternoon as skies continue to thicken and lower. afternoon
temperatures running in the mid to upper 50s across the area.
Front forecast to move into our western zones (Carbon County)
after 00Z (5PM) today to Converse and Albany Counties near 06Z
(11PM)and then into the northern Nebraska Panhandle and around
Cheyenne by the 09-12Z (2-5AM) timeframe. Would expect these time
to be when showers would begin to break out across the CWFA. HRRR
simulated radar confirms this timing as the front moves through
tonight. Not a lot of cold air behind this system. 700mb
temperatures fall from +1 to +4C this afternoon down to -4C to -1C
from west to east. Snow could develop in the valleys out west as
this colder air moves into the area. As for eastern areas, do
expect showers to remain all liquid.
Not expecting much in the way of accumulations as QPF fields are
fairly low on all the guidance forecasts. Looks like a
cloudy/showery day for Sunday with highs in the 40s and low 50s
from west to east.
Best chances for precip looks to be late in the short term as our
next Pacific low moves into northern New Mexico Tuesday
afternoon. Given the performance of the guidance on our last low
pressure system, will lean towards a low confidence forecast on
snow accumulations and timing for now.
.LONG TERM...(Tuesday night through Saturday)
Issued at 300 PM MDT Sat Mar 25 2017
Tuesday night/Wednesday...Strong upper trough moves slowly across
northern New Mexico with widespread rain and snow showers progged to
spread west to east across our counties Tuesday night. After
daybreak Wednesday, the upper low is forecast to track into east
central New Mexico with ridging moving over our counties north of
the low. In response, precipitation is expected to end from west to
east during the day.
Thursday...Transitory shortwave ridging aloft progged to move across
our counties, producing a dry day with warmer temperatures due to
more sunshine and a moderating airmass.
Friday...Next vigorous closed low aloft progged to move southeast to
near the Four Corners by late afternoon, while a cold front moves
across our counties, with a chance of showers across most of our
region. Cooler temperatures due to expected precipitation and
extensive cloud cover.
Saturday...The closed low is progged to continue moving southeast
into southern New Mexico, a further south track than the previous
weather disturbance, thus lesser chances for precipitation across
our counties, especially in the afternoon when the bulk of
precipitation and clouds associated with the upper low, is progged
to move over Colorado.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 335 PM MDT Sat Mar 25 2017
Wyoming TAFS...VFR, except for MVFR at Cheyenne from 09Z to 15Z,
MVFR at Laramie from 06Z to 15Z, and MVFR at Rawlins from 03Z to
15Z.
Nebraska TAFS...VFR, except for IFR or MVFR from 11Z to 18Z.
&&
.FIRE WEATHER...
Issued at 300 PM MDT Sat Mar 25 2017
Unsettled weather for the upcoming work week. No fire weather
concerns through the weekend. Minimum humidity values will mostly
be above 25 percent this afternoon. Cooler temperatures along
with a chance of rain and snow showers are expected on Sunday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Duluth MN
926 PM CDT Sat Mar 25 2017
.UPDATE...
Issued at 926 PM CDT Sat Mar 25 2017
Clouds continue to expand north and west this evening with light
precipitation moving through parts of northern Wisconsin. KPBH
reported light rain for a brief period and area radars show weak
echoes continue to move north. We don`t plan any big changes to
the forecast at this time. There is some concern portions of
Ashland and maybe even Bayfield Counties could get enough freezing
rain to warrant an advisory. Temperatures were from 31 to 36
degrees across those counties and there may be a bit more of a
drop but clouds continue to thicken. We will not add any more
counties to the advisory at this time but continue to monitor
radar/model/observations.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 314 PM CDT Sat Mar 25 2017
Cloud cover is expected to increase again overnight tonight ahead of
a stacked area of low pressure that will be situated over the mid
Mississippi River Valley overnight. A lobe of PVA will eject from
this low pressure system, along with increasing 850-700 mb layer
warm air and moisture advection, will support increasing chances
of precipitation over northwest Wisconsin this evening, and then
from the Brainerd Lakes northeast towards the Minnesota Arrowhead
Sunday morning. East to northeast on-shore winds off of Lake
Superior will continue through the day Sunday, which should advect
some cooler temperatures over land. This may lead to the
development of some patchy fog along the North Shore. Confidence
is not high that any dense fog will develop despite what a few of
the models were progging, including the RAP and HRRR models, and
to a lesser extent - the WRF ARW/NMM models. Cloud cover and
stronger winds due to the favorable fetch should help limit the
fog, but dew point depressions still look favorable. Due to the
cooler temperatures being advected on-shore, still think some
patchy fog is likely, but don`t think it will be dense. Therefore,
introduced patchy fog over the North Shore overnight.
The main concern for the overnight hours will be the precipitation
types overnight. As the PVA and warm air advection arrives, the
thermal profiles are expected to cool. Deepening moisture profiles,
as indicated in the RAP/NAM model soundings, along with cooling sfc
temperatures, will lead to mainly freezing rain across portions of
northwest Wisconsin, with the possibility of snow/sleet mixing in.
The most uncertainty for this forecast comes from the exact
temperature profile as the sfc temperatures will be right at
freezing. Any change in the sfc temperatures, either plus or minus
a degree, will have big changes in p-types. The guidance is
hinting at favorable sfc temperatures for freezing rain along the
higher elevations of the Gogebic Range in Iron county. Due to the
potential for a wintry mix, with freezing rain being the primary
p-type expected, decided to issue a Winter Weather Advisory for
Iron county tonight and into mid Sunday morning until temperatures
warm up. Smaller changes of freezing rain are possible along the
North Shore overnight as well, but the heaviest QPF is expected
over northwest Wisconsin, so not expecting as much ice
accumulation along the North Shore. Ice accumulation in Iron
county could be up to a tenth of an inch, with the greatest
amounts expected in the higher elevations of the Gogebic Range.
Precipitation will transition to all rain late Sunday morning
through the afternoon as the temperatures increase. Temperatures
will remain near or above seasonal averages during the day Sunday,
with decreasing chances of precipitation Sunday afternoon and
evening.
.LONG TERM...(Sunday night through Saturday)
Issued at 314 PM CDT Sat Mar 25 2017
No major storms appear in the offing for the upcoming week, but
there will be periodic chances for light precipitation, both at the
beginning of the period, and again later in the week.
At the beginning of the extended periods Sunday night and Monday,
ongoing light precipitation will be winding down and ending as the
slow-moving upper low over the middle Great Lakes region slowly
pulls away to the east.
As the eastern North American trof axis amplifies a bit early to mid
week, high pressure will strengthen slightly over Canada, and should
be sufficiently strong to push a weak surge of slightly colder air
southward into the western Lakes region Tues-Wed. This should also
be sufficient to minimize precip chances during this time with
general large-scale subsidence.
Beyond Wednesday, the medium range models have significant
differences in both amplitude and timing of various weak
disturbances that will affect the Northland through the remainder of
the 7 day forecast window, which is also supported by the rather
large spread in the ensemble solution space. The region should
transition to a slightly warmer airmass with time, but there will
also likely be periodic chances for light precip during the Thursday-
Saturday time range, and it seems likely that there will be at least
a couple of short time windows where light wintry mixed precip will
be possible across the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 657 PM CDT Sat Mar 25 2017
Low pressure was located in central Missouri as of 23Z and moisture
was surging northward. The low will move into the MO/IA/IL border
by 12Z Sunday and a lobe of vorticity will move north into the
Northland overnight. MVFR/IFR ceilings will expand to all areas
overnight. Light rain or light freezing rain will also develop
from southeast to northwest through the night, most widespread
over northwest Wisconsin. There is still uncertainty whether or
not KHYR will experience freezing rain later tonight. Temperatures
did warm nicely this afternoon into the middle forties and clouds
have moved back in which will cause temperatures to fall more
slowly tonight. We kept a period of freezing rain from 09Z to 13Z
in the latest TAF and will reevaluate with the next issuance.
Rain or freezing rain may reach into portions of northeast
Minnesota later tonight but confidence is lower there so we only
have a mention at KDLH for now. Fog may also develop tonight and
we did lower the visibility in some of the TAFS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 30 38 30 46 / 40 40 10 10
INL 29 47 28 48 / 0 0 0 10
BRD 32 45 32 54 / 30 20 10 10
HYR 33 42 31 48 / 60 50 30 10
ASX 32 39 30 45 / 60 50 30 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 9 AM CDT Sunday for WIZ004.
MN...None.
LS...Small Craft Advisory until 4 AM CDT Sunday for LSZ121-140>148.
&&
$$
UPDATE...Melde
SHORT TERM...JTS
LONG TERM...Miller
AVIATION...Melde
Area Forecast Discussion
National Weather Service Des Moines IA
651 PM CDT Sat Mar 25 2017
.SHORT TERM.../Tonight through Sunday/
Issued at 347 PM CDT Sat Mar 25 2017
The primary concern through the period will be precip trends. The
parent upper low and its attendant short waves/PV anomalies
continues to slowly advance through MO this afternoon and should
only reach the IL/WI border by 18z Sunday. Our current deformation
zone precip band should continue to slowly deteriorate into Sunday
morning but not go away completely with precip just becoming more
spotty as forcing becomes neutral to subsident as sufficiently deep
moisture is less and less prevalent. Soundings suggest our moisture
depth should stay in the 1-3km depth so patchy light rain or drizzle
should be more common than steadier rain with persistent stratus in
the broad cyclonic flow. The only exception to this may be SE this
evening were weak convection is possible near the core of the upper
low. Have mentioned some fog potential too as the latest ESRL HRRR,
HRRR and RAP runs are all quite bullish. Do not expect anything
dense however due to the steady blanket of stratus.
The precip will likely end by Sunday afternoon however as the
moisture layer shrinks due to mixing from below and drier air above.
Temperatures should fall no more than several degrees tonight with
little rebound Sunday either, especially north. SE sections may mix
sufficiently to get well into the 50s however.
.LONG TERM.../Sunday night through Saturday/
Issued at 347 PM CDT Sat Mar 25 2017
Monday...
20z Sat water vapor imagery clearly picking up on an upper low
spinning near the four corners region of the SW CONUS. Now
approaching 48 hours out, models have finally begun to come into
agreement with one another...more or less beginning to cluster
around the ECMWF (southern) track for the track of this low and
the sfc reflection. Sfc low now slated to track through southern
Missouri towards Kentucky. Subsequently, best forcing looks to be
in Missouri, with a narrow ribbon of frontogenetical forcing near
900mb to 800mb barely clipping the 2 southernmost tier of counties
in the DMX CWA. KOTM Bufkit soundings show pocket of dry air
around 800mb to 650mb that will make notable precip growth
difficult. Thus have kept QPF less than 0.05 inches, which even be
too high yet.
Tuesday and Wednesday...
Sfc high pressure looks to fill in behind the Monday system.
Models in good agreement with placing the high near the
Minnesota/Canada border by 12z Tue, and by Lake Superior by 00z
Wed. Aloft, zonal flow should remain in place, accompanied by a
jet streak across Minnesota to Michigan, which should keep us
under upper to mid-level cloud cover. Though strength of
insolation not superb this time of year, depending on thickness of
clouds, temps may need to be knocked down a few degrees.
Thursday and beyond...
Models continue wild variation with tracking of the next system.
Most long-range models and ensembles now pick up on upper level
low swinging through the TX/OK panhandle around 00z Thu. Tracing
this low back to its source region, the low is picked up on water
vapor imagery, and it should come onshore around 12z Monday. So,
tonight`s 00z runs may not vary much...but hopefully the 12z Sun
and 00z Mon runs should begin to have better resolution with the
track of this system. 12z Sat long-range solutions holding
firm/stubborn with their 12z Fri solutions. 12z Sat GEM has
joined the ECMWF with the northern solution. In short, the 12z GFS
places the sfc low over the southeastern CONUS at 12z Fri, the
12z Sat ECMWF places the sfc low over central Illinois, and the
12z Sat GEM actually places the low over southern Iowa. Regardless
of location, warm sector side of low should be able to tap into
gulf moisture...and support may be there for strong/severe storms.
&&
.AVIATION.../For the 00Z TAFS through 00Z Sunday evening/
Issued at 650 PM CDT Sat Mar 25 2017
Main concerns are cigs/fog and potential for light rain or
drizzle. Old low continues to spin up showers or light drizzle
over the area. Winds are expected to diminish slowly in the next
24 hours. Cigs remain IFR and likely to drop to LIFR at times
again overnight. Fog is also beginning to develop over the
southeast. Hires models suggest that fog will fill in over much
of the south overnight. Confidence not high enough to lower visby
to IFR yet over all of the south. May need to update with time if
areal coverage expands. Conditions slow to improve Sunday but some
improvement expected toward end of period. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Small
LONG TERM...Kotenberg
AVIATION...REV
Area Forecast Discussion...Correction
National Weather Service Fort Worth TX
1036 PM CDT Sat Mar 25 2017
.UPDATE...
Main update was to include a mention of patchy fog for southern
zones as well as adjust temperature and dewpoint trends during
the overnight hours. Also, made a few slight changes to PoPs based
on the latest arriving model output.
Surface analysis this evening revealed that low level moisture
was beginning to lift northward along the Upper TX Coast with the
00 UTC RAOBs indicating the 1" PWAT isopleth was slowly lifting
northward. Closer examination of these RAOBs indicate that the
moisture depth is about 1km or so suggesting that perhaps a
slightly richer quality of moisture does exist. The 4-Corner`s
upper trough will continue to pivot eastward and with subsequent
lee-side pressure falls ongoing and forecast to continue, this
plume of low level moisture should have little in the way to
impede its progress through the overnight hours. With the
increasing low level moisture, there`s a potential for some light
and patchy fog mainly across Central zones. Farther north,
northerly winds, due to the influence of the weak front/surface
low across the Missouri Valley, will eventually become more
easterly and southeasterly, but not before temperatures fall into
the low 50s. If southeasterly winds do not occur before sunrise,
it`s possible that temperatures along the Red River are not low
enough. This front will have ramifications for PoPs on Monday
morning and this is discussed below.
With regards to Sunday`s severe weather potential, the threat
still remains contingent on several factors. The first will be the
degree of low level mixing that occurs as low level moisture lifts
northward. RAP output indicates that low to mid 60 degree
dewpoints will be possible along the Red River. This is somewhat
interesting as the RAP typically mixes quite deeply and one would
not expect such high dewpoints as far north as the Red River.
Other model guidance, however, remains tightly clustered around a
solution that places the 60 degree isodrosotherm a little farther
south with mainly 50s along the Red River and I`ve trended
dewpoints closer to this solution. This is important as even a
minor change in surface dewpoints can result in the amount of
instability and low level buoyancy to perhaps breach the cap. If
the RAP is correct, there could be a bit more instability in place
and a slightly weaker cap than is advertised at this time.
With regards to the cap---a majority of hi-resolution and coarser
guidance do weaken the cap sufficiently in the 21-00 UTC time
frame near the Highway 281 corridor. With sufficient convergence
along the dryline, we should see a few storms develop.
Environmental parameters do support a supercell storm mode. With
an unseasonably warm and well mixed boundary layer, LCLs will
likely remain high which would foster more of a damaging wind and
large hail potential. If the quality of moisture is a bit better
and can resist being scoured out completely, LCLs would in theory
be lower. This combined with an environment characterized by
favorable turning of the low level winds (large hodographs) does
mean that a slightly greater tornado threat would materialize
should the low level moisture quality be a bit higher than
currently thought. This is something that we will closely monitor
with additional model output and a new suite of upper air data
Sunday morning. With that said, I nudged PoPs upward by a hair and
extended them a bit farther south and west along the axis of
greatest instability and weakest inhibition for Sunday afternoon.
As has been stressed the past few days, the probability for
numerous severe storms is low (likely just a handful at best), but
should storms get going, they will more than likely become severe.
The most likely area for strong ot severe storms will be generally
along and north of I-20.
The only other change in the forecast was to add a low chance for
showers and storms Monday morning across eastern/southeastern
zones. As the upper forcing slides eastward, it appears that a
cold front will overtake the dryline. Various NAM solutions continue
to produce QPF. With the forcing and expected low level moisture
in place, I went ahead and added a sliver of 20 PoPs out across
eastern zones. The remainder of the forecast looks to be in good
shape.
24-Bain
&&
.AVIATION...
/ISSUED 620 PM CDT Sat Mar 25 2017/
Winds will become light and variable toward sunset and then
southerly later during the evening as a surface high moves off to
the east. Low clouds and areas of fog are expected to develop
across South Texas overnight tonight and some low clouds may
spread north into the Waco area by 12z and into the Metroplex TAF
sites after daybreak. Thus have indicated a TEMPO BKN015 at KACT
from 12 to 16z and a TEMPO BKN020 at the Metroplex TAF sites for
the 13 to 16z period.
Southerly winds will be on the increase Sunday as a lee side
trough deepens. Expect south winds 10-12 knots at 13z to increase
to 15-17 knots by 16z with some gusts of 25 knots possible through
the afternoon. Although a capping inversion will be in place,
isolated to scattered thunderstorms may form along the dryline by
mid afternoon along and north of the I-20 corridor. Thus have
placed VCTS in the Metroplex TAF sites for the 21z through 00z
period.
58
&&
.PREV DISCUSSION... /ISSUED 400 PM CDT Sat Mar 25 2017/
Mostly sunny skies and pleasant temperatures prevail across North
Texas behind last night`s cold front. West-northwest winds have
ushered in some drier air making for a nice day across the region.
Temperatures are generally in the 60s and 70s with dewpoints in
the 40s.
Springtime usually means rapidly changing weather as the upper
pattern is usually fairly progressive. Tomorrow will be no
different. Shortwave ridging today and tonight will give way to a
fast moving shortwave trough by tomorrow and increasing severe
weather chances. As the upper disturbance approaches, rapid
surface cyclogenesis will commence during the morning hours. This
will result in strengthening southerly flow and a rapid northward
transport of moisture. By midday, surface dewpoints will likely
be near 60 degrees along the I-35 corridor toward to the Red
River. In addition, a dryline will advance eastward across West-
Central Texas.
By late afternoon, an elevated mixed layer will be in place across
North Texas resulting in a capping inversion around 800mb with
very steep lapse rates through about 500mb. Even as the main
shortwave tracks across northern Oklahoma, stronger forcing for
ascent will spread into North Texas by late afternoon. This should
help to lift the capping, which is not expected to be overly
strong. We`ll likely sample this with supplemental balloon data
tomorrow afternoon. The bigger concern regarding convective
development will be the quality and depth of moisture return into
the area given the northerly track of the shortwave. Surface based
instability is expected to be around 2000 J/kg with dewpoints in
the lower 60s, although this moisture is fairly shallow. Mean
layer instability (around 1500 J/kg) will likely be more
representative of the environment tomorrow afternoon from the
Metroplex and areas southward. Most of the high resolution
guidance develops convection to the west-northwest of the
Metroplex by 22Z, although these initial convective attempts
quickly diminish by 00Z. This suggests that the initial
development along the dryline may not have enough support to allow
them to move off the dryline into a more unstable environment.
Forcing will be stronger the farther north, so areas generally
north of I-20 should have a better chance for thunderstorms
through the early evening hours.
Our latest thinking is that the best chance for severe
thunderstorms in our area will be in the Red River counties,
particularly Cooke, Grayson, and Fannin counties, from about 22Z
to 00Z. However, it should be noted that if any storms farther
south can be sustained, then the environment is more than suitable
to support severe weather. Forecast soundings for tomorrow
afternoon feature lapse rates in excess of 8 C/km through a deep
layer along with large clockwise curved hodographs through the
lowest 2 km. While all modes of severe weather will be possible,
the quality/depth of moisture remains the biggest limiting factor
for a more appreciable tornado threat. Very large hail (baseball
size or larger) will be the main severe weather threat through the
evening hours. We`ll maintain 20-30% PoPs across mainly the
northern half of the CWA with the best chances along the Red
River. Any convection that develops will move east through the
evening with a cold front moving into the area during the
overnight hours.
Monday looks like it will be a rather nice day behind the cold
front but it won`t last long. Another strong upper low will
move into the southwest U.S. by Tuesday. This will again allow
moisture to spread northward and rain/storm chances increasing
late Tuesday through Wednesday. There may be an initial severe
weather threat late Tuesday afternoon/evening as convection
develops across West Texas along a dryline and moves eastward.
Rain/storm chances increase significantly across North Texas
Tuesday night into Wednesday where one or more rounds of
thunderstorms may move through the region. At this time, the
severe weather threat does not look overly impressive, although
there will be sufficient instability/shear to support rotating
storms during this time. We`ll monitor this closely over the next
48 hours. Heavy rainfall will be possible through Wednesday with
current forecast rainfall amounts between 2 and 4 inches across
parts of North Texas. While the system looks like it will remain
progressive enough to preclude a more significant flash flood
threat, localized training of storms would support flash flooding.
This system moves east Wednesday night into Thursday with quiet
weather through the end of the week.
Dunn
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 55 84 60 80 56 / 0 30 20 5 0
Waco 54 83 62 83 59 / 0 20 20 5 5
Paris 50 80 60 77 53 / 0 10 50 5 0
Denton 51 82 58 78 53 / 0 30 20 5 0
McKinney 49 81 59 78 54 / 0 30 30 5 0
Dallas 55 84 62 81 57 / 0 30 30 5 0
Terrell 50 82 62 79 56 / 0 20 40 5 0
Corsicana 54 84 63 82 60 / 0 20 30 10 0
Temple 57 84 60 84 60 / 0 20 10 5 5
Mineral Wells 52 86 54 80 53 / 0 20 10 5 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
58/24
Area Forecast Discussion
National Weather Service Hastings NE
1058 PM CDT Sat Mar 25 2017
.UPDATE...
Issued at 1058 PM CDT Sat Mar 25 2017
Updated to add drizzle to the forecast tonight.
UPDATE Issued at 824 PM CDT Sat Mar 25 2017
Updated the forecast to introduce areas of fog earlier this
evening for much of the CWA on the NE side. Visibility has been
jumping around, but am a bit nervous that we might need a Dense
Fog Advisory considering GLAMP and MOS data, and also HRRR model.
JYR dipped to 1/2SM mile for awhile, but has since come up to 2
SM. Will keep monitoring trends, but for now, will hold off on any
Dense Fog Advisory as we are not clearly tanking as of yet.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 231 PM CDT Sat Mar 25 2017
High Impact Weather Potential: Fog likely late tonight thru Sun
AM and it has potential to be dense (1/4SM vsbys or worse).
Aloft: A slow-moving low was over MO and a shortwave trof was
advancing thru the SW USA. This trof will kick the low NE tonight
with the intervening ridge moving over the fcst area (FA). The
trof will arrive tomorrow and track across the Srn Plns with a
small low moving E across KS.
Surface: The low pres sys that moved thru the last couple days to
the E. An axis of the high over Ontario/Quebec extended SW across
Neb into CO...while a cool front was making its way thru the Wrn
USA. High pres will remain overhead tonight. The front will cont E
with lee cyclogenesis occurring along the NM/CO border. The newly
formed low will head E tomorrow into Nrn TX. The Nrn portion of
the front will weaken and move into the FA as an inverted trof.
Now thru sunset: Mainly cldy...dry and chilly except over the Wrn
fringe of the FA where some sun has been/is occurring.
Tonight: Cldy/foggy. Areas that have seen the sun W of Hwy 183
will cloud-up. E-NE winds will advect the stratus W and this is
shown by all hi-res models.
Conds are ripe for fog. Low stratus has lingered thru the day for
most of the FA...keeping temp-dwpt depressions low and BL flow is
from the NE where it has been raining today...meaning that
incoming air is very moist.
There is potential for dense fog...but there are a couple
mitigating factors that reduce confidence: 1) the invasion of
thick multi-layered mid-high clouds from the W which will reduce
radiational cooling. 2) Where stratus remains locked in...does it
build down low enough for 1/4 SM vsbys?
Sun: Cldy/foggy thru the AM and the low clds will probably last
well into the day. They will be hard to get rid of with contd E-NE
low-lvl flow. Expect some erosion/dissipation will occur W of Hwy
281...but even still it will only reveal multi-layered mid-high
clds.
Used consensus of model 2m temps for high which does well in
these situations. That kept areas N and E of the Tri-Cities the
coolest.
A bit of -RA will move into the SW 1/3 of the FA after 3 PM on
the N side of the low moving acrs KS.
.LONG TERM...(Sunday night through Saturday)
Issued at 231 PM CDT Sat Mar 25 2017
High Impact Weather Potential: None currently envisioned outside
of probable aviation concerns with IFR conds expected Wed-Thu.
We have are currently in a window of opportunity for increased
legitimate precip chances and it will last for about the next 10
days before ensemble means hint at a return to NW flow.
Aloft: A shortwave ridge will move thru Mon ahead of the next
trof moving onshore and digging into the Desert SW. The flow aloft
will turn SW Tue as a newly formed low progresses from AZ into
NM. It is a good sign that this low is fcst to be a slow-mover
...lifting into the TX panhandle Wed and then across KS Thu to be
somewhere near MCI by 00Z/Fri. As is predecessor...this low will
get kicked NE as another low forms over the Wrn USA and drops into
the Desert SW Fri. So a ridge should be overhead Fri. There are
indications from the last 2 runs of the GEM/EC/GFS that this low
might cut-off over the Mex-AZ-NM border. But the EC ensemble mean
suggests it could lift NE into the Plns as well. Plenty of time
btwn now and then to iron out the details.
Surface: Canadian high pres will cont to nose S into the FA Mon-
Tue while the next Pac cool front progresses thru the Wrn USA. But
cyclogenesis will commence over NM. This low too will head E
across the Srn Plns Wed-Thu and then head toward the GtLakes Fri.
An inverted trof N of this system will move into the FA Tue night.
Weak high pres will slowly build into the rgn Thu-Sat.
Precip: The shield of RA will move out Sun night...mainly
affecting N-cntrl KS. Parts of the FA have the potential to get
drenched with more much-needed rainfall Wed-Thu. Amts depend on
where the def zone sets up and pivots or become stationary for a
while. Still no thunder in the fcst. We`d need a diff track. Can`t
entire full out a strike or two...but evidence is not strong
enough that sufficient instability will exist.
Temps: Near normal Sun. A little above normal Mon-Tue. We are
probably too high Wed-Thu with periods of RA and heavy/thick
cloud cover. These days should both be cooler than normal. Fri-Sat
back to near normal.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday evening)
Issued at 652 PM CDT Sat Mar 25 2017
Biggest challenge will be determining how fast visibility
decreases tonight. Observation from KGRI just came in at 2 1/2SM,
so I might very well need to update soon. Numerical models
indicate that ceilings should continue to low as stratus works its
way toward the surface, and expect LIFR ceilings by overnight,
along with fog developing as well.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
UPDATE...Heinlein
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Heinlein
Area Forecast Discussion...UPDATED
National Weather Service Grand Junction CO
801 PM MDT Sat Mar 25 2017
.UPDATE...
Issued at 801 PM MDT Sat Mar 25 2017
Latest satellite imagery shows the upper level trough and cyclonic
rotation moving east-southeast across southern UT. Lightning has
been active under the center and to the east and south of the
trough and was observed as far north as just west of Canyonlands
Airport in the last hour. One band of clouds and associated virga pushed
north over western CO and eastern UT late this afternoon and
early this evening and helped to moisten up the lower levels.
Light rain has been observed at many locations along and north of
I-70 in the last couple of hours and snow was observed at 10,000
feet on Hwy 65 over the Grand Mesa. Cooling cloud tops continue to
expand ahead of the base of the trough over the Four Corners and
toward the San Juan Mtns. Latest RAP model indicates best and
highest precip chances over the San Juans and toward the NM border
between 10 pm and 4 am. During this time the snow level will also
be dropping to near 8000 feet, before dropping possibly as low as
6500 feet by sunrise. The Winter Weather Advisory looks on track
for 4 to 8 inches above 9500 feet and lesser amounts at the lower
elevations. Forecast has been updated to support current and near
term trends, especially to increase PoPs across the southern
areas. A pretty sharp back edge to the mid to upper level QG
forcing should bring an end to the significant precipitation by
sunrise.
&&
.SHORT TERM...(Tonight through Sunday night)
Issued at 144 PM MDT Sat Mar 25 2017
A fast moving and vigorous Pacific storm was tracking eastward
across the Desert Southwest spreading clouds over the forecast
area. Radar hadn`t detected more than an area of virga over
eastern Utah`s Grand Flat region so far this afternoon, but that
should change as the system draws closer.
The latest forecast models take the open wave trough eastward
across the area tonight. The bulk of the energy associated with
the trough will pass just south of the Four Corners from late this
evening into the early morning hours. A nice Div-Q couplet in the
base of the trough combined with divergence aloft and orographic
lift favors precipitation over the San Juan Mountains. Dynamics
may be sufficient to generate isolated thunderstorms over portions
of southeast Utah and southwest Colorado. QPF output from latest
models higher than previously forecast and doesn`t seem
unreasonable, though there may be some convective feedback in the
NAM12 solution. Consequently, boosted QPF numbers in the San Juan
Mountains with this package which increased snow amounts to low
end advisory amounts.
Limiting factor with this event will be the warmth ahead of the
trough which will limit accumulations this evening, and the short
duration of this event. Temperatures suggest the snow level will
be near 9500 feet at 6 PM this evening, but will lower to near
6500 feet around sunrise on Sunday. As a result, significant
accumulations are likely to be limited to areas above 9500 feet,
or from 4 to 8 inches with locally higher amounts, and from 1 to 4
inches from 8000-9500 feet, and from trace to an inch from
6500-8000 feet along the slopes of the San Juan Mountains. Given
the previous, hoisted a winter weather advisory for the San Juan
Mountains above 9500 feet from 6 PM this evening through 9 AM
Sunday morning. Main concern is snow impacts on the high passes
where road conditions will deteriorate and visibility will become
limited.
Surrounding mountain areas will also see snow, but accumulations
will largely range from 3 to 5 inches with locally higher amounts
on top of the Grand Mesa and into the Sawatch and West Elk ranges.
Instability showers will continue along the Continental Divide
Sunday, but additional accumulations are expected to be light and
localized. Diurnal cooling and drying will bring an end to shower
activity Sunday evening.
Forecast lows tonight should be milder due to cloud cover. An
influx of cooler air will bring afternoon highs down a few degrees
Sunday, but temperatures will remain above normal. Colder
temperatures are on the horizon Sunday night, though freezing
temperatures in areas where tender vegetation has budded is
unlikely.
.LONG TERM...(Monday through Saturday)
Issued at 144 PM MDT Sat Mar 25 2017
As mentioned in previous discussions, the progressive spring
pattern will continue during the coming week. After a brief break
in activity showers and embedded thunderstorms are expected to
develop over much of the region Monday afternoon ahead of the
next Pacific storm.
Latest models were in much better agreement with the evolution
and track of this system. From late Monday afternoon through
Tuesday morning, models deepen the trough over the western Great
Basin forming a closed low over central Arizona. From there, the
low center drifts slowly eastward arriving over the Texas
Panhandle Wednesday afternoon. During this period the forecast
area will fall under the col area between the storm to the south
and the northern atmospheric stream. As a result, expect unsettled
conditions to continue through Tuesday night with isolated
thunderstorms during the afternoon. Mountain snow accumulations
may be sufficient for additional winter weather advisories during
the early part of the week.
A transient ridge will allow a return to quiet weather Wednesday
and most of Thursday. Thereafter, another closed Pacific low
pressure system will begin to impact the area. Model agreement
isn`t as good as with the system discussed previously for the
early part of the week, so difficult to sort out the details with
this next storm with much confidence. At this point it seems fair
to expect unsettled conditions during the latter part of the week.
Expect a bit of roller coaster where temperatures are concerned,
but variances aren`t expected to be profound from one day to the
next.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 503 PM MDT Sat Mar 25 2017
Mostly cloudy skies and plenty of virga seen across the area this
afternoon. Scattered rain and snow showers have also already
developed, generally confined to the higher terrain ATTM. Showers
will increase in coverage and spread into some valleys into the
evening with the best chance tonight through Sunday morning as a
disturbance tracks across the region. The San Juans will be
favored during this event with periods of reduced cigs and vis and
obscured mountain tops overnight. Lower valley TAF site cigs
should stay above ILS breakpoints but higher TAF sites like KASE
and KTEX will drop down to MVFR or even IFR at times during
heavier showers. Activity will decrease after 18Z tomorrow with
just some lingering orographic showers as drier air works back
into the region.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 9 AM MDT Sunday for COZ018-019.
UT...None.
&&
$$
UPDATE...BM
SHORT TERM...NL
LONG TERM...NL
AVIATION...MMS
Area Forecast Discussion
National Weather Service Green Bay WI
1006 PM CDT Sat Mar 25 2017
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 225 PM CDT Sat Mar 25 2017
The latest RAP analysis and satellite/radar imagery show an area of
low pressure spinning along the Kansas/Missouri border, and an
associated warm front extending eastward across central Illinois to
northern Pennsylvania early this afternoon. Band of light rain
north of this boundary has been creeping northward across southern
Wisconsin, and should reach the southern Fox Valley later this
afternoon. Meanwhile, a potent Canadian high pressure system has
been feeding dry air into northern WI, which has kept temperatures
in the 30s. Though partial clearing has pushed its way into northern
Lake Michigan, widespread overcast conditions continue. As the low
pressure drifts northeast over the next 24 hours, precip trends and
potential for freezing rain across northern WI are the main forecast
concerns.
Tonight...Occluded low pressure will slowly chug its way northeast
across the central Mississippi Valley while a strong Canadian high
will exit over Quebec. The waning influence of the high will allow
for increasing moisture transport from north to south across the
state during the evening, highest over eastern WI within the warm
conveyor belt. Ample dry air in the mid-levels will keep the precip
at bay across the north until late in the evening or early
overnight, but the most persistent precip will occur over eastern
WI. Despite the late arrival of the precip, the threat of freezing
rain remains over north-central WI. Dewpoints didnt fall off much
this afternoon, so temps should not fall much due to evaporative
cooling. However, even with min temps in the 30-32 degree range,
not comfortable going without a freezing rain advisory tonight
across the north with precip amounts upwards of a tenth of an inch.
With coordination from MQT will hoist an advisory from late this
evening until 9 am Sunday morning.
Sunday...The low pressure system will continue to drift closer to
the region into the southern Great Lakes. Though the main slug of
moisture shifts towards the lower peninsula of Michigan during the
day, progged soundings continue to look saturated at most locations
during the morning, which should be good for occasional light rain
and drizzle. The chance of precip should diminish some during the
afternoon from west to east as the deepest saturation exits to the
east. With the widespread clouds, rain, and northeast to north
winds, temps should only rise into the upper 30s to middle 40s.
.LONG TERM...Sunday Night Through Saturday
Issued at 225 PM CDT Sat Mar 25 2017
As the current low pressure system delivering precipitation to
Northeast Wisconsin moves northeast through the Great Lakes and
out of the region, another low will sweep by to our south. This
second low will move east into the Ohio Valley during the first
half of the work week and is not expected to deliver much, if any,
precipitation to Northeast Wisconsin. Some cloudiness is possible,
but skies should become mostly clear for the latter half of
Tuesday and most of the day Wednesday.
The next low pressure system to impact Northeast Wisconsin will
develop over the Southwest U.S. on Wednesday and move into the
Midwest by Friday. This system has potential to deliver heavy rain
to our area at times into next weekend as it phases north. The low
will not be particularly effective at tapping cold Canadian air,
so precipitation should remain liquid for the most part. Any
freezing rain should be limited to Northern counties during
nighttime hours when coldest temperatures occur, producing
scattered slippery spots.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1006 PM CDT Sat Mar 25 2017
Ceilings and visibilities lowering as expected across the far
north as scattered rain has moved in. Some surface icing possible
over far northern WI, including RHI, as temps near freezing in
spots. IFR conditions will continue through late Sunday afternoon.
Some improvement in cigs expected Monday as somewhat drier air
moves in.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 AM CDT Sunday for WIZ005-010>012.
&&
$$
SHORT TERM.....MPC
LONG TERM......ML
AVIATION.......JKL
Area Forecast Discussion
National Weather Service Wilmington OH
958 PM EDT Sat Mar 25 2017
.SYNOPSIS...
Southerly flow ahead of low pressure will provide warm
temperatures and mainly dry weather this afternoon. Showers and
a few thunderstorms will develop tonight through Sunday as the
area of low pressure approaches from the west. Another upper
level disturbance will then move across the area Monday
afternoon into Tuesday providing a continued chance of showers
and thunderstorms for the area.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A weakening area of showers stretching from central Indiana into
central Kentucky has been progressing very slowly eastward this
evening. The latest HRRR is showing this pcpn continuing to
weaken as it spreads into our western areas tonight. A better
chance of showers will work into our southwest late tonight
ahead of a stronger vort axis that will pivot up toward our
area. Have made some tweaks to the pops to slow down the pcpn a
few hours. Instability will be marginal at best overnight and
this should help limit any thunder.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Later Sunday morning the upper level low will take on a negative
tilt as it pulls northeast towards the Great Lakes. As this
happens low level temperatures will fall and work together with
daytime heating to steepen low level lapse rates. NAM forecast
soundings are showing MUCAPE values around 1000 J/kg while the GFS
is showing values slightly higher, around 1200 J/kg. At the
same time areas of PV will be rotating around the upper level
low providing a source of lift. In general, global and high res
models are indicating the best lift across our eastern zones
Sunday afternoon with a secondary source of PV in association
with the low moving into the western zones. Forecast soundings
on both the NAM and GFS have k index values in the low 30s
Sunday afternoon with LI values briefly turning negative. PWATs
at this time are also around 1.00". Due to the ample moisture,
sufficient lift, and instability have kept likely PoPs or
greater for Sunday afternoon. It should also be noted that at
this time 0 - 3km bulk shear is around ~30kts. Thanks to the
shear, instability, low level lapse rates SPC has the area in a
marginal risk for isolated small hail and gusty winds.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Showers and thunderstorms will taper off Sunday night as an
upper level disturbance moves to the east. There will be a lull
in the precipitation for much of the day on Monday before an
upper level disturbance moves through Monday night into Tuesday.
Precipitation will taper off Tuesday night. Moisture will be
trapped across the area for Wednesday therefore increased sky
cover and decreased temperatures some for Wednesday.
The next system will begin to bring rain shower chances to the
region on Thursday. Precipitation is expected to become more
widespread Thursday night into Friday as a low pressure system
nears the region. A cold front will move through Friday night.
Precipitation chances will begin to decrease after the passage
of this feature.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
The leading line of showers and embedded thunderstorms is
currently stretching from central Indiana down into central
Kentucky. This line has been making a very slow eastward push
and as we start to lose some of the diurnal heating, expect to
see some weakening as it finally pushes into our western areas
later this evening. As a result, will just allow for a vcsh
late this evening and into the early morning hours at the
western taf sites. A stronger mid level vort axis will rotate
up across the area from the southwest late tonight into Sunday
morning, eventually allowing for more widespread showers to
develop from southwest to northeast. This should also allow for
cigs and possibly vsbys to trend down into MVFR as we progress
through Sunday morning. Instability remains fairly limited
through the morning hours so think thunder chances will remain
low enough to leave mention of thunder out of the TAFS through
the morning. As we better destabilize through the afternoon
hours, will go ahead and include a vcts to cover the thunder
threat.
OUTLOOK...MVFR ceilings and visibilities will be possible late
Monday into Tuesday morning.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Haines
NEAR TERM...JGL
SHORT TERM...Haines
LONG TERM...Novak
AVIATION...JGL
Area Forecast Discussion
National Weather Service Jackson MS
927 PM CDT Sat Mar 25 2017
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
Things are beginning to quiet down following an active morning and
afternoon across much of the area. Latest surface analysis shows a
cold front centered along the MS river and slowly moving east.
Meanwhile, a closed mid- and upper-level low was centered over
central MO with the an associated trough axis oriented through the
lower MS river valley. After this morning`s squall line moved
through the atmosphere was able to destabilize enough ahead of
the approaching cold front to support additional thunderstorms
mainly north of I-20. Enough shear was juxtaposed with a tongue of
diurnally enhanced instability for isolated supercell structures
to be realized with an attendant hail and wind threat through the
late afternoon hours. However, this activity has quickly weakened
following sunset and a loss of diurnal heating. As of 2z, a few
scattered showers and thunderstorms remain oriented SW to NE from
TVR to CBM.
For the remainder of the overnight period, expect
this scattered shower and storm activity to continue to move east
with the main focus for a shower or two becoming more oriented
across the SE portions of the CWA. Any lingering lightning should
dissipate quickly as convection continues on a downward trend. Our
attention now turns to the potential for fog development across a
good portion of the CWA. Latest hi-res guidance is fairly
aggressive with low visibilities, especially across the SE,
however confidence is not as high right now given that 1) there`s
lingering cloud cover, 2) winds could stay just high enough to
limit widespread dense fog, and 3) exact location of the cold
front. Given these uncertainties will hold off on mentioning fog
in the HWO for now and will keep patchy dense fog wording in the
SE with regular patchy fog elsewhere ahead of the front and will
let the next shift monitor the trends for future updates. In terms
of min temps, went a degree or two cooler in the NW for areas
that have the best chance of cooling behind the front and kept
temps more mild everywhere else. /TW/
Prior discussion below:
Tonight and Sunday: Visible satellite imagery this afternoon showing
cold core low spinning about over the northern Ozarks. Meanwhile,
down in our neck of the woods, the majority of this morning`s
convection has moved to the east and southeast, but other storms
have developed lately over north and west central sections of MS.
These storms are developing in a confluent area of mid 60s
dewpoints that have combine with heating to produce CAPEs around
1000 j/kg. Some of these have had robust updrafts and have produce
some hail.
The HRRR is showing these storms maintaining themselves for the rest
of the afternoon with the possibility of a few more severe storms.
Also, the convective area over the southeast looks to spread out to
the northeast before moving into AL this evening. and only a few
light showers left by midnight. With low level moisture hanging
around overnight, fog looks like a good bet after midnight as skies
clear.
Surface winds never drastically change directions, thus southerly
flow Sunday will begin quickly reloading the moisture levels in the
lower levels ahead of a storms system slated for Monday. Low to mid
60s dewpoints look to overspread the area by 12Z Monday./26/
Monday through Friday: A generally active weather pattern will
remain in place through the remainder of the forecast period
thanks to a progressive upper level pattern. The next system of
interest is still on track for Monday, as a mid level shortwave
and surface low track across the Mid South. Moderate instability
is expected across our area, along with decent height falls
occurring with the passage of the wave. Given the timing of the
system (peak heating/instability) and anticipated steep lapse
rates, a respectable severe weather threat will exist with
somewhat greater potential farther north in the area closer to the
better forcing. The currently advertised slight/marginal risk
areas may need to be tweaked upward in later forecasts for some
portions of the area.
The surface baroclinic zone associated with Monday`s system will
stall just north/northwest of the CWA, keeping most or all of the
forecast area in a warm/moist environment into the middle portion
of next week. This will keep lower end chances for less organized
showers/storms around Tuesday into Wednesday even as shortwave
upper ridging passes across the area. The next system of interest
is still on track to arrive around the Thursday time frame. Some
model inconsistencies exist with respect to the nature of this
system (slower moving cut off upper low vs more progressive upper
wave). Nevertheless, the soupy airmass will remain in place ahead
of this system, and another increase in rain/thunderstorm chances
appears to be a good bet. Stronger deep layer shear will accompany
this system, and there are indications that steep lapse rates
will once again be possible. Particularly once we begin to see
better model consistency, there is a good chance that severe
potential will need to be added to HWO and graphics products for
this period of the forecast. There is a better chance of an actual
frontal passage with the late week system, suggesting a break in
the rain is possible by next weekend. /DL/
&&
.AVIATION...
00Z TAF discussion: A line of tsra continued from nw of HKS ne
across GTR at 2330Z. This line wl dissipate by 01z but an
isolated shra or two wl remain possible over east MS tonight.
Elsewhere, mostly clr skies wl allow fog development reducing
vsbys to MVFR after 06z and IFR/LIFR by 11Z, especially over se
MS. VFR conds are expected Sunday after 15Z and wl prevail into
Sunday evening. /22/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 60 82 63 82 / 26 3 9 58
Meridian 59 83 63 81 / 30 15 8 37
Vicksburg 55 82 63 82 / 27 2 7 58
Hattiesburg 61 84 64 82 / 30 14 8 28
Natchez 60 83 64 82 / 19 3 7 47
Greenville 52 79 63 78 / 1 2 15 61
Greenwood 56 79 62 80 / 5 2 12 63
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
TW/DL/22/26
Area Forecast Discussion
National Weather Service Blacksburg VA
1033 PM EDT Sat Mar 25 2017
.SYNOPSIS...
High pressure is off the coast in the western Atlantic, stretching
back across the southeastern states. A deep area of low pressure
will drift east over the Midwest tonight with a trailing cold south
into Louisiana. A warm front will reside from the Great Lakes region
to Lake Erie into Sunday.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 955 PM EDT Saturday...
Satellite fog product showed some breaks in the high clouds over
the mountains this evening. Seeing some low clouds forming on
the eastern slopes of the Blue Ridge as far north as Watauga
and Wilkes county. Models showed these lower clouds expanding
northeast after 06Z/2AM. HRRR and other Hi-Res guidance have
been consistent in bringing higher probability of precipitation
into the mountains around 12Z/8AM. Have trimmed back chance of
showers before then. Also adjusted low temperatures in a few
locations mainly based on the expected cloud cover.
An upper level ridge off the southeast coast will continue to play
blocker and divert a closed low over the Midwest toward the Ohio
Valley through Sunday. Meanwhile, a dry surface high pressure system has
moved off into the western Atlantic, however it remains stretched
back over the southeastern US. The combination of these two stable
high pressure systems will keep the area dry into tonight. As the closed
low enters the Ohio Valley tomorrow morning, prefrontal showers will
slowly move eastward through the day. Rain showers will cross over
the mountains in the morning, then over the foothills in the
afternoon. By late afternoon and into the evening, these showers
will track across the piedmont. Lingering stable surface high will
still cover the area east of the Blue Ridge in the morning and into
parts of the afternoon. This will limit storms from becoming to
strong in the afternoon and reduce rainfall amounts. Some wind gusts
up to 35 mph are possible in isolated stronger storms but chances
are very low.
Southerly flow around these systems and a slower entry of showers
into the area will help Sunday temperatures warm into the lower to
mid 60s across the mountains. With the later arrive of rain east of
the Blue Ridge, temperatures will be able to warm into the low to
mid 70s.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 330 PM EDT Saturday...
Upcoming week will be active nationwide as series of Pacific
Low pressure systems propagate east across the CONUS. Leading
system will be weakening as it moves northeast around the
periphery of an upper level ridge of High pressure over the
western Atlantic early Monday. A second shortwave will be close
on the heals of the first, passing across the area Monday night
into Tuesday. The overall result will be a threat for showers
and isolated thunderstorms across our region from Sunday night
through Tuesday night...qpf averaging about a quarter to a half
of an inch.
In spite of the weather being somewhat unsettled, it will be
mild with temperatures running about 15 degrees above normal.
Can`t rule out a strong thunderstorm or two Monday, but overall
dynamic support appears to be lacking for anything organized.
Tuesday`s trough passage may come through early enough to
preclude an organized severe threat for our CWA, except for
maybe the Piedmont. Instability and moisture are significantly
more abundant Tuesday compared to Monday, but favoring the
Piedmont and Tidewater where there will be higher CAPE and
and better dynamic support aloft.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 400 PM EDT Saturday...
Behind the Tuesday system, we will see a brief respite from the
parade of storm systems as an area of high pressure from Canada
filters southward into the area stabilizing and cooling the air
mass. This should lead to a relatively precipitation free and
slightly cooler period. Cannot completely rule out some light
showers due to weak ripples in the flow aloft. Temperatures and
dewpoints will drop about 10 degrees from the Mon-Tue period.
By Friday, the next, and fairly potent, upper low tracks toward
the area. However, there is considerable discrepancy between
the GFS and the ECMWF in the configuration and timing of this
system into the eastern U.S. The GFS depicts more of an open
wave reaching the CWA as early as Thursday night moving east of
the area by Friday afternoon. Meanwhile, the ECMWF is much
slower, deeper, and further south with a cutoff upper low
lifting it slowly north-northeast into the Ohio Valley by late
Friday. The difference between the two models can be accounted
for in noting the strength and blocking of an upstream ridge
across the Atlantic. This upstream ridge is much stronger per
ECMWF, which also depicts a notable wedge down the east side of
the Appalachians as the closed low lifts north into the Ohio
Valley. The ECMWF would result in a much wetter and stormier
pattern for the CWA, although it would not arrive until Friday
as opposed to Thu night per GFS. For now, have generally broad
brushed the area with high chance to likely pops beginning Thu
night and continuing into Friday. In addition to the differences
noted above, there are also massive differences between the two
models regarding instability and the potential for severe, with
the ECMWF much more noteworthy in this category. For now, have
included a chance for thunder without any further details. It
will likely take several runs for the models to resolve their
differences on this system. Another system is slated to follow
by the end of the weekend or the beginning of the next week, so
the active pattern is expected to continue into the next week.
Temperatures will be closer to normal Wed-Thu, then begin to
trend back to above normal levels Fri-Sat.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
As of 709 PM EDT Saturday...
Generally VFR through the TAF period. For tonight, expect a
continued stream of cirrus clouds for the terminals. If there is
an area of lower MVFR stratus it would be along the southern
Blue Ridge into northwestern North Carolina after 05z given
increasing moisture levels and winds backing to light
southeasterly. That would lead to obscured mountain ridges, but
confidence is low that such cloudiness would affect either
Roanoke or Danville. South winds 6-8 kts become southeast 3-6
kts overnight.
Expect increasing BKN/OVC VFR cloudiness early Sunday morning,
building eastward from west to east. Appears per recent high-
resolution guidance that the earliest that showers would affect
our western airports would be during the afternoon (after 17z).
Potential for isolated thunder in the showers as well but only
limited coverage. Left out of the TAFs given uncertainty at this
late range. Ceilings/visibility should remain VFR, though
potential brief MVFR visibility in steadier showers. Southeast
winds Sunday morning increase and become southerly 6-10 kts.
Extended Aviation Discussion...
An active weather period with a series of vigorous upper-level
low pressure areas tracking from west to east across the U.S.
during the week. Showers and a few thunderstorms will overspread
the area Sunday with the first system with widespread sub-VFR
cigs/vsbys in clouds and precipitation. Monday the area will be
between systems, but a moist/unstable air mass will remain in
place and widely scattered showers and isolated thunderstorms
are possible. Areas of sub-VFR cigs/vsbys are also possible,
especially during the morning hours, in low clouds and fog. The
next upper-level low will arrive Tuesday with another chance for
showers and thunderstorms along with periods of sub-VFR
conditions. Wednesday-Thursday may bring a period of improved
aviation conditions as a weak cold front temporarily pushes the
deeper moisture south of the area. However, by Friday the next
in the series of upper-level systems arrives with another chance
for showers, thunderstorms, and sub-VFR conditions.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...RCS
NEAR TERM...AMS
SHORT TERM...PM
LONG TERM...RAB
AVIATION...AL/RCS