Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/26/18
Area Forecast Discussion
National Weather Service Cheyenne WY
744 PM MDT Sun Mar 25 2018
.UPDATE...
Issued at 739 PM MDT Sun Mar 25 2018
Decided on a Winter Weather Advisory for the I-80 Summit this
evening. WYDOT observations showing visibilities anywhere from 1/4
to 1/2 mile in moderate to heavy snow. Radar has a band of
moderate reflectivity right over the Summit and IR imagery showing
cooling cloud tops southwest in northern Colorado. Believe it will
be short lived as better lift moves north, but did not want to
chance it as there is a lot of traffic seen on webcams. Updates
have been sent.
&&
.SHORT TERM...(This evening through Monday)
Issued at 257 PM MDT Sun Mar 25 2018
Was tempted to take thunder out of the forecast on the afternoon
package, however LAPS data still showing a solid 200-400 j/kg of
CAPE across our central zones and higher res satellite imagery
confirms that we do have some taller buildups in that area and IR
imagery shows cooling cloud tops ahead of the initial shortwave
moving through the central Rockies. As the initial shortwave
drives east this evening, we will get a push of colder air late
tonight with 700 MB temps falling to around -8C where we have the
Winter Weather Advisory posted. Latest model ensembles still
advertise the heaviest snowfall tonight into Monday to occur just
to the north of our area, but there is still a chance that we
could see localized 4 to 7 inches on ridges and mountains across
northern Carbon and Albany counties as well as closer to the
heavier band of snow that will cross extreme northwestern Converse
county. So, with that we will keep the Winter Weather Advisory
posted where the midnight shift had it for.
.LONG TERM...(Monday night through Sunday)
Issued at 257 PM MDT Sun Mar 25 2018
Precipitation will gradually taper off Monday with the next chance
of precipitation still expected to move in from the north on
Wednesday along a cold front. No changes from the midnight shift.
/JG
Long range models in agreement with the overall pattern, which
suggests a prolonged period of unsettled weather across southeast
Wyoming and western Nebraska through the week. Models and
ensembles are struggling with the timing of the shortwave activity
expected to push across the area for mid to late week, which is to
be expected several days out. All models show progressive
northwest flow on Wednesday as the first wave moves across
Wyoming. Decent dynamic forcing, llvl, and unstable conditions
may lead to rain/snow showers changing to all snow through the
afternoon and evening hours on Wednesday. Exact timing is tough to
pin down at this time, but evening rush hour impacts are
possible. Soundings show pretty unstable conditions along the cold
front as it stalls across the mountains, so will need to monitor
the potential for heavy snow showers or snow squalls through
Wednesday evening. Increased POP between 50 to 70 percent,
especially along the I-80 corridor and in the mountains. High
temperatures will be tricky to forecast on Wednesday, due to the
timing of the cold front in addition to wet-bulb cooling once any
precipitation develops. Highs in the 40`s are possible before
temperatures rapidly fall into the 30`s and even upper 20`s late
in the afternoon.
Models indicate the first shortwave progressing southward early
Thursday morning, with a few more disturbances embedded in the
northwest flow aloft rapidly moving southeast across the region.
Can not rule out a continuation of snow and rain showers through
early Friday morning. For the weekend, the GFS and Canadian show a
cold and snowy pattern for the area as an arctic cold front stalls
across the mountains, and the main upper level trough digs further
to the west as it slowly translates southward. The ECMWF is more
zonal with the upper level pattern and doesn`t show nearly as much
activity, while the ensemble forecasts lean towards the GFS and
Canadian. Increased POP slightly next weekend, but kept
temperatures in the 40`s to mid 50`s during the day. /TJT
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 511 PM MDT Sun Mar 25 2018
Widespread IFR event taking shape east of the Laramie Range out
into the Nebraska Panhandle this evening as a low pressure center
brings widespread moisture to the area. Easterly upsloping winds
are expected to bring IFR ceilings into the Panhandle around 03Z
with possibility of LIFR in fog/snow after 06Z tonight. Used
latest HRRR for guidance on onset and duration of IFR/LIFR
conditions. Will continue to monitor.
&&
.FIRE WEATHER...
Issued at 257 PM MDT Sun Mar 25 2018
No changes for the afternoon update. /JG
No fire weather concerns over the next several days. Gusty wind is
possible at times, but RH values should remain well outside of our
critical thresholds. Expect scattered showers & thunderstorms this
afternoon/evening, and accumulating snow over northern areas later
tonight and early Monday. /CLH
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory until noon MDT Monday for WYZ101-102-104.
Winter Weather Advisory until 2 AM MDT Monday for WYZ116.
NE...None.
&&
$$
UPDATE...GCC
SHORT TERM...JG
LONG TERM...JG/TJT
AVIATION...GCC
FIRE WEATHER...JG/CLH
Area Forecast Discussion
National Weather Service Sioux Falls SD
910 PM CDT Sun Mar 25 2018
.UPDATE...
Issued at 904 PM CDT Sun Mar 25 2018
Expanded the winter weather advisory for freezing rain and
freezing drizzle about one row of counties westward including
Minnehaha county. Temperatures in the new headlined area are
running one to two degrees cooler than previous forecast, and the
HRRR and RAP are keeping temperature readings very close to
freezing tonight through mid morning Monday. The ice may be rather
soft on road surfaces, and treated road surfaces will likely be in
good shape. But elevated surfaces, sidewalks, driveways, etc.,
will likely get pretty slick.
The worst of the icing is expected in southwest MN and Brookings
county SD where temperatures will hover in the upper 20s to near
30 degrees. There may be some melting in southwest MN Monday
afternoon, only to refreeze again Monday evening.
&&
.SHORT TERM...(This evening through Monday)
Issued at 330 PM CDT Sun Mar 25 2018
Complicated forecast tonight and Monday, as precipitation develops
and expands across the region in response to a broad mid-upper level
trough swinging out of the Rockies. Confidence in precipitation
occurring is pretty high, but precipitation type is much less so.
Still seeing some issues with saturation aloft leading to potential
for drizzle instead of bonafide rain/snow at times. For this, leaned
more heavily on GFS/NAM projections of saturation in the critical
ice-bearing layer, but even with this, there are areas where ice
introduction will be lacking at times over the next 24 hours.
Also have a warm layer aloft which will limit snowfall south of
Highway 14, but in turn will contribute to the potential for
freezing rain/drizzle in areas where surface temperatures remain
near freezing for several hours. This appears to be most likely in
areas east of a line from Brookings-Luverne-Storm Lake, particularly
in the more elevated areas of southwest MN, and feel confident
enough in icing potential in these areas to issue a Winter Weather
Advisory for freezing rain in these areas from late this evening
through Monday. Advisory may need to be expanded by later shifts if
confidence in icing farther west grows. Travel impacts of icing may
be alleviated for a time during the afternoon, when road temps could
rise above freezing, but this will not help impacts to trees and
potentially power lines, so will run the advisory all the way
through the afternoon, and into the evening when precipitation
should be diminishing west to east.
Enough energy/elevated instability above the deep isothermal layer
across our southeast by midday/afternoon to include a mention of
thunder for most of northwest Iowa, and nearby areas of extreme
southeast South Dakota/northeast Nebraska. Fortunately, temperatures
at the surface in these areas should be warm enough to minimize the
risk of convective freezing rain.
.LONG TERM...(Monday night through Sunday)
Issued at 330 PM CDT Sun Mar 25 2018
The extended forecast begins with wintry precipitation continuing in
our eastern zones as the main wave finally begins to push through.
Exact precipitation type remains a source of contention at this
time. Profiles struggle to become saturated above the -10C level,
suggesting type will not include snow. Lack of a deep cold layer
near the surface seems to mostly rule out sleet. Surface
temperatures across northwest Iowa look to be just above freezing,
so will anticipate rain there. Southwest Minnesota could have
lingering freezing rain as temperatures may hang back just below
freezing there. Either way, precipitation should end by 06z Tuesday.
While the main wave passes Tuesday, flow aloft remains somewhat
zonal in its wake, which will actually allow a slight warming trend.
We`ll be under the influence of the left entrance region of a jet
streak and will remain dry thanks to large scale subsidence.
Thermodynamic profiles appropriately dry out pretty quickly by
Tuesday afternoon, allowing our ever improving sun angle to help
us heat up.
Wednesday, a slight disturbance will induce southerly flow early
before a cold front passes early in the afternoon. PV and isentropic
fields imply there will be decent lift with this disturbance. While
moisture profiles are marginal, could easily see some spotty rain,
especially in our south. There does seem to be enough of a pressure
gradient to drive some mixing that may be able to access warmer air
aloft even after the surface front passes. Bumped up winds and high
temperatures accordingly.
The upper flow starts to become more amplified for Thursday/Friday
with slight disagreements amongst guidance. Best chances are Friday
night with temperatures cool enough to support another chance for
snow across the region as April approaches.
Zonal regime returns by the weekend, keeping our temperatures at or
slightly below normal with stubborn lingering chances for
precipitation.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 633 PM CDT Sun Mar 25 2018
IFR to LIFR conditions will be common for the area through the 00Z
TAF period. The best chance for a freezing rain, or a rain and
freezing rain mix, will occur at KFSD late tonight and early
Monday. There could also be isolated thunderstorms at KSUX Monday
afternoon but the chances of that happening at a specific point
location are too remote to include at KSUX at this time.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 10 AM CDT Monday for SDZ055-056-
062.
Winter Weather Advisory until 1 AM CDT Tuesday for SDZ040.
MN...Winter Weather Advisory until 10 AM CDT Monday for MNZ098.
Winter Weather Advisory until 1 AM CDT Tuesday for MNZ071-072-
080-081-089-090-097.
IA...Winter Weather Advisory until 10 AM CDT Monday for IAZ001>003-
013-014-021-022.
NE...None.
&&
$$
UPDATE...MJ
SHORT TERM...JH
LONG TERM...Ferguson
AVIATION...MJ
Area Forecast Discussion
National Weather Service Fort Worth TX
1002 PM CDT Sun Mar 25 2018
.UPDATE...
As is usually the case nocturnally in the spring and early summer
months, the surface dryline and associated surface low continue
to retrograde back westward toward the better mid level height
falls across eastern New Mexico and West Texas. Temperatures
ranged from the 60s across the northeast counties, to the 70s
elsewhere under considerable, multi-level cloudiness streaming
within strong southwest flow aloft over the area.
After a vigorous supercell with very large hail affected northern
parts of Montague County earlier this evening, sensible weather
has quieted down. The boundary layer will continue to stabilize
and we will await the next of several disturbances to arrive
across West-Central Texas and the South Plains early Monday
morning. In addition, another surge of low stratus clouds will
arrive northward and encompass most of the area except the far
western counties. Combined with breezy south-southeast winds 10-15
mph, low temperatures will definitely feel spring-like with low
temperatures remaining well up into the 60s with plentiful
humidity around. Monday will become active by afternoon with a
severe threat from I-35/35W back across our W/NW counties, as the
dryline nudges eastward during prime heating.
05/
&&
.AVIATION... /Issued 713 PM CDT Sun Mar 25 2018/
/00Z TAFs/
Lower MVFR cigs that have persisted much of the day have finally
dissipated the past hour more with multiple level, SCT-BKN VFR
level clouds. Winds continued from the SE around 15 knots, as a
warm front extending from a surface low near KPRS/KSPI across KSPS
and across extreme southern OK near KADM and KDUA. Isolated severe
storms were occurring between KSPS/K0F2. Winds should diminish
closer to 10 knots overnight and convection well to the NW of the
DFW terminals likely will track east across, or just north of the
Red River Valley. Challenges overnight will be mainly stratus and
timing restrictions of cig heights. Thermodynamically, it appears
favorable areas for ISO-SCT TSRA will remain well off on the Bowie
and Bonham cornerpost near the TX/OK border and well west of I-35
with the next approaching shortwave arriving from W TX Mon a.m.
Can`t rule out a few rogue showers near DFW terminals, but Waco
Regional should remain free of convection further south and
underneath the weak shortwave upper ridge. Confidence is too low
beyond 18z for any mention of TSRA/VCTS, with majority of better
focus both surface and aloft just to the NW of the Metroplex and
even more so for Waco.
.DFW Terminals...
RUC and NAM models differ slightly on return of MVFR cigs into the
area, so took a mean of around 07z Sun morning above FL020, lower
below FL020 by 11z, with a TEMPO potential for IFR through 15z
Sun. Cigs should rise back into low VFR between FL030-040 by
21z-22z Sun afternoon. SE winds 10-15 kts through 15z Sun, become
S 15-20 kts with gusts to 25 kts by 18z and after. Moisture below
the inversion aloft will be relative deep and cigs slow to mix.
.Waco Regional
Similar trends on winds and flight restrictions as terminals
across DFW, except MVFR cigs should arrive by 06z Sunday, before
dropping down into IFR by 10z Sun and prevailing. Cigs should rise
to MVFR later Sun morning with VFR returning mid-late afternoon
hours once again, as moisture below the inversion aloft will be
relative deep and cigs slow to mix.
.Monday Night through Wednesday...
The slow-moving upper trough will continue to approach the region
with increasing chances for SHRA/TSRA, with both a severe and
+RA/TSRA threat.
05/
&&
.SHORT TERM... /Issued 249 PM CDT Sun Mar 25 2018/
/Rest of the afternoon through Monday/
Surface analysis this afternoon places a warm front just north of
the Red River, near a Hugo to Ardmore line before it curls southwest
to near Wichita Falls. From here, it meets up with a dryline
which extends southward to just west of a Graham to Cisco line.
Surface convergence appears to be maximized in the vicinity of
this triple point in a region bounded by a Bowie-Burkburnett-Olney
line based on the latest LAPS analysis. Given the lack of more
appreciable large-scale forcing for ascent today (mid-level height
tendencies are either neutral or slightly positive) as the main
upper-low is still just now dropping into the Great Basin, these
mesoscale areas of enhanced convergence will be the only mechanism
to force thunderstorm development today. The farther south along
the dryline you go, the weaker surface convergence becomes, and
thus the lower the prospects for convective initiation.
While 850 mb temperatures are currently running in the 17-19C
range across our western counties, clearing skies have allowed
surface temperatures to jump into the upper 80s/lower 90s across
this part of the region, which is helping to diminish lingering
mixed-layer convective inhibition (MLCINH). While this morning`s
deterministic guidance remained quiet along the dryline, the TTWRF
ensemble seems to have caught on to the increased low-level lift
near the triple point and the reducing in MLCINH, and roughly 75
percent of the 41 ensemble members now convect in this favored
area during the 4-5 PM timeframe. Recent runs of the HRRR are
also indicating a similar convective evolution later this
afternoon.
Recent visible satellite trends also reveal a small area of
increasingly agitated/towering cumulus developing in this
aformentioned zone near the triple point. As a result, it appears
as if a storm (or two) may try to develop here in the next 1-2
hours as surface temperatures continue to warm. Effective deep
layer shear values in excess of 50 kts would certainly support a
supercellular mode, and very large CAPE profiles through the hail
growth zone would indicate a threat for large or very large hail
(golfballs or larger) as any storm tracks initially to the east.
It`s entirely possible that storms move along and just north of
the Red River, but any deviant rightward motion would bring the
threat for severe weather into our northern counties. At this
time, it appears the favored corridor for some a severe threat
exists in a region bounded by a Bowie to Denton to Sherman line.
Storms will likely decay to the east as they encounter increasing
nocturnal inhibition/capping later this evening. The threat for a
tornado, while low, cannot be discounted here given very high low-
level instability which can at times offset otherwise marginal
low-level wind fields (which we have in this instance). Even if a
storm or two develops here, it`s unclear whether convective vigor
will be maintained given the lack of better forcing and increased
capping off to the east, but we`ll continue to monitor this threat
closely over the next few hours.
Late tonight, isentropic ascent will increase across the Concho
Valley. This could result in the development of scattered
showers/storms rooted above the base of the EML plume. With steep
(7.5-8 C/km) lapse rates in place and 35-40 kts of effective
shear, can`t rule out some marginally severe hail in the strongest
storms as they track northeastward. The main corridor for
overnight/early Monday morning activity looks to be north and west
of an Eastland to Sherman line.
Aside from breezy southerly winds tomorrow, most of the day Monday
looks to be relatively quiet on the weather front as low cloud
cover gradually erodes through afternoon. The dryline will mix
back eastward into the Rolling Plains and should reload for
another round of convection by late in the afternoon. A bit more
forcing for ascent will be present on Monday, so storm coverage
will likely be higher than today (Sunday).
Carlaw
&&
.LONG TERM... /Issued 249 PM CDT Sun Mar 25 2018/
/Monday night through Sunday/
Rain and thunderstorm chances will increase Monday night as the
deep upper low rotates through the Desert Southwest and moist
large scale ascent increases. A few severe storms will be possible
across the northwest zones during the evening hours near an
approaching dryline and cold front. Storms should become more
numerous overnight Monday through Tuesday as the cold front
slides into the region. The front will not pack much of a punch as
far as modifying the airmass but will provide an additional
source of lift. Confidence is high that rain and thunderstorms
will be numerous Tuesday but we are less certain of exactly where
the cold front will stall and therefore where the best potential
for strong/severe storms will be. It still appears that the most
likely area will be southeast of a line from Cisco to Sherman, but
again it will all depend on where the front ends up.
Numerous thunderstorms are expected Tuesday night through
Wednesday night as the upper low opens up and translates to the
east. Since ample moisture and lift will both be present, the
potential for heavy rainfall and flooding will increase,
especially across the southeast half of the area. For now we will
hold off on any type of Flood/Flash Flood Watch since the
heaviest rainfall is still a couple of days out and the amount and
exact location are still in question. Best estimates on rainfall
totals still appear to be in the 2 to 3 inch range but higher
amounts are possible in some localized spots.
The main upper trough axis should swing through the region
overnight Wednesday through Thursday which will bring decreasing
rain/storm chances from west to east with precip ending across the
entire forecast area Thursday night.
Zonal flow aloft will set up behind the departing upper trough and
result in relatively quiet weather Friday through Easter Sunday.
A cold front is progged to move into the region Sunday night
through Monday which may result in a few showers and storms.
Mild temperatures are expected through the week with highs
generally in the 70. The only exception will be a slight cool
down Wednesday/Wednesday night behind the cold front.
79
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 67 80 68 72 58 / 10 20 50 80 70
Waco 67 82 67 77 60 / 10 20 30 60 80
Paris 63 78 65 72 55 / 10 30 50 80 80
Denton 66 79 65 71 55 / 20 20 60 80 60
McKinney 66 79 67 71 55 / 10 20 50 80 70
Dallas 68 81 67 73 58 / 10 20 50 80 70
Terrell 66 81 67 75 58 / 10 20 40 70 80
Corsicana 66 82 67 78 60 / 10 20 30 60 80
Temple 66 83 67 78 60 / 10 20 20 50 80
Mineral Wells 66 81 62 70 53 / 20 40 60 70 60
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
05/26
Area Forecast Discussion
National Weather Service Green Bay WI
620 PM CDT Sun Mar 25 2018
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Monday
Issued at 226 PM CDT Sun Mar 25 2018
The latest RAP analysis and satellite/radar imagery show a large
area of high pressure stretching from northern Quebec to the
western Great Lakes early this afternoon. An area of cirrus is
moving across the region, above a very dry airmass with dewpoints
falling to around 5 above over Vilas county. Temperatures have
been slow to warm so far today, with readings mostly in the 30s.
Looking out west, light precip is occurring over the eastern
Dakotas to eastern NE/KS, with a swath of returning moisture. As
the high pressure system departs and a storm system moves towards
the region on Monday, precip chances are the main forecast
concern.
Tonight...The ribbon of moisture return will remain west of the
region over Minnesota and the eastern Dakotas. Meanwhile, high
pressure and associated very dry air will remain present over
north-central and northeast WI. Will see periods of mid and high
clouds pass over north-central WI during the evening. These
clouds should spread east overnight and lower at the same time.
With some clouds and a persistent southeast wind, temps will be
warmer than last night with lows ranging from around 20 over Vilas
county to the upper 20s near Lake Michigan.
Monday...Clouds will continue to increase ahead of a storm system
that will be developing over the northern and central Plains.
Dry air below 700 mb will initially be tough to overcome, so
slowed down precip chances during the afternoon. Most likely
looking at precip chances ramping up after 4 pm over central and
north-central WI. With the incoming cloud cover and east winds,
lowered max temps, especially over east-central WI. Highs should
range from the low to mid 40s for much of the region.
.LONG TERM...Monday Night Through Sunday
Issued at 226 PM CDT Sun Mar 25 2018
Medium range models remain consistent with a widespread one half
inch rainfall Monday night. Expect primarily rain, but cool dry
air mass lingering over northern Wisconsin and far northeast
wisconsin Monday evening may generated a brief mix due to evap
cooling. Added a fog mention later Monday night as winds decrease
with the frontal passage and surface dewpoints climb into the 30s
to lower 40s over at least east central Wisconsin and the
lakeshore region. Trend of the departure of the system with cold
front is a bit quicker Tuesday, with precipitation east of the
area by Tuesday afternoon.
With southwest flow aloft, milder conditions will continue for a
short time from Tuesday into Wednesday.
There is chance of precipitation late Wednesday into Thursday as
a cold front drops through. The air will turn cold enough
Thursday for the precipitation type to be a mix or all light snow.
This cold front will also be the start of trend to below normal
temperatures for the rest of the week and into next weekend.
Timing of pieces of energy carving out the broad cold upper trough
setting up over the northern tier of the country will produce
additional precipitation chances. Timing of these systems is
difficult but current temperature profiles are supporting mainly
snow.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 615 PM CDT Sun Mar 25 2018
Generally good flight conditions are expected for the next 18
hours, though there will be some low-end LLWS overnight. A sharp
downward trend in ceilings will begin tomorrow afternoon and
continue into tomorrow night as precipitation spreads across the
area from the west. More significant LLWS is anticipated at that
time as well.
&&
.HYDROLOGY...
Issued at 226 PM CDT Sun Mar 25 2018
Progs continue to paint around a half inch of rain Monday night
for the forecast area. Latest forecast river guidance with present
qpf forecasts indicate main stem rivers overall remain below
bankfull for this event. Still anticipate some run off issues to
affect small streams and creeks due to snow cover and or lingering
frost in the ground. But this rain should aid with removing some
of the frost in the ground.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......Skowronski
HYDROLOGY......TDH
Area Forecast Discussion
National Weather Service Huntsville AL
919 PM CDT Sun Mar 25 2018
.NEAR TERM...(Tonight)
Issued at 919 PM CDT Sun Mar 25 2018
A rather complex pattern prevailed across the eastern lower-48 this
evening. The main player is a wedge or backdoor cold front moving
southward along the SE coast. This front earlier produced some rather
dramatic temperature falls near the Atlantic coast in the afternoon,
showing that winter`s cold is quite not over with given very chilly
north Atlantic water temperatures. The cold wedge also created a
wider than usual range in high temperatures locally - ranging from
the low/mid 70s in southern Cullman county to only 61 in Ft Payne.
The higher terrain just to the east of Huntsville until recently had
slowed the process of that cold air making it to the Huntsville area.
Although winds in the valley locations were mostly less than 12 mph,
SE winds were gusting to over 20 mph in Monte Sano east of Huntsville
and a thousand feet higher. The cold push from the east will result
in winds becoming easterly, then SE, and increasing into the 10-20
mph range during the overnight.
Further aloft, an approaching upper level system from the west was
producing light showers across parts of MO/AR and the Mid South. A
WNW flow aloft along with increasing upglide in the lower levels will
bring these showers across the Tennessee Valley during the later
evening and overnight. With cold air replacing a more unstable
airmass that was at the surface, only shower and no thunder is
expected. Generally followed an HRRR solution (with adjustments)
regarding the placement and timing of showers tonight.
The low temperatures forecast tonight looked OK, did not make any
changes here. But did increase wind speeds a tad, especially the
gusts in the overnight as the cold air becomes more predominate.
.SHORT TERM...(Monday through Tuesday)
Issued at 221 PM CDT Sun Mar 25 2018
The aforementioned boundary will push back to the east on Monday in
response to an upper-ridge axis building in from the southwest.
Scattered showers will be possible along/near this boundary early
Monday morning -- with the best chances shifting east (with the
boundary) through the day. However, given the fairly dry boundary
layer, QPF amounts will be light as some of the precipitation will
evaporate before reaching the surface. In wake of the front, a stable
air mass will remain in place, with 2-3kft decks of low stratus
persisting throughout the day. Thus, temperatures will struggle to
climb much above the mid to upper 50s. In fact, areas along the AL/GA
may struggle to climb above 50 degrees for the second straight day!
The upper-ridge will continue to build into the region Monday night
into Tuesday, promoting a gradual wind shift to the south and
southwest. The flow will likely help to erode the low-level stratus
decks with time by midday Tuesday, but increase boundary layer
moisture, setting the stage for a prolonged rainfall event late this
week (see long term section below). For Tuesday, think that the lack
of any lifting/forcing mechanism will significantly limit
precipitation chances and have taken out mentionable PoPs in the
forecast. Given the southerly flow and some breaks in the cloud
cover, highs in the mid 60s to around 70 degrees will be possible
(about 10 degrees warmer than Monday).
.LONG TERM...(Tuesday night through Saturday)
Issued at 221 PM CDT Sun Mar 25 2018
A strengthening upper-low pressure system over Texas will gradually
force the upper-ridge to the south and east of the Caribbean. A slow
moving cold front will gradually progress from the Great Plains into
the Mississippi and eventually Tennessee River valleys on Wednesday
through Friday, setting the stage for a prolonged rain event across
the region. Although there are still some model differences on when
the period for heaviest rainfall will occur, all model solutions
hint at a slow/stalled boundary across the region during this time
period. The GFS is a little faster in bringing heavier rainfall in
than the ECMWF and Canadian solutions -- and the ECMWF and Canadian
models keep the heavy rainfall potential in longer on Friday.
Regardless of these differences, confidence is increasing that heavy
rainfall and potential flash/areal flooding threat will exist late
this week, with possible river flooding lingering into the weekend.
Ahead of this front on Tuesday night and Wednesday, deep southwest
flow will continue to advect rich Gulf moisture into the region. This
can be seen in forecast PWATs which jump from around 0.75" (00z
Wednesday) to 1.5" (00z Thursday) at KHSV. A couple of weak
shortwaves rounding the broadening upper-trough will provide enough
lift to generate showers (and even a few thunderstorms) Tuesday night
and especially during the day on Wednesday. Coverage may vary
significantly across the region, with areas west of I-65 (which will
be closer to the boundary) seeing much better chances through midday
Wednesday. However, as the boundary sags into the region Wednesday
night into Thursday, it is progged to stall from the Plateau region
of Middle Tennessee and through Northern Alabama and Central
Mississippi. The boundary will serve as a focus for moderate heavy
showers and thunderstorms from Wednesday night through early Friday
morning.
As one might expect, there are several ingredients that are beginning
to line up for heavy rainfall and flooding during this Wednesday to
Friday period. First, the presence of a boundary with a deep,
moisture fetch off the Gulf of Mexico moving parallel to the
boundary. This would support the generation of deep convection that
would potentially train over the same areas. Secondly, abundant
tropical moisture will be present, with PWATs around 1.5-1.6". These
PWATs would place the area in the 99th percentile for late March. A
deep warm cloud layer was noted on model soundings, with some modest
CAPE that would allow for sustained updrafts and some weakly
organized convection. Thus, we`ll need to watch for a flash/areal
flood threat in the Wednesday night to Thursday night timeframe and
then the possibility for river flooding thereafter should these
projections/trends continue.
Have increased storm total QPF a bit to go along with the latest WPC
thinking. Would not be shocked to see 2 to 4 inches of rain across
the region from 00z Wednesday through 12z Friday (should the boundary
stall over the area), with locally higher amounts possible. This
heaviest band of precipitation will be very dependent on where the
boundary stalls and that`s still uncertain at this time. The front will
gradually move east Friday into Friday night as high pressure builds
in from the northwest. This will result in a cooler, but dry start
to the Easter holiday weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 649 PM CDT Sun Mar 25 2018
A rather strong west to east temp difference continued across the
region, with 6 PM readings around 50 over our eastern areas, to mid
60s over the NW and central areas. A north to south oriented
boundary, or wedge type front located east of Huntsville will
gradually move westward this evening, bringing colder temps and a
wind shift. Along with a temperature fall, lower clouds will produce
MVFR CIGs ~1800 ft AGL at KHSV in the next couple of hours, and CIGs
lowering at KMSL late in the evening. Winds will become east, then SE
tonight, increasing into the 10-15kt range, with gusts above 25kt
possible especially east of I-65. Sustained winds around 35kt 2000 ft
AGL are too low to warrant Low Level Wind Shear this issuance. Have
CIGs improving to VFR Monday afternoon, but staying MVFR at KMSL into
the latter hours of this TAF.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...RSB
SHORT TERM...AMP.24
LONG TERM...AMP.24
AVIATION...RSB
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service Wichita KS
905 PM CDT Sun Mar 25 2018
.UPDATE...
Issued at 904 PM CDT Sun Mar 25 2018
Latest IR satellite (meso 1) images and sfc obs show low clouds and
visibilities beginning to decrease for areas just south of the
Kansas/Oklahoma border. This stratus deck and increasing moisture,
will continue to surge north for the late evening hours,
overspreading most of south central and central KS after midnight.
The further north the moisture gets, the easterly wind component and
upslope flow will enhance the low clouds/and fog potential,
especially for areas west of I-135. SREF model data and bufkit
soundings seem to support this, with a stratus build down type
scenario. Think patchy dense dog will be possible, with visibilities
dropping to 1 to 3 miles, with some locations seeing 1/2 mile
visibilities. So have decided to issue a dense fog advisory for
areas mainly west of a KRSL to KHUT to KICT line, or generally for
areas west of I-135. Will also add some drizzle to the forecast as
well.
As the low level moisture transport increases after midnight, an
elevated unstable airmass will also lift north into south central KS
as well. Latest RAP model shows elevated CAPE values of 1500-2000
J/kg pushing into the area. Isentropic lift also increases, which
suggests that showers and thunderstorms may also develop after
midnight, initially over south central KS, and quickly lift NE, as
the moisture transport lifts NE into NE KS early on Mon morning.
Some uncertainty on how many storms will be possible over south
central KS, as bufkit lapse rates above the saturated low layers
aren`t too steep. Think areas NE of KICT will see the most storms,
with a few strong to possibly severe storms during the early morning
hours on Mon, given the above mentioned instability and bulk shear
of 50-60 kts.
Ketcham
&&
.SHORT TERM...(This evening Tuesday)
Issued at 327 PM CDT Sun Mar 25 2018
Precipitation chances/coverage and temperatures are the biggest
challenges of the forecast for the first part of the week. The
latest resolutions for precipitation show development not really
until after midnight. Adjustments have been made to this field in
order to account for the latest guidance. Instability does
increase this evening into the overnight hours. Thus it is still
possible there could be a couple of strong to severe storms. The
Storm Prediction Center has expanded their marginal risk to
encompass the entire forecast area. This threat would be for
primarily hail in the overnight hours.
While there is an inflow of warm air advection, the question is how
will the cloud cover and precipitation impact the temperatures. A
tight gradient is possible with the models differing in their
resolutions for high temperatures. The swing is about 20 degrees
between the GFS and NAM across central Kansas. It seems that the
cooler solution has been on the winning side of this match up. Thus
this was the choice for that area. South central Kansas appears to
stay in the warm sector. Breaks in the clouds could be seen to aid
the daytime heating. There is definitely the potential for a bust in
either direction.
Showers and thunderstorms remain possible throughout the day on
Monday. There is the potential for an isolated strong to severe
thunderstorm in the afternoon and evening. As mentioned in the
previous discussion, the daytime heating factor will play into
stability of the atmosphere.
.LONG TERM...(Tuesday Night through Sunday)
Issued at 327 PM CDT Sun Mar 25 2018
Medium range models are in relative agreement that, during the
middle of the week, a moderate PV anomaly moves into the western
and central US. This system will bring additional moisture and
precipitation to the region.
The main challenge with this system is the uncertainty with the
location of the front. Quite confident that precipitation will
occur. The location of the front will drive the threat of severe
weather. Currently, only the extreme portion of southeast Kansas
may expect any severe weather, and that chance is small at best.
On the tail end of the system as it passes is another disturbance
that could bring additional precipitation Thursday. Some of this
may be snow in central Kansas based on forecast soundings and cool
surface temperatures Thursday night and into early Friday.
A third disturbance will begin having influence over the region
over the weekend and early next week. Strong southerly flow
Saturday ahead of a developing over the High Plain may bring a few
showers in the are of isentropic ascent across Kansas. Storms
chances increase in earnest Sunday and Monday as the front moves
through. Behind the front, some of the precipitation may change to
snow, mainly across central Kansas.
Overall, the pattern is increasing in activity. With that,
temperatures are expected to be mainly below normal which will
suppress severe weather chances.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 658 PM CDT Sun Mar 25 2018
Easterly surface flow will lead to lots of upslope flow for the
overnight hours, especially for areas east of the I-135. Increasing
low level moisture transport, in combination with this upslope flow,
will lead to deteriorating aviation conditions late this evening and
overnight, especially for areas west of I-135 where terrain
influences will be enhanced. This will lead to Cigs for most of the
south central and central KS TAFS dropping to IFR/LIFR. The
moisture transport and increasing elevated instability will also
lead to increasing chances of SHRA/TSRA across most of the region
after 06z/Mon. So will go with VCTS for most locations from 06-10z
and go with tempo groups for TSRA. Could also see some MVFR vsbys in
and around the stronger storms.
Ketcham
&&
.FIRE WEATHER...
Issued at 327 PM CDT Sun Mar 25 2018
Pattern becoming more active for precipitation over the next
week. No strong winds really to speak of until next weekend ahead
of the next system. Even then, the GFDI only gets into the
moderate category.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 51 67 44 52 / 60 40 30 30
Hutchinson 48 60 41 52 / 60 40 20 20
Newton 48 62 42 51 / 60 50 30 30
ElDorado 49 66 44 52 / 60 50 40 40
Winfield-KWLD 52 71 47 53 / 60 40 50 50
Russell 45 49 37 55 / 50 30 10 10
Great Bend 46 51 38 53 / 50 30 10 10
Salina 47 52 40 54 / 70 50 20 20
McPherson 47 56 40 52 / 60 50 20 20
Coffeyville 53 67 52 56 / 80 60 80 70
Chanute 49 65 48 52 / 70 70 70 70
Iola 47 64 47 51 / 70 70 70 60
Parsons-KPPF 51 66 51 55 / 80 60 80 70
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM CDT Monday for KSZ032-047-050-067-
082-083-091-092.
&&
$$
UPDATE...Ketcham
SHORT TERM...VJP
LONG TERM...KRC
AVIATION...Ketcham
FIRE WEATHER...KRC
Area Forecast Discussion
National Weather Service Jacksonville FL
805 PM EDT Sun Mar 25 2018
...Locally Heavy Rainfall I-10 Corridor Northward This Evening...
...Breezy and Cooler with Rough Surf Conditions...
.UPDATE...Backdoor cold front bringing much cooler and windy
conditions is now pushing sw across ne Fl this evening. Training
showers are producing heavy downpours and will continue this
evening along and behind front with help of upper impulse in nw
flow aloft. Rainfall amounts of one half to one inch may occur
near the I-10 corridor. Isolated thunder occurred earlier with
daytime heating but lightning activity has now decreased as
instability fades. Expect shower activity to decrease after
midnight as HRRR model indicates.
&&
.AVIATION...IFR conditions will persist tonight through Monday as
low clouds and showers behind backdoor cold front linger over the
area. NE winds will be around 15 knots with gusts up to 25 knots
near the east coast.
&&
.MARINE...Surge of ne winds and building seas have spread south
across the waters this afternoon and evening in wake of backdoor
cold front. Occasional gusts to Gale force may occur over the
waters through Monday. Advisory conditions will continue into
midweek as strong high pressure builds south and swells persist.
Rip Currents: High risk expected through Monday and Tuesday due to
strong onshore winds and rough surf.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 49 58 53 70 / 30 10 10 10
SSI 51 57 56 66 / 30 20 20 10
JAX 55 62 58 72 / 80 20 20 0
SGJ 58 65 62 71 / 80 30 20 0
GNV 56 67 59 78 / 50 10 10 0
OCF 57 72 60 79 / 30 10 10 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...Small Craft Advisory until 10 PM EDT Wednesday for Waters from
Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-
Waters from Fernandina Beach to St. Augustine FL from 20 to
60 NM-Waters from St. Augustine to Flagler Beach FL from 20
to 60 NM.
Small Craft Advisory until 10 AM EDT Tuesday for Coastal waters
from Altamaha Sound to Fernandina Beach FL out 20 NM-
Coastal waters from Fernandina Beach to St. Augustine FL
out 20 NM-Coastal waters from St. Augustine to Flagler
Beach FL out 20 NM.
&&
$$
Zibura/Sandrik/Shashy
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1025 PM EDT Sun Mar 25 2018
.UPDATE...
Issued at 1025 PM EDT SUN MAR 25 2018
Forecast soundings show a very shallow layer of elevated
convection for the western portion of the forecast area tonight
into Monday. However, models also showed light precip should
already be to our southwest over TN this evening, but it has not
materialized yet. In light of reality to this point, have trimmed
back the POP to no more than 10%, but held on to the possibility
of sprinkles over the western fringe of the forecast area late
tonight into Monday morning.
UPDATE Issued at 854 PM EDT SUN MAR 25 2018
Valley temps are dropping off quickly in the northeast part of the
forecast area where snowcover looks like it survived through the
day. However, clouds are also moving in from the southwest. Have
made temperatures adjustments for colder readings in the northeast
valleys this evening, but allowed for ridge/valley equalization
overnight under what should become overcast conditions.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 320 PM EDT SUN MAR 25 2018
18z sfc analysis shows an inverted trough of low pressure to the
south with high pressure over the northern parts of the Ohio
Valley. The gradient between these two features is making for east
to northeast flow of winds - around 10 mph with occasional gust
to 20 mph - that are slightly downsloping across the area. As a
result, most of eastern Kentucky enjoyed sunny conditions today -
aside from the high clouds over southwest parts of the Cumberland
Valley. This has helped to clear out some of the snow from
yesterday in the north, but temperatures were hindered there due
to the melting there. Subsequently readings ranged from the lower
40s north to the mid/upper 50s south with dewpoints likewise
varying from the low/mid 20s north to the lower 40s south.
The models are in good agreement aloft through the short term
portion of the forecast as they all depict a dirty ridge passing
over the Ohio Valley with dampening energy riding through
Kentucky tonight and during the day Monday. This is in the wake
of the deep trough pulling away well to the east this evening
taking the stronger shortwave impulses along with it. For Monday
night the ridge axis will move through eastern Kentucky allowing
southwest flow to start to bring more mid level energy into the
state, just to our west, through the night and into Tuesday
morning. Given the good model agreement have favored a general
blend with lean on the higher resolution NAM12 and HRRR in the
near term for details.
Sensible weather will feature moisture returning back into eastern
Kentucky from the southwest. This will bring in an increase in
cloud cover tonight from southwest to northeast with even some
sprinkles or a light rain shower possible. To the north, skies
will remain clear enough over the remaining snow cover to drive
temperatures toward freezing before the area is overrun by the
thickening clouds. Pockets of sprinkles or a stray light rain
shower will be possible in the west on Monday beneath the thick
cloud deck. By evening, a warm front will be lifting through
Eastern Kentucky with a better chance of rain showers for the
area as it tracks northeast that night. The clouds tonight and
Monday night should keep much of any fog (or frost) at bay through
the period despite the ample boundary layer moisture.
Used the CONSShort and ShortBlend as a starting point for all the
grids with only minor adjustments to temperatures - aside from
lowering the snow cover areas tonight. As for PoPs tried to reign
in the sprinkles and light showers tonight and Monday - keeping
them mainly in the western parts of the CWA closer to the low
pressure and developing warm front.
.LONG TERM...(Tuesday through Sunday)
Issued at 431 PM EDT SUN MAR 25 2018
The models remain in general agreement with an amplified split-
flow pattern to rule across the CONUS through the end of the work
week, before phasing and then transitioning to a more zonal flow
pattern into the weekend. Ridging will get shoved to the Eastern
Seaboard by mid-week, as a broad trough gradually moves across the
Mississippi Valley. This will allow for a northeast to southwest
oriented baroclinic zone to take shape from the Ohio Valley down
to the Arklatex region. This boundary will then slowly move
southeast, yielding another extended period of unsettled weather
across our area.
A warm front will be lifting northeast across the area Tuesday
morning, bringing the threat of showers through at least the first
half of the day. The surface cold front will then move in from
the northwest Tuesday night into Wednesday, bringing more
widespread showers to the area. This boundary will get hung up in
the vicinity of the region, with another surge of moisture and
lift occurring Thursday into Friday. There still remains
disagreement on the evolution of smaller scale features during
this time frame, with the ECMWF remaining slower, while the GFS
stays progressive. Either way, will continue to monitor QPF
trends, as multiple rounds will allow for a threat of excessive
runoff eventually for some locations. Generally drier weather can
be expected through most of the weekend, with another front
approaching from the northwest by late Sunday. Temperatures will
average near to slightly above normal through Friday, before
cooling down slightly into the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 737 PM EDT SUN MAR 25 2018
VFR ceilings mostly in the 3500` to 5000` range are currently
affecting the southwest portion of the forecast area around KEKQ,
K1A6, KSME, and KLOZ. Those ceilings will spread northeast over
the rest of the forecast area by around 06Z, and generally persist
through the remainder of the forecast period. Ceilings could dip
to MVFR levels tonight around KEKQ. Winds will be from the
northeast to east this evening, and become southeasterly
overnight. Speeds through the period will generally be less than
10 kts.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL
SHORT TERM...GREIF
LONG TERM...GEOGERIAN
AVIATION...HAL
Area Forecast Discussion
National Weather Service Louisville KY
812 PM EDT Sun Mar 25 2018
.Forecast Update...
Issued at 810 PM EDT Sun Mar 25 2018
Inverted surface trough was draped SW to NE through Middle Tennessee
this evening. Looking at the 925-700 mb layer, a subtle wave over
the OH/TN valleys is resulting in isentropic lift and mid-level
clouds. Low clouds were still confined near and south of the TN
border, closer to the low-level trough. This weak boundary slides
north overnight. With weak lift, latest HRRR runs have featured
sprinkles moving south to north through the area through sunrise.
Other than some sprinkles Monday morning, the first half of the day
looks largely dry. So only forecast change this evening was to delay
precip chances until early to mid-afternoon. A warm advection band
of precip is likely to move into the western CWA after 20z Monday.
&&
.Short Term...(This evening through Monday night)
Issued at 257 PM EDT Sun Mar 25 2018
Skies this afternoon range from partly cloudy across southern IN and
north central KY to mostly cloudy over south central KY.
Temperatures range from the mid to upper 40s. A few radar returns
showing up across south central KY are likely resulting in some
sprinkles.
For tonight, and inverted surface trough currently across east
central KY will shift back to the west tonight and end up over
central KY. Convergence along this trough will result in sprinkles
and isolated showers across the region overnight. Clouds and winds
shifting to southeasterly will limit the temperature fall. Lows will
bottom out in the mid 30s to lower 40s.
On Monday a warm front will approach and move north across the
region. Scattered to numerous showers will accompany this front as
it moves through Monday afternoon into the overnight hours. Highs on
Monday will be in the mid to upper 50s. Lows Monday night will drop
only into the mid to upper 40s.
.Long Term...(Tuesday through Sunday)
Issued at 310 PM EDT Sun Mar 25 2018
The long term period will start out warmer as much of the lower Ohio
Valley will reside in the warm sector of an approaching system.
Showers and potentially a few thunderstorms will be possible,
particularly over southern IN. Rain chances will fall off the
farther south and east you go in central KY Tuesday. Highs will top
out in the 60s.
The best chance for widespread rain will be Tuesday night into
Wednesday as the cold front associated with the system mentioned
above slowly moves through. Precipitable water values near 1.5" will
result in moderate to possibly some heavy rainfall.
Precipitation chances will decrease on Wednesday night, but an upper
level wave will approach towards the morning hours Thursday. This
will try to phase with the stalled frontal boundary to the east and
bring another round of potentially soaking rain Thursday into
Thursday night. This rain may last into Friday as well and end as a
bit of a wintry mix. However, models are very inconsistent on this
solution, so confidence in the amount of precipitation for Friday is
low. Overall, area wide 1-2.5 inch rainfall amounts with some higher
values can be expected next week. This may lead to some rises on the
smaller area rivers and potentially some minor flooding.
&&
.Aviation...(00Z TAF Issuance)
Issued at 740 PM EDT Sun Mar 25 2018
A few sprinkles or very light rain showers can be expected tonight
into tomorrow morning under very weak isentropic lift near a
boundary to our south. Flight conditions will drop from VFR to MVFR
tonight at BWG and tomorrow morning at HNB/SDF/LEX as better low
level moisture pushes in from the south. Expect a breezy day
tomorrow with southeast sfc winds of 10-14 kts with gusts to around
17-20 kts. A return to VFR is possible from late morning through
early afternoon before better rain shower chances and MVFR
conditions move in for late afternoon into the evening hours.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...EBW
Short Term...EER
Long Term...EER
Aviation...AMS
Area Forecast Discussion
National Weather Service Mobile AL
641 PM CDT Sun Mar 25 2018
.DISCUSSION...Updated for latest aviation discussion below.
&&
.AVIATION...
26/00Z issuance...VFR conditions will continue through late this
evening, but low clouds and fog develop and become more widespread
across the region by around 26/06z. IFR ceilings and surface
visibility expected across parts of the region overnight. The IFR
ceilings will then likely persist through most of the day on
Monday, and while surface visibility remains somewhat limited
through the day due to patches of light advective sea fog,
visibility should be no lower than MVFR. Light southeasterly flow
continues, moderate at times Monday afternoon, especially near the
coast. 12/DS
&&
.PREV DISCUSSION... /issued 402 PM CDT Sun Mar 25 2018/
NEAR TERM /Now Through Monday/...Taking a look at the current
situation over the area, am seeing a few radar returns over
northeastern parts of the forecast area. Am also seeing the coming
backdoor front northeast of Maxwell radar. This front is being
pushed across the Southeast by an upper system wobbling around off
the New England Coast, and at this point is fighting a general
westerly low level flow due to surface high over the central Gulf
of Mexico. A cap on the latest LAPS analysis and RAP
initialization situated around 700mb has been helping to limit
development attm, though.
Ahead of the front tonight, have left in showers mainly over the
northern half of the area, with the current activity expected to
last into the evening. How far south/southwest the showers/storms
spread depends on how strong the cap remains. At this point, with
southern parts of the forecast area seeing the least amount of
heating today, this portion has the least amount of instability.
As the front moves over the forecast area late tonight through
Monday, am expecting showers to move southwest/west across the
forecast area, with any residual showers along the western border
or west of the area. With instability still in place on the model
soundings, feel any thunder mixing in will be very limited after
midnight. With a moist atmosphere in place, put in light fog ahead
of the front, over the southwestern half of the forecast area.
Now for the challenging part of the forecast, temperatures. With
significantly cooler air moving over the forecast area behind the
front, a significant southwest to northeast temp gradient
results. For tonight, the gradient isn`t as pronounced, with lows
ranging from low 50s northeast to low 60s southwest and along the
coast. For Monday, as the colder air overspreads the forecast
area, a 13 degree spread in highs is expected, ranging from well
below seasonal northeast to around seasonal southwest. /16
SHORT TERM /Monday night Through Wednesday night/...Will start
off this period with a short-wave upper ridge positioned from the
Gulf, northward up across the Appalachians while a positive tilt
upper level trof digs into the four corners of the Desert southwest.
This pattern mostly holds thru Tuesday. At the surface, a large
pressure ridge expands over the southeast US. The larger scale
subsidence, with the upper ridge in place, keeps the chances of
precipitation low (10 to 20%) Monday night thru Tuesday night.
Moving into Wednesday, the ridge aloft slips more eastward with
the local area coming under more of a southwest flow aloft. In
this flow pattern, the passage of a series of impulses, when
interacting with deep moisture and daily instability favors
potentially more of a chance of showers and perhaps a few storms
over the far western zones, to a slight chance closer to the I-65
corridor Wednesday. Patchy night-time fog possible Monday night
and Tuesday night. Temperatures gradually moderating. /10
LONG TERM /Thursday Through Sunday/...Cold front is forecast to
approach from the west and make passage by Thursday night.
Global spectral solutions on the timing of the front diverge more
greatly going into Thursday night with the 25.12Z GFS more
progressive/fast than the ECMWF. Despite the uncertainty, both
solutions continues to support higher pops for the area as the
front approaches and moves through. Will have likely to
categorical pops for Thursday along and west of I-65 with good
chance pops further to the east.
For Thursday night, will have likely pops for the entire area.
For Friday, will have slight chance to chance pops for roughly the
eastern half of the area for lingering precipitation in the wake
of the front, then dry conditions follow. A slight chance of
showers return by Sunday. /29
Confidence on strong to severe storms for Thursday is
low at this time, also given the uncertainties given different
outcomes on progression of best instability and jet streaks in the
longer range guidance. /10
MARINE...A front will cross the area later tonight through Monday
from the northeast, switching the light, general southwest to
westerly flow to strong easterly. As the post-frontal surface
winds shift southeast along the coast, the winds over area
coastal waters will shift to southerly by Thursday. A front is
expected to cross the coastal waters Thursday night into Friday.
Timing has been inconsistent with this fropa, with a slow shift to
later periods in the week, so have less confidence with timing at
this point. /16
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk through Monday morning for ALZ265-266.
FL...High Rip Current Risk through Monday morning for FLZ202-204-206.
MS...None.
GM...Small Craft Advisory from 7 PM Monday to 1 PM CDT Tuesday for
GMZ630>636.
Small Craft Advisory from 7 AM Monday to 9 AM CDT Wednesday for
GMZ650-655-670-675.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Nashville TN
814 PM CDT Sun Mar 25 2018
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Latest radar imagery and surface observations indicate light
showers and drizzle that were affecting much of Middle Tennessee
have ended for now. However, latest HRRR indicates showers along
the TN/AR border will spread eastward into our southwest counties
later this evening and overnight, where chance pops are already in
place. Cannot rule out a few showers or drizzle across the rest of
the area overnight as well due to the very moist low levels
trapped beneath the extreme low level temperature inversion around
3000 ft shown on the 00Z OHX sounding. Forecast is generally on
track and just made minor tweaks based on latest obs and HRRR runs.
&&
.AVIATION...
00Z TAF DISCUSSION.
Winds have shifted from northerly to southerly at CSV. Expect all
taf sites to follow suit as the evening progresses. Cigs should
remain within MVFR and IFR range overnight tonight with
visibilities remaining mainly VFR. There is the chance that some
light showers may form and move north through Middle Tennessee
later tonight. They should be isolated, so haven`t included them
in this issuance. The better chance of showers will be Monday
afternoon as a system moves from west to east across the area.
Have left vcsh in the forecast for CKV, and will likely add it to
the other sites with the next forecast.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......Shamburger
AVIATION........11
Area Forecast Discussion
National Weather Service San Angelo TX
643 PM CDT Sun Mar 25 2018
.AVIATION...
/00Z TAFS/
IFR to MVFR stratuS returns over most terminals from southeast to
northwest overnight, then rising/scattering out to VFR towards or
just after noon. KABI is the exception, with stratus staying just
south and east. An isolated shower or thunderstorms is possible
tonight and Monday morning, but potential will be increasing after
21Z Monday, and especially towards 00Z Tuesday. Added VCTS at
KABI and KSJT 21Z Monday.
&&
.PREV DISCUSSION... /issued 248 PM CDT Sun Mar 25 2018/
SHORT TERM...
(Tonight and Monday)
The forecast is somewhat problematic with rain chances tonight and
Monday. Our area will be under fairly strong southwest flow aloft,
as an upper trough deepens into the southwestern part of the country
on Monday. The dryline has mixed farther east this afternoon across
the northern part of our area, and less across the south. At San
Angelo (west of this dryline), the temperature has reached 93
degrees so far this afternoon, tying the record high for this date
(set in 2011). Anticipate that with additional heating, this this
record will be broken.
By late afternoon, expect the dryline to extend from near
Throckmorton to Coleman to just west of Sonora. Despite MLCAPE
values of 1500-2500 J/kg just head of the dryline, not anticipating
thunderstorm development along it given the cap strength and fairly
weak convergence. The dryline will retreat to the west across west
central Texas this evening and early tonight. Development of a weak
low-level jet will aid in low-level moisture transport across our
area tonight. The models vary considerably tonight and Monday with
rain chances, with the 12Z NAM much drier than the GFS. The HRRR has
been dry for this evening and tonight in our area, while the 12Z TTU
WRF indicates scattered convective development late tonight into
Monday morning across the Big Country area along and north of I-20.
While not readily apparent on satellite imagery, if an embedded
disturbance in the aforementioned southwest flow aloft enters our
area, the chance for shower/thunderstorm development would be
increased. The mid-level lapse rates for tonight and forecast
instability on Monday, combined with favorable vertical shear, are
supportive of strong to severe thunderstorms should development
occur. At this time, we are keeping PoPs on the low side (20-30
percent). Looks like the better chance will be toward Monday
evening, with the dryline expected to be just west of our area.
Temperatures will remain well-above normal tonight and Monday. Lows
tonight are expected to be mostly in the mid 60s, with highs on
Monday in the lower to mid 80s.
LONG TERM...
(Monday Night through Sunday)
No significant changes to the forecast, with showers and
thunderstorms looking likely starting Monday Night and continuing
for portions of the area into Wednesday. Scenario hasn`t changed
much, with storms along the dryline across the far western Concho
Valley early Monday evening blossoming on Monday Night across much
of the area. This area of convection shifts into the eastern
counties for Tuesday. Although the air mass behind the first round
of storms will be less unstable and there may be a break in the
precipitation for awhile, there is something to work with when
the stronger cold front arrives late Tuesday Night and into the
day on Wednesday. Thus, rain chances will continue for Wednesday
and Wednesday Night. Upper level trough axis shifts across the
area early Thursday and takes the precipitation chances with it as
it exits.
Cooler temperatures on Tuesday with lots of clouds and a rain
cooled air mass across the area. Highs in the 70s. Even cooler
behind the front on Thursday with highs in the 60s.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 65 83 60 71 / 20 30 70 50
San Angelo 64 84 61 76 / 20 30 60 40
Junction 64 84 64 77 / 20 20 50 60
Brownwood 65 81 62 73 / 20 20 60 60
Sweetwater 65 82 58 71 / 20 30 50 20
Ozona 64 82 61 76 / 20 20 60 40
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
99/99/04