Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/08/18
Area Forecast Discussion
National Weather Service Charleston SC
945 PM EST Wed Mar 7 2018
.SYNOPSIS...
High pressure will build in from the west through Saturday. A
low pressure system may affect the region Sunday and Sunday
night. High pressure will return early next week with cooler
and dry conditions.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Tonight: Our forecast is on track with building high pressure
and low level cold air advection throughout the night. Around
sunrise, we expect mid 30s to be common over inland areas and
the main question is coverage of frost given some spread in the
surface temps and dew points. There appears to be enough of a
chance for sheltered locations to see scattered frost to hoist
an advisory, especially since latest hourly RAP13 and HRRR progs
appear to be running a bit colder than say 2-3 hours ago. Skies
will remain clear overnight with cirrus brushing coastal zones.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
A strong upper low over the Great Lakes will move eastward off the
New England coast by Friday. The region will remain on the southern
periphery of this upper trough, as strong, cold high pressure at the
surface builds across the region from the west. No precipitation is
expected through the period.
Temperatures will be below normal through Friday, then moderate to
near or slightly above normal by Saturday. Highs on Thursday will be
in the mid to upper 50s, around 60 to the lower 60s on Friday, then
around 70 to the lower 70s Saturday. Low temperatures will be quite
cold Friday morning. Still going with pockets of freezing/near
freezing temperatures well inland. May need to raise a freeze watch
for a portion of the interior for Thursday night. Slightly warmer
minimum temperatures Friday night, with upper 30s to around 40
expected. There could be patchy frost well interior Friday night,
but confidence not high enough to put in forecast at this time.
Winds will remain westerly Thursday and Friday, and are expected to
be a tad on the breezy side again for Thursday afternoon. By
Saturday, low level winds veer to southwest as a low pressure system
takes shape over the central U.S. and the surface ridge pushes
offshore to the east.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
A series of upper shortwaves will bring a surface low pressure
system through the area Saturday night through Sunday night,
with increasing chances for rain. A large area of Canadian high
pressure builds southeast under a longwave trough early next
week, likely resulting in a period of below normal temperatures
and dry weather.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
VFR. Gusty WNW flow expected Thursday afternoon as the mixed
layer deepens.
Extended Aviation Outlook: Saturday night and Sunday: Flight restrictions
will be possible as a low pressure system potentially moves across
or just north of the region. There is still considerable model
uncertainty with the strength and location of this storm system.
Given the model uncertainty, it is possible that periodic
flight restrictions linger into Monday.
&&
.MARINE...
Tonight: A fairly tight pressure gradient will persist over all
coastal waters as high pressure prevails over the region. Cold
air advection over the waters tonight will help maintain Small
Craft Advisory level conditions in offshore Georgia waters. In
general, offshore flow near 15 kt over near-shore waters will
gust to 20 kt occasionally with seas 2 to 3 ft seas with waves
running higher over waters beyond 20 NM.
Brisk northwest winds will start the period with strong high
pressure building from the west. Small craft conditions will
continue over the offshore GA waters through early Friday afternoon.
Elsewhere, winds generally 15-20 knots from the west-northwest
through Friday night, with the strongest winds mainly during the day
time periods. By Saturday, high pressure pushes offshore as another
low pressure system forms over the central U.S.. This will cause
winds to veer to southwest and increase Saturday night through
Sunday. Small craft conditions will be possible by Saturday across
most/all of the marine area. However, there is still decent model
uncertainty with the strength and position of this low pressure
system later this weekend and into early next week.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Frost Advisory from 4 AM to 9 AM EST Thursday for GAZ087-088-
099>101-114>116-137-138.
SC...Frost Advisory from 4 AM to 9 AM EST Thursday for SCZ040-
042>045-047.
MARINE...Small Craft Advisory until 1 PM EST Friday for AMZ374.
&&
$$
NEAR TERM...
SHORT TERM...
LONG TERM...JRL
AVIATION...
MARINE...
FIRE WEATHER...
Area Forecast Discussion
National Weather Service Quad Cities IA IL
535 PM CST Wed Mar 7 2018
...00Z AVIATION UPDATE...
.SYNOPSIS...
Issued at 253 PM CST Wed Mar 7 2018
18Z surface data has high pressure over the Plains with a storm
system. Dew points were in the teens from the upper Great Lakes into
the northern and central Plains. Dew points in the 20s ran from the
Ohio Valley into the lower Mississippi Valley and southern Plains.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 253 PM CST Wed Mar 7 2018
Late this afternoon and evening
Assessment...medium confidence
An upper level disturbance has been producing a persistent band of
light snow across central Iowa. Rap trends show the forcing from
this disturbance slowly moving into the far southwest/south late
this afternoon and evening before dissipating. As a result, pops
have been added to the far southwest/south areas.
With the setting sun, this band may be capable of producing a
dusting of accumulation on grassy surfaces.
Across the remainder of the area, there are questions regarding the
potential for flurries late this afternoon/evening. If flurries
occur, they would be isolated in nature and last no more than an
hour or two.
Late tonight into Thursday
Assessment...medium to high confidence
Quiet and dry conditions should be seen across the area as high
pressure begins building into the Midwest. Temperatures should
average slightly below normal.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 253 PM CST Wed Mar 7 2018
Generally dry into the middle of next week with a potential system
late in the weekend.
Thursday night through Saturday
Assessment...high confidence
Quiet and dry conditions will be seen as high pressure moves through
the Midwest. Temperatures will average below normal. Model trends
are now indicating that the daylight hours of Saturday have a higher
probability of being dry.
Saturday night on...
There are still questions regarding the second event late this
weekend. Run-to-run continuity of the models continues to remain
poor and this will probably continue for at least another 24 hours.
Saturday night through Sunday night
Assessment...low confidence
The model consensus has slight chance to chance pops Saturday night
through Sunday night. The low confidence is based on where the
second system will track.
The ECMWF suggests the area getting side-swiped by the system with a
light rain/snow event. The CMC global has two separate pieces of
energy associated with the system. The first moves across the entire
area with light snow. The second piece of energy side-swipes the
western half of the area with a rain/snow event. The GFS has a
strong system going up the Ohio Valley that misses the area.
However, the GFS also has a weak disturbance that moves across the
area bringing a rain/snow event.
Monday through Wednesday
Assessment...medium confidence Monday then high confidence
The model consensus has quiet and dry conditions as high pressure
slowly moves through the Midwest. The medium confidence for Monday
is for a weak upper level disturbance that moves through the western
Great Lakes that could generate flurries east of the Mississippi.
Temperatures are expected to average near normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 534 PM CST Wed Mar 7 2018
A weak upper level system will spread flurries and possibly a
period of MVFR ceilings into the BRL area this evening, while the
rest of the terminals will see mostly clear skies by midnight.
Although a tempo group for MVFR conditions has been included at
BRL, forecast confidence is below average on trends there this
evening. Overnight into Thursday, high pressure moving into the
region will provide mostly clear skies and lighter northwest
winds at all sites.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...08
AVIATION...Sheets
Area Forecast Discussion
National Weather Service Marquette MI
659 PM EST Wed Mar 7 2018
.SHORT TERM...(This evening through Thursday)
Issued at 245 PM EST WED MAR 7 2018
Latest water vapor imagery and RAP analysis shows a closed low over
northern Lake Mi. Models indicate this low which provided
enhancement to lake effect snow last night is expected to slide se
tonight and reach the Lower Great Lakes by Thu morning. Loss of
synoptic forcing from departing low along with 850mb temperatures
modifying from around -13C this afternoon to -10C to -12C late
tonight into Thu should lead to a diminishment of nnw flow lake
effect snow late today into Thu. Did end up having to reissue a
winter weather advisory for Alger through 21Z as some lingering weak
forcing from low to south was still enhancing some lake effect snow
in vicinity of Munising.
Any lingering nnw flow les should diminish substantially Thu
afternoon with increasing subsidence as inversions continue to lower
blo 3kft. Expect 12-hour snow amounts of 1-2 inches tonight and only
an inch or less on Thu.
.LONG TERM...(Thursday night through Wednesday)
Issued at 303 PM EST WED MAR 7 2018
Really no significantly impactful weather expected in the long term.
Light lake effect Wed night gradually diminishes through the end of
the week, with only some flurries expected by Sat due to a ridge
passing through. Could see some synoptic or lake enhanced snow later
in the weekend and early next week as models show a couple
shortwaves moving through, but models greatly disagree with details.
Blended initialization performed well, so no changes were needed
this shift.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 656 PM EST WED MAR 7 2018
MVFR conditions with lake effectd snow/clouds will linger into
Thursday at KCMX and KSAW with possible improvement to VFR by mid
to late afternoon. With slightly drier air farther to the west,
cigs just above MVFR are expected at KIWD that may drop again into
the MVFR range late tonight.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 245 PM EST WED MAR 7 2018
Winds should remain 25 knots or less through this forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...Titus
AVIATION...JLB
MARINE...Voss
Area Forecast Discussion
National Weather Service Charleston WV
916 PM EST Wed Mar 7 2018
.SYNOPSIS...
Upslope flow will result in snow, mainly in the northern
mountains, tonight into Friday. Another low pressure area with
a chance of snow and rain showers this weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 915 PM Wednesday...
Opted to let go of the winter weather advisory for the northern
mountains. Only isolated to scattered snow showers are expected
tonight with little to no snow accumulation.
As of 645 PM Wednesday...
Made some adjustments to POPs on Thursday. As higher resolution
models are getting into the Thursday time period, it looks like
another decent day for some snow squalls. RAP and NAM snow
squall parameters are showing a good signal for an area or line
of snow squalls moving from the Tri-state into the southern and
central mountains from late morning into the afternoon. So have
bumped POPs up to around 50 percent. Would have gone higher,
however with the RAP and HRRR just getting into this time frame
did not want to make a really drastic jump on just a couple
model runs. Would not be surprised to get some rumbles of
thunder in the squalls as well...like we saw today across the
Middle Ohio River Valley into northcentral WV. Also like today,
temperatures should be in the mid 30s during these squalls so
not much in the way of accumulation is expected across the
lowlands, however brief drops in visibility could impact travel.
As of 108 PM Wednesday...
Upper level shortwave and associated precipitation will
continue to push east of the region this evening with west to
northwest upslope flow expected to develop across the region.
As the shortwave moves away, expect precipitation to become
confined to the mountains tonight. Cold temperatures, sufficient
low-level moisture and upslope flow should result in accumulating
snow in our northern and central mountains with the greatest
accumulations being in the favored northwest facing slopes of
the northern mountains.
A weak shortwave is forecast to push east by late tonight with
another stronger wave expected tomorrow. These features are
expected to result in a few scattered rain/snow showers even
across some of the lowland counties. Could still see some
accumulating snow across the higher elevations of the mountains
on Thursday. However, amounts should be lighter than tonight and
because of this, not planning on extending the winter weather
advisory.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 235 PM Wednesday...
Models showing a lobe of the upper level low rotating over
northern/northeastern portions of the forecast area for Thursday
night into Friday. Actually get some warming which will inhibit
some of the auto convective/upslope flow despite a
northwesterly wind, so system will have to rely more on upper
level dynamics.
A clipper then pushes moisture into southern portions of the
forecast area for Friday night into Saturday. Could see a decent
band of snow with this system, but there are considerable placement
differences between models.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 240 PM Wednesday...
Still a wide variety of solutions with the system for Sunday
into Monday. GFS continues to be the furtherest north and
strongest with the system while the Canadian and ECMWF have trended
north, but still keep the bulk of the system south of the area.
Will use a compromise solution while keeping a close eye on the
situation.
Expect a northwest upslope flow behind the system with enough
moisture for some mountain snow on Tuesday into Wednesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As of 645 PM Wednesday...
Convectively driven snow showers should be on the decrease this
evening, with just lingering upslope snow showers across the
northern mountains. Expect another round of snow showers on
Thursday. Went with MVFR during the best timing for some snow
showers/squalls however brief IFR should be expected in heavier
bands. Wind will generally continue out of the W to NW through
the TAF period with some gusts of 15-20 kts possible Thursday.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z FRIDAY...
FORECAST CONFIDENCE: High to medium.
ALTERNATE SCENARIOS: Brief drops in visibility and ceiling can
be expected with any snow shower through the TAF
period...however timing them is difficult.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06
CRW CONSISTENCY H H H H H H H H H H H M
HTS CONSISTENCY H H H H M M H H H H H M
BKW CONSISTENCY H H H H H H H M M M M M
EKN CONSISTENCY M M M M M M M M M M H L
PKB CONSISTENCY H H H H H H H H H H H M
CKB CONSISTENCY H H H H H H H H H H H M
AFTER 00Z FRIDAY...
Brief periods of IFR possible in snow showers into Thursday
night. IFR possible in snow Friday night into Saturday over
Virginia and southern West Virginia. IFR possible in snow Sunday
into Monday.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...JSH/RPY
NEAR TERM...JSH/MZ
SHORT TERM...RPY
LONG TERM...RPY
AVIATION...JSH/MZ
Area Forecast Discussion
National Weather Service Shreveport LA
912 PM CST Wed Mar 7 2018
.DISCUSSION...
Radiation cooling tonight with winds lgt areawide and mostly clear
skies except for some very thin cirrus in ne TX. Although upper
clouds become thicker further west, ruc data does not support
significant thickening of upper lvl clouds. Temps to cool to
within a couple or so degrees of dewpoints, and overnight lows
ranging from the lower 30s over sw AR to the upper 30s in ne TX
appear on track. No update needed./07/
&&
.PREV DISCUSSION... /issued 725 PM CST Wed Mar 7 2018/
AVIATION...
For the 08/00Z terminal forecast will prevail VFR flight
categories through the period. Surface high pressure will
continue to settle across the Four State Region which will allow
for the Northwest winds to gradually decrease and become light
and variable overnight and return to more Southerly for all but
parts of South Central Arkansas and North Central Louisiana where
the Northerly winds will become more Westerly. Some low
clouds/smoke near 3 kft may affect sites where daytime prescribed
burns occurred. Overnight mainly high level middle clouds and
high level clouds streaking over the area and more scattered to
few in coverage, with scattered to broken during the afternoon
Thursday. /06/
PREV DISCUSSION... /issued 348 PM CST Wed Mar 7 2018/
At 3PM, Conditions are breezy across the region with temperatures
mainly in the 50s. Northwest winds in the 15 to 20 MPH range will
subside after sundown as high pressure becomes nearly centered
over the ArkLaTex. Clear skies, calm conditions, and cool
temperatures are on tap for tonight. Lows will bottom out in the
30s areawide, with a few locations dipping to the freezing mark by
early Thursday morning.
Benign weather is anticipated for Thursday and Friday as surface
high pressure remains anchored over the region. Temperatures will
remain seasonable, with highs in the mid 60s and lows in the 40s
through Friday. Winds will turn around to the south on Friday as
high pressure slides east. This will bring a return of warm air
and gulf moisture to the region.
By Friday night, an area of low pressure will begin to organize
on the lee side of the Rockies. This area of low pressure is
expected to deepen and traverse across the Mid-South region
through Sunday morning. A warm front is expected to lift north
across the area during the day on Saturday igniting showers and
thunderstorms over the region. Plenty of surface instability will
be available for thunderstorms, but upper level dynamics look less
than favorable for organized severe weather to develop as the main
shortwave drops across southern Illinois. Nonetheless, a few
strong storms could be possible on Saturday along and ahead of the
cold front. Both main models are in good agreement on the timing
of the cold front swinging through the entire forecast area by
early Sunday morning.
Canadian high pressure will build into the region on Sunday. This
will bring a return of dry and cooler than normal conditions to
the region. Expect dry conditions and cooler than normal
temperatures to persist through midweek as the region remains
entrenched in northwest flow aloft.
/AC3/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 36 63 43 69 / 0 0 0 10
MLU 35 61 40 69 / 0 0 0 0
DEQ 31 61 39 64 / 0 0 0 10
TXK 33 61 42 67 / 0 0 0 10
ELD 31 61 41 69 / 0 0 0 0
TYR 37 64 45 69 / 0 0 0 10
GGG 35 64 44 68 / 0 0 0 10
LFK 38 66 44 70 / 0 0 0 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$