Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/22/19
Area Forecast Discussion
National Weather Service Cheyenne WY
427 PM MST Thu Feb 21 2019
.SHORT TERM...(This evening through Friday)
Issued at 330 PM MST Thu Feb 21 2019
Complex weather event upcoming the next few days as a low pressure
system moves out of the Colorado Rockies and intensifies across
northern Kansas over the next 24 to 48 hours.
Currently...Water vapor imagery showing an intense low over
southern California and southern Nevada this afternoon. Low is
slowly moving eastward towards southern Utah. Piece of energy
ahead of the low that moved through southeast Wyoming this morning
is currently moving into the northern Nebraska Panhandle. Strong
east to west gradient in place this afternoon with northeasterly
winds gusting to 30 mph out near Arlington this afternoon...with
25mph gusts from the northeast at Rawlins. Fairly widespread light
snow with area METARS reporting visibilities under 2 miles at
Douglas...Lusk and Torrington.
For tonight...Strong isentropic lift moves over CWA after 00Z
tonight being advertised on both the GFS and especially the NAM
out ahead of the low pressure system. Should see a break in snow
this afternoon with departure of shortwave over the northern
Panhandle. But after this lift begins...should see snow become
more widespread once again toward 03Z...continuing through the
overnight hours. Getting pretty good snow amounts for
Converse...Niobrara and northern Carbon Counties in southeast
Wyoming as well as the northern Panhandle through Friday morning.
HRRR concentrating heaviest snow over these areas tonight as
well. Decided to issue a Snow Advisory for these areas. Snow
ratios should be pretty high with very cold overnight lows down in
the single digits for most areas.
One issue to keep an eye on...our southern neighbors have a winter
weather advisory out for widespread freezing drizzle tonight. Am
not seeing it here on forecast soundings as moisture depth should
be deep enough to create all snow across our CWA. If it were to
happen...it would be over the southern Panhandle where the
shallowest moisture is being forecast. Current thinking is the
layer is going to be too deep for any freezing precip though...so
held off on adding to the forecast.
As the main low tracks into the 4 Corners area Friday and
eventually Colorado and New Mexico Friday night...we are going to
see another area of possibly heavy snowfall develop over the
southern Panhandle. GFS showing a .5 inch bullseye across the
southern Panhandle while both the ECMWF and SREF guidance showing
roughly .15 to .20 inches. After coordinating with our eastern
neighbor...decided to issue a Winter Weather Advisory for the
southern panhandle. Again...this will need to be watched closely.
If the GFS solution comes true...we could be upgrading these
advisories to warnings for Friday night/Saturday.
.LONG TERM...(Friday night through Thursday)
Issued at 330 PM MST Thu Feb 21 2019
Snow ends from west to east Saturday afternoon. We will see a
short reprieve in the weather for Sunday. By Sunday
afternoon...another low pressure system tracks into Montana.
Westerly winds will be on the increase as Craig to Casper
850/700mb height gradients increase above 50mtrs. Looks like a
high wind event for our wind prone areas...out ahead of the
associated surface cold front with this Montana low. Surge of
colder air pushes the arctic boundary back into place over the
Laramie Range behind this departing low.
Prolonged high wind event looking likely Monday through at least
next Thursday as we stay in zonal flow. GFS 700mb winds remain
strong. Monday and Tuesday look particularly strong as 700mb
winds increase to 60kts across much of southeast Wyoming.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 420 PM MST Thu Feb 21 2019
Wyoming TAFS...VFR at Rawlins, with occasional MVFR through 04Z.
VFR at Laramie, with occasional MVFR through 04Z, then IFR from
06Z to 15Z, then VFR. Occasional MVFR at Cheyenne until 02Z, then
IFR until 15Z, then MVFR until 19Z, then VFR.
Nebraska TAFS...MVFR at Chadron and Alliance until 03Z, then IFR
until 15Z, then VFR. IFR at Scottsbluff and Sidney until 15Z, then
MVFR or VFR until 19Z, then VFR.
&&
.FIRE WEATHER...
Issued at 330 PM MST Thu Feb 21 2019
Minimal fire weather concerns the next few days as most of
southeast Wyoming and Nebraska Panhandle experience a widespread
light snow event. Most areas should see at least an inch of snow
with the Panhandle likely seeing more. Looks to turn windy Sunday
and these winds could persist through much of next week. But we
have an arctic front in place along the Laramie Range that will
keep temperatures cold and afternoon humidity well above critical
levels.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory from 8 PM this evening to 5 PM MST
Friday for WYZ101-102-104.
NE...Winter Weather Advisory from 8 PM this evening to 5 PM MST
Friday for NEZ002-003-095-096.
Winter Weather Advisory from 5 AM Friday to 5 PM MST Saturday
for NEZ019>021-054-055.
&&
$$
SHORT TERM...GCC
LONG TERM...GCC
AVIATION...RUBIN
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Grand Junction CO
448 PM MST Thu Feb 21 2019
.SHORT TERM...(Tonight through Friday night)
Issued at 1229 PM MST Thu Feb 21 2019
The short term forecast remains on track this Thursday afternoon.
Our current storm system is currently centered over southern
California, and southwesterly flow aloft is in place over all of
eastern Utah and western Colorado. Upslope flow favorable for
snowfall across the southern foothills and San Juan mountains
continues with light to moderate snow falling throughout the day
from the US 160 corridor northward. While an anomalous moisture
stream is not present with this system, favorable mid and upper
level dynamics will support snowfall through the evening and
overnight. No major changes have been made to the current winter
weather headlines in place with this storm as forecast guidance
QPF amounts remain consistent and on track. The only changes to
the forecast through this event was to better time PoP values
across the western slope. Short-term high-res guidance has come
into better agreement regarding when exactly the heavier snowfall
will occur this evening and overnight. Convection currently
underway well to our southwest in Arizona was not handled well by
the HRRR or NAM Nest until recent runs. It now looks more likely
that a band of moderate to briefly heavy snow will enter southeast
Utah sometime around 6pm and track east and northward across much
of the Four Corners and western slope. This band of precipitation
will likely bring a brief period of snow to the Grand Valley, as
well as the US 50 corridor southward through Delta and Montrose,
sometime in the 10pm to 1am timeframe. Farther south, a more broad
area of light to moderate snow is likely to be ongoing through
out much of the evening and overnight along the 550 and 160
corridors. Eventually, the aforementioned band of heavier snow
will pass through this region as well, likely between midnight and
4am.
Low pressure will slowly shift eastward through Arizona on Friday.
This will keep a majority of eastern Utah and western Colorado in
a southwesterly flow regime. Accumulating snow will continue
throughout the day over the higher terrain, especially in the San
Juan mountains and southwest foothills of Colorado. The position
of the mid-level low suggests that a fair amount of wraparound
moisture will be thrown north of the San Juans, almost as far
north as the Grand Valley. With cold air firmly entrenched across
central and southwest Colorado, snow ratios will continue to run
on the higher end. Observations from SNOTEL sites in the higher
terrain suggest at least 20:1 in many spots, with slightly lower
ratios in the valleys.
Winter weather headlines drop off by 5pm on Friday afternoon.
Forecast guidance in the 12z model cycle lingers things a bit
longer than in previous runs as the upper-level low to the south
slowly lumbers eastward. Snow may hang on a bit longer than
expected tomorrow evening given the slow storm departure and
lingering wrap around moisture, especially as flow switches out of
the north. Will have to watch for possible extensions to
highlights in the San Juan Mountains if high-impact winter weather
is still ongoing after 5pm.
Drier air moves in from the northwest across all but the San Juan,
Sawatch, and west Elk ranges after midnight on Saturday. Low
temperatures have been adjusted downward from model blends, given
some clearing skies and fresh snowpack. These lows may need to be
trended downward even farther if more clearing is realized on
Friday night.
.LONG TERM...(Saturday through Thursday)
Issued at 1229 PM MST Thu Feb 21 2019
The long term forecast will be characterized by a bit of a pattern
change across the central Rockies. Recently, several high-
amplitude storm systems have dominated the forecast, with poleward
transport of cold air from the north and strong mositure streams
from the eastern Pacific. From Saturday afternoon through midweek,
a more zonal westerly flow pattern sets up over the western CONUS.
This pattern will not be devoid of moisture however. A strong
Pacific jet will remain in place over the northern Rockies, with
plenty of mountain snow lasting from Saturday through early next
week. Northeast Utah and northwest Colorado will remain on the
southern fridges of this moisture stream. For now, the most
likely time periods to see a bit of snow in the northern mountains
will come on Saturday night into Sunday morning in the Park
Range, and possibly on Wednesday afternoon into Thursday morning
in the Uintas, Park range and Flat Tops. Overall, temperatures in
the long range will remain at or slightly below seasonal averages.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 448 PM MST Thu Feb 21 2019
After a brief lull in some areas this afternoon, snow is starting
to pick up again in eastern Utah and southwest Colorado. IFR/LIFR
conditions will be common through the evening heading into Friday
morning. A band of snow looks to develop across the Utah-Colorado
border and track eastward impacting some of the central TAF sites
from 05Z through about 14Z with some reduction in VIS to MVFR/IFR
levels at times. Showers will again become scattered in nature
Friday afternoon with the focus shifting along the western
Colorado divide areas. Mountains will remain obscured and ILS
breakpoints will be met quite frequently.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 5 PM MST Friday for COZ003-009-010-
012-013.
Winter Weather Advisory until 9 AM MST Friday for COZ001.
Winter Storm Warning until 5 PM MST Friday for COZ017>023.
UT...Winter Weather Advisory until 5 PM MST Friday for UTZ023-025.
Winter Weather Advisory until 9 AM MST Friday for UTZ024.
Winter Storm Warning until 9 AM MST Friday for UTZ022-027-029.
Winter Storm Warning until 5 PM MST Friday for UTZ028.
&&
$$
SHORT TERM...MAC
LONG TERM...MAC
AVIATION...MDA
Area Forecast Discussion
National Weather Service Wilmington NC
952 PM EST Thu Feb 21 2019
.SYNOPSIS...
High pressure will build in from the north on Friday, before
sliding offshore on Saturday. Warm weather is then expected
Sunday ahead of a cold front that moves off the coast Sunday
evening. High pressure returns early next week.
&&
.UPDATE /THROUGH TONIGHT/...
As of 920 PM...Fog has returned offshore and is moving inland
along coastal locations this evening as evident on satellite
imagery. Patchy fog in some locations has dropped visibilities
to 1/2 mile or less at times.
Fog will continue into Friday morning. Temperatures are still
on track to drop Friday with highs ranging from the mid 50s to
the mid 60s with a back door cold front associated with a high
pressure moving offshore. Chances for light rain will increase
Friday.
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 315 PM Thursday...Much of the forecast area has broken out of
the stratus/fog and temperatures have quickly responded with a few
areas in the mid and upper 70s. Enough of a temperature gradient has
developed to allow a sea breeze to form, which has helped keep
temperatures down along the immediate coast. Otherwise, flat H5
ridging prevails across the Southeastern United States with dry
mid/upper air in place per water vapor imagery. In addition, the
subtropical jet is spreading deeper moisture across Mexico and TX
into the Plains, and the MS and OH Valleys. Although the subtropical
jet will shift toward east during the near term period the overall
pattern aloft will remain somewhat unchanged across the southeastern
States.
At the surface, a cold front will drop south across the forecast
area later tonight across the southeast NC zones and during Friday
morning across northeast SC zones. Stratus/fog is expected to
develop again this evening ahead of the front, possibly becoming
dense at some locations. The chance for showers will increase
tonight into Friday with UVVs overspreading the area in
southwesterly flow aloft and development of isentropic lift.
However, the higher QPF amounts are expected to be much farther west
and northwest of the forecast area through Friday night. Otherwise,
atypically warm overnight temperatures with temperatures falling
during Friday in the wake of the front will not for much in the way
of a diurnal range, especially for the northern half of the forecast
area.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 330 PM Thursday...High pressure north of the area Friday
night slides offshore on Saturday, but the high is quite strong
and the CAD setup over the local area should last through much
of the day except near the coast where temps may reach 60;
highs the 50s elsewhere. As far as rain chances...any precip
will be light and mainly confined to northern areas in the
morning hours. Fairly stagnant or even slowly rising temps into
Saturday night ahead of an approaching cold front. This front
crosses the area late Sunday, and any rain amounts will be quite
light due to the best forcing and moisture profiles staying
north of the local area. Highs mainly in the low/mid 70s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 330 PM Thursday...Dry weather returns to start the long
term period as surface high pressure builds in from the west.
The high slides offshore through midweek, as chances for rain
rise due to increasing warm air advection. Temps through the
period will be close to normal for late February...highs in the
60s with lows in the upr 30s to upr 40s.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
As of 00Z...All terminals other than LBT are currently in the warm
sector of a boundary pushing southward this evening. As the front
pushes southward, NE winds will filter in behind the front creating
a wedge and MVFR/IFR CIGs. Conditions will begin to deteriorate when
this wind shift begins and continue through the morning. Showers
will develop along this front, but anything that affects the
terminals will be light and isolated in coverage. Sea fog will
likely develop and lead to flight restrictions at CRE/MYR overnight,
especially MYR. If winds are slightly more northerly than
forecasted, impacts could be limited. By morning, the front should
be south of the area with all terminals in IFR/LIFR categories; some
drizzle is possible at inland terminals during the morning hours
with shower chances continuing elsewhere.
Extended Outlook...Front lingering in the area will lead to more IFR
CIG and/or VIS into Saturday as another round of overrunning rain
develops. Sub-VFR will likely prevail early Sunday before another
cold front pushes through lifting to VFR late Sunday and Monday.
&&
.MARINE...
As of 315 PM Thursday...Per satellite imagery shallow sea fog
continues across the adjacent coastal waters. Local procedures and
HRRR indicate that sea fog will likely continue tonight into Friday
morning, generally south of the cold front as it moves through. The
current Dense Fog Advisory is in effect through 4 PM and it may
need to be extended or re-issued for tonight.
The pressure gradient will remain weak ahead of the aforementioned
cold front. The front should clear the southernmost waters Friday
afternoon. A strong northeasterly pressure gradient will prevail in
the wake of the front as high pressure noses in from the north. The
strong northeasterly winds will persist Friday into Friday night with
a coastal trough taking shape by early Saturday morning. Seas will
be 3 to 5 ft in weakening swells this afternoon into tonight.
Steeper higher frequency waves are expected as the northeast fetch
becomes established Friday into early Saturday morning. A chance of
showers will also exist tonight into early Saturday morning.
Winds/seas slacken a bit into Saturday as a coastal trough
locates in the vicinity. 6 ft seas possibly return Sunday ahead
of an approaching cold front, which crosses the waters late
Sunday. High pressure and improving marine conditions then into
early next week.
&&
.TIDES/COASTAL FLOODING...
As of 315 PM...Minor coastal flooding is possible, especially with
the next couple of high tide at downtown ILM. Water levels will
likely fall a little short of thresholds for Wrightsville Beach.
Thus plan to issue a Coastal Flood Advisory only for downtown ILM
with high tide later this evening.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Coastal Flood Advisory until midnight EST tonight for NCZ107.
MARINE...Dense Fog Advisory until 7 AM EST Friday for AMZ250-252-254-
256.
&&
$$
SYNOPSIS...MAS
NEAR TERM...MCK
SHORT TERM...MAS
LONG TERM...MAS
AVIATION...21
MARINE...MAS/SRP
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Jacksonville FL
811 PM EST Thu Feb 21 2019
.UPDATE...Evening showers gradually fading as instability weakens.
SREF and HRRR models continue to show fog potential tonight...advecting
in from the Gulf and also forming over the Atlantic waters. Fog
may become dense by dawn Friday morning. Temperatures will
continue to be well above normal with lows tonight in the 60s.
Near record highs again expected on Friday.
&&
.AVIATION...VFR conditions this evening with clouds above 5000
feet. Expect fog and stratus to develop late tonight and Friday
morning with IFR conditions mainly in 09z- 15z time range.
&&
.MARINE...Light south to southeast winds through Friday around 10
knots with seas 3 to 5 feet. Expect sea fog to form again late
tonight and Friday as humid air remains over the cooler coastal
shelf waters.
Rip Currents: Low risk Friday with decreasing winds and seas.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 62 84 62 82 / 30 20 20 30
SSI 63 79 62 76 / 20 10 20 30
JAX 65 84 64 83 / 10 30 20 40
SGJ 67 80 64 80 / 20 20 10 30
GNV 65 85 64 85 / 10 30 10 40
OCF 67 86 65 85 / 20 20 10 40
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Zibura/McGinnis/
Area Forecast Discussion
National Weather Service Louisville KY
838 PM EST Thu Feb 21 2019
.Forecast Update...
Issued 836 PM EST Wed Feb 20 2019
Some quick updates to PoPs were made based on latest radar and model
trends. The NAM and HRRR seems to have a better handle on overall
QPF initialization and coverage vs the GFS/ECMWF, so the forecast
was leaned more toward those models. Rest of forecast remains on
track.
&&
.Short Term...(This evening through Friday)
Issued at 312 PM EST Thu Feb 21 2019
Mid-level shortwave energy is evident on water vapor imagery over
Arkansas, northern Louisiana, and western TN this afternoon. Copious
amounts of mid and upper level moisture will proceed to overrun the
relatively cool lower levels tonight. Despite the warm front
remaining to our south, expect light to occasionally moderate rain
to overspread central Kentucky this evening and overnight,
continuing into Friday.
These steady rains will remain south of the Ohio River for the most
part. QPF is highest across southern Kentucky, where 0.30-0.60
inches of rain is possible over the next 24 hours. Based on expected
rainfall rates, this shouldn`t cause significant additional
flooding. Minor river flooding will continue, of course. Areas along
and north of the Ohio River will stay mainly dry through Friday.
Lows Friday morning are forecast to be in the 33-41 degree range.
Highs Friday afternoon will reach the upper 40s to lower 50s.
.Long Term...(Friday night through Thursday)
Issued at 253 PM EST Thu Feb 21 2019
*********************************************************
** MORE HEAVY RAIN LATE FRIDAY NIGHT AND SATURDAY **
** SEVERE THUNDERSTORMS POSSIBLE SATURDAY EVENING **
** WINDY BEHIND COLD FRONT SATURDAY NIGHT AND SUNDAY **
** QUIETER WEATHER FINALLY EARLY NEXT WEEK **
*********************************************************
Friday Night - Saturday night...
Friday night low pressure will be developing INVOF the
Texas/Oklahoma Panhandle with a warm front reaching east. By sunrise
Saturday the warm front should be along/near the KY/TN border.
Overnight Friday a 50kt LLJ will impinge on the warm front with
southerly low level flow coming right up out of the western Gulf,
providing plenty of moisture for widespread rain. Rainfall amounts
of an inch or two will be possible, particularly over the southern
half of Kentucky closer to the best lift. Rumbles of thunder can be
expected but any thunderstorms will remain elevated above a low
level inversion in our position north of the warm front.
Saturday the Panhandle low will deepen and advance to Iowa. This
will pull the warm front to our north by mid day, putting us in the
warm sector for the afternoon. Temperatures should rise into the 60s
with dew points in the 50s. The widespread rain from Friday night
into Saturday morning will become much lighter and more spotty.
However, model atmospheric cross-sections indicate that a low
overcast will persist through the day. This will be significant as
that blanket of clouds will act to limit instability.
60kt winds will be found at 850mb Saturday and Saturday night ahead
of a strengthening 120kt 500mb speed max advancing from the Ozarks
to the mid-Mississippi Valley. Severe convection will break out
during the day from southern Missouri to east Texas and will race
ENEwd in the fast flow, arriving in the Ohio and Tennessee Valleys
by evening.
As the parent surface low heads into the upper Great Lakes it will
pull its cold front through here Saturday night. The storms will
line up ahead of that boundary. While instability is questionable,
it does look like there will be a narrow window of opportunity for a
thin ribbon of perhaps 500 J/kg SBCAPE to combine with plentiful
moisture and very strong bulk shear and low level helicity just
ahead of the front. This will be our best chance for severe weather.
All severe threats are on the table, though wet bulb zero heights
are a bit on the high side for severe hail.
Also, we must remember that these evening storms, though they will
be quick hitters, will bring yet more heavy rain to the region.
Rainfall totals from the warm frontal rain Friday night through the
cold frontal storms Saturday evening will likely be in the 1 to 3
inch range.
Sunday through Thursday...
West winds rushing in behind the departing system on Sunday will be
strong and gusty, possibly to advisory level especially in southern
Indiana and north central Kentucky. These winds may have a negative
impact on trees standing in waterlogged soil.
High pressure will then give us quiet weather Monday and Tuesday.
Rain chances may return for Wednesday and/or Thursday, though there
is disagreement among the models. In any case, it looks like those
rains, if they occur, would be light.
&&
.Aviation...(00Z TAF Issuance)
Updated at 612 PM EST Thu Feb 21 2019
Showers will move into southern and eastern Kentucky during the
overnight hours, affecting both the BWG/LEX terminals, and possibly
clipping SDF. Some reduced visibilities are possible in the heavier
showers. MVFR/IFR stratus will likely impact BWG through most of the
forecast period, while HNB/SDF/LEX remain VFR through the forecast
period. Showers will likely persist near the TN border through the
day tomorrow, while letting up across portions of central and
eastern KY.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...Flash Flood Watch from Friday evening through late Saturday
night for KYZ023>031-033>043-045>049-053>057-061>067-
070>078-081-082.
&&
$$
Update...DM
Short Term...EBW
Long Term...13
Aviation...DM
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1014 PM EST Thu Feb 21 2019
.SYNOPSIS...
A cold front will cross the region tonight. The front is
expected to then lift back to the north as a warm front this
weekend, resulting in a continued unsettled weather pattern.
High pressure will build in from the northwest early next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 1010 PM Thursday...Based on current wind observations,
cold front is slowly making its way through the CWA. A few
showers have developed over the far southwestern CWA, but per
latest high-resolution HRRR and 3km NAM forecast, think the bulk
of precipitation will hold off until after 06z and most likely
until after 08z-09z as the isentropic lift increases. PoPs
continue high, ramping to likely to categorical in most area
toward morning. No changes in the temperatures forecast. Current
mild readings in the 50s will drop into the 40s by morning as
cold front drops south of the area. A nice surge of NE winds
will develop, especially near the coast toward morning.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As of 245 PM Thu...The front will stall south of the area
Friday, as high pressure builds in from the north setting up
another CAD type situation with overrunning precip. Good
isentropic lift and deep moisture across the area will produce
more light to locally moderate rainfall. Will continue likely to
categorical pops through the day. Highs in the upper 40s to low
50s Friday, and could see highs early in the day and falling
during the afternoon.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 320 PM Thu...Mostly unsettled weather expected to the end
of the weekend with persistent cold air damming and a stalled
front to the south. A cold front crosses the region Sunday
ushering in a brief period of dry high pressure to start the new
week. Another round of unsettled weather is possible at the end
of the period.
Friday night through Sunday...Cold air damming will be ongoing
Friday evening with isentropic upglide over a stalled frontal
boundary positioned over GA/SC aiding in more soggy conditions
although QPF should be light - under a quarter of an inch. With
plenty of cloud cover, not forecasting lows beyond the low 40s. It
does appear there will be a non-diurnal temperature curve closer to
shore where a coastal trough will develop late overnight, although
how far the feature impinges on the coast (and thus how much
temperatures rise) is still a source of uncertainty. Numerical
guidance is generally too aggressive in eroding CAD-associated cold
wedges, and therefore will continue to favor cooler guidance. Like
yesterday, confidence in temperature forecasts are lower than
normal.
The coastal trough will persist off the coast and eventually push
inland late in the day Saturday. A non-diurnal temperature curve
appears probable Saturday night as the region comes under the
influence of WAA ahead of a deep surface low lifting into the Great
Lakes and associated cold front to the west. Models have slowed the
low and therefore the front slightly, and have moved PoPs up
slightly Sunday afternoon to account for this shift. Temps still
expected to climb into the low to mid 70s before the front comes
through. Breezy conditions still expected ahead of the front with
brisk SW winds of 15-25 mph, with some gusts up to 30 mph.
Sunday night through Wednesday...Dry high pres arrives late Sunday
with temps in the period generally in the low 60s. Wednesday
night/Thursday may see a return of unsettled weather, although still
uncertainty with its evolution and have kept only slight chance to
low-end chance PoPs this cycle. Confidence in this period is lower
than normal.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Short Term /through 00Z Saturday/...
As of 720 PM Thursday...Difficult aviation forecast continues
but will continue the previous forecast showing mostly MVFR for
all TAF sites through the night as the low-level flow gradually
veers from SW/W to NE as a cold front sinks south across the
region. Some patchy fog will be possible overnight, but the cold
front moving through should keep things fairly well mixed
preventing fog, but vsbys will be reduced in light rain that
will become widespread by 08z-09z and continue through the much
of the day on Friday.
Long Term /Fri night through Tuesday/...
As of 320 PM Thu...Above average confidence in sub-VFR Fri
night into Sat in an unsettled weather pattern, with good
chances of rain. Sunday afternoon will finally dry out with a
return to VFR expected. Breezy SW winds Sunday morning of 15-20
knots with gusts up to 25 knots are possible at all sites. VFR
conditions hold through Tuesday.
&&
.MARINE...
Short Term /through Friday/...
As of 1010 PM Thursday...No big changes to the marine forecast
as winds should gradually become N/NE at all marine locations
over the next few hours. A cold front will drop south across
the region overnight with a good CAA surge of NE winds
developing by early morning Friday. High-res models such as the
3km NAM and HRRR showing 15-25 knot NE winds early Friday
morning continuing into Friday evening. Seas will build to 4-6
feet in the advisory area tomorrow.
Sea fog has diminished over the past couple of hours per
observations and web cameras, but some lower vsbys still
detected over the northern Outer Banks. Will let the Marine
Dense Fog advisory continue until 1 AM.
Long Term /Fri night through Tuesday/...
As of 320 PM Thu...Poor boating conditions forecast through
most of the period in an unsettled weather pattern. SCA
conditions for outer srn and cntrl waters Friday evening subside
to 3-4 feet in N to NE flow behind a front to the south. Winds
veer to S Saturday evening at generally 10-15 knots as a coastal
trough drifts onshore. SCA conditions expected Sunday morning
ahead of a cold front. Seas forecast to build to 6-8+ft as winds
veer SW at 20-30 knots; a few gusts to gale force remain
possible in outer waters. Winds veer NW to NE through Tuesday
with seas decreasing to 1-3 ft srn and cntrl waters, 2-4 ft
north of Hatteras.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory from 5 AM to 10 PM EST Friday for AMZ152-
154.
Dense Fog Advisory until 1 AM EST Friday for AMZ156-158.
Small Craft Advisory from 6 AM Friday to 1 AM EST Saturday for
AMZ156-158.
Small Craft Advisory from 6 AM to 10 PM EST Friday for AMZ135.
&&
$$
SYNOPSIS...MHX
NEAR TERM...CTC
SHORT TERM...CQD
LONG TERM...HSA/MS
AVIATION...CTC/CQD/MS
MARINE...CTC/CQD/MS
Area Forecast Discussion
National Weather Service Phoenix AZ
628 PM MST Thu Feb 21 2019
.UPDATE...Updated aviation discussion.
&&
.SYNOPSIS...
A major winter storm will continue to affect the region tonight
before tapering off from west to east Friday. Precipitation will be
best east of the Lower Colorado River Valley. Significant
accumulating snow can be expected for elevations above 3000 feet
with very heavy snow above 4000 feet. Otherwise, expect much below
normal temperatures through Saturday before a slow warming trend
starts. A return to dry conditions are forecast into next week with
temperatures gradually warming back to near normals by late next
week.
&&
.DISCUSSION...
After a very active day today,which saw snow fall as low as 2500
feet over northern and eastern Maricopa County, and strong to severe
thunderstorms that produced gusty winds and small hail, more
widespread rainfall is developing across the region at this hour. The
latest high-res models are now showing light-moderate rain to
continue to fall across south-central AZ tonight, with snow above
3500-4000 feet. As the upper low draws closer later tonight, snow
levels as once again expected to fall to around 3000 feet. Latest
HRRR and NAM 3km model output is showing QPF amounts for the
remainder of the storm ranging from 0.05 in western Yuma County,
0.50 to 1.25 inches over the greater Phoenix area, up to near 2.00
inches over the higher terrain of south Gila County. Snowfall
amounts of over 2 feet are likely over the highest peaks. Needless
to say, travel is highly discouraged across the region, with more
road closures likely tonight and early Friday. Localized flooding is
a good bet, especially over the lower elevations of northern and
eastern Maricopa and Pinal Counties.
The steady rain/snow is expected to diminish to showers on Friday as
the main upper low center moves into the region and the main
moisture feed from the southwest begins to be cut off. Although
there will likely be a lot of breaks in the clouds by Friday
afternoon, the arrival of very cold air aloft (500mb temps in the -
30C to -32C range will likely destabilize the airmass enough to allow
scattered showers, and a few thunderstorms to develop. Some of the
stronger cells could briefly drop the freezing level low enough to
allow graupel, or even snow, to fall as low as as 1500-2000 ft
elevation.
Drier air will quickly work in from the west later Friday
with skies becoming mostly clear for the lower deserts by late
Friday evening. Freezing temperatures will once again be a
possibility in normally colder locations across the lower deserts.
After chilly daytime temperatures mostly in the 40s to around 50 for
the lower deserts, overnight lows into Saturday morning should again
end up around freezing. The coldest desert spots may dip into the
upper 20s to around 30 degrees.
The trough finally exits well to the east by Saturday morning with
dry westerly zonal flow taking over through Monday. Temperatures
will be slow to recover this weekend with highs still only in the
low to mid 50s Saturday over the Arizona deserts to around 60 in
the western deserts. Overnight lows Saturday night will again be
quite chilly, likely only a couple degree improvement over the
previous night`s near freezing temperatures. Models are now
leaning to a bit quicker of a warm-up next week with a weak ridge
building across the Western U.S. Tuesday into Wednesday. This
should allow highs to climb to around 70 degrees by Wednesday and
into the lower to middle 70s for the end of next week.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
The current winter storm system will continue to impact all
terminals through most of the 00Z TAF period. Stratiform light to
moderate rain is expected to persist through this evening and
possibly through most of tonight. Ceilings will continue to flirt
around MVFR, with CIGs as low as 2-3 kft and visibilities down to 3-
5 sm within showers. Showers are expected to scatter out and become
more isolated Friday morning. Wind directions will be tricky through
tonight due to the showers, creating some variability across the
Valley, but speeds should remain around 10 knots or less. Clouds and
visibilities should improve through Friday morning, after sunrise,
with CIGs rising to around 4-5 kft AGL by the afternoon. Additional,
wrap around isolated to scattered showers may develop across the
Phoenix metro Friday afternoon. Dry air is expected to arrive Friday
night, finally clearing skies.
Southeast California/Southwest Arizona including KIPL and KBLH:
The current winter storm system will continue to impact both
terminals through tonight. Gusty W to NW winds should subside
tonight and light showers should eventually taper off before sunrise
Friday. SCT o BKN clouds around 4-6 kft AGL will likely persist
through tonight, but may lower to 3 kft AGL at times in showers. Dry
NW flow is expected to clear the clouds at both terminals by Friday
afternoon. Gusty NW winds will pick up again Friday afternoon, with
up to 25 knots at KBLH and 20 knots at KIPL.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday: A strong winter storm will exit to the
east Friday night resulting in a drying and gradual warming trend
for the weekend into the middle of next week. Despite nearly
constant warming each day, highs will remain below normals through
next Tuesday although they will climb into mid to upper 60s over the
warmer lower deserts. Warmer deserts will finally approach normal
and reach the low 70s by next Wednesday. Humidity levels will remain
elevated through the period with drier deserts still mostly above 20
percent each day. Winds will tend to be on the light side during the
five day period.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Winter Storm Warning until 5 PM MST Friday for AZZ545-557-558-
560>563.
CA...Winter Weather Advisory until 10 PM PST this evening for CAZ560.
&&
$$
DISCUSSION...Percha/Kuhlman
AVIATION...Benedict
FIRE WEATHER...CB
Area Forecast Discussion
National Weather Service Blacksburg VA
857 PM EST Thu Feb 21 2019
.SYNOPSIS...
A frontal system is expected to become nearly stationary over
the region over the next several days as a series of low
pressure systems track northeast along the boundary. Each system
will produce widespread rain, possibly moderate to heavy at
times, increasing the threat for flooding of streams and
waterways.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 855 PM EST Thursday...
Dry period was short lived today as already seeing patchy rain
return across the west this evening associated with lift ahead
of another shortwave passing through the Tennessee Valley. This
in conjunction with the flow turning more southerly aloft
allowing moisture to overrun the cool pool to the north of the
front to the south. Rain will initially have to overcome much
drier air seen off the RNK sounding as it heads northeast with
guidance indicating the best convergence zone aloft across the
south later tonight once the developing wedge starts to take
shape. Still think some of this lighter rain will push out to
the Blue Ridge in the next few hours, and points east beyond
that so sped up pops while increasing into likely or categorical
levels most locations by daybreak per latest HRRR output. Any
freezing potential looks quite iffy espcly after such a warm
afternoon and soundings showing only weak easterly flow until
Friday so left out mention. This also supports bumping up lows a
bit per clouds and limited cooling potential given dewpoints,
until the wedge deepens which may result in lows occurring
after 12z.
Previous discussion as 345 PM EST Thursday...
Surface high pressure will build east and settle over New
England later tonight into Friday as yet another series of short
wave trofs begin to lift northeast toward the mid-Atlantic
region from out of the southern Plains and lower Mississippi
valley - steered by the flow between a strong upper trof over
the southwestern portion of the nation and an expansive upper
ridge along/off the Southeast coast.
Baroclinic zone will become established over/near the Blacksburg
forecast area later tonight and continue through Friday (and
well beyond)- with strong isentropic lift in 850-700 millibar
layer, good QC-forcing as warm moist advection over developing
surface wedge develops, and upward vertical motion fields
through increasingly saturated mid-troposphere are further
enhanced as right entrance region of 200-300 millibar jet
maxima becomes established over the area.
Ground conditions across much of the Blacksburg forecast area
already saturated or nearly saturated, with water levels
running high from previous rains and snowmelt. Rainfall totals
later tonight through the day on Friday expected to be
approaching an inch across the western portion of the forecast
area, with locally higher amounts possible - less east of the
Blue Ridge. Since higher amounts possible wherever east-west
banding of heavier rains become established, sufficient
confidence now exists that Flood Watch now warranted - beginning
in the mountains at Midnight tonight, and beginning east of the
Blue Ridge at 9AM on Friday.
As cool wedge intensifies over the area later tonight,
sufficient dry air may be entrained southward into the northern
fringe of the advancing rain shield to wet-bulb down
temperatures across the higher elevations of western Greenbrier
County WV to wring out a little freezing rain on elevated
surfaces. However, a relatively warm ground combining with
limited areal coverage does not warrant issuance of any headline
at the present time, and choose to keep focus on much bigger
developing threat - the potential for flooding rains.
Temperatures under cool wedge will again remain relatively
consistent through the near-term period...mainly mid 30s to
lower 40s in the mountains to the lower and mid 40s across the
Piedmont.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 345 PM EST Thursday...
High pressure will be centered over New England Friday evening, then
wedge south into the Carolinas Friday night. Meanwhile, an upper
level ridge will take position just east of the Bahamas, Turks and
Caicos Islands. The outer rings of this ridge will be draped
across southern Virginia and North Carolina into Sunday morning.
Short waves tracking on these outer rings will bring warm moist
air over the south portion of the wedge, producing periods of
light to moderate rain. Models are showing a warm front aloft
with significant isentropic lift generating an axis of moderate
rain (half to one inch of rain) along the VA/NC border Friday
night, Highway 460 corridor Saturday morning, and I-64 corridor
Saturday afternoon. Storm total rainfall amounts will range from
two to three inches across the mountains and one to two inches
east. The Weather Prediction Center (WPC) has the area
highlighted for excessive rainfall Friday night into Saturday
night with a slight risk over the mountains. With all this in
mind, a Flood Watch has been issued with the afternoon package.
Needless to say, with rain falling into a wedge of cooler air,
temperatures will not move much Friday night into Saturday night,
especially across the foothills and piedmont counties. Temperatures
inside the wedge will range from the upper 30s to lower 40s. Where
the wedge erodes (Richlands, Bluefield, and the Mountain Empire of
SW VA ), milder temperatures are expected to range from the mid 40s
to mid 50s.
The wedge will erode quickly Sunday morning as a cold front sweeps
across the region. This strong front will be pushed across the area
by a closed low over the Great Lakes. Even though the front is
tracking over the area in the morning, dynamics are good for a
chance of thunder to be heard. Convection associated with the front
could produce another quarter to half of an inch of rain Sunday
morning. Rain exits the area by Sunday afternoon, then the winds
will begin to blow. Sharp pressure rises and a broad +60kts low
level jet behind the front will bring strong and gusty northwest
winds across the entire forecast area. The strongest winds will
occur just behind the front Sunday afternoon and evening. Breezy and
gusty S-SW winds are also possible ahead of the front, but to a
lesser extent. However, with a wet ground, sub advisory level wind
speeds and gusts couple topple trees and cause power outages.
With the colder air lagging behind the front by a few hours,
temperatures are excepted to peak in the mid to upper 50s across the
mountains and into the 60s east. A cold blast of air will send
temperatures down into the 20s west of the Blue Ridge to lower 30s
east.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 345 PM EST Thursday...
Winds will begin to subside Monday as high pressure builds over the
region. This cool high pressure will not stay long, moving out to
sea Tuesday night. A northern stream cold front will join forces
with a southern stream disturbance late Tuesday night/Wednesday
morning to bring a chance for rain back into the area. At this time,
the two do not phase until both systems move off the Mid Atlantic
Coast Wednesday evening. Dry high pressure will follow with no rain
expected until the weekend.
Near normal temperatures are expected for the next week.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
As of 615 PM EST Thursday...
Weak high pressure building southeast into the Blacksburg
terminal forecast area has allowed for gradual improvement back
to VFR conditions early this evening.
Despite improvement, which is expected to linger into mid
evening, lower clouds will again be on the increase as the
night progress as next, in what will become a series of weather
disturbances during the next several days, slide north and east
across the terminal forecast area. This will result in
deteriorating flight conditions across the entire area back into
MVFR to IFR range by daybreak Friday, and once established,
will likely persist at times in rain and fog through Saturday
night. Winds will again turn northeast and then easterly later
tonight into Friday night with speeds of 5-15 kts except locally
higher with more southeast flow into KBLF by Saturday.
Medium to high confidence in ceilings and visibilities during
the next 24 hour terminal forecast period.
Extended Aviation Discussion...
Cold front is expected to sweep east through the terminal
forecast area on Sunday, gradually diminishing/ending the threat
for precipitation with subsequent return to VFR conditions east
of the Blue Ridge by/during the afternoon.
However, colder upsloping winds from the west or northwest
following the frontal passage will likely maintain the threat
for sub-VFR weather west of the Blue Ridge through Sunday
night, and perhaps even through much of Monday.
Winds may also become quite strong and gusty behind the front
Sunday into Monday, especially over the mountains, until high
pressure can sufficiently build into the region later Monday
into Tuesday - thereby allowing winds to gradually relax.
Medium to high confidence in ceilings and visibilities during
the next 24 hour terminal forecast period.
&&
.HYDROLOGY...
As of 345 PM EST Thursday...
A quasi-stationary frontal boundary will remain over or near the
Blacksburg forecast area during the next several days as a
series of weather disturbances lift northeast along the
boundary. Each system will bring a period of widespread rain,
possibly moderate to heavy at times. Rainfall totals over the
next several days are expected to be in the 2 to 4 inch range in
many areas, with locally higher amounts quite possible. Runoff
from rain falling on a saturated or nearly saturated ground will
increase the threat of flooding on area streams and waterways.
Ensemble River Forecasts reflect minor to potentially moderate
flooding of most major waterways and associated tributaries.
If this threat appears like it will materialize, appropriate
Flood Warnings will be released. Stay tuned...
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch from midnight EST tonight through late Saturday
night for VAZ007-009>020.
Flood Watch from 6 AM EST Friday through Sunday morning for
VAZ022>024-032>035-043>047-058-059.
NC...Flood Watch from midnight EST tonight through late Saturday
night for NCZ001-002-018.
Flood Watch from 6 AM EST Friday through Sunday morning for
NCZ003>006-019-020.
WV...Flood Watch from midnight EST tonight through late Saturday
night for WVZ042>044-507-508.
&&
$$
SYNOPSIS...WERT
NEAR TERM...JH/WERT
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...JH/WERT
HYDROLOGY...WERT
Area Forecast Discussion
National Weather Service Topeka KS
946 PM CST Thu Feb 21 2019
.UPDATE...
Issued at 946 PM CST Thu Feb 21 2019
Have updated the forecast to push back the start of POPs Friday
morning until the mid and late morning hours. The 18Z and now 00Z
NAM along with the RAP and HRRR have shown the low level moisture
advection to hold off until the 15Z to 18Z time frame. With the
00Z RAOB showing pretty dry low levels and no significant moisture
upstream across central MO, think the saturation of the low
levels will be slower than the prev forecast indicated. This
should also curtail the potential for freezing drizzle as
temperatures are expected to be warming through the mid 30s as the
precip potentially begins. There is still an outside shot for a
brief period of freezing drizzle across east central KS, but the
probabilities remain to low at this time to consider an advisory.
&&
.SHORT TERM...(This evening through Friday)
Issued at 300 PM CST Thu Feb 21 2019
For tonight into Friday, the base of a high-amplitude midlevel
trough will continue to close off over the Lower Colorado River
Valley, east of which a long fetch of southwesterly flow aloft will
flank a broad southeastern states ridge. This pattern will
facilitate a strengthening lee trough over the High Plains, as
height falls / DCVA preceding the trough overspread the Rockies
Front Range. Poleward transport of partially modified Gulf moisture
will facilitate the northward spread of stratus through the night,
with sufficiently deep saturation late tonight into Friday
supporting patchy drizzle. With the antecedent modifying polar
air mass, localized freezing drizzle cannot be ruled out. However,
present indications are that the stronger forcing for ascent and
deepening cloud layer supporting precipitation growth may be
delayed until after the cessation of sub-freezing surface
temperatures in many areas, which should mitigate the potential
for freezing drizzle. Nevertheless, localized slippery surfaces
may occur late tonight into Friday morning before temperatures
rise above freezing through the day. By Friday afternoon, an
increasing moisture influx will facilitate greater coverage and
intensity of precipitation, with high temperatures expected to
reach the upper 30s to lower 40s.
.LONG TERM...(Friday night through Thursday)
Issued at 300 PM CST Thu Feb 21 2019
The aforementioned closing-off upper low will quickly
eject northeastward from the southern Rockies to the upper Great
Lakes Friday night to Saturday night. The compact nature of this
cyclone will result in very strong geostrophic adjustment processes
in association with an upper jet streak flanking the upper low to
its south. Intense forcing for ascent within the left-exit region of
this jet streak will spread across the region, and phase with strong
frontogenetic ascent through the lower/middle troposphere amid a
bifurcated warm-conveyor structure in support of widespread
precipitation. Through mid-day Saturday, much of this activity
will be in the form of rain with elevated parcels accompanied by
adequate buoyancy in support of weak-thunderstorm potential.
Pockets of freezing rain cannot be ruled out across parts of
northern Kansas, conditional upon surface temperatures remaining
marginally below freezing -- a low-confidence scenario.
As the intense upward motion overspreads the area, deep surface low
pressure is expected to track northeastward across Kansas, with
strengthening cold advection to the west and north of the track of
the surface low. Thermodynamic profiles in the low levels will
rapidly cool in association with the cold advection, with rain
quickly changing to snow from west to east through the afternoon.
Strong winds are also expected in association with the tight
pressure gradient peripheral to the surface low. With the forcing
for ascent quickly shifting northeastward, the most likely phasing
of strong winds and possible blizzard conditions will exist along
and northwest of a Council Grove to Hiawatha line where a Winter
Storm Watch has been posted, and 2-6 inches of snow may accumulate
through Saturday evening. Significant blowing/drifting of snow will
be possible. Elsewhere, lower snow accumulations may mitigate the
overall impact from this system to some extent, though sufficient
dispersion among model solutions exists to warrant concern for
hazardous winter-weather conditions even outside of the Winter Storm
Watch area. The Winter Storm Watch encompasses the most-likely area
of dangerous winter-weather and potentially blizzard conditions, and
the areal delineation of the Watch may be adjusted in subsequent
forecasts.
Following the departure of the strong storm system by later in the
weekend, a trailing mid/upper-level jet stream is forecast to
persist across the northern states. While embedded disturbances
transiting this feature may reinforce polar air over the area at
times through next week, stronger forcing for ascent will be
displaced well to the north of the area. As a result, mostly dry
conditions should persist across the region. Light snow could move
across the region for Monday night in association with one of the
disturbances, and this could be followed by wind chill readings in
the single digits above and below zero in parts of northern Kansas
for Monday night and Tuesday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday)
Issued at 530 PM CST Thu Feb 21 2019
A low level warm air advection pattern is expected to persist
through the day Friday. Eventually this will lead to IFR CIGS and
some drizzle or light mist. Most guidance shows the low level
moisture surge holding off until the late morning hours. This is
expected to limit chances for FZDZ as temps warm above freezing.
Confidence in the deteriorating conditions is high. Timing the
category changes is the biggest uncertainty and may need
adjustments as the weather unfolds.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Saturday afternoon through Saturday
evening for KSZ008>012-020>024-034>038.
&&
$$
UPDATE...Wolters
SHORT TERM...Cohen
LONG TERM...Cohen
AVIATION...Wolters