Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/26/19

Area Forecast Discussion

National Weather Service Bismarck ND

 939 PM CDT Mon Mar 25 2019

.UPDATE...
Issued at 928 PM CDT Mon Mar 25 2019

The main forecast concern continues to be fog potential. Latest
RAP forecast soundings continue to indicate a better potential for
stratus than fog. Mesoscale models continue to indicate the
potential for low visibilities. Currently, Hettinger is the only
station in the area with a reduction in visibility and they are 4
miles. See no need to deviate from current forecast with areas of
fog, mainly after midnight and no need for a dense fog advisory at
this time. We did bump up sky cover in the far west this evening,
and decreased clouds a bit after midnight. If sky clears in the
far west late tonight we could see some radiational fog but with
increasing southwest winds just above the surface, think this
potential is also minimal.

UPDATE Issued at 533 PM CDT Mon Mar 25 2019

There may be a sprinkle or flurry over the far southwest late this
afternoon, otherwise precipitation chances have ended. The main
issue tonight for the southwest will be fog development. Mesoscale
models are hitting this area pretty hard for fog potential late
this evening through tomorrow morning. BUFKIT soundings do
suggest more potential for stratus than fog, but for now will
monitor.

Otherwise just populated latest sensible weather elements and
blended to early evening values. Updated text products will be out
shortly.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 235 PM CDT Mon Mar 25 2019

A weak shortwave embedded in the upper ridge to our west
continues to slide southeast across our far southwest where a
slight chance of drizzle, freezing drizzle, or light rain/snow
remains over the next couple of hours.

Expect more fog to develop overnight across roughly the western
third of the state. As the ridge axis begins to move into the
state, light southerly flow and abundant moisture at the surface
will promote the potential for another Dense Fog Advisory but will
defer to the evening shift as trends and guidance should come
together a bit better as we reach sunset regarding exact
placement. Fog may very well stick around until lunch time before
lifting. Clouds should gradually begin to clear across the west
through the afternoon.

With the ridge axis pushing over the area Tuesday, most of the
forecast area will see much warmer temperatures. Western locations
will climb to well above average with widespread highs in the 60s
and possibly the lower 70s. The one detail that could put a wrench
in the high temperature forecast would be cloud cover. We should
see enough clearing in the west to reach these temperatures in the
northwest but fog has been stubborn to lift over the southwest
the past few days and that will have quite a bit of impact
regarding temperature potential if it sticks around again.

.LONG TERM...(Tuesday night through Monday)
Issued at 235 PM CDT Mon Mar 25 2019

Although the ridge starts to flatten Wednesday as a trough swings
through the northern stream, mild temperatures will continue. A
secondary trough slides in from the west late Wednesday into
Thursday, bringing rain or snow chances to the southwest, along
with cooler temperatures. Temperatures remain near normal to end
the work week going into the weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 928 PM CDT Mon Mar 25 2019

Mainly VFR conditions to begin the 00Z TAF forecast period this
evening. The exception is KDIK where areas of fog and stratus are
likely to remain through the night, before lifting during the
morning on Tuesday. Elsewhere, VFR ceilings this evening will
become MVFR late tonight into early Tuesday morning as a weak
frontal boundary moves from western into central North Dakota.
Winds will remain generally southerly around 5-10kts through the
forecast period.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...TWH
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...TWH



Area Forecast Discussion

National Weather Service Blacksburg VA

 1056 PM EDT Mon Mar 25 2019

.SYNOPSIS...
A cold front will slide to the southeast of the region this
evening and then offshore overnight. Drier but cooler weather
returns for mid-week as high pressure builds back across the
area from the north Tuesday into Wednesday. The high exits
offshore later in the week resulting in much warmer temperatures
heading into Friday and Saturday.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 1050 PM EDT Monday...

Main concern this hour is areas of dense fog developing along
and west of the Blue Ridge, especially through the New River
Valley and along/west of I-77. Feel this may continue for
several hours until drier air advects southwest from northern VA
overnight, mainly after 09Z in the west. Thus, issued an SPS to
cover the situation. The main area of rain has moved off to the
east and may linger a while along our southeastern border, but
for the most part is expected to remain south/east of our CWA.
Another area of rain associated with the upper trough lingers in
the western areas and this should progress toward the New River
Valley over the next few hours, then dissipate as the drier air
works southeast into this region before daybreak. The New River
Valley will likely also see drizzle linger the longest as it
becomes a convergence zone between the moist air across the
southwest and the drier air approaching from the northeast, at
least until around daybreak.

Temperatures and dewpoints were pretty well on track, so most
adjustments were to shaping the pops better to match the most
recent obs and latest runs of the HRRR/NAMNest.

One other note, is that northeast winds will become a bit strong
and gusty across the eastern areas later tonight, but should
remain below wind advisory criteria.

As of 630 PM EDT Monday...

No major changes are in the plans for the forecast update early
this evening. Precipitation is concentrated the greatest across
the southern and eastern sections of the forecast area, nearest
the departing front. The area near and north of Interstate-64
is experiencing either an end to the rain there, or at the most,
has some remaining sprinkles. Light precipitation is still
expected to redevelop across this area as we progress into
tonight with northeast winds pushing lingering low level
moisture upslope into the mountains. The thunder threat has
shifted east of the area, so have removed any additional mention
from the forecast. Have tweaked hourly temperatures and dew
points to better match the current conditions and the expected
trends through the evening hours.

As of 222 PM EDT Monday...

Initial band of showers continues to work east across the
region this afternoon and should spill to the southeast of the
area this evening. Still some potential for an isolated storm
far southeast ahead of the trailing strong upstream shortwave
and where seeing faint instability, but iffy at this point.
Otherwise will continue with high pops from northwest to
southeast through sunset espcly given possible added upstream
showers with the main wave aloft to the west. However still
appears overall low QPF of around a quarter inch or so.

Once the surface wave/front sag to the southeast early this
evening will see an influx of increasing low level northeast
flow that will progress from northeast to southwest tonight.
Models suggest that a convergence zone may develop along the
southern Blue Ridge as the upper wave passes while an inverted
surface trough develops. This scenario remains uncertain espcly
given decreasing depth to the moisture but appears enough to
warrant a continuation of higher pops mountains through at least
midnight before gradual drying from the north/east wins out.
Since similar to the HRRR and FV3, bumped up pops a bit more
through the evening west where may change to flurries or spotty
light snow before ending late. Think enough drying to preclude
much in the way of pops needed northeast, but still cloudy and
turning chilly with lows 30s/40s except for a few 20s far north.

Upper trough to remain over the region Tuesday as surface low
pressure moves east and strong high pressure to the north wedges
in east of the mountains. Guidance showing a pronounced shot of
drying heading in from the northeast during the day on northerly
winds, with only the far southwest perhaps still stuck under
some cloud cover during the afternoon before clearing. Otherwise
looking at increasing sunshine from northeast to southwest into
the afternoon under rapidly decreasing moisture within the
column. However will remain cool under the 850 mb cold pool
that will result in a rather deep north/northeast trajectory
that should hold temps below guidance (mainly 50s) despite the
developing sunny skies.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 230 PM EDT Monday...

High pressure center over New York Tuesday night will slide east
into Thursday night. Low temperatures Tuesday night will range from
the mid 20s in the mountains to the lower 30s in the piedmont under
mostly clear skies.
As high pressure slides off the Mid-Atlantic region Wednesday,
return flow will set the stage for a warming trend across the region.
With a dry airmass and good mixing, low afternoon relative
humidities are expected Wednesday afternoon with values into the 20
to 25 percent range, with light east to northeast surface winds. The
light winds should help alleviate any significant fire weather
concerns. Under full sunshine with strong subsidence, high
temperatures Wednesday will warm into the mid 40s in the mountains
to the mid 50s in the piedmont. Mostly clear skies continue
Wednesday night with low temperatures generally in the lower to mid
30s. Warming trend continues on Thursday, high temperatures will
climb in the lower to mid 60s with lows mainly in the 40s.

Forecast confidence is overall high for this period.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 230 PM EDT Monday...

The surface high pressure will push further offshore Friday allowing
deepening warm advection to develop ahead of another cold front
which arrives over the weekend. The combination of sunshine under
strong ridging/warming aloft per 850 mb temperatures climbing to +10
deg/C or higher should result in above normal temperatures from
Friday onward. A weak vort max rotating around the upper ridge may
create an isolated shower in northern Greenbrier Friday afternoon.

A stronger shortwave and richer moisture ahead of the main cold
front may create scattered showers mainly mountains Saturday into
Saturday night and elsewhere on Sunday. The models have different
solutions with some more progressive and consolidated evolution
compared slower and wetter. Decided to utilize WPCGuide with a more
progressive system for weekend into early next week. Highs on Friday
and Saturday will be from mid 60s to the lower 70s. Low temperatures
Friday and Saturday night will be generally in the 40s. High
temperatures Sunday will vary from the lower 50s in the mountains to
the upper 60s in the piedmont. Cooler temperatures are expected
MOnday with highs from around 50 in the west to the lower 60s in the
east.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
As of 715 PM EDT Monday...

The main area of precipitation associated with the passing front
is now focused across the southeastern sections of the forecast
area. And end of precipitation, or at most some lingering
sprinkles, was noted across the northern sections around the
I-64 corridor and points north. The main area of rain will
continue to exit the region to the southeast. However, northeast
low level flow will help keep moisture to banked up against the
mountains, through most of the night. This will keep, or return,
light precipitation to mainly western areas along with keeping
sub-VFR conditions in this area.

Eventually, the drier air will win out, allowing for a trend to
VFR conditions starting mainly after daybreak Tuesday morning in
the north once the nocturnal inversion breaks.

Lingering low cigs/vsbys will improve from north to south
Tuesday morning with most locations bouncing back into VFR under
drier north/northeast flow Tuesday afternoon.

Confidence in the above aviation forecast is moderate on
average. While the general trend is expected to be on target,
the specifics reflected in the the individual TAFs as to which
which terminals have a better potential to be IFR vs MVFR is
more challenging.

EXTENDED AVIATION DISCUSSION...

VFR under strong high pressure should prevail Tuesday night
through Friday with northerly winds gradually becoming southwest
by the end of the week.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...JH
NEAR TERM...DS/JH/RAB
SHORT TERM...KK
LONG TERM...KK
AVIATION...DS/JH/PM