Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/16/20
Area Forecast Discussion
National Weather Service Albuquerque NM
559 PM MDT Sun Mar 15 2020
00Z TAF CYCLE
Eastern NM will remain socked in with low clouds and areas of BR and
FG well into Monday morning. LIFR to IFR conditions will prevail
through this area. There may be a little drizzle or light rain in the
northeast this evening. VFR conditions will prevail central and west.
.PREV DISCUSSION...300 PM MDT Sun Mar 15 2020...
Low clouds and patchy fog will continue across the east again
tonight. Monday will be sunny and warmer, but clouds and
thunderstorms increase across the eastern plains on Tuesday ahead of
the next storm system. Widespread wetting precipitation, including
thunderstorms, high elevation snow showers, breezy to windy
conditions, and cooler temperatures will sweep through the state
Wednesday and Thursday. Wind gusts up to 50 mph will be possible
along and east of the central mountain chain, particularly on
Thursday. Friday will be slightly warmer and drier, but
precipitation chances return to the northern mountains on Saturday.
.DISCUSSION...(TONIGHT THROUGH MONDAY NIGHT)...
Based on current radar trends, not expecting much more than light
rain or drizzle for the rest of the day across the plains. That said,
the HREF and HRRR continue to show a shower or storm developing
northwest of KLVS later this afternoon where the sun is still trying
to peak out. Therefore, if anything more substantial were to develop,
it would probably be around this location.
Otherwise, low clouds and fog will persist through the overnight
period across eastern NM. It is likely that the low clouds and fog
will nudge up against to the central mountain chain overnight, and
perhaps squeak through Glorieta Pass and move over Santa Fe briefly.
Dense fog is probable again tonight, and would not be surprised to
see more widespread Dense Fog Advisories issued. The fog and low
clouds should clear out from west to east Monday morning, as dry,
southwest winds aloft mix down to the surface. Low clouds may linger
in the southeast til noon or shortly thereafter. Still expecting
some light southwest breezes in the afternoon Monday with at or
above normal temperatures.
Expect the moisture that was scoured out to return across portions
of the plains Monday night. A weak front nosing into NE NM may also
cause concern for low clouds and/or fog.
LONG TERM...(TUESDAY THROUGH SUNDAY)...
Gulf moisture will be pushing northward into the Land of Enchantment
on Tuesday ahead of the next storm system currently off the coast of
central California. Both models have low-level moisture pushing into
eastern New Mexico, but the NAM doesn`t have it mixing out during the
day. There is an SPC slight risk barely bordering Curry and
Roosevelt counties. Should the moisture stay in place, there will
be better chances for thunderstorms across the plains, and
potentially severe weather as well. Steep mid- level lapse rates and
and robust low- level moisture should provide enough instability for
these storms, should they develop.
By Wednesday, the southernmost low in the coupled system will begin
to approach the Four Corners region. Precipitation will start out as
rain across much of the state Wednesday, but 700 mb temperatures
will drop to -8/-9 C Wednesday night as the core of this system
moves overhead. The northern mountains could accumulate several
inches of new snow, along with the western high terrain. This could
be a more widespread snow event than the storm seen late last week.
Breezy to windy conditions are also expected Wednesday, and
especially Thursday, with the passage of the Pacific cold front. Wind
gusts could reach upwards of 50 mph along and east of the central
mountain chain, but High Wind Warnings don`t seem out of the question
at this point.
Precipitation chances gradually diminish by late Thursday. Temperatures
warm slightly on Friday with southwest flow aloft, but will still be
below normal for mid to late March. Precipitation chances increase
across the northern mountains Saturday as a weak upper-level trough
It is unclear what happens to the aforementioned northern low, as
part of the double- barreled system, as the GFS wants to absorb it
into the next system. Some uncertainty gets thrown into the forecast
at this point, but unsettled conditions seem to remain through early
Widespread low clouds and patchy fog will continue to impact eastern
NM through tonight, before clearing out late Monday morning, as dry,
southwesterly flow mixes down to the surface. Meanwhile, light
southwest breezes and above normal temps will continue through the
rest of the day across western NM. Near to above normal temperatures
are expected area wide for Monday. Good or better vent rates are
also expected for Monday. On Monday night, the moisture will slosh
back into the plains and may set the stage for a few thunderstorms
across far eastern NM on Tuesday afternoon. Elsewhere, southwest
breezes will pick up a few more notches, and vent rates will improve
accordingly. Another round of widespread precipitation is expected
Wednesday through Wednesday night, with orographic lift allowing
precip to continue over the mountains on Thursday. Initially, most
of the precip will fall as rain, but snow levels will lower
Wednesday night to between 5500 and 6500 feet. On Thursday, strong
westerly winds are expected, particularly so across eastern NM where
wind gusts could exceed 50 mph.
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
902 PM CDT Sun Mar 15 2020
Issued at 859 PM CDT Sun Mar 15 2020
Overall the forecast is in good shape. Radar is indicating some
potential drizzle/fzdz developing over the James valley, and
soundings to some degree support that with weak LL omega over a
fairly deep LL moisture layer. All the clouds and some mixing will
keep temperatures relatively mild overnight.
.SHORT TERM...(This Evening through Monday Night)
Issued at 245 PM CDT Sun Mar 15 2020
Taking a look at the current surface weather picture, strong high
pressure was across north central MT and much of southwestern Canada.
A trough was set up over the far western Dakotas was extending from
far southwestern WY/southern ID/UT/NV area. At 500mb mainly zonal
flow continues, with a large low off the northern CA/OR coast, and a
secondary trough over Alberta/Saskatchewan. This was bringing some
energy across ND, with light precipitation through much of the day.
Farther south light snow, and potentially freezing drizzle only
briefly moved along the ND/SD border today. The surface trough
crossing central SD late tonight and exiting to southeastern SD by
midday Monday will bring with it a light wintry mix of
precipitation. While the HRRR and RAP13 do indicate a higher
potential move over central SD overnight, have just gone with slight
chances for the most part. Will need to monitor the latest trends on
this one. Have highlighted the potential for freezing drizzle in the
HWO over the Prairie Coteau overnight as surface temperatures fall
below freezing and there isn`t much of a freezing layer aloft to
produce dendrites. Still, expecting little to no accumulation.
Dry high pressure will build in from the northwest Monday afternoon,
and linger across the listening area through much of Tuesday. So
we`ll still be cool with highs Monday in the mid to upper 30s, with
temperatures about 5 degrees below average for this time of year.
.LONG TERM...(Tuesday through Sunday)
Issued at 245 PM CDT Sun Mar 15 2020
Will start the period with high pressure in place, gradually
shifting east and giving us low level easterly flow. NAM and GFS
BUFKIT profiles indicate a layer of saturation through around 6kft,
with enough weak warm advection that this may push the lowest part
of that layer above freezing, while the top part of the profile
stays outside the range of the dendritic growth zone. This would
present as drizzle thanks to weak low level isentropic ascent. Given
ground temperatures above freezing, freezing drizzle shouldn`t be an
issue. Deterministic guidance has a decent degree of consistency
concerning a low developing in Wyoming and ejecting into Nebraska.
This will enhance ascent across the CWA, however a storm track
currently south of Omaha means the southern half of the State will
be the focus area for any winter weather. BUFKIT profiles this far
north show saturation throughout the column, however lift is well
above the dendritic growth zone. As the low develops we also see a
northwest to southeast gradient of around 20-30mb across the state,
and pressure rises about 13mb/6hrs. 1/2 km winds are also around
50kts. 925mb temperatures under a 1040mb high that follows are about
2 standard deviations below climo, so it will feel a bit like we`ve
moved back into winter for a bit next weekend.
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 621 PM CDT Sun Mar 15 2020
IFR/MVFR cigs are expected through the night at all terminals.
Patchy freezing drizzle is also possible, especially around KATY.
Some improvement in the cigs will come Monday afternoon.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
905 PM PDT Sun Mar 15 2020
.SYNOPSIS...Cool and showery conditions will continue overnight
and into Monday morning, mainly south and east of the Golden Gate.
Showers will diminish by Monday afternoon. Drier weather is
expected from Tuesday through the end of the week, but rain
chances will continue at times through at least Thursday. Another
weather system may then bring more widespread precipitation to
the region next weekend.
.DISCUSSION...As of 9:05 PM PDT Sunday...A nearly stationary
upper low remains centered just off the northern California coast
this evening. To the south and east of the low, bands of showers
continue to track inland across the central and southern San
Francisco Bay Area, as well as the Monterey Bay Area. Rainfall
rates are mostly light this evening, but similar to last night
there have been locally moderate to heavy rain rates around
Watsonville and north and east across portions of the Santa Cruz
Mountains and Diablo Mountains. The 00Z NAM and latest HRRR both
indicate that shower activity overnight will mostly be confined to
areas where rain is currently falling, with highest amounts
expected across the southern half of our forecast area. Based on
the NAM and HRRR, a half inch to an inch of additional rainfall
is likely through Monday morning from San Mateo and Contra Costa
Counties southward, with much lighter amounts to the north.
Widespread shower activity is expected to shift off to the south
and east of our area by Monday afternoon as the upper low
offshore finally begins to track to the south. Thus, only
scattered shower activity is expected Monday afternoon and
evening. As the low drops south off the Central Coast by late
Monday night and Tuesday, it is forecast to elongate to the
northeast into northern Nevada and then very slowly shift to the
east. Although shower activity will diminish as the week
progresses, enough moisture and instability will remain for shower
chances to remain in the forecast through at least Thursday.
Snow levels are forecast to drop as low as 2500 feet by Monday and
snow accumulation is likely across higher elevations, and
particularly across the southern Diablo Range and Santa Lucia
Mountains where precipitation amounts will be highest.
Temperatures will remain well below normal going into Monday with
highs mostly ranging from the upper 40s to mid 50s and lows mostly
in the upper 30s and 40s. Daytime temperatures are then forecast
to gradually warm from Tuesday through Friday, but nights will
Winds will not be much of a factor going forward, with mainly
light to moderate wind speeds forecast through the week ahead.
Forecast confidence in the longer range has diminished due to
model inconsistencies and disagreement. Yesterday`s model runs
indicated that the next upper low dropping south along the coast
would bring another round of widespread rain as early as Friday.
But the latest models delay rain from that system until Saturday
night or Sunday (ECMWF) or even later (GFS). But the upshot is
that the weather pattern looks to remain unsettled with periodic
rain chances continuing through at least the next 7 to 10 days.
.AVIATION...as of 4:55 PM PDT Sunday...For 00Z TAFs. Breaks in
cloud cover over the North Bay as the main boundary sits over KSFO
extending northeastward to the East Bay Hills. Despite the cloud
cover over the South Bay, extending southward, mostly VFR
conditions. Rain continues around the Bay Area as the system
continues to slowly move southeastward. The chances for
thunderstorms remains low and therefore was kept out of the TAFs.
As the leading edge passes, expect intermittent rain showers
through the TAF period, with another round of rain showers
expected Monday afternoon for the region. Cigs will lower
overnight to MVFR conditions, with isolated terminals seeing bases
drop to 1500 feet. Gusty winds will taper off this evening and
lighten. By tomorrow, the winds will switch around to offshore and
become locally breezy.
Vicinity of KSFO...VFR with rain showers near terminals as the
main front sits right over KSFO at 00z. Ceilings are still
forecast to drop this evening to around 2,500 ft for MVFR
conditions, but will break up and lift tomorrow afternoon. Winds
will remain gusty along the front, but will lighten after it
passes within the hour for KSFO and slightly later for points
east. Winds will be offshore on Monday with locally breezier
SFO Bridge Approach...Scattered varying broken at 2,500 overnight
as cigs lower near terminal with showers in the vicinity.
Monterey Bay Terminals...VFR currently with locally gusty winds
ahead of the front. Cigs are forecast to lower late this evening
as low as 1,500 ft rain showers near, if not over, terminals.
Winds will taper off in the next few hours as the front passes,
with offshore and breezy winds forecast Monday.
.MARINE...As of 8:28 PM PDT Sunday...The weather system producing
all of Sunday`s rain is slowly moving down California coastline.
Breaks in the rain over the northern waters are possible as the
main front is south of San Francisco at this time, though
scattered to widespread showers over the coastal waters through
midweek. Winds have been gusty, particularly near heavy rain, but
as conditions are forecast to gradually improve, the winds will
diminish by late week. The northwest swell will continue and
gradually subside early this week along with a smaller southerly
PUBLIC FORECAST: Dykema
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