Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/07/17
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
915 PM CDT Thu Apr 6 2017
Issued at 256 PM CDT Thu Apr 6 2017
H5 analysis from earlier this morning had a closed low
over south central lower Michigan. a trough of low pressure extended
south of this feature to the Florida Gulf Coast. A secondary,
embedded shortwave was noted across western Iowa and showed up
nicely on WV imagery this afternoon. West of the trough and
shortwave, a ridge of high pressure extended from southern Utah,
north northeast into northern Manitoba. East of the upper low and
trough, a ridge of high pressure extended north from Bermuda into
the Canadian Maritimes. West of the western CONUS ridge, a trough of
low pressure extended from the Gulf of Alaska south into the western
Pacific-off the coast of northern California. At the surface, high
pressure dominated the weather pattern across the Dakotas into
central Nebraska earlier this morning. Winds were light earlier this
morning, and have begun to shift to the south as high pressure
pushes east into the eastern Dakotas and eastern Nebraska this
afternoon. Readings as of 3 PM CDT ranged from 52 at O`Neill, to 62
.SHORT TERM...(This evening through Friday)
Issued at 256 PM CDT Thu Apr 6 2017
Tonight and Friday: Near term forecast challenges are
temperatures and winds on Friday. For tonight: Surface high pressure
will push east into the mid Mississippi valley overnight. Southerly
winds will begin to increase as this feature exits to the east, and
should be in the 5 to 15 MPH range overnight. The addition of
southerly winds and warm air advection behind a warm front, will
give a boost to lows tonight over what was seen earlier this
morning. Overnight lows will generally be in the middle to upper
30s, with the warmest readings across the northwest and sandhills,
where winds are expected to be strongest across the forecast area.
On Friday, southerly winds will increase by afternoon to 20 to 30
MPH with gusts appg 35 MPH in the afternoon. The latest NAM and GFS
solutions do indicate good unidirectional winds to 825 MB tomorrow
afternoon. Mixing to that level, yields lower 70s for North Platte
Friday afternoon. The inherited forecast had a high of 70 for North
Platte and felt this to be too cool based on the latest met and mav
guidance which had 74 for a high at North Platte for Friday. That
being said, will give a 2 to 4 degree boost to temps for Friday.
.LONG TERM...(Friday night through Thursday)
Issued at 256 PM CDT Thu Apr 6 2017
Mid term: Friday night through Sunday: Precipitation chances
Saturday night into Sunday is the main forecast concern.
Temperatures will continue their climb Friday night into Saturday as
very warm H85 air pushes into western and north central Nebraska.
After mild lows in the middle 40s Friday night, highs will surge
into the upper 70s and lower 80s for Saturday. With readings rising
into the 80s on Saturday and a dry airmass in place, minimum
relative humidity will fall off to around 20 percent Saturday
afternoon. Fortunately a surface trough of low pressure is expected
to be anchored across western then central Nebraska on Saturday.
Winds INVOF this feature will be light saturday afternoon and will
help to alleviate the fire weather threat. A cold front will
approach, then track through western and north central Nebraska
Saturday night. The frontal passage will largely be uneventful and
will be mainly a wind shift. Late Saturday night into Sunday
morning, elevated instability will lift into the western forecast
area overnight. H800 LI`s become negative by late evening and the
model even generates some light convective precipitation in the
north overnight. That being said, introduced a mention of isolated
thunder in the forecast.
Extended: Sunday night through Thursday: In the extended,
precipitation chances Sunday night into Wednesday are the main
forecast challenges. For Sunday night into Monday: An upper level
trough of low pressure will lift across the northern Rockies
emerging onto the high plains Sunday evening. The ECMWF and GFS
solutions this morning have come into much better agreement with
their track of this feature early next week. In fact, they are in
good agreement this morning. That is, the models track the H500 low
across southern South Dakota. On this track, the bulk of rain will
fall across South Dakota into far northern Nebraska. With this in
mind, pops were scaled back in the south and confined to the north.
This resulted in some decent changes to the ongoing forecast. Benign
conditions will set in Monday night with a second wave of low
pressure to arrive Tuesday night into Wednesday. With this second
system, moisture works its way into central and western Nebraska and
have introduced thunderstorms in the forecast from Wednesday into
Wednesday evening based on moisture return and negative LI`s as
indicated in the latest GFS soln.
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 616 PM CDT Thu Apr 6 2017
VFR is expected all areas tonight through Sunday afternoon.
A southerly nocturnal low level jet increases to near 50kt
tonight. Low level wind shear is expected in many areas.
Otherwise scattered high level clouds are expected from a storm
system affecting the Wrn U.S..
Issued at 914 PM CDT Thu Apr 6 2017
A blend of the HRRR models...the 1 hour GFS output and the RAP
places critical fire weather conditions Friday across Zone
204...the Eastern Panhandle. Per coordination with WFO CYS...a
fire weather watch has been issued for this area.
Fire Weather Watch from Friday afternoon through Friday evening
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
635 PM CDT Thu Apr 6 2017
302 PM CDT
Short term concerns center on winds, high waves, and lakeshore
Bottom line up front: Wind advisories have been canceled, the
lakeshore flood warning for Illinois has been canceled, we have
maintained the high wind warning and lake shore flood warnings for
Indiana. Widespread flooding is not expected across Illinois, but
do expect minor flooding to be possible right at the lake shore.
The deep and mature upper level circulation over Lake Erie will
slowly move up through New England into Friday. The surface low,
while still strengthening, will also pull east through the period
as well. Meanwhile, surface high pressure across the upper
Midwest, while not overly strong, will maintain a decent gradient
across the area through this evening, especially across the lake.
Winds across the Illinois side of Lake Michigan largely have held
a NW direction which has minimized the build up of waves along the
Illinois lakefront, though there is a mesoscale boundary draped
across Cook County which is maintaining a NE component at times.
Winds with this NE shift are not super strong, and therefore while
minor flooding right at the immediate lake shore in Illinois is
possible, did not feel a flood warning served the situation well.
The story is different across NW indiana where NW winds have been
able to build waves along the Indiana shoreline. RAP forecasts
suggests a few hour period still today where winds can strengthen,
thus the high wind warnings and lakeshore flood warnings remain in
effect. This is not the time to be at the shore.
On the back side of the circulation a well developed cumulus field
will continue through sunset. Hi resolution guidance paints a few
showers this afternoon, and thus maintained a low mention though
coverage of this should remain low.
High pressure will slowly nose in from the west through the night,
and thus expect a gradual clearing to the skies. Forecast
soundings suggest some decoupling to the winds, and thus expect
winds to subside, though the may hang on a bit longer in Indiana
and in the urban areas. Temperatures will fall to at or around the
freezing mark tonight.
On Friday the high pressure ridge will shift from Iowa at daybreak to
western/central Illinois in the afternoon. Clear skies and
weakening winds will be the story, along with a warm up back into
Friday night through Thursday...
218 pm...Main forecast concerns include frost potential Friday
night...warm up for the weekend and next chance of showers and
thunderstorms Sunday night through Monday night.
A ridge of high pressure will move across the area Friday evening
and with generally clear skies and light winds...some patchy frost
is possible...especially across the southeast half or so of the
cwa. Temperatures slowly begin to warm aloft overnight along with
increasing high/mid clouds...so confidence on how widespread the
frost becomes is low. Maintained frost mention in the grids/zfp
but some tweaks/changes are possible with later forecasts.
Breezy southerly winds will develop Saturday and continue on
Sunday as high temps will warm well into the 60s on Saturday and
into the lower...perhaps mid 70s on Sunday. Wind directions should
prevent a lake breeze with the warmer temps all the way to the
Low pressure will move across the north central plains Sunday into
Sunday night and eventually to the northern Great Lakes region by
Monday night. Models appear to be converging on a solution with an
upper wave moving across the area Sunday night and this looks to
be the best chance of showers and a few thunderstorms. For now
have stayed dry Sunday and after this wave moves through...much of
Monday could be dry with a second wave possibly allowing
additional showers and thunderstorms to develop Monday afternoon
into Monday evening. Confidence is still rather low regarding how
this system evolves but trends do seem to be emerging. High temps
on Monday likely to still be mild...at least in the 60s and
possibly higher depending clouds/morning precip.
Another ridge of high pressure will move across the area midweek
with another system moving across the region Wednesday night into
Thursday. This timing is faster than previously shown from the
models so confidence on this system/timing is also low. cms
For the 00Z TAFs...
Only aviation forecast challenge this TAF cycle is winds. Lake
breeze moved through ORD/MDW late in the afternoon, but with time
lake influence should wane this evening and winds trend back to
west of due north. Timing of the switch to west of due north of
low confidence. Gustiness should abate this evening, though an
occasional gust up to 20kt is possible tonight into Friday
morning, gustiness should be the exception, not the rule. As
northwest winds begin to ease Friday afternoon it should allow
for the development of a lake breeze, which will likely result in
a wind shift to northeast late in the afternoon.
320 pm...Strong low pressure over Pennsylvania will move northeast
across New England tonight and into Quebec Sunday. At the same
time...high pressure extending from southern Canada to the central
plains will move southeast tonight into Friday...eventually
reaching the Gulf of Mexico coast. The gradient will remain strong
between these two systems...but slowly begin to weaken overnight
into Friday morning. Gales will slowly end from north to south
late tonight into Friday morning. A weaker ridge will extend
north from the high and will move across the lake Friday
afternoon into Friday evening with a period of light winds which
will shift southerly Saturday and begin to increase with speeds
possibly increasing to 30 kt. These southerly winds will shift
southwesterly as low pressure moves from the central plains Sunday
to the northern lakes region Monday. After this low passes...a
cold front will likely shift winds northerly Tuesday into Tuesday
IN...Lakeshore Flood Warning...INZ001-INZ002 until 1 AM Friday.
LM...Gale Warning...IL nearshore waters until 5 AM Friday.
Gale Warning...LMZ743-LMZ744-LMZ745-LMZ777-LMZ779 until 10 AM
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