Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
1035 PM CDT Wednesday may 22 2013
Short term...(this evening through thursday)
issued at 1219 PM CDT Wednesday may 22 2013
We are finally seeing some progression... albeit grudgingly
slow... in the upper level pattern over the Continental U.S.. the upper low
which has been over our area for many many days is sliding east of
the region... giving was to ridging which will bring fair skies
and dry weather for at least a couple of days. The model guidance
is in good agreement on the arrival of the dry air and seasonably
cool temperature for the next two days... but continues to show
some variation in how things will unfold after that. But... until
then the overall theme will be for the diurnally enhanced precipitation
currently over the area to shift southeast of the area tonight...
allowing for subsidence and much drier conditions to move in from
the northwest as the surface high over central Canada builds into
the region. The upstream dewpoint depressions suggest we shouldn/T
have too much of an issue with development of fog/stratus tonight
once the cloud cover is scoured out... but there is at least some
degree of concern given how much rainfall the area has seen
lately. At this point... it looks like we should hold onto enough
of a gradient and some winds to keep fog limited to patches in low
lying areas near bodies of water... but will be something to keep
an eye on overnight. Thursday should bring mostly sunny skies and
dry weather to the area... with warmer readings than today due to
the sunshine... although they will still be below normal.
Long term...(thursday through tuesday)
issued at 410 am CDT Wednesday may 22 2013
Long term forecast kicks off with a good likelihood for areas of
frost over much of west central Wisconsin by late Thursday night.
Dome of surface 1030mb high pressure Parks itself right over this
region by Friday/12z time frame. Radiational cooling will combine with
cold polar air behind the exiting 500 mb low and mostly clear skies
to produce good swath of temperatures bottoming out into the lower to
middle 30s across much of west central Wisconsin. At this juncture
it appears more likely that a frost advisory may need to be issued
for this region either late tonight or on Thursday. By the way
..the average low temperature for this time of year at eau is
47 degrees. In addition...scattered frost should also occur over far
eastern portions of east central Minnesota tomorrow night.
Short lived 500 mb ridge over Minnesota/WI will begin to erode late Friday
as Pacific northwest storm system treks into the far western
Dakotas. Warm frontal boundary emanating from this system will
overspread much of southern half of Minnesota by late Friday night into
late Saturday morning. This will be catalyst for likely convective
activity over much of western half of forecast area during this time frame.
Both gfs40 and European have supporting solutions for this initial
wave of activity. European continues to trend toward keeping much
of the northeastern portion of Minnesota and west central Wisconsin dry
into early Sunday afternoon. Decided to run with the gfs40 solution due
to its placement of the closed 500 mb low over the Washington/Oregon region
at 18z today...and its current handling of precipitation over our County Warning Area.
With that said scattered showers and thunderstorms will predominate
over the region through the weekend...with a broad area of surface
high pressure poised to infiltrate western sodak by late Saturday
night...but move little into early Monday morning. Strong Theta
east advection anticipated over SW and south central Minnesota Monday
morning...coupled with strong 250mb divergence Couplets...and
moderate low level jet. If things pan out...could be a chance
for isolated to scattered severe storms Sunday evening. Broad surface cyclone
noted above forges into a strong 995mb surface low over western
Kansas by Monday evening. Inverted trough from this system will
be seen through eastern Dakotas into western half of Minnesota Tuesday
through Thursday. Instability associated with this feature demanded
chance probability of precipitation through end of period. Moisture values at least through
next Tuesday should be around 1/2 of amounts experienced with current
storm system. Thus expect another three quarters of an inch to
near one and one half inches Friday night through Tuesday...with
somewhat heavier amounts thereafter. Very early to be sure...but
current analysis portends possible strong cold front punching
through our region next Friday night into Saturday...with decent
potential for more widespread severe weather.
&&
Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1024 PM CDT Wednesday may 22 2013
VFR spreading in fast...with all taf sites VFR at 06z. Some middle
clouds remain dropping in from the north during the night and then
clearing through 12z. May see few cumulus develop over west near
the ridge and further to the southeast during the day...so did
include that. VFR nonetheless...with northeast winds becoming more
east to southeast into Thursday night. May see some gusts over
mainly the eastern sites during the Day. Ridge builds in Thursday
night with light winds and some high clouds moving into the west
late.
Kmsp...VFR conditions during the period. Some middle clouds remaining
early...then some cumulus possible into the day Thursday...dissipating
by evening. Northeast to east winds a bit gusty into the day...then
becoming light southeast by Thursday night.
/Outlook for kmsp/
Friday...VFR. Southeast wind 5 to 10 knots.
Friday night...VFR. Chance of showers. Southeast wind 5 to 15 knots.
Saturday...brief MVFR ceilings possible with a chance of
shra/tsra. Southeast wind 10 to 20 knots.
Saturday night...MVFR ceilings and visibilities possible with a
chance of shra/tsra. Southeast wind 10 to 20 knots.
Sunday...MVFR ceilings and visibilities possible with a chance of
shra/tsra...brief IFR conditions possible. Southeast wind 10 to 20
knots.
&&
$$
Short term...trh
long term...Arizona
aviation...Delaware
