Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
654 PM CDT sun may 19 2013
Update...
for 00z aviation discussion below
&&
Short term...(this evening through monday)
issued at 345 PM CDT sun may 19 2013
Narrow area of moderate to strong thunderstorms noted on radar
from Twin Cities south into eastern Freeborn County. Hrrr handled
intiation of this activity over far northern Iowa and far south
central Minnesota very well earlier this afternoon...so used same to
help project convection into tonight across much of the County Warning Area.
Used gfs40 Theta-E advection to sort out timing and intensity
of precipitation into Monday afternoon. Throttled back somewhat on
quantitative precipitation forecast values over portion of the forecast area due to slackening pop chances
later tonight and again on Monday. Local WRF model still indicating
very impressive 850mb transport vector convergence over much of
the forecast area late this afternoon into this evening...with slackening values
noted over SW portion of County Warning Area by 06z. With that said anticipate
best chances for any flood potential for remainder of Flash
Flood Watch region will be east of a line...from St cloud to
Hutchinson...to Winnebago. 500 mb low over western Dakotas will
become vertically stacked with surface cyclone by Monday/12z time frame
above southeast sodak. System will retrograde into southeast nodak by early
Monday evening. Best chances for probability of precipitation clearly indicated over
northern half of forecast area Monday afternoon...in association with best
Theta-E advection coupled with position of right rear quadrant related
to 130kt jet core above northern Ontario.
Long term...(monday night through sunday)
issued at 355 PM CDT sun may 19 2013
Brief discussion due to ongoing storms. Stubborn low pressure system
in South Dakota looks like it will drift east...still over Minnesota on
Wednesday. Trough axis swings by to the south early Wednesday...and
have thus ended mention of storms Tuesday night. Will keep mention
of showers Wednesday and Wednesday night. Mostly cloudy and cool weather
expected and have lowered maximum temperatures. Upper low still close enough to
merit keeping a chance of showers into Thursday in the east. Then
upper ridge approaches. Canadian surface high makes a glancing blow
and winds may be light enough Thursday night to allow temperatures to drop
into the upper 30s from Mille Lacs Lake to Rice Lake and Ladysmith.
Some variation in models as to how long the upper ridge will remain
over the area late this week. Some guidance suggests it moving east
quickly enough to bring in another chance of storms Saturday and
Sunday.
&&
Aviation...(for the 00z tafs through 00z Monday evening)
issued at 653 PM CDT sun may 19 2013
Convective complex of showers and thunderstorms will mainly affect
northern/eastern taf sites this evening /kaxn-kstc-Keau/...with
coverage becoming more worthy only of a vicinity mention after
02z. Could be scattered showers and thunderstorms around through
tonight as the upper low rotates into the area. After sunset this
evening however...the strong storms should hold off until diurnal
destabilization occurs after 17z Monday. Looking like another
afternoon with a decent risk of severe thunderstorms. Winds will
primarily be southeasterly through Monday morning...with gusts to
between 20 and 25 kts developing by 17z Monday. The directional
component will become more south-southwesterly Monday afternoon
as the surface low approaches.
Kmsp...
there will be a short break in the shower/thunderstorm activity
through sunset...and then widely scattered showers and
thunderstorms will be possible from around 02z through 09z. After
the nocturnal activity...there should be a break until diurnal
heating aids in thunderstorm development on Monday afternoon. Ceilings
should be mostly VFR with the exception of MVFR in rain showers.
/Outlook for kmsp/
Monday...VFR/MVFR ceilings. Rain showers/thunderstorms and rain likely. S-south-southeast wind 10-15 g 25 kts.
Tuesday...VFR/MVFR ceilings. Rain showers/thunderstorms and rain likely. S-SW wind 5 kts.
Wednesday...VFR/MVFR ceilings. Rain showers likely. NE wind 5-10 kts.
&&
Mpx watches/warnings/advisories...
Minnesota...Flash Flood Watch through Monday evening for mnz041>045-047>053-
057>063-066>070-075>078-084-085-093.
WI...Flash Flood Watch through Monday evening for wiz014>016-023>028.
&&
$$
Short term...ajz
long term...tdk
aviation...ls
