Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
1041 PM CDT sun may 19 2013
Update...
for 06z 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 06z tafs through 06z Monday night)
issued at 1042 PM CDT sun may 19 2013
The area of showers and thunderstorms over southeastern Minnesota and
west central WI will gradually fill back in to the north and west
across central Minnesota overnight...which is illustrated by the hrrr
model. MVFR ceilings/visibilities in the rain showers are expected...along with IFR
ceilings from kstc-kaxn. After 15z Monday...expect a lull in
convection until daytime heating causes the next round of
potentially strong to severe thunderstorms to develop. Winds will
be southeasterly at or below 10 kts overnight...then become gusty by late
morning Monday and veer slightly to more south/southwesterly in
direction.
Kmsp...
expect the showers over southeastern Minnesota to gradually expand back
west/northwest at the start of the period...then taper off by 14z
Monday when winds become gusty. Ceilings may dip to 1500 feet overnight
with the shower activity...but the prevalent ceiling should be
2500-3500ft. Southeast winds around 150 degrees begin gusting to
25 kts by 15z...then veer to around 200 degrees by 18z with gusts
continuing.
/Outlook for kmsp/
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.
Thursday...VFR. NE winds 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
