Area forecast discussion
National Weather Service Duluth Minnesota
712 am CDT Monday may 20 2013
Aviation.../12z taf issuance/
widespread showers and thunderstorms will continue across the
Northland today and tonight. Conditions will vary from largely VFR
at khyr...to vlifr at kdlh. Low pressure will continue to rotate
throughout the area.
&&
Previous discussion... /issued 354 am CDT Monday may 20 2013/
Short term...precipitable waters axis has shifted into eastern wisc zones and extends
northwestward into arrowhead. Along this moist plume showers and
a few thunderstorms continue. Quick check with Ashland Colorado sheriffs
indicates earlier flooding has subsided near Ashland. However
given continued rain moving across area next several hours have
extended and expanded slightly the coverage of the Flood Advisory.
Otherwise...fairly quiet across most of County Warning Area except northern Minnesota zones
where 850 mb frontogenesis has weakened according to Storm Prediction Center
mesoanalysis. Very gusty winds occurring as a result of surface
pressure gradient enhanced by Cold Lake and approaching surface low.
Today...surface low will meander near western Minnesota with warm front
stretching east across southern wisc zones. Numerous models suggest a
relative dry slot will advect into southeastern County Warning Area today with a decrease
in frequency of rw/trw. Concern is increasing for svrwx event over
southern tier of County Warning Area roughly from southern Pine County and into northwest
Wisconsin...south of marine boundary. Hi res dlhwrf and hrrr3km
differ on position/movement of surface boundary during the afternoon. Latest
forecast sbcapes increase to 1500 j/kg as boundary layer gets an opportunity
to warm in absence of persistent rain. Surface boundary will provide low
level helicity for any developing convection by afternoon. Main
limiting factor appears to be deep layer bulk shear which is on
the low end of the spectrum required for storm organization. Will
carry Flood Watch for now although it appears that amounts have
been low enough in many areas to limit flood threat. Still have
850 mb moist axis shifting and rotating north into northern Minnesota County Warning Area tonight.
Tonight/tomorrow...sfc/mid level low shifts slowly south as warm
conveyor belt eventually works its way into northern periphery
of synoptic scale circulation. Models suggest that area of
850 mb frontogenesis will remain quite health across northern tier of Minnesota
zones and this may be ultimately where highest totals occur. Any
limited svrwx threat will be suppressed farther south of County Warning Area with
time.
Long term...Tuesday night through Monday.
The large low pressure system will continue to affect the Northland
into the middle of the work week...with showers and a few
thunderstorms likely Tuesday night and into Wednesday. By
Wednesday...the chance of precipitation will decrease dramatically
across the north...while it will decrease across the south Wednesday
night. Dry high pressure will be in full force across the Northland
by Thursday...allowing for a period of drying across the region. The
next chance of precipitation will arrive Saturday night and continue
into the weekend. Not looking for much precipitation with the next
system...so will be going with chance probability of precipitation at this point. It looks
like a bit more substantial precipitation very late in the
period...with a strong low pressure system moving through the plains
by Monday. Temperatures will largely be in the 60s throughout the
entire extended period. The exceptions will be near Lake
Superior...where temperatures will likely be much cooler.
Aviation...06z tafs.
Mainly IFR/LIFR ceilings/visibilities with -ra/-dz and br through the forecast.
The exception will be in the vicinity of thunderstorms and rain when ceilings/visibilities may
improve to VFR. Gusty winds also in the vicinity of thunderstorms and rain.
However...due to uncertainty of timing of thunderstorms and rain...have left out
at this time.
&&
Point temps/pops...
dlh 55 44 52 43 / 80 70 70 70
inl 59 45 56 43 / 80 70 60 40
brd 71 52 62 47 / 80 70 70 60
hyr 78 54 68 46 / 60 70 70 60
asx 67 46 54 42 / 60 70 70 60
&&
Dlh watches/warnings/advisories...
Minnesota...Flash Flood Watch through Tuesday morning for mnz010>012-018>021-
025-026-033>038.
WI...Flash Flood Watch through Tuesday morning for wiz001>004-006>009.
Ls...Small Craft Advisory until 6 am CDT Wednesday for lsz121-140>148.
&&
$$
Short term...Cannon
long term....dap
aviation...dap
