Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Twin Cities/Chanhassen Minnesota
654 PM CDT sun Mar 9 2014
Short term...(this evening through monday)
issued at 340 PM CDT sun Mar 9 2014
The warmest temperatures since a few 40s occurred around middle February
across the region which is in response to a Pacific air mass
riding across the northern plains/upper Midwest this afternoon. It
could have been a lot warmer if the middle/high cloudiness was
less...no snow cover...and the atmosphere mixed up to around 3k.
Where the snow pack was light along the Lee side of the Buffalo
Ridge in wc Minnesota...temperatures managed to rise into the 50s as of 130 PM.
Monday/S temperatures should be similar to today even with more sunshine
as winds shift to the northwest and slightly cooler 95/92h temperatures develop.
Long term...(monday night through sunday)
issued at 340 PM CDT sun Mar 9 2014
Focal Point to this long term forecast is Monday night through Tuesday due to a
1-2 punch of a pair of low pressure centers. One will drop east-southeast from
western Canada...tracking across the central western Canadian provinces into
the southern eastern Canadian provinces Monday into Tuesday...while the second low
pressure center develops over the typical Colorado region and shifts
eastward across the Central Plains through the Ohio Valley into the Middle
Atlantic States Monday night through Wednesday. The first system will drag a cold front
through the upper miss River Valley region during the day on Monday...
putting the cold air in place ahead of the second low pressure
system...which will be responsible for producing precipitation.
Have made little change to the pop scheme for this event...
indicating that far southern Minnesota will have the greatest chance for precipitation
with chances decrg going northward. There is still some variability in both
quantitative precipitation forecast and p-type...which then affects potential snowfall amounts.
Starting with quantitative precipitation forecast...liquid amounts are likely to range 0.10-0.20
in far southern Minnesota and dropping off going north. Taking this in the context
of p-type...there looks to be less warmer air enveloped into this
system. Have been able to eliminate -fzra/-ip as p-types since
there does not appear to be a definitive deep warm layer nor Bona
fide freezing temperatures at the surface at the time of precipitation. In other
words...the entire blyr column down to the surface looks to be fairly
uniform from above and below freezing...making the only p-types
-ra...-sn...or a mix of only those two. Am looking for precipitation to
start out as a -ra/-sn mix before changing over to all -sn...
making the most intense timing for precipitation around 12z Tuesday to be all
-sn...before the precipitation slackens off during the day on Tuesday and
transitions back to -ra before ending late Tuesday afternoon. Because of
the variations in temperature...this will affect snow ratios...
and latest model consensus puts ratios in the 8:1 to 12:1 area...
making for 1-2" near the Iowa border and less going north of wet
accumulation. However...because of the tight dynamics potentially
coming out of this system...a narrow band of higher accumulations
may well develop with this system over far southern Minnesota. Will need to
see how more mesoscale models develop this idea before jumping on
Once this conglomerate system shifts off to the east by late Tuesday...
the forecast becomes much more tranquil and another warming trend will
take hold. Cold air advection will continue into Wednesday with highs again the 30s as
high pressure moves across. As this high pressure area shifts off to the east
late Wednesday...ridging aloft will move over the central Continental U.S....
leading to a noticeable increases in temperatures for the latter
portion of the week. Highs will again climb into the 40s for the
bulk of the mpx County warning forecast area...along with some lower 50s possible in far southern
and southwestern Minnesota.
Along with the rising temperatures throughout this week will be a
noticeable loss in the snowpack. Except for Tuesday and Wednesday with the
cloud cover and subsequent cold air advection...snow loss each day
this week will average about 1 inch per day. Difficult to say how
this will play into hydrologic concerns...especially with the
overall lack of precipitation. However...the warmer air may lead
to the breaking of ice on many area rivers and this may lead to
potential flooding concerns going forward.
Aviation...(for the 00z tafs through 00z Monday evening)
issued at 624 PM CDT sun Mar 9 2014
Rather stagnant weather pattern for the next 24 hours with west
winds of 5 to 12 kts and broken to overcast high cloud cover. No
precipitation is expected.
Kmsp...no significant concerns other than wind direction and speed
for runway configuration. Pretty confident southwest winds of
5-8kt will back to west-northwest and increase to around 10 knots by middle morning
/Outlook for kmsp/
Tuesday...MVFR ceilings/visibilities possible in -sn. Northwest wind 5-15 knots.
Wednesday...VFR. Northwest wind 5-7 kts becoming west.
Thursday...VFR. West wind 5-10 kts becoming SW.