Area forecast discussion
National Weather Service Grand Forks ND
620 PM CDT Tuesday Jun 18 2013
Update...
issued at 620 PM CDT Tuesday Jun 18 2013
The only change will be to add the aviation discussion. The
forecast is in good shape...with a quiet night in store for the
region. Will take a closer look at temperatures with later updates...but
no major revisions planned.
&&
Short term...(this evening through Wednesday night)
issued at 325 PM CDT Tuesday Jun 18 2013
Forecast challenge will be temperatures and convective potential
from midweek after. Models continue with subtle differences and
will hang with general blend of GFS/ECMWF/Gem solutions as NAM
continues to be quickest in ejecting Pacific northwest upper low eastward.
Surface high will continue to shift across Great Lakes overnight
maintaining modest warm advection and return flow. This should
keep temperatures a few degrees warmer than last night.
For Wednesday upper low will shift into the Pacific northwest. As is does
low pressure deepens across northern High Plains. Ahead of the low
increasing southeast flow will begin to advect deeper moisture N-NW. Moist
axis becomes oriented from Central Plains northwest into the low over
eastern Montana. This moist axis would appear to be the favored area
for convection during the day. Farther east over our forecast area low level
moisture does increase along with a broad area of warm advection
but low/middle level forcing seems limited so did not make any great
changes to probability of precipitation but overall confidence in potential is low. Leaned
towards warmer guidance values based on warming column and solar
potential.
After initial capping feel complex will initiate late evening
vicinity surface low over NE Montana/northwest ND and propagate generally NE into
Canada. Majority of models coming into better alignment in
developing east-west oriented boundary along ND international border
area. This boundary could be focus for some eastward propagating
convection so increased probability of precipitation along the border area late Wednesday
night.
Long term...(thursday through tuesday)
issued at 325 PM CDT Tuesday Jun 18 2013
Uncertainty even greater on Thursday. Airmass to become increasing
unstable across entire forecast area. Low level forcing and favorable
convective potential still looks across the north near quasi-
stationary east-west boundary but where this actually sets up will
determine where brunt of convection will be. If this position
turns out complex will develop across the north propagating east-southeast
during the evening along thickness gradient.
Will maintain chance probability of precipitation through Friday however could be another
active day but models quite spread on solutions. Column will be
quite warm Thursday into Friday with degree of cloud cover
governing just how warm/humid we get.
For Friday night through Tuesday the region will generally be in a
transition period. Friday night into Sat night will still be dominated
by southwest flow aloft. Looks like the best chances for precipitation may be
Friday night with some sort of convective complex forming over the area
and tracking to the east. Models then close off a 500mb low over the
western High Plains Sunday and slowly lift it northeast into Ontario
Monday which would keep some scattered precipitation chances around. As the low
passes off to the east more zonal flow returns by Tuesday. As for temperatures
they look to remain a little above normal with highs in the 80s.
&&
Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 620 PM CDT Tuesday Jun 18 2013
VFR conditions expected with southerly winds increasing on
Wednesday. Diurnal high based cumulus should dissipate this
evening after sunset...and could develop once again on Wednesday once
convective temperatures around 80 are reached.
&&
Fgf watches/warnings/advisories...
ND...none.
Minnesota...none.
&&
$$
Update...dk
short term...voelker
long term...godon/voelker
aviation...dk
