Area forecast discussion
National Weather Service Grand Forks ND
111 PM CDT Monday may 20 2013
Update...
issued at 104 PM CDT Monday may 20 2013
Upper low and surface low over far northeast South Dakota at midday
with widespread rain over the forecast area. A break in the rain now
over north central Minnesota (or at least a lessening) and that will move
in this afternoon from the east. Rain amounts over the area heaviest
Cavalier-Pembina County region with isolated 4-6 eastern Cavalier-west
Pembina and north central Walsh counties where areal flood
warnings in effect.
Lowered temperatures all areas a bit today with minimal rise expected.
Wind gusts to 40 kts still Hallock area and winds in excess of
wind advection still in northeast ND so will leave that alone.
&&
Short term...(today through tuesday)
issued at 339 am CDT Monday may 20 2013
Precipitation and winds will be the main forecast concern for the short
term.
The upper low centered over South Dakota will continue to wobble over the
region through the early part of the work week. Bands of showers
and a few thunderstorms will continue to move northwestward
through the County Warning Area as the low rotates to our southeast. Another inch
to inch and a half of rain will be possible in some areas through
today with more expected tomorrow. Exact placement of heaviest
rainfall is still somewhat uncertain...but at this point the
northern counties seem that they could see the most as models show
the 700mb deformation band pivoting over the area. There have
been some reports of some overland flooding in western Pembina
County...so issued an areal Flood Advisory for that region. Some
locations have received enough rainfall the past few days that
additional accumulations could create overland flood problems in
areas where there has not been time to soak in. On the other
hand...the heaviest rainfall has been very spotty and some
locations have only had half an inch or so. Due to the spotty
nature of the rain that has occurred will hold off on any areal
flood watches for the time being.
The surface low will be centered over the southern Red River valley
through much of the day today...with the models showing some
slight differences in exact placement. There will be a tight
pressure gradient over our northwestern counties through much of
the day. GFS has some winds near 50 kts at 900mb that could mix
down and make kdvl area very gusty...but the NAM is not nearly as
strong. Sites have fallen below advisory criteria...but think that
the northwestern counties will pick up again later on this morning
as the surface low heads east and the gradient tightens a bit. Will
keep the Wind Advisory going for now and have extended it a bit
into this evening as it may take a bit for winds to die off.
The upper low and surface low will it will sink further to the south
tonight into Tuesday. Precipitation will continue to rotate into the County Warning Area
through Tuesday afternoon. Kept very high probability of precipitation going for tonight
into Tuesday with another half an inch or so of accumulation
possible in some areas.
Long term...(tuesday night through sunday)
issued at 339 am CDT Monday may 20 2013
The upper low will finally begin to move off to the east Tuesday
night. There could still be some precipitation bands at least over our
southern counties so kept probability of precipitation likely through Wednesday morning in
that area with lesser amounts further north. There will be some
lingering clouds and chance for precipitation into Wednesday over the
south which will keep temperatures below 60...while the north will see
more sun and get a bit warmer. The drying and clearing trend will
continue into Wednesday night.
Thursday-Sunday...dry and pleasant conditions are expected for
Thursday and Friday as a surface ridge noses into the northern plains.
The 00z GFS/European model (ecmwf) are in decent agreement for next weekend with the
middle/upper ridge axis shifting slowly east into the upper Midwest and
a longwave trough over the west. As the upper flow becomes more
southwesterly across the High Plains next weekend...chances for
showers and thunderstorms may begin to increase over the area. Temperatures
are expected to remain near seasonal averages through the period.
&&
Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 104 PM CDT Monday may 20 2013
The highest wind speeds should be at kdvl but kgfk/ktvf will still
see some pretty gusty east-NE winds. Kbji and kfar will be quite a
bit lower for wind speeds due to their closer proximity to the surface
low. Exact visibilities and ceilings tough to call but it definitely looks
wet. Will stick with steady rain at all taf sites even though there
may be some temporary breaks. Cloud heights seem to be increasing a
little this afternoon but they should go down again tonight.
&&
Hydrology...
issued at 339 am CDT Monday may 20 2013
A river Flood Warning has been issued for the Pembina river at
Walhalla. Runoff from the rainfall over the past few days has
resulted in river levels rising into minor flood stage. The
Pembina river at Neche is forecast to rise into major flood stage
early this week. However...some uncertainty exists with these
forecasts based on future precipitation as well as placement and
magnitude of rainfall over the past few days.
Also issued a Flood Advisory for western Pembina County...with some
reports of overland flooding near mountain ND. The potential for
additional overland flooding will need to be monitored.
Otherwise...given the recent rain and the potential for another 1 to
2 inches of rainfall over the next few days...several river forecast
points along the mainstem red and surrounding tributaries may reach
flood stage. River flood watches remain in effect for sites that may
rise above flood stage. Some uncertainty exists in these
forecasts...and the river responses will depend on future rainfall
amounts and placement...as well as how much of the rainfall runs off.
&&
Fgf watches/warnings/advisories...
ND...Flood Watch through Tuesday evening for ndz006>008-014>016-024-
026>030-038-039-049-052>054.
Wind Advisory until 1 am CDT Tuesday for ndz006>008-014-015-054.
Minnesota...Flood Watch through Tuesday evening for mnz001>009-013>017-
022>024-027>032-040.
Wind Advisory until 1 am CDT Tuesday for mnz004.
&&
$$
Update...Riddle
short term...Jr
long term...makowski
aviation...godon
hydrology...makowski
