Area forecast discussion
National Weather Service Grand Forks ND
1251 PM CDT Sat may 25 2013
Update...
issued at 1239 PM CDT Sat may 25 2013
Cumulus field developed over solar areas as expected but beginning to
thin out some allowing for more middle/late afternoon sun. Based
on current trends raised maximum temperatures a few degrees most areas.
Exception is over northwest forecast area where stratus has been slow to lift and
need to lower maximum values a few degrees there. Otherwise a few
adjustments to cloud cover and rest is good.
Update issued at 943 am CDT Sat may 25 2013
Minimal changes for this update. Some clearing across southeast ND as far
east as southern valley however with convective temperatures in
the middle 60s and a shallow moist layer will likely see cumulus to some
degree develop. Otherwise St and fog across northwest forecast area beginning to
lift. Overall expect pc-mcldy skies today. Temperatures on track
so no changes.
Update issued at 641 am CDT Sat may 25 2013
Added a patchy fog mention across the Devils Lake area this
morning as a few locations are reported some reduced visibilities
mostly 4 to 6 miles with the exception of Langdon which is down to
one mile. Good mixing will make for a short duration this morning.
No other changes this morning to todays forecast.
&&
Short term...(today through sunday)
issued at 345 am CDT Sat may 25 2013
Challenge today will be temperatures and clouds with convection tonight.
Models in fair agreement with the short term and used a blend for
this forecast. Persistent southwest flow through the forecast
period will keep active shower...tstorm pattern continuing.
Challenge with the short wave energies will be placement and the
time of day with potential to tap a more unstable airmass if wave
passage coincides with peak heating.
Currently moderate warm air advection likely still producing
scattered shower activity across Minnesota lakes and trees though
radar trend shows decreasing coverage may just be artifact of
overshooting as the echos drift farther from the kmvx radar.
295k isentropic surface forecast shows the movement of the saturated
layer aligned with the radar echos. Weak ascent wanes by late
morning and have slight chance probability of precipitation ending at 18z.
Attention then turns to the west where the next round of convection
will struggle eastward from central ND. Showalters stay positive
for much of the night County warning forecast area wide. Kept any pop mention to the SW
half of the County warning forecast area through Sunday 12z...though think even less of
the area will see shower activity...with the shower chances slowing
moving east Sunday afternoon.
Long term...(sunday night through friday)
issued at 345 am CDT Sat may 25 2013
Sunday night to Monday night...increasing probability of precipitation into the likely
category across the southern Red River with combination of 500mb
shortwave energy atop 850mb convergence. 00z Gem and GFS a bit
faster and a touch farther north than 00z European model (ecmwf) but fairly similar
signals for the area. Negative showalters with 200 to 400 j/kg of mu
cape expected as surface low tracks across the southern County warning forecast area Monday
morning. Convection will continue to move to the east northeast
and amount of temperature recovery will depend on speed of shortwave and
subsidence in its wake. Highs in the 60s where the clouds linger
the longest and 70s in the west most likely.
Tuesday-Friday...models in good agreement indicating southwest flow
aloft and then an upper low closing off somewhere in the vicinity of
the forecast area toward the end of the period. This is an active pattern...not
that dissimilar from the last heavy rain event. There are still a
lot of details with low confidence (like where the upper low closes
off...and how quickly it then propagates to the east)...but this
will be something to keep a close eye on.
&&
Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 1239 PM CDT Sat may 25 2013
IFR ceilings have lifted out of kdvl...eastward progress has been limited
to kgfk and brief period of MVFR there. Looking at low VFR ceilings
through this taf period as main moisture stays well west of region
for the time being. Gusty wind character should abate by sunset...as
direction stays southeast everywhere. Not much if any precipitation
expected through Sunday morning...reflected in dry tafs.
&&
Hydrology...
issued at 1240 PM CDT Sat may 25 2013
All tributaries to the Red River are falling across the forecast
area. The exception is the Buffalo River at Dilworth which is
nearing its forecast crest of 12.8 feet.
On the main Stem of the Red River...the river is steady or falling
in the southern part of the valley. And in the northern valley...the
Red River is rising as a respectable amount of water continues to
flow into the mainstem red. Oslo is nearing its crest of 26.0 feet...
Drayton is forecast to crest Tuesday morning...and Pembina is
forecast to crest next Thursday morning.
River flood warnings were cancelled for the South Branch Buffalo
River at Sabin and the Pembina river at Neche. River flood warnings
remain in effect at Pembina...Drayton and Oslo on the mainstem
red...as well as Hallock...Grafton and Dilworth.
Areal flood warnings remain in effect for Pembina...Walsh...and
eastern Cavalier counties and will likely be extended this afternoon
due to overland flooding. Water levels across this area should
gradually decrease over the next few days with modest additional
rainfall anticipated.
A Flash Flood Watch remains in effect through Sunday afternoon for
areas downstream of the Renwick dam on The Tongue river. Water
remains very high at the dam site and is being held back by a
constructed earthen levee on top of the dam structure. At this
time...officials note the temporary levee on top of the Renwick dam
remains stable and will still be monitored. Otherwise...Lake Renwick
has been slowly receding the last couple of days.
&&
Fgf watches/warnings/advisories...
ND...Flash Flood Watch through Sunday afternoon for ndz008.
Minnesota...none.
&&
$$
Update...voelker
short term...jk
long term...tg
aviation...wjb
hydrology...Rogers
