Area forecast discussion
National Weather Service Grand Forks ND
133 PM CDT Tuesday may 21 2013
Update...
issued at 131 PM CDT Tuesday may 21 2013
Precipitation winding down....thankfully just in time as areas from west
of Grafton up to Walhalla cannot stand another drop. Highest
report was 9.5 inches of rain from this storm 2e6n Milton ND.
Will continue to tweek probability of precipitation.
&&
Short term...(today through wednesday)
issued at 344 am CDT Tuesday may 21 2013
Precipitation continues to be the main concern throughout the period.
WV loop has the upper low continuing to rotate over South Dakota...and the
center of the low should continue to drop very slowly southward
throughout the day today. The surface low will also move further south
and the tight pressure gradient over the northwestern County Warning Area will
begin to relax by afternoon. Will maintain the Wind Advisory
through 15z and think that winds will diminish below criteria by
late morning. Precipitation will continue to rotate through County Warning Area on the
north side of the upper low from east to west. Coverage is a bit
more scattered but most locations will again get wet at some point
today. Continued the trend of high probability of precipitation mainly in the southern
counties today with diminishing probabilities in the north
throughout the day.
The upper low will move further off to the southeast tonight and
into Wednesday. High pressure will begin to build in from Canada.
Continued to have decreasing probability of precipitation through tonight and into
tomorrow...with only a 30 percent chance hanging on in the
southern counties by Wednesday afternoon. There could be even some
clearing in the northern counties Wednesday afternoon...so kept
higher temperatures in the middle to upper 60s in that area with lower
readings further south where clouds and precipitation will hang around
longer.
Long term...(wednesday night through monday)
issued at 344 am CDT Tuesday may 21 2013
The upper trough will move off into the Great Lakes Wednesday
night...with surface high pressure building further south into the
plains. Clearing skies will allow lows to drop to around 40
Wednesday night...but there should be some good recovery on
Thursday as temperatures warm back up into the 60s to around 70.
Southeasterly winds will pick back up Thursday night and keep
temperatures a few degrees higher as a trough of low pressure gets going
over the northern rockies. Conditions will be dry through Thursday
night.
Friday-Monday...the surface ridge will begin to move eastward on Friday
as the upper ridge begins to flatten across the northern plains. The
flow will transition to more zonal or southwest by the weekend with
persistent longwave troughing over the west and a series of impulses
ejecting eastward into the plains from the upper trough to the west.
This will result in at least chances for scattered showers or storms
through the weekend. However...confidence in timing these impulses
is low at this range. Temperatures generally are expected to be near
or a few degrees below normal.
&&
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 131 PM CDT Tuesday may 21 2013
IFR/low MVFR ceilings will persist at all taf sites through the
afternoon...but do expect a very slow clearing from north to south
for northern taf sites after 02 UTC. Persistent rain showers have
become spotty...but may become a bit more widespread later this
afternoon and evening at kbji/kfar before moving out of the region
by Wednesday morning. Northeast wind will persist...gusting at times
this afternoon to 25 kts.
&&
Hydrology...
issued at 344 am CDT Tuesday may 21 2013
Rain showers will continue today across the Red River basin and
associated tributaries. Additional rainfall is generally expected
to remain around a quarter to a third of an inch or less. River
flood warnings remain in effect at Walhalla and Neche along the
Pembina river. Walhalla appears to have leveled off somewhat in
moderate flood stage...but will have to continue to be monitored.
Neche continues to rise quite rapidly towards major flood stage.
River flood warnings have also been issued for the Forest River at
Minto and the Park River at Grafton...where stages may reach minor
flood stage.
Over the last 18 hours...one inch to one and one quarter inch of
rain fell over Buffalo River basin and the Red River basin in the
vicinity of Wahpeton. This has resulted in new forecasts pushing the
crest into minor flood stage. With some uncertainty on how much rain
will fall over the next 24 hours...will issue flood watches for
these Three Points.
Areal flooding remains a concern...especially across
Walsh...Pembina...and parts of Cavalier counties...where some of the
heavier rainfall totals have occurred. Increasingly saturated ground
may lead to some overland flood concerns with additional showers
today across other areas of the region.
The Flash Flood Watch remains in effect for parts of Pembina County
as heavy rainfall over the past few days has caused floodwaters to
approach the top of the spillway at the Renwick dam. River levels
continue to rise along The Tongue river at Akra. See the Flash Flood
Watch product for further details.
&&
Fgf watches/warnings/advisories...
ND...Flash Flood Watch through Wednesday afternoon for ndz008.
Minnesota...none.
&&
$$
Update...Riddle
short term...Jr
long term...makowski
aviation...Rogers
hydrology...makowski
