Area forecast discussion
National Weather Service Hastings NE
1220 PM CDT Monday may 20 2013
Short term...(today and tonight)
issued at 415 am CDT Monday may 20 2013
The upper level low across the northern plains this morning will
continue to meander to our north over the next 24 hours...with a few
bands of showers and possibly an isolated thunderstorm rotating
around the low and affecting the local area. Have seen showers
continue to form across western Nebraska early this morning and
affect portions of the outlook area from time to time...with nearly
half an inch of rain falling in Ord since midnight. Expect this
latest band of showers extending from north central Nebraska into
northeastern Colorado early this morning to pivot eastward through
the morning hours...bringing the potential for an additional few
hundredths to maybe a tenth of an inch of rainfall accumulation
through the middle morning hours.
While there may be a break in precipitation for the late morning
through afternoon hours...this break is expected to be fairly short
lived as weak instability will then build across the eastern
portions of the forecast area by early afternoon...ahead of a weak
cold front...which should lead to some additional shower and
thunderstorm development. Even so...overall instability will be
weak...and no severe weather is expected. Winds will also be
noticeably breezy this afternoon...as the pressure gradient
tightens on the backside of the main surface low to our northeast
and good mixing is realized.
For tonight...expect the potential for showers to diminish behind the
passing cold front as the atmosphere stabilizes...however with the
presence of the surface low just to our north...cannot rule out
additional isolated shower activity...and kept some small probability of precipitation in
the forecast through most of the overnight hours.
Long term...(tuesday through sunday)
issued at 415 am CDT Monday may 20 2013
An unsettled week ahead with cooler temperatures initially...then
some warming but also increasing shower/storm chances heading into
the Holiday weekend.
Per previous discussions...the first couple days of this forecast
period will be influenced primarily by an upper level low pressure
over the northern Mississippi Valley which is cut off from the flow.
This will result in cooler/below normal temperatures...wrap around
clouds and an occasional shower chance...mainly on Tuesday. Rain
chances are quite small...and non-existent in northern Kansas
really. Sunshine will be most likely over the southwest/southern one
third of the forecast area...with northern reaches battling clouds.
Thursdays upper level weather map says a weak short wave ridge will
push over Central Plains. That will generally keep most of the area
dry for a short while...but not necessarily result in that great of
weather. An east/northeast flow Thursday will backdoor low clouds
into the area...which essentially will be trapped below the ridging
aloft. Little concerned the forecast may be a bit too sunny so to
speak...and on the warm side given the presence of the low clouds.
Fine tuning will be needed as the week progresses in this area.
After Thursday...a broad southerly flow basically overrides the
cooler regime near the surface. A couple of weak waves Cut Through
the upper level flow as a trough digs into the Pacific northwest.
Models remain reasonably consistent with these features causing
shower/thunderstorm development Friday into the weekend. It won't
rain the whole time by any means...but Friday could be pretty damp.
Basically...lots of 30-40 percent chances in there for that period.
Temperatures will slowly rebound to near normal...maybe slightly
above if more sunshine can prevail from time-to-time.
&&
Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1220 PM CDT Monday may 20 2013
Cumulus clouds have formed with the day time heating. As the
day time heating increases the instability...there is a small
chance for some showers with isolated thunderstorms around the
area. Have kept vicinity thunder for a few hours this afternoon
and evening. Expect VFR conditions through the period.
&&
Gid watches/warnings/advisories...
NE...none.
Kansas...none.
&&
$$
Short term...sar
long term...Moritz
aviation...jcb
