Area forecast discussion
National Weather Service Omaha/valley NE
630 am CDT Tuesday may 21 2013
Aviation...
12z tafs for koma...klnk...kofk.
Clouds will continue to move down across the area as moisture
wraps around the middle level low pressure system over the northern
plains. Some MVFR ceilings will occur this morning...especially
at kofk. Ceilings should rise a bit this afternoon at klnk and
koma as some heating occurs...but ceilings at kofk will likely
remain in the MVFR category. Tonight...ceilings will be on the
decrease...dropping to MVFR at koma and klnk. Some IFR ceilings Arkansas
possible at kofk...mainly after 06z. Some occasional -shra may
also occur at kofk through the period...but chances were not high
enough to mention in the taf for now.
Miller
&&
Previous discussion... /issued 323 am CDT Tuesday may 21 2013/
Discussion...
quiet weather across the area this morning as upper low spins
nearby. Subjective 00z upper air analysis indicates broad upper low
centered in northeast South Dakota/southeast ND...with upper-level ridge from
northern California through central Saskatchewan. Upper-level jet streak up to 95kt
extended from Texas/OK panhandles to northwest MO. Deep 850mb low was
centered in eastern ND/northwest Minnesota...with trailing cold front
through central Nebraska/central Kansas/western OK...and warm front extending
from low across northern Minnesota/northern WI/up of Michigan. 850mb dewpoints
of 8c+ covered the broad area ahead of the fronts...with drier air
also into Nebraska/IA/northeast Kansas/northwest MO. Surface low at 07z was
centered in northeast South Dakota...with trailing cold front along the MO
River Valley.
Main forecast concerns include potential for showers in the
northeast County Warning Area tonight/Wednesday...then thunderstorm potential Friday
through Monday night. Forecast soundings indicate more stability
today than yesterday...and think County Warning Area will avoid showers during the
day...though clouds will increase. May see a shower skirt the
northeast County Warning Area tonight as upper low drops out of the Dakotas toward
northwest Iowa...but think soundings still look too stable for
thunder...and have kept precipitation mention limited to showers.
Wednesday night and Thursday look quiet as upper low moves slowly
eastward...with middle- to upper-level ridging moving into the Central
Plains. Temperatures will remain on the cooler side through Thursday...but
as southerly flow returns to the area Friday...temperatures will
moderate to near or above normal.
While upper-level ridging is expected to linger over the central US
through the weekend...a middle-level warm front is prognosticated to develop
across the area on Saturday. European model (ecmwf) forecast indicates front would then
sag southward on Sunday...while GFS hints at front lifting north.
Warm air advection on Friday afternoon/evening could be enough to
kick up some showers/thunderstorms...with additional showers/storms
along the front on Saturday. Would expect a dry period or two as
front slips southward out of the area...with thunderstorm activity
focusing on the High Plains as well as in a corridor along the
front. Model blends have sprayed the entire extended period with
chance probability of precipitation...but have tried to pull back to slight chance in
periods that look less favorable for showers/storms. Uncertainty
increases for Monday/Tuesday...as best forcing for storms still
looks to remain west of here...but ridge begins to weaken and waves
move through the ridging.
Mayes
&&
Oax watches/warnings/advisories...
NE...none.
Iowa...none.
&&
$$
