Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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066
FXUS63 KOAX 260441
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1141 PM CDT Thu May 25 2017

.SHORT TERM...(Tonight through Sunday)
Issued at 245 PM CDT Thu May 25 2017

The primary forecast concerns are precipitation chances Tonight,
then from Friday night through Saturday.

Impressive mid tropospheric closed low (535 dm at 500 mb) was over
southern Saskatchewan this morning. That feature should track
northeast tonight, then wobble southeast toward Lake Superior by
Sunday evening. 12 hour height falls of 50-100 meters were noted
on the east side of the low, and also extended southwest toward
California. Surface analysis at 19z showed a cold front across the
Dakotas that extended down into central Nebraska and then back
into eastern Colorado. Some showers have been occurring over parts
of the local area, and may continue into the evening. Highest
chances though are later tonight, when storms may roll in from the
west. Combination of several weak features, including that cold
front pushing through, will result in small chances for showers
and thunderstorms overnight. For now, expect that it will be dry
on Friday from mid morning through the evening. Look for lows
tonight to be mainly in the 50s. Highs Friday should be mainly
upper 70s and lower 80s, with some mid 70s possible in the far
northwest part of the forecast area.

Models are in pretty good agreement that showers and storms will
develop to our west Friday evening, and then move east. Model
timing is a little variable but will keep some low POPs going
Friday night in parts of eastern Nebraska, but keep western Iowa
and the far eastern fringes of Nebraska dry. Increased POPs a bit
from the previous forecast for Saturday, especially through mid
afternoon. Strongest large scale forcing for ascent are during the
day Saturday. The 12z GFS and NAM are similar with timing, but the
ECMWF and Canadian models are about 3-6 hours slower. Kept a low
POP going into the evening, but based on current expected timing,
it would be mainly out of our area. Clouds and precipitation
should keep highs mainly 65 to 75. On Sunday, we will have a
northwest breeze, but deeper mixing, so look for highs in the
lower and mid 70s north to mid/upper 70s south.

.LONG TERM...(Sunday night through Thursday)
Issued at 245 PM CDT Thu May 25 2017

Closed low at 500 mb will initially be around or north of Lake
Superior, with a ridge from the far western CONUS up into the
Yukon and Northwest Territories. The result will be cool-ish
northwest flow that should decrease as the pattern deamplifies
and heights rise over the Central Plains.

Have kept rain chances below 15 percent (starting late Saturday
night) through Tuesday evening. Then we have chances mainly 20
to 30 percent from Tuesday night into Thursday. Models do differ
though on which 6 hour periods have the best chances though.

Highs should be mainly in the 70s, with lows in the upper 40s to
mid 50s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1135 PM CDT Thu May 25 2017

Conditions are generally expected to remain VFR through the
period, however a few showers and thunderstorms could impact the
TAF sites between 06Z and 12Z. The best chance for precipitation
appears to be at KLNK and KOMA at this time. Otherwise, southerly
winds will swing around to the north Friday morning as a cold
front moves through.


&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Miller
LONG TERM...Miller
AVIATION...KG



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