701
FXUS63 KOAX 180426
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1126 PM CDT THU SEP 17 2020
..UPDATED FOR 06Z AVIATION FORECAST DISCUSSION
DISCUSSION
ISSUED AT 319 PM CDT THU SEP 17 2020
FORECAST SUMMARY:
A CONTINUATION OF RELATIVELY TRANQUIL WEATHER IS IN THE FORECAST FOR
THE NEXT WEEK. GRADUALLY WARMING TEMPERATURES WILL TAKE US THROUGH
THE END OF SUMMER AND PAST THE AUTUMNAL EQUINOX ON TUESDAY.
PRECIPITATION CHANCES WILL BE SPOTTY AT BEST.
TONIGHT THROUGH THURSDAY:
MAIN UPPER AIR PATTERN FEATURES A DEEP TROUGH TO OUR EAST, EXTENDING
FROM HUDSON BAY INTO THE EASTERN CONUS, WHICH IS FORECAST TO DEEPEN
FRIDAY BEFORE LIFTING NORTHEAST. TO OUR WEST, ANOTHER UPPER
LOW/TROUGH WAS MOVING TOWARD THE PACIFIC NORTHWEST, AND IS EXPECTED
TO SWING THROUGH THE NORTHERN ROCKIES AND INTO THE NORTHERN PLAINS
THIS WEEKEND. IN BETWEEN, WE'LL SEE ONE MORE DAY UNDER THE INFLUENCE
OF THE EASTERN TROUGH BEFORE HEIGHTS BEGIN TO RISE FOR THE WEEKEND
AHEAD OF APPROACHING WESTERN TROUGH.
THAT TROUGH WILL MOST LIKELY AFFECT OUT WEATHER SOMETIME SUNDAY INTO
SUNDAY NIGHT WHEN SHORTWAVE EXTENDING SOUTH THROUGH THE WESTERN
DAKOTAS INTO WESTERN NEBRASKA PIVOTS NORTHEAST. ASSOCIATED SURFACE
FRONTAL SYSTEM IS STILL ADVERTISED BY CONSENSUS MODEL OUTPUT TO
REMAIN JUST WEST OF OUR AREA, KEEPING MAINLY SOUTHERLY LOW LEVEL
FLOW IN PLACE. HOWEVER MID LEVEL WARM ADVECTION/LIFT MAY BE ENOUGH
TO OVERCOME RELATIVELY DRY ATMOSPHERE TO PRODUCE A FEW SHOWERS
SUNDAY OR SUNDAY NIGHT. OTHERWISE PRECIPITATION CHANCES WILL BE HARD
TO COME BY THROUGH THE MIDDLE OF NEXT WEEK.
TEMPERATURES ON FRIDAY SHOULD HOLD IN THE LOWER 70S MOST AREAS AS
COOLER AIRMASS REMAINS OVERHEAD. MODERATELY THICK SMOKE LAYER ALOFT
IS FORECAST TO REMAIN OVER THE AREA AT LEAST INTO SATURDAY AS MID
LEVEL FLOW TAKES SMOKE NORTH FROM THE WESTERN STATES THEN SOUTHEAST
INTO THE PLAINS. WHEN SMOKE LAYER HAS BEEN THICKEST WE HAVE SEEN
TEMPERATURES LEVELING OFF IN THE HEAT OF THE DAY WITH HIGHS
AVERAGING SEVERAL DEGREES LOWER THE CONSENSUS MODEL OUTPUT. WOULD
EXPECT THAT SAME SCENARIO FRIDAY AND SATURDAY GIVEN HRRR-SMOKE MODEL
OUTPUT. HOWEVER UPWARD TREND OF TEMPERATURES STILL PUTS HIGHS BACK
INTO THE MID TO UPPER 70S SATURDAY BEFORE WARMING FURTHER INTO THE
MIDDLE 80S BY TUESDAY AND WEDNESDAY OF NEXT WEEK. CONFIDENCE ON
AREAL EXTENT AND THICKNESS OF SMOKE LAYER LOWERS SIGNIFICANTLY AS WE
GET PAST 48 HOURS OF THE FORECAST, SO WILL HAVE TO BE CONSIDERED
WITH EACH PACKAGE. IF INFLUENCE IS STILL INTACT NEXT WEEK, EXPECT
HIGHS TO BE SEVERAL DEGREES COOLER.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1130 PM CDT THU SEP 17 2020
CLOUDS WITH BASES FL050 TO FL100 WILL BE POSSIBLE OVERNIGHT AND
INTO AT LEAST LATE FRIDAY MORNING. AMOUNTS WILL VARY FROM SCT TO
BKN. SOME PATCHY FOG IS POSSIBLE LATE TONIGHT, BUT OTHERWISE
EXPECT VFR CONDITIONS. SMOKE ALOFT IS UP TO AS HIGH AS FL200, BUT
ABOVE THAT THERE IS NOT MUCH SMOKE. WINDS WILL BE UNDER 10 KNOTS
OVERNIGHT, AND THEN INCREASE TO AROUND 10 KNOTS OR SO FRIDAY.
WINDS MAY BE A BIT STRONG AT KOFK TOMORROW BY NOON, IN THE 10 TO
15 KNOT RANGE.
OAX WATCHES/WARNINGS/ADVISORIES
NE...NONE.
IA...NONE.
DISCUSSION...DERGAN
AVIATION...MILLER
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