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Office: LBF

FXUS63 KLBF 191154
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
654 AM CDT Sun Aug 19 2018

.SHORT TERM...(Today and tonight)
Issued at 358 AM CDT Sun Aug 19 2018

The main forecast challenges through tonight are precipitation and
temperatures. The combination of an upper low over Nebraska and a
deepening surface low pressure over Kansas will keep the area cool
and damp today.

Today... The broad shower/embedded thunder activity over northwest
KS/southwest Neb will continue to slowly lift northward this morning
as scattered storms affect north central Neb. Increased PoP
along/east of Hwy 183 through midday to reflect this trend. West of
Hwy 83, RAP mesoanalysis indicates weak dry air advection H85-92
despite sfc dew point depressions near 0. Break in precip will
probably continue until diurnally driven showers develop later
today, but can't completely rule something out in the meantime. Kept
schc PoP across all areas. Added patchy fog in the Platte River
Valley with light winds and OGA and LBF observing periodic
reductions in visby (down to 5SM). Better lift and diabatic forcing
this afternoon will support at least scattered storms region wide.
CAMS (including HRRR, RAP, SPC HREF) and the NAM nest are in general
agreement with wrap around showers across the forecast area. Bumped
PoP to likely for a short period this afternoon and evening when
precip should be most widespread. With that being said, did adjust
QPF down slightly due to scattered coverage for a good portion of
the event. Not expecting any severe storms as instability is
lackluster, mid level lapse rates are nearly moist adiabatic, and
deep layer shear is very weak. Temperature-wise, nudged highs down a
degree or two toward the middle of guidance. Given considerable
cloudiness, H85 temps around 10C, and brisk northerly flow, highs
will struggle to leave the 60s northwest Neb and lower 70s elsewhere
(about 10-15 degrees below normal). Increased winds as the pressure
gradient tightens invof sfc low and mechanical mixing from the upper
low and showers. Gusts could exceed 30mph across the panhandle and
western Sandhills.

Tonight... The low pressure drifts east toward NE/KS/MO border,
taking the best forcing and moisture convergence with it. Gradually
taper PoP west to east overnight, resulting in dry conditions west
of Hwy 183 by 12z. Dry air entrainment on the backside of the low is
rather impressive, which should lead to clear skies in the
panhandle. Low temps range from the mid 40s along the Pine Ridge to
mid 50s along Hwy 83 corridor to near 60 far north central Neb.
Still looking at breezy conditions across the eastern half of the
forecast area, which will help keep temps on the milder side (along
with continued showers).

.LONG TERM...(Monday through Saturday)
Issued at 358 AM CDT Sun Aug 19 2018

As the low pressure system approaches the Great Lakes Monday, an
upper ridge begins to build over the southern Plains while a sfc
high settles onto the northern Plains. Nebraska starts the week with
northwest flow aloft on the periphery of the high, then a strong
trough swings through the region late week. A sfc low and cold front
accompany the wave.

Subsidence and isentropic downglide will keep Monday dry and the
area relatively cloud-free. The next shot at precip comes early
Tuesday as a weak shortwave traverses the Plains and low level flow
turns southeasterly, gaining the upslope flow component. Not
expecting much in terms of QPF as overall moisture is limited. A
better shot of precip comes Wednesday with stronger fgen in the mid
levels and increased moisture advection around a lee side low in the
TX/OK panhandles. The upper trough and sfc cold front bring the next
round of storms through the area late Thu.

Highs remain well below normal Mon and Tue in the lower 70s as the
H85 high over the northern Plains recycles cool air into the state.
Temps rebound mid to late week as low level flow transitions to
southerly, kicking WAA into full effect. A decent thermal ridge sets
up late week, helping highs reach the upper 80s again.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 635 AM CDT Sun Aug 19 2018

Latest satellite imagery and surface obs shows low stratus with
MVFR ceilings advancing southward across the eastern Panhandle
and northwest NEB, elsewhere a cloud shield covers central NEB
with scattered to broken mid clouds present elsewhere. Latest
radar display shows an area of rain across south central slowly
spreading into north central NEB where showers have been more so
isolated-scattered in nature. Best chances for showers will remain
across north central NEB early today with a break in
precipitation expected elsewhere though there are low-end chances
in place. Scattered showers and thunderstorms are then expected to
develop this afternoon-evening. By mid evening activity is
expected to start decreasing from west to east. Otherwise, MVFR
ceilings will spread south and east across the Sandhills and parts
of southwest NEB today into north central NEB early this evening.
While ceilings will stay sub-VFR overnight across north central
NEB, improvement to ceilings will be gradual from west-east across
western NEB mid evening on becoming VFR as skies clear.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Snively
LONG TERM...Snively
AVIATION...ET



Office: OAX FXUS63 KOAX 191214 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 714 AM CDT Sun Aug 19 2018 .SHORT TERM...(Today through Monday Night) Issued at 310 AM CDT Sun Aug 19 2018 Early morning water vapor imagery and 500mb analysis indicate upper low over the MT/SD/WY border region digging into the northern Plains, and pushing an upper level ridge east of the forecast area. Radar and IR satellite depict colder cloud tops with relatively more vigorous convection making its way through central KS and western OK, with showers and a few spotty storms extending north through central NE, and another area of slightly stronger convection over the Dakotas. Showers and a few embedded thunderstorms will continue to spread east into the forecast area early Sunday morning. Locally heavy rainfall will be possible with this system, especially across parts of far southeast NE and southwest IA where precipitation is enhanced as the surface low moves through Sunday night. Local storm totals could reach over 3" in southeastern portions of the forecast area. Luckily or unluckily, due to recent drought conditions, it is likely that this region should be able to handle a fairly significant rainfall. While a few thunderstorms will be possible Sunday and Monday, sounding profiles and shear vectors do not look sufficient for severe development. Recent model runs have been gradually slowing the passage of this system. For now, expect precipitation will linger across the area through much of the day Monday, before exiting to our east by Monday night. Some gusty winds, around 20-25kts will be possible Monday, as the pressure gradient tightens on the backside of the departing low. .LONG TERM...(Tuesday through Saturday) Issued at 310 AM CDT Sun Aug 19 2018 Dry weather returns Tuesday and prevails through midweek. Northerly flow will keep temperatures seasonably cool, in the mid to upper 70s Tuesday and Wednesday, before warming back into the 80s to end the workweek. Precipitation chances return Thursday night into Friday as an upper trough moves into the Central Plains. Behind that system, it appears as though warmer and generally drier weather is in-store for the weekend. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) Issued at 700 AM CDT Sun Aug 19 2018 Closed upper low pressure system over western South Dakota and Nebraska will move slowly southeast acrosscentral Nebraska into southwest Iowa by 20/12Z. Showers and a few embedded thunderstorms are forecast to occur across the region by mid morning Sunday and continuing into Monday morning. VFR conditions are forecast, however lower cloud ceilings and MVFR conditions are expected at KOFK, KOMA, and KLNK between 09Z and 10Z on Monday. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...KG LONG TERM...KG AVIATION...Smith
Office: GID FXUS63 KGID 191133 AFDGID Area Forecast Discussion National Weather Service Hastings NE 633 AM CDT Sun Aug 19 2018 .SHORT TERM...(Today and tonight) Issued at 358 AM CDT Sun Aug 19 2018 Duration of the rain is primary forecast concern in the short term. Upper air analysis and water vapor imagery showing a negative tilted trough moving off the Rockies and into the Plains. 500mb, 12-hour height falls of 40 meters noted ahead of the trough. Widespread showers and tstms occurring all the way from NDak to Texas. At the surface, low pressure was located over northern SDak with a trough extending south into the middle of our CWA. Dewpoints were in the mid/upper 60s. As of 07Z the pcpn was moving northeast and extended from Gosper to Jewell Co and all points south. A few rogue showers have popped up ahead of the main pcpn shield. Only a few lightning strikes noted at this time in and near our CWA. SPC meso page does show enough instability in the area for convection although not concerned about severe storms as deep layer shear is negligible. Models continue to move the upper low over our CWA by 00Z tonight and then advance it slowly east, placing it near eastern Iowa by Monday evening. Best timing for synoptic forcing over our CWA looks to be through early afternoon today as depicted by the omega values on cross and time height sections. Comparing several of the operational and CAM models, they generate more widespread rain through the early afternoon and then continue this in the eastern CWA into the evening while bringing more wrap around precip into the western CWA. This seems reasonable with the upper low overhead. Some locations could see a break for a few hours between the initial rain and the wrap around precip. Due to the slow nature of this system, the wrap around precip is expected to last into Monday before gradually ending from west to east. Would expect many locations to receive an inch before all is said and done with some places topping 2 inches. Temperatures won't rise much today due to rain and extensive cloud cover. .LONG TERM...(Monday through Saturday) Issued at 358 AM CDT Sun Aug 19 2018 Monday looks to be a raw day with cooler temps, cloudy skies and strong northwest winds. As the upper and surface lows move to our east, a decent pressure gradient sets up over Neb and KS, thus giving us the windy conditions. However, things should then improve for Tuesday with shortwave ridging again in place. For the rest of the workweek, it appears a gradual warm up is in store for the region and we will be close to average highs for this time of year by Friday. It should be dry for the most part although several models continue to advertise a few disturbances moving through between Tue night and Friday morning. && .AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Monday) Issued at 624 AM CDT Sun Aug 19 2018 Widespread area of rain has moved into the terminals and expect off and on chances for much of the forecast period. Both terminals MVFR at the moment, but imagine they will bounce back and forth between VFR/MVFR depending on when heavier bands of showers pass through. Ceilings should lower some after midnight and its possible they could end up IFR late tonight. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Ewald LONG TERM...Ewald AVIATION...Ewald