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FXUS63 KLBF 161438
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
938 AM CDT Sun Jun 16 2019

.UPDATE...
Issued at 938 AM CDT Sun Jun 16 2019

The latest update is account for the on going showers across
northwest Nebraska and the eastern Panhandle. Rainfall amounts
are generally a tenth of an inch per hour or less, but the KLNX
radar estimates it could be as high as a quarter of an inch per
hour over eastern Sheridan and far western Cherry Counties. This
morning convection should set up a boundary which additional convection
across SW NEB will develop or intensify later this afternoon.
Several CAMs and the incoming 12Z NAM are highlighting southwest
Nebraska for heavy rainfall and a marginal risk of severe weather.
We increased rainfall amounts in this area which serves our
current flood watch well.

UPDATE Issued at 613 AM CDT Sun Jun 16 2019

A forecast update is in place for the showers which are farther
south than forecast by the HRRR and RAP models.

UPDATE Issued at 429 AM CDT Sun Jun 16 2019

The HRRR, RAP and NAM continue to indicate heavy rain tonight (1.5
to 4 inches). A Flood Watch is in place late this afternoon
through Monday morning for the southern Sandhills and parts of
southwest Nebraska.

&&

.SHORT TERM...(Today through Monday)
Issued at 327 AM CDT Sun Jun 16 2019

An upper level disturbance across Wyoming moves into nwrn Nebraska
this morning and casts a weak Sfc front across the Sandhills and
Southwest Nebraska this afternoon. The front is expected to become
the focus for thunderstorms and locally heavy rainfall late this
afternoon and this evening with the best rain chance across the
Sandhills.

The model consensus shows the front and the rain shifting slowing
south and east late tonight and decays Monday morning across ncntl
Nebraska.

If the model consensus is correct, a sfc front will reform across
the Sandhills and swrn Nebraska Monday afternoon. Once again the
front will be the focus for locally heavy rainfall late Monday
afternoon.

The rain forecast today, tonight and Monday uses a blend of the
HRRR, RAP, HREF and the model blend. The NAM was not used as it
places the heavier rain south of the model consensus including the
SREF which keeps the heaviest rain across the cntl Sandhills this
afternoon and tonight. The temperature forecast today through
Monday uses the guidance blend plus bias correction which worked
well Friday and Saturday.

.LONG TERM...(Monday night through Saturday)
Issued at 327 AM CDT Sun Jun 16 2019

The model consensus suggests the best rain chances Monday night are
along and south of Interstate 80. A check on moisture advection in
the NAM and other models indicates weak winds around 15-20kts at
h850 and 700mb, and 15-25kts at h500mb. This will support slow
moving ordinary thunderstorms that are outflow dominant. Ambient
precipitable water of 1.25-1.4 inches supports a low or marginal
risk for flooding given the weak moisture advection shown by the
models.

The models continue to show a mostly closed h700mb low forming
across srn Nebraska Tuesday. This supports a continue chance of
showers and thunderstorms across wrn and ncntl Nebraska with the
best chance for heavy rain across eastern Nebraska, east of the
h700mb low.

The model consensus is in good agreement for 500mb winds to increase
to 40-50kts Wednesday through Saturday. The instability however
remains very modest with MLCAPE generally less than 2000J/KG. High
temperatures in the upper 70s to around 80 produce very little
instability. Thus, there are opportunities for a few strong or
isolated severe storms late Friday and Saturday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 625 AM CDT Sun Jun 16 2019

VFR conditions are expected to continue through the forecast
period. Light rain showers near KAIA and KTIF will slowly push
southeast this morning but direct impacts to TAF sites are not
expected so will limit to VCSH for now. Watching for development
of scattered thunderstorms between 16/20-22z generally in vicinity
of KOGA. Confidence is highest in impacts to KLBF with perhaps
brief MVFR restrictions under any storm. Will defer to later
forecast to address as confidence increases. More widespread low
CIGs arrives towards end of period and persist well into Monday.

&&

.HYDROLOGY...
Issued at 938 AM CDT Sun Jun 16 2019

The latest CAMs with support from the 12z operational NAM continue
to highlight the potential of a 1-4" of rainfall centered over
southwest Nebraska. We are a bit concerned that this rain may
center slightly northeast over the central Sandhills where the
water table is abnormally high. Given that it is still early and
the latest guidance is rolling in now, we are not going to make
any major changes to the flood watch that was issued this
morning, but are evaluating the need to expand it northeast.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 4 PM CDT /3 PM MDT/ this afternoon through
Monday morning for NEZ023-024-035-036-057>059-069-070.

&&

$$

UPDATE...Jacobs
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Jurgensen
HYDROLOGY...Jacobs
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