Flood Potential Outlook
Issued by NWS Hastings, NE

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Probabilistic Hydrologic Outlook
National Weather Service Hastings NE
500 PM CST Thu Feb 16 2017

...Spring Flood and Water Resources Outlook Number 1...

This outlook is for the Hastings Hydrologic Service Area (HSA). In
South Central Nebraska this outlook includes the
Platte...Loup...Little Blue...and Republican Rivers and their
tributaries. In North Central Kansas...the Solomon River and its
tributaries are included.

...The potential for spring flooding is near normal on the Platte
River and slightly below normal for most other rivers across south
central Nebraska...

...The potential for spring flooding across north central
Kansas is near to slightly above normal...


...Short Term Hydrologic Outlook...February 16th - March 2nd...

Flooding is unlikely through March 2nd with very minimal if
any chance of flooding through this period.

We have no snow cover currently present. The ice has already melted
off of area rivers likely ending our threat of ice jam flooding for
the season. The ground has thawed and will be able to effectively
absorb precipitation given our currently near normal soil moisture
levels. We are expecting a higher likelihood of above normal
precipitation through the end of February. However, we more than
likely should be able to handle the typical late February storm
system be it rain or snow with little if any threat of flooding.


...Long Term Hydrologic Outlook...March 3rd Through June 15th...

The potential for spring flooding varies from near to slightly above
average over the Solomon River Basin of north central Kansas, to
near average for the Platte River across south central Nebraska, to
slightly below average for most of the other river basins across
south central Nebraska.

South Central Nebraska Spring Flood Outlook:

Antecedent conditions including a generally dry summer and fall of
2016 across south central Nebraska along with an absence of any
strong climate indicators resulting in a spring precipitation
outlook of equal chances, leads us to a below normal possibility of
spring flooding for most Nebraska rivers except for the Platte
River. However, it is important to note that flooding can not be
ruled out even in dry or normal rainfall years as it only takes one
heavy rainfall event to create localized Flash Flooding.

The Platte River is a bit of an exception as it`s headwaters
originate high in the mountains of Colorado and Wyoming where
conditions are currently more favorable for spring flooding than for
rivers originating in Nebraska. The current mountain snowpack in the
Platte River Basin is currently running above normal from 119% to
145% of normal. The largest reservoirs in the upper Platte Basin are
for the most part as full or fuller than in 2016 and are also fuller
than historical averages. This may again result in higher flows this
year making it easier for flooding should we end up seeing
significant spring rains. However, unlike last year where the spring
precipitation outlook was for more likely above normal spring
rainfall in the Platte Basin, this year we are seeing equal chances
and consequently more uncertainty on how we will end up regarding
spring rains. Putting it all together we have the favorable mountain
conditions for high spring runoff in the Platte Basin, but have been
abnormally dry along our stretch of the Platte River in south
central Nebraska as noted by the drought monitor. These factors in a
sense lead us to a near normal probability of spring flooding for
the Platte River and much will depend on how much rain we ultimately
receive this spring. The peak time for high flows on the Platte
River from mountain snowmelt generally runs from late May through
early June. Therefore, this will be the timeframe needing to be
watched most closely on the Platte River to see if it coincides with
any abnormally heavy rainfall events.

North Central Kansas Spring Flood Outlook:

As a hold over from last year`s heavier rains across north central
Kansas there is a near to slightly above average chance of spring
flooding across the Solomon River Basin. However, there is also much
uncertainty given the lack of clear climate signals regarding
expected spring precipitation amounts as noted by the equal chances
spring precipitation outlook.


...Climatological Review (2016 and More Recent Precipitation
Trends)...

Let`s start with a look back at precipitation totals for the year
2016 across the 30 county NWS Hastings coverage area (24 counties in
Nebraska and 6 in Kansas):

In the most basic sense, 2016 precipitation across the 30-county
area as whole would best be described as relatively "near-normal".
More specifically, the majority of locations observed annual totals
between 85-125 percent of the official 30-year normal. In other
words, for most places, 2016 as a whole was not overly-dry or overly-
wet. That being said, there were some localized drier and wetter
exceptions, and the summer season in particular did exhibit more
variability/extremes than the year as a whole (see state-specific
summary below for more details).

Now here is a closer look at 2016 precipitation totals/trends within
both Nebraska/Kansas portions of the local area (including a
precipitation table below):

Central/South Central Nebraska (24 Counties):
Most of the local area measured annual precipitation totals between
85-125 percent (or generally 2-5") of the 30-year normal. From a
purely statistical standpoint, this means that most of the area was
relatively near-normal. However, when digging deeper, there was some
distinct and somewhat odd geographical variability. For one, the
driest portions of the area really seemed to focus within central
counties, including the Tri Cities and nearby areas. In contrast,
some of the highest annual totals tended to focus around the "outer
fringes" of the area, farthest from the Tri Cities. Based on data
from around 40 official NWS Cooperative Observer stations, a few of
the driest sites in 2016 included Minden with 19.96" (6.26" below
normal) and Hastings airport with 20.66" (6.45" below normal). In
contrast, a few of the wettest local Nebraska stations featured
Shelby (3 miles NE) with 33.07" (6.21" above normal) and Ord airport
with 30.62" (5.68" above normal). Although the year as a whole did
not appear overly "extreme" for most places, the meteorological
summer season in particular (June-August) was notably dry especially
within central counties, putting stress on crops during the peak
growing season. Highlighting the notable summer dryness included
Minden, which had its 2nd-driest summer on record with only 3.29"
(30 percent of normal), and Grand Island airport, which had its 6th-
driest summer on record with only 4.72" (44 percent of normal).
Please refer to the table below for 2016 totals for dozens of other
official stations.

North Central Kansas (6 Counties):
Compared to Nebraska portions of the area, this portion of North
Central Kansas exhibited more uniformity with modestly wetter-than-
normal annual precipitation totals, as nearly all places measured
between 110-145 percent of 30-year normals. In fact, several
stations recorded one of their Top-10 wettest years on record.
Unlike many of the Nebraska counties farther north, even the summer
months featured near-to-above normal rainfall. Based on data from
around 18 official NWS Cooperative Observer stations, a few of the
very-wettest sites in 2016 featured Natoma with 36.41" (10.92" above
normal) and Plainville (4 miles WNW) with 36.20" (10.77" above
normal). In contrast, one of the drier (but still slightly above
normal) stations included Phillipsburg with 25.93" (0.51" above
normal).

2016 Drought recap (entire NWS Hastings coverage area):
The year started out with no drought categories whatsoever
within the 30-county area, according to weekly drought updates by
the U.S. Drought Monitor. However, during mainly the latter half of
the year, some modest degradation took place especially within
central portions of the Nebraska coverage area, mainly in response
to the notably drier-than-normal summer months mentioned above. From
August onward, at least a small area of Severe Drought (category D2)
became focused primarily within Kearney County (the "epicenter" of
summer dryness). Extending slightly outward from Kearney County to
include at least portions of several nearby counties was an area of
Moderate Drought (category D1). While not considered "true drought",
a broader zone of "Abnormally Dry" (category D0) conditions
enveloped most counties along/west of the Highway 281 corridor at
year`s end.

The first table below features precipitation totals and departures
from normal/percent of normal for the entire year of 2016, with data
depicted for 31 locations scattered throughout the local area. Most
of these stations are NWS Cooperative Observers, along with a few
primary airport sites:


  Location          Precip                            Percent of
North Central KS  All of 2016     Normal   Departure    Normal
--------           --------       ------   ---------  --------
Alton 2SW           33.37         26.13      +7.24       128
Beloit              35.35         27.92      +7.43       127
Jewell              32.73         26.82      +5.91       122
Logan               29.54         22.73      +6.81       130
Natoma              36.41         26.29     +10.12       138
Phillipsburg        25.93         25.42      +0.51       102
Plainville 4WNW     36.20         25.43     +10.77       142
Smith Center        32.61         25.71      +6.90       127


  Location          Precip                            Percent of
South Central NE  All of 2016     Normal   Departure    Normal
--------           --------       ------   ---------  --------
Aurora 4N           25.82         30.96      -5.14        83
Cambridge           22.73         22.49      +0.24       101
Clay Center         24.56         28.78      -4.22        85
Elwood 8S           20.93         23.43      -2.50        89
Franklin            23.93         26.23      -2.30        91
Genoa 2W            28.30         28.82      -0.52        98
Geneva              27.85         29.27      -1.42        95
Gothenburg          27.65         23.71      +3.94       117
Grand Island Arpt   24.23         26.66      -2.43        91
Greeley             21.52         26.91      -5.39        80
Hastings Airport    20.66         27.11      -6.45        76
Holdrege            26.81         27.00      -0.19        99
Hebron              31.86         31.39      +0.47       101
Kearney Airport     21.87         25.23      -3.36        87
Lexington 6SSE      26.37         23.44      +2.93       113
Loup City           26.78         27.09      -0.31        99
Minden              19.96         26.22      -6.26        76
Ord Airport         30.62         24.94      +5.68       123
Osceola             27.96         28.89      -0.93        97
Ravenna             26.29         26.54      -0.25        99
Shelby 3NE          33.07         26.86      +6.21       123
St. Paul            27.86         26.21      +1.65       106
York 3N             30.33         30.23      +0.10       100


Now that we`ve examined precipitation trends/totals for the entire
year 2016, it`s time to take a closer look at more recent
precipitation trends over the past few months, specifically what has
transpired since the start of "meteorological winter" back on Dec.
1st (meteorological winter is defined as the three calendar months
of Dec-Jan-Feb).

As evidenced in the data presented in the table below (and supported
by NWS AHPS precipitation analysis), this winter-so-far has featured
at least slightly-above-normal precipitation. More specifically, the
majority of the local 30-county area has observed 95-150 percent of
normal precipitation since Dec. 1st. Interestingly, the majority of
this winter precipitation has fallen in the form of liquid rain and
not snow! In fact, as of this writing, Grand Island has measured
merely 4.8" of snow so far this season (14.6" below normal) and is
on pace to have one of the least-snowy winters on record! For much
of the area, the single-biggest precipitation episode so far this
winter consisted of a freezing rain/icing event on Jan. 15-16.
Although this storm resulted in at least minor damage to power
infrastructure and trees due to ice accrual, it brought beneficial
and widespread precipitation of generally 0.50-1.50". Earlier in the
winter, Christmas Day featured a rare round of winter thunderstorms
with brief, soaking rainfall, and even damaging winds and tornadoes!
Although this winter as a whole has featured above normal
precipitation, it is worth noting that in terms of very recent
trends, these first few weeks of February have been very dry (with
the main exception of extreme northern local counties such as
Valley/Greeley which have been near-normal). Keeping things in
perspective though, one must keep in mind that no matter how much
precipitation falls during the winter, it usually only accounts for
a small percentage of total annual precipitation, the vast majority
of which falls during the spring and summer.

This next table below highlights precipitation totals and departures
from normal/percent of normal for meteorological winter thus far,
covering Dec. 1 - Feb. 14. This table features data for 29 locations
scattered throughout the local area, many of which are the same as
found in the 2016 annual table above. Most of these stations are
official NWS Cooperative Observers, along with a few primary airport
sites:


  Location          Precip                            Percent of
North Central KS  Dec 1-Feb 14    Normal   Departure    Normal
--------           --------       ------   ---------  --------
Alton 2SW            2.78          1.78      +1.00       156
Beloit               2.47          1.90      +0.57       130
Jewell               2.28          1.90      +0.38       120
Natoma               2.03          1.98      +0.05       103
Phillipsburg         1.92          1.49      +0.43       129
Plainville 4WNW      1.66          1.75      -0.09        95
Smith Center         2.02          1.44      +0.58       140


  Location          Precip                            Percent of
South Central NE  Dec 1-Feb 14    Normal   Departure     Normal
--------           --------       ------   ---------  --------
Aurora 4N            2.10          1.84      +0.26       114
Cambridge            1.74          1.31      +0.43       133
Clay Center          2.49          1.63      +0.86       153
Elwood 8S            1.41          1.40      +0.01       101
Franklin             2.19          1.55      +0.64       141
Geneva               2.45          1.61      +0.84       152
Grand Island Arpt    1.91          1.50      +0.41       127
Greeley              1.37          1.55      -0.18        88
Hastings Airport     1.47          1.26      +0.21       117
Hebron               2.46          2.05      +0.41       120
Holdrege             1.84          1.36      +0.48       135
Kearney Airport      1.88          1.33      +0.55       141
Lexington 6SSE       1.48          1.10      +0.38       135
Loup City            1.56          1.59      -0.03        98
Minden               1.38          1.23      +0.15       112
Ord Airport          1.82          1.18      +0.64       154
Osceola              2.29          1.89      +0.40       121
Ravenna              1.34          1.37      -0.03        98
Shelby 3NE           2.33          1.68      +0.65       139
Superior             1.61          1.95      -0.34        83
St. Paul             1.95          1.31      +0.64       149
York 3N              2.37          2.31      +0.06       103


...Weather/Climatological Outlook For The Next Week Through The Next
Three Months...

It`s now time to switch gears and look ahead to expected weather
conditions over the next several days and expected climate trends
over the next several months:

Starting with the most immediate local weather expectations over the
next week (through Feb. 23): According to the latest NWS Hastings 7-
day forecast, a remarkably mild and fairly inactive/dry weather
pattern should prevail. Precipitation-wise, there are relatively
small chances for rain showers on Sunday night into Monday (Feb.
20), and next Thursday (Feb. 23) could feature the beginning stages
of a potentially more widespread precipitation event, although
forecast uncertainty is still high with this being a week away.
Temperature-wise, confidence is high that the ongoing notably-mild
stretch will continue, with daily high temperatures mainly in the
60s and overnight lows mainly in the 30s, before a possible cool-
down to more winter-like values returns late next week. Putting this
ongoing warmth in perspective, 30-year normal highs during the
latter part of February typically average somewhere in the low-mid
40s across most of South Central Nebraska/North Central Kansas.

Looking out a bit farther into the final week of February, the
latest 8-14 day outlook from the Climate Prediction Center (valid
Feb. 23-March 1) at least slightly favors a continued above-normal
temperature regime (33-50 percent chance) and also slightly favors
above normal precipitation (33-40 percent chance).

Looking ahead to the upcoming month of March as a whole, the latest
one-month outlook from the Climate Prediction Center (CPC) released
Feb. 16 favors "equal chances" of seeing above, near or below normal
temperatures during the month, and also calls for "equal chances" of
seeing above, near or below normal precipitation. This "equal
chances" forecast means there is no clear signal in current longer-
term forecasts to support one of these outcomes over another (above
normal, near normal, below normal). However, as a point of
reference, normal March precipitation across the local area ranges
from around 1.40" in the western-most counties (such as
Dawson/Furnas), up to around 2.10" in far eastern counties along and
near Highway 81 (such as York/Thayer). Temperature-wise, long-term
30-year normals (based on 1981-2010 data) indicate that March high
temperatures across South Central Nebraska and North Central Kansas
gradually climb from averages in the mid-40s/near-50 early in the
month to the upper 50s/low 60s by month`s end. Average daily low
temperatures in March gradually increase from around 20 to around 30
degrees.

Turning to the meteorological spring months of March-April-May as a
whole, the overall climate pattern is expected to be defined by ENSO-
neutral conditions, as the weak La Nina pattern of earlier this
winter has abated. Not surprisingly given the transition to ENSO-
neutral, the latest CPC three-month outlook valid for March-May and
released on Feb. 16 shows no strong signals for either above or
below normal precipitation for this spring, but it does slightly
favor above normal temperatures. More specifically, most of the
local Nebraska area has a small tilt toward above normal
temperatures (33-40 percent chance), while north central Kansas is
assigned slightly higher probabilities (40-50 percent) of above
normal readings. As for precipitation, the entire local area is
assigned equal chances of measuring above, near or below normal
values. Again, this means that long range forecast tools just do not
present enough of a signal to support one of these possible outcomes
over another. Despite the current lack of predictability regarding
how the upcoming spring as a whole might turn out, one can keep in
mind that 30-year normal precipitation from March-May across the NWS
Hastings coverage area typically ranges from 7-10 inches, with the
lowest amounts generally west of Highway 183 and highest amounts
near the Highway 81 corridor.

Finally, the latest U.S. Seasonal Drought Outlook issued by CPC on
Feb. 16 and valid through the end of May indicates that the small,
localized area of Moderate Drought (category D1) currently indicated
in the Kearney County area is expected to improve. For the rest of
the local area, there are currently no expectations of drought
development through May.

(The longer range forecasts issued by CPC and referenced in the
preceding paragraphs are based on output from various forecast
models, as well as forecaster expertise, and take into consideration
ongoing global/tropical atmospheric and oceanic states, recent
trends in observed data, soil moisture conditions, etc. More
information about these longer-range forecasts can be obtained from
the CPC web site at: http://www.cpc.ncep.noaa.gov)


...Future Outlooks...

The next spring probabilistic outlook is currently scheduled to be
issued Thursday, March 2nd.

&&

Visit our local NWS office website for current weather/hydrological
and climate information for South Central Nebraska and North Central
Kansas at:
www.weather.gov/hastings

Additional climate information for the region can be obtained at:
www.hprcc.unl.edu

Additional information on climatological outlooks can be found at:
www.cpc.ncep.noaa.gov

Further information on drought conditions can be obtained at:
www.drought.gov
www.drought.unl.edu
www.droughtmonitor.unl.edu

Information on mountain snowpack can be found at:
www.wcc.nrcs.usda.gov/ftpref/downloads/wsf/201702wsfwww.pdf
www.wcc.nrcs.usda.gov

NWS AHPS precipitation analysis maps can be found at:
http://water.weather.gov

National snow analysis page can be found at:
www.nohrsc.noaa.gov/nsa

Soil Moisture:
www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Soilmst/Soilmst.
shtml

Reservoir Levels:
www.usbr.gov/gp/hydromet/curres_google.htm

For training on NWS probabilistic graphics:
www.youtube.com/watch?v=pSoEgvsnpv4

For training on NWS river forecast graphics:
www.youtube.com/watch?v=psIByj8EZY0

$$

Wesely/Pfannkuch



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