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Lawrenceville Weather

Weather for Longmont, Colorado

Lat: 40.17N, Lon: 105.11W
Wx Zone: COZ043 CWA Used: BOU

Colorado Drought Monitor

The Colorado Drought monitor is a subset of the United States Monitor, issued every Thursday morning, based on drought conditions the previous Tuesday. The map below shows the current drought level around the state, and the percent of Colorado land area in each drought level compared to the previous week.

Read an explanation of the drought intensities and what they mean.

Colorado Drought Monitor

Colorado Hydrologic Information Statement

Note that if drought conditions are not being experienced, or in the case of river flooding or heavy rain, this statement may be used to indicate river flows or flood potential.

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Probabilistic Hydrologic Outlook
National Weather Service Denver/Boulder CO 
400 PM MST Thu Feb 16 2017

...Spring Flood and Water Resources Outlook...

This outlook is for north central and northeast Colorado and 
includes the Colorado...North Platte and South Platte Rivers.

...Flood Outlook Highlights...
* Near average risk of minor snowmelt flooding in the North and 
  South Platte River basins.
* Above average risk of minor snowmelt flooding in the headwaters of 
  the Colorado River in north central Colorado. Areas prone to 
  flooding in the past may experience issues again this year.
* Significant flooding due to mountain snow runoff alone is not 
  likely. However...it is still early in the snow accumulation 
  season and conditions could change before the runoff begins.

Above normal temperatures have melted the snowpack in the lower 
foothills and diminished frozen ground. Near normal subsurface soil 
moisture was observed in north central Colorado with low soil 
moisture in eastern Colorado. This has slightly decreased the risk 
of significant spring snowmelt flooding in the North and South 
Platte River basins. However...mountain snowpack is higher in the 
Colorado River basin leading to a higher than usual spring flood 
potential due to snowmelt west of the Continental Divide.

Above normal future snow accumulations combined with heavy rains and 
rapid melt will increase the current flood potential while below 
normal future precipitation and gradual or intermittent freezing and 
thawing will decrease the magnitude of the current assessment. Near 
average risk suggests that locations which typically experience 
minor spring time flooding may flood again this year and those that 
typically don't will not.

...Current Hydrologic Conditions...
The Colorado River basin snowpack on February 16th was 144 percent 
of normal and had nearly reached the peak normal snowpack (99 
percent of the peak). In a typical year the snowpack is only 69 
percent of the peak snowpack at this time with April 10th being the 
normal peak date as reported by the Natural Resources Conservation 
Service.

The mountain snowpack in the South Platte River basin was 138 
percent of normal and 85 percent of the normal peak snowpack. In a 
typical year the mid-February snowpack is only 61 percent of the 
peak snowpack with the normal peak date being April 27th. 
Therefore...there is still plenty of time remaining for the snowpack 
to rise above the normal peak.

The Laramie and North Platte River basin snowpack on February 16th 
was 130 percent of normal and 82 percent of the normal peak snowpack 
which typically occurs around April 11th.

Liquid water in the mountain snowpack generally ranged form 8 to 40 
inches. Basin reservoir storage continued to hold fairly steady at 
105 percent of average and 73 percent of capacity at the end of 
January. 85 percent of the U.S. Geological Survey stream gages had 
normal to above normal flows in mid-February.

Widespread Moderate Drought /D1/ or Abnormally Dry Conditions /D2/ 
continued to be observed east of the Continental Divide. There were 
no drought designations west of the divide on the February 14th U.S. 
Drought Monitor.

...Climate Summary... 
Precipitation since January 1st has been above normal in the 
mountains and near to below normal at lower elevations. 2017 
temperatures have been near to above normal with the exception of 
the northeast Colorado corner.

...Weather and Drought Outlooks... 
The 30 and 90 day precipitation outlooks and 30 day temperature 
outlook have equal chances of being near...above or below normal. 
The 90 day temperature outlook has a tilt toward above normal 
temperatures. The U.S. Seasonal Drought Outlook valid February 16th 
through May 31st indicates drought conditions persisting east of the 
Continental Divide (D1 or greater on the U.S. Drought Monitor).

...Numerical River Outlooks... 
In Table 1 below, the current (CS) and historical (HS) or normal 
probabilities of exceeding minor...moderate...and major flood stage 
are listed for the valid time period.

CS values indicate the probability of reaching a flood category
based on current conditions.

HS values indicate the probability of reaching a flood category
based on historical or normal conditions.

When the value of CS is greater than HS...the probability of
exceeding that level is higher than normal. When the value of CS is
less than HS...the probability of exceeding that level is lower
than normal.

...Table 1--Probabilities for minor...moderate and major flooding...
                     Valid Period: 2/18/2017 - 5/19/2017
                    
                                       :    Current and Historical
                                       :     Chances of Exceeding
                                       :       Flood Categories
                                       :      as a Percentage (%)
                      Categorical      :
                   Flood Stages (FT)   :   Minor    Moderate   Major
Location           Minor   Mod   Major :  CS   HS   CS   HS   CS   HS
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:South Platte River
South Platte         7.0    9.0   11.0 :  <5   <5   <5   <5   <5   <5
Denver              11.0   12.5   14.0 :  <5   <5   <5   <5   <5   <5
Henderson           10.0   11.0   15.0 :   6    6   <5   <5   <5   <5
Kersey              10.0   11.5   13.0 :   8    9    5    6   <5   <5
Weldona             10.0   11.0   13.0 :   7    8    5    6   <5   <5
Balzac              10.0   11.0   13.0 :   8    8    5    6   <5   <5
Julesburg           10.0   11.0   12.0 :  <5    5   <5   <5   <5   <5
:Plum Creek
Sedalia              8.0   10.0   12.0 :  <5   <5   <5   <5   <5   <5
:Bear Creek
Morrison             9.0   10.0   11.0 :  <5   <5   <5   <5   <5   <5
Sheridan             8.0   10.0   11.0 :  <5   <5   <5   <5   <5   <5
:Clear Creek
Golden              10.0   13.0   14.0 :  <5   <5   <5   <5   <5   <5
Derby                9.0   10.5   11.5 :  <5   <5   <5   <5   <5   <5
:N Fk Big Thompson River
Drake                6.0    7.0    8.0 :  <5   <5   <5   <5   <5   <5
:Cache la Poudre River
Fort Collins 9NW     7.5    9.0   10.5 :  <5   <5   <5   <5   <5   <5
Fort Collins        10.5   11.5   13.0 :  <5   <5   <5   <5   <5   <5
Greeley              8.0    9.5   10.5 :  <5   <5   <5   <5   <5   <5
:North Platte River
Northgate            8.0    9.5   11.0 :   5   <5   <5   <5   <5   <5

Legend
CS = Conditional Simulation (Current Outlook)
HS = Historical Simulation
FT = Feet

In Table 2 below...the 95 through 5 percent columns indicate the
probability of exceeding the listed stage levels (FT) for the valid
time period.

...Table 2--Exceedance Probabilities...

                              Chance of Exceeding Stages
                                 at Specific Locations
                           Valid Period: 2/18/2017 - 5/19/2017
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:South Platte River
South Platte          3.7    3.8    3.8    3.9    4.0    4.7    5.2
Denver                4.0    4.0    4.2    4.7    5.3    6.4    7.1
Henderson             5.2    5.5    5.7    6.6    7.2    9.0   10.2
Kersey                4.3    4.3    4.7    6.0    7.7    8.9   11.3
Weldona               2.9    3.0    3.1    4.2    6.1    7.3   10.8
Balzac                2.6    2.8    3.0    4.2    5.6    7.6   10.9
Julesburg             4.6    4.7    5.0    6.0    6.9    7.9    9.6
:Plum Creek
Sedalia               4.0    4.1    4.2    4.4    4.6    5.3    6.9
:Bear Creek
Morrison              6.0    6.1    6.3    6.5    6.8    7.2    7.7
Sheridan              2.6    2.7    2.8    3.1    3.6    4.5    4.8
:Clear Creek
Golden                4.2    4.3    4.5    4.7    5.0    5.4    5.7
Derby                 2.2    2.3    2.5    2.8    3.3    3.9    4.9
:N Fk Big Thompson River
Drake                 3.9    4.0    4.0    4.1    4.2    4.4    4.6
:Cache la Poudre River
Fort Collins 9NW      3.3    3.4    3.5    3.8    4.1    4.8    5.7
Fort Collins          1.4    1.5    1.7    2.2    3.1    4.7    6.2
Greeley               2.2    2.2    2.5    3.2    4.8    6.8    7.8
:North Platte River
Northgate             4.8    5.1    5.3    5.5    6.0    6.9    7.8

In Table 3 below...the 95 through 5 percent columns indicate the 
probability of falling below the listed stage levels (FT) for
the valid time period.

...Table 3--Nonexceedance Probabilities...

                            Chance of Falling Below Stages
                                 at Specific Locations
                           Valid Period: 2/18/2017 - 5/19/2017
LOCATION              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:South Platte River
South Platte          2.8    2.8    2.8    2.8    2.8    2.8    2.8
Denver                3.0    3.0    3.0    3.0    3.0    3.0    3.0
Henderson             3.9    3.8    3.3    3.1    3.0    3.0    3.0
Kersey                3.6    3.3    3.0    2.9    2.8    2.7    2.7
Weldona               1.9    1.4    0.2    0.1    0.1    0.1    0.1
Balzac                1.8    1.8    1.8    1.8    1.8    1.8    1.8
Julesburg             1.8    1.8    1.8    1.8    1.8    1.8    1.8
:Plum Creek
Sedalia               3.7    3.7    3.7    3.7    3.6    3.6    3.6
:Bear Creek
Morrison              5.6    5.5    5.5    5.5    5.5    5.5    5.5
Sheridan              2.2    2.2    2.1    2.1    2.1    2.1    2.1
:Clear Creek
Golden                3.5    3.5    3.5    3.5    3.5    3.5    3.4
Derby                 0.9    0.9    0.9    0.9    0.9    0.9    0.9
:N Fk Big Thompson River
Drake                 3.8    3.8    3.7    3.7    3.7    3.7    3.7
:Cache la Poudre River
Fort Collins 9NW      2.8    2.8    2.8    2.8    2.8    2.8    2.8
Fort Collins          1.1    1.0    0.5    0.4    0.4    0.4    0.4
Greeley               1.4    1.3    1.3    1.3    1.3    1.3    1.3
:North Platte River
Northgate             2.4    2.4    2.4    2.4    2.4    2.3    2.3

These long-range probabilistic outlooks contain forecast values that
are calculated using multiple season scenarios from 30 or more years
of climatological data...including current conditions of the
river...soil moisture...snow cover and 30 to 90 day long-range
outlooks of temperature and precipitation. By providing a range
of probabilities...the level of risk associated with long-range 
planning decisions can be determined. These probabilistic
forecasts are part of the National Weather Service's Advanced
Hydrologic Prediction Service.

Spring flood outlooks are routinely issued in February and March to 
give advanced notice of possible flooding. The next scheduled spring 
flood outlook will be issued Thursday March 2nd.

Visit our web site weather.gov/bou for more weather and water 
information.

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