Areal Flood Advisory 21, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
1055 AM MDT Fri Aug 15 2014

.UPDATE...Issued a flash flood watch for Flathead County,
primarily for the Going-To-The-Sun-Road in Glacier National Park.

&&

.DISCUSSION...A line of showers with embedded thunderstorms is
moving through west central Montana this morning and will move
into northwest Montana through this afternoon. The primary threat
with thunderstorms will be very heavy rain, though small hail is
also possible in the stronger storms. Because atmospheric moisture
amounts remain well above normal, have issued a flash flood watch
for Flathead County. The main threat area will be the Going-To-
The-Sun-Road in Glacier National Park, although other roads in
Flathead Co could experience some small slides and debris on the
roadways under the heavier storms. Other areas besides Flathead
County will also have the potential for heavy rain producing
thunderstorms, and thus the threat will continue to be evaluated
through the afternoon.

&&

.AVIATION...Morning low clouds and fog in the vicinity of KGPI,
KSMN and KMSO will gradually dissipate by mid morning. Additional
afternoon showers and thunderstorms will be developing across the
Northern Rockies, affecting all airfields starting between 18z and
21z and continuing through this evening. The potential for gusty
winds and hail is minimal however there is a high threat for very
heavy rainfall which may produce brief, but sudden reductions in
both visibility as well as cloud heights. Conditions will improve
overnight with the potential for fog/stratus again returning to
most all airfields by Saturday morning.

&&

.PREV DISCUSSION... /ISSUED 420 AM MDT Fri Aug 15 2014/

..Heavy rain threat continues for one more day...

DISCUSSION...The last area of overnight convection can
be seen moving through Glacier National Park as of 4am. These
storms along with others across the Northern Rockies last night
have produced some rather robust amounts of precipitation and in
turn also resulted in saturated conditions at the surface. The
combination of this moisture and overnight clearing have lead to
the development of fog with the possibility of dramatic visibility
reductions in those places which received the heaviest rainfall.
The fog and low clouds will gradually dissipate by mid morning.

The weather pattern is starting to sound like a broken record given
that the parent upper level low pressure system responsible for
initiating all of our convection has moved very little over the
past few days. However that will change today with all models
forecasting the low to gradually drift NE towards NE Washington &
the Idaho Panhandle late this afternoon and along the Canadian
border with NW Montana by early Saturday morning. This path will
once again open the door for widespread afternoon showers and
thunderstorms across much of Northern Rockies with the key threat
being very heavy rainfall due to the continued presence of well
above normal atmospheric moisture levels. There continues to be a
slight chance for a few strong storms that may contain small hail.
But these will be few and far between due to limited instability
from cooler afternoon temperatures. Overnight convection will be
limited to mainly NW Montana and far less impressive than the
past few days. This area will also be the focus for additional
organized showers and thunderstorms Saturday. Whereas points
farther to the south see only scattered convection and breezy
afternoon winds. The upper low should be well into central Canada
by Sunday leaving northwest flow behind across Montana and the
slight chance for some afternoon showers and thunderstorms. But
overall things will begin to dry and become seasonably warm.

Monday & Tuesday: High temperatures will be 7 to 10 degrees above
normal while the chance for precipitation will be slightly below
normal. Gusty winds are still anticipated for Tuesday.

Wednesday onwards: Confidence continues to grow for a pattern
change with an increasing chance for precipitation into next
weekend. Also temperatures will be near normal on Wednesday and
then fall to as much as 8 to 12 degrees below normal by the end of
the week.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

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PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE MISSOULA MT
832 AM MDT FRI AUG 15 2014

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 PM     HAIL             5 E GREER               46.39N 116.07W
08/14/2014  E1.25 INCH       CLEARWATER         ID   LAW ENFORCEMENT

            HAIL WAS MOSTLY 1" BUT A FEW WERE UP TO
            HALF-DOLLAR SIZE. IT ACCUMULATED UP TO 12"
            IN PLACES AND DECIMATED A BARLEY CROP. ALSO
            HOLES WERE OBSERVED IN FIBERGLASS BUILDING.
            HAIL DURATION 20 MINUTES.

&&

NWS MISSOULA MT
IRIS SYSTEM

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE MISSOULA MT
834 AM MDT FRI AUG 15 2014

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 PM     TSTM WND DMG     5 E GREER               46.39N 116.06W
08/14/2014                   CLEARWATER         ID   LAW ENFORCEMENT

            CLEARWATER COUNTY DEPUTY REPORTED A POSSIBLE
            "MICROBURST" AND WINDS IN EXCESS OF 60 MPH.
            A YELLOW PINE TREE SMASHED A SHED. ANOTHER
            YELLOW PINE WAS UPROOTED AND SEVERAL OTHERS
            WERE TWISTED OFF ABOUT 20 TO 30 FEET UP.
            TIME IS IN PDT. TSTM WND DMG DURATION 20
            MINUTES.

&&

NWS MISSOULA MT
IRIS SYSTEM

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
858 AM MDT FRI AUG 15 2014

MTZ003-004-151545-
FLATHEAD/MISSION VALLEYS-LOWER CLARK FORK REGION-
858 AM MDT FRI AUG 15 2014

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN SANDERS...WESTERN
MISSOULA AND EASTERN MINERAL COUNTIES UNTIL 945 AM MDT...

AT 854 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 7 MILES SOUTHEAST OF TARKIO...OR 20 MILES
SOUTHEAST OF SUPERIOR...MOVING NORTH AT 25 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER IS POSSIBLE WITH THIS STORM...
ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...TARKIO...ALBERTON...
CYR...QUARTZ...NINEMILE...HUSON AND STARK.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF THREATENING WEATHER APPROACHES YOUR AREA...GO INDOORS AND STAY
AWAY FROM WINDOWS. IF YOU ARE CAUGHT OUTSIDE...MOVE TO A WELL
PROTECTED AREA.

&&

LAT...LON 4734 11471 4729 11422 4684 11440 4683 11481
TIME...MOT...LOC 1456Z 197DEG 20KT 4698 11461

KINO