Flash Flood and Flooding in Montana, March 12 to 20, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
926 AM MST SAT MAR 12 2011

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
THE STANDING FORECAST IS IN GOOD SHAPE AND ONLY MINOR CHANGES WERE
MADE. TEMPERATURES WERE WARMING A BIT QUICKER THAN ANTICIPATED
THIS MORNING SO MAX TEMPERATURES WERE ADJUSTED UO A FEW DEGREES
MAINLY IN THE SOUTHERN ZONES. WITH THE STRONG STORM SYSTEM SLOWING
ITS PROGRESSION EASTWARD IN NORTH DAKOTA THE NORTHEAST ZONES ARE
STILL BEING INFLUENCED WITH LOW CLOUDS AND FLURRIES. FLURRIES WERE
MENTIONED THROUGH EARLY AFTERNOON...OTHERWISE THE GOING FORECAST
IS SOUND. AES

PREVIOUS DISCUSSION....
COLDER AIRMASS THAT ARRIVED YESTERDAY IS ASSOCIATED WITH
AN ARCTIC HIGH PRESSURE THAT IS CENTERED QUITE FAR TO OUR NNE.
THIS THOUGH WILL KEEP TEMPS ON THE COLD SIDE TODAY. MODELS
INDICATE SLIGHT WARMING OF THE LOWER LEVELS OVER YESTERDAY.
HOWEVER SNOW COVER AND LIGHT E WINDS WILL LIMIT THIS AS FAR AS
HIGHS TODAY GO.

MODELS HAVE A POOR HANDLE ON THE LOW OVERCAST IN OUR E THIRD OF
CWA...WHICH IS PROVING MUCH MORE PERSISTENT THAN EXPECTED LAST
EVENING. LATEST RUC SHOWING THIS TO LAST TIL NOON...WHICH LOOKS
REASONABLE LOOKING AT SATELLITE FOG LOOP.

LARGE-SCALE PATTERN HAS UPPER RIDGING OVER OUR AREA WHICH WILL
KEEP THE WEATHER MOSTLY DRY THRU MON. ONE WEAK SHORTWAVE WITH
JUST BROKEN HIGH CLOUDS MOVING THRU THE RIDGE TODAY...ANOTHER
SIMILAR WEAK SHORTWAVE SUNDAY. MODELS INDICATE MORE SIGNIFICANT
WARMING OF THE AIRMASS SUNDAY....AS WELL AS E WINDS WEAKENING AND
PRESSURE GRADIENTS BECOMING MORE FAVORABLE FOR LIGHT S WINDS IN
AREAS. SOME MODELS SHOWING POTENTIAL FOR A FEW FOG PATCHES IN OUR
AREA EARLY SUN MORN...BUT HIGH CLOUDS...SOME WIND...AND OVERALL
WARMING AND DRY AIRMASS MAKE THIS DOUBTFUL...SO LEFT OUT OF GRIDS.

A BIT STRONGER SHORTWAVE SYSTEM MOVES ACROSS THE AREA MON. MODELS
APPEAR A LITTLE QUICK WITH THE COLD FRONT...BUT NAM IS TOO SLOW.
THE MAIN FRONT LOOKS FAIRLY WEAK AND DRY WITH MOISTURE NOT WELL
ORGANIZED...SO KEPT POPS AROUND 10 PCT. LATER GFS AND ECMWF RUNS SHOW
A SURFACE WAVE FORMING ON THE COLD FRONT ALONG SC MT/N WY BORDER.
THIS TAKES SOME ENERGY FROM THE MAIN FRONT...BUT THIS WILL STAY TO
OUR S.

THE FRONT WILL PROVIDE ENOUGH MIXING TO BRING TEMPS INTO THE 40S TO
LOWER 50S RANGE FOR OUR AREA MON. MOST MODELS...EXCEPT NAM...HAVE
40-50 KT 850 WINDS MON. FORECAST SOUNDINGS DON'T LOOK FAVORABLE TO
MIX THESE WINDS TO SURFACE...AS FRONT IS NOT STRONG...BUT ENOUGH
FOR ABOUT 10 TO 20 MPH WINDS. SIMONSEN

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
FAIRLY GOOD AGREEMENT WITH THE MEDIUM RANGE MODELS THROUGH NEXT
WEEK. MEAN FLOW PATTERN REMAINS ZONAL WITH PERIODIC SHORTWAVE
SLIDING EASTWARD.

FIRST OF THESE SHORTWAVES MOVES ACROSS MONTANA MONDAY NIGHT...
FOLLOWING A COLD FRONT PASSAGE. NEXT SHORTWAVE WILL BE ON
WEDNESDAY WITH WARM FRONT FOLLOWED BY COLD FRONT WEDNESDAY NIGHT.
BY THE END OF THE WEEK...UPPER TROF DIGGING OFF THE WEST COAST
TURNS UPPER FLOW SOUTHWEST INTO MONTANA.

MILD TEMPERATURES GENERALLY EXPECTED THROUGH THE PERIOD WITH
READING ABOVE FREEZING DURING THE DAY DROPPING BELOW 32 AT NIGHT.
A SLIGHT COLD INTRUSION OCCURS FOLLOWING EACH OF THE FRONTAL
PASSAGES DROPPING TEMPERATURES SLIGHTLY...MAINLY ACROSS THE
NORTHEAST. ANY PRECIPITATION DURING THE PERIOD...WHICH IS MOST
LIKELY ON WEDNESDAY...SHOULD BE RAIN DURING THE DAY...AND
POSSIBLY MIXING WITH SNOW DURING THE NIGHT. EBERT

&&

.AVIATION...
MVFR CEILINGS WILL BE PRESENT THIS MORNING AS A WEAK DISTURBANCE
PUSHES THROUGH. MVFR VISIBILITY WILL ALSO BE PRESENT THIS MORNING
IN LIGHT SNOW FALLING OUT OF THE LOW STRATUS. VFR CONDITIONS
WILL BUILD IN FROM WEST TO EAST TODAY AS THE DISTURBANCE EXITS THE
REGION. LIGHT AND VARIABLE WINDS WILL BECOME EASTERLY AT 10 TO 20
MPH BY THIS EVENING. GILCHRIST

&&

.HYDROLOGY...
THE MUSSELSHELL RIVER IN PETROLEUM COUNTY AT THE MOSBY GAUGE HAS
JUMPED UP TO OVER 9 FEET EARLY THIS MORNING. THE RIVER SHOULD
LEVEL OUT AND PEAK NEAR FLOOD STAGE LATER TODAY. A LOCAL WEATHER
OBSERVER REPORTS A LARGE AND LONG LIVED ICE JAM NORTH OF THE
HIGHWAY 200 BRIDGE NEAR MOSBY WHICH IS PROBABLY ADDING TO THE
RIVER LEVEL. COOLER WEATHER OVER THE PAST 24 HOURS WILL ALLOW FOR
A SLOW DOWN IN MELT WATER FOR THE MUSSELSHELL RIVER BASIN.
BEGINNING ON SUNDAY ANOTHER WARM UP IS EXPECTED ACROSS THE REGION
WHICH SHOULD PUT THE RIVER ON THE RISE AGAIN.

SMALL STREAM FLOOD ADVISORY ISSUED FOR GARFIELD AND PETROLEUM
COUNTIES BASED ON REPORTS OF SAGE HEN AND SOUTH LODGE POLE CREEKS
ALREADY OUT OF THEIR BANKS. LOCAL DRAINAGES ARE SEEING PROBLEMS
WITH FROZEN CULVERTS AND BLOCKED FLOW FROM THE HIGH AMOUNTS OF
SNOW AND ICE THIS WINTER. THE COOL WEATHER THROUGH TODAY SHOULD
SLOW THE MELT. HOWEVER SUNDAY THROUGH NEXT WEEK EXPECT WARMER
TEMPERATURES TO CONTINUE THE MELT FOR THE REGION MAKING FOR MORE
LOCAL FLOOD ISSUES WITH DRAINAGES UNTIL THEY BECOME FREE FLOWING.
DO EXPECT MORE ISSUES FOR THIS REGION WITH STILL 12-18 INCHES OF
SNOW IN SOME AREAS ACROSS NORTHWESTERN GARFIELD COUNTY.

MILK/MISSOURI DRAINAGE SYSTEM WILL ALSO SEE AN INCREASE IN
TEMPERATURES STARTING SUNDAY AND LAST WELL INTO NEXT WEEK WHICH
SHOULD BRING MELT DOWN INTO THE RIVER SYSTEM. STILL A FAIR AMOUNT
OF FROZEN WATER LOCKED UP IN THE HILLS AND IN THE FLATS. REPORT
FROM SOUTHWEST VALLEY COUNTY HAS SOME OF THE CREEKS ALREADY UP
NEARING BANK FULL WITH STILL A GOOD AMOUNT OF SNOW IN THE HILLS.
THE WARM SHOULD BRING SOME RIVER GAGE LEVELS UP AND MAY NEED SOME
HYDRO STATEMENTS ON RIVER RISES. THE GOOD NEWS IS THAT THE
FORECAST IS FOR MELTING DURING THE DAY AND GOOD CHANCES OF FREEZE
UP AT NIGHT NORTH OF THE MISSOURI RIVER WHICH COULD HELP KEEP MELT
WATER FROM QUICKLY CAUSING SIGNIFICANT HYDRO ISSUES THIS WEEK.
STILL WILL HAVE TO KEEP A WATCHFUL EYE ON THE RIVER SYSTEMS
THROUGH THIS WARM SPELL.

AS OF LAST WEEK MCCONE...DAWSON AND RICHLAND COUNTIES STILL HAVE
PLENTY OF SNOW PACK AND TEMPERATURE HERE WILL JUMP INTO THE 40S
AND POSSIBLY UP TO 50 IN THE EXTENDED FORECAST PERIOD. THIS COULD
BRING LOCAL SMALL STREAM FLOOD ISSUES. RESIDENTS SHOULD BEING TO
PLAN FOR THIS WARM UP AND POSSIBLE SMALL STREAM FLOODING ISSUES.
PROTON/EBERT

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

WEATHER.GOV/GLASGOW

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GLASGOW MT
345 AM MST SAT MAR 12 2011

MTZ021-022-131200-
PETROLEUM-GARFIELD-
345 AM MST SAT MAR 12 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...TODAY AND TONIGHT

A SMALL STREAM FLOOD ADVISORY HAS BEEN ISSUED FOR EASTERN
PETROLEUM AND WESTERN GARFIELD COUNTIES. THIS INCLUDES THE
MUSSELSHELL RIVER...AS WELL AS SMALL CREEKS AND STREAMS IN THE
AREA.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

WARMER WEATHER IS IN STORE STARTING ON SUNDAY. SNOWMELT WILL
CONTINUE AND CAUSE OTHER AREA STREAMS AND CREEKS TO START RUNNING
AND RISING. ICE JAMS COULD ALSO OCCUR ON AREA RIVERS AND SOME OF
THE LARGER TRIBUTARIES. PLEASE REPORT ANY FLOODING AND/OR ICE JAMS
TO LOCAL LAW ENFORCEMENT TO RELAY TO THE NATIONAL WEATHER SERVICE.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MTZ016>020-023>027-059>062-131200-
CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-
DANIELS-SHERIDAN-WESTERN ROOSEVELT-MCCONE-RICHLAND-DAWSON-PRAIRIE-
WIBAUX-NORTHERN PHILLIPS-SOUTHWEST PHILLIPS-NORTHERN VALLEY-
EASTERN ROOSEVELT-
345 AM MST SAT MAR 12 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

WARMER WEATHER IS IN STORE STARTING ON SUNDAY. SNOWMELT WILL
START OCCURRING AND CAUSE AREA STREAMS AND CREEKS TO START RUNNING
AND RISING. ICE JAMS COULD ALSO OCCUR ON AREA RIVERS AND SOME OF
THE LARGER TRIBUTARIES. PLEASE REPORT ANY FLOODING AND/OR ICE JAMS
TO LOCAL LAW ENFORCEMENT TO RELAY TO THE NATIONAL WEATHER SERVICE.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.