Flash Flood and Hail in Montana, August 14, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
301 PM MDT FRI AUG 14 2009

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
THE SHORT TERM WILL REMAIN UNSETTLED WITH WET CONDITIONS AND
COOLER TEMPERATURES THAN NORMAL. THE CYCLONIC STORM SYSTEM WILL
BE CENTERED OVER NW MT EARLY THIS EVENING WITH THE EXITING JET
AIMED AT THE CENTRAL AND EASTERN REGIONS. BOTH THE NAM AND GFS
AGREE WITH THE PLACEMENT OF A SHARP COLD FRONT ACROSS OUR WESTERN
ZONES AT 00Z. THE FRONT WILL WORK ITS WAY ACROSS THE ZONES DURING
THE EVENING...ENDING UP NEAR OUR EASTERN BORDER BY 06Z. MODERATE
INSTABILITY...DEPENDING ON HOW MUCH SUNSHINE AFFECTS THE
SURFACE...COULD GENERATE STRONG THUNDERSTORMS NEAR THE FRONT. IN
ANY CASE...MOISTURE WILL BE PLENTIFUL WITH HEAVY RAIN A
POSSIBILITY. MODELS ARE SHOWING AN INCH OR MORE OF RAIN. THE NAM
SLOWS THE FRONT AROUND MIDNIGHT WHICH LINGERS THE SHOWERS OVER OUR
NORTHEASTERN ZONES LATE.

TONIGHT...THE MOST ENERGETIC PERIOD WILL BE IN THE EVENING AND
POSSIBLY A FEW HOURS AFTER MIDNIGHT AS THE FRONT MOVES THROUGH THE
CWA. STRONG FORCING NEAR THE FRONT COULD CREATE A SQUALL LINE.
MODERATE INSTABILITY AND IN INVERTED V PROFILE SUGGESTS THAT THE
MAIN THREAT WILL BE HEAVY RAINS AND STRONG WINDS. THE WIND
PROFILES WILL BE VARIABLE WITH EASTERLY LOW LEVEL SHIFTING TO THE
NW BEHIND THE FRONT PRODUCING MODERATE SHEAR. LARGE HAIL REMAINS A
POSSIBILITY. WILL MAINTAIN SEVERE WORDING IN EVENING FORECAST.

SATURDAY/SATURDAY NIGHT...THE DAY STARTS WITH THE LOW CENTER OVER
THE CENTRAL REGION WHICH SENDS THE FAVORED STORM AREA INTO
SASKATCHEWAN. THE LOCAL ZONES APPEAR TO BE DRY SLOTTED AS THE LOW
CENTER MOVES INTO NE MT SATURDAY NIGHT. WILL BACK OFF A BIT ON
POPS. TEMPERATURES WILL REMAIN RATHER COOL BEHIND THE FRONT...BUT
COULD WARM SLIGHTLY DEPENDING ON SKY COVER. HIGHS WILL NOT RECOVER
MUCH FROM TODAY.

SUNDAY...WRAP-AROUND PRECIPITATION SWINGS INTO THE FORECAST AREA
AS THE LOW CENTER MOVES INTO NORTH DAKOTA. UPPER AND LOWER WINDS
LINE UP FROM THE NORTHWEST WHICH WILL COOL TEMPERATURES EVEN MORE.
HIGHS MIGHT STRUGGLE TO CLIMB OUT OF THE 60S. WIND SPEED WILL PICK
TO AROUND 15KT IN THE AFTERNOON AND COULD BE STRONGER BASED ON THE
AMOUNT OF MIXING OF STRONGER 700/850MB WINDS. A LWA IS A
POSSIBILITY. SCT

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
THROUGH MONDAY THERE IS DECENT MODEL CONSISTENCY...AND THUS HIGHER
CONFIDENCE. A NORTHWEST FLOW WILL RULE...MAKING FOR COOL TEMPS AND
SHOWERY CONDITIONS. MADE ONLY MINOR TWEAKS MAINLY TO TREND UP POPS
SLIGHTLY FOR THIS PERIOD.

TUESDAY AND BEYOND CONSISTENCY GOES OUT THE DOOR AND SUBSEQUENTLY
LOWER CONFIDENCE EXISTS IN THE FORECAST. THE DIFFERENCES MAINLY
RESIDE IN HOW TO RESOLVE SHORTWAVE ENERGY DROPPING SOUTHEASTWARD
OUT OF CANADA IN THE NORTHWEST FLOW ALOFT. GIVEN LOWERED
CONFIDENCE HELD OFF ON MAKING TOO MANLY CHANGES...BUT DID BACK OFF
A BIT ON THE WARM UP FOR NEXT WEEKEND AS OVERALL THE MODELS ARE
NOT AS AGGRESSIVE IN BUILDING IN A RIDGE. GILCHRIST

PREVIOUS DISCUSSION...SUNDAY NIGHT THROUGH TUESDAY... ANTICIPATE
A NORTHWEST FLOW PATTERN WITH RAISED CHANCES FOR SHOWERS AND
THUNDERSTORMS AS A SERIES OF DISTURBANCES AND MINOR COLD FRONTS
PRESS THROUGH THE REGION. 850 MB TEMPERATURES SHOULD BE SLOWLY
REBOUNDING THROUGH FROM THE SINGLE DIGITS AND LOWER 10S INTO THE
MID 10S ALLOWING SURFACE TMAXES TO RISE FROM THE 70S INTO THE
LOWER 80S.

TUESDAY NIGHT THROUGH FRIDAY NIGHT... GFS AND EC RUNS APPEAR TO BE
A BIT DIFFERENT IN STRUCTURE IN THIS PERIOD. HOWEVER... THE SAME
SYNOPTIC OUTCOME IS STILL EXPECTED FOR NEMONT. RIDGING WILL PRESS
INTO NORTHEASTERN MONTANA AS STRONG HIGH PRESSURE INTENSIFIES
ACROSS THE FOUR CORNERS REGION. A SLOW WARNING TREND FROM THE
LOWER 80S TO UPPER 80S AND LOWER 90S IS ANTICIPATED WITH THIS
INCREASE IN PRESSURE AS WELL AS RELATIVELY DRY AND PARTLY CLOUDY
SKIES. GAH

&&

.AVIATION...
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE
ACROSS NORTHEAST MONTANA THROUGH THE EVENING HOURS...POSSIBLY
BRINGING BRIEF MVFR CONDITIONS TO THE TERMINALS AS THEY PASS.
LATER ON THIS EVENING A STRONG COLD FRONT WILL PUSH THROUGH. THERE
IS GOOD POTENTIAL FOR WIDESPREAD STRONG TO SEVERE THUNDERSTORMS
ALONG THIS LINE AS IT CROSSES...POSSIBLY LOWERING FLYING
CONDITIONS TO IFR FOR SHORT PERIODS OF TIME. GUSTY WESTERLY WINDS
WILL ACCOMPANY THE FRONT...LASTING INTO SATURDAY MORNING.
GILCHRIST

&&

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

&&

WEATHER.GOV/GLASGOW

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GLASGOW MT
353 AM MDT FRI AUG 14 2009

MTZ016>027-059>062-151000-
CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-
DANIELS-SHERIDAN-WESTERN ROOSEVELT-PETROLEUM-GARFIELD-MCCONE-
RICHLAND-DAWSON-PRAIRIE-WIBAUX-NORTHERN PHILLIPS-
SOUTHWEST PHILLIPS-NORTHERN VALLEY-EASTERN ROOSEVELT-
353 AM MDT FRI AUG 14 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...TODAY AND TONIGHT

A COLD FRONT WILL MOVE THROUGH THE AREA LATE THIS AFTERNOON AND
EVENING. THIS WILL RESULT IN SCATTERED THUNDERSTORMS...SOME OF
WHICH MAY BECOME SEVERE AND PRODUCE LARGE HAIL AND/OR DAMAGING
WIND.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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