Tornado Warning 6, NWS Great Falls, MT

000 
WWUS55 KTFX 050118
SVSTFX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
718 PM MDT FRI JUL 4 2008

MTC073-099-050128-
/O.CAN.KTFX.TO.W.0006.000000T0000Z-080705T0130Z/
PONDERA MT-TETON MT-
718 PM MDT FRI JUL 4 2008

...THE TORNADO WARNING FOR NORTH CENTRAL TETON AND CENTRAL PONDERA
COUNTIES IS CANCELLED...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT.

NATIONAL WEATHER SERVICE RADAR INDICATED THAT THE ROTATION WITH THE
THUNDERSTORM THAT PROMPTED THE TORNADO WARNING HAD WEAKENED AND WAS 
NO LONGER INDICATING A TORNADO. THUS THE WARNING HAS BEEN CANCELLED.

LAT...LON 4831 11193 4810 11180 4793 11245 4810 11256
TIME...MOT...LOC 0118Z 246DEG 32KT 4813 11212

$$

REILLY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
530 PM MDT FRI JUL 4 2008

UPDATED FOR AVIATION

.DISCUSSION...

...SEVERE THUNDERSTORM WATCH ISSUED FOR SOUTHWEST AND CENTRAL
MONTANA IN EFFECT UNTIL 10 PM MDT...

...SEVERE WEATHER LIKELY THIS AFTERNOON AND EVENING OVER THE
ENTIRE AREA...

STRONG INSTABILITY IS FORECAST TO DEVELOP THIS AFTERNOON OVER THE
ENTIRE FORECAST AREA...AS A VIGOROUS UPPER LEVEL SHORTWAVE TROUGH
AND ASSOCIATED JET STREAK AFFECT THE REGION. LATEST 12Z OPERATIONAL
FORECAST MODELS SHOW A 55KT TO 60KT JET STREAK ARRIVING OVER
NORTHWEST MONTANA THIS EVENING...WITH SURFACE BASED CAPES EXCEEDING
2500 J/KG. AN UPPER LEVEL VORT MAX OVER WESTERN WASHINGTON IS
EXTRAPOLATED TO BE JUXTAPOSED WITH THIS JET STREAK BY 6PM. MODELS
HAVE INDICATED A STRENGTHENING TREND WITH THIS JET STREAK...WITH
EARLIER RUNS 10 KTS OR SO LESS. ALSO...LATEST RUNS SHOW A FURTHER
NORTHWARD JET PLACEMENT...SUGGESTING THAT THE FORECAST AREA WILL
HAVE A GREAT CHANCE OF EXPERIENCING FAVORABLE ASCENT IN THE RIGHT
ENTRANCE REGION OF THE JET THIS EVENING.

SEVERAL COMPLICATING FACTORS HAVE BEEN NOTED IN THE LOW LEVELS. FOR
EXAMPLE...LOW LEVEL MOISTURE POOLING NORTH OF A DEVELOPING SURFACE
CYCLONE OVER CENTRAL MONTANA HAS BEEN A BIT STRONGER THAN
ANTICIPATED. CLOUD COVERAGE THIS MORNING OVER THE NORTHERN HALF OF
THE FORECAST AREA MAY LIMIT DEEPER MIXING...THUS MAINTAINING HIGHER
LOW LEVEL MOISTURE AND INSTABILITY THROUGH THE DAY. DEWPOINTS IN THE
LOWER 60S HAVE ALREADY BEEN NOTED ON EITHER SIDE OF THE
DIVIDE...RESULTING IN RUC-ANALYSIS SURFACE-BASED CAPES FROM
1500-2000 J/KG ALREADY AT 11 AM MDT...WITH MIXED LAYER CAPES ABOUT
500 J/KG LOWER. HOWEVER...THERE STILL REMAINS A CAP IN THE LOWER
ATMOSPHERE THIS MORNING...WITH CONVECTIVE INHIBITION OVER 100 J/KG
ACROSS THE FORECAST AREA. WITH TIME...SUFFICIENT COLD AIR ADVECTION
ALOFT IN ASSOCIATION WITH HEIGHT FALLS WITH THE APPROACHING UPSTREAM
TROUGH WILL HELP TO ERODE THE CAP...WITH CONVECTIVE INITIATION
EXPECTED OVER THE HIGHER TERRAIN BY 2 PM MDT OR SO.
INTERESTINGLY...A LEAD SHORTWAVE TROUGH WAS SUFFICIENT FOR
HIGHER-BASED STORMS OVER NORTHWEST MONTANA THAT TRACKED INTO
ALBERTA. AN OUTFLOW BOUNDARY IS SURGING SOUTHWARD...SHIFTING WINDS
TO NORTHEASTERLY IMMEDIATELY BEHIND IT. THIS BOUNDARY IS FORECAST TO
BECOME DIFFUSE THIS AFTERNOON...AS IT TRACKS AWAY FROM ITS PARENT
CONVECTION. HOWEVER...REMAINING LOW LEVEL VORTICITY WITH THIS
BOUNDARY MAY BECOME A KEY PLAYER IN CONVECTIVE ENHANCEMENTS THIS
AFTERNOON.

AS IT CURRENTLY STANDS...MODELS ARE ALL OVER THE PLACE WITH REGARD
TO CONVECTIVE COVERAGE. THE RUC AND NAM SHOW A FASTER NORTH-SOUTH
BOUNDARY PASSAGE...BRINGING WESTERLY WINDS ACROSS MUCH OF THE REGION
BY MID-AFTERNOON...AND WITH THE GFS SHOWING A MUCH SLOWER PASSAGE.
WITH THE UPSTREAM ASCENT BEING RATHER WEAK AT FIRST...WE ONLY EXPECT
ISOLATED STORMS TO DEVELOP THIS AFTERNOON...WITH MORE WIDESPREAD
COVERAGE AFTER 600 PM...ESPECIALLY OVER NORTH CENTRAL MONTANA.
COVERAGE COULD BE MORE SPOTTY OVER SOUTHWEST MONTANA...THOUGH LATEST
RUC SHOWS WIDESPREAD COVERAGE THERE AS WELL. OVERALL CONVECTIVE
MORPHOLOGY IS ALSO VERY TRICKY...AS SOLUTIONS FAVORING THE WESTERLY
LOW-LEVEL FLOW WOULD SUPPORT MORE UNIDIRECTIONAL WIND PROFILES AND A
SQUALL LINE THREAT WITH THE DEEP-LAYER SHEAR VECTOR ORIENTED
PARALLEL TO THE LOW LEVEL BOUNDARY. STRENGTHENING SOUTHWESTERLY 700
MB FLOW OVER 30KTS MAY ENHANCE DESCENDING REAR INFLOW JETS WITH ANY
SQUALL LINES AS WELL AS THE DAMAGING WIND POTENTIAL. ON THE OTHER
HAND...FAR EASTERN PORTIONS OF CENTRAL MONTANA WILL LIKELY
EXPERIENCE LOW LEVEL FLOW BACKED TO THE SOUTHEAST FOR A LONGER
PERIOD OF TIME...AND THUS A GREATER CHANCE FOR ROTATING UPDRAFTS.
HOWEVER...AS TOTAL SHEAR MAGNITUDE WITHIN THE INSTABILITY LAYER
INCREASES TO OVER 50 KTS THIS EVENING...EMBEDDED MESOCYCLONES AND
VORTICES WITHIN SQUALL LINES WILL BECOME POSSIBLE...ESPECIALLY AS
STRONGER PACIFIC MOISTURE AND ASSOCIATED INSTABILITY POOL INTO THE
REGION WEST OF THE DIVIDE. ONLY WEAK LOW LEVEL WESTERLY FLOW WILL
INHIBIT ANY SUBSTANTIAL DOWNSLOPE DRYING. ESSENTIALLY...ALL MODES OF
CONVECTION WILL BE POSSIBLE THROUGH EVENING...WITH LARGE
HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES ALL POSSIBLE. A
SPECIAL 18Z SOUNDING HAS BEEN RELEASED TO COLLECT ADDITIONAL
ENVIRONMENTAL DATA. ACOHEN

SATURDAY...TEMPERATURES WILL BE COOLER BUT STILL SLIGHTLY ABOVE
SEASONAL NORMALS. SOME INSTABILITY OVER THE MOUNTAINS OF SOUTHWEST
MONTANA MAY RESULT IN ISOLATED AFTERNOON THUNDERSTORMS. BRITTON

SATURDAY NIGHT THROUGH SUNDAY...CONTINUE TO SEE SERIES OF WEATHER
SYSTEMS WORK THROUGH REGION KEEPING RIDGE FLAT. ENOUGH INSTABILITY
TO CREATE SOME SHOWERS AND THUNDERSTORMS...MAINLY SOUTHWEST WITH
TEMPERATURES SEASONABLY WARM. LOSS

&&

.AVIATION...
UPDATED 2330Z.
A MOIST AND UNSTABLE SOUTHWEST FLOW ALOFT...COMBINED WITH A PACIFIC
COLD FRONT THIS EVENING...WILL BRING NUMEROUS SHOWERS AND
THUNDERSTORMS...WITH SOME THUNDERSTORMS BEING SEVERE WITH DAMAGING
WINDS AND LARGE HAIL UNTIL 04Z. THUNDERSTORMS WILL DECREASE LATER
THIS EVENING. VFR CONDITIONS WILL PREVAIL EXCEPT FOR LOCAL IFR/MVFR
IN AND AROUND THUNDERSTORMS. WILLIAMSON DC

&&

.FIRE WEATHER...
UPDATED 314 PM MDT.
SCATTERED THUNDERSTORMS WILL CONTINUE TO DEVELOP ACROSS
SOUTHWEST...CENTRAL...AND NORTH CENTRAL MONTANA THIS AFTERNOON AND
CONTINUE INTO THIS EVENING. TEMPERATURES THIS AFTERNOON ARE
GENERALLY IN THE UPPER 80S TO MID 90S WITH DEWPOINTS IN THE UPPER
30S TO MID 50S. LOWER LEVELS OF THE ATMOSPHERE REMAIN RATHER DRY.
THE MAIN THREAT FROM THESE STORMS WILL BE STRONG GUSTY WINDS AND
OCCASIONAL DRY LIGHTNING. ALSO...BOTH THE OBSERVED FIRE DANGER CLASS
FOR YESTERDAY AND THE FORECAST FIRE DANGER FOR TODAY ARE IN THE
MODERATE RANGE. WILL THEREFORE ADDRESS THE POTENTIAL FOR DRY
THUNDERSTORMS WITH A HEADLINE IN THE FIRE WEATHER PLANNING FORECAST.
OVERNIGHT EXPECT COOL TEMPERATURES AND GOOD RELATIVE HUMIDITY
RECOVERIES. SATURDAY AND SUNDAY TEMPERATURES WILL BE SOMEWHAT COOLER
WITH SLIGHTLY LOWER RELATIVE DAYTIME HUMIDITIES...BUT GOOD OVERNIGHT
RECOVERIES. BRITTON

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  55  81  54  82 /  50  20  20  20
CTB  50  78  51  79 /  40  10  10  10
HLN  58  83  56  85 /  50  20  20  20
BZN  52  79  52  84 /  40  30  30  20
WEY  46  72  45  77 /  30  30  30  30
DLN  49  78  49  79 /  50  30  20  20
HVR  55  85  55  84 /  40  10  10  10
LWT  51  76  52  82 /  40  20  20  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

SEVERE THUNDERSTORM WATCH NUMBER 656 IN EFFECT 2 PM MDT UNTIL 10 PM
MDT.

SEVERE THUNDERSTORM WATCH NUMBER 657 IN EFFECT 3 PM MDT UNTIL 10 PM
MDT.

&&

SHORT TERM...COHEN
LONG TERM...LOSS
AVIATION...WILLIAMSON DC

WEATHER.GOV/GREATFALLS

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GREAT FALLS MT
320 PM MDT FRI JUL 4 2008

MTZ008>015-044>055-051230-
BEAVERHEAD-NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-HILL-
CASCADE-CHOUTEAU-CENTRAL AND SOUTHERN LEWIS AND CLARK-MADISON-
TOOLE-LIBERTY-EASTERN PONDERA-BLAINE-
SOUTHERN ROCKY MOUNTAIN FRONT-EASTERN TETON-JUDITH BASIN-FERGUS-
JEFFERSON-BROADWATER-MEAGHER-GALLATIN-
320 PM MDT FRI JUL 4 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR THE ENTIRE AREA UNTIL
1000 PM MDT THIS EVENING. SCATTERED SEVERE THUNDERSTORMS ARE
LIKELY THIS AFTERNOON AND TONIGHT OVER THE WATCH AREA. DAMAGING
WINDS...LARGE HAIL...AND HEAVY RAIN WILL BE POSSIBLE. AN ISOLATED
TORNADO MAY ALSO BE POSSIBLE OVER CENTRAL AND NORTH CENTRAL MONTANA.

LIGHTNING IS ALWAYS A CONCERN WITH ANY THUNDERSTORM. THOSE
PLANNING OUTDOOR HOLIDAY ACTIVITIES TODAY AND TONIGHT ARE
ENCOURAGED TO FREQUENTLY CHECK THE LATEST FORECASTS...
WATCHES...AND WARNINGS FROM THE NATIONAL WEATHER SERVICE. THOSE
OUTDOORS SHOULD MONITOR THE SKY FOR DEVELOPING STORMS AND HEAD FOR
SHELTER AT THE FIRST INDICATION OF A THUNDERSTORM.

ALSO...WITH THE RECENT RAINFALL AND WARM TEMPERATURES...ELEVATED
WATER LEVELS MAY OCCUR ON AREA RIVERS...CREEKS...AND STREAMS. USE
EXTRA CAUTION WHEN VENTURING OUT ON THE WATER THROUGH THIS WEEKEND.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS FOR SATURDAY THROUGH
THURSDAY WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION HAS BEEN REQUESTED. WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO
STANDARD OPERATING PROCEDURES.

ACOHEN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
620 PM MDT FRI JUL 04 2008

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

0418 PM     HAIL             4 W LENNEP              46.42N 110.63W
07/04/2008  E1.00 INCH       MEAGHER            MT   TRAINED SPOTTER

            HAIL ENDED AT 404 PM MDT

0617 PM     HAIL             4 S CHOTEAU             47.75N 112.18W
07/04/2008  E1.75 INCH       TETON              MT   TRAINED SPOTTER

&&

BRITTON