? Carroll College |
1240 KBLLBeartooth NBCWeather CenterHelena's most comprehensive weather information source
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.TODAY...SUNNY. HIGHS 80 TO 90...75 TO 80 IN THE MOUNTAINS. WEST
WINDS 5 TO 15 MPH. |
Chief Meteorologist Curtis Grevenitz
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Forecaster Erin Yost
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HELENA CLIMATE SUMMARY
CLIMATE NORMAL PERIOD 1971 TO 2000 KEY TO LISTINGS:
WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST |
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2007 End-of-Year Data PRECIPITATION (IN) DECEMBER 0.01 0.46 -0.45 0.38 DEGREE DAYS COOLING CALENDAR YEAR 2007: 746 277 469 628 |
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Hydrology Report Aviation Forecast from the National Weather Service |
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| TODAY THROUGH FRIDAY EVENING...CURRENT ANALYSIS SHOWS CWA IN TRANSITION ZONE / WESTERLY FLOW REGIME BETWEEN LARGE EASTERN PACIFIC RIDGE AND UPPER TROF OVER GULF OF ALASKA/BC. TRANSIENT SHORTWAVE RIDGE WILL MOVE OVER THE REGION TODAY WITH ACCOMPANYING DRY AND WARM CONDITIONS THAT WILL PUSH TEMPS INTO THE MID/UPPER 80S IN LOWER ELEVATIONS. UPPER TROF AND ASSOCIATED COLD FRONT BEGIN TO TRACK EASTWARD TONIGHT...REACHING BC/ALBERTA BORDER BY MIDDAY ON THURS. PRESSURE GRADIENT WILL TIGHTEN AHEAD OF THIS SYSTEM AND GOOD MIXING WILL ALLOW SURFACE WINDS TO GUST FROM 30 TO 40 MPH ALONG THE ROCKY MTN FRONT AND NORTH-CENTRAL ZONES THURS AFTN. GFS AND NAM MODELS IN VERY CLOSE AGREEMENT ON COLD FRONT SWEEPING THROUGH ON THURS EVE BUT MOISTURE IS QUITE LOW...NO PRECIP EXPECTED EXCEPT FOR MARGINAL CHANCE OF ISOLD THUNDERSTORMS FROM CUT BANK TO HAVRE. SOME CONCERN THAT 100 MPH JET STREAK ACCOMPANYING UPPER TROF/FRONTAL PASSAGE MAY ADD SOME DYNAMIC PUNCH TO THE HILINE THUNDERSTORMS BUT LACK OF MOISTURE MAY NEGATE ANY IMPACT. SIGNIFICANT COOLING IN STORE FOR FRIDAY AS UPPER FLOW TURNS NORTHWESTERLY AND CANADIAN AIRMASS SETTLES OVER THE AREA. MAX TEMPS WILL BE 10 TO 12 DEG COLDER ON FRI...ONLY REACHING MID/UPPER 70S. WARANAUSKAS FRIDAY NIGHT THROUGH MONDAY NIGHT...A DRY AND COOL NORTHWEST FLOW ALOFT OVER NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA WILL KEEP SKIES PARTLY CLOUDY FRIDAY NIGHT WITH LOW TEMPERATURES BELOW SEASONAL AVERAGES. AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL THEN REBUILD OVER THE AREA ON SATURDAY...AS TEMPERATURES WARM TO NEAR NORMAL. A FEW WEAK DISTURBANCES MOVING THROUGH THE RIDGE WILL BRING A SLIGHT CHANCE OF THUNDERSTORMS TO THE MOUNTAINS. A SHORTWAVE TROUGH WILL GRADUALLY APPROACH MONTANA FROM THE WEST SUNDAY THROUGH MONDAY NIGHT. THE RESULTING INCREASINGLY MOIST AND UNSTABLE SOUTHWEST FLOW ALOFT WILL BRING AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS TO MOST OF THE AREA MAINLY DURING THE AFTERNOON AND EVENING HOURS. SURFACE WINDS WILL INCREASE AND BECOME WESTERLY...AS TEMPERATURES WARM TO ABOVE NORMAL LEVELS AHEAD OF A COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM. COULSTON TUESDAY THROUGH WEDNESDAY...MODELS ARE IN PRETTY GOOD AGREEMENT DURING THIS PERIOD. A WEAK SHORTWAVE TROUGH...OFF THE WEST COAST TUESDAY...DRIFTS EAST DURING THIS PERIOD. LIMITED MOISTURE AND ENERGY WITH A FEW DISTURBANCES IN A SOUTHWESTERLY FLOW ALOFT WILL RESULT IN PARTLY TO MOSTLY CLOUDY SKIES...WITH ISOLATED...MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. TEMPERATURES SHOULD BE NEAR SEASONAL AVERAGES. EK && .AVIATION... UPDATED 1110Z. A DRY WESTERLY FLOW ALOFT WILL CONTINUE THE VFR CONDITIONS OVER NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA THROUGH AT LEAST 12Z THURSDAY. ALTHOUGH SOME SMOKE WILL DRIFT OVER THE AREA FROM FOREST FIRES ACROSS THE WESTERN UNITED STATES...VISIBILITIES WILL MOSTLY REMAIN GREATER THAN 10SM. A WEAK DISTURBANCE IN THE FLOW MAY BRING A THUNDERSTORM OR TWO TO THE KHVR TERMINAL LATER THIS AFTERNOON THROUGH EARLY EVENING. GUSTY WINDS WILL BE THE MAIN THREAT FROM ANY THUNDERSTORMS THERE. OTHERWISE...SKIES WILL BE MOSTLY CLEAR. WEST WINDS WILL BECOME GUSTY ACROSS MOST OF THE AREA THIS AFTERNOON THROUGH EARLY EVENING (EXCEPT FOR THE KBZN TERMINAL)...WITH GUSTS POSSIBLY REACHING 35 KT AT TIMES ALONG THE ROCKY MOUNTAIN FRONT. COULSTON && .FIRE WEATHER...WARM AND DRY CONDITIONS WILL PERSIST TODAY. THERE WILL BE SOME SLIGHT AIRMASS INSTABILITY DURING THE AFTERNOON BUT THE LOW AMOUNT OF AVAILABLE MOISTURE WILL NEGATE ANY THUNDERSTORM FORMATION. MIN HUMIDITIES WILL DROP A FEW MORE PERCENT TODAY WITH BROAD AREA OF 15 TO 18 PERCENT EXPECTED IN MOST VALLEY/PLAINS LOCATIONS. WINDS WILL BE IN THE 15 TO 20 MPH RANGE TODAY. DRY CONDITIONS CONTINUE INTO THURS WITH WINDS INCREASING TO 30 TO 40 MPH AS AN UPPER LEVEL TROUGH APPROACHES FROM THE WEST. ALTHOUGH WEATHER CONDITIONS MAKE FOR MODERATE FIRE DANGER...CURRENT NON-CURED STATUS OF LOCAL FUELS WILL PRECLUDE ANY WATCHES OR WARNINGS AT THIS TIME. WARANAUSKAS |
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