704 FXUS65 KTFX 010458 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1050 PM MDT THU MAY 31 2012 UPDATED AVIATION SECTION .DISCUSSION... MADE MINOR CHANGES TO POPS TONIGHT TO RAISE AREAS ALONG THE ROCKY MOUNTAIN FRONT BY LINCOLN AND AUGUSTA AS MOISTURE FROM WESTERN MONTANA SPREADS TOWARDS THE CONTINENTAL DIVIDE. SOME SHOWERS ARE POSSIBLE IN THE CENTRAL MONTANA MOUNTAINS AS WELL. AFTER MIDNIGHT...SHOWER ACTIVITY WILL DECREASE AS A RIDGE OF HIGH PRESSURE BEGINS TO PUSH INTO THE REGION. MLV && .AVIATION... UPDATED 0450Z. WESTERLY FLOW ALOFT CONTINUES. ISOLATED SHOWERS WILL END BY 08Z WITH SKIES CLEARING BY DAYBREAK. VFR CONDITIONS PREVAIL WITH MVFR CONDITIONS IN THE VICINITY OF SHOWERS. && .HYDROLOGY... UPDATED 1620Z. THE FLOOD WARNING CONTINUES FOR CLEAR CREEK IN BLAINE COUNTY UNTIL FURTHER NOTICE. CLEAR CREEK IS EXPECTED TO REMAIN ABOVE FLOOD STAGE FOR AT LEAST ANOTHER 12 TO 24 HOURS. && .PREV DISCUSSION... /ISSUED 545 PM MDT THU MAY 31 2012/ TONIGHT THROUGH SATURDAY...A MOIST NORTHWESTERLY FLOW ALOFT WILL CONTINUE ACROSS THE REGION THROUGH MUCH OF THE SHORT TERM PERIOD. ISOLATED TO SCATTERED SHOWERS ARE EXPECTED DURING THE AFTERNOON AND EVENING HOURS TODAY AND AGAIN ON FRIDAY. A HIGH PRESSURE RIDGE ALOFT IS EXPECTED TO GRADUALLY PROGRESS EASTWARD EACH DAY AND WILL FINALLY MOVE ACROSS MONTANA ON SATURDAY. AS THE RIDGE AXIS MOVES EAST A MUCH MORE ACTIVE WEATHER PATTERN WILL DEVELOP WITH A SURFACE COLD FRONT PUSHING THROUGH MY FORECAST AREA DURING THE AFTERNOON. WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED AHEAD OF AND ALONG THE FRONTAL BOUNDARY WITH SOME STORMS POSSIBLY BECOMING BORDERLINE SEVERE. HAVE ISSUED A WEATHER STORY AND AN EMAIL NOTIFICATION ALERTING LOCAL CUSTOMERS THAT MODERATE TO STRONG THUNDERSTORMS ARE EXPECTED SATURDAY AFTERNOON. AT THIS TIME AM EXPECTING MOST STORMS TO REMAIN BELOW SEVERE CRITERIA WITH HEAVY RAIN...SMALL HAIL AND GUSTY WINDS EXPECTED. MPJ SATURDAY NIGHT THURSDAY...AN UPPER LEVEL HIGH PRESSURE RIDGE WILL HAVE MOVED EAST OF THE ZONES BY SATURDAY NIGHT. THE UPPER LEVEL FLOW WILL HAVE SWITCHED TO THE SOUTHWEST AHEAD OF A LOW PRESSURE TROF OVER THE EASTERN PACIFIC. A COLD FRONT WILL BE CROSSING THE ZONES DURING THE NIGHT AND TEMPERATURES WILL COOL TO NEAR NORMALS SUNDAY. THE AIRMASS WILL BECOME SLIGHTLY UNSTABLE DURING THE AFTERNOON BUT MAINLY ACROSS THE SOUTHWEST ZONES. MOISTURE WILL CONTINUE TO MOVE INTO THE AREA SUNDAY NIGHT AND MONDAY AND WIDESPREAD SHOWERS WILL DEVELOP. THE SOUTHWEST WILL AGAIN BECOME UNSTABLE DURING THE AFTERNOON ALONG WITH THUNDERSTORM DEVELOPMENT. A COOLING AIRMASS WILL DROP TEMPERATURES BELOW SEASONAL NORMALS ACROSS NORTHERN PORTIONS OF THE CWA. THE TROF OVER THE EASTERN PACIFIC WILL MOVE OVER THE WEST COAST MONDAY NIGHT AND APPROACH THE ROCKIES BY MORNING. THE AIRMASS WILL BECOME QUITE MOIST...AND INSTABILITY WILL DEVELOP AGAIN TUESDAY AFTERNOON. THE SURFACE PRESSURE GRADIENT WILL TIGHTEN AS THE TROF APPROACHES THE ROCKIES...AND VERY STRONG WINDS ARE EXPECTED ACROSS THE ZONES. THE LOW BECOMES VERY SLOW MOVING AND WILL LINGER ACROSS THE REGION THROUGH THURSDAY. THE UPPER LEVEL FLOW WILL REMAIN CYCLONIC THROUGH FRIDAY AND THE AIRMASS WILL REMAIN UNSETTLED. A SECOND TROF WILL MOVE INTO THE PACIFIC NORTHWEST...AND STRONG SURFACE WINDS WILL ONCE AGAIN DEVELOP ACROSS THE REGION. ZELZER && .PRELIMINARY POINT TEMPS/POPS... GTF 47 75 52 79 / 20 10 10 60 CTB 46 71 51 71 / 20 10 10 50 HLN 50 77 52 81 / 30 10 10 50 BZN 45 77 48 80 / 30 10 10 60 WEY 37 68 38 72 / 20 20 20 40 DLN 46 76 48 79 / 20 10 10 60 HVR 46 76 51 79 / 20 10 10 50 LWT 44 70 48 78 / 30 20 10 50 && .TFX WATCHES/WARNINGS/ADVISORIES... FLOOD WARNING FOR CLEAR CREEK IN BLAINE COUNTY NEAR THE TOWN OF CHINOOK UNTIL FURTHER NOTICE. && $$ WEATHER.GOV/GREATFALLS