FXUS65 KMSO 201502 AFDMSO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 901 AM MDT THU MAY 20 2004 .UPDATE...FORECASTS LOOK ON TRACK. IT APPEARS THE MAIN CONVECTIVE FOCUS SHOULD BE ALONG A SURFACE AND UPPER LEVEL BOUNDARY. THIS BOUNDARY IS CURRENTLY FROM LOWELL TO MISSOULA AND DRUMMOND AND SHIFTING VERY SLOWLY NORTHWARD. HOWEVER...OTHER AREAS WILL ALSO BE PRONE TO SEE SIGNIFICANT CONVECTION...ESPECIALLY WITH MORE HEATING AND UNSTABLE CONDITIONS. WEDNESDAYS CONVECTION PRODUCED UP TO A HALF INCH OF RAIN IN LESS THAN ONE HOUR. SO...GIVEN THE ATMOSPHERE IS AS MOIST AS WEDNESDAY AND LIKELY MORE UNSTABLE AND MORE HEATING TODAY...BRIEF HEAVY RAIN IS POSSIBLE WITH ANY OF THE STORMS. THESE RAIN FALL RATES MAY BE ENOUGH TO PRODUCE SIGNIFICANT RUNOFF...FLASH FLOODING OR DEBRIS FLOWS ON 2003 SEVERE BURN AREAS... THATS IF...THE STORM HITS THE BURN AREA. HOWEVER...THE OVERALL EXPECTED STORM COVERAGE AND UNCERTAINTY IN THE EXACT POSITION OF ANY ONE STORM DICTATES ONLY CLOSE MONITORING AT THIS POINT. IF CONDITIONS BECOME FAVORABLE FOR HEAVY RAINS THAT COULD PRODUCE FLASH FLOODING...A FLASH FLOOD WATCH WILL BE ISSUED. A FLASH FLOOD WARNING WILL BE ISSUED IF LIFE AND PROPERTY THREATENING FLOODING RAINS ARE OBSERVED OR IMMINENT...JUST A LITTLE REMINDER OF THE WATCH/WARNING CRITERIA...SINCE THERE IS A LOW TO MODERATE POTENTIAL TODAY...MAINLY 2003 SEVERE BURN AREAS. && .PREVIOUS DISCUSSION...TODAY THROUGH SATURDAY...CURRENT FORECAST LOOKED PRETTY GOOD. THERE WILL BE A BIT MORE SUNSHINE TODAY THAN YESTERDAY AND ALLOW TEMPERATURES TO INCREASE SLIGHTLY TO NEAR NORMAL READINGS. THE BIG CONCERN OF THE DAY WILL BE THUNDERSTORM ACTIVITY...ESPECIALLY IN NORTHERN MONTANA AND THE CLEARWATER MOUNTAIN REGION...WHERE PROBABILITY OF SHOWERS AND THUNDERSTORMS HAS BEEN INCREASED IN MANY AREAS TO NUMEROUS...ESPECIALLY LATER IN THE AFTERNOON AND EVENING...AS ANOTHER SHORT WAVE MOVES DOWN THE LONG WAVE TROUGH FROM BRITISH COLUMBIA INTO NORTHERN MONTANA BY LATE AFTERNOON INTO THE EVENING HOURS. THIS INCREASED INSTABILITY... MOISTURE ALREADY IN PLACE AND SOLAR HEATING WILL ALLOW FOR SHOWER AND THUNDERSTORM ACTIVITY...ESPECIALLY IN NORTHERN MONTANA. THUNDERSTORMS ON WEDNESDAY DID PRODUCE LOCAL HEAVY DOWNPOURS OF RAIN AND GUSTY DOWNBURST WINDS TO 25-30 MPH AT TIMES ALONG WITH ONE STORM PRODUCING HALF INCH HAIL. CONVECTIVE PARAMETERS LOOK A LITTLE BIT STRONGER FOR THIS AFTERNOON AND THIS EVENING WITH THIS NEXT SHORT WAVE MOVING INTO THE REGION. THE QUESTION IS WILL THERE BE ENOUGH SOLAR HEATING TO TRIGGER POTENTIALLY STRONG STORMS. THE CURRENT THOUGHT NOW IS IT IS A POSSIBILITY FOR STORMS WITH HEAVY RAIN WHICH COULD POSE A THREAT IF EVERYTHING LINES UP RIGHT TO THE 2003 BURN AREAS. NOT MUCH CHANGE WITH THE FRIDAY AND SATURDAY OUTLOOK AS ANOTHER SHORT WAVE MOVES THROUGH FROM BRITISH COLUMBIA ON FRIDAY AND BECOMING MORE OF A CLOSED LOW SYSTEM ON SATURDAY. THIS CLOSED LOW WILL LOWER TEMPERATURES ABOUT 5-10 DEGREES AND SNOW LEVELS REGION WIDE A FEW THOUSAND FEET AND PROVIDE FOR A CONTINUING WET OUTLOOK. SATURDAY NIGHT THROUGH WEDNESDAY...COOL UPPER LEVEL LOW PRESSURE SYSTEM WILL DOMINATE THROUGH TUESDAY. THIS WILL KEEP TEMPERATURES ON THE COOL SIDE AND PRECIPITATION GOING. SUNDAY NIGHT THE UPPER TROUGH WILL DIG FORMING A CUTOFF LOW OFF THE COAST OF CENTRAL CALIFORNIA. BEYOND TUESDAY SOME DISCREPANCIES IN THE MODELS ARE EVIDENT. GIVEN THE ACTIVE PATTERN AND THE LINGERING CUTOFF LOW HAVE OPTED TO KEEP A CHANCE OF PRECIPITATION IN THE FORECAST AND CONTINUE THE SLOW WARMING TREND. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && $$ UPDATE/BAUCK PREVIOUS DISCUSSION/RPN/GILCHRIST