917  
FXUS65 KTFX 191153  
AFDTFX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREAT FALLS MT  
553 AM MDT THU APR 19 2018  
   
..UPDATED AVIATION
 
 
   
SYNOPSIS
 
 
SLIGHTLY WARMER TEMPERATURES AND LINGERING CLOUDS WILL BE FOUND  
ACROSS THE REGION TODAY. MAINLY DRY CONDITIONS ARE ALSO  
EXPECTED...ALTHOUGH A FEW ISOLATED TO SCATTERED RAIN OR SNOW  
SHOWERS ARE POSSIBLE ACROSS THE SOUTHWEST. CLEARING SKIES AND  
NORMAL LOW TEMPERATURES ARE THEN EXPECTED FOR TONIGHT. FRIDAY WILL  
THEN SEE MAINLY DRY AND WARM TEMPERATURES...WITH SOME AREAS SEEING  
THE RETURN OF 60 DEGREE TEMPERATURES. A COLD FRONT THEN LOOKS TO  
BRING GUSTY WINDS AND ISOLATED TO SCATTERED SHOWERS ON SATURDAY.  
 

 
   
DISCUSSION
 
 
TODAY THROUGH SATURDAY...OVERALL A QUIET AND WARMING PATTERN IS  
EXPECTED TO END THE WORK WEEK...WITH A MAINLY DRY COLD FRONT  
POSSIBLE ON SATURDAY. A LARGE UPPER LOW WILL PASS TO OUR SOUTH  
TODAY...BRINGING SOME INCREASED CLOUD COVER...AND PERHAPS SOME  
LOW IMPACT SCATTERED RAIN OR SNOW SHOWERS ACROSS FAR SOUTHWESTERN  
PORTIONS. NEAR NORMAL TEMPERATURES IN THE 40S AND 50S ARE ALSO  
EXPECTED TODAY. THIS LOW WILL PUSH EASTWARD TONIGHT INTO  
FRIDAY...LEAVING US IN BETWEEN SYSTEMS. THE RESULT WILL BE  
CONTINUED WARMING TEMPERATURES...CLEARING SKIES...AND MAINLY DRY  
CONDITIONS. SOME AREAS COULD SEE THE RETURN OF 60 DEGREE  
TEMPERATURES ON FRIDAY...WHICH FOR SOME ARE APPROACHING RECORD  
LATEST TIME OF THE YEAR FOR THE FIRST 60 DEGREE DAY. SATURDAY'S  
WEATHER WILL THEN BE DRIVEN BY A SHARP...BUT MAINLY DRY...COLD  
FRONT THAT WILL PASS ACROSS THE STATE FROM WEST TO EAST. SHOWER  
ACTIVITY FROM THIS FRONT WILL BE LIMITED TO THE WESTERN  
MOUNTAINS...AND PERHAPS AN ISOLATED SHOWER ACROSS THE PLAINS.  
STRONG WINDS FROM THIS FRONT ARE POSSIBLE...ESPECIALLY ACROSS THE  
PLAINS AND THE ROCKY MOUNTAIN FRONT. MODELS SHOWING 700 MB WIND  
OVER 50 KNOTS. WITH A SHARP FRONT LIKE THIS...IT WOULD BE EASIER  
TO MIX DOWN THESE WINDS TO THE SURFACE. WILL HAVE TO BE MONITORED  
FOR A HIGH WIND WATCH...ESPECIALLY FOR THE ROCKY MOUNTAIN FRONT  
ZONES AND ADJACENT HIGH PLAINS ZONES. THIS DOWN SLOPING WIND WILL  
BRING FURTHER WARMING CONDITIONS FOR SATURDAY...WITH PERHAPS SOME  
70S POSSIBLE ACROSS THE EAST. WARM TEMPERATURES WILL ONCE AGAIN  
BRING HYDRO CONCERNS FOR MELTING SNOW. SEE THE HYDRO DISCUSSION  
FOR MORE DETAILS. MELTING SNOW COULD ALSO HELP SATURATE THE AIR AT  
NIGHT...PERHAPS BRINGING SOME PATCHY FOG...ESPECIALLY FRIDAY  
MORNING. SATURDAY MAY ALSO PRESENT SOME FIRE WEATHER CONCERNS FOR  
THOSE DOING SOME SPRING AG BURNING AS RH WILL BE MODERATELY  
LOW...AND STRONG WINDS WILL ACCOMPANY THE FRONT. ALTHOUGH CRITICAL  
FIRE WEATHER CONDITIONS ARE NOT EXPECTED...THOSE BURNING MAY WANT  
TO DELAY ANY OPERATIONS ON SATURDAY TO A LESS WINDY DAY.  
 
SATURDAY NIGHT THROUGH THURSDAY...THE SHORTWAVE TROUGH AND PACIFIC  
COLD FRONT WILL MOVE EAST OF THE AREA SATURDAY NIGHT, WHICH SHOULD  
DECREASE THE WINDS AND MOVE OUT ANY LINGERING SHOWERS. WEAK HIGH  
PRESSURE WILL THEN KEEP THE AREA DRY WITH NEAR NORMAL TEMPERATURES  
FOR SUNDAY. ANOTHER SHORTWAVE WITH MORE OF A CANADIAN COLD FRONT  
WILL MOVE SOUTHEAST THROUGH THE AREA SUNDAY NIGHT INTO MONDAY,  
CAUSING WINDS TO SHIFT MORE NORTHERLY AND FOCUS A GOOD CHANCE OF  
RAIN AND SNOW SHOWERS MORE SO OVER CENTRAL AND SOUTHWEST MONTANA.  
LIGHT MEASURABLE SNOW IS POSSIBLE IN THE CENTRAL AND SOUTHWEST  
MOUNTAINS AS TEMPERATURES FALL JUST BELOW NORMAL. HIGH PRESSURE WILL  
MOVE BACK INTO THE AREA TEMPORARILY MONDAY NIGHT INTO TUESDAY, FOR  
DRYING CONDITIONS WITH ABOVE NORMAL TEMPERATURES. FORECAST MODELS  
THEN BEGIN TO DIVERGE WITH THEIR SOLUTIONS FOR THE MIDDLE OF NEXT  
WEEK. THE GFS MODEL DEEPENS A LOW PRESSURE TROUGH OVER MONTANA, THE  
CANADIAN MODEL MOVES THE TROUGH INTO THE GREAT BASIN, AND THE ECMWF  
PUTS IT OFF THE CALIFORNIA COAST, WHICH KEEPS THE FORECAST AREA  
UNDER A HIGH PRESSURE RIDGE. THE GFS SOLUTION WOULD BRING THE BEST  
CHANCE FOR PRECIPITATION, WHILE THE CANADIAN/ECMWF SOLUTIONS REMAIN  
GENERALLY DRY. WILL THEREFORE KEEP ONLY A SLIGHT CHANCE OF SHOWERS  
IN THE FORECAST UNTIL SOME CONSENSUS CAN BE REACHED. HAVE ALSO KEPT  
TEMPERATURES CLOSE TO OR SLIGHTLY ABOVE NORMAL FOR WEDNESDAY INTO  
THURSDAY. COULSTON  
 

 
   
AVIATION
 
 
UPDATED 1200Z.  
 
VFR CONDITIONS WILL PREVAIL THROUGH TODAY AS A WEAK DISTURBANCE  
PASSES TO THE SOUTH OF MONTANA. GENERALLY DRY CONDITIONS...PARTLY  
CLOUDY SKIES...AND EASTERN WINDS ARE EXPECTED FOR  
TODAY...ALTHOUGH SOME SCATTERED SHOWER ACTIVITY IS POSSIBLE ACROSS  
FAR SOUTHWESTERN MONTANA. MAINLY DRY CONDITIONS AND LIGHT WINDS  
ARE EXPECTED FOR TONIGHT. SOME AREAS COULD SEE PATCHY FOG DEVELOP  
LATE TONIGHT INTO EARLY FRIDAY MORNING. CONFIDENCE REMAINS  
LOW...AND HAVE PLACED IN VCFG FOR SITES WITH THE BEST CHANCES.  
OTHERWISE VFR CONDITIONS SHOULD PREVAIL FOR TONIGHT. ANGLIN  
 

 
   
HYDROLOGY
 
 
UPDATED 840 PM WEDNESDAY (4/18).  
 
FLOODING CONTINUES TO AFFECT NORTHERN AND NORTHEAST PORTIONS OF  
NORTH-CENTRAL MT THIS EVENING WITH FLOOD WARNINGS FOR SEVERAL  
POINTS ALONG THE MILK RIVER AND ITS TRIBUTARIES IN HILL AND  
BLAINE COUNTIES AS WELL AS COUNTYWIDE FOR SMALLER CREEKS. AREAL  
FLOODING FROM CREEKS AND SNOW-MELT IS ALSO IMPACTING AREAS FURTHER  
WEST ACROSS LIBERTY, TOOLE AND PONDERA COUNTIES. SATELLITE  
IMAGERY THIS AFTERNOON STILL SHOWS A SIGNIFICANT THOUGH DWINDLING  
SNOWPACK IN PORTIONS OF THESE COUNTIES WITH ADDITIONAL RUN-OFF  
LIKELY TO CONTINUE TO PRODUCE HYDROLOGICAL ISSUES THROUGH THE NEXT  
SEVERAL DAYS AS TEMPERATURES GRADUALLY WARM. NEW POINT FLOOD  
WATCHES WILL BE ISSUED THIS EVENING FOR LODGE CREEK IN NORTHEAST  
HILL COUNTY AND THE MISSOURI RIVER AT LANDUSKY (NEAR THE FRED  
ROBINSON BRIDGE) WHERE RIVER STAGE MEASUREMENTS ARE INCREASING AND  
MAY REACH FLOOD STAGE IN THE NEXT 24 HRS. HOENISCH  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
GTF 57 32 64 39 / 10 10 0 0  
CTB 53 29 61 36 / 10 10 0 0  
HLN 58 33 63 38 / 10 10 0 0  
BZN 56 29 60 33 / 10 10 0 0  
WEY 47 22 50 22 / 20 20 0 0  
DLN 54 28 57 32 / 20 20 0 0  
HVR 56 29 56 35 / 10 10 0 0  
LWT 56 31 60 36 / 10 10 0 0  
 

 
   
TFX WATCHES/WARNINGS/ADVISORIES
 
 
FLOOD WARNING IN EFFECT UNTIL FURTHER NOTICE  
FOR BIG SANDY CREEK NEAR HAVRE.  
 
FLOOD WARNING IN EFFECT UNTIL FURTHER NOTICE  
FOR MILK RIVER NEAR HAVRE.  
 
FLOOD WARNING IN EFFECT UNTIL FURTHER NOTICE  
FOR BATTLE CREEK NEAR CHINOOK.  
 
FLOOD WARNING IN EFFECT UNTIL FURTHER NOTICE  
FOR MILK RIVER NEAR HARLEM.  
 
AREAL FLOOD WARNING IN EFFECT UNTIL 815 PM MDT SUNDAY  
FOR HILL...BLAINE COUNTIES.  
 
AREAL FLOOD WARNING IN EFFECT UNTIL 445 PM MDT MONDAY FOR  
LIBERTY...TOOLE COUNTIES.  
 
AREAL FLOOD ADVISORY IN EFFECT UNTIL 345 PM MDT FRIDAY  
FOR GLACIER COUNTY.  
 
AREAL FLOOD ADVISORY IN EFFECT UNTIL 815 AM MDT THURSDAY  
FOR TETON COUNTY.  
 
AREAL FLOOD ADVISORY IN EFFECT UNTIL 715 AM MDT FRIDAY FOR FERGUS  
COUNTY.  
 
AREAL FLOOD ADVISORY IN EFFECT UNTIL NOON MDT FRIDAY  
FOR EASTERN PONDERA COUNTY.  
 

 
 

 
 
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