234
FXUS63 KBIS 171932
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
232 PM CDT TUE SEP 17 2019
SHORT TERM
(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 153 PM CDT TUE SEP 17 2019
A SURFACE LOW PRESSURE WITH AN ASSOCIATED COLD FRONT ALONG THE
NORTH DAKOTA/MONTANA BORDER THIS AFTERNOON IS FORECAST TO MOVE
EAST THROUGH TONIGHT. THE FRONT WILL BE THE FOCUS FOR SCATTERED
THUNDERSTORMS, SEVERAL MAY BE STRONG TO SEVERE.
WE SEE THE POTENTIAL FOR STRONG CONVECTION VERY LATE THIS
AFTERNOON, BUT THIS COULD SLIP TILL THIS EVENING, THROUGH
MIDNIGHT. THE 12Z GFS SHOWS THE 0-6 KM SHEAR ALIGNED WITH THE
FORECAST FRONTAL POSITIONS, WHICH SUGGEST THE STORM MODE WILL BE A
BIT MESSY AND COMPLEX, MAINLY MULTICELL WITH LINES WITH AN
ISOLATED SUPERCELL.
CORFIDI VECTORS ALSO SUGGEST SOME TRAINING, SO CAN'T RULE OUT
SOME HEAVY RAIN POTENTIAL WEST THIS EVENING AND OVERNIGHT.
THE PRECIPITABLE WATER IS RELATIVELY HIGH, BUT WITH CAPPING IN
PLACE, AND A RELATIVELY NARROW PERIOD FOR FREE CONVECTION ALONG
THE FRONT, FEEL THE HEAVY RAIN POTENTIAL IS REALISTICALLY LOW.
CONVECTION WILL BE EXITING THE REGION WEDNESDAY MORNING AS TEH
SHORTWAVE TROUGH MOVES THROUGH.
THE MUCH ABOVE TEMPERATURES THAT WERE ASSOCIATED WITH A STRONG
H500 RIDGE OVER THE CENTRAL AND NORTHERN PLAINS WILL BE COMING TO
AN END. HIGHS WEDNESDAY WILL BE IN THE LOWER TO MID 70S.
LONG TERM
(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 153 PM CDT TUE SEP 17 2019
AS THE H500 RIDGE DRIFTS EAST EARLY IN THE EXTENDED PERIOD
THURSDAY, A LARGE H500 TROUGH, CURRENTLY MOVING INTO THE PACIFIC
NORTHWEST WILL MIGRATE EAST BY WEEKEND. THIS WILL INITIALLY BRING
A LONG FETCH OF SOUTHWEST FLOW ALOFT FROM SOUTHERN CALIFORNIA
INTO THE NORTHERN PLAINS. LOW LEVEL MOISTURE WILL RETURN INTO THE
REGION AHEAD OF THIS SYSTEM, SETTING UP A SLOW MOVING COLD
FRONT/BAROCLINIC ZONE ACROSS THE NORTHERN PLAINS. WHAT CAN BE
EXPECTED IS A RATHER EXTENDED PERIOD OF SHOWERS AND THUNDERSTORMS
THURSDAY NIGHT, FRIDAY, AND FRIDAY NIGHT.
AGAIN, PRECIPITABLE WATER WILL BE WELL ABOVE NORMAL, AND
WIDESPREAD RAINFALL BETWEEN ONE AND 2 INCHES WILL BE POSSIBLE
THURSDAY NIGHT THROUGH FRIDAY NIGHT, WITH THE HIGHEST AMOUNTS
GENERALLY ACROSS THE NORTH.
COOLER, BUT MORE NORMAL TEMPERATURES IN TEH 60S TO AROUND 70 ARE
EXPECTED AT THIS TIME. SUNDAY THROUGH TUESDAY WILL SEE SOME
TRANSIENT SCATTERED SHOWERS, WITH HIGHS IN THE 60S.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1221 PM CDT TUE SEP 17 2019
A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT IN EASTERN
MONTANA THIS AFTERNOON IS FORECAST TO MOVE SLOWLY EAST THIS
FORECAST PERIOD. THE FRONT WILL BE THE FOCUS FOR THUNDERSTORMS
LATE THIS AFTERNOON SOUTHWEST AND ACROSS THE WESTERN HALF OF THE
STATE TONIGHT. VFR CONDITIONS ARE EXPECTED.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...WAA
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