000
FXUS63 KBIS 230658
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
158 AM CDT WED APR 23 2014

.UPDATE...

ISSUED AT 158 AM CDT WED APR 23 2014

UPDATED POPS BASED ON LATEST MODEL DATA AND RADAR IMAGERY...TRYING
TO FINE TUNE THE NEAR TERM BETWEEN NOW AND 12Z. SLIGHTLY EXPANDED
THE THUNDERSTORM MENTION...BUT LARGELY KEPT IT CONFINED TO THE
SOUTHWEST ADDING THE FAR SOUTH CENTRAL BASED ON LATEST NAM/RAP MID
LEVEL LAPSE RATES.

REMAINDER OF THE FORECAST REMAINS ON TRACK.


UPDATE ISSUED AT 934 PM CDT TUE APR 22 2014

LATE EVENING UPDATE MAINLY FOR POP/WEATHER TRENDS OVERNIGHT. BASED
IN PART OF THE 23/01Z RAP AND THE 23/00Z NAM...HAVE SLOWED THE
NORTHWARD PROGRESSION OF THE SHOWERS SLIGHTLY OVERNIGHT AND
BOOSTED POPS SOMEWHAT IN THE SOUTHWEST. ALSO FOLLOWED THE RAP
SHOWALTER INDEX PROGS TO TRIM BACK THE ISOLATED THUNDER OVERNIGHT
INTO THE FAR SOUTHWEST. SHOWERS AND A FEW THUNDERSTORMS WILL
CONTINUE WEDNESDAY...ESPECIALLY ACROSS THE NORTHEAST HALF OF THE
FORECAST AREA.

UPDATE ISSUED AT 629 PM CDT TUE APR 22 2014

NO SIGNIFICANT CHANGES FOR EARLY EVENING UPDATE. SHOWERS EXPECTED
TO DEVELOP BY LATE EVENING THEN SPREAD NORTH OVERNIGHT. AN
ISOLATED RUMBLE OF THUNDER IS NOT OUT OF THE QUESTION FAR WEST OVERNIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 335 PM CDT TUE APR 22 2014

GUSTY SOUTHEASTERLY WINDS WILL CONTINUE ACROSS WESTERN AND
CENTRAL NORTH DAKOTA LATER THIS AFTERNOON AND OVERNIGHT. THE
MODELS HAVE BEEN PERFORMING POORLY WITH RESPECT TO AFTERNOON
DEWPOINTS (TOO HIGH). AS A RESULT...MANUALLY ADJUSTED THE
AFTERNOON DEWPOINTS DOWN BASED ON THE CURRENT OBS/TRENDS. THE
COMBINATION OF HIGH WINDS AND LOW RELATIVE HUMIDITIES CONTINUE TO
GENERATE A VERY HIGH FIRE DANGER OVER WESTERN AND CENTRAL NORTH
DAKOTA THIS AFTERNOON. DEWPOINT RECOVERY SHOULD BEGIN IN EARNEST
AFTER SUNSET AS LOW-LEVEL MOISTURE GETS DRAWN UP OVER THE STATE
AHEAD OF AN APPROACHING LONGWAVE TROUGH.

THE MEDIUM RANGE MODELS PROG THAT LIGHT RAIN SHOWERS WILL BECOME
LIKELY AFTER MIDNIGHT AHEAD OF THE AFOREMENTIONED APPROACHING
LONGWAVE TROUGH. THE MAIN BAND OF WARM AIR ADVECTION/CONVEYOR BELT
PRECIPITATION IS EXPECTED TO DEVELOP FROM THE JAMES RIVER BASIN
AND EXTEND NORTHWEST INTO MINOT AND NORTHWESTERN NORTH DAKOTA.
FURTHERMORE...MARGINAL MID-LEVEL LAPSE RATES COMBINED WITH
INCREASING UPPER LEVEL FORCING COULD GENERATE A SLIGHT CHANCE FOR
THUNDERSTORMS WEST AFTER MIDNIGHT. HOWEVER...NO ORGANIZED SEVERE
WEATHER IS EXPECTED.

BY WEDNESDAY...THE MAIN PRECIPITATION BAND IS FORECAST TO LIFT
NORTHEAST AS THE ATTENDANT SURFACE TROUGH AXIS LIFTS NORTHEAST
ACROSS THE STATE. AGAIN...MARGINAL CONVECTIVE PARAMETERS WARRANT
AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS MENTION OVER CENTRAL AND
EASTERN NORTH DAKOTA...MAINLY ALONG THE BOUNDARY AS IT PUSHES
ACROSS THE STATE. THIS IS CONSISTENT WITH THE SPC DAY 2 OUTLOOK.

MARGINAL WIND ADVISORY CRITERIA MAY DEVELOP OVER SOUTHWESTERN
NORTH DAKOTA WEDNESDAY AFTERNOON. WILL HOLD OFF ON ISSUING ANY
WIND HEADLINES FOR THIS UPDATE AND WILL LET LATER SHIFTS DECIDE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 335 PM CDT TUE APR 22 2014

TWO VIGOROUS SYSTEMS WILL INFLUENCE THE WEATHER ACROSS WESTERN AND
CENTRAL NORTH DAKOTA IN THE LONG TERM PERIOD.

SYSTEM 1...

A WAVE MOVING ACROSS THE NORTHWEST U.S. AND SOUTHWEST
CANADA IS EXPECTED TO DEVELOP A CLOSED UPPER LEVEL CIRCULATION OVER
SOUTHERN BRITISH COLUMBIA/ALBERTA ON WEDNESDAY AND TRACK SLOWLY EAST
ALONG THE INTERNATIONAL BORDER THROUGH FRIDAY.

A SURFACE WARM FRONT IS FORECAST TO BE NEAR THE DEVILS LAKE AND
JAMES RIVER BASIN BY WEDNESDAY EVENING...WITH SOUTHEAST WINDS AHEAD
OF THE WARM FRONT AND WEST WINDS BEHIND IT. SCATTERED TO NUMEROUS
SHOWERS DURING THE DAY WEDNESDAY SHOULD BE MAKING THEIR WAY ALONG
AND AHEAD OF THE WARM FRONT...WITH A DRY SLOT BEHIND IT OVER
SOUTHWESTERN NORTH DAKOTA. THUS EXPECTING EVENING SCATTERED SHOWERS
NORTH THROUGH THE JAMES RIVER VALLEY...WITH MAINLY SLIGHT CHANCES OF
SHOWERS AFTER MIDNIGHT.

ON THURSDAY MORNING A SURFACE LOW ALONG THE NORTHERN BRANCH OF THE
WARM FRONT IS FORECAST TO BE SITUATED OVER SOUTHERN SASKATCHEWAN.
THIS LOW IS FORECAST TO MOVE SOUTHEAST ACROSS NORTH DAKOTA ON
THURSDAY...WITH A BAROCLINIC ZONE/BOUNDARY SETTING UP
NORTHWEST-TO-SOUTHEAST ACROSS THE STATE THURSDAY NIGHT. THIS
SCENARIO WILL BRING A CHANCE OF SHOWERS - BETTER CHANCES NORTH -
WITH THUNDERSTORMS POSSIBLE THURSDAY AFTERNOON.

LATE THURSDAY NIGHT AND FRIDAY A COLD FRONT MOVES SOUTH ACROSS THE
STATE...BRINGING A CHANCE OF RAIN OR SNOW SHOWERS - MAINLY NORTH IN
THE TURTLE MOUNTAINS...BUT WITH LITTLE OR NO SNOW ACCUMULATIONS.

SYSTEM 2...

DURING THIS TIME THE NEXT STRONG SYSTEM IS TAKING SHAPE OVER THE
WESTERN U.S. MODEL UNCERTAINTY INCREASES AS WE HEAD INTO THE WEEKEND
BUT IT APPEARS THAT THE UPPER LEVEL FLOW IS TRENDING SLOWER WITH A
BLOCKING PATTERN SETTING UP OVER THE CENTRAL PORTION OF THE COUNTRY.
THIS BLOCK MAINLY KEEPS A COLD HIGH PRESSURE SYSTEM OVER HUDSON BAY
WHILE A LARGE UPPER LEVEL LOW DEVELOPS ACROSS THE US ROCKIES AND
CLOSES OFF SOMEWHERE IN THE WESTERN/CENTRAL/SOUTHERN PLAINS. WILL
NEED TO KEEP AN EYE ON THE EVOLUTION OF THIS SYSTEM AS LATEST
DETERMINISTIC RUNS ARE COLDER AND WETTER ACROSS WESTERN AND CENTRAL
NORTH DAKOTA. UTILIZED A STRAIGHT MODEL BLEND FOR THE EXTENDED AND
THIS IS DEPICTING PRECIPITATION ACROSS MAINLY THE SOUTHWEST ON
SATURDAY...THEN SPREADING ACROSS MOST OF THE AREA SUNDAY THROUGH
MONDAY. WITH COLDER TEMPERATURES EXPECTED BY THE WEEKEND
PRECIPITATION CHANCES WERE MAINLY RAIN DURING THE AFTERNOON AND
EARLY EVENING...WITH A MIX OF RAIN AND SNOW DURING THE OVERNIGHT AND
EARLY MORNING HOURS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)

ISSUED AT 158 AM CDT WED APR 23 2014

BREEZY CONDITIONS WILL CONTINUE OVERNIGHT INTO WEDNESDAY WITH A
SOUTHEAST WIND GUSTING OVER 20 KTS. SHOWERS DEVELOPING SOUTH TO
NORTH BETWEEN 06Z AND 09Z AND CONTINUE PAST DAYBREAK...FOLLOWED
BY A LATE MORNING LULL AND ADDITIONAL SHOWERS WEDNESDAY
AFTERNOON/EVENING. WINDS WILL SHIFT FROM SOUTHEAST TO MORE
WESTERLY LATER IN THE DAY WEDNESDAY AND WEDNESDAY NIGHT AS A
FRONTAL BOUNDARY PUSHES EAST ACROSS THE STATE.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

UPDATE...NH
SHORT TERM...TM
LONG TERM...JV
AVIATION...NH