000
FXUS63 KFGF 301244
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
644 AM CST SAT NOV 30 2013

.UPDATE...
ISSUED AT 644 AM CST SAT NOV 30 2013

WILL NEED TO INCREASE SKY TODAY. THE RAP GUIDANCE IS VERIFYING THE
BEST...SHOWING THE LOW LEVEL CIGS FROM CANADA ADVECTING INTO THE
FORECAST AREA. WILL FOLLOW THE 09Z RAP FOR ARRIVAL TIMES. WILL
ALSO KEEP THE REGION CLOUDY THROUGH THE OVERNIGHT HOURS.
FORECASTED MAX TEMPS TODAY MAY BE A BIT HIGH...BUT SHOULD BE IN
THE BALL PARK. FORECASTED MIN TEMPS TONIGHT ARE LIKELY TOO COLD
(IF CLOUDS STICK AROUND AS EXPECTED). WILL CONCENTRATE ON SKY FOR
THIS UPDATE...AND WORRY ABOUT TEMPS WITH THE NEXT UPDATES.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 337 AM CST SAT NOV 30 2013

00Z MODELS INITIALIZED WITH MINIMAL ERRORS AND ARE IN GOOD
AGREEMENT THROUGH SUNDAY. THE CHALLENGE FOR TODAY WILL BE
TEMPERATURES AND CLOUD COVER. THE CHALLENGE FOR SUNDAY WILL BE -SN
CHANCES.

TODAY-TONIGHT...WEAK COLD FRONT WILL BE THROUGH THE REGION WHICH
SHOULD LEAD TO SLIGHTLY COOLER TEMPERATURES THAN YESTERDAY. THE
MID-LEVEL CLOUDS ALONG AND AHEAD OF THIS FEATURE WILL MOVE
SOUTH...BUT WILL NEED TO WATCH THE LOW-LEVEL CIGS APPROACHING FROM
THE NORTH. 06Z RAP IS MOST AGGRESSIVE BRINGING THESE CIGS INTO THE
ENTIRE FA...WHILE MOST OTHER GUIDANCE SUGGESTS ONLY PORTIONS OF NW
MN WILL BE AFFECTED. WILL SIDE WITH THE MAJORITY...AND TAKE A
CLOSER LOOK AT THE 7AM UPDATE.

SUNDAY...00Z MODELS HAVE SLOWED THE SHORTWAVE BRINGING -SN
CHANCES...ADJUSTED POPS ACCORDINGLY. MUCH OF SUNDAY SHOULD BE DRY
(UNTIL THE EVENING HOURS).

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 337 AM CST SAT NOV 30 2013

SUNDAY NIGHT-MONDAY NIGHT...00Z MODELS BEGIN TO DIVERGE...WITH THE
ECMWF/GEM/UKMET DIGGING THE UPPER LOW INTO THE NW CONUS BY 12Z
TUE...AND THE NAM/GFS BRINGING THIS FEATURE INTO MONTANA/WESTERN
DAKOTAS. THE ECMWF/GEM/UKMET HAVE BEEN THE MORE CONSISTENT
MODELS...AND ARE SUPPORTED BY ENSEMBLES (WILL FOLLOW FOR FORECAST
DETAILS). THERE WILL BE A COUPLE LEAD SHORTWAVES EJECTING FROM THE
MAIN UPPER TROUGH. THE FIRST WILL MOVE THROUGH THE REGION SUNDAY
NIGHT...AND THE SECOND MONDAY AFTERNOON/NIGHT. SINCE THERE HAVE
BEEN A FEW MODEL RUNS INDICATING THESE FEATURES...WILL INCREASE
POPS TO LIKELY AND ATTEMPT TO TIME THESE FEATURES THROUGH THE
REGION. THE FIRST WAVE IS WEAKER...AND SHOULD HAVE LESS AVAILABLE
MOISTURE. MESOSCALE FORCING IS ALSO WEAK...SO UP TO AN INCH OF
SNOWFALL APPEARS POSSIBLE (MAYBE 2 INCHES). THE SECOND WAVE IS
STRONGER...WITH MORE AVAILABLE MOISTURE (PWATS APPROACHING 0.5
INCHES). MODELS INDICATE A DEFINED CIRCULATION AT 850MB (AND A
WEAK 700MB LOW) PROPAGATING FROM NW ND INTO SE ND ON
MONDAY...LOSING DEFINITION MONDAY NIGHT AS IT PROPAGATES FURTHER
TO THE SE. ASSOCIATED WARM AIR ADVECTION/DEFORMATION COMBINED
WITH THE 0.5 INCH PWATS SHOULD LEAD TO A FEW INCHES OF SNOWFALL.
MODELS INDICATE 0.25-0.40 INCHES QPF ACROSS ALL BUT THE NE
FA...AND COMBINED WITH 12:1-13:1 SNOW RATIOS WOULD LEAD TO AN AREA
OF 3-5 INCHES OF SNOW. P-TYPE WILL BE ALL SNOW IF THE EXPECTED
SOLUTION VERIFIES. THE NAM/SREF/GFS HAVE WARMER MID-LEVEL
TEMPERATURES SINCE THE UPPER WAVE IS CLOSER TO THE REGION (LOW
LEVEL SOUTHERLY FLOW IS STRONGER)...AND WOULD LEAD TO FZRA/RA
POTENTIAL (BUT THIS PROBABILITY SEEMS VERY LOW ATTM).

TUESDAY-FRIDAY...A VERY WINTRY PERIOD IS IN STORE...WITH THE MAIN
FOCUS INITIALLY BEING SNOW POTENTIAL THROUGH MID-WEEK FOLLOWED BY
A COLD ARCTIC AIR MASS SPILLING SOUTH.

MODEL SPREAD CONTINUES TO BE SIGNIFICANT...ALTHOUGH THE ECMWF HAS
SHOWN BETTER CONSISTENCY OVER THE PAST FEW RUNS...SO HAVE TRENDED A
BIT IN THAT DIRECTION. THE 00Z GFS/ECMWF BOTH BRING THE UPPER TROUGH
EASTWARD INTO THE PLAINS WED/THU. HOWEVER...A CHALLENGE CONTINUES TO
BE TIMING OF EMBEDDED WAVES. THE ECMWF REMAINS DEEPEST AND FARTHEST
WEST WITH SFC LOW DEVELOPMENT FROM THE CENTRAL PLAINS NORTHEAST INTO
ONTARIO IN CONJUNCTION WITH A STRONG SHORTWAVE TROUGH ASSOCIATED
WITH THE LIFTING UPPER LOW...WHILE THE GFS IS MORE PROGRESSIVE WITH
A WEAKER SFC LOW ASSOCIATED WITH A LEAD WAVE. THUS...THE ECMWF AND
TO A LESSER EXTENT THE GEM ARE MORE AGGRESSIVE WITH QPF. THE 500 MB
GFS ENSEMBLE MEAN HEIGHT FIELD GENERALLY SUPPORTS THE ECMWF BROADLY.
CONFIDENCE STILL IS RATHER LOW REGARDING THE PLACEMENT AND MAGNITUDE
OF SNOWFALL...ALTHOUGH THE MID-WEEK PERIOD WILL CONTINUE TO BEAR
WATCHING FOR ACCUMULATING SNOWFALL.

ARCTIC AIR WILL BLAST SOUTH DURING THE LATTER PART OF THE
WEEK INTO NEXT WEEKEND. THE ECMWF CONTINUES TO INDICATE 925 MB TEMPS
DOWN TO -20 TO -25C THURSDAY/FRIDAY BEHIND INITIAL SURGE OF COLD
ADVECTION. BLUSTERY WINDS WILL COMBINE WITH VERY COLD TEMPS TO
PRODUCE POTENTIALLY HAZARDOUS WIND CHILLS AT TIMES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 644 AM CST SAT NOV 30 2013

MAJOR CHANGE WITH THE 12Z TAF ISSUANCE TO BRING MVFR CIGS INTO THE
REGION TODAY. USED THE 09Z RAP FOR HELP WITH ARRIVAL TIMES.
SATELLITE IMAGERY INDICATES THESE CIGS CONTINUE TO ADVECT
SOUTHWARD FROM CANADA...WITH THE RAP GUIDANCE HANDLING THIS
SCENARIO THE BEST. THESE CIGS WILL LIKELY REMAIN THROUGH THE
OVERNIGHT HOURS.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

UPDATE...TG
SHORT TERM...TG
LONG TERM...TG/MAKOWSKI
AVIATION...TG